JP7148124B2 - Inspection method for anion exchange membrane containing polyvinyl chloride component - Google Patents

Description

Article 30, Paragraph 2 of the Patent Law applies Name of research meeting: International Conference on Membrane Processes (Proceedings) Organizer name: CZECH MEMBRANE PLATFORM Publication date: May 13, 2018 Name of research meeting: International Conference on Membrane Processes (oral presentation) Organizer Name: CZECH MEMBRANE PLATFORM Date of announcement: May 15, 2018

TECHNICAL FIELD The present invention relates to a method for inspecting deterioration in performance associated with deterioration due to use of an anion exchange membrane containing a polyvinyl chloride component.

An ion-exchange membrane is made by holding an ion-exchange resin on a substrate sheet having a certain amount of voids, and has the function of allowing specific ions to pass through using electrical energy. Such ion exchange membranes include anion exchange membranes and cation exchange membranes.

That is, the anion exchange membrane uses an anion exchange resin having an anion exchange group as a functional group of the ion exchange resin, and by applying electrical energy, anions such as chloride ions (Cl ⁻ ) can be permeated. do. On the other hand, the cation exchange membrane uses a cation exchange resin having a cation exchange group as a functional group, and permeates cations such as sodium ions (Na ⁺ ) by applying electrical energy.

Such ion-exchange membranes are typically used in electrodialysis, for example, anion-exchange membranes and cation-exchange membranes are alternately arranged between electrodes, and a constant voltage is applied while flowing an aqueous solution containing ions. As a result, ions can be concentrated, desalted, purified, recovered, etc., and are used in various applications such as salt production from seawater, production of drinking water from brackish water, and desalination of soy sauce.

By the way, when the ion exchange membrane as described above is installed in an actual apparatus and operated, various problems arise.
For example, when concentrating and desalting seawater by electrodialysis, it is necessary to keep the salt concentration in the desalting chamber above a certain level. can run out and instead water splits into hydrogen and hydroxide ions. These hydroxide ions react with polyvalent ions such as calcium in the concentrating compartment to form hydroxide scales, which not only cause problems such as blockage of the flow path, making the operation impossible, but also directly It may detach the anion-exchange groups of the exchange membrane or destroy the skeleton and network structure of the membrane, resulting in deterioration of the performance and strength of the ion-exchange membrane itself. In addition, especially in the food industry, a phenomenon called fouling (membrane contamination), in which organic substances are adsorbed to the anion exchange membrane and deteriorate its performance, can occur. In addition, an alkaline solution may be used, and this alkali may destroy the skeleton and network structure of the membrane, resulting in reduced performance and strength. In particular, when polyvinyl chloride is used as a base material fabric or base sheet, or when polyvinyl chloride is used as a thickening agent, the alkali dehydrochlorinates the polyvinyl chloride to form a structure called polyene, which results in a membrane. may be colored (see, for example, Non-Patent Document 1).

Journal of Membrane Science, 446 (2013) 255-265

Therefore, in an actual device using an ion-exchange membrane, the performance of the membrane (e.g., electrochemical properties, mechanical strength) is measured at regular intervals in order to understand the deterioration of membrane performance during actual operation. (monitoring) is necessary. However, for such monitoring, an ion exchange membrane incorporated in an actual device must be cut out for evaluation and attached to a measuring device for evaluating its characteristics. That is, there is a problem that the film must be destroyed for inspection, and the film used for inspection and measurement cannot be used in an actual machine. In addition, as an electrochemical property, for example, in order to measure the anion blocking rate, it is necessary to fix the sample in the anion-containing aqueous solution in a liquid-tight state for a long time, and it is extremely complicated to evaluate it on site. is.

As a result of many experiments and studies on such problems, the inventors of the present invention have found that, particularly in an anion exchange membrane containing a polyvinyl chloride component, the degree of physical properties and electrochemical properties of the membrane deteriorated by alkali contact is The inventors have found that there is a correlation between the optical properties for visible light and the chlorine intensity measured by fluorescent X-ray analysis.

Accordingly, it is an object of the present invention to provide an inspection method for an anion exchange membrane containing a polyvinyl chloride component, which is not necessarily a destructive inspection, but can be easily inspected for performance deterioration of the membrane due to actual use. .

According to the present invention, an unused polyvinyl chloride component-containing anion exchange membrane is prepared,
The anion-exchange membrane is brought into contact with an alkaline aqueous solution to perform a deterioration accelerated test. Alternatively, by measuring the electrochemical properties, a calibration curve showing changes in physical properties and/or electrochemical properties of the anion exchange membrane with respect to changes in optical properties or fluorescent X-ray intensity is prepared,
The optical properties or fluorescent X-ray intensity of the polyvinyl chloride component-containing anion exchange membrane in use is measured with respect to visible light, and the anion exchange in use is determined from the optical properties or the fluorescent X-ray intensity measured value based on the calibration curve. A method for testing an anion exchange membrane containing a polyvinyl chloride component is provided, characterized in that the physical and/or electrochemical properties of the membrane are determined.

In the inspection method of the present invention,
(1) Measuring absorbance as an optical characteristic of the anion exchange membrane with respect to visible light, which is measured for each degree of deterioration; (2) Determining mechanical strength or water content as a physical characteristic of the anion exchange membrane. ,
(3) measuring Young's modulus as the mechanical strength for determining the physical properties of the anion exchange membrane; (4) determining the electrical resistance or transference number as the electrochemical properties of the anion exchange membrane;
This aspect can be preferably adopted.

In the inspection method of the present invention, as described above, the physical properties (for example, mechanical strength and water content) and electrical properties (for example, electrical resistance and transport number) of an anion exchange membrane containing a vinyl chloride component are measured against visible light. It is based on the new knowledge that there is a correlation with the chlorine intensity measured by optical properties and fluorescent X-ray analysis. For a vinyl-containing anion exchange membrane (hereinafter sometimes simply referred to as a Cl-containing anion exchange membrane), the optical properties with respect to visible light or the chlorine strength by fluorescent X-ray analysis are measured, and at the same time, the physical properties (for example, mechanical strength, Moisture content) or electrochemical properties (for example, electrical resistance and transference number) are measured, and the relationship with optical properties or chlorine strength is plotted to create a calibration curve, and based on this calibration curve, used in an actual machine It is to determine the degree of deterioration of the Cl-containing anion exchange membrane that has been used.

Furthermore, optical properties for visible light and X-ray fluorescence analysis can be measured without necessarily cutting and destroying the film. For this reason, in the present invention, the Cl-containing anion exchange membrane used in the actual equipment is measured by measuring the absorbance with respect to visible light or measuring the chlorine intensity by fluorescent X-ray analysis. It has the great advantage of being able to inspect performance degradation without destroying it. In other words, when performance deterioration of a certain level or more is determined by the calibration curve from the measured absorbance and chlorine intensity, the Cl-containing anion exchange membrane is subjected to replacement or washing, etc., and the performance deterioration reaches a certain level. If it is determined that it has not reached the limit, the use of the actual machine is continued as it is.
Thus, the inspection method of the present invention can inspect without necessarily destroying the Cl-containing anion exchange membrane used in the actual machine.

FIG. 4 is a graph showing the relationship between absorbance and electrical resistance retention with respect to visible light (600 nm) for Cl-containing anion exchange membranes subjected to a deterioration accelerated test at 40° C. FIG. FIG. 4 is a graph showing the relationship between the absorbance for visible light (600 nm) and the retention of Young's modulus for a Cl-containing anion exchange membrane subjected to a deterioration accelerated test at 40° C. FIG. FIG. 2 is a diagram showing the relationship between absorbance and transference number (proton transmission blocking rate) retention for visible light (600 nm) for Cl-containing anion exchange membranes subjected to a deterioration accelerated test at 40° C. FIG. FIG. 4 is a diagram showing the relationship between the absorbance for visible light (600 nm) and the water content retention rate for Cl-containing anion exchange membranes subjected to a deterioration acceleration test at 40° C. FIG. FIG. 4 is a diagram showing the relationship between the reflectance for visible light (600 nm) and the electrical resistance retention rate for Cl-containing anion exchange membranes subjected to a deterioration acceleration test at 40° C. FIG. FIG. 4 is a diagram showing the relationship between the reflectance for visible light (600 nm) and the electrical resistance retention rate for Cl-containing anion exchange membranes subjected to a deterioration acceleration test at 60° C. FIG. FIG. 4 is a diagram showing the relationship between the reflectance for visible light (600 nm) and the retention of Young's modulus for Cl-containing anion exchange membranes subjected to a deterioration acceleration test at 40° C. FIG. FIG. 4 is a diagram showing the relationship between the chlorine strength retention rate and the electrical resistance retention rate measured by fluorescent X-ray analysis for a Cl-containing anion exchange membrane subjected to a deterioration accelerated test at 40°C. FIG. 4 is a graph showing the relationship between chlorine strength retention and Young's modulus retention measured by fluorescent X-ray analysis for Cl-containing anion exchange membranes subjected to a deterioration accelerated test at 40°C.

<Anion exchange membrane containing polyvinyl chloride component>
The anion exchange membrane to be tested in the present invention contains a polyvinyl chloride component.
That is, an anion exchange membrane containing a polyvinyl chloride component (Cl-containing anion exchange membrane) is degraded by contact with an alkali, for example, dehydrochlorination occurs from polyvinyl chloride, and a polyene structure is formed. coloring. In the present invention, the degree of dehydrochlorination is determined by optical properties for visible light or chlorine intensity by fluorescent X-ray analysis. Therefore, the anion exchange resin to be tested in the present invention must contain polyvinyl chloride.

In the present invention, the Cl-containing anion exchange membrane to be tested is not limited in composition or production method as long as it contains polyvinyl chloride.

For example, there is a paste method as a representative method for producing an anion exchange membrane. In the paste method, an ion-exchange resin component (a monofunctional monomer for obtaining a precursor polymer for introducing ion-exchange groups and, if necessary, a It is produced by applying a paste prepared by adding a polyfunctional monomer), a thickener, and, if necessary, various additives, polymerizing the monomer, and then subjecting it to an ion-exchange group-introducing treatment.

Typical examples of the base sheet include porous sheets, woven fabrics, and non-woven fabrics made of polyolefins such as polyvinyl chloride, polyethylene, and polypropylene.
In the ion exchange resin component, styrene, chloromethylstyrene, vinylpyridine, etc. are used as monofunctional monomers into which ion exchange groups are introduced, and divinylbenzene, divinylbiphenyl, etc. are used as polyfunctional monomers. In any case, as a functional group, it has an anion exchange group such as a primary to tertiary amino group, a quaternary ammonium salt, a pyridyl group, an imidazole group, a quaternary pyridinium group, or such an anion exchange group is introduced. Anything that can be done is acceptable.
Furthermore, polyvinyl chloride powder, rubber, and other various polymer powders are used as the thickening agent.

That is, the Cl-containing anion exchange membrane to be inspected in the present invention may use polyvinyl chloride as a base sheet for reinforcement, a thickening agent, or the like. In order to determine the physical properties and/or electrochemical properties of an anion exchange membrane with high reliability, the content of polyvinyl chloride should be 20 to 80% by mass, particularly It is preferably 50 to 70% by mass.

<Deterioration accelerated test>
In the present invention, the Cl-containing anion exchange membrane to be inspected is subjected to accelerated deterioration test.
This accelerated deterioration test is conducted in order to cause dehydrochlorination from polyvinyl chloride as described above. The membrane used) is brought into contact by immersion or the like.

By the way, the relationship between the physical properties and electrical properties of the anion-exchange membrane subjected to the accelerated deterioration test and the optical properties and chlorine strength of the membrane is best correlated when the accelerated deterioration test is performed under the same temperature conditions. In the case of resistance and Young's modulus, there is a good proportional relationship. However, as the temperature of the deterioration acceleration test increases, even if the optical properties and chlorine strength are the same, the degree of deterioration of the film progresses slightly, and the electrical resistance and Young's modulus also slide to slightly worse values. . Therefore, in the present invention, when using an anion exchange membrane in an actual machine such as electrodialysis, the liquid temperature is controlled at a constant temperature, and the accelerated deterioration test is performed at substantially the same temperature (within ±5 ° C.). It is most preferable to accurately determine the relationship between the physical properties and electrical properties at the same temperature and the absorbance and chlorine intensity of the film in order to determine the degree of deterioration of the film with high accuracy.

In general, when an anion exchange membrane is used in an actual machine such as electrodialysis, it is usually operated at room temperature, preferably with the liquid temperature in the dialysis tank controlled within a range not exceeding 40°C. On the other hand, if the liquid temperature fluctuation in the dialysis tank is within the range of 20 to 70° C. (more preferably 20 to 50° C.), the progress of deterioration of the membrane accompanying the temperature rise is not so great. don't be harsh. Therefore, in the present invention, even if the accelerated deterioration test is carried out by controlling the above constant temperature, and on the other hand, the use of the anion exchange membrane in the actual equipment is not necessarily carried out by controlling the above constant temperature. If the width of liquid temperature fluctuation is set within the range of 20 to 70° C., the width of decrease in the physical properties and electrical properties of the film can be kept within a certain range. Therefore, even in such a mode, the degree of deterioration of the film can be roughly grasped, which is very significant as a simple deterioration determination method.

Therefore, the test conditions for the accelerated deterioration test described above, such as the type of alkaline aqueous solution used, the alkali concentration, etc., are not particularly limited, but in general, conditions that cause film deterioration in a relatively short period of time are employed. Also, the liquid temperature of the alkaline aqueous solution is preferably selected from the range of 20 to 70° C. as described above. Further, it is more preferable to set the liquid temperature to substantially the same temperature (within ±5° C.) as when an anion exchange membrane such as electrodialysis is used in an actual machine. Incidentally, in the examples described later, accelerated deterioration tests were performed by immersing Cl anion exchange membranes in three stages of NaOH aqueous solutions of 0.01M, 0.1M, and 1M held at temperatures of 40°C and 60°C. ing.

<Preparation of calibration curve>
In the present invention, the accelerated test is used to measure the physical properties and electrochemical properties of the Cl-containing anion exchange membrane with respect to the deterioration level, and prepare a calibration curve.
This deterioration level is identified by chlorine intensity by optical properties for visible light or fluorescent X-ray analysis.

That is, when the Cl-containing anion exchange membrane is exposed to alkali, dehydrochlorination occurs from polyvinyl chloride to form polyene, which first develops a yellow color, and when the contact with alkali continues, it turns purple. As the deterioration progresses in this way, the Cl-containing anion exchange membrane is discolored, and the degree of this discoloration can be identified by the optical properties with respect to visible light.
Optical properties include transmittance, absorbance, and reflectance.
As described above, as the deterioration progresses, the color changes to purple. ), while it becomes saturated, it becomes difficult to distinguish absorbance (transmittance, reflectance) changes on the high wavelength side. Therefore, when identifying the degree of deterioration based on the optical properties for visible light, it is preferable to measure with a wavelength of 700 nm or less, particularly 500 to 700 nm. Incidentally, in the examples, optical characteristics are measured at a wavelength of 600 nm.

Further, in fluorescent X-ray analysis, the degree of deterioration is identified by chlorine intensity. That is, the degree of deterioration is identified by the degree of dehydrochlorination from polyvinyl chloride. For example, as deterioration progresses, the amount of dehydrochlorination increases, so the chlorine intensity measured by fluorescent X-ray analysis decreases. Normally, the intensity of Ka line of chlorine can be read.

Thus, in the present invention, the degree of deterioration is identified by optical property measurement and chlorine intensity, but what is important here is not necessarily cutting out a sample for analysis from the Cl-containing anion exchange membrane (that is, destructive testing) and can be measured. In particular, in the case of fluorescent X-ray analysis, a compact portable (handheld) type is commercially available, and if this is used, direct measurement can be performed without breaking the membrane. Similarly, in the measurement of optical properties for visible light, a compact portable (handheld) reflection method is commercially available. Moreover, even if destruction is unavoidable, optical analysis has the advantage of being easier to perform than electrochemical analysis.

In the present invention, the degree of deterioration is identified by measuring the optical properties or chlorine strength as described above, but at the same time, the physical properties or electrochemical properties are measured, and the identified degree of deterioration is determined. Physical characteristics or electrochemical characteristics are plotted to prepare a calibration curve.

<Inspection of Cl-containing anion exchange membrane used in actual equipment>
By the way, the physical properties and electrochemical properties of a film used in an actual machine are usually measured by a film breakdown test. Changes in physical properties and electrochemical properties can be estimated by measuring chlorine intensity by optical property measurement for visible light or fluorescent X-ray analysis, not necessarily by destructive inspection.

For example, FIG. 1 shows a calibration curve obtained by plotting the absorbance measured at a wavenumber of 600 nm and the electrical resistance retention after performing the accelerated deterioration test described above.
The electric resistance retention rate is calculated by the following formula.
Electric resistance retention (%)
= 100 x (electrical resistance value of deteriorated film)/(electrical resistance value of film before accelerated deterioration)
AC electrical resistance was measured here. As can be understood from FIG. 1, there is a clear correlation between the absorbance and the electrical resistance value. Therefore, by measuring the absorbance, the electrical resistance value of the film can be estimated from the above calibration curve. .

FIG. 2 also shows a calibration curve plotting the absorbance measured at a wavenumber of 600 nm and the retention of Young's modulus.
The Young's modulus retention rate is calculated by the following formula.
Young's modulus retention rate (%)
= 100 x (Young's modulus of deteriorated film)/(Young's modulus of film before accelerated deterioration)
As can be seen from FIG. 2, there is a clear correlation between this absorbance and Young's modulus, so by measuring the absorbance, the Young's modulus of the film can be estimated from the above calibration curve.
Similarly, FIG. 3 indicates that the transport number and FIG. 4 indicate that the water content can be estimated.
5 and 6 show that the electrical resistance can be estimated from the reflectance, and FIG. 7 shows that the Young's modulus can be estimated from the reflectance.

Further, FIG. 8 shows a calibration curve plotting the chlorine strength retention rate and the electrical resistance value measured by fluorescent X-ray analysis.
Incidentally, the chlorine strength retention rate is calculated by the following formula.
Chlorine strength retention rate (%)
= 100 x (chlorine intensity of deteriorated film)/(chlorine intensity of film before deterioration promotion)
As is clear from FIG. 8, the electric resistance decreases as the strength of chlorine decreases, and there is a clear correlation between the two. Therefore, the electrical resistance value of the film can be estimated from the above calibration curve also by measuring the chlorine intensity by fluorescent X-ray analysis.

FIG. 9 shows a calibration curve plotting Young's modulus against chlorine strength retention measured by fluorescent X-ray analysis.
As is clear from FIG. 9, the Young's modulus decreases as the strength of chlorine decreases, and there is a clear correlation between the two. Therefore, the Young's modulus of the film can also be estimated from the calibration curve by measuring the chlorine intensity by fluorescent X-ray analysis.

As described above, in the present invention, the accelerated deterioration test is performed on the Cl-containing anion exchange membrane used in the actual equipment, and the optical characteristics with respect to visible light or the chlorine intensity by fluorescent X-ray analysis is measured, and the electrochemical characteristics such as the electrical resistance value are measured. , Young's modulus, and other physical properties are measured and the calibration curve is measured, the optical properties of the Cl-containing anion exchange membrane installed in the actual machine can be measured without destructive inspection, and the optical properties against visible light or fluorescent X-rays By measuring the strength of chlorine by analysis, it is possible to grasp the degree of deterioration of the attached membrane, and based on this, the continuation of use or replacement of the membrane will be carried out.

In the above example, the electrical resistance value is taken as an example of the electrochemical property, and the Young's modulus is taken as an example of the physical property to show the correlation between the optical property and the chlorine strength. Of course, it is also possible to prepare a calibration curve by measuring parameters other than Young's modulus.
For example, in the case of electrochemical properties, it is known that there is a correlation between the electrical resistance value of the film and the transference number. You can also keep Here, the transference number is not limited to the so-called static transference number, and includes indices representing ion permeability and selectivity such as permeability and rejection of specific ions (eg, protons) during electrodialysis. It is also known that, in terms of physical properties, there is a correlation between water content and electrical resistivity. Therefore, it is also possible to prepare a calibration curve using moisture content in addition to Young's modulus. Similarly, physical properties include ion exchange capacity, diffusion coefficient, mechanical strength (bursting strength [Mullen method], puncture strength, tensile strength obtained by tensile test (maximum point, breaking point), tensile elongation (maximum point, breaking point), etc., it is possible to create a calibration curve using these measured values.

The electrical resistance may also fluctuate due to factors other than the dehydrochlorination of vinyl chloride, though not as much as in the case of dehydrochlorination. That is, in the Cl anion-exchange membrane, contact with an alkali readily causes elimination of ion-exchange groups in addition to dehydrochlorination of vinyl chloride, and elimination of ion-exchange groups increases electrical resistance. In addition, the electrical resistance may increase if a counterion that is difficult to migrate binds to the ion-exchange group or if other factors such as fouling and scaling are combined. On the other hand, in the case of physical properties such as mechanical strength, changes in properties caused by factors other than dehydrochlorination of PVC are small. Therefore, physical properties such as mechanical strength are more reliable and preferable than electrical resistance in terms of the accuracy of characterization of the anion exchange membrane in use.

The invention is illustrated by the following experimental examples.

Cl-containing anion exchange membrane used in the experiment;
Containing polyvinyl chloride woven fabric as a base sheet Polyvinyl chloride content per Cl-containing anion exchange membrane: 63% by mass
(The content of polyvinyl chloride in the anion exchange resin is about 25% by mass)
Initial absorbance (wavelength 600 nm): 0.0
Initial chlorine strength: 15337 cps
Initial AC resistance: 2.36 Ω cm ²
Initial Young's modulus: 1085 N/mm ²

Absorbance and reflectance measurements;
Using a visible light spectrophotometer V-730 manufactured by JASCO Corporation, the absorbance or reflectance at a wave number of 600 nm was measured for the transparent reference sample and the sample film.
The difference between the absorbance or reflectance of the sample film and the reference sample was taken as the absorbance or reflectance of the sample film.

measurement of chlorine strength;
As a fluorescent X-ray analyzer, a handheld fluorescent X-ray device VANTA manufactured by Olympus Co., Ltd. was used to measure the intensity of Ka rays attributed to chlorine.

measurement of the AC resistance of the membrane;
A 0.5 N saline solution maintained at 25° C. was circulated through the resistance measuring acrylic cell.
A sample membrane (Cl-containing anion exchange membrane) was sandwiched in this cell, and an AC measuring device LCR-4263A manufactured by HIOKI was used to measure the total AC resistance (R2) at a frequency of 1000 cycles. Also, the AC resistance (R1) was measured without the film sandwiched therebetween, and the AC resistance (ER) of the film was calculated from the following formula.
ER = R2 - R1

measurement of membrane transference (proton blocking rate);
A handmade acrylic cell was equipped with platinum electrodes and a test piece was sandwiched between them. A 2M-H ₂ SO ₄ solution was filled in the anode cell and a 0.25-H ₂ SO ₄ solution in the cathode cell. Each was stirred with a magnetic stirrer and maintained at 25°C. Electricity was applied at a current density of 10 dA/dm ² for 3600 seconds, and the H ⁺ ion concentration (M2) of the anode cell and the initial H ⁺ ion concentration (M1) before the application of electricity were titrated with 0.1M-NaOH, and the proton permeation was calculated according to the following formula. A rejection rate PR (%) was calculated.
PR = (M2/M1) x 100

measurement of membrane moisture content;
After washing the test piece equilibrated with 0.5M-NaCl solution with deionized water, it was sandwiched between two pieces of filter paper and lightly pressed to wipe off moisture on the surface. The weight (Wa) of the wet test piece was measured immediately.
Subsequently, it was placed in a vacuum dryer DP-32 (manufactured by Yamato Scientific) maintained at 60° C. and vacuum-dried for 4 hours. The weight (Wb) of the dry test piece was measured, and the moisture content Wc (%) of the film was calculated from the following formula.
Wc=[(Wa−Wb)/Wb]×100

measurement of Young's modulus;
A mechanical strength test was performed using a tensile tester "Tensilon" manufactured by A&D Co., Ltd., and the Young's modulus was calculated from the resulting stress-strain curve.

<Example 1>
The sample Cl-containing anion exchange membrane was immersed in 0.01 M, 0.1 M, and 1 M NaOH aqueous solutions maintained at 40°C, and accelerated deterioration test was performed at 40°C.
These films were taken out at predetermined time intervals from 1 hour to 1 week, the absorbance to visible light (wavelength 600 nm) was measured, and the electrical resistance (AC resistance) retention rate was calculated. 1.
As can be seen from FIG. 1, the regression line of y = -0.4501x + 0.9873 is obtained in the accelerated deterioration test at 40 ° C. by the least squares method, where y is the electrical resistance retention rate and x is the absorbance at 600 nm. was taken. The correlation coefficient ^R2 was 0.84.
On the other hand, the same Cl-containing anion-exchange membrane was installed in an electrodialysis apparatus that produces industrial water by desalinating underground brine, and electrodialysis was performed for one year under the condition that the liquid temperature in the tank did not exceed 40 ° C ( hereinafter referred to as "in-situ membrane"). Visual observation revealed that part of the anion membrane had deteriorated to a red color due to water decomposition. A sample was cut out from this portion and the absorbance at 600 nm and the AC resistance retention were measured. The absorbance was 0.27 and the AC resistance retention was 91%. However, from the regression line in FIG. 1, the AC resistance retention rate was estimated to be 87% when the absorbance was 0.27. There was an error of about 4% and they were in general agreement.

<Example 2>
In the deterioration acceleration test of Example 1, the Young's modulus was measured instead of measuring the AC resistance of the film, and the relationship between the absorbance and the Young's modulus was obtained. The results are shown in FIG. . As can be seen from FIG. 2, in the accelerated deterioration test at 40° C., a regression line of y=−0.5207x+0.9755 was obtained for the relationship between the absorbance for visible light (600 nm) and Young's modulus.
Next, since the in-situ absorbance of the Cl-containing anion exchange membrane obtained in Example 1 was 0.27, the Young's modulus was estimated to be 83% from the regression line. The Young's modulus of the actual in-situ film was 79%, which was in general agreement.

<Example 3>
The accelerated deterioration test of Example 1 was carried out in the same manner, except that instead of measuring the AC resistance of the membrane, the transference number was measured, and the relationship between the absorbance and the transference number was obtained. The results are shown in FIG. . As can be seen from FIG. 3, in the accelerated deterioration test at 40° C., a regression line of y=−0.2407x+1.0023 was obtained for the relationship between absorbance and transport number for visible light (600 nm).
Next, since the absorbance of the in-situ membrane of the Cl-containing anion exchange membrane obtained in Example 1 was 0.27, the transference number retention was estimated to be 94% from the regression line. The transference number retention rate of the actual in-situ membrane was 90%, which was in general agreement.

<Example 4>
The accelerated deterioration test of Example 1 was performed in the same manner, except that instead of measuring the AC resistance of the film, the water content was measured and the relationship between the absorbance and the water content was obtained. The results are shown in FIG. . As can be seen from FIG. 4, in the accelerated deterioration test at 40° C., a regression line of y=−0.2404x+1.0065 was obtained for the relationship between the absorbance for visible light (600 nm) and the water content.
Next, since the absorbance of the in-situ membrane of the Cl-containing anion exchange membrane obtained in Example 1 was 0.27, the water content retention rate was estimated to be 94% from the regression line. The moisture content retention rate of the actual in-situ membrane was 92%, which was in general agreement.

<Example 5>
In the accelerated deterioration test of Example 1, the reflectance is measured instead of the absorbance for visible light, and the relationship between the reflectance for visible light (600 nm) and the electrical resistance retention rate is obtained. The results are shown in FIG.
As can be seen from FIG. 5, a regression line of y = 0.5897x + 0.3871 was obtained in the accelerated deterioration test at 40 ° C. by the least squares method, where y is the electrical resistance retention rate and x is the 600 nm reflectance. was taken. The correlation coefficient ^R2 was 0.86.
The in-situ reflectance of the Cl-containing anion exchange membrane obtained in Example 1 was estimated to be 80%, and the electrical resistance retention was estimated to be 86%. The electrical resistance retention of the in-situ membrane was 91%, so there was an error of about 5%.

<Example 6>
The accelerated deterioration test of Example 5 was performed in the same manner, except that the temperature of the NaOH aqueous solution was set at 60° C., and the results are shown in FIG. As can be seen from FIG. 6, when the results of the accelerated deterioration test at 60° C. are added, a regression line of y = 0.5992x + 0.2815 is obtained for the relationship between the reflectance for visible light (600 nm) and the electrical resistance retention rate. was taken. The correlation coefficient R ² was 0.74, indicating a decrease in accuracy.
As a result, from this regression line, the electrical resistance retention rate for a reflectance of 80% is 76%, which is a difference of about 10% when compared with the result (86%) of Example 5 in which the accelerated deterioration test was performed at 40 ° C. became. The electrical resistance of the experiment at high temperature tends to be low, and the value was lower than the value estimated at 40°C. However, if the deterioration is severe, the x-axis reflectance will be a low value, so if the calibration curve is not made over time, the tendency of deterioration can be fully grasped, and it is meaningful as a simple judgment method. rice field.

<Example 7>
The accelerated deterioration test of Example 5 was carried out in the same manner except that the Young's modulus was measured instead of measuring the AC resistance of the film, and the relationship between the reflectance and Young's modulus was obtained. The results are shown in FIG. rice field. As can be seen from FIG. 7, in the accelerated deterioration test at 40° C., a regression line of y=0.8017x+0.1907 was obtained for the relationship between the reflectance for visible light (600 nm) and Young's modulus.
Next, as shown in Example 5, the in-situ reflectance of the Cl-containing anion exchange membrane obtained in Example 1 was 80%, so the Young's modulus was estimated to be 83% from the regression line. . The Young's modulus of the actual in-situ film was 79%, which was in general agreement.

<Example 8>
In the accelerated deterioration test of Example 1, the chlorine intensity (fluorescent X-ray analysis) was measured instead of the absorbance for visible light, and the relationship between the chlorine intensity retention rate and the electrical resistance retention rate was determined in the same manner. and the results are shown in FIG. As can be seen from FIG. 8, in the accelerated deterioration test at 40° C., a regression line of y=2.3286x-1.3733 was obtained for the relationship between the chlorine strength retention rate and the electrical resistance retention rate.
The in-situ chlorine strength retention rate of the Cl-containing anion exchange membrane obtained in Example 1 was estimated to be 93%, and the electrical resistance retention rate was estimated to be 79%.

<Example 9>
In the deterioration acceleration test of Example 8, the Young's modulus was measured instead of measuring the AC resistance of the film, and the relationship between the chlorine strength retention rate and the Young's modulus was obtained. It was shown to. As can be seen from FIG. 9, in the accelerated deterioration test at 40° C., a regression line of y=2.9444x-2.0012 was obtained for the relationship between chlorine strength and Young's modulus.
The in-situ chlorine intensity retention of the Cl-containing anion exchange membrane obtained in Example 1 was estimated to be 93%, and the Young's modulus retention was estimated to be 74%.

Claims (6)

Prepare an unused polyvinyl chloride component-containing anion exchange membrane,
The anion-exchange membrane is brought into contact with an alkaline aqueous solution to perform a deterioration accelerated test, and the optical properties of the membrane with respect to visible light and the physical properties and/or electrochemical properties of the anion-exchange membrane are measured for each degree of deterioration. , preparing a calibration curve showing changes in physical properties and/or electrochemical properties of the anion exchange membrane with respect to changes in optical properties;
The optical properties of the polyvinyl chloride component-containing anion exchange membrane in use are measured with respect to visible light, and the physical properties and/or electrochemical properties of the anion exchange membrane in use are determined from the optical properties based on the calibration curve. A method for inspecting a polyvinyl chloride component-containing anion exchange membrane, characterized by: Prepare an unused polyvinyl chloride component-containing anion exchange membrane,
The anion-exchange membrane is brought into contact with an alkaline aqueous solution to perform a deterioration accelerated test, and the chlorine intensity and the physical properties and/or electrochemical properties of the anion-exchange membrane are measured by fluorescent X-ray intensity analysis of the membrane for each degree of deterioration. to prepare a calibration curve showing changes in physical properties and/or electrochemical properties of the anion exchange membrane with respect to changes in fluorescent X-ray intensity,
The fluorescent X-ray intensity of the polyvinyl chloride component-containing anion-exchange membrane in use is measured, and the physical properties and/or electrochemical properties of the anion-exchange membrane in use are determined from the measured fluorescent X-ray intensity based on the calibration curve. A method for inspecting a polyvinyl chloride component-containing anion exchange membrane, characterized by determining 2. The inspection method according to claim 1, wherein the optical property of the anion-exchange membrane with respect to visible light, which is measured for each degree of deterioration, is absorbance. 3. The inspection method according to claim 1, wherein mechanical strength or water content is determined as the physical property of the anion exchange membrane. 5. The inspection method according to claim 4 , wherein the mechanical strength for determining the physical properties of the anion exchange membrane is Young's modulus. 3. The inspection method according to claim 1, wherein electrical resistance or transference number is determined as the electrochemical property of the anion exchange membrane.

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