JP7219440B2 - filtration membrane - Google Patents

Description

Application of Article 30, Paragraph 2 of the Patent Law (Part 1) Posting date of website February 27, 2018 Website address http://www3. scej. org/meeting/83a/pages/jp_appl-intellectual. html (Part 2) Date March 13th, 2018 to March 15th, 2018 (Published on March 14th, 2018) Meeting name, venue The 83rd Annual Meeting of the Society of Chemical Engineers, Kansai University, Senriyama Campus (Osaka) 3-3-35 Yamate-cho, Suita City)

The present invention relates to filtration membranes and the like for filtering nano-sized solutes in solutions containing organic solvents and solutes.

Nanofiltration separates the molecular weight cutoff (200-2000), which is an intermediate size between reverse osmosis and ultrafiltration, and generally allows water to permeate from an aqueous solution, but in the pharmaceutical and petrochemical industries There is a desire to develop organic solvent nanofiltration membranes (OSNs) that are permeable to organic solvents. Starting with the petrochemical industry, OSN is effective in recovering and recycling organic solvents in the pharmaceutical manufacturing process. It is a technology that enables reduction. However, existing membranes have low permeation coefficients and do not have sufficient rejection, so there are problems such as the need for a huge membrane area, the energy required for pressurization, and the contamination of undesirable substances on the permeation side. There is In particular, since the molecular weight of lubricating oil (approximately 300) is relatively close to that of organic solvents, these problems become more pronounced.

Polymer membranes are often used as organic solvent nanofiltration membranes. However, polymer membranes 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 solutes.

As a result of intensive research in view of the above problems, the present inventors performed filtration using a filtration membrane containing a porous hydrophobic silica membrane and / or performed filtration by a pervaporation separation method to obtain an organic solvent and We have found that nano-sized solutes in solutions containing solutes can be more efficiently filtered. As a result of further research based on this knowledge, the present invention was completed.

That is, the present invention includes the following aspects.

Section 1. Filtration membranes for filtering nano-sized solutes in solutions containing organic solvents and solutes, comprising porous hydrophobic silica membranes.

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

Section 4. 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. Item 5. The filtration membrane according to any one of Items 1 to 4, wherein the porous hydrophobic silica membrane has an average pore size of 0.1 to 0.9 nm.

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

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

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

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

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

Item 12. Item 12. The filtration membrane according to any one of Items 1 to 11, which is used for filtration by pervaporation.

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

Item 14. Item 14. A membrane separation system comprising the membrane module according to Item 13.

Item 15. Item 13. A filtration method comprising filtering a nano-sized solute in a solution containing an organic solvent and a solute using the filtration membrane according to any one of Items 1 to 12.

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

Item 17. A filtration method comprising filtering a nano-sized solute in a solution containing an organic solvent and a solute by pervaporation.

According to the present invention, nano-sized solutes in solutions containing organic solvents and solutes can be filtered more efficiently, in particular with, for example, higher rejection and/or higher permeability coefficients. .

An outline of a method of forming a γ-alumina membrane on a hollow fiber zirconia support (Comparative Example 1) is shown. An outline of a method (Example 1) of forming a porous hydrophobic silica membrane on the support using the filtration membrane prepared in Comparative Example 1 is shown. An outline of the nanofiltration test (Test Example 3-1) is shown. An outline of the pervaporation separation test (Test Example 3-2) is shown. Fig. 2 is a diagram comparing the results of a methyl orange separation test of a polymer membrane in a previous report (Chem. Rev., 114, 10736-10799 (2014)) with the results of Test Example 3-1. The hydrophobic silica membrane is the membrane of Example 1. FIG. 3 is a diagram showing the effect of temperature change on the results of a pervaporation separation test (Test Example 3-2). FIG. 3 is a diagram showing the effect of change over time on the results of a permeation separation test (Test Example 3-2).

As used herein, the expressions "contain" and "include" include the concepts "contain", "include", "consist essentially of" and "consist only of".

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

1-1. Porous Hydrophobic Silica Membrane The porous hydrophobic silica membrane is not particularly limited as long as it is porous and mainly composed of hydrophobic silica. Here, the term “main component” means that the content of hydrophobic silica is, for example, 80% by mass or more, preferably 90% by mass or more, more preferably 95% by mass, relative to 100% by mass of the porous hydrophobic silica membrane. % or more, preferably 99% or more by mass.

The average pore size of the porous hydrophobic silica membrane is not particularly limited as long as it can filter nano-sized solutes. The average pore size can be appropriately set according to the substance to be permeated and the substance to be prevented from permeating. For example, the pore diameter is about half of the substance to be blocked and about 1.5 times (for example, about 1.3 to 1.8 times) the pore diameter through which the solvent can sufficiently pass. As a specific example, from the viewpoint of rejection, transmission coefficient, etc., it is less than 2 nm, preferably 0.1 to 1.5 nm, more preferably 0.1 to 1 nm, further preferably 0.1 to 0.9 nm. , more preferably 0.2 to 0.7 nm, particularly preferably 0.3 to 0.5 nm.

In addition, the average pore diameter can be measured by perm porometry. In this measurement, helium is used as the non-cohesive gas, and water and hexane are used as the cohesive gas. A coherent gas and a non-coherent gas are supplied to the membrane, and the permeation flow rate of helium passing through the membrane is measured with a soap film flowmeter. Water and hexane are Eq. Supply using a syringe pump so as to achieve the vapor pressure calculated from the Kelvin formula (below) of (1). The geodetic temperature of the membrane is carried out at 315K.

where d is the Klvin diameter [m], ν is the molar volume [m ³ mol ⁻¹ ], R is the gas constant [Jmol ⁻¹ K ⁻¹ ], T is the temperature [K], σ is the surface tension [Nm ^{− 1} ], θ is the contact angle [deg. ], 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, transmission coefficient, etc., the be.

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

Hydrophobic silica is generally silica containing a hydrophobic functional group, and is not particularly limited as far as it is concerned. Hydrophobic groups include, for example, hydrocarbon groups. Examples of the hydrocarbon group include alkyl groups optionally substituted with halogen atoms and the like, cycloalkyl groups optionally substituted with halogen atoms and the like, and aryl groups optionally substituted with halogen atoms and the like.

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

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

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

The porous hydrophobic silica membrane can be produced by a method according to the method for producing silica gel by the sol-gel method. For example, a porous hydrophobic silica film can be prepared by mixing an alkoxysilane containing a hydrophobic group linked to a silicon atom, a surfactant, and a solvent, hydrolyzing the alkoxysilane, and then calcining the resulting mixture. can be obtained by

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

[In the formula: R ¹ represents a hydrophobic group. R ² , R ³ and R ⁴ are the same or different and represent an alkyl group. ]
The compound represented by is mentioned.

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

The amount of alkoxysilane used is not particularly limited, but is, for example, 0.003 to 0.3 mol, preferably 0.01 to 0.1 mol, more preferably 0.02 to 0.5 mol, per 100 mL of solvent.

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 preferred, and alkylammonium or salts thereof are more preferred. Surfactants contribute to the formation of pores after firing by interacting with the hydrophobic groups of the alkoxysilane or its hydrolyzate. From this point of view, the surfactant preferably contains 12 or more carbon atoms (preferably 12 to 25, more preferably 12 to 20, still more preferably 14 to 18, still more preferably 15 to 17 alkyl groups). .

The amount of surfactant used is not particularly limited, but is, for example, 0.0008 to 0.08 mol, preferably 0.002 to 0.03 mol, more preferably 0.005 to 0.012 mol, per 100 mL of the solvent. .

At the time of hydrolysis, an acid such as nitric acid, hydrochloric acid, sulfuric acid, etc. is preferably added as a hydrolysis catalyst.

The solvent is not particularly limited as long as it contains water necessary for hydrolysis of the alkoxide. The solvent is typically 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). This hydrolyzes the alkoxide.

The obtained mixed solution is applied to a suitable base material as necessary, and then baked. As the substrate, it is preferable to use the support described later. The baking evaporates the solvent and promotes the reaction between the remaining hydroxyl groups to obtain an amorphous silica film.

Application to the substrate is not particularly limited, and can be carried out according to or according to known methods. Examples of coating methods include dip coating, spin coating, and spray coating.

The baking temperature is not particularly limited as long as it is a temperature that promotes the evaporation of the solvent and the reaction between the remaining hydroxyl groups and does not remove the hydrophobic groups. The temperature is, for example, 100 to 250°C, preferably 130 to 220°C, more preferably 160 to 220°C, still more preferably 170 to 190°C. The firing time is appropriately set depending on the firing temperature and is not particularly limited. The time is, for example, 1 to 6 hours, preferably 2 to 4 hours. After firing, it is desirable to wash the film.

1-2. Layer Structure of Filtration Membrane The filtration membrane of the present invention is not particularly limited as long as it contains a porous hydrophobic silica membrane. Preferably, the filtration membrane of the invention further comprises a support. In this case, a porous hydrophobic silica membrane is placed on a support. The support makes it possible to make the film thickness of the porous hydrophobic silica membrane thinner while maintaining the mechanical strength of the filtration membrane of the present invention.

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

The average pore diameter of the support is not particularly limited, but is, for example, 2 to 500 nm, preferably 2 to 200 nm, more preferably 2 to 100 nm, from the viewpoint of rejection, permeability coefficient and the like. The thickness of the support is not particularly limited, but is, for example, 50 to 300 μm, preferably 120 to 200 μm, from the viewpoint of rejection, transmission coefficient and the like.

The layer structure of the support is not particularly limited. The support may consist of a single layer or may consist of multiple layers. The support preferably comprises a support layer with an average pore size of 20-500 nm and an intermediate layer with an average pore size of 2-10 nm disposed on the support layer.

The average pore diameter of the support layer is not particularly limited, but is preferably 20 to 200 nm, more preferably 20 to 100 nm, still more preferably 30 to 80 nm from the viewpoint of rejection, permeability coefficient, and the like. The thickness of the support layer is not particularly limited, but is, for example, 50 to 300 μm, preferably 120 to 200 μm, from the viewpoint of rejection, transmission coefficient and the like. The material of the support layer is preferably zirconia.

Although the average pore diameter of the intermediate layer is not particularly limited, it is preferably 2 to 8 nm, more preferably 3 to 6 nm, from the viewpoint of rejection, permeability coefficient and the like. Although the thickness of the intermediate layer is not particularly limited, it is preferably 0.2 to 5 μm, more preferably 0.5 to 3 μm, still more preferably 0.7 to 2 μm from the viewpoint of permeability coefficient and the like. The material of the intermediate layer is preferably alumina.

Supports such as support layers and intermediate layers can be formed according to or according to known methods. These can be formed, for example, according to previous reports (Adv. Funct. Mater. 27 (2017) 1604311., Journal of Membrane Science, 290 (2007) 138-145, etc.).

1-3. Applications The filtration membranes of the present invention are used to filter nano-sized solutes in solutions containing organic solvents and solutes.

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

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

Filtration methods include, for example, a nanofiltration method, a pervaporation method, and the like. The filtration membrane of the present invention can achieve a higher rejection rate and/or a higher permeability coefficient in any method. These methods can be carried out according to or according to conventionally known methods. INDUSTRIAL APPLICABILITY The filtration membrane of the present invention can significantly increase the permeability coefficient by using it for filtration by the pervaporation method.

There is no particular restriction on the supply temperature during filtration by the pervaporation method. The temperature is, for example, 5° 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 transmission coefficient can be increased more significantly. The upper limit is not particularly limited, and can be appropriately set according to the boiling point of the organic solvent, based on the operating pressure and the vapor pressure of the organic solvent. The upper limits are, for example, 200°C, 150°C, 100°C and 80°C.

Higher rejection and/or higher permeability coefficients can be achieved by filtering nano-sized solutes in solutions containing organic solvents and solutes using the filtration membranes of the present invention.

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 employed, 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, more preferably 20 Lm ^-2 h ^-1 bar ^-1 or more, still more preferably 40 Lm ^-2 h ^-1 bar ^-1 or more, and particularly preferably 60 Lm ^-2 h ^-1 bar ^-1 or more. The upper limit of the permeability coefficient is not particularly limited, and is, for example, 100 Lm ^-2 h ^-1 bar ^-1 .

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

The blocking rate is, for example, 90% or higher, preferably 95% or higher, more preferably 98% or higher, still more preferably 99% or higher, still more preferably 99.5% or higher, particularly preferably 99.8% or higher, Usually less than 100%.

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

1-4. Membrane Module, 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 spiral type modules, pleated type modules, monolith type modules, tube type modules and the like. The membrane module includes parts constituting the module as appropriate in addition to the filtration membrane of the present invention.

The membrane separation system includes parts and devices that constitute the membrane separation system in addition to the membrane module. For example, in the case of filtration mode, it includes a pressurizer, a multi-stage system, etc., and a system for returning non-permeable liquid to the previous stage in the case of multi-stage. In the case of PV mode, a supply device (continuous or batch), etc., in the case of continuous, multi-stage system, etc., in the case of multi-stage, recycling system for recycling liquid that did not permeate, vacuum device, cooling and permeating vapor Including recovery equipment.

Embodiment 2
The invention also relates, in one aspect thereof, to a filtration method comprising filtering a nano-sized solute in a solution comprising an organic solvent and the solute by pervaporation.

The definition of each configuration is the same as the definition in the first embodiment. As the filtration membrane used in the present method, well-known filtration membranes can be mentioned in addition to the filtration membrane of the present invention. Examples of known filtration membranes include polydimethylsiloxane, polytetrafluoroethylene, ethylene-propylene-diene terpolymer, polyurethane urea, poly(ether-block amide), poly(1-trimethylsilyl-1-propyne), Films such as polymer films such as polypropylene, polyaniline, polyimide, polyethersulfone, polyacrylonitrile, polyamide, dimethylformamide, and polyethyleneimine, and inorganic films using titania, alumina, silica, and the like.

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

Comparative example 1. Preparation of Filtration Membrane Containing γ-Alumina Membrane A γ-alumina membrane was formed on a hollow fiber zirconia support. Specifically, it was carried out as follows. An outline of this formation method is shown in FIG.

1.75 g of polyvinyl alcohol and 50 mL of 0.05 M nitric acid aqueous solution were mixed and refluxed at 90° C. for 2 hours. 25 mL of a boehmite solution (concentration: 0.8 mol/L) was added thereto and ultrasonically stirred for 20 minutes to obtain a γ-alumina film forming solution. A hollow-fiber zirconia support (thickness: 158 μm, average pore size: about 50 nm, Adv. Funct. Mater. 27 (2017) 1604311.) was immersed in the γ-alumina film-forming solution at a rate of 2 mm/s for 20 seconds. After being held, it was pulled up from the solution at a speed of 1 mm/s. After drying at room temperature for 3 hours, it was calcined at 600° C. for 24 hours to obtain a γ-alumina film.

Example 1. Preparation of Filtration Membrane Containing 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, it was carried out as follows. An outline of this forming method is shown in FIG. 25 mL of ethanol, 7.5 mL of 1M nitric acid aqueous solution, 0.01 mol of N-propyltrimethoxysilane, and 0.008 mol of cetyltrimethylammonium bromide are mixed and stirred at room temperature for 3 hours to form a porous hydrophobic silica film. A solution (silica sol) was obtained. The filtration membrane prepared in Comparative Example 1 was immersed in the solution for forming a porous hydrophobic silica membrane, held for 60 seconds, and then pulled up from the solution at a speed of 1 mm/s. After baking at 180° C. for 3 hours, it 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. Film thickness measurement The cross section of the filtration membrane prepared in Example 1 was observed with an FE-SEM (field emission scanning electron microscope) (manufactured by Hitachi, Ltd., product name S-4800) (magnification: 20,000 times). The thickness of each layer was measured based on the images. As a result, the thickness of the γ-alumina film was about 1 μm, and the thickness of the porous hydrophobic silica film was about 200 nm.

Test example 2. Measurement of Average Pore Diameter Regarding the filtration membrane prepared in Comparative Example 1 and the filtration membrane prepared in Example 1, the pore diameter 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-cohesive gas, and water and hexane were used as the cohesive gas. A coherent gas and a non-coherent gas were supplied to the membrane, and the permeation flow rate of helium through the membrane was measured with a soap film flowmeter. Water and hexane are Eq. It was supplied using a syringe pump so that the vapor pressure calculated from the Kelvin equation (1) (below) was obtained. The geodetic temperature of the membrane was carried out at 315K.

where d is the Klvin diameter [m], ν is the molar volume [m ³ mol ⁻¹ ], R is the gas constant [Jmol ⁻¹ K ⁻¹ ], T is the temperature [K], σ is the surface tension [Nm ^{− 1} ], θ is the contact angle [deg. ], 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. Penetration test
Test Example 3-1. Nanofiltration (NF) test Ethanol was used as an organic solvent, and methyl orange (molecular weight: 327, molecular diameter: about 1 nm) was used as a solute to prepare a 35 μM solution of methyl orange. The membrane (Comparative Example 1 or Example 1) was connected to the pressure vessel and pressurized to 6 bar from the top of the pressure vessel. The permeated liquid was collected in a beaker from the bottom of the pressure vessel. The concentrations on the feed side and the permeate side were measured with an absorbance meter (ASUV 6300-PC, manufactured by As One). The outline of this test is shown in FIG.

A permeability coefficient (Permeance) and a rejection (Rejection) were calculated according to the following equations.

Test Example 3-2. Pervaporation Separation Test Ethanol was used as an organic solvent, and methyl orange (molecular weight: 327) was used as a solute to prepare a solution of 35 μM of methyl orange. The membrane (Comparative Example 1 or Example 1) was immersed in the solution, and the pressure inside the membrane was reduced to about 5.0 Pa with a vacuum pump. The permeated gas was recovered as a liquid with a cold trap, and the weight of the permeated liquid was measured. Feed-side concentration was measured with an absorbance meter (ASUV 6300-PC, manufactured by As One). The outline of this test is shown in FIG.

The supply temperature was set to 20, 30, 50, 60, and 70°C, and the solution was recovered for 30 minutes at each temperature to study the effect of temperature change on separation performance. After the test at 70°C, the solution was collected every 30 minutes and tested for 270 minutes to study the effect of aging.

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

Test Example 3-3. Result <Result 1>
Table 1 shows the results of an NF test performed on the film of Comparative Example 1 (γ-alumina) and the film of Example 1 (H-silica).

The film of Comparative Example 1 showed a low blocking rate of 13.6%, but the film coated with a silica layer showed a high blocking rate of 99.9% or more. Although the permeability coefficient is lower than the test performed only with the intermediate layer, when compared with the methyl orange separation test of the polymer membrane in the previous report shown in FIG. , it can be seen that the trade-off relationship is broken through.

<Result 2>
The results of the pervaporative separation test are shown in Table 2 (supply temperature 20°C). 6 and 7 show the effects of temperature and aging.

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

Claims (13)

A filtration membrane comprising a porous hydrophobic silica membrane and a support, wherein the porous hydrophobic silica membrane is disposed on the support, the support comprises a support layer and on the support layer The intermediate layer has a thickness of 0.2 to 5 μm, and the filtration membrane is a filtration membrane for filtering nano-sized solutes in a solution containing an organic solvent and solutes. , the nano-sized solute has a molecular weight of 200 to 1000,
The porous hydrophobic silica film is obtained by mixing an alkoxysilane containing a hydrophobic group linked to a silicon atom, a surfactant, and a solvent to hydrolyze and polymerize the alkoxysilane, and then calcining the resulting mixture. The resulting porous hydrophobic silica membrane,
The porous hydrophobic silica film is an alkoxysilane containing a silicon atom-linked hydrophobic group 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 are the same or different and represent an alkyl group having 1 to 4 carbon atoms]
is a polymer of
said filtration membrane; The filtration membrane of claim 1, wherein the nano-sized solute has a molecular weight of 200-500. 3. The filtration membrane of any one of claims 1 or 2, wherein the porous hydrophobic silica membrane has an average pore size of less than 2 nm. The filtration membrane according to any one of claims 1 to 3, wherein the porous hydrophobic silica membrane has an average pore size of 0.1 to 0.9 nm. The filtration membrane according to any one of claims 1 to 4, wherein the porous hydrophobic silica membrane has a thickness of 50 to 500 nm. The filtration membrane according to any one of claims 1 to 5, wherein the hydrophobic silica contains hydrocarbon groups. The filtration membrane according to claim 6, wherein the support has an average pore size of 2 to 500 nm. The filtration membrane according to claim 7, wherein the support layer has an average pore size of 20 to 500 nm, and the intermediate layer has an average pore size of 2 to 10 nm. The filtration membrane according to any one of claims 1 to 8, for use in filtration by pervaporation. A membrane module comprising the filtration membrane according to any one of claims 1 to 9. A membrane separation system comprising the membrane module according to claim 10 . A filtration method comprising filtering nano-sized solutes in a solution containing an organic solvent and solutes using the filtration membrane according to any one of claims 1 to 9. 13. The filtration method according to claim 12, wherein said filtration is performed by a pervaporation method.

Images