JP2023108133A - Composite semipermeable film - Google Patents

Abstract

To provide a composite semipermeable film that is excellent in rate of blocking low-molecular organic solvents and further is excellent in water permeability, in processing water solutions containing the low-molecular organic solvents.SOLUTION: The semipermeable film comprises a porous support body having resistance to an organic solvent and a polyamide skin layer formed on a surface of the porous support body having resistance to an organic solvent.SELECTED DRAWING: Figure 1

Description

The present invention relates to composite semipermeable membranes.

Separation membranes are known that are configured with resistance to organic solvents taken into consideration. For example, Patent Document 1 describes a nanocomposite membrane in which a skin layer containing polyamide and silicone is formed on the surface of a porous support such as acrylonitrile. Patent Document 1 describes that the nanocomposite membrane is used for separating organic compounds having a molecular weight of 100 to 1000 dissolved in an organic solvent.

Patent Document 2 also describes a nanocomposite membrane in which a support made of an ethylenically unsaturated nitrile is provided with a hydrophilic coating. Patent Document 2 describes that the composite membrane can be used to separate sugars in an aqueous solution.

Japanese Patent Application Laid-Open No. 2003-320225 U.S. Pat. No. 6,113,794

Separation membranes such as those described in Patent Documents 1 and 2 can suppress phenomena such as swelling of the porous support, and can treat a liquid to be treated containing an organic solvent while maintaining good water permeability. It is possible to continue. However, the separation membranes of Patent Documents 1 and 2 are formed as nanocomposite membranes, and have a low rejection rate for low-molecular-weight organic solvents, and cannot substantially separate and concentrate organic solvents.

An object of one aspect of the present invention is to provide a composite semipermeable membrane that exhibits excellent rejection of low-molecular-weight organic solvents and excellent water permeability in the treatment of aqueous solutions containing low-molecular-weight organic solvents.

A composite semipermeable membrane according to one aspect of the present invention comprises an organic solvent-resistant porous support and a polyamide skin layer provided on the surface of the organic solvent-resistant porous support.

According to one aspect of the present invention, it is possible to provide a composite semipermeable membrane that exhibits excellent rejection of low-molecular-weight organic solvents and excellent water permeability in the treatment of aqueous solutions containing low-molecular-weight organic solvents.

1 shows a schematic cross-sectional view of a composite semipermeable membrane according to one embodiment of the present invention; FIG. 1 shows an example of a composite semipermeable membrane module according to one embodiment of the invention. 3 is an enlarged view of a portion of FIG. 2; FIG. 4 is an enlarged view of a portion of FIG. 3; FIG.

FIG. 1 shows an example of a composite semipermeable membrane according to one embodiment of the invention. As shown in FIG. 1, the composite semipermeable membrane 10 includes a porous support 2 and a skin layer (separation functional layer) 1 provided on the porous support (porous support layer) 2. . Moreover, as shown in FIG. 1, the composite semipermeable membrane 10 may include a substrate 3 for reinforcing the porous support 2 . As used herein, the term "semipermeable membrane" refers to a membrane that allows some of the components in the liquid to be treated to pass through, but does not allow the other components to pass through. Moreover, "composite" in the composite semipermeable membrane means that a plurality of layers having different functions or configurations are laminated.

The skin layer 1 is a dense thin layer (0.01 μm or more and 1 μm or less) arranged on the top of the composite semipermeable membrane 10, and is the layer where the separation treatment of the composite semipermeable membrane is mainly performed. The porous support plays a role of supporting the skin layer. The skin layer in this embodiment is a polyamide skin layer (the film forming method will be described later).

In this embodiment, an organic solvent-resistant porous support is used as the porous support. “Organic solvent resistance” means that even when the composite semipermeable membrane comes into contact with an organic solvent under normal conditions, it does not denature such as swelling or is difficult to denature, and the original function of the porous support is maintained. refers to Therefore, even when the composite semipermeable membrane according to the present embodiment is used for treating a liquid to be treated containing an organic solvent, the organic solvent does not swell the porous support or cause leak spots in the porous support. can be prevented, and continuous operation is possible while maintaining good separation performance.

The composite semipermeable membrane according to this embodiment, which is composed of an organic solvent-resistant porous support and a polyamide skin layer, is a separation membrane capable of concentrating the organic solvent contained in the liquid to be treated. That is, it has a structure capable of transmitting the solvent contained in the liquid to be treated but blocking the organic solvent. Here, the organic solvent to be concentrated may be a low-molecular-weight organic solvent, more specifically, an organic solvent having a molecular weight of 100 or less, preferably less than 100. Moreover, the above organic solvent is water-soluble, and may be dissolved in an arbitrary amount with a solubility in water of 0.1% or more. Furthermore, the liquid to be treated containing the above organic solvent may be an aqueous liquid, particularly an aqueous solution of an organic solvent. That is, the composite semipermeable membrane according to the present embodiment is suitably used for concentrating the low-molecular-weight organic solvent dissolved in the aqueous solution from the aqueous solution.

The organic solvent to be concentrated is preferably a low-molecular chain or alicyclic organic compound. Specific examples of organic solvents include acetonitrile, acetone, 1,4-dioxane, 1,3-dioxolane, cyclohexanone, gamma-butyllactone, tetrahydrofuran (THF), dimethylformamide (DMF), dimethylsulfoxide (DMSO), dimethylacetamide ( DMAc), N-methylpyrrolidone (NMP), γ-butyrolactone (GBL) and the like. Also, the organic solvent may be a water-soluble alcohol (including monohydric and polyhydric alcohols) having a molecular weight of 100 or less.

The organic solvent-resistant porous support in this embodiment mainly contains an organic solvent-resistant polymer (organic polymer or organic polymer compound), preferably composed of an organic solvent-resistant polymer. Specific examples of polymers used include polyetherimide, polyamideimide, polyimide, polyvinylidene fluoride, polyetherketone, polyetheretherketone, polyketone, polyethersulfone, polyallylethersulfone, and polyacrylonitrile. These polymers may be used alone or in combination of two or more, ie, as copolymers and/or polymer blends of two or more materials.

The composite semipermeable membrane provided with an organic solvent-resistant porous support according to this embodiment differs from a composite semipermeable membrane provided with a porous support formed using a material such as polysulfone, for example. Leak spots due to swelling or dissolution of the porous support can be prevented, and delamination between the porous support and the skin layer can be prevented. Therefore, even a liquid to be treated containing an organic solvent can be continuously treated with a good organic solvent rejection rate and permeation amount (water permeation amount).

Among the above-mentioned polymers used for the porous support layer, polyetherimide is preferred because of its excellent resistance to organic solvents. Polyetherimide is particularly excellent in resistance to ketones such as acetone, acetonitrile, and cyclohexanone, and also contributes to maintaining such organic solvent blocking performance. Therefore, by using polyetherimide for the porous support layer, the process of concentrating the organic solvent especially from the waste water containing the organic solvent such as ketone can be carried out over a long period of time. In addition, since polyetherimide has high flame retardancy, heat resistance, and compressive strength, it can maintain its strength even under high temperature and high pressure conditions of the composite semipermeable membrane. Sometimes heat and/or pressure damage to the membrane and other disadvantages can be prevented.

Specific examples of polyetherimide include the “Ultem (registered trademark)” series manufactured by SHPP US, and Ultem 1000 and the like can be preferably used. Moreover, the specific gravity of the polyetherimide used is about 1.2 to 1.3. The weight average molecular weight of the polyetherimide is preferably 5,000 or more and 500,000 or less, more preferably 10,000 or more and 50,000 or less. When the weight-average molecular weight is within the above range, it is possible to obtain appropriate workability and improve the strength of the porous support and, in turn, the composite semipermeable membrane.

The porous support may contain additives other than the organic solvent-resistant polymer described above as long as it does not interfere with the action and effect of the present embodiment. Examples of additives include functional particles such as colloidal silica and zeolite. Even in that case, the content of the organic solvent-resistant polymer is preferably 90% by mass or more, more preferably 95% by mass or more. The porous support preferably consists essentially of polyetherimide, more preferably polyetherimide. In the present specification, the phrase “consisting essentially of” a prescribed component means that it is permissible to contain a component other than the prescribed component, which is unavoidably generated or mixed during manufacturing.

The porous support is preferably a homogeneous layer as a whole. As used herein, a homogeneous layer means that the porous support is composed of a single phase, that is, no separate multiple phases are observed by ordinary observation methods in the art.

The average pore diameter on the surface of the porous support is preferably 5 nm or more and 50 nm or less, more preferably 7 nm or more and 20 nm or less. The above average pore size can improve the ability to block low-molecular-weight organic solvents, more specifically, organic solvents having a molecular weight of 100 or less.

The method for producing the porous support in this embodiment is not particularly limited, and non-solvent induced phase separation (NIPS), thermally induced solvent phase separation (TIPS), etc. can be used. It is preferable to use a non-solvent induced phase separation method (NIPS) because it can produce More specifically, after a polymer is dissolved in a solvent to obtain a membrane-forming solution, the membrane-forming solution is applied to a base material such as a nonwoven fabric using a die coater or the like. The polymer in the applied solution is then coagulated and the remaining solution is removed.

In the production of the porous support by the non-solvent-induced phase separation method, when the polymer is dissolved in the solvent, a uniform membrane-forming solution can be prepared and good phase separation can be obtained. and having a high boiling point are preferred. For example, the solvent used is preferably a water-soluble solvent having a boiling point of 130°C or higher and 250°C or lower. Specific examples of solvents include dimethylformamide (DMF), dimethylsulfoxide (DMSO), dimethylacetamide (DMAC), 1,3-dimethyl-2-imidazolidinone (DMI), N-methylpyrrolidone (NMP), γ- butyrolactone (GBL) and the like.

When producing a polymer solution for film formation of a porous support, in addition to the above solvents, polyoxyalkylenes such as polyethylene glycol and polybutylene glycol, water-soluble polymers such as polyvinyl alcohol and polyvinyl butyral, glycerin, and diethylene glycol are used. , water, acetone, 1,3-dioxolane and the like can be added as pore opening agents. By adding a predetermined amount of a pore-forming agent, the porosity, pore size, etc. of the porous support can be adjusted.

The composite semipermeable membrane according to this embodiment comprises a polyamide skin layer on the porous support. Such a skin layer covers the surface of the porous support formed on the substrate as described above, It can be formed by immersion in a solution of a polyfunctional amine compound. Thereafter, contacting with a solvent solution of the acid halide compound promotes interfacial polymerization between the polyfunctional amine and the acid halide compound, thereby forming a crosslinked polyamide.

Multifunctional amines (compounds having two or more reactive amine groups) can be aromatic multifunctional amines, aliphatic multifunctional amines, or combinations thereof. Specific examples of aromatic polyfunctional amines include m-phenylenediamine, p-phenylenediamine, 1,3,5-triaminobenzene, etc., or N-alkylated products thereof such as N,N-dimethyl m-phenylenediamine. , N,N-diethyl m-phenylenediamine, N,N-dimethyl p-phenylenediamine, N,N-diethyl p-phenylenediamine, among which m-phenylenediamine is preferred. Also, the aliphatic polyfunctional amine may be a chain or cycloaliphatic polyfunctional amine. Specific examples of aliphatic polyfunctional amines include ethylenediamine and ethylenediamine derivatives, chain diamines such as 1,6-diaminohexane, 1,3-diaminocyclohexane, 1,2-diaminocyclohexane, 1,4-diaminocyclohexane Cyclic diamines such as hexane, piperazine and piperazine derivatives are included. Examples of piperazine derivatives include 2,5-dimethylpiperazine, 2-methylpiperazine, 2,6-dimethylpiperazine, 2,3,5-trimethylpiperazine, 2,5-diethylpiperazine, 2,3,5-triethylpiperazine. , 2-n-propylpiperazine, 2,5-di-n-butylpiperazine, ethylenediamine and the like. Of the above, piperazine is preferred. The above polyfunctional amines can be used alone or in combination of two or more.

Note that when an aromatic polyfunctional amine such as m-phenylenediamine is used in forming the skin layer, a composite semipermeable membrane suitable for selectively separating monovalent salts can be obtained. can. Also, when an aliphatic polyfunctional amine such as piperazine is used, a composite semipermeable membrane suitable for selectively separating divalent salts can be obtained.

The acid halide compound is not particularly limited as long as it gives a polyamide by reaction with the polyfunctional amine, but an acid halide compound having two or more halogenated carbonyl groups in one molecule is preferable. Specific examples of acid halide compounds include oxalic acid, malonic acid, maleic acid, fumaric acid, glutaric acid, 1,3,5-cyclohexanetricarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, and the like. Fragrances such as halide compounds of fatty acids, phthalic acid, isophthalic acid, 1,3,5-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, 1,3-benzenedicarboxylic acid, 1,4-benzenedicarboxylic acid Acid halide compounds of group acids can be used. These acid halide compounds can be used alone or in combination of two or more.

The porous support is preferably covalently bonded to a skin layer provided on its surface. Here, when polyetherimide is used as the porous support, it is preferable that the polyetherimide is ring-opened and covalently bonded to the skin layer. Since covalent bonds are formed between the porous support and the skin layer, the porous support is less likely to deteriorate even when exposed to organic solvents, and delamination and leak spots are less likely to occur. Therefore, the organic solvent resistance of the composite semipermeable membrane is improved, and the separation performance of the composite semipermeable membrane, that is, the rejection rate and permeation amount of the organic solvent are improved.

A desired chemical bonding state between the porous support and the skin layer can be obtained by adjusting the concentration of the polyfunctional amine compound solution used to form the skin layer. For example, it is preferable to set the solution concentration of the polyfunctional amine compound to 0.5% by mass or more and 15% by mass or less. In addition, determination of the chemical bonding state between the porous support and the skin layer can be performed using, for example, an infrared spectroscopic analysis method, for example, using a Fourier transform infrared spectrophotometer (FT-IR). can be determined by measuring the peak intensity of the wavenumber of, for example, the intensity of the peak derived from the C=O stretching vibration of the imide group.

Furthermore, the composite semipermeable membrane according to this embodiment has a property of being resistant to deformation even when pressure is applied for a long period of time, that is, it has excellent pressure resistance. It can sufficiently cope with operation at a high operating pressure by the reverse osmosis method, for example, 1 to 20 MPa, particularly 2 MPa or higher, preferably 5 MPa or higher. More specifically, the compressibility of the portion of the composite semipermeable membrane consisting of the porous support and the skin layer, that is, the thickness reduced by being compressed by pressurization at a predetermined pressure for a predetermined time (initial thickness The ratio of the value obtained by subtracting the thickness after pressurization from the initial thickness is also small. For example, in the composite semipermeable membrane according to the present embodiment, the compressibility can be 20% or less, preferably 10% or less, more preferably 5% or less when the liquid to be treated is treated at an operating pressure of 5.5 MPa for 2 hours. .

The porosity (porosity) of the porous support before use of the composite semipermeable membrane is preferably 40% or more and 70% or less, more preferably 55% or more and 65% or less. By having the porosity in the above range, it is possible to obtain appropriate organic solvent blocking performance and water permeability when treating an aqueous organic solvent solution, and to improve the pressure resistance and strength of the composite semipermeable membrane. Furthermore, even when the composite semipermeable membrane is compressed and reduced in thickness by applying pressure for a long time or high pressure, high permeation performance can be maintained.

As the base material for the composite semipermeable membrane, a fiber planar structure, specifically, a woven fabric, a knitted fabric, a nonwoven fabric, or the like can be used. Among these, nonwoven fabrics are preferred. Nonwoven fabrics are produced by spunbonding, spunlacing, meltblowing, carding, air laying, wet, chemical bonding, thermal bonding, needle punching, water jet, stitch bonding, electrospinning, etc. It may have been Moreover, although the kind of fiber which comprises a nonwoven fabric is not limited, it is preferable that it is a synthetic fiber. Specific examples of fibers include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), polypropylene (PP), polyethylene (PE), and polyphenylene sulfide (PPS). , polyvinylidene fluoride (PVDF), polyglycolic acid (PGA), polylactic acid (PLA), nylon 6, polycaprolactone (PCL), polyethylene adipate (PEA), polyhydroxyalkanoate (PHA), or copolymers thereof you can Among these, it is preferable to use polyester such as polyethylene terephthalate because it is inexpensive, has high dimensional stability and moldability, and has high oil resistance.

The total thickness of the composite semipermeable membrane 10 may be 60 μm or more and 250 μm or less. The thickness of the porous support can be 10 μm or more and 100 μm or less. The thickness of the skin layer can be 0.01 μm or more and 1 μm or less. Moreover, the thickness of the base material can be 50 μm or more and 200 μm or less.

According to the composite semipermeable membrane of this embodiment, a permeation amount of 1 LMH or more, preferably 5 LMH or more can be obtained. Also, an organic solvent rejection rate of 50% or more, preferably 60% or more can be achieved. By blocking the organic solvent at 50% or more, the organic solvent can be concentrated.

Furthermore, the composite semipermeable membrane according to this embodiment is suitably used as a reverse osmosis membrane or a nanofiltration membrane, particularly as a reverse osmosis membrane. Therefore, the composite semipermeable membrane according to the present embodiment can concentrate an organic solvent and desalt with a high salt rejection rate.

The composite semipermeable membrane according to this embodiment is preferably configured in a flat membrane shape. In addition, the flat membrane-shaped composite semipermeable membrane according to the present embodiment can be used in a spiral membrane module configured by winding the composite semipermeable membrane spirally around the outside of a water collection tube. It can be used in a disk tube type composite semipermeable membrane module in which a plurality of (plate-like) composite semipermeable membranes are stacked and arranged, particularly in a disk tube type reverse osmosis (DTRO) module.

FIG. 2 shows a cross-sectional view of an example of a disk tube type reverse osmosis membrane module. Also, FIG. 3 shows an enlarged view of the portion A of FIG. Further, FIG. 4 shows an enlarged view of portion B of FIG. As shown in FIG. 2, the disc tube membrane module 100 includes a disc tube reverse osmosis membrane (also referred to as a membrane cushion) 15 for a disc tube reverse osmosis membrane, which is configured using the composite semipermeable membrane 10 described above. , are arranged in multiple stages in a tubular casing.

As shown in FIGS. 3 and 4, the disc-shaped reverse osmosis membrane (membrane cushion) 15 is formed by stacking a pair of composite semipermeable membranes 10, 10 so that the substrates 3 face each other. It has a configuration in which the periphery is closed, for example, by heat sealing or the like. In the illustrated example, a permeate spacer 8 is arranged between the pair of composite semipermeable membranes 10 , 10 of the membrane cushion 15 . The disc-shaped reverse osmosis membrane 15 is configured such that water to be treated enters from the surfaces (skin layers 1) of the pair of composite semipermeable membranes 10, 10 and flows between the composite semipermeable membranes 10, 10. FIG. In FIG. 3, arrows indicate the flow of the water to be treated Wf, the concentrated water Wc, and the permeated water Wp.

A casing of the disc tube membrane module 100 is composed of end face portions 31 and 32 closing upper and lower end faces of a tubular peripheral wall portion 30 . In the example of FIG. 2, the end surface portion 31 has an inlet for introducing the water to be treated Wf inside, and an outlet for draining the liquid (concentrated water Wc) that has not passed through the disk-shaped reverse osmosis membrane 15. , and an outlet port for draining the liquid (permeated water Wp) that has permeated the disc-shaped reverse osmosis membrane 15 . A hole is formed in the central portion of the disk-shaped reverse osmosis membrane 15, and by inserting the shaft 35 into this hole, the plurality of disk-shaped reverse osmosis membranes 15 are stably arranged in the casing.

A spacer disk 20 is arranged between the disk-shaped reverse osmosis membranes 15 , 15 . Due to the presence of the spacer discs 20 , channels can be formed between the disc-shaped reverse osmosis membranes 15 as well. In other words, the disc-shaped reverse osmosis membrane 15 is sandwiched between spacer discs 20,20. The disc-shaped reverse osmosis membrane 15 is tightly sealed near the shaft 35 by a packing 34 or the like to separate the feed side (the concentrated water Wc side) and the permeate side (the permeated water Wp side).

As shown in FIG. 2, the water to be treated (supply water) Wf is introduced through between the inner peripheral surface of the peripheral wall portion 30 and the outer peripheral surface of the spacer disk 20, and further reaches the surface of the disk-shaped reverse osmosis membrane 15. flow along. The liquid that has not permeated through the disk-shaped reverse osmosis membrane 15 flows repeatedly from the side of the peripheral wall 30 to the side of the shaft 35, and from the side of the shaft 35 to the side of the peripheral wall 30. It is guided from. On the other hand, the liquid that permeates the disk-shaped reverse osmosis membrane 15 flows in the direction of the axis 35 inside the disk-shaped reverse osmosis membrane 15, and along the flow path between the inner peripheral surface of the center of the spacer disk 20 and the axis 35 It is discharged from the outlet for the permeated water Wp.

Although not shown, a large number of projections may be formed on both main surfaces of the spacer disk 20, and the disk-shaped reverse osmosis membrane 15 can be held by these projections. Moreover, the water to be treated flowing along the disk-shaped reverse osmosis membrane 15 collides with the projections of the spacer disk 20 to generate turbulent or irregular flow. Such flow turbulence makes it difficult for impurities to stay on the surface of the disk-shaped reverse osmosis membrane 15, suppresses clogging of the membrane, and improves the recovery rate. When a disk tube type membrane module is used, an organic solvent recovery rate of 75% or more, preferably 90% or more can be achieved.

In addition, the disc tube membrane module 100 can be used at a high operating pressure, for example, up to 20 MPa, by using a pressure-resistant casing as the casing.

As described above, the disk tube type reverse osmosis membrane module is often used under high pressure and also at high temperature. It is preferably used. In addition, in the case of a membrane with a porous support containing polyetherimide, the effects of heat can be suppressed when fabricating the membrane cushion (for example, when heat-sealing the edges), and the module can be assembled. The possibility of ignition due to welding between the permeable membrane cushion and the permeated water spacer can be reduced, and safety is high.

Therefore, one embodiment of the present invention may be a disc tube type membrane module in which composite semipermeable membranes are arranged in multiple stages, preferably a disc tube type reverse osmosis membrane module in which reverse osmosis membranes are arranged in multiple stages. . Further, one embodiment may be a wastewater treatment system including one or more disc tube type reverse osmosis membrane modules in which reverse osmosis membranes are arranged in multiple stages.

Furthermore, in one embodiment of the present invention, an aqueous liquid to be treated containing a water-soluble organic solvent having a molecular weight of 100 or less is treated using the composite semipermeable membrane or disc tube membrane module described above, and the water-soluble organic solvent is concentrated. It may be a method for treating a water-based liquid to be treated.

The composite semipermeable membrane and disc tube membrane module according to this embodiment are particularly suitable for treating aqueous liquids containing organic solvents. For example, organic solvents can be recovered from wastewater containing organic solvents used in semiconductor manufacturing plants, such as photoresist cleaning agents and degreasing agents used in degreasing processes. In addition, wastewater from petroleum refining plants, petrochemical plants, thermal power plants, automobile manufacturing plants, oil manufacturing plants, food manufacturing plants, etc., seawater containing organic solvents, or liquids obtained by pretreatment of these It can be suitably used to recover organic solvents and to purify and purify water. The concentrated water obtained through the membrane module may be distilled in a distillation column or the like to separate the distilled water and further concentrate the organic solvent.

Hereinafter, embodiments of the present invention will be described based on experimental examples. Example 1 is an example and Example 2 is a comparative example.

(Example 1)
19 parts by weight of polyetherimide (“Ultem 1000” manufactured by SHPP US) and 81 parts by weight of N,N-dimethylformamide were dissolved by heating at 50° C. to obtain a uniform film-forming solution. After cooling to room temperature, the film forming solution was impregnated and applied to a polyester nonwoven fabric substrate having a thickness of 0.1 mm and a density of 0.7 g/cm ³ using a film forming apparatus adjusted to a coater gap of 150 µm. A polyetherimide porous support was formed by immersing in a coagulation bath at 40° C. to coagulate, and washing and removing the residual solvent in a water washing bath at 70° C.

A 2 mass % aqueous solution of m-phenylenediamine was brought into contact with the surface of the formed polyetherimide porous support, and then excess m-phenylenediamine aqueous solution was removed. Subsequently, it was brought into contact with a naphthene solution containing 0.1% by mass of trimesic acid trichloride (aromatic acid halide compound) and 0.13% by mass of isophthaloyl chloride. After that, it was dried in a dryer at 140°C. As a result, a composite semipermeable membrane was obtained in which the nonwoven fabric, the porous support, and the polyamide skin layer were arranged in this order.

(Example 2)
As the membrane of Example 2, a composite semipermeable membrane used for RS50 (manufactured by Nitto Denko Corporation), which is a spiral UF membrane element, was prepared. The composite semipermeable membrane is a membrane in which a polyvinylidene fluoride (PVDF) porous support is formed on a base material of nonwoven fabric, and does not have a skin layer.

<Performance evaluation>
The obtained composite semipermeable membrane was placed in a membrane evaluation apparatus (flow type flat membrane test cell manufactured by Nitto Denko Corporation, Membrane Master C70-F, effective permeation area: 32.5 cm ² ), and an aqueous solution of an organic solvent was added. It was supplied as a liquid to be treated. The cross-flow system was operated for 1 hour at a supply flow rate of 5 L/min. The treatment pressure was 5.8 MPa for Example 1 and 0.05 MPa for Example 2. A 7.6% aqueous solution of cyclohexanone (molecular weight: 98.15) was used as the liquid to be treated. The concentration of cyclohexanone was measured on the feed side and the permeate side, and the rejection rate (%) of the organic solvent was calculated. Rejection rate (%)=[1-{(concentration of organic solvent in permeated water)/(concentration of organic solvent in raw water)}]×100. The concentration of cyclohexanone was measured based on the Brix value using a refractometer (manufactured by Atago Co., Ltd., digital refractometer RX-5000α). In addition, the amount of water permeation was also measured. Table 1 shows the results.

From Table 1, in Example 1 using a composite semipermeable membrane having a polyetherimide porous support and a polyamide skin layer provided on its surface, a low molecular weight water-soluble organic solvent can be blocked with a high rejection rate. , also showed high permeability.

REFERENCE SIGNS LIST 1 skin layer 2 porous support 3 substrate 8 permeate spacer 10 composite semipermeable membrane 15 membrane cushion 20 spacer disk 30 peripheral wall 31, 32 end surface 35 shaft 100 disc tube membrane module

Claims (6)

A composite semipermeable membrane comprising an organic solvent-resistant porous support and a polyamide skin layer provided on the surface of the organic solvent-resistant porous support. The organic solvent-resistant porous support is a group consisting of polyetherimide, polyamideimide, polyimide, polyvinylidene fluoride, polyetherketone, polyetheretherketone, polyketone, polyethersulfone, polyallylethersulfone, and polyacrylonitrile. The composite semipermeable membrane according to claim 1, comprising one or more selected from The composite semipermeable membrane according to claim 1 or 2, capable of concentrating a water-soluble organic solvent having a molecular weight of 100 or less. The organic solvent is acetonitrile, acetone, 1,3-dioxane, 1,4-dioxolane, cyclohexanone, gamma-butyllactone, tetrahydrofuran (THF), dimethylformamide (DMF), dimethylsulfoxide (DMSO), dimethylacetamide (DMAc), The composite semipermeable membrane according to claim 3, which is one or more selected from the group consisting of N-methylpyrrolidone (NMP), γ-butyrolactone (GBL), and alcohol. 5. The organic solvent resistant porous support according to any one of claims 1 to 4, wherein the organic solvent resistant porous support is a polyetherimide, and the polyetherimide is ring-opened and covalently bonded to the polyamide skin layer. Composite semipermeable membrane. A disk-tube membrane module, wherein the composite semipermeable membrane according to any one of claims 1 to 5 is configured in a flat plate shape, and the composite semipermeable membranes are arranged in multiple stages.

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