JP7810269B2 - Separation membrane condition diagnosis method, condition diagnosis program, condition diagnosis device, and recording medium device - Google Patents

Description

The present invention relates to a separation membrane condition diagnosis method, a condition diagnosis program, a condition diagnosis device, and a recording medium device.

In recent years, membrane-based separation technologies for mixtures, such as gas separation membranes, reverse osmosis membranes, nanofiltration membranes, ultrafiltration membranes, and microfiltration membranes, have attracted attention as high-precision, energy-saving treatment processes, and their use in various water treatment processes is expanding. For example, in reverse osmosis separation methods using reverse osmosis membranes, a solution containing solutes such as salt is forced through the membrane at a pressure equal to or greater than the osmotic pressure of the solution, yielding a liquid with a reduced solute concentration. This method is widely used in the desalination of seawater and brine, the production of ultrapure water, and the concentration and recovery of valuable resources.

In plants using reverse osmosis membranes, oxidizing substances such as sodium hypochlorite are added as a means of preventing and reducing membrane surface contamination, known as fouling. However, these oxidizing substances are known to change the chemical structure of separation membranes, resulting in changes in membrane performance. Therefore, technologies to detect these changes are needed when using separation membranes. One method for determining chemical changes caused by oxidizing substances is the Fujiwara test, which involves reacting a separation membrane with an alkaline pyridine solution and checking for coloration (Non-Patent Document 1). While this method can easily identify contact with free chlorine or other substances, it has issues, such as the pungent odor of the pyridine solution and the difficulty of confirming coloration with colored separation membranes. Additionally, elemental composition analysis has also been used to detect halogenated structures, but this method has issues, such as its inapplicability when halogenated structures are removed due to chemical changes.

Journal of Membrane Science, 2010, Vol.347, P.159-164.

The present invention aims to provide a method for diagnosing the condition of a separation membrane by easily and quickly determining chemical changes and/or chemical changes in separation membrane performance, regardless of the degree of change, including chemical changes that were difficult to diagnose using conventional methods. Furthermore, it makes it possible to determine the type of chemical change and the causative substance, which was difficult to do using conventional techniques.

To solve the above problems, the present invention has the following features.

(1) A separation membrane condition diagnosis method for determining chemical changes and/or chemical changes in separation membrane performance of separation membrane 2 relative to separation membrane 1 based on a difference between an analysis result of separation membrane 1 and an analysis result of separation membrane 2, comprising :
The analysis results include the following infrared absorption spectroscopy results and elemental composition analysis results (1 ) :
The separation membrane contains polyamide and polysulfone,
The degree of chemical change and _{/ or} chemical change in separation membrane performance of separation membrane 2 relative to separation membrane 1 is estimated from the difference between the infrared absorption spectroscopy result (1) RA ÷ RD of separation membrane 1 and the infrared absorption spectroscopy result (1) RA ÷ _RD of _{separation membrane} 2 _, and the change profile relating to the correlation between the infrared absorption spectroscopy result (1) RA ÷ RD and separation membrane performance;
the degree of chemical change and/or chemical change in separation membrane performance of separation membrane 2 relative to separation membrane 1 is estimated from the difference between the elemental composition analysis results of separation membrane 1 and separation membrane 2 and a change profile relating to the correlation between the elemental composition analysis results and separation membrane performance;
A separation membrane condition diagnosis method characterized by _determining at least one of the degree of change , the type of chemical change, and the causative substance based on the estimated result of separation membrane performance change based on the infrared absorption spectroscopy result (1) RA _÷ RD and the estimated result of separation membrane performance change based on the elemental composition analysis result.
(1) R _A ÷ R _D
( where R _A is the maximum infrared absorption intensity in the range of 1680 to 1650 cm ⁻¹ , and R _D is the maximum infrared absorption intensity in the range of 1260 to 1230 cm ⁻¹ .)

( 2 ) A separation membrane condition diagnosis method according to (1), characterized in that the analysis results of the separation membrane 1 are the analysis results of an unused separation membrane, and the change profile relating to the analysis results is a correlation between the analysis results and at least one of the following indicators of separation membrane performance: removal rate, permeability, solvent permeability coefficient, solute permeability coefficient, solvent permeation amount, and solute permeation amount.

( 3 ) The separation membrane condition diagnosis method according to (1), characterized in that the elemental composition analysis result is at least one of the following:
1. Ratio of halogen elements to carbon elements 2. Ratio of oxygen elements to carbon elements 3. Ratio of nitrogen elements to carbon elements ( 4 ) The separation membrane state diagnosis method according to (1) , characterized in that the change profile relating to the analysis results is a correlation with at least one of the separation membrane performance factors, the removal rate, the solute permeability coefficient, and the solvent permeation amount, and at least one of the type of chemical change or the causative substance is determined from the difference between the estimated result of the separation membrane performance change based on the infrared absorption spectroscopy result ( 1 ) _RA ÷ _RD and the estimated result of the separation membrane performance change based on the elemental composition analysis result.

( 5) The separation membrane condition diagnosis method according to (1), wherein the elemental composition analysis result is 1. the ratio of halogen elements to carbon elements in ( 3 ).

( 6 ) The separation membrane condition diagnosis method according to (4), characterized in that, when the degree of change is determined to be mild or moderate by the method according to (1), if the ratio _Sr1 of the solute permeability coefficient of the target separation membrane performance calculated using the difference between _RA and _RD as described in 1. (1) is three times or less ( _Sr1 ÷ _Sr2 ≦ 3) the ratio _Sr2 of the solute permeability coefficient of the target separation membrane performance estimated using the difference between the ratios of halogen elements to carbon elements as described in 1. (3), the causative substance is determined to be a halogen-based agent, and if it is more than three times ( _Sr1 ÷ _Sr2 > 3), the causative substance is determined to be other than a halogen-based agent.

( 7 ) The separation membrane condition diagnosis method according to (1), characterized in that the elemental composition analysis results are analysis results obtained by irradiating the separation membrane with X-rays or electron beams from the functional layer side.

( 8 ) The separation membrane condition diagnosis method according to (1), characterized in that the separation membrane is any one of the following:
A: A separation membrane collected from a semipermeable membrane element that separates feed water into permeate and concentrate at a water treatment plant. B: A separation membrane installed inside a water-permeable member installed in a water supply line at a water treatment plant. C: A separation membrane installed inside a water-permeable member installed in a concentrate line at a water treatment plant, where a semipermeable membrane element that separates feed water into permeate and concentrate is used. ( 9) In order to determine the state of the separation membrane, a computer is used as a data input means for inputting the analysis results of the separation membrane into the computer, a data recording means for recording the input data in the computer, and a means for determining chemical changes in the separation membrane and/or chemical changes in the performance of the separation membrane based on the input and/or recorded data. Based on the difference between the analysis results of separation membrane 1 and the analysis results of separation membrane 2,
The analysis results include the following infrared absorption spectroscopy results and elemental composition analysis results (1 ) :
The separation membrane contains polyamide and polysulfone,
The degree of chemical change and _{/ or} chemical change in separation membrane performance of separation membrane 2 relative to separation membrane 1 is estimated from the difference between the infrared absorption spectroscopy result (1) RA ÷ RD of separation membrane 1 and the infrared absorption spectroscopy result (1) RA ÷ _RD of _{separation membrane} 2 _, and the change profile relating to the correlation between the infrared absorption spectroscopy result (1) RA ÷ RD and separation membrane performance;
the degree of chemical change and/or chemical change in separation membrane performance of separation membrane 2 relative to separation membrane 1 is estimated from the difference between the elemental composition analysis results of separation membrane 1 and separation membrane 2 and a change profile relating to the correlation between the elemental composition analysis results and separation membrane performance;
At least one of the degree of change , the type of chemical change, and the causative substance is determined based on the result of estimating the change in separation membrane performance based on the infrared absorption spectroscopy result (1) R _A ÷ R _D and the result of estimating the change in separation membrane performance based on the result of elemental composition analysis,
A separation membrane condition diagnosis program that functions as condition diagnosis means for determining chemical changes and/or chemical changes in separation membrane performance of separation membrane 2 relative to separation membrane 1 .
(1) R _A ÷ R _D
( where R _A is the maximum infrared absorption intensity in the range of 1680 to 1650 cm ⁻¹ , and R _D is the maximum infrared absorption intensity in the range of 1260 to 1230 cm ⁻¹ .)

( 10 ) The separation membrane condition diagnosis program according to (9), characterized in that the change profile relating to the analysis results is a correlation between the analysis results and at least one of the following indicators representing separation membrane performance: removal rate, permeability, solvent permeability coefficient, solute permeability coefficient, solvent permeation amount, and solute permeation amount.
( 11 ) The separation membrane condition diagnosis program according to ( ₉ ), characterized in that, when the degree of change is determined to be mild or moderate, if the ratio _Sr1 of the solute permeability coefficient of the target separation membrane performance calculated using 1. RA ÷ _RD is 3 times or less ( _Sr1 ÷ Sr2 _≦ 3) the ratio _Sr2 of the solute permeability coefficient of the target separation membrane performance estimated using the ratio of halogen elements to carbon elements in 1. of the elemental composition analysis results, the causative substance is determined to be a halogen-based agent, and if it is more than 3 times ( _Sr1 ÷ _Sr2 > 3), the causative substance is determined to be other than a halogen-based agent.

( 12 ) A separation membrane condition diagnosis device equipped with the separation membrane condition diagnosis program described in (9).

( 13 ) A computer-readable recording medium device having the separation membrane state diagnosis program according to ( 9 ) recorded thereon.

The present invention makes it possible to easily and quickly determine chemical changes and/or chemical changes in separation membrane performance, regardless of the degree of change, including chemical changes that were difficult to diagnose using conventional methods, making it possible to diagnose the condition of separation membranes regardless of the degree of change. Furthermore, it is possible to determine the type of chemical change and the substance causing it, which was difficult to do using conventional technology.

[Figure 1] An example of the flow of a water treatment plant.
FIG. 2 is a graph showing an example of a profile of changes in analytical results according to the progress of chemical reactions in the present invention.
FIG. 3 is a graph showing an example of a change profile using the difference between the analytical result of an unused separation membrane and the analytical result of an analysis according to the progress of chemical change in the present invention.
[Figure 4] A graph showing an example of a method for determining chemical changes and/or chemical changes in separation membrane performance in a fourth embodiment of the present invention, based on the difference between the change profile of the analysis results according to the progress of chemical changes and the analysis results of the target separation membrane.
[Figure 5] In a sixth embodiment of the present invention for determining chemical changes in a separation membrane, the change profile relating to the analysis results is a correlation with at least one of the removal rate, solute permeability coefficient, and solvent permeation amount, and the analysis results are infrared absorption spectroscopy results, and is a graph showing an example of a change profile for calculating the target separation membrane performance _S1 from the difference with the infrared absorption spectroscopy results of the target separation membrane.
[Figure 6] A graph showing an example of a change profile for calculating target separation membrane performance S2 from the difference with the elemental composition analysis result of the target separation membrane in a sixth embodiment of the present invention for determining chemical changes in a separation membrane, in which the change profile relating to the analysis results is a correlation with at least one of the removal rate, solute permeability coefficient, and _solvent permeation amount, and the analysis results are elemental composition analysis results.
[Fig. 7] A schematic diagram showing an example of a water-permeable member used in the present invention.
[Fig. 8] An example of a separable water-passing container constituting the water-passing member used in the present invention is shown.
[FIG. 9] An example of a program for executing the first embodiment of the present invention, that is, the diagnosis of the state of a separation membrane using the difference between the analysis results of a target separation membrane and the analysis results of an unused separation membrane, on a computer.
[Figure 10] An example of a program for executing the second embodiment of the present invention, i.e., a separation membrane condition diagnosis on a computer using the difference between the analysis results of the target separation membrane and the change profile related to the analysis results according to the progress of chemical changes.
[FIG. 11] An example of a program for executing the third embodiment of the present invention, that is, the diagnosis of the state of the separation membrane using the results of infrared absorption spectroscopy, on a computer.
FIG. 12 is an example of a program for executing, on a computer, the fourth embodiment of the present invention, that is, the diagnosis of the state of the separation membrane using the results of elemental composition analysis.
[Fig. 13] An example of a program for executing on a computer the fifth embodiment of the present invention, that is, the diagnosis of the state of the separation membrane by estimating the degree of change based on the results of infrared absorption spectroscopy and further using the results of elemental composition analysis.
[Figure 14] An example of a program for a computer to diagnose the state of a separation membrane using a plurality of infrared absorption spectroscopy results, i.e., to estimate the degree of change based on the infrared absorption spectroscopy results and further diagnose the state of the separation membrane using the infrared absorption spectroscopy results, in the third embodiment of the present invention.
[Figure 15] An example of a program for executing on a computer a state judgment of a separation membrane in the second to fifth embodiments of the present invention, in which the degree of change is estimated based on the results of infrared absorption spectroscopy, the state diagnosis of the separation membrane is judged multiple times using multiple infrared absorption spectroscopy results and/or elemental composition analysis results, and the results are integrated to make a final judgment.
FIG. 16 is an example of a program for executing, on a computer, the sixth embodiment of the present invention, that is, the diagnosis of the state of a separation membrane using the results of infrared absorption spectroscopy and elemental composition analysis.
FIG. 17 is a graph showing the relationship between solvent permeability coefficient and infrared absorption spectroscopy results according to an embodiment of the present invention.
FIG. 18 is a graph showing the relationship between solute permeability coefficient and infrared absorption spectroscopy results according to another embodiment of the present invention.
FIG. 19 is a graph showing the relationship between solute permeability coefficient and elemental composition analysis results according to another embodiment of the present invention.

In order to solve the above problems, the present invention has the following features. Below, the details of the present invention are explained using examples in the drawings, but the contents of the present invention are not limited to these drawings.

The present invention is a method for diagnosing the condition of a separation membrane, which is characterized by diagnosing the condition of the separation membrane by determining chemical changes and/or changes in chemical separation membrane performance in either one of the membranes based on the difference between the analysis results of separation membrane 1 and separation membrane 2.

In the present invention, the chemical change in separation membrane performance refers to a change in separation membrane performance caused by a chemical change, i.e., a change in chemical structure. Because the change is caused by a chemical change, the presence or absence of a chemical change in separation membrane performance and the causative substance are the same as the presence or absence of a chemical change and the causative substance.
(Subject of analysis)
A separation membrane is a membrane that allows only some components (substances) to pass through. For example, it is a semipermeable membrane that allows solvents to pass through but not solute components such as salts. Examples include nanofiltration membranes (NF membranes) and reverse osmosis membranes (RO membranes). The membrane structure includes a dense separation layer (separation functional layer) on one side of the membrane, and examples include asymmetric membranes with gradually increasing pore sizes from the dense separation layer toward the inside of the membrane or the other side, and composite membranes with a very thin separation functional layer made of a different material on top of the dense layer of the asymmetric membrane. Membrane forms include hollow fiber membranes and flat membranes.

Separation membranes of the present invention include microfiltration membranes (MF), ultrafiltration membranes (UF membranes), nanofiltration membranes (NF membranes), and reverse osmosis membranes (RO membranes). Among these, the present invention is particularly suitable for semipermeable membranes such as nanofiltration membranes (NF membranes) and reverse osmosis membranes (RO membranes) used for desalination of seawater and brine, production of industrial water, concentration of fruit juice, and advanced treatment of water supplies.

The separation membrane targeted in the analytical method of the present invention is not particularly limited in shape or material, but examples include composite materials in which a separation functional layer is formed on a microporous support layer. Its constituent components are not particularly limited, but include cellulose acetate, vinyl polymers, polyamides, polyesters, polyimides, polysulfones, etc. Cellulose acetate, polyamides, polyesters, and polysulfones are particularly desirable.

Examples of the separation membrane of the present invention include composite semipermeable membranes consisting of three layers: a substrate, a microporous support layer, and a separation functional layer.

The substrate and microporous support layer do not actually exhibit any separation performance for ions, etc., but serve to provide strength to the separation functional layer, which is responsible for the separation performance. The material and shape of the substrate are not particularly limited, but examples include fabrics or nonwoven fabrics primarily composed of at least one of polyester and polyamide. Polyester, which has high mechanical and thermal stability, is particularly preferred. The thickness of the substrate is generally within the range of 10 to 200 μm to ensure dimensional stability.

The material and shape of the microporous support layer provided between the substrate and the separation functional layer are not particularly limited, but it generally has a porous structure with fine pores of approximately 0.1 nm to 100 nm on the surface on which the separation functional layer is formed, and is obtained, for example, by phase separation of a high molecular weight polymer cast onto the substrate. A variety of polymeric materials, such as polysulfone, polyethersulfone, polyphenylene sulfide sulfone, polyphenylene sulfone, and cellulose acetate, are used alone or in combination as materials for the microporous support layer. Polysulfone, in particular, is commonly used due to its high chemical, mechanical, and thermal stability and ease of molding.

A wide variety of materials and structures have been developed for the separation functional layer that essentially exhibits the separation performance of ions and other substances in composite separation membranes. Examples include thin films made from materials such as polyamide, cellulose acetate, graphene, polystyrene sulfonic acid, polyallylamine, and siloxane derivatives. While not particularly limited in the present invention, cross-linked polyamide thin films, which have excellent water permeability and selective separation properties, are particularly preferred. Cross-linked polyamide separation functional layers are formed by the polycondensation reaction of polyfunctional amines and polyfunctional acid halides, and typically have a thickness of approximately 0.01 to 1 μm.

Separation membranes are generally used as elements in an appropriate form to match the membrane configuration, and separation membranes harvested from such elements can also be used as the separation membranes of the present invention. The separation membrane element in this invention is not particularly limited, as long as it has substantial liquid chambers on both sides of the separation membrane and can pressurize and permeate liquid from one surface of the separation membrane to the other. One example is a spiral-wound separation membrane element with a flat membrane configuration. A spiral-wound separation membrane element generally consists of a feed-side channel material that directs feed water to the separation membrane surface, a separation membrane, and a permeate-side channel material that directs the liquid that has permeated the separation membrane (permeate) to a water collection pipe, with the feed-side channel material, separation membrane, and permeate-side channel material spirally wound around the water collection pipe.

Another example of the separation membrane of the present invention is a separation membrane installed in a water treatment plant.

For example, Figure 1 shows an example of the flow of a water treatment plant. The water treatment plant shown in Figure 1 is composed of a raw water storage tank 1 that stores water to be treated (hereinafter referred to as raw water), a raw water supply pump 2 that supplies the raw water, a pretreatment membrane filtration unit 3 that filters the raw water, a pretreatment membrane filtrate storage tank 4 that stores the filtered water from the pretreatment membrane filtration unit 3, a separation membrane filtration unit 5, a booster pump 6 that supplies the filtered water from the pretreatment membrane filtration unit 3 to the separation membrane filtration unit 5, and a booster pump 7 that boosts the pressure of the filtered water from the pretreatment membrane filtration unit 3 so that it can be separated into permeate and concentrated water in the separation membrane filtration unit 5.

The raw water storage tank 1 and pretreatment membrane filtration unit 3 are connected by raw water piping 8, the pretreatment membrane filtration unit 3 and pretreatment membrane filtered water storage tank 4 are connected by pretreatment membrane filtered water piping 9, and the pretreatment membrane filtered water storage tank 4 and separation membrane filtration unit 5 are connected by separation membrane filtered feed water piping 10. In the water treatment plant, raw water is treated in the pretreatment membrane filtration unit 3, and the pretreatment membrane filtered water is temporarily stored in the pretreatment membrane filtered water storage tank 4 before being supplied to the booster pump 7 by the booster pump 6, where it is pressurized and supplied to the separation membrane filtration unit 5. There, it is separated into permeate, from which solutes such as salt have been removed, and concentrated water, from which solutes such as salt have been concentrated, and these are discharged through the separation membrane filtration permeate piping 11 and the separation membrane filtration concentrated water piping 12, respectively.

Examples of separation membranes of the present invention include separation membranes within separation membrane elements installed in the separation membrane filtration unit 5, as well as separation membranes extracted from components installed in the separation membrane filtration unit, and separation membranes within components installed in piping within the plant, such as raw water piping 8, pre-treated filtrate piping 9, separation membrane filtration feed water piping 10, separation membrane filtration permeate piping 11, and separation membrane filtration concentrated water piping 12.

(Analysis method)
The separation membrane used in the present invention is a thoroughly washed separation membrane. Examples of solutions used for washing include pure water or ultrapure water, as well as chemical solutions commonly used to remove fouling components from separation membranes. In particular, when fouling components adhere to the separation membrane, accurate diagnosis of chemical changes becomes difficult, making chemical washing desirable. Because the fouling components that adhere to separation membranes vary depending on the usage environment, various chemicals are used for washing. Specifically, acidic chemicals such as hydrochloric acid, sulfuric acid, and citric acid; alkaline chemicals such as sodium hydroxide and potassium hydroxide; surfactants such as sodium dodecyl sulfate and sodium polyoxyethylene lauryl sulfate; and chelating agents such as sodium ethylenediaminetetraacetate and sodium hexametaphosphate are preferably used. Methods for washing separation membranes with chemicals include, but are not limited to, immersing the separation membrane in an aqueous solution of the chemical or passing the aqueous solution through the separation membrane. However, it is preferable that the washing method does not cause chemical changes in the separation membrane. When preparing an aqueous solution by diluting the aforementioned chemicals, it is preferable to use pure water or ultrapure water, and ultrapure water is even more preferable.

The moisture content of the separation membrane of the present invention is preferably adjusted by drying or by adjusting the relative humidity at a constant temperature. Methods for drying the separation membrane include natural drying, as well as drying using an oven, a thermostatic chamber, or a vacuum dryer. From the perspective of improving diagnostic accuracy, drying in a low-pressure environment using a vacuum dryer equipped with a diaphragm pump or an oil-sealed rotary vacuum pump is preferred. The saturated salt method described in JIS B 7920:2000 can be used as a method for adjusting the relative humidity at a constant temperature. When performing the aforementioned washing, it is desirable to perform these moisture adjustment processes after washing, preferably immediately before analysis.

The analysis used in the present invention involves various analyses that detect chemical structure. Furthermore, the analytical results used in the present invention refer to values obtained by carrying out the aforementioned analyses, as well as values obtained through optional data processing and analysis. Commonly used analytical methods can be used to detect chemical structure, and although not limited to these, include the various techniques described below. It is preferable to use analyses that can detect chemical bonds such as functional groups and/or elemental composition analysis.

Infrared absorption spectroscopy is particularly preferred as an analysis capable of detecting various functional groups in the present invention. The infrared absorption spectroscopy of the present invention can be performed in accordance with the standard JIS K 0117. Furthermore, it is preferable to use attenuated total reflection infrared spectroscopy (ATR) in the present invention.

In the present invention, measurements can be performed using a general-purpose infrared absorption spectroscopy device, such as Shimadzu Corporation's IRSprit, IRAffinity-1S, and IRXrossIR Tracer-100; JASCO Corporation's FT/IR-4000 and 6000 series, FT/IR-4X, FT/IR-6X, and FT/IR-8X; and Thermo Fisher Scientific's Nicolet iS5, Nicolet iS20, Nicolet iS50, Nicolet iS50R, Spectrum Two, Spectrum Two+, and Spectrum 3. Measurement results can be analyzed using analysis software provided with the aforementioned devices.

The elemental composition analysis of the present invention is not particularly limited as long as it analyzes the composition of the constituent elements of the separation membrane. Examples of suitable methods include electron probe microanalyzers (EPMA), Auger electron spectroscopy (AES), energy dispersive spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). Elemental composition analysis results can also be calculated based on the results of ion beam time-of-flight secondary ion mass spectroscopy (TOF-SIMS) and Rutherford backscattering spectroscopy (RBS). Of these, elemental composition analysis using X-rays or electron beams is preferred from the perspective of improving diagnostic accuracy. For example, electron probe microanalyzers (EPMA), Auger electron spectroscopy (AES), and X-ray photoelectron spectroscopy (XPS) are preferred. Furthermore, X-ray photoelectron spectroscopy (XPS) is even more preferred from the perspective of improving diagnostic accuracy for the separation membrane.

The XPS analysis of the present invention can be carried out based on the JIS K 0152 standard.

Furthermore, the elemental composition analysis of the present invention can be performed using a general-purpose elemental composition analyzer. For example, KRATOS ULTRA2 (AXIS Supra ⁺ ) or AXIS-ULTRA DLD manufactured by Shimadzu Corporation, JPS-9030 or JPS-9010 manufactured by JEOL Ltd., K-Alpha manufactured by Thermo Fisher Scientific Inc., or PHI5000 VersaPrbeII, PHI GENESIS, PHI Quantes, or PHI Quantera SXM manufactured by ULVAC-PHI, Inc. Analysis software provided with the device can be used to analyze the measurement results.

As mentioned above, the functional layer of a separation membrane is typically thinner than the support layer and substrate. Due to the analytical depth from the sample surface in the aforementioned analytical methods, it is desirable to perform the infrared absorption spectroscopy and elemental composition analysis of this invention by irradiating the functional layer side of the separation membrane with an analytical light source such as infrared light, electron beam, or X-ray. However, it is also possible to physically and/or chemically remove the support layer and substrate before analysis. For example, the substrate of the separation membrane is peeled off, and the membrane is placed on a substrate moistened with an alcohol such as ethanol so that the functional layer surface is in contact with the substrate. The support layer is then removed with an organic solvent such as dichloromethane, and the membrane is irradiated with an analytical light source with the back surface of the functional layer facing up for measurement. The substrate used in this case is not particularly limited, but examples include silicone resin and silicon wafer.

(Diagnostic Method)
In the present invention, it is possible to determine at least one of the presence or absence of a change, the degree of the change, the type of chemical change, and the causative substance in the following manner.

Examples of the degree of change include qualitative classifications such as no change, mild, moderate, and severe, or expressing the degree of change using numbers or symbols.

Examples of chemical changes include oxidation, reduction, and ionization (desorption of hydrogen ions). Examples of causative substances include halogen-based chemicals, as well as radicals such as ozone, hydrogen peroxide, and sulfite radicals generated by the interaction of metal elements with sulfites.

In this invention, halogen-based chemicals refer to chemicals containing hypochlorites such as sodium hypochlorite and calcium hypochlorite, as well as substances produced when hypochlorites react with components in the plant's raw water. Examples include chemicals containing hypobromite, hypoiodite, monochloramine, dichloramine, trichloramine, etc. These halogen-based chemicals are known to cause chemical changes involving halogenation of the constituent materials of the separation membrane.

In particular, the third to seventh embodiments described below are excellent methods for diagnosing at least one of the presence or absence of changes, the degree of change, the type of chemical change, and the causative substance regarding chemical changes in the separation membrane and/or chemical changes in the performance of the separation membrane.

One example of a method for determining chemical changes and/or chemical changes in separation membrane performance in the present invention is a method for determining chemical changes and/or chemical changes in separation membrane performance in either one of the membranes based on the difference between the analysis results of separation membrane 1 and separation membrane 2.

For example, if the analysis result of separation membrane 1 is the analysis result of an unused separation membrane and the analysis result of separation membrane 2 is the analysis result of the target separation membrane, a first form of the present invention is a method for determining chemical changes and/or chemical changes in separation membrane performance, specifically, at least either the presence or absence of a change or the degree of change, based on the difference between the analysis result of the unused separation membrane and the analysis result of the target separation membrane.

In the present invention, an unused separation membrane is one that has not undergone chemical changes, i.e., has not undergone any change in chemical structure, compared to a new separation membrane. For example, even if pure water has been passed through a separation membrane, if no chemical changes have occurred, i.e., no change in chemical structure, it is considered unused. Furthermore, a separation membrane that clearly has not undergone chemical changes and that gives the same analytical results can be said to be unused. In addition to the aforementioned infrared absorption spectroscopy and elemental composition analysis methods, methods for analyzing and/or evaluating changes in chemical structure are used to confirm that a separation membrane is unused, such as nuclear magnetic resonance spectroscopy (NMR).

The analysis results include, for example, the results (numerical values) obtained by performing at least one of the aforementioned infrared absorption spectroscopy and elemental composition analysis.

For example, it is preferable to use one of the following infrared absorption spectroscopy results:

(1) The ratio of the maximum infrared absorption intensity in the first wavenumber range to the maximum infrared absorption intensity in the second wavenumber range including the absorption band originating from the material to be determined for chemical change (2) A predetermined peak wavenumber Note that the peak wavenumber is the wavenumber at which the infrared absorption intensity is maximized in a certain wavenumber range. However, if there is no maximum value of the infrared absorption intensity, the wavenumber at which the infrared absorption intensity is maximized in that wavenumber range may be used instead. For example, a peak wavenumber within the wavenumber range described below is preferred. Furthermore, an absorption band originating from the material to be determined for chemical change is particularly preferred.

(2) When using a specified peak wavenumber, it is desirable to calibrate the instrument using a standard substance, measure the standard substance in parallel, or mix it with the substance to be diagnosed and measure it. Examples of standard substances include polystyrene standard reference samples.

On the other hand, because the absorption intensity of infrared absorption spectroscopy results is affected by the measurement environment and method, when comparing multiple infrared absorption spectroscopy results, i.e., when using the differences, it is preferable to calculate the ratio to the absorption intensity at a certain wavenumber, as this will yield normalized analysis results. From this perspective, it is preferable to use (1) the ratio between the maximum infrared absorption intensity in a first wavenumber range and the maximum infrared absorption intensity in a second wavenumber range that includes the absorption band originating from the material being assessed for chemical change.

The first wavenumber range, the second wavenumber range, and the predetermined peak wavenumber are determined depending on the material of the separation membrane to be diagnosed. For example, when the separation membrane contains polyamide and polysulfone, the first wavenumber range is preferably 1620 to 1600 cm ⁻¹ , 3340 to 3300 cm ⁻¹ , 1260 to 1230 cm ⁻¹ , or any other wavenumber range in which an absorption band derived from polysulfone exists, with 1620 to 1600 cm ⁻¹ , 3340 to 3300 cm ⁻¹ , and 1260 to 1230 cm ⁻¹ being particularly preferred, and 1260 to 1230 cm ⁻¹ being even more preferred. The second wavenumber range is preferably 1680 to 1650 cm ^-1 , 1620 to 1600 cm ^-1 , 1560 to 1530 cm ^-1 , 3340 to 3300 cm ^-1 , or any other wavenumber range in which an absorption band derived from polyamide exists, particularly preferably 1680 to 1650 cm ^-1 , 1620 to 1600 cm ^-1 , 1560 to 1530 cm ^-1 , 3340 to 3300 cm ^-1 , and even more preferably 1680 to 1650 cm ^-1 , 1620 to 1600 cm ^-1 , 1560 to 1530 cm ^-1 . Furthermore, the predetermined peak wavenumber is preferably a peak absorption wavenumber of 1680 to 1650 cm ^-1 , 1620 to 1600 cm ^-1 , or 1560 to 1530 cm ^-1 , and particularly preferably a peak absorption wavenumber of 1680 to 1650 cm ^-1 or 1560 to 1530 ^cm -1 . Here, 1620 to 1600 cm ^-1 , 3340 to 3300 cm ^-1 , 1680 to 1650 cm ^-1 , and 1560 to 1530 cm ^-1 are characteristic absorption bands derived from polyamide, and 1260 to 1230 cm ^-1 is a characteristic absorption band derived from polysulfone. As mentioned above, separation membranes containing polyamide in the separation functional layer and polysulfone in the microporous support layer are common. Therefore, the maximum infrared absorption intensity in the absorption band derived from polyamide and the maximum infrared absorption intensity in the absorption band derived from polysulfone represent the amount and/or density ratio of the separation functional layer to the microporous support layer, and therefore can be used to diagnose the state of the separation membrane.Furthermore, the ratio of the maximum infrared absorption intensities in different absorption bands derived from polyamide represents the state of the separation membrane functional layer, and therefore can be used to diagnose the state of the separation membrane.

Furthermore, when cellulose acetate is contained, the first wavelength range is preferably 2950 to 2920 cm ^-1 , 1440 to 1410 cm ^-1 , 1370 to 1350 cm ^-1 , and 1060 to 1020 cm ^-1 , and particularly preferably 2950 to 2920 cm ^-1 , 1440 to 1410 cm ^-1 , 1370 to 1350 cm ^-1 , and 1060 to 1020 cm ^-1 . Furthermore, the second wavelength range is preferably 1760 to 1740 cm ^-1 and wavenumbers derived from 1170 to 1140 cm ^-1 , and particularly preferably 1170 to 1140 cm ^-1 . These are characteristic absorption bands derived from cellulose acetate, and the ratio of the maximum infrared absorption intensities in these different absorption bands represents the state of the separation membrane functional layer, allowing the state of the separation membrane to be diagnosed.

In addition, the peak wavenumbers of the aforementioned characteristic absorption bands indicate the state of the separation membrane functional layer and microporous support layer, so they can also be used to diagnose the state of the separation membrane.

Furthermore, when other constituent materials are contained, a wavenumber range including an absorption band derived from the other constituent materials and not detected in the material to be subjected to chemical change determination can be arbitrarily selected as the first wavenumber range. In this case, the wavenumber range is preferably within ±40 cm ^-1 of the absorption peak wavenumber, more preferably within ±20 cm ^-1 , and even more preferably within ±10 cm ^-1 .

In addition to the above-mentioned (1) ratio of maximum infrared absorption intensity and (2) predetermined peak wavenumber, the infrared absorption spectroscopy results can also be the peak integral value in the above-mentioned wavenumber range, the average value or median value of infrared absorption intensity, or the average value, etc. That is, the ratio of the peak integral value in the first wavenumber range to the peak integral value in the second wavenumber range including the absorption band originating from the material to be determined for change, the ratio of the average value of infrared absorption intensity in the first wavenumber range to the average value of infrared absorption intensity in the second wavenumber range including the absorption band originating from the material to be determined for change, the ratio of the median value of infrared absorption intensity in the first wavenumber range to the median value of infrared absorption intensity in the second wavenumber range including the absorption band originating from the material to be determined for change, the ratio of the maximum value of infrared absorption intensity in the first wavenumber range to the median value of infrared absorption intensity in the second wavenumber range including the absorption band originating from the material to be determined for change, etc. can also be used. Furthermore, when the wave number showing the maximum infrared absorption intensity in the above-mentioned wave number range is defined as W cm ⁻¹ , the average value of the infrared absorption intensity at W±4 cm ⁻¹ can also be used as the maximum infrared absorption intensity.

The infrared absorption spectroscopy results of the present invention can be used after performing correction processes such as baseline correction and ATR correction to approximate a transmittance spectrum using the aforementioned analysis software. However, it is preferable to perform similar processing on all infrared absorption spectroscopy results, including those used to differentiate analytical results.

In addition, the results of elemental composition analysis can be the elemental composition (atomic %) of a certain element or the composition ratio (%) of other elements based on a certain element.

These analysis results can be obtained from analyzing a single location on the separation membrane being diagnosed, or from multiple locations. In such cases, for example, the average, maximum, median, or weighted average of the analysis results from multiple locations can be calculated and used. Furthermore, when analyzing multiple locations, the differences in the infrared absorption spectroscopy results for each location can be calculated first, and the average, maximum, median, or weighted average of these values can then be calculated and used.

From the perspective of improving the accuracy of diagnostic results, it is preferable to use values calculated from the analysis results of multiple locations, and it is preferable to use either the average, median, or weighted average. In particular, when using infrared absorption spectroscopy results, it is preferable to use results calculated based on the analysis results of four or more locations, and it is even more preferable to use results calculated based on the analysis results of eight or more locations. Furthermore, it is preferable to use values calculated using the same procedure for the analysis results of unused separation membranes and the analysis results of the target separation membranes.

For example, when infrared absorption spectroscopy results are used, measurements are taken at eight locations per separation membrane, and the results at each location are subjected to ATR correction processing and baseline correction based on a linear line created from the absorbance at 4000 and 1800 ^cm . Furthermore, it is desirable to calculate an index of interest, for example, the ratio of the maximum infrared absorption intensity in a first wavenumber range to the maximum infrared absorption intensity in a second wavenumber range that includes the absorption band derived from the material being evaluated for change, for each analysis result, and use the average value of these.

The difference between the analytical results of an unused separation membrane and the analytical results of the target separation membrane is preferably determined using the analytical results of the unused separation membrane and the target separation membrane. However, in this case, the analytical results of the unused separation membrane and the analytical results of the target separation membrane are assumed to have been obtained using the same method. In other words, as mentioned above, for example, the analytical and measurement methods, as well as the calculation methods, are assumed to be the same.

For example, if infrared absorption spectroscopy is performed at eight locations on one unused separation membrane, and for each location, the ratio of the maximum infrared absorption intensity in the first wavenumber range to the maximum infrared absorption intensity in the second wavenumber range including the absorption band due to the material being subjected to change assessment is calculated, and the average value is used as the analysis result of the unused separation membrane, it is preferable to perform infrared absorption spectroscopy at eight locations on one target separation membrane, calculate the ratio of the maximum infrared absorption intensity in the first wavenumber range to the maximum infrared absorption intensity in the second wavenumber range including the absorption band due to the material being subjected to change assessment, and use the average value as the analysis result of the target separation membrane, and use the difference from the analysis result of the unused separation membrane described above to diagnose the condition of the separation membrane.

The difference in analytical results can be, for example, the numerical value (difference, amount of change) obtained by subtracting the analytical result of an unused separation membrane from the analytical result of the target separation membrane, the numerical value (ratio) obtained by dividing the analytical result of the target separation membrane by the analytical result of an unused separation membrane, or the numerical value (rate of change) obtained by dividing the numerical value obtained by subtracting the analytical result of an unused separation membrane from the analytical result of the target separation membrane by the analytical result (numerical value) of an unused separation membrane. In other words, numerical values such as those shown in formulas (1) to (3) can be used.

In this case, the greater the difference between the analytical results of the unused separation membrane and the analytical results of the target separation membrane, the greater the degree of change. For example, with regard to the indicators described below, if the ratio of the analytical results of the target separation membrane to the analytical results of the unused separation membrane is 1.0 or greater, it can be determined that there is no change; if it is 0.9 or greater but less than 1.0, it is determined that there is a slight change; if it is 0.7 or greater but less than 0.9, it is determined that there is a moderate change; and if it is less than 0.7, it is determined that there is a severe change. In this way, it is desirable to determine the numerical criteria to be used for the determination in advance. This numerical criteria can be determined, for example, from the change profile described below or the separation membrane performance when a certain analytical result is obtained. Examples of the numerical criteria are described in the respective embodiments described below.

From the perspective of improving accuracy, a preferred method is to make a comprehensive judgment using the results of multiple analyses. For example, a preferred method is to estimate the degree of change based on the results of the aforementioned infrared absorption spectroscopy, and then determine at least one of the presence or absence of change, the degree of change, the type of chemical change, and the causative substance based on the results of the aforementioned elemental composition analysis and/or the results of infrared absorption spectroscopy.

That is, for example, the degree of change is determined using infrared absorption spectroscopy results focusing on a certain indicator, and this is referred to as the first determination. Furthermore, the presence or absence of change, the degree of change, the type of chemical change, and/or the causative substance are determined using infrared absorption spectroscopy results focusing on an indicator different from that used for the first determination, and this is referred to as the second determination. In this case, the first determination is referred to as an estimation. Here, the indicator of the infrared absorption spectroscopy results is, for example, the ratio of the maximum infrared absorption intensity in the first wavenumber range to the maximum infrared absorption intensity in the second wavenumber range including the absorption band derived from the material being determined for chemical change, or (2) a predetermined peak wavenumber. That is, for example, when the separation membrane contains polyamide and polysulfone, the indicator _RA ÷ _RD can be used. Here, _RA is the maximum infrared absorption intensity at 1680 to 1650 cm ⁻¹ , and _RD is the maximum infrared absorption intensity at 1260 to 1230 cm ⁻¹ .

Examples of such indicators are as described above in the explanation of the analytical method and will also be described in the second and subsequent forms. Hereinafter, infrared absorption spectroscopy results focusing on a certain indicator will also be referred to as infrared absorption spectroscopy results using a certain indicator.

The second determination can also be made using the results of elemental composition analysis. That is, the degree of change is determined as a first determination using the results of infrared absorption spectroscopy using a certain indicator, and then the results of elemental composition analysis focusing on that indicator are used to determine at least one of the presence or absence of change, the degree of change, the type of chemical change, and the causative substance, which constitutes the second determination. In this case, the first determination is called an estimation. Here, the indicator of the results of elemental composition analysis is, for example, the ratio of a certain element to another different element, such as the ratio of halogen elements to oxygen elements. Examples of such indicators are described in the fourth form below.

In addition, the analytical results, indicators, estimation and judgment methods preferably used in each of the above judgments will be described later in the third to fifth forms.

A second method for determining chemical changes and/or chemical changes in the performance of a separation membrane of the present invention involves determining at least the presence or absence of a change or the extent of the change based on the difference between the change profile of analytical results corresponding to the progression of chemical changes and the analytical results of the target separation membrane. As shown in Table 1, while the first method is a qualitative determination, the second method utilizes the correlation between analytical results and an index representing the extent of change, enabling a quantitative determination, thereby improving the reliability and accuracy of diagnostic results. The symbols in Table 1 are as follows:

◯: Determinable △: Determinable but with poor accuracy ×: Impossible to determine or very poor accuracy In the present invention, a profile of changes in the analytical results according to the progress of chemical changes can be obtained, for example, by analyzing separation membranes with different degrees of progress of chemical changes. For example, a profile of changes can be created from the differences in the analytical results of the separation membranes when the separation membranes are exposed to a halogen-based agent in a preliminary experiment and the amount of halogen contact (immersion solution concentration [mg/L] x time [h]) is changed.

The method for contacting the separation membrane with the halogen-based chemical is not particularly limited, but examples include immersing the separation membrane in a chemical solution containing the halogen-based chemical, or passing the chemical solution through the separation membrane. The chemical solution used in this case is preferably an aqueous solution containing not only the halogen-based chemical but also chloride ions and/or bromide ions.

In this case, it is preferable to use the analytical results of an unused separation membrane as a reference and create a change profile using the difference between the analytical results of an unused separation membrane and the analytical results of a separation membrane that has undergone chemical change. As with the first embodiment, the difference can be a difference, a ratio, a rate of change, or the like. Also, as with the first embodiment, correction processing or the average, median, maximum, or weighted average of the analytical results for multiple locations can be used. However, as with the first embodiment, if the aforementioned correction processing or a specified unambiguous calculation is performed on the analytical results, it is preferable to perform the same correction processing or calculation on the analytical results of all separation membranes with different degrees of chemical change to create a change profile. From the perspective of improving the accuracy of diagnostic results, it is preferable to use values calculated from the analytical results of multiple locations. In particular, when infrared absorption spectroscopy results are used, it is preferable to use the average, median, or weighted average calculated from the analytical results of eight or more locations.

One method for creating a change profile is to create a regression equation using the least squares method based on the correlation between the analytical results of separation membranes with different degrees of chemical change and an index representing the separation membrane performance, as shown in Figure 2. Another method is to create a regression equation using the least squares method based on the correlation between the difference between the analytical results of separation membranes with different degrees of chemical change and an unused separation membrane and the difference in an index representing separation membrane performance. In this case, the index representing separation membrane performance can be a general index representing the degree of solute removal, permeation, or separation selectivity of solutes and/or solutes, which are permeable substances through a separation membrane. Examples include, but are not limited to, solute rejection rate, solute permeability rate, solvent permeability coefficient, solute permeability coefficient, solvent permeation volume, and solute permeation volume. Furthermore, as described above, it is desirable to include unused separation membranes as separation membranes with different degrees of chemical change, and it is preferable to use the difference in analytical results relative to an unused separation membrane, as described above. The form of the regression equation can be any form, such as a linear line, a quadratic curve, an exponential function, or a logarithmic function, depending on the correlation between the analysis results and the index representing the separation membrane performance.

Examples of methods for calculating the aforementioned separation membrane performance include the following methods for calculating solvent permeability coefficient and solute permeability coefficient.

The permeating substances in a separation membrane consist of a solvent and a solute. The solvent permeates the reverse osmosis membrane due to a pressure difference, and the solute permeates the reverse osmosis membrane due to a concentration difference. As shown in equation (4), the solvent permeation flux Jv is expressed as the product of the solvent permeability coefficient Lp specific to the reverse osmosis membrane and the effective pressure difference ΔPe. Also, as shown in equation (5), the solute permeation flux Js is expressed as the product of the solute permeability coefficient P specific to the reverse osmosis membrane and the transmembrane concentration difference (Cm - Cp).

Here, Cm is the solute concentration on the membrane surface on the treated liquid side, Cp is the solute concentration in the treated liquid, Cs is the average solute concentration, π(C) is the osmotic pressure at concentration C, and σ is the reflectance.

Here, it is assumed that a membrane with high salt rejection is used, the reflectance σ is very close to 1, and the solvent permeation flux _Jv and the solute permeation flux _Js are given by equations (6) and (7).

Also, Cp is given by equation (8).

When determining the solute concentration Cm on the membrane surface on the treated liquid side, it is desirable to take into account the concentration polarization phenomenon (the phenomenon in which the salt concentration on the membrane surface on the treated liquid side becomes higher than the salt concentration in the bulk of the treated liquid due to the accumulation of solutes on the membrane surface).

This concentration polarization phenomenon can be expressed by the following equation (9) using three mass balance equations: the movement of solute accompanying the solvent permeation flux, Jv·C; the diffusion of solute on the membrane surface on the treated liquid side, D _C ·dC/dx; and the amount of solute that has permeated the membrane, _Jv ·C _p .

where D _C is the diffusion coefficient of the solute. By integrating the mass balance equation (9), we obtain the concentration polarization equation (10).

Here, k=D _C /δ, where k is the mass transfer coefficient and δ is the thickness of the layer through which mass transfer takes place.

The mass transfer coefficient k can be calculated, for example, as follows:

The mass transfer correlation (Sh = a Reb Scc) is an equation that shows the flow characteristics of reverse osmosis membrane applications (e.g., spiral-wound reverse osmosis membrane elements) and expresses the relationship between the Sherwood number (Nusselt number) Sh, the Reynolds number Re, and the Schmidt number Sc. The Sherwood number Sh is a dimensionless quantity obtained by dividing the product of the mass transfer coefficient k and the flow path thickness d of the layer where mass transfer occurs by the solute diffusion coefficient DC, and expresses the ease of solute movement. The Reynolds number Re is obtained by dividing the product of the flow velocity u, density ρ, and characteristic length d of the treated liquid by the viscosity coefficient η, and expresses the influence of the treated liquid's flow velocity. The Schmidt number Sc is obtained by dividing the viscosity coefficient η by the product of the density ρ and solute diffusion coefficient DC, and expresses the influence of the treated liquid's physical properties.

In this embodiment, the exponents b and c of the Reynolds number Re and the Schmidt number Sc in the mass transfer correlation equation are set to predetermined fixed values. For example, in accordance with the Deissler equation, which is known as a mass transfer correlation equation for piping, the exponents b and c are set to, for example, 0.875 and 0.25, respectively.

In this case, the mass transfer correlation equation is equation (14), and equation (15) is obtained from equations (11) and (14).

Here, the unknown coefficient a in equation (15) can be determined by conducting experiments in which the flow rate u of the treated liquid is changed depending on the usage pattern of the reverse osmosis membrane.

It is known that the solvent permeability coefficient Lp and solute permeability coefficient P, which are specific to reverse osmosis membranes, change reversibly due to the influence of temperature, pressure, etc. Any method can be used to correct the reversible changes, but for example, if the changed solvent permeability coefficient and solute permeability coefficient are Lp' and P', respectively, the viscosity of the treated liquid is μ, the viscosity of the treated liquid at 25°C is μ ₂₅ , the temperature of the treated liquid is Tf, the pressure of the treated liquid is Pf, the standard operating pressure (for example, the standard operating pressure listed in the product catalog) is Ps, and constants specific to each membrane type are c ₁ , c ₂ , d ₁ , and d ₂ , then the reversible changes can be determined by the following equations (16) and (17):

In this way, the solvent permeation flux Jv and solute permeation flux Js can be calculated. In other words, if the values of the treated liquid flow rate Qf, treated liquid flow rate Qp, membrane area A, solute concentration of the treated liquid Cf, solute concentration of the treated liquid Cp, pressure of the treated liquid Pf, standard operating pressure Ps, and temperature of the treated liquid Tf are known in advance, Jv and Js can be calculated backward from these values, and Lp and P that satisfy Jv and Js can be determined.

As an example of the second embodiment, as shown in Figure 3, in advance, four separation membranes were contacted in an experiment with a halogen-based agent of a specified concentration for different immersion times, and analysis and separation membrane performance evaluation were carried out. The difference (X - X ₁ ) between the analysis result X of the unused separation membrane and the analysis result X of the separation membrane in which the change had progressed, and the ratio (Y ÷ Y ₁ ) of the solvent permeability coefficient Y of the unused separation membrane to the solvent permeability coefficient Y of the separation membrane in which the change had progressed were used to create a change profile 1 regarding the analysis results according to the progress of the change. The difference (X ₂ - X ₁ ) between the analysis result X ₂ of the target separation membrane and _the analysis result of the unused separation membrane was compared with the change profile 1, that is, the state of the target separation membrane was diagnosed based on Y ₂ when X = X ₂ - X ₁ in the change profile 1. At this time, Y ₂ represents the ratio to the solvent permeability coefficient of the unused separation membrane, so regarding the presence or absence of a chemical change, if Y ₂ is 1.0, it is determined that there is no change, and otherwise it is determined that there is a change. Furthermore, when determining the degree of chemical change, if _Y2 is large, the change can be determined to be large, and if _Y2 is small, the change can be determined to be small. For example, if _Y2 is 1.5 or less, the change is determined to be mild, if it is greater than 1.5 and less than 3, the change is determined to be moderate, and if it is greater than 3, the change is determined to be severe.

As another example, when a change profile is created using the ratio (X÷ _X1 ) as the difference in analysis results, the determination can be made using the value on the vertical axis when the ratio ( _X3 ÷ _X1 ) between the analysis results _X3 and _X1 of the target separation membrane is taken as the value on the horizontal axis in the change profile. As yet another example, when a change profile is created using the rate of change (1-X÷ _X1 ) as the difference in analysis results, the determination can be made using the value on the vertical axis when the rate of change (1- _X3 ÷ _X1 ) between the analysis results _X3 and _X1 of the target separation membrane is taken as the value on the horizontal axis.

In this way, when determining the chemical change of the target separation membrane based on the difference between the change profile regarding the analytical results corresponding to the chemical change and the analytical results of the target separation membrane, the analytical results of the target separation membrane are, as in the first form, values obtained using the same analytical method, indicators, and calculation method as when creating the change profile.

For example, when creating a change profile using infrared absorption spectroscopy, if the ratio of the maximum infrared absorption intensity in a first wavenumber range to the maximum infrared absorption intensity in a second wavenumber range including the absorption band attributable to the material being assessed for change is used, then the ratio of the maximum infrared absorption intensity in the first wavenumber range to the maximum infrared absorption intensity in the second wavenumber range including the absorption band attributable to the material being assessed for change is also used as the analysis result for the target separation membrane. Furthermore, for example, if a profile relating to the analysis results in response to chemical change is created using the analysis results for an unused separation membrane as the reference and the analysis results for an unused separation membrane and a separation membrane in which a chemical change has progressed, a similar difference, i.e., the analysis results for an unused separation membrane as the reference and the difference between the analysis results for the unused separation membrane and the analysis results for the target separation membrane, is used as the analysis result for the target separation membrane to be compared with the change profile relating to the analysis results in response to chemical change.

Furthermore, as in the first embodiment, when performing the aforementioned correction processing or prescribed unique calculations on the analytical results, or when using a change profile created using values calculated from the results of analyses at multiple locations, the analytical results for the target separation membrane are also obtained using results obtained in the same manner. From the perspective of improving the accuracy of diagnostic results, it is preferable to use values calculated from the results of analyses at multiple locations. In particular, when using infrared absorption spectroscopy results, it is preferable to use the average, median, or weighted average calculated based on the results of analyses at eight or more locations.

A third embodiment of the present invention for determining chemical changes and/or chemical changes in the performance of a separation membrane includes a method in which, in the first or second embodiment described above, the separation membrane contains polyamide and polysulfone, and at least either the presence or absence of a change or the degree of the change is determined based on a difference in at least one of the following indicators (1) to (9) in the results of infrared absorption spectroscopy of the separation membrane.
(1) R _A ÷ R _D
(2) R _B ÷ R _D
(3) R _C ÷ R _D
(4) R _E ÷ R _D
(5) R _A ÷ R _B
(6) R _C ÷ R _B
(7) R _A ÷ R _E
(8) Peak wave number in the range of 1680 to 1650 cm ⁻¹ (9) Peak wave number in the range of 1560 to 1530 cm ⁻¹ (wherein R _A is the maximum infrared absorption intensity in the range of 1680 to 1650 cm ⁻¹ , R _B is the maximum infrared absorption intensity in the range of 1620 to 1600 cm ⁻¹ , R _C is the maximum infrared absorption intensity in the range of 1560 to 1530 cm ⁻¹ , R _D is the maximum infrared absorption intensity in the range of 1260 to 1230 cm ⁻¹ , and R _E is the maximum infrared absorption intensity in the range of 3340 to 3300 cm ⁻¹ .)
As described above, R _{A ,} R _{B ,} R _{C , and} R _E are the maximum infrared absorption intensities of the characteristic absorption bands derived from polyamide, and R _D is the maximum infrared absorption intensities of the characteristic absorption bands derived from polysulfone. Furthermore, 1680 to 1650 cm ⁻¹ and 1560 to 1530 cm ⁻¹ are characteristic absorption bands derived from polyamide. Therefore, as described above, the maximum infrared absorption intensities in the absorption bands derived from polyamide and the maximum infrared absorption intensities in the absorption bands derived from polysulfone represent the amount and/or density ratio of the separation functional layer to the microporous support layer, and therefore can be used to diagnose the state of the separation membrane. Furthermore, the ratio of the maximum infrared absorption intensities in different absorption bands derived from polyamide represents the state of the separation membrane functional layer, and therefore can be used to diagnose the state of the separation membrane. Furthermore, the peak wavenumbers of the aforementioned characteristic absorption bands represent the state of the separation membrane functional layer and the microporous support layer, and therefore can also be used to diagnose the state of the separation membrane.

Which of these indicators to use can be selected at will, but as an example, preferred indicators can be used depending on the degree of expected change, as shown in Table 2. Note that for each change, whether it is present or absent, its degree, or whether it is qualitative or quantitative, the larger the number in Table 2, the higher the accuracy and the more preferably it is used. The overall evaluation is the sum of each score.

If results differ using indicators with similar accuracy, the result showing the greatest degree of change should be used. On the other hand, if the presence or absence of change, the degree of change, the type of chemical change, or the causative substance can be estimated, it is preferable to determine which result to use based on the scores in Table 2, as described above.

As another example, it is possible to use multiple different indicators to make a judgment and compare the results to confirm the reliability of the judgment results. In this case, if different judgment results are obtained depending on the indicator used, it is preferable to adopt the result using the indicator with the higher accuracy, as shown in Table 2, depending on the expected degree of change and whether qualitative or quantitative judgment is required. If different judgment results are obtained using indicators with similar accuracy, it is preferable to adopt the result that matches more indicators. Alternatively, if the expected degree of change is unknown, it is preferable to adopt the result using the indicator with the highest overall evaluation. Here, cases where the degree of change is unknown include cases where it is unclear whether a change has occurred or the degree of change is unknown, i.e., whether it is mild, moderate, or severe. On the other hand, when the degree of change is expected, such as when a judgment method or means other than those described in this invention is used, such as when a large amount of a substance that clearly deteriorates the separation membrane is detected in the feedwater to a separation membrane filtration unit of a plant using separation membranes, it is preferable to follow the indicators listed in Table 2 above.

In particular, from the viewpoint of improving the accuracy of diagnostic results and widening the range of application, it is preferable to use any of (1) R _A ÷ R _D , (2) R _B ÷ R _D , (3) R _C ÷ R _D , (4) R _E ÷ R _D , (8) the peak wavenumber at 1680 to 1650 cm ⁻¹ , and (9) the peak wavenumber at 1560 to 1530 cm ⁻¹ , and it is more preferable to use (1) R _A ÷ R _D or (2) R _B ÷ R _D , and it is particularly preferable to use (1) R _A ÷ R _D.

Alternatively, an example of a method using multiple different indicators is to estimate the degree of change from the analytical results of one indicator, and then determine the presence or absence of change, the degree of change, the type of chemical change, and/or the causative substance based on the analytical results of another indicator.

In this case, for example, the index used to estimate the degree of change can be selected based on the expected degree of change and the score shown in Table 2, as described above. Furthermore, as described above, at least one of the presence or absence of change, the degree of change, the type of chemical change, and the causative substance can be determined based on the score shown in Table 2. In particular, from the viewpoint of improving the accuracy of diagnostic results as described above, it is preferable to use any of the following indices for estimation: (1) R _A ÷ R _D , (2) R _B ÷ R _D , (3) R _C ÷ R _D , (4) R _E ÷ R _D , (8) the peak wavenumber at 1680 to 1650 cm ⁻¹ , and (9) the peak wavenumber at 1560 to 1530 cm ⁻¹ , and it is more preferable to use (1) R _A ÷ R _D or (2) R _B ÷ R _D , and it is particularly preferable to use (1) R _A ÷ R _D .

Furthermore, when determining at least one of the type of chemical change and the causative substance, it is preferable to use the infrared absorption spectroscopy results for either (2) R _B ÷ R _D or (4) R _E ÷ R _D in the method described in the fifth embodiment described below, instead of the fourth embodiment using the elemental composition analysis results, and it is particularly preferable to use (2) R _B ÷ R _D.

When using the above indicators, from the perspective of analytical accuracy, it is preferable to use the ratio or rate of change of the indicators when the ratio of the maximum infrared absorption intensity in the first wavenumber range to the maximum infrared absorption intensity in the second wavenumber range that includes the absorption band derived from the material being assessed for chemical change is used as the indicator, as in (1) to (7), or the difference of the indicators when a specified peak wavenumber is used as the indicator, as in (8) or (9).

For example, when (1) _RA ÷ _RD is used as an index, if the ratio of the analysis result (value) of the target separation membrane to the analysis result (value) of the index of the unused separation membrane is 1.0 or more, it is determined that there is no change, and if it is less than 1.0, it is determined that there is a change. Alternatively, if the rate of change of the analysis result (value) of the target separation membrane to the analysis result (value) of the index of the unused separation membrane is 0 or less, it is determined that there is no change, and if it exceeds 0, it is determined that there is a change. Furthermore, for example, when determining the degree of change, if the ratio of the analysis result of the target separation membrane to the analysis result of the index of the unused separation membrane is 0.9 or more and less than 1.0, it is determined as mild, if it is 0.8 or more and less than 0.9, it is determined as moderate, and if it is less than 0.8, it is determined as severe. Alternatively, if the rate of change of the analysis result (value) of the target separation membrane to the analysis result (value) of the index of the unused separation membrane is more than 0 and less than 0.1, it is determined as mild, if it is more than 0.1 and less than 0.2, it is determined as moderate, and if it is more than 0.2, it is determined as severe.

As in the fourth embodiment described below, it is also possible to determine chemical changes and/or chemical changes in the performance of the target separation membrane based on the difference between the change profile of the infrared absorption spectroscopy results corresponding to chemical changes and the infrared absorption spectroscopy results of the target separation membrane. It is also preferable to use in advance, from the change profile, the numerical criteria to be used for the aforementioned determination.

As with the first embodiment, when performing the aforementioned correction processing or a specified unambiguous calculation on the analysis results, or when using a change profile created using values calculated from the results of analysis at multiple locations, the analysis results for the target separation membrane are also obtained using the results obtained in the same manner. From the perspective of improving the accuracy of the diagnostic results, it is preferable to use values calculated from the results of analysis at multiple locations. In particular, when using infrared absorption spectroscopy results, it is preferable to use the average, median, or weighted average calculated based on the results of analysis at eight or more locations.

A fourth embodiment of the present invention for determining chemical changes and/or chemical changes in the performance of the separation membrane includes a method in the first or second embodiment described above, in which the presence or absence of a change or the degree of the change is determined based on a difference in at least one of the following indicators (1) to (3) in the results of elemental composition analysis of the separation membrane:
(1) Ratio of halogen elements to carbon elements (2) Ratio of oxygen elements to carbon elements (3) Ratio of nitrogen elements to carbon elements While any of these indices can be used, as an example, preferred indices can be used depending on the expected degree of chemical change as shown in Table 2. Note that the larger the value shown in Table 2, the more preferably the indices can be used in the case of the change range.

Which of these indices to use can be selected at will, but as an example, preferred indices can be used depending on the degree of expected change, as shown in Table 2. Note that the larger the value in Table 2, the higher the accuracy and the more preferred it is to use.

As with the third embodiment, as another example, it is possible to use multiple different indicators to make a judgment and compare the results to confirm the reliability of the judgment results. In this case, if different judgment results are obtained depending on the indicator used, it is preferable to adopt the result using the indicator with the highest accuracy in terms of the expected degree of chemical change, as shown in Table 2. If different judgment results are obtained using indicators with similar accuracy, it is preferable to adopt the result that matches more indicators. Alternatively, if the expected degree of change is unknown, it is preferable to adopt the result using the indicator with the highest overall evaluation.

When using the above indicators, it is preferable to use the difference in the analysis results in the case of (1) the ratio of halogen elements to carbon elements as the difference, and in other cases as the ratio or rate of change, from the standpoint of analytical accuracy.

For example, if the ratio of halogen elements to carbon elements in the analysis results of an unused separation membrane is 0 (zero), then if the ratio of halogen elements to carbon elements in the analysis results of the target separation membrane is 0.001 or less, it is determined that there is no change, and if it is greater than 0.001, it is determined that there is a change. Furthermore, when determining the degree of chemical change in cases where the ratio of halogen elements to carbon elements in the analysis results of an unused separation membrane is 0 (zero), the degree can be qualitatively determined as mild if the ratio of halogen elements to carbon elements in the analysis results of the target separation membrane is 0.01 or more and 0.040 or less, moderate if greater than 0.040 and 0.080 or less, and severe if greater than 0.080.

As another example, as shown in FIG. 4, five separation membranes are previously exposed to a halogen-based agent of a specified concentration for different immersion times in an experiment, and a change profile relating to the analysis results according to the progress of change is created using the difference (X- _X3 ) between the ratio _X of halogen elements to carbon elements in the analysis results of each separation membrane and the ratio _X3 of halogen elements to carbon elements in the elemental composition analysis results of an unused separation membrane, and the ratio (Y÷ _Y3 ) between the solvent permeability coefficient _Y3 of the unused separation membrane and the solvent permeability coefficient _Y3 of each separation membrane in which change has progressed. Then, a judgment is made based on the result of comparing the difference ( _X4 - _X3 ) between the ratio X3 of halogen elements to carbon elements in the analysis results of the target separation membrane and the ratio _X4 of halogen elements to carbon elements in the analysis results of an unused separation membrane with the change profile, that is, _Y4 when X = _X4 - _X3 in the change profile. In this case, _Y4 represents the ratio to the solvent permeability coefficient of an unused separation membrane, so that if _Y4 is 1.0, it is determined that there is no change, and if it is any other value, it is determined that there is a change. Furthermore, for example, when determining the degree of change, since Y is the solvent permeability coefficient of the separation membrane, if _Y4 is 1.0 or more and less than 1.5, it is determined as slight, if it is more than 1.5 and less than 3.0, it is determined as moderate, and if it is more than 3.0, it is determined as severe.

As with the first to third embodiments, when performing the aforementioned correction processing or prescribed unambiguous calculations on the analysis results, it is preferable to perform the same correction processing or calculations on all analysis results for separation membranes with different degrees of chemical change to create a change profile. From the perspective of improving the accuracy of diagnostic results, it is preferable to use values calculated from analysis results at multiple locations. In particular, when using infrared absorption spectroscopy results, it is preferable to use the average, median, or weighted average calculated from analysis results at eight or more locations.

Either the third or fourth form is more preferable when determining at least the presence or absence of change and the degree of change. In particular, the third form utilizes infrared absorption spectroscopy, which is simple to operate and can obtain functional group information, making it preferable from the perspective of ease of analytical operation and range of application. On the other hand, the fourth form is preferable when determining minor chemical changes caused by halogen-based oxidizing agents or when strictly determining the presence or absence of change (impact) caused by halogen-based agents, and (1) using the ratio of halogen elements to carbon elements is particularly preferable. In particular, using highly sensitive elemental composition analysis such as photoelectron spectroscopy (XPS) or a method that can obtain elemental composition information of the surface layer enables more precise condition diagnosis.

A fifth embodiment is a method in which the degree of change is estimated using the third embodiment, and then the fourth embodiment is used to determine at least one of the presence or absence of change, the degree of change, the type of chemical change, and the causative substance. That is, the degree of change is estimated using the infrared absorption spectroscopy results described in the third embodiment, and then the presence or absence of change, the degree of change, the type of chemical change, and the causative substance are determined using the elemental composition analysis results described in the fourth embodiment.

The fifth form is preferable from the standpoint of more accurately determining whether or not there is a change and the extent of the change, as shown in Table 3.

As the fourth form (elemental composition analysis results) used in the fifth form, (1) the ratio of halogen elements to carbon elements is preferably used for changes caused by halogen-based drugs, and (2) the ratio of oxygen elements to carbon elements is preferably used for changes caused by factors other than halogen-based drugs. Furthermore, as for the third form (infrared absorption spectroscopy), as mentioned above, from the viewpoint of improving the accuracy of diagnostic results and widening the range of application, it is preferable to use any of (1) R _A ÷ R _D , (2) R _B ÷ R _D , (3) R _C ÷ R _D , (4) R _E ÷ R _D , (8) the peak wavenumber at 1680 to 1650 cm ⁻¹ , and (9) the peak wavenumber at 1560 to 1530 cm ⁻¹ , and it is more preferable to use (1) R _A ÷ R _D or (2) R _B ÷ R _D , and it is particularly preferable to use (1) R _A ÷ R _D .

In particular, as shown in Table 2, when the degree of change is unknown or when the degree of change is severe, it is preferable to use (1) R _A ÷ R _D or (2) R _B ÷ R _D , and it is particularly preferable to use (1) R _A ÷ R _D.

In the fifth form, by using both the infrared absorption spectroscopy results and the elemental composition analysis results, it is possible to determine the type of chemical change and the causative substance. The symbols in Table 3 are as follows:

◎: Determinable and highly accurate 〇: Determinable △: Determinable but with poor accuracy ×: Cannot be determined or with very poor accuracy If a result different from the estimated result is obtained regarding the degree of change, the result with the greater degree of change or the result using the index with the highest accuracy according to the scores in Table 2 as described above will be used.

If results differ using indicators with similar accuracy, the result showing the greatest degree of change should be used. On the other hand, if the presence or absence of change, the degree of change, the type of chemical change, or the causative substance can be estimated, it is preferable to determine which result to use based on the scores in Table 2, as described above.

For example, when using the rate of change of R _A ÷ R _D , the score listed in the row for R _A ÷ R _D in Table 2 is referenced. In this case, for example, if the presence or absence of change and the degree of change are unknown, using the rate of change of R _A ÷ R _D (the ratio of 1-R _A ÷ R _D ) from the overall evaluation score listed in Table 2 will result in 21 points. In contrast, with R _B ÷ R _D or R _C ÷ R _D , the overall score is 15 points, which is lower than 21 points. Therefore, when the presence or absence of change and the degree of change are unknown, it is desirable from the standpoint of _{accuracy to adopt the result of the rate of change of R A ÷ R D (the ratio of 1-R A ÷ R D ) rather than the} rate of change of R _B ÷ R _D or R C ÷ R D (the ratio of 1-R _B ÷ R D or the ratio of 1-R C ÷ R _D ).

For example, (1) with respect to the ratio of halogen elements to carbon elements, if the difference between the analysis results of an unused membrane and the analysis results of the target separation membrane is greater than 0.001, it is determined that there has been a change. In this case, it is determined that a halogen-based agent is the cause. On the other hand, (1) with respect to the ratio of halogen elements to carbon elements, even if the difference between the analysis results of an unused membrane and the analysis results of the target separation membrane is 0.001 or less, if a change is diagnosed using the third method, it is determined that there has been a change, and the degree of chemical change is determined using the third method. On the other hand, if the difference between the analysis results of an unused membrane and the analysis results of the target separation membrane is 0.001 or less, and no change is diagnosed using the third method, it is determined that there has been no change.

On the other hand, if the use history of the control separation membrane suggests that the change is a minor chemical change caused by a halogen-based oxidizing agent, the fourth form of halogen to carbon ratio is the most suitable, with the highest score for minor changes in Table 2. In this case, if the difference between the analytical results of the unused membrane and the target separation membrane in terms of (1) the halogen to carbon ratio is 0.001 or less, indicating no change, then even if a change is determined to have occurred in the third form, it is still determined to be no change because (1) the halogen to carbon ratio is considered to be a more suitable indicator.

A sixth form of determining chemical changes and/or chemical changes in separation membrane performance of the separation membrane of the present invention is a method in which, as shown in Figures 5 and 6, a change profile is created between at least one of the removal rate, solute permeability coefficient, and solvent permeation amount and the analysis results, the analysis results being infrared absorption spectroscopy results and elemental composition analysis results, the target separation membrane performance _S1 is calculated from the difference between the change profile related to the analysis results and the infrared absorption spectroscopy results of the target separation membrane, the target separation membrane performance _S2 is calculated from the difference between the change profile related to the analysis results and the elemental composition analysis results of the target separation membrane, and the type of chemical change and/or the causative substance is determined from the difference between _S1 and _S2 .

That is, as shown in Table 3, by combining the results of infrared absorption spectroscopy and elemental composition analysis, it is possible to estimate the type of chemical change and the causative substance. Furthermore, the type of chemical change and the causative substance can be diagnosed through quantitative comparison using at least one of the removal rate, solute permeability coefficient, and solvent permeation amount. However, when using this method, it is necessary to confirm that the degree of change is not "severe," that is, the degree of change is "mild" or "moderate."

In this case, as in the second embodiment, the same indicators as used when creating the change profile are used as the analysis results of the target separation membrane. Furthermore, it is preferable to use the analysis results of an unused separation membrane as a reference to create a change profile related to the analysis results, and to use the difference between the analysis results of the unused separation membrane and the analysis results of the target separation membrane when calculating the target separation membrane performances _S1 and _S2 . Furthermore, as in the first embodiment, when performing the correction processing or prescribed unambiguous calculation as described above on the analysis results, it is preferable to perform the same correction processing or calculation on all analysis results of separation membranes with different degrees of chemical change to create a change profile. From the viewpoint of improving the accuracy of the diagnostic results, it is preferable to use values calculated from the analysis results of multiple locations, and particularly when using infrared absorption spectroscopy results, it is preferable to use the average, median, or weighted average calculated based on the analysis results of eight or more locations.

As the result of elemental composition analysis, it is preferable to use (1) the ratio of halogen elements to carbon elements or (3) the ratio of nitrogen elements to carbon elements, and it is particularly preferable to use (1) the ratio of halogen elements to carbon elements. As the result of infrared absorption spectroscopy, it is preferable to use any of (1) R _A ÷ R _D , (2) R _B ÷ R _D , (3) R _C ÷ R _D , (4) R _E ÷ R _D , (7) R _A ÷ R _{E ,} (8) the peak wave number at 1680 to 1650 cm ⁻¹ , and (9) the peak wave number at 1560 to 1530 cm ⁻¹ , and it is more preferable to use (1) R _A ÷ R _D or (2) R _B ÷ R _D , and it is particularly preferable to use (1) R _A ÷ R _D.

When using the above indexes, it is preferable to use the ratio or rate of change when using any of (2) the ratio of oxygen element to carbon element, (3) the ratio of oxygen element to carbon element, (1) R _A ÷ R _D , (2) R _B ÷ R _D , (3) R _C ÷ R _D , (4) R _E ÷ R _D , (7) R _A ÷ R _E as the difference in the analysis results from the viewpoint of analytical accuracy, and to use the difference in other cases.

That is, it is particularly preferable to use (1) the difference in the ratio of halogen elements to carbon elements as the elemental composition analysis result, and (1) the ratio or rate of change of R _A ÷R _D as the infrared absorption spectroscopy result.

As a method for determining the causative substance, for example, (1) the degree of change is determined from the ratio or rate of change of R _A ÷ R _D , as in the third embodiment, and if it is determined to be mild or moderate, for example, (1) the ratio _Sr1 of the solute permeability coefficient of the target separation membrane to that of an unused separation membrane calculated using the ratio or rate of change of R _A ÷ R _D , and (1) the ratio Sr2 of the solute permeability coefficient of the target separation membrane to that of an unused separation membrane estimated using the difference in the ratio of halogen elements to carbon elements, if the difference between _Sr1 and _Sr2 is small, the causative substance is determined to be a halogen-based agent, and if it is large _, it is determined to be something other than a halogen-based agent. That is, for example, if the ratio _Sr1 of the solute permeability coefficient of the target separation membrane to that of an unused separation membrane calculated using the ratio or rate of change of (1) R _A ÷ R _D is three times or less ( _Sr1 ÷ Sr2 _≦ 3) the ratio _Sr2 of the solute permeability coefficient of the target separation membrane to that of an unused separation membrane estimated using the difference in the ratio of halogen elements to carbon elements, the causative substance is determined to be a halogen-based agent, and if it is more than three times ( _Sr1 ÷ _Sr2 > 3), the causative substance is determined to be something other than a halogen-based agent. However, if the degree of change is severe, _Sr1 ÷ _Sr2 may be > 3 even if a halogen-based agent is the causative substance.

As such, a seventh embodiment of the present invention for determining chemical changes and/or chemical changes in the performance of a separation membrane involves using the third embodiment to determine at least the presence or absence of a change or the degree of change, and then using the fifth embodiment to determine the causative substance. This embodiment is particularly preferred when the degree of change is unknown. Furthermore, it is even more preferred to implement the fifth embodiment after implementing the seventh embodiment to improve the reliability and accuracy of the results.

Any of these forms can be selected depending on the usage and purpose of the target separation membrane.

(Usage example)
As an example of the use of the present invention, by using a separation membrane installed in a water treatment plant, for example, a membrane collected from a separation membrane element installed in a separation membrane filtration unit 5, as the target separation membrane of the present invention, it becomes possible to diagnose the condition of the separation membrane in the water treatment plant.

As mentioned above, when a separation membrane in a component installed in a plant piping system is used as the target separation membrane of the present invention, it is possible to determine at least one of the risk of chemical reactions, the type of chemical reaction, and the substance causing the chemical reaction in an actual plant. Furthermore, by conducting this test periodically, for example, regularly, for example, once a day to once a week, it becomes easier to identify the timing of any sudden increases in the risk of chemical reactions, enabling prompt countermeasures to be implemented. In this case, if it is difficult to extract a separation membrane from an installation component of the separation membrane filtration unit, such as a separation membrane element, it is desirable to use a separation membrane installed in a piping close to the separation membrane filtration unit, such as the separation membrane filtration feed water piping 10, the separation membrane filtration permeate piping 11, or the separation membrane filtration concentrate piping 12, because this allows for accurate and rapid evaluation of the risk of chemical reactions occurring in the separation membrane filtration unit 5. An example of how the separation membrane can be installed in the piping is to install a water-permeable component containing a separation membrane within the piping.

The water-permeable member of the present invention is not particularly limited as long as it contains a separation membrane and allows a solution to move from one end of the water-permeable member to the other. Furthermore, as mentioned above, to prevent the risk of chemical changes occurring periodically and frequently, it is desirable for the water-permeable member to be easily attached and detached to the piping of a water treatment plant. For example, it is desirable for certain unit structures to be continuously connected and detached via connecting members such as threaded or interlocking structures (such as joints), or for the structure to be easily cut or partially separable using scissors, such as a hose. As an example, as illustrated in Figures 7 and 8, a preferred form of water-permeable container 19 can be formed by connecting one or more unit water-permeable members 19a, each of which has a cylindrical shape, threaded grooves on both ends in the longitudinal direction (water flow direction), and a connectable structure in which a separation membrane 20 is installed perpendicular to the water flow direction. It is preferable to provide water leakage prevention measures, such as packing, sealing tape, or O-rings, at the connecting portions depending on the shape. In this case, the area of the separation membrane 20 is not particularly limited, but is preferably 0.01 m ² or more, and more preferably 0.03 m ² or more.

A simple water-passing container can be a hose or similar material. In this case, it is preferable that the water-passing container be cylindrical and made of a soft material. This makes it easy to cut it with scissors or the like and remove the separation membrane inside.

In addition, if the water-permeable member is installed on piping within the plant other than near the separation membrane filtration unit as mentioned above, it is also possible to evaluate the risk of chemical changes in each piping and its vicinity.

That is, examples of the separation membrane of the present invention include the following.
A: Separation membrane collected from a semipermeable membrane element that separates feed water into permeate and concentrate at a water treatment plant. B: Separation membrane installed inside a water-permeable member installed in a feed water line at a water treatment plant. C: Separation membrane installed inside a water-permeable member installed in a concentrate line at a water treatment plant, where a semipermeable membrane element that separates feed water into permeate and concentrate is used. (Diagnostic program, evaluation device, recording medium)
Another embodiment of the present invention is a separation membrane condition diagnosis program that causes a computer to function as a data input means for inputting separation membrane analysis results into the computer, and a condition diagnosis means for determining the state of a separation membrane based on the difference between the analysis results of separation membrane 1 and the analysis results of separation membrane 2, and for determining chemical changes and/or chemical changes in separation membrane performance. This embodiment causes a computer having each of these means to function to diagnose the state of the separation membrane. This embodiment can be recorded in a recording device such as the computer's memory or a hard disk, and the recording format is not particularly limited. Another embodiment of the present invention is a recording medium on which the separation membrane condition diagnosis program is stored.

The computer has a data recording means for recording the analysis results of separation membrane 1 and separation membrane 2. Furthermore, the computer diagnoses and outputs the state of the separation membrane using the data recorded in the data recording means and/or the input data. Examples of output data include the presence or absence of a change, the degree of change, the type of chemical change, and the substance causing the change. At this time, the computer outputs a result of a judgment based on predetermined criteria, or an index representing separation membrane performance. As mentioned above, examples of indexes representing separation membrane performance include the removal rate, permeability, solvent permeability coefficient, solute permeability coefficient, solvent permeation amount, and solute permeation amount. Furthermore, the predetermined criteria can be the criteria described above in the judgment method.

The above-mentioned items also serve as examples of whether or not a change occurs, the degree of change, the type of chemical change, and the causative substance.

In the aforementioned program, examples of the analysis results of the separation membrane include at least one of infrared absorption spectroscopy results and elemental composition analysis results. In this case, the aforementioned values can be used as the infrared absorption spectroscopy results or elemental composition analysis results, or the difference between the infrared absorption spectroscopy results or elemental composition analysis results.

When using calculated values as analysis results, for example, the ratio of the maximum infrared absorption intensity in a first wavenumber range in the infrared absorption spectroscopy results to the maximum infrared absorption intensity in a second wavenumber range that includes the absorption band derived from the material being subjected to change assessment, or when using any of the halogen elements, oxygen elements, and nitrogen elements relative to the carbon element in the elemental composition analysis results, as well as their average values, maximum values, median values, and weighted averages, the calculated values can be input into a computer, or the results of the analysis using each analytical method can be input into a computer, calculations can be performed by the computer, and the calculated values can be used to diagnose and output the condition of the separation membrane.

In addition, change profiles according to the progress of chemical changes include those that correlate the analysis results with at least one of the removal rate, transmittance, solvent permeability coefficient, solute permeability coefficient, solvent permeation amount, and solute permeation amount, and examples of these profiles include the change profiles shown in Figures 2 to 6.

For example, as shown in Figure 9, a separation membrane diagnostic program can be used to determine chemical changes and/or chemical changes in the performance of a target separation membrane based on the difference between the analysis results of an unused membrane and the analysis results of a target separation membrane. Based on the difference between the input analysis results of the target separation membrane and the analysis results of an unused separation membrane, the program determines at least one of the presence or absence of a change, the degree of change, the type of chemical change, and the causative substance, and outputs a status diagnosis result. The first embodiment described above can be cited as an example of a status diagnosis method.

Another example is a separation membrane diagnostic program that determines chemical changes and/or chemical changes in separation membrane performance in a target separation membrane based on the difference between the change profile of analysis results according to the progress of chemical changes and the analysis results of the target separation membrane, as shown in Figure 10. From the difference between the input analysis results of the target separation membrane and the analysis results of an unused separation membrane, the program determines at least one of the presence or absence of change, the degree of change, the type of chemical change, and the causative substance, and outputs a status diagnosis result. An example of a status diagnosis method is the second form described above.

As another example, as shown in Figures 11 to 14, there is a separation membrane condition diagnosis program that uses at least either infrared absorption spectroscopy results or elemental composition analysis results as analysis results, and determines chemical changes and/or chemical changes in separation membrane performance of a target separation membrane based on differences between the analysis results of an unused separation membrane or at least either a change profile related to the analysis results depending on the progress of chemical changes, and the analysis results of the target separation membrane. Examples of condition diagnosis methods include the third, fourth, and fifth forms described above. As shown in Figure 15, there is also a separation membrane condition diagnosis program that performs the above-mentioned determination multiple times using at least either infrared absorption spectroscopy results or elemental composition analysis results as analysis results, and integrates these results to make a final determination. Examples of condition diagnosis methods in this case include the third, fourth, and fifth forms described above.

16, a separation membrane condition diagnosis program is provided that uses a change profile relating to the analysis results according to the progress of chemical changes that show a correlation with at least one of the removal rate, solute permeability coefficient, and solvent permeation rate to calculate a target separation membrane performance _S1 from the difference between the input infrared absorption spectroscopy results of the target separation membrane and the change profile relating to the infrared absorption spectroscopy results, calculates a target separation membrane performance _S2 from the difference between the input elemental composition analysis results of the target separation membrane and the change profile relating to the elemental composition analysis results, and determines at least one of the type of chemical change or the causative substance from the difference between _S1 and _S2 from the elemental composition analysis results. Note that the sixth embodiment described above is an example of the condition diagnosis method.

In this case, the output judgment result may be the result of judging at least one of the presence or absence of change, the degree of change, the type of chemical change, and the causative substance based on predetermined judgment criteria (index values), or the index values themselves. As mentioned above, the index values and judgment criteria in this case may include the difference value of the analysis results themselves, as well as the target separation membrane performance calculated using the change potential.

You can choose which of these programs to use depending on the usage and purpose of the target separation membrane.

Another aspect of the present invention is a separation membrane condition diagnosis device that includes a computer for determining the condition of the separation membrane, a data input means for inputting the analysis results of the separation membrane into the computer, and a condition diagnosis means for determining the chemical change of the target separation membrane based on the difference between the analysis results of the target separation membrane and at least one of the analysis results of an unused separation membrane or a change profile according to the progress of chemical change.

The present invention will be explained in more detail below using examples, but the present invention is not limited to these examples in any way.

(Analysis method)
The infrared absorption spectroscopy results of the separation membrane were obtained by total reflection infrared spectroscopy (ATR). Specifically, the results of irradiating a light source onto the separation functional layer side using an FT/IR-4600 (manufactured by JASCO Corporation) and measuring were used. In addition, a single reflection ATR measurement device (ATR PRO ONE) and a diamond cell manufactured by the same company were used as equipment for total reflection measurement. The measurement conditions were a resolution of 4 cm ^-1 and a scan count of 32. The obtained spectrum was expressed in absorbance, and baseline correction was performed using a linear line created from the absorbance at 4000 cm ^-1 and 1800 cm ^-1 . In addition, ATR correction was performed using the instrument's accompanying software (manufactured by JASCO Corporation).

The elemental composition analysis results of the composite separation membrane were obtained by photoelectron spectroscopy (XPS). Specifically, the results were obtained by irradiating a light source onto the separation functional layer side using a Quantera SXM (manufactured by ULVAC-PHI, Inc.). The measurement conditions were: monochromatic Al K _α1,2 ray (1486.6 eV) as the excitation X-ray; X-ray diameter was 200 μm; and photoelectron detection angle was 90°. In addition, 9-point smoothing was performed, and horizontal axis correction was performed with the C1s main peak at 284.6 eV.

The separation membranes to be measured were rinsed with distilled water and vacuum-dried for six hours using an LHV-122 (Espec Corp.) and a TSW-50 (Sato Vacuum Co., Ltd.) to prepare the samples. Separation membranes collected from elements used in the plant were immersed in the specified chemicals (acids and bases), then gently wiped with new (unopened) absorbent cotton thoroughly moistened with distilled water on the separation membrane's functional layer side. The entire membrane was rinsed with distilled water to remove surface contaminants, and then vacuum-dried. Unused separation membranes or membranes that had undergone chemical changes, used to calculate the difference between the separation membrane and analytical results, were pretreated using the same pretreatment method. That is, after immersing in the specified chemicals (acids and bases), the separation membrane's functional layer side was gently wiped with new (unopened) absorbent cotton thoroughly moistened with distilled water, and the entire membrane was rinsed with distilled water to remove surface contaminants, and then vacuum-dried.

(Evaluation method)
The separation membrane performance was evaluated using a flat membrane testing device under the following operating conditions, with the following feed water being passed through.

Feed water (raw water): An aqueous solution (pH = 6.5) prepared by adding and dissolving NaCl in ultrapure water to a concentration of 32,000 mg/L.
Operating conditions: supply water pressure 5.5 MPa, raw water temperature 25°C, concentrated water flow rate 3.5 L/min.

To create the change profile, the solvent permeability coefficient or solute permeability coefficient was calculated using the method described above from the results obtained in the above evaluation.

<Comparative Example 1>
A new TM820V-400 (manufactured by Toray Industries, Inc.) was disassembled, and two circular RO membranes with a diameter of 7.5 cm were collected. One of these RO membranes was immersed in an aqueous solution of ultrapure water to which NaCl had been added so that the concentration was 32,000 mg/L (Sample 1, unused separation membrane). The other RO membrane was immersed for 48 hours in an aqueous solution of ultrapure water to which sodium hypochlorite had been added so that the concentration was 0.5 mg/L (Sample 2). During this process, the solution was continuously supplied to the immersion liquid, and any immersion liquid that overflowed from the container was drained, thereby continuously replacing the immersion liquid and maintaining a constant concentration of the aqueous sodium hypochlorite solution in contact with the RO membrane.

A coloration test based on the Fujiwara method was conducted on each membrane. Specifically, 9 g of 3.0 mol/L aqueous sodium hydroxide solution was weighed into each of two sample bottles, and 1 g of pyridine was added to prepare a chemical solution. A membrane immersed in the NaCl aqueous solution was placed in one sample bottle, and a membrane was placed in the other. The color of the solution in the sample bottle was visually observed after 4 hours, 24 hours, 48 hours, and 96 hours, but the presence or absence of staining was unclear, making it difficult to diagnose the condition of the separation membrane.

Example 1
A new TM820V-400 (manufactured by Toray Industries, Inc.) was disassembled, and two circular separation membranes with a diameter of 7.5 cm were collected. One of these was immersed in an aqueous solution of ultrapure water to which NaCl had been added at a concentration of 32,000 mg/L (Sample 3, unused separation membrane). The other was immersed for 48 hours in an aqueous solution of ultrapure water to which sodium hypochlorite had been added at a concentration of 0.5 mg/L, and then immersed for 1 minute in a 1% aqueous solution of sodium bisulfite (Sample 4). During this process, the solution was continuously supplied to the immersion liquid, and any immersion liquid that overflowed from the container was drained, thereby continuously replacing the immersion liquid and maintaining a constant concentration of the aqueous sodium hypochlorite solution in contact with the RO membrane.

Measure and analyze two points for each film by infrared absorption spectroscopy.In this result, calculate the average value of _RA ÷ _RD , _RB ÷ _RD , _RC ÷ _RD , _RE ÷ _RD at two points for each film, and calculate the ratio of the value to the value of sample 3 that is immersed in NaCl aqueous solution, and the results are 0.92, 0.82, 0.72, 1.00.In other words, for _RA ÷ _RD , _RB ÷ _RD , _RC ÷ _RD , the sample 4 that is immersed in sodium hypochlorite aqueous solution is smaller than the sample 3 that is immersed in NaCl aqueous solution.From this result, it is judged that "there is a change". Note that R _E ÷ R _D was equivalent to that of sample 3 immersed in an NaCl aqueous solution, but as shown in Table 2, three other indices (R _A ÷ R _D , R _B ÷ R _D , R _C ÷ R _D ) with higher accuracy than this index were used to judge that there was a change, so those results were adopted.

Example 2
A new TM820V-400 (manufactured by Toray Industries, Inc.) was disassembled, and two circular separation membranes with a diameter of 7.5 cm were collected. One of these was immersed in an aqueous solution of ultrapure water to which NaCl had been added so that the concentration was 32,000 mg/L (Sample 5, unused separation membrane). The other was immersed for 48 hours in an aqueous solution of ultrapure water to which sodium hypochlorite had been added so that the concentration was 0.5 mg/L, and then immersed for 1 minute in a 1% aqueous solution of sodium hydrogen sulfite (Sample 6). During this process, the solution was continuously supplied to the immersion liquid, and any immersion liquid that overflowed from the container was drained, thereby continuously replacing the immersion liquid and maintaining a constant concentration of the aqueous sodium hypochlorite solution in contact with the RO membrane.

When each film was analyzed using photoelectron spectroscopy (XPS), the ratio of halogen elements to carbon elements was found to be 0.043 in Sample 6. Meanwhile, Sample 5, which was immersed in an aqueous NaCl solution, was below the detection limit and deemed to be 0.000. In other words, the ratio of halogen elements to carbon elements in Sample 6 was greater than that in Sample 5, which was immersed in an aqueous NaCl solution, with the difference being greater than 0, and therefore the result indicated a "change."

Example 3
A new TM820V-400 (manufactured by Toray Industries, Inc.) was disassembled, and five circular separation membranes with a diameter of 7.5 cm were collected. One of the membranes was immersed in an aqueous solution of ultrapure water to which NaCl had been added so that the concentration was 32,000 mg/L (Sample 7, unused separation membrane). The remaining separation membranes were immersed in an aqueous solution of ultrapure water to which sodium hypochlorite had been added so that the concentration was 0.5 mg/L (Samples 8 to 11). The solution was continuously supplied to the immersion liquid, and any immersion liquid that overflowed from the container was drained, allowing the immersion liquid to be continuously replaced. After a predetermined time had elapsed, the separation membranes were sequentially removed from the immersion liquid and immersed in a 1% aqueous solution of sodium hydrogen sulfite for 1 minute.

Infrared absorption spectroscopy was performed at two locations for each membrane, and the average values for each separation membrane were calculated as shown in Table 4. The rate of change was calculated from the ratio to the results for the membrane immersed in NaCl aqueous solution, and the infrared absorption spectroscopy results were obtained.

The differences (differences) in peak wavenumbers at 1680 to 1650 ^cm relative to Sample 7 were determined to be in the order of Samples 11, 10, 9, and 8, and the degree of change was determined to be in the order of Samples 11, 10, 9, and 8. In other words, Sample 8 was determined to be "mild," Sample 9 was determined to be "moderate," and Samples 10 and 11 were determined to be "severe."

Furthermore, the differences (rates of change) in R _A ÷ R _D , R _B ÷ R _D , and R _C ÷ R _D for sample 7 were determined to be greatest in the order of samples 11, 10, 9, and 8, with the separation membranes 11, 10, 9, and 8 showing the greatest change. Furthermore, the differences (rates of change) in R _E ÷ R _D for separation membrane 7 were determined to be greatest in the order of separation membranes 10, 9, and 8 relative to the membranes immersed in an NaCl aqueous solution, with the separation membranes 10, 9, and 8 showing the greatest change. These results are similar to those obtained when the difference in peak wavenumbers between 1680 and 1650 cm ⁻¹ was used as an index, confirming the reliability of the results. On the other hand, the difference (rate of change) of R _E ÷ R _D for Sample 7 was smaller for Sample 11 than for Samples 9 and 10. However, as shown in Tables 2 and 4, Sample 11 was judged to have undergone more progress in change than Sample 10 using the other four more reliable indices. Therefore, the results using the four more reliable indices were used.

Based on the above results, the degree of change was determined to be "mild" for sample 8, "moderate" for sample 9, and "severe" for samples 10 and 11, with sample 11 being more severely affected than sample 10.

Example 4
As in Example 3, unused separation membranes immersed in an aqueous NaCl solution and separation membranes immersed in sodium hypochlorite were prepared, and separation membrane performance evaluation was performed. After that, infrared absorption spectroscopy was performed, and the solvent permeability coefficient and the change profile of the infrared absorption spectroscopy results were obtained as shown in FIG. 17. Specifically, infrared absorption spectroscopy was performed at eight locations for each membrane, the average value was calculated, and the difference (change rate) relative to an unused separation membrane immersed in an aqueous NaCl solution was calculated. In addition, from the performance evaluation results of each separation membrane, the difference (ratio) in solvent permeability coefficient relative to an unused separation membrane immersed in an aqueous NaCl solution was calculated. From the correlation between the difference (change rate) in the above-mentioned analysis results and the difference (ratio) in solvent permeability coefficient, a change profile was obtained as a regression equation by the least squares method. From the results, the criteria for determining chemical change were determined as shown in FIG. 17.

10 cm square membrane pieces were collected from TM820V-400 (manufactured by Toray Industries, Inc.) used in different water treatment plants A to C. Infrared absorption spectroscopy was performed on these pieces, and the results were as shown in Table 5. These results were compared with the change profiles described above, and the degree of change for each membrane was determined as shown in Table 5.

Example 5
A new TML10D (manufactured by Toray Industries, Inc.) was disassembled, and one 10 cm square separation membrane was sampled. Infrared absorption spectroscopy was performed at eight points within the membrane piece, and the average value of R _A ÷ R _D was calculated to obtain the infrared absorption spectroscopy results. This result was used as the result for an unused separation membrane.

A 10 cm square membrane piece was collected from a TML10D (manufactured by Toray Industries, Inc.) used in water treatment plant D. Infrared absorption spectroscopy was performed at eight locations within the membrane piece, and the average value of R _B ÷ R _D was calculated to obtain the infrared absorption spectroscopy results. From each of the above results (average values), a ratio relative to the result for an unused separation membrane was calculated. The degree of change was determined using predetermined numerical standards, and was found to be slight, as shown in Table 6. However, while a ratio of 1.0 is determined to be no change according to the predetermined numerical standards, the result this time differed from the standard by only 0.01, and there were concerns about the accuracy of the determination results due to the small difference from the standard.

Therefore, the first judgment result described above was used as an estimation result, and a second judgment was made using other infrared absorption spectroscopy results. As specific indicators, _RA ÷ _RD and _RC ÷ _RD , which have the same score for the degree of change (mild) as RB ÷ RD _, as shown in Table 2, were used. That is, as when _RB ÷ _RD was used, the average value of _RA ÷ _RD and the average value of _RC ÷ _RD , and each change rate relative to an unused separation membrane were calculated from each infrared absorption spectroscopy result. Furthermore _, as a result of judging the degree of change using predetermined numerical standards, all were judged to be mild. Note that when _RA ÷ _RD or _RC ÷ _RD was used, a ratio of 1.0 was judged to be no change according to the predetermined numerical standards, but the difference from the standard was larger than when _RB ÷ _RD was used. From these, it was determined that the previous estimation results could be confirmed, and the degree of change was judged to be mild.

Example 6
A new TM820M-400 (manufactured by Toray Industries, Inc.) was disassembled, and one circular separation membrane with a diameter of 7.5 cm was sampled. Infrared absorption spectroscopy was performed at eight points within the membrane piece, and the average values of R _A ÷ R _D, R _B ÷ R _{D, and} R _C ÷ R _D were calculated to obtain the infrared absorption spectroscopy results. These results were used as the results for an unused separation membrane.

A 10 cm square membrane piece was collected from TM820M-400 (manufactured by Toray Industries, Inc.) used in water treatment plant E. Infrared absorption spectroscopy was performed at eight locations within the membrane piece, and the average values of R _A ÷ R _D, R _B ÷ R _{D, and} R _C ÷ R _D were calculated to obtain the infrared absorption spectroscopy results. The ratio to the infrared absorption spectroscopy results of the unused membrane described above was calculated, and the degree of change was determined according to predetermined numerical standards. As a result, all were determined to be mild, as shown in Table 7.

Furthermore, to closely examine whether or not there was any change, the results of the aforementioned infrared absorption spectroscopy were used as estimates, and the indicator with the highest score for the presence or absence of change (minor) in Table 2 was used to determine the presence or absence of change. Specifically, elemental composition analysis was performed using photoelectron spectroscopy to use the ratio of halogen elements to carbon elements. As a result, the ratio was below the detection limit for membranes sampled from new TM820M-400 (manufactured by Toray Industries, Inc.), and was deemed to be 0.000. On the other hand, the ratio for membranes sampled from TM820M-400 (manufactured by Toray Industries, Inc.) used at Plant E was 0.017. In other words, the ratio of halogen elements to carbon elements for membranes used at Plant E was higher than that for unused separation membranes, and was deemed to have "changed." Furthermore, when the ratio of halogen elements to carbon elements was used based on predetermined numerical criteria, the degree of change was determined to be minor, which was confirmed to be similar to the infrared absorption spectroscopy results. In other words, it was confirmed that the same results were obtained even with indicators with higher accuracy for minor changes, and as described in the fifth form, it was confirmed that the results were highly reliable.

Example 7
For the results of the unused separation membrane immersed in the NaCl aqueous solution and the separation membrane immersed in the sodium hypochlorite aqueous solution in Example 4, the difference (ratio) in the solute permeability coefficient relative to the unused separation membrane immersed in the NaCl aqueous solution was calculated from the performance evaluation results of each separation membrane, and the infrared absorption spectroscopy results and the change profile for the solute permeability coefficient were obtained as shown in Figure 18 in the same manner as in Example 4. In addition, the elemental composition analysis results were obtained by photoelectron spectroscopy for the separation membrane immersed in the sodium hypochlorite aqueous solution and the separation membrane immersed in the NaCl aqueous solution in Example 4. From the obtained results, the elemental composition analysis results and the change profile for the solute permeability coefficient were obtained as shown in Figure 19. Specifically, photoelectron spectroscopy was performed at one location for each membrane, and the difference with respect to the membrane immersed in the NaCl aqueous solution was calculated, and a change profile was obtained as a regression equation by the least squares method from the correlation between the difference and the solvent permeability coefficient.

TM820V-400 (manufactured by Toray Industries, Inc.) used in water treatment plant F was disassembled, and a 10 cm square membrane piece was collected. Infrared absorption spectroscopy was performed at eight points within the membrane piece, and the average value of R _A ÷ R _D was calculated to obtain the infrared absorption spectroscopy results. Furthermore, the rate of change relative to the membrane immersed in an NaCl aqueous solution was calculated, and the results are shown in Table 8. The results were compared with the above-mentioned change profile to determine the degree of change, and it was determined to be moderate, as shown in Table 8.

To further identify the causative substance, the elemental composition of the aforementioned 10 cm corneal specimen was analyzed using photoelectron spectroscopy. The difference was then calculated for a film immersed in a NaCl aqueous solution.

The ratio _S1 of solute permeability coefficients was estimated from the difference between the results of the previously performed infrared absorption spectroscopy and the change profile related to the infrared absorption spectroscopy results. Furthermore, the ratio _S2 of solute permeability coefficients was estimated from the difference between the results of the elemental composition analysis and the change profile related to the elemental composition analysis results. As a result, as shown in Table 8, since _S1 ÷ _S2 > 3, it was determined that the substance causing the chemical change was something other than a halogen-based agent.

Furthermore, as a result of comparing the results of the photoelectron spectroscopy analysis carried out later with the above-mentioned change profile, the degree of change was judged to be mild as shown in Table 8, but the degree of chemical change and the causative substance were unknown this time. Therefore, as described in the fifth embodiment, the judgment result was adopted based on the rate of change of R _A ÷ R _D (the ratio of 1 - R _A ÷ R _D ), which gave the highest overall evaluation in Table 2. In other words, the degree of change was judged to be moderate.

Example 8
A new TM820M-400 (manufactured by Toray Industries, Inc.) was disassembled, and one circular separation membrane with a diameter of 7.5 cm was collected. Furthermore, a 7.5 cm square membrane piece was collected from the TM820M-400 (manufactured by Toray Industries, Inc.) used in water treatment plant G. The performance of these membrane pieces was evaluated using an aqueous NaCl solution. Furthermore, infrared absorption spectroscopy was performed at eight locations within each membrane piece. Since the extent of change and the causative substance were unknown this time, the extent of change was estimated using _RA ÷ _RD . The average value of _RA ÷ _RD obtained from the infrared absorption spectroscopy results at each of the eight locations was calculated and used as the infrared absorption spectroscopy result. Using the same procedure, the ratio to the analysis result of a separation membrane disassembled from a new TM820M-400 (manufactured by Toray Industries, Inc.) was obtained. This was used as the analysis result of an unused separation membrane, and the ratio to this was calculated, resulting in the results shown in Table 9.

The degree of change was estimated using predetermined numerical criteria and was judged to be moderate, as shown in Table 9.

Since the degree of change was determined to be moderate, further estimation of performance changes due to the change and identification of the causative substance were carried out.

Furthermore, the first judgment result was taken as an estimated result, and a second judgment was carried out using R _B ÷R _D , which has the same score as R _A ÷R _D shown in Table 2, to confirm the result.

From the infrared absorption spectroscopy results obtained above, the ratio of R _B ÷ R _D to the analysis result of an unused separation membrane was also obtained using the procedure described above. Furthermore, the degree of change was determined based on predetermined numerical criteria and was found to be moderate, as shown in Table 9. In other words, the degree of change was also determined to be moderate when R _B ÷ R _D was used. Since this was the same as the previous estimated result, the final determination result was also determined to be moderate.

Next, the performance changes were estimated and the causative substances were identified. As in Example 4, a new TM820M-400 (manufactured by Toray Industries, Inc.) was disassembled to obtain unused separation membranes immersed in NaCl aqueous solution and separation membranes immersed in sodium hypochlorite. From the performance evaluation results of each separation membrane, the difference (ratio) in solute permeability coefficient relative to unused separation membranes immersed in NaCl aqueous solution was calculated. Furthermore, infrared absorption spectroscopy results were performed at eight locations within each membrane piece, and a change profile for the infrared absorption spectroscopy results and solute permeability coefficient was obtained as in Example 4. Furthermore, elemental composition analysis was performed on each separation membrane using photoelectron spectroscopy, and a change profile was created from the obtained results.

In addition, elemental composition analysis using photoelectron spectroscopy was performed on membrane pieces collected from the previously evaluated new membrane and the TM820M-400 (manufactured by Toray Industries, Inc.) used in water treatment plant G. The results were 0.001 for the new membrane and 0.050 for the separation membrane used in plant G. In other words, the difference between these was 0.049, as shown in Table 9. When the elemental composition analysis results were used based on predetermined numerical standards, the degree of change was determined to be moderate, as shown in Table 10. This result was consistent with the determination results from infrared absorption spectroscopy. In other words, as described in the fifth form, it was confirmed that the previous determination results were highly reliable.

As shown in Table 10, for the rate of change in the infrared absorption spectroscopy results (ratio of 1- _RA ÷ _RD ), the solute permeability coefficient ratio _S3 was estimated from the difference between the above-mentioned infrared absorption spectroscopy results and the change profile related to the infrared absorption spectroscopy results. Furthermore, the solute permeability coefficient ratio _S4 was estimated from the difference between the above-mentioned elemental composition analysis results and the change profile related to the elemental composition analysis results. As a result, since _S3 ÷ _S4 ≦ 3, it was determined that the substance causing the chemical change was a halogen-based agent.

For each of the above examples, the analytical results, diagnostic methods, and corresponding invention forms used are shown in Table 11. The diagnostic results shown in Table 3 based on the corresponding invention form are also listed. Each symbol is the same as in Table 3.

The present invention makes it possible to easily and quickly determine chemical changes and/or chemical changes in separation membrane performance, regardless of the degree of change, including chemical changes that were difficult to diagnose using conventional methods, making it possible to diagnose the condition of separation membranes regardless of the degree of change. Furthermore, it is possible to determine the type of chemical change and the causative substance, which was difficult using conventional technology. Use of the present invention makes it easier to identify the cause of chemical changes in separation membranes and select countermeasures to be taken, and is expected to lead to a definite improvement in the operating conditions of water treatment plants.

1: Raw water storage tank 2: Raw water supply pump 3: Pretreatment membrane filtration unit 4: Pretreatment membrane filtered water storage tank 5: Separation membrane filtration unit 6: Booster pump 7: Booster pump 8: Raw water piping 9: Pretreatment membrane filtered water piping 10: Separation membrane filtered feed water piping 11: Separation membrane filtered permeate water piping 12: Separation membrane filtered concentrated water piping 13: Hose 14: Flow meter 15: One-touch joint 16: Water passage container opening/closing part 17: Flow rate adjustment valve 18: Flow direction 19: Water passage container 19a: Unit water passage container 20: Separation membrane

Claims (13)

A separation membrane condition diagnosis method for determining chemical changes and/or chemical changes in separation membrane performance of separation membrane 2 relative to separation membrane 1 based on a difference between an analysis result of separation membrane 1 and an analysis result of separation membrane 2, comprising:
The analysis results include the following infrared absorption spectroscopy results and elemental composition analysis results (1 ) :
The separation membrane contains polyamide and polysulfone,
The degree of chemical change and _{/ or} chemical change in separation membrane performance of separation membrane 2 relative to separation membrane 1 is estimated from the difference between the infrared absorption spectroscopy result (1) RA ÷ RD of separation membrane 1 and the infrared absorption spectroscopy result (1) RA ÷ _RD of _{separation membrane} 2 _, and the change profile relating to the correlation between the infrared absorption spectroscopy result (1) RA ÷ RD and separation membrane performance;
the degree of chemical change and/or chemical change in separation membrane performance of separation membrane 2 relative to separation membrane 1 is estimated from the difference between the elemental composition analysis results of separation membrane 1 and separation membrane 2 and a change profile relating to the correlation between the elemental composition analysis results and separation membrane performance;
A separation membrane condition diagnosis method characterized by _determining at least one of the degree of change , the type of chemical change, and the causative substance based on the estimated result of separation membrane performance change based on the infrared absorption spectroscopy result (1) RA _÷ RD and the estimated result of separation membrane performance change based on the elemental composition analysis result.
(1) R _A ÷ R _D
( where R _A is the maximum infrared absorption intensity in the range of 1680 to 1650 cm ⁻¹ , and R _D is the maximum infrared absorption intensity in the range of 1260 to 1230 cm ⁻¹ .) 2. The separation membrane condition diagnosis method according to claim 1, wherein the analysis result of the separation membrane 1 is the analysis result of an unused separation membrane, and the change profile relating to the analysis result is a correlation between the analysis result and at least one of the following indicators of separation membrane performance: removal rate, permeability, solvent permeability coefficient, solute permeability coefficient, solvent permeation amount, and solute permeation amount. 2. The separation membrane condition diagnosis method according to claim 1, wherein the elemental composition analysis result is at least one of the following:
(1) The ratio of halogen elements to carbon elements. (2) The ratio of oxygen elements to carbon elements. (3) The ratio of nitrogen elements to carbon elements. the change profile relating to the analysis results is a correlation with at least one of a removal rate, a solute permeability coefficient, and a solvent permeation amount among separation membrane performances;
The separation membrane condition diagnosis method according to claim 1, characterized in that at least one of the type of chemical change or the causative substance is determined from the difference between the estimated result of the separation membrane performance change based on the infrared absorption spectroscopy result (1) RA ÷ RD and the estimated result of the separation membrane performance change based on the elemental _composition analysis _result . 4. The separation membrane condition diagnosis method according to claim 1, wherein the result of the elemental composition analysis is (1) the ratio of halogen elements to carbon elements as set forth in claim 3 . A separation membrane condition diagnosis method as described in claim 4, characterized in that when the degree of change is determined to be mild or moderate using the method described in claim 1, if the ratio _Sr1 of the solute permeability coefficients of the target separation membrane performance calculated using (1) _RA ÷ _RD as described in claim 1 is three times or less ( _Sr1 ÷ Sr2 ≦ 3) the ratio _Sr2 of the solute permeability coefficients of the target separation membrane performance estimated using ( ₁ ) the ratio of halogen elements to carbon elements as described in claim 3, the causative substance is determined to be a halogen-based agent, and if it is more than three times ( _Sr1 ÷ _Sr2 > 3), the causative substance is determined to be other than a halogen-based agent. The separation membrane condition diagnosis method according to claim 1, characterized in that the elemental composition analysis results are obtained by irradiating the separation membrane with X-rays or electron beams from the functional layer side. The separation membrane condition diagnosis method according to claim 1, wherein the separation membrane is one of the following:
A: Separation membrane collected from a semipermeable membrane element that separates feed water into permeate and concentrate at a water treatment plant. B: Separation membrane installed inside a water-permeable member installed in a water supply line at a water treatment plant. C: A semipermeable membrane element that separates feed water into permeate and concentrate at a water treatment plant is used, and the separation membrane is installed inside a water-permeable member installed in a concentrate line. In order to determine the state of the separation membrane, the computer is made to function as a data input means for inputting the analysis results of the separation membrane into the computer, a data recording means for recording the input data in the computer, and a means for determining a chemical change in the separation membrane and/or a chemical change in the performance of the separation membrane based on the input and/or recorded data, and based on the difference between the analysis results of separation membrane 1 and separation membrane 2,
The analysis results include the following infrared absorption spectroscopy results and elemental composition analysis results (1 ) :
The separation membrane contains polyamide and polysulfone,
The degree of chemical change and _{/ or} chemical change in separation membrane performance of separation membrane 2 relative to separation membrane 1 is estimated from the difference between the infrared absorption spectroscopy result (1) RA ÷ RD of separation membrane 1 and the infrared absorption spectroscopy result (1) RA ÷ _RD of _{separation membrane} 2 _, and the change profile relating to the correlation between the infrared absorption spectroscopy result (1) RA ÷ RD and separation membrane performance;
the degree of chemical change and/or chemical change in separation membrane performance of separation membrane 2 relative to separation membrane 1 is estimated from the difference between the elemental composition analysis results of separation membrane 1 and separation membrane 2 and a change profile relating to the correlation between the elemental composition analysis results and separation membrane performance;
At least one of the degree of change , the type of chemical change, and the causative substance is determined based on the result of estimating the change in separation membrane performance based on the infrared absorption spectroscopy result (1) R _A ÷ R _D and the result of estimating the change in separation membrane performance based on the result of elemental composition analysis,
A separation membrane condition diagnosis program that functions as condition diagnosis means for determining chemical changes and/or chemical changes in separation membrane performance of separation membrane 2 relative to separation membrane 1 .
(1) R _A ÷ R _D
( where R _A is the maximum infrared absorption intensity in the range of 1680 to 1650 cm ⁻¹ , and R _D is the maximum infrared absorption intensity in the range of 1260 to 1230 cm ⁻¹ .) The separation membrane condition diagnosis program of claim 9, characterized in that the change profile related to the analysis results is a correlation between the analysis results and at least one of the following indicators representing separation membrane performance: removal rate, permeability, solvent permeability coefficient, solute permeability coefficient, solvent permeation amount, and solute permeation amount. The separation membrane condition diagnosis program of claim 9, characterized in that when the degree of change is determined to be mild or moderate, if the ratio _Sr1 of the solute permeability coefficients of the target separation membrane performance calculated using (1) _RA ÷ _RD is three times or less ( _Sr1 ÷ _Sr2 ≦ 3) the ratio _Sr2 of the solute permeability coefficients of the target separation membrane performance estimated using (1) the ratio of halogen elements to carbon elements in the elemental composition analysis results, the causative substance is determined to be a halogen-based agent, and if it is more than three times ( _Sr1 ÷ _Sr2 > 3), the causative substance is determined to be other than a halogen-based agent. A separation membrane condition diagnosis device equipped with the separation membrane condition diagnosis program according to claim 9 . A computer-readable recording medium device having the separation membrane condition diagnosis program according to claim 9 recorded thereon.