JP7465009B2 - Filtration Membrane - Google Patents

Description

Article 30, paragraph 2 of the Patent Act applies. (Part 1) Date of website posting: February 27, 2018 Website address: http://www3.scej.org/meeting/83a/pages/jp_apple-intellectual.html (Part 2) Date of holding: March 13, 2018 to March 15, 2018 (publication date: March 14, 2018) Name and location of the meeting: Society of Chemical Engineers, 83rd Annual Meeting, Kansai University, Senriyama Campus (3-3-35 Yamate-cho, Suita-shi, Osaka)

The present invention relates to a filtration membrane for filtering nano-sized solutes in a solution containing an organic solvent and the solute.

Nanofiltration separates molecules with a molecular weight cutoff (200-2000), which is intermediate between reverse osmosis and ultrafiltration. Generally, nanofiltration allows water to pass through an aqueous solution, but there is a demand for the development of an organic solvent nanofiltration membrane (OSN) that allows organic solvents to pass through in the pharmaceutical and petrochemical industries. OSN is effective for recovering and recycling organic solvents in the pharmaceutical manufacturing process, including the petrochemical industry, and can significantly reduce the cost of treating waste liquids that have been discarded up until now and the cost of organic solvents, making it a technology that enables a significant reduction in environmental load. However, existing membranes have low permeability coefficients and insufficient rejection rates, so there are problems such as the need for a huge membrane area, the need for energy to apply pressure, and the inclusion of undesirable substances on the permeation side. In particular, the molecular weight of lubricating oils (about 300) is relatively close to that of organic solvents, so
These problems become more pronounced.

Polymer membranes are widely used as organic solvent nanofiltration membranes, but they have problems such as low permeation flux (Non-Patent Document 1).

Chem. Rev. , 114, 10735-10806 (2014).

An object of the present invention is to provide a technique capable of more efficiently filtering nano-sized solutes in a solution containing an organic solvent and the solute.

In view of the above problems, the present inventors have conducted extensive research and found that nano-sized solutes in a solution containing an organic solvent and a solute can be filtered more efficiently by using a filtration membrane including a porous hydrophobic silica membrane and/or by a pervaporation separation method. Based on this finding, further research has led to the completion of the present invention.

［式中、Ｒ ^１ は炭素数１～５のアルキル基を示す。Ｒ ^２ 、Ｒ ^３ 及びＲ ^４ は同一又は異なって、炭素数１～４のアルキル基を示す］
である、項１ａ～１７ａのいずれかに記載の製造方法。
項１９ａ．
項１ａ～１８ａのいずれかに記載の製造方法で製造される、分離膜。
項２０ａ．
中空糸状である、項１９ａに記載の分離膜。 That is, the present invention includes the following aspects.
Item 1a.
A method for producing a separation membrane, comprising the steps of:
The separation membrane is a separation membrane for separating a nanosized solute in a solution containing an organic solvent and a solute,
the separation membrane comprises a porous hydrophobic silica membrane;
The method includes a step (A) of obtaining the porous hydrophobic silica membrane by mixing an alkoxysilane containing a hydrophobic group linked to a silicon atom, a surfactant, and a solvent, hydrolyzing and polymerizing the alkoxysilane, and then baking the resulting mixture.
A method for producing a separation membrane.
Item 2a.
The method according to Item 1a, wherein the surfactant is a cationic surfactant.
Item 3a.
The method according to Item 1a or 2a, wherein the surfactant is an alkyl ammonium or a salt thereof.
Item 4a.
Item 3a. The method according to Item 3a, wherein the alkyl ammonium or the salt thereof has 12 to 25 carbon atoms.
Item 5a.
The method according to Item 3a or 4a, wherein the alkyl ammonium or the salt thereof has 14 to 18 carbon atoms.
Item 6a.
The method according to any one of Items 1a to 5a, wherein the amount of the surfactant used per 100 mL of the solvent in the step (A) is 0.008 to 0.08 mol.
Item 7a.
The method according to any one of Items 1a to 6a, wherein the amount of the surfactant used per 100 mL of the solvent in the step (A) is 0.005 to 0.012 mol.
Item 8a.
The method according to any one of Items 1a to 7a, wherein the separation membrane further comprises a support, and the step (A) is carried out on the support.
Item 9a.
The method according to any one of items 1a to 8a, wherein the support is in the form of a hollow fiber.
Item 10a.
The method according to any one of Items 1a to 9a, wherein the separation membrane is in the form of a hollow fiber.
Item 11a.
The method according to any one of items 8a to 10a, wherein the support has an average pore size of 2 to 500 nm.
Item 12a.
The manufacturing method according to any one of Items 8a to 11a, wherein the support includes a support layer having an average pore diameter of 20 to 500 nm, and an intermediate layer having an average pore diameter of 2 to 10 nm disposed on the support layer.
Item 13a.
Item 12. The method according to item 12a, wherein the intermediate layer has a thickness of 0.2 to 5 μm.
Item 14a.
The method according to any one of Items 1a to 13a, wherein the porous hydrophobic silica membrane has an average pore size of less than 2 nm.
Item 15a.
The method according to any one of Items 1a to 14a, wherein the porous hydrophobic silica film has a thickness of 50 to 500 nm.
Item 16a.
The method according to any one of items 1a to 15a, wherein the molecular weight of the nano-sized solute is 200 to 1000.
Item 17a.
The method according to any one of items 1a to 16a, wherein the molecular weight of the nano-sized solute is 200 to 500.
Item 18a.
The alkoxysilane contains a hydrophobic group linked to a silicon atom represented by the following formula (1):

[In the formula, R ¹ represents an alkyl group having 1 to 5 carbon atoms. R ² , R ³ and R ⁴ may be the same or different and each represents an alkyl group having 1 to 4 carbon atoms.]
The method according to any one of Items 1a to 17a,
Item 19a.
A separation membrane produced by the production method according to any one of items 1a to 18a.
Item 20a.
Item 19. The separation membrane according to item 19a, which is in the form of a hollow fiber.

Item 1. A filtration membrane for filtering a nanosized solute in a solution containing an organic solvent and the solute, comprising a porous hydrophobic silica membrane.

Item 2. The filtration membrane according to Item 1, wherein the nano-sized solute has a molecular weight of 200 to 1,000.

Item 3. The filtration membrane according to Item 1 or 2, wherein the molecular weight of the nano-sized solute is 200 to 500.

Item 4. The filtration membrane according to any one of Items 1 to 3, wherein the porous hydrophobic silica membrane has an average pore size of less than 2 nm.

Item 5. The porous hydrophobic silica membrane has an average pore size of 0.1 to 0.9 nm.
5. A filtration membrane according to any one of claims 4 to 4.

Item 6. The filtration membrane according to any one of Items 1 to 5, wherein the porous hydrophobic silica membrane has a thickness of 50 to 500 nm.

Item 7. The filtration membrane according to any one of items 1 to 6, wherein the hydrophobic silica contains a hydrocarbon group.

Item 8. The filtration membrane according to any one of Items 1 to 7, further comprising a support, and the porous hydrophobic silica membrane is disposed on the support.

Item 9. The filtration membrane according to Item 8, wherein the average pore size of the support is 2 to 500 nm.

Item 10. The filtration membrane according to Item 8 or 9, wherein the support comprises a support layer having an average pore diameter of 20 to 500 nm, and an intermediate layer having an average pore diameter of 2 to 10 nm disposed on the support layer.

Item 11. The filtration membrane according to item 10, wherein the thickness of the intermediate layer is 0.2 to 5 μm.

Item 12. The filtration membrane according to any one of Items 1 to 11, for use in filtration by pervaporation separation.

Item 13. A membrane module comprising the filtration membrane described in any one of items 1 to 12.

Item 14. A membrane separation system including the membrane module described in Item 13.

Item 15. A filtration method, comprising filtering a nanosized solute in a solution containing an organic solvent and the solute, using the filtration membrane according to any one of Items 1 to 12.

Item 16. The filtration method according to Item 15, wherein the filtration is performed by pervaporation separation.

Item 17. A method for filtering a nanosized solute in a solution containing an organic solvent and the solute by pervaporation separation.

According to the present invention, nanosized solutes in a solution containing an organic solvent and a solute can be filtered more efficiently, particularly with, for example, a higher rejection and/or a higher permeability coefficient.

A method for forming a γ-alumina membrane on a hollow fiber zirconia support (Comparative Example 1) is outlined below. The filtration membrane prepared in Comparative Example 1 is used as a support, and a method (Example 1) for forming a porous hydrophobic silica membrane on the support is outlined below. 1 shows an outline of a nanofiltration test (Test Example 3-1). 1 shows an outline of a pervaporation separation test (Test Example 3-2). This is a comparison of the results of a methyl orange separation test of a polymer membrane previously reported (Chem. Rev., 114, 10736-10799 (2014)) and the results of Test Example 3-1. The hydrophobic silica membrane is the membrane of Example 1. FIG. 13 is a diagram showing the effect of temperature change on the results of a pervaporation separation test (Test Example 3-2). FIG. 13 is a diagram showing the effect of changes over time on the results of a permeation separation test (Test Example 3-2).

In this specification, the expressions "contain" and "include" are used interchangeably.
This includes the concepts of "consisting essentially of" and "consisting only of."

1. Embodiment 1
In one aspect, the present invention relates to a filtration membrane for filtering nano-sized solutes in a solution containing an organic solvent and a solute, the filtration membrane comprising a porous hydrophobic silica membrane (also referred to as the "filtration membrane of the present invention" in this specification), and a filtration method using the filtration membrane of the present invention (also referred to as the "filtration method 1 of the present invention" in this specification). This will be described below.

1-1. Porous hydrophobic silica film The porous hydrophobic silica film is not particularly limited as long as it is porous and is a film in which hydrophobic silica is the main component. Here, "main component" means that the content of hydrophobic silica is, for example, 80% by mass or more, preferably 90% by mass, based on 100% by mass of the porous hydrophobic silica film.
It indicates that the content is more preferably 95% by mass or more, and even more preferably 99% by mass or more.

The average pore size of the porous hydrophobic silica membrane is not particularly limited as long as it is capable of filtering nano-sized solutes. The average pore size can be appropriately set depending on the substance to be permeated and the substance to be blocked. For example, a pore size that is about half the size of the substance to be blocked and is about 1.5 times (e.g., about 1.3 to 1.8 times) the pore size that allows the solvent to pass sufficiently is exemplified. As an example of a specific embodiment, from the viewpoint of the rejection rate, permeability coefficient, etc., the average pore size is, for example, less than 2 nm, preferably 0.1 to 1.5 nm, more preferably 0.1 to 1 nm,
More preferably, it is 0.1 to 0.9 nm, even more preferably, it is 0.2 to 0.7 nm, and particularly preferably, it is 0.3 to 0.5 nm.

The average pore size can be measured by perm porometry. In this measurement, helium is used as the non-coagulating gas, and water and hexane are used as the coagulating gas. Coagulating gas and non-coagulating gas are supplied to the membrane, and the permeation flow rate of helium that permeates the membrane is measured by a soap film flowmeter. Water and hexane are supplied using a syringe pump so that the vapor pressure is calculated from the Kelvin formula (below) of Eq. (1). The geodetic temperature of the membrane is 315K.

Here, d is the Klvin diameter [m], ν is the molar volume [m ³ mol ⁻¹ ], and R is the gas constant [
Jmol ⁻¹ K ⁻¹ ], T is temperature [K], σ is surface tension [Nm ⁻¹ ], θ is contact angle [de
g.], P is the vapor pressure [Pa], and Ps is the saturated vapor pressure [Pa].

The thickness of the porous hydrophobic silica membrane is not particularly limited and can be appropriately set from the viewpoint of the mechanical strength of the filtration membrane of the present invention. As an example of a specific embodiment, from the viewpoint of rejection rate, permeability coefficient, etc., the thickness is, for example, 10 to 1000 nm, preferably 50 to 500, more preferably 50 to 400 nm, even more preferably 100 to 300, and even more preferably 150 to 200 nm.
It is 50 nm.

The thickness can be measured based on an image obtained by observing a cross section of the film under a microscope.

Hydrophobic silica is usually silica that contains hydrophobic functional group, and is not particularly limited as long as it is.Hydrophobic group can be, for example, hydrocarbon group.Hydrophobic group can be, for example, alkyl group that may be substituted with halogen atom, cycloalkyl group that may be substituted with halogen atom, aryl group that may be substituted with halogen atom, etc.

The alkyl group may be either linear or branched (preferably linear). The number of carbon atoms in the alkyl group is not particularly limited, and is, for example, 1 to 12, preferably 1 to 8, more preferably 2 to 5, even more preferably 3 to 4, and still more preferably 3. Specific examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-
Examples of such alkyl groups include butyl, isobutyl, tert-butyl, sec-butyl, n-pentyl, neopentyl, n-hexyl, 3-methylpentyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl and n-dodecyl groups.
Among these, n-propyl is particularly preferred. The alkyl group may be a fluorine atom,
It may be substituted with a halogen atom such as a chlorine atom, a bromine atom or an iodine atom.

The number of carbon atoms in the cycloalkyl group is not particularly limited and is, for example, 3 to 10. Specific examples of the cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, etc. The cycloalkyl group may be substituted with a halogen atom such as a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom.

The aryl group is not particularly limited, but preferably has 6 to 12 carbon atoms, more preferably 6 to 8. The aryl group may be either monocyclic or polycyclic (e.g., bicyclic, tricyclic, etc.), but is preferably monocyclic. Specific examples of the aryl group include:
Examples of the aryl group include a phenyl group, a naphthyl group, a biphenyl group, a pentalenyl group, an indenyl group, an anthranyl group, a tetracenyl group, a pentacenyl group, a pyrenyl group, a perylenyl group, a fluorenyl group, a phenanthryl group, etc., and preferably a phenyl group. The aryl group may be substituted with a halogen atom such as a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom.

Porous hydrophobic silica film can be manufactured by the method according to the method of preparing silica gel by sol-gel method.For example, porous hydrophobic silica film can be obtained by mixing the alkoxysilane that contains the hydrophobic group connected to silicon atom, surfactant and solvent, carrying out hydrolytic polycondensation of the alkoxysilane, and then calcining the mixture obtained.

The alkoxysilane is not particularly limited as long as it contains a hydrophobic group linked to a silicon atom. Examples of the alkoxysilane include those represented by the general formula (1):

[In the formula, R ¹ represents a hydrophobic group. R ² , R ³ and R ⁴ may be the same or different and each represent an alkyl group.]
Examples of the compound include compounds represented by the following formula:

The hydrophobic group represented by ^R1 is the same as the hydrophobic group explained above.

The alkyl groups represented by R ² , R ³ and R ⁴ include both linear and branched ones. The number of carbon atoms in the alkyl group is not particularly limited, and may be, for example, 1 to 6, preferably 1 to 6.
4, more preferably 1 to 2. Specific examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, a sec-butyl group, an n-pentyl group, a neopentyl group, an n-hexyl group, and a 3-methylpentyl group.

The amount of the alkoxysilane used is not particularly limited, but is, for example, 0.003 to 0.3 mol, preferably 0.01 to 0.1 mol, and more preferably 0.0 to 100 mL of the solvent.
It is 2 to 0.5 mol.

The surfactant is not particularly limited, and for example, cationic surfactants, anionic surfactants, nonionic surfactants, etc. can be widely used. Among these, cationic surfactants are preferable, and alkylammonium or its salts are more preferable. The surfactant contributes to the formation of pores after baking by interacting with the hydrophobic group of alkoxysilane or its hydrolyzate. From this viewpoint, the surfactant is preferably a C12 surfactant.
or more (preferably 12 to 25, more preferably 12 to 20, and even more preferably 14 to 18
, and even more preferably an alkyl group having 15 to 17 carbon atoms.

The amount of the surfactant used is not particularly limited, but may be, for example, 0.0
0.008 to 0.08 mol, preferably 0.002 to 0.03 mol, more preferably 0.
0.005 to 0.012 mol.

During the hydrolysis, it is preferable to add an acid such as nitric acid, hydrochloric acid, or sulfuric acid as a hydrolysis catalyst.

The solvent is not particularly limited as long as it contains water necessary for the hydrolysis of the alkoxide.
Typically, the solvent is a mixture of water and an organic solvent (eg, an alcohol such as ethanol).

The mixing time and mixing temperature are not particularly limited, and are, for example, 10 to 40° C. for 1 to 5 hours (preferably 2 to 4 hours), whereby the alkoxide is hydrolyzed.

The resulting mixture is applied to a suitable substrate as required and then baked. As the substrate, it is preferable to use a support as described below. By baking, the solvent is evaporated and the reaction between the remaining hydroxyl groups is promoted, thereby obtaining an amorphous silica film.

The coating onto the substrate is not particularly limited, and can be carried out according to or in accordance with a known method.
Examples of the coating method include a dip coating method, a spin coating method, and a spray coating method.

The baking temperature is not particularly limited as long as it is a temperature at which the evaporation of the solvent and the reaction between the remaining hydroxyl groups are promoted, and the hydrophobic groups are not removed.
, preferably 130 to 220°C, more preferably 160 to 220°C, and even more preferably 1
The calcination temperature is 70 to 190° C. The calcination time is appropriately set depending on the calcination temperature, and is not particularly limited. The time is, for example, 1 to 6 hours, and preferably 2 to 4 hours. After calcination, it is desirable to wash the membrane.

1-2. Layer structure of the filtration membrane The filtration membrane of the present invention is not particularly limited as long as it includes a porous hydrophobic silica membrane. Preferably, the filtration membrane of the present invention further includes a support. In this case, the porous hydrophobic silica membrane is
The support allows the thickness of the porous hydrophobic silica membrane to be made thinner while maintaining the mechanical strength of the filtration membrane of the present invention.

The material of the support is not particularly limited, and a wide variety of materials that can be used as supports for filtration membranes can be used. Examples of such materials include zirconia, alumina, silica, titania,
Magnesia and the like.

The average pore size of the support is not particularly limited, but is, for example, 2 to 500 nm, preferably 2 to 200 nm, and more preferably 2 to 100 nm, from the viewpoints of rejection rate, permeability coefficient, etc. The thickness of the support is not particularly limited, but is, for example, 50 to 30
0 μm, preferably 120 to 200 μm.

The layer structure of the support is not particularly limited. The support may be a single layer or a multi-layer structure. The support preferably has an average pore size of 20 to 500 nm.
The present invention comprises a support layer having an average pore size of 2 to 10 nm, and an intermediate layer having an average pore size of 2 to 10 nm disposed on the support layer.

The average pore size of the support layer is not particularly limited, but from the viewpoints of rejection rate, permeability coefficient, etc., it is preferably 20 to 200 nm, more preferably 20 to 100 nm, and further preferably 30 to 80
The thickness of the support layer is not particularly limited, but is, for example, 50 to 300 μm, and preferably 120 to 200 μm, from the viewpoints of rejection rate, transmission coefficient, etc. The material of the support layer is preferably zirconia.

The average pore size of the intermediate layer is not particularly limited, but is preferably 2 to 8 nm, more preferably 3 to 6 nm, from the viewpoints of rejection rate, permeability coefficient, etc. The thickness of the intermediate layer is not particularly limited, but is preferably 0.2 to 5 μm, more preferably 0.5 to 3 μm, from the viewpoints of permeability coefficient, etc.
, and more preferably 0.7 to 2 μm. The material of the intermediate layer is preferably alumina.

The support such as the support layer and the intermediate layer can be formed according to or in accordance with a known method.
These are, for example, as previously reported (Adv. Funct. Mater. 27 (2017) 160
4311. , Journal of Membrane Science, 290 (20
07) 138-145, etc.

1-3. Uses The filtration membrane of the present invention is used to filter a nano-sized solute in a solution containing an organic solvent and the solute.

The organic solvent is not particularly limited, but examples thereof include alcohols such as methanol and ethanol, toluene, methyl ethyl ketone, acetone, ethyl acetate, 1-methyl, 2-pyrrolidone,
Examples of the organic solvent include isopropanol, n-heptane, n-hexane, dimethylformamide, and tetrahydrofuran. The molecular weight of the organic solvent is, for example, 20 to 150, preferably 30 to 120.
, and more preferably 30 to 100.

The nano-sized solute is not particularly limited, but examples thereof include solutes having a molecular weight of 200 to 1000, preferably 200 to 500, more preferably 200 to 400, and even more preferably 250 to 400. Examples of the nano-sized solute include lubricating oils, more specifically, alpha olefin oligomers, polybutene, diesters, phosphate esters, silicate esters, and the like.

Examples of the filtration method include nanofiltration and pervaporation separation. The filtration membrane of the present invention can achieve a higher rejection rate and/or a higher permeability coefficient when used in any of the methods. These methods can be carried out according to or in accordance with conventionally known methods. The filtration membrane of the present invention can be used for filtration by pervaporation separation to more significantly increase the permeability coefficient.

The supply temperature during filtration by the pervaporation separation method is not particularly limited.
° C. or higher, preferably 15 ° C. or higher, more preferably 30 ° C. or higher, even more preferably 50 ° C. or higher, and even more preferably 60 ° C. or higher. By setting the temperature higher, the permeability coefficient can be increased more significantly. The upper limit is not particularly limited, and can be appropriately set based on the operating pressure and the vapor pressure of the organic solvent according to the boiling point of the organic solvent. The upper limit is, for example, 200 ° C., 150 ° C., 100 ° C., or 80 ° C.

The filtration membrane of the present invention can be used to filter nanosized solutes in a solution containing an organic solvent and the solute to achieve a higher rejection and/or a higher permeability coefficient.

The permeability coefficient is, for example, 0.1 Lm ⁻² h ⁻¹ bar ⁻¹ or more, preferably 0.15 Lm −2 h −1 bar −1 or ^more.
When the pervaporation separation method is used, the permeability coefficient is, for example, 1 Lm ^-2 h ^-1 bar ^-1 or more, preferably ⁵ Lm ^-2 h ^-1 bar ^-1 or more, more preferably 10 Lm ^-2 h ^-1 bar ^-1 or more, and even more preferably 20 Lm ^-2 h ^-1 bar ^-1 or ^more .
The permeability coefficient is preferably ¹⁰⁰⁰ Lm ^-2 h ^-1 bar-1 or more, more preferably 40 Lm-2 h-1 bar ^-1 or more, and particularly preferably 60 Lm ^-2 h ^-1 bar ^{-1 or} more. There is no particular upper limit to the permeability coefficient.
00Lm ^-2 h ^-1 bar ^-1 .

The permeability coefficient can be calculated based on the solute concentration on the feed side and the solute concentration on the permeate side according to the following formula:

The rejection rate is, for example, 90% or more, preferably 95% or more, more preferably 98% or more, even more preferably 99% or more, still more preferably 99.5% or more, and particularly preferably 99% or more.
.8% or more, and usually less than 100%.

The rejection can be calculated based on the feed-side solute concentration and the permeate-side solute concentration according to the following formula:

1-4. Membrane Module and Membrane Separation System In one aspect, the present invention relates to a membrane module including the filtration membrane of the present invention, and a membrane separation system including the membrane module.

The type of membrane module is not particularly limited, and examples thereof include a spiral module, a pleated module, a monolith module, a tubular module, etc. The membrane module includes, in addition to the filtration membrane of the present invention, appropriate components constituting the module.

In addition to the membrane module, the membrane separation system includes other components and devices that make up the membrane separation system. For example, in the filtration mode, it includes a pressurizer, a multi-stage system, and a system for returning non-permeated liquid to the previous stage in the case of a multi-stage system. In the PV mode, it includes a supply device (can be continuous or batch), a multi-stage system in the case of a continuous system, a system for recycling non-permeated liquid in the case of a multi-stage system, a vacuum device, and a device for cooling and recovering permeated vapor.

EMBODIMENT 2
The present invention, in one aspect, also relates to a method of filtering a nanosized solute in a solution comprising an organic solvent and the solute by pervaporation.

The definitions of each component are the same as those in the first embodiment. In addition to the filtration membrane of the present invention, known filtration membranes can be used in this method. Known filtration membranes include, for example, polydimethylsiloxane, polytetrafluoroethylene, ethylene-propylene-diene terpolymer, polyurethaneurea, poly(ether-block amide),
Examples of the membrane include polymer membranes such as poly(1-trimethylsilyl-1-propyne), polypropylene, polyaniline, polyimide, polyethersulfone, polyacrylonitrile, polyamide, dimethylformamide, and polyethyleneimine, and inorganic membranes using titania, alumina, silica, and the like.

The present invention will be described in detail below based on examples, but the present invention is not limited to these examples.

Comparative Example 1. Preparation of a filtration membrane including a γ-alumina membrane A γ-alumina membrane was formed on a hollow fiber zirconia support. Specifically, this was carried out as follows. The outline of this formation method is shown in FIG.

1.75 g of polyvinyl alcohol and 50 mL of 0.05 M aqueous nitric acid solution were mixed to obtain a 90
The mixture was refluxed at 0.8° C. for 2 hours. 25 mL of a boehmite solution (concentration: 0.8 mol/L) was added thereto, and ultrasonic stirring was performed for 20 minutes to obtain a solution for forming a γ-alumina membrane.
r. 27 (2017) 1604311.) was immersed in a γ-alumina membrane forming solution at a speed of 2 mm/s and held for 20 seconds, then pulled out of the solution at a speed of 1 mm/s. After drying at room temperature for 3 hours, it was fired at 600 ° C for 24 hours to obtain a γ-alumina membrane.

Example 1. Preparation of a filtration membrane containing a porous hydrophobic silica membrane Using the filtration membrane prepared in Comparative Example 1 as a support, a porous hydrophobic silica membrane was formed on the intermediate layer (γ-alumina membrane) of the support. Specifically, this was carried out as follows. The outline of this formation method is shown in Figure 2. 25 mL of ethanol, 7.5 mL of 1 M aqueous nitric acid solution, 0.01 mol of N-propyltrimethoxysilane, and 0.01 mol of cetyltrimethylammonium bromide were used.
The filtration membrane prepared in Comparative Example 1 was immersed in the porous hydrophobic silica membrane forming solution for 60 seconds, and then pulled out of the solution at a speed of 1 mm/s.
After baking at 80° C. for 3 hours, the film was immersed in ethanol for 24 hours and washed with a large amount of ethanol to obtain a porous hydrophobic silica film.

Test Example 1. Measurement of membrane thickness The cross section of the filtration membrane prepared in Example 1 was observed (magnification: 20,000 times) with an FE-SEM (field emission scanning electron microscope) (manufactured by Hitachi, Ltd., product name S-4800), and the thickness of each layer was measured based on the obtained observation image. As a result, the thickness of the γ-alumina membrane was about 1 μm, and the thickness of the porous hydrophobic silica membrane was about 200 nm.

Test Example 2. Measurement of average pore size For the filtration membrane prepared in Comparative Example 1 and the filtration membrane prepared in Example 1, the pore size distribution of each of the γ-alumina membrane and the porous hydrophobic silica membrane was measured by perm porometry. In this test example, helium was used as the non-coagulating gas, and water and hexane were used as the coagulating gas. The coagulating gas and the non-coagulating gas were supplied to the membrane, and the permeation flow rate of helium that permeated the membrane was measured by a soap film flowmeter. Water and hexane were supplied using a syringe pump so that the vapor pressure was calculated from the Kelvin formula (below) of Eq. (1). The geodetic temperature of the membrane was 315K.

Here, d is the Klvin diameter [m], ν is the molar volume [m ³ mol ⁻¹ ], and R is the gas constant [
Jmol ⁻¹ K ⁻¹ ], T is temperature [K], σ is surface tension [Nm ⁻¹ ], θ is contact angle [de
g.], P is the vapor pressure [Pa], and Ps is the saturated vapor pressure [Pa].

As a result, the average pore diameter of the γ-alumina membrane was 4.1 nm, and the average pore diameter of the porous hydrophobic silica membrane was 0.43 nm.

Test Example 3: Permeation test
Test Example 3-1. Nanofiltration (NF) test Ethanol was used as the organic solvent, and methyl orange (molecular weight 327, molecular diameter approximately 1
A 35 μM solution of methyl orange was prepared using a spectrophotometer (nm). A membrane (Comparative Example 1 or Example 1) was connected to a pressure vessel, and 6 bar of pressure was applied from the top of the pressure vessel. The permeate was collected in a beaker from the bottom of the pressure vessel. The concentrations on the supply side and the permeate side were measured using an absorbance meter (ASUV 6300-PC,
The measurement was performed using a 300-millimeter wave length measuring instrument (manufactured by AS ONE Corporation). The outline of this test is shown in Figure 3.

The permeance and rejection were calculated according to the following formulas.

Test Example 3-2. Pervaporation separation test Using ethanol as the organic solvent and methyl orange (molecular weight 327) as the solute,
A 35 μM solution of methyl orange was prepared. A membrane (Comparative Example 1 or Example 1) was immersed in the solution, and the inside of the membrane was depressurized to about 5.0 Pa using a vacuum pump. The permeated gas was collected as a liquid in a cold trap, and the weight of the permeated liquid was measured. The concentration on the supply side was measured using an absorption spectrometer (ASUV 63
The measurement was performed using a 00-PC (manufactured by AS ONE Corporation). The outline of this test is shown in Figure 4.

The feed temperature was set to 20, 30, 50, 60, and 70° C., and the solution was collected for 30 minutes at each temperature to examine the effect of temperature change on separation performance. After the test at 70° C., the solution was continued to be collected every 30 minutes for 270 minutes to examine the effect of change over time.

The permeability coefficient and rejection rate were calculated in the same manner as in Test Example 3-1.

Test Example 3-3. Results <Result 1>
The results of the NF test performed on the membrane of Comparative Example 1 (γ-alumina) and the membrane of Example 1 (H-silica) are shown in Table 1.

The membrane of Comparative Example 1 showed a low rejection rate of 13.6%, while the membrane coated with the silica layer showed a high rejection rate of 99.9% or more. The permeability coefficient was lower than that of the test performed with only the intermediate layer, but it was higher than that of the previous report shown in FIG. 5 (Chem. Rev., 114, 10735-10806).
When compared with the methyl orange separation test of the polymer membrane in (2014), it can be seen that the trade-off relationship has been overcome.

<Result 2>
The results of the pervaporation separation test (supply temperature 20° C.) are shown in Table 2. The effects of temperature and time are shown in FIGS.

As shown in Table 2, the permeability coefficient increased significantly by performing pervaporation separation. Also, from FIG. 6, it was found that the permeation flux increased with increasing temperature at 20 to 70°C. Also, from FIG. 7, it was found that the permeation flux gradually decreased with time and became constant after 270 minutes had passed. However, when the membrane was washed after 270 minutes had passed and subjected to the test again, it was found to show the same level of performance.

Claims (20)

A method for producing a separation membrane, comprising the steps of:
The separation membrane is a separation membrane for separating a nanosized solute in a solution containing an organic solvent and a solute,
the separation membrane comprises a porous hydrophobic silica membrane;
The method includes a step (A) of obtaining the porous hydrophobic silica membrane by mixing an alkoxysilane containing a hydrophobic group linked to a silicon atom, a surfactant, and a solvent, hydrolyzing and polymerizing the alkoxysilane, and then baking the resulting mixture at 100 to 250° C .;
The alkoxysilane contains a hydrophobic group linked to a silicon atom represented by the following formula (1):

[In the formula, R ¹ represents an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, or an aryl group having 6 to 8 carbon atoms. R ² , R ³ and R ⁴ may be the same or different and each represents an alkyl group having 1 to 6 carbon atoms.]
That is,
A method for producing a separation membrane. The method according to claim 1, wherein the surfactant is a cationic surfactant. The method according to claim 1 or 2, wherein the surfactant is an alkyl ammonium or a salt thereof. The method according to claim 3, wherein the alkyl ammonium or its salt has 12 to 25 carbon atoms. The method according to claim 3 or 4, wherein the alkyl ammonium or its salt has 14 to 18 carbon atoms. The method according to any one of claims 1 to 5, wherein the amount of the surfactant used per 100 mL of the solvent in step (A) is 0.008 to 0.08 mol. The method according to any one of claims 1 to 6, wherein the amount of the surfactant used per 100 mL of the solvent in step (A) is 0.005 to 0.012 mol. The method according to any one of claims 1 to 7, wherein the separation membrane further comprises a support, and step (A) is carried out on the support. The manufacturing method according to claim 8, wherein the support is in the form of a hollow fiber. The manufacturing method according to any one of claims 1 to 9, wherein the separation membrane is in the form of a hollow fiber. The manufacturing method according to claim 8 or 9, wherein the average pore diameter of the support is 2 to 500 nm. The manufacturing method according to any one of claims 8, 9 and 11, wherein the support comprises a support layer having an average pore diameter of 20 to 500 nm, and an intermediate layer having an average pore diameter of 2 to 10 nm disposed on the support layer. The manufacturing method according to claim 12, wherein the thickness of the intermediate layer is 0.2 to 5 μm. The method according to any one of claims 1 to 13, wherein the average pore size of the porous hydrophobic silica membrane is less than 2 nm. The manufacturing method according to any one of claims 1 to 14, wherein the thickness of the porous hydrophobic silica film is 50 to 500 nm. The method according to any one of claims 1 to 15 , wherein the firing temperature in the step (A) is 130 to 220°C . The manufacturing method according to any one of claims 1 to 16, wherein the molecular weight of the nanosized solute is 200 to 500. The method according to any one of claims 1 to 17, wherein in formula (1) , R ¹ is an alkyl group having 1 to 8 carbon atoms, and R ² , R ³ and R ⁴ are the same or different and are alkyl groups having 1 to 6 carbon atoms. A separation membrane manufactured by the manufacturing method described in any one of claims 1 to 18. The separation membrane according to claim 19, which is in the form of a hollow fiber.