阅读说明：本技术 一种复合膜及其制备方法和应用 (Composite membrane and preparation method and application thereof ) 是由 张杨 刘轶群 潘国元 于浩 于 2019-04-01 设计创作，主要内容包括：本发明公开了一种复合膜及其制备方法以及该复合膜在水处理过程中的应用。所述复合膜包括支撑层、增强层和聚酰胺分离层,所述支撑层为聚合物多孔膜,所述支撑层的一个表面附着在增强层上,所述支撑层的另一个表面与聚酰胺分离层的一个表面贴合,所述聚酰胺分离层的另一个表面为含有胍基的表面改性层。本发明提供的复合膜,通过在聚酰胺膜表面接枝或者交联引入胍基,提高了膜的截盐率和抑菌性,有利于复合膜长时间运行而保持性能稳定。(The invention discloses a composite membrane, a preparation method thereof and application of the composite membrane in a water treatment process. The composite membrane comprises a supporting layer, a reinforcing layer and a polyamide separating layer, wherein the supporting layer is a polymer porous membrane, one surface of the supporting layer is attached to the reinforcing layer, the other surface of the supporting layer is attached to one surface of the polyamide separating layer, and the other surface of the polyamide separating layer is a surface modification layer containing guanidyl. According to the composite membrane provided by the invention, guanidino is introduced by grafting or crosslinking on the surface of the polyamide membrane, so that the salt rejection rate and the antibacterial activity of the membrane are improved, and the composite membrane can run for a long time and keep stable performance.)

1. The composite membrane is characterized by comprising a support layer, a reinforcing layer and a polyamide separation layer, wherein the support layer is a polymer porous membrane, one surface of the support layer is attached to the reinforcing layer, the other surface of the support layer is attached to one surface of the polyamide separation layer, and the other surface of the polyamide separation layer is a surface modification layer containing guanidyl.

2. The composite film of claim 1, wherein:

the polymer porous membrane of the support layer is one or more of polysulfone, polyethersulfone, sulfonated polyethersulfone, polytetrafluoroethylene, polyetherketone or polyacrylonitrile.

3. The composite film of claim 1, wherein:

the enhancement layer is one or more of a polyester layer, a polyethylene layer or a polypropylene layer.

4. The composite film of claim 1, wherein:

the polyamide separation layer is obtained by interfacial polymerization of polyamine and polybasic acyl chloride.

5. The composite film of claim 4, wherein:

the polyamine is selected from one or two of m-phenylenediamine, piperazine, polyethyleneimine or polyether amine; the polybasic acyl chloride is selected from one or more of trimesoyl chloride, isophthaloyl dichloride or terephthaloyl dichloride.

6. The composite film of claim 1, wherein:

the surface modification layer containing guanidine groups is obtained by surface modification of arginine and derivatives thereof on the surface of a polyamide separation layer.

7. The composite film of claim 6, wherein:

the arginine and its derivatives are selected from L-arginine, N ' - (4-methoxy-2, 3, 6-trimethylbenzenesulfonyl) -L-arginine, L-arginine-L-pyroglutamate, N ' -nitro-L-arginine, N ' -nitro-D-arginine, N-monomethyl-L-arginine monoacetate, D-arginine hydrochloride, N-benzoyl-L-arginine ethyl ester hydrochloride, N-alpha-carbonylphenoxy-D-arginine, L-arginine methyl ester dihydrochloride, N-fluorenylmethoxycarbonyl-L-arginine, N-benzyloxycarbonyl-L-arginine, N-p-toluenesulfonyl-L-arginine, L-arginine, One or more of NA-2, 4-dinitrobenzene-L-arginine and N-fluorenylmethyloxycarbonyl-D-arginine.

8. The composite film of claim 1, wherein:

the thickness of the surface modification layer containing guanidine groups is 0.002-0.05 mu m, and the preferable thickness is 0.005-0.03 mu m; the thickness of the supporting layer is 90-150 mu m, and preferably 100-120 mu m; the polyamide separation layer is 0.05-0.5 mu m in thickness, preferably 0.075-0.4 mu m in thickness, and the enhancement layer is 40-100 mu m in thickness, preferably 50-90 mu m in thickness.

9. A method of preparing a composite film according to any one of claims 1 to 8, characterized in that the method comprises the steps of:

(1) preparing a support layer on one surface of the reinforcing layer;

(2) forming a polyamide separation layer on the other surface of the support layer;

(3) and (3) modifying the surface of the polyamide separation layer obtained in the step (2) to obtain a surface modified layer containing guanidyl, and drying to obtain the surface modified composite membrane.

10. A method of preparing a composite membrane according to claim 9, characterized in that:

in the step (1), a supporting layer polymer solution is coated on one surface of the reinforcing layer, and the supporting layer with the surface attached with the reinforcing layer is obtained through phase inversion.

11. A method of preparing a composite membrane according to claim 9, wherein:

in the step (2), the other surface of the support layer is sequentially contacted with a solution containing polyamine and a solution containing polyacyl chloride, and then heat treatment is performed.

12. A method of making a composite membrane according to claim 11, wherein:

the mass concentration ratio of the polyamine to the polyacyl chloride is 1-100: 1, preferably 5 to 50: 1.

13. a method of making a composite membrane according to claim 11, wherein:

the conditions of the heat treatment are as follows: the temperature is 40-150 ℃ and the time is 0.5-20 min.

14. A method of preparing a composite membrane according to claim 9, wherein:

in the step (3), the polyamide separation layer obtained in the step (2) is contacted with a solution of arginine or a derivative thereof and a catalyst to modify the surface of the polyamide separation layer.

15. A method of making a composite membrane according to claim 14, wherein:

the catalyst is a pyridine compound, preferably one or more of pyridine, 2-methylpyridine or 4-dimethylaminopyridine.

16. A method of making a composite membrane according to claim 14, wherein:

in the solution of arginine or the derivative thereof, the content of arginine or the derivative thereof is 0.1 to 50 parts by weight, preferably 0.25 to 25 parts by weight, relative to 100 parts by weight of the solvent; the content of the catalyst is 0.001 to 5 parts by weight, preferably 0.005 to 2.5 parts by weight.

17. A method of preparing a composite membrane according to claim 9, wherein:

in the step (3), the drying conditions are as follows: the temperature is 20-100 ℃, and the time is 1-60 min.

18. Use of a composite membrane according to any one of claims 1 to 8 in a water treatment process.

Technical Field

The invention relates to the field of separation membranes, in particular to a composite membrane, a preparation method of the composite membrane and application of the composite membrane in a water treatment process.

Background

Nanofiltration and reverse osmosis are currently the most widely used water treatment technologies that rely on pressure drive to achieve separation. The pore diameter range of the nanofiltration membrane is about a few nanometers, the nanofiltration membrane has poor removal rate on monovalent ions and organic matters with the molecular weight less than 200, and has higher removal rate on divalent or multivalent ions and organic matters with the molecular weight between 200 and 500, so that the nanofiltration membrane can be widely applied to the fields of water softening, drinking water purification, water quality improvement, oil-water separation, wastewater treatment and recycling, seawater softening, grading, purification and concentration of chemical products such as dyes, antibiotics, polypeptides, polysaccharides and the like. Compared with a nanofiltration membrane, the reverse osmosis membrane has smaller aperture and good removal rate of monovalent ions, and is mainly applied to desalination of seawater and brackish water, preparation of boiler feed water, industrial pure water and electronic grade ultrapure water, production of drinking pure water, wastewater treatment and special separation processes.

Membrane materials are the core of membrane technology. Most of the separation layer materials of the commercial composite nanofiltration membranes and reverse osmosis membranes are aromatic polyamide. The aromatic polyamide has the advantages of high desalting rate, good water permeability, excellent chemical stability, low operation pressure and the like. However, none of the currently used composite membranes have antibacterial or bactericidal capabilities, which requires that the membranes be periodically sterilized and cleaned with a special chemical during actual operation. The use of biocides not only increases the cost of the film, but also causes the film to degrade, thereby reducing its useful life.

At present, in order to improve the biological pollution resistance of a nanofiltration membrane or a reverse osmosis membrane, antibacterial inorganic nanoparticles or high polymer materials with antibacterial performance are often introduced into a functional layer or the surface of the functional layer. Ag nanoparticles have broad-spectrum bactericidal performance, and a nano-silver modified nanofiltration membrane or a reverse osmosis membrane is reported in many documents and patents, so that the biological pollution resistance of the membrane is improved. CN101874989A (Timewton technologies, Inc.) discloses reverse osmosis which has been prepared by interfacial polymerizationAnd (3) penetrating the surface of the membrane, coating a layer of water phase containing nano silver and m-phenylenediamine, and crosslinking the surface of the membrane again to fix the silver nano particles on the surface of the membrane. Elimelch group of subjects dipped polyamide composite reverse osmosis membranes in AgNO-containing solution₃After draining, the solution is immersed in the aqueous solution containing NaBH₄In-situ reaction is utilized to generate nano silver on the surface of the membrane in the aqueous solution. CN 102527252A discloses a reverse osmosis membrane material with good antibacterial property, which is obtained by coating a layer of sericin macromolecule on the surface of a polyamide composite membrane and crosslinking. CN108057348A discloses that quaternary ammonium salt functional layer with bactericidal performance is grafted on the surface of polyamide separation layer by RAFT active polymerization method.

The guanidino has broad-spectrum bactericidal activity, has a bactericidal effect on gram-positive bacteria, gram-negative bacteria, fungi, yeasts and the like, and the safety of the guanidino is approved by the FDA and the EPA in the United states. Few patents and documents report that guanidino is introduced into a polyamide layer to improve the bacteriostatic activity of the composite membrane.

Disclosure of Invention

In order to overcome the problem that the existing composite membrane for water treatment has poor biological pollution resistance, the invention provides the composite membrane with excellent interception performance, good water permeability and excellent biological pollution resistance, a preparation method thereof and application of the composite membrane in the water treatment process.

The inventor of the invention finds that the arginine and the derivative thereof are branched and crosslinked to the surface of the polyamide, so that on one hand, the crosslinking density of the surface of the composite membrane is improved, and the salt rejection rate is improved; on the other hand, the introduction of guanidino groups improved the bacteriostatic activity of the composite membrane, thereby completing the present invention.

One of the purposes of the invention is to provide a composite membrane, which comprises a support layer, a reinforcing layer and a polyamide separation layer, wherein the support layer is a polymer porous membrane, one surface of the support layer is attached to the reinforcing layer, the other surface of the support layer is attached to one surface of the polyamide separation layer, and the other surface of the polyamide separation layer is a surface modification layer containing guanidyl.

According to the present invention, the support layer is not particularly limited, and may be made of various materials that have a certain strength and can be used for a reverse osmosis membrane or a nanofiltration membrane, and the polymer porous membrane of the support layer is preferably one or more membranes selected from polysulfone, polyethersulfone, sulfonated polyethersulfone, polytetrafluoroethylene, polyetherketone, and polyacrylonitrile, and more preferably a polysulfone porous support layer.

In the present invention, the source of the polymer porous membrane of the support layer is not particularly limited, and may be conventionally selected in the art, and for example, may be commercially available, and in a preferred case, may be self-prepared by a phase inversion method. The phase inversion method is well known to those skilled in the art, and may be, for example, a gas phase gel method, a solvent evaporation gel method, a thermal gel method, or an immersion gel method, and preferably an immersion gel method. In a preferred embodiment, a primary membrane is formed by coating a coating solution containing polysulfone on a reinforcing layer, and then the primary membrane is converted into a support layer using a phase inversion method to obtain a polysulfone porous support layer. The support layer may be a single pore or a porous structure.

In addition, in the invention, the thickness of the support layer can be changed within a larger range, and in order to achieve the purpose of better synergistic cooperation between the support layer and the polyamide separation layer and enable the obtained composite membrane to have better ion interception performance and higher water flux, the thickness of the support layer is preferably 90-150 μm, and more preferably 100-120 μm.

The reinforced layer is positioned on one surface of the supporting layer, so that the supporting layer is more favorably formed, and the composite film has better mechanical property. In addition, the reinforcing layer is not particularly limited in the present invention, and may be selected conventionally in the art, for example, one or more of a polyester layer, a polyethylene layer, or a polypropylene layer, preferably a polyester layer, and more preferably a polyester nonwoven fabric support layer. The source of the enhancement layer is not particularly limited and may be a conventional choice in the art, for example, commercially available.

The thickness of the reinforcing layer is not particularly limited, and may be conventionally selected in the art, and in a preferred case, the thickness of the reinforcing layer is 40 to 100 micrometers, and more preferably 50 to 90 micrometers.

The polyamide separating layer can be prepared by methods customary in the art, preferably by interfacial polymerization of polyamines with polyacyl chlorides.

In the present invention, the term "interfacial polymerization" means: polymerization reaction at the interface of two solutions (or the interface organic phase side) in which two monomers are dissolved, respectively, and which are not soluble in each other.

In the present invention, the type of the polyamine is not particularly limited, and may be an amine compound generally used in the art for producing a polyamide. Preferably, the polyamine is selected from one or two of m-phenylenediamine, piperazine, polyethyleneimine or polyether amine, and more preferably m-phenylenediamine.

In the interfacial polymerization, the polyamine is preferably used in the form of a solution, and the solvent for dissolving the polyamine may be a solvent which is incompatible with a solvent for dissolving a polybasic acid chloride described later and is inert to the polyamine. As such a solvent, for example, one or more of water, methanol, or acetonitrile; preferably water.

The concentration of the polyamine in the polyamine solution is not particularly limited and may be selected conventionally in the art. For example, the concentration of the polyamine in the polyamine solution may be 0.01 to 10% by weight, preferably 0.1 to 5% by weight, and more preferably 0.1 to 2.5% by weight.

In the present invention, the type of the polybasic acid chloride is not particularly limited, and may be any acid chloride compound commonly used in the art for producing polyamides. Preferably, the poly-acid chloride is selected from one or more of trimesoyl chloride, isophthaloyl chloride or terephthaloyl chloride, more preferably trimesoyl chloride.

In the interfacial polymerization, the polybasic acid chloride is preferably used in the form of a solution, and the solvent for dissolving the polybasic acid chloride may be a solvent which is incompatible with the solvent for dissolving the polyamine and inert to the polybasic acid chloride. Such a solvent may be, for example, an organic solvent, and the organic solvent is preferably one or more of n-hexane, dodecane, n-heptane, and paraffinic solvent oils (Isopar E, Isopar G, Isopar H, Isopar L, and Isopar M).

The concentration of the polybasic acid chloride in the polybasic acid chloride solution is not particularly limited and may be conventionally selected in the art. For example, the concentration of the polybasic acid chloride in the polybasic acid chloride solution may be 0.025 to 1 wt%, preferably 0.05 to 0.5 wt%.

In addition, in order to achieve the purpose of better synergistic cooperation between the support layer and the polyamide separation layer, the thickness of the polyamide separation layer is 0.05-0.5 μm, more preferably 0.075-0.4 μm, and further preferably 0.1-0.3 μm.

Preferably, the surface modification layer containing guanidine groups is obtained by surface modification of arginine and derivatives thereof on the surface of a polyamide separation layer.

In the present invention, the arginine and its derivatives are preferably L-arginine, N ' - (4-methoxy-2, 3, 6-trimethylbenzenesulfonyl) -L-arginine, L-arginine-L-pyroglutamate, N ' -nitro-L-arginine, N ' -nitro-D-arginine, N-monomethyl-L-arginine monoacetate, D-arginine hydrochloride, N-benzoyl-L-arginine ethyl ester hydrochloride, N-alpha-carbonylphenoxy-D-arginine, L-arginine methyl ester dihydrochloride, FMOC-L-arginine (N-fluorenylmethoxycarbonyl-L-arginine), N-benzyloxycarbonyl-L-arginine, N-phenyloxycarbonyl-L-arginine, one or more of N-p-toluenesulfonyl-L-arginine, NA-2, 4-dinitrobenzene-L-arginine, and FMOC-D-arginine (N-fluorenylmethyloxycarbonyl-D-arginine).

In the invention, in order to enable the obtained composite membrane to have better ion retention performance and higher water flux, the surface modified membrane with the guanidino-containing surface modified layer with the thickness of 0.002-0.05 μm is preferred, and the thickness of 0.005-0.03 μm is preferred.

Another object of the present invention is to provide a method for preparing the composite membrane, the method comprising the steps of:

(1) preparing a support layer on one surface of the reinforcing layer;

(2) forming a polyamide separation layer on the other surface of the support layer;

(3) and (3) modifying the surface of the polyamide separation layer obtained in the step (2) to obtain a surface modified layer containing guanidyl, and drying to obtain the surface modified composite membrane.

Wherein, the method of step (1) can be selected conventionally in the field, and preferably adopts a phase inversion method, and a supporting layer polymer solution can be coated on one surface of the reinforcing layer, and the supporting layer with the surface adhered with the reinforcing layer can be obtained through phase inversion.

The phase inversion method may specifically be: dissolving the polymer of the support layer in a solvent to obtain a polymer solution with the concentration of 10-20 wt%, and defoaming at 20-40 ℃ for 10-180 min; and then coating the polymer solution on the enhancement layer to obtain an initial membrane, and soaking the initial membrane in water at the temperature of 10-30 ℃ for 10-60 min, so that the polysulfone layer on the surface of the enhancement layer is subjected to phase conversion into the support layer polymer porous membrane.

Among them, the solvent may be N, N-dimethylformamide, N-dimethylacetamide, N-methylpyrrolidone, dimethylsulfoxide, or the like.

According to the method of the present invention, the composite membrane is obtained by forming a polyamide separation layer on one surface of the support layer in step (2). As a method for forming a polyamide separation layer on one surface of the support layer, it is preferable to obtain by interfacial polymerization of polyamine and polybasic acid chloride. The method for obtaining the polyamide separation layer by interfacial polymerization of the polyamine and the polybasic acid chloride is not particularly limited, and various conventional contact methods used in the art for interfacial polymerization of a polybasic acid chloride and a polybasic acid amine can be used. In the method of the present invention, preferably, the other surface of the support layer is contacted with the solution containing the polyamine and the solution containing the polybasic acid chloride in this order, followed by heat treatment.

The amount of the polyamine and the polybasic acyl chloride can be changed within a wide range as the conventional amount for interfacial polymerization in the field, and preferably, the mass concentration ratio of the polyamine to the polybasic acyl chloride is 1-100: 1, more preferably 5 to 50: 1.

according to the present invention, the conditions of the interfacial polymerization reaction are not particularly limited, and may be conventionally selected in the art, for example, in the case where the support layer is sequentially contacted with the solution containing the polyamine and the solution containing the polybasic acid chloride, the contact time of the support layer with the solution containing the polyamine is 5 to 100 seconds, preferably 10 to 60 seconds; the contact time of the supporting layer and the solution containing the polyacyl chloride is 5-100 s, preferably 10-60 s. The temperature during the contact may be 10 to 40 ℃.

In addition, when the heat treatment is performed, the conditions of the heat treatment include: the temperature is 40-150 ℃, and the time is 0.5-20 min; preferably, the conditions of the heat treatment include: the temperature is 50-120 ℃, and the time is 1-10 min.

In step (3) of the method according to the present invention, preferably, the polyamide separation layer obtained in step (2) is contacted with a solution of arginine or a derivative thereof and a catalyst, and an amino group in the arginine or the derivative thereof is reacted with an unreacted acid chloride on the surface of the polyamide, so that a guanidine group is attached to the surface of the polyamide, thereby modifying the surface of the polyamide separation layer of the composite membrane.

The method for contacting the composite membrane obtained in step (2) with arginine or a derivative thereof and a catalyst is not particularly limited, and various contact methods conventionally used in the art may be used. Preferably, the implementation process as the step (3) comprises: and (3) soaking the composite membrane obtained in the step (2) in a solution containing arginine or derivatives thereof and a catalyst, taking out and drying.

The time for immersing the composite membrane in the solution of arginine or the derivative thereof and the catalyst is not particularly limited, and preferably, the immersion time is 5 to 120 seconds, and more preferably, the immersion time is 10 to 60 seconds.

In addition, the drying conditions are not particularly limited, and preferably, the drying conditions include: the temperature is 20-100 ℃, and the time is 1-60 min; more preferably, the drying conditions include: the temperature is 25-80 ℃ and the time is 2-10 min. The adopted drying equipment adopts the drying equipment which is common in the prior art.

The catalyst is not particularly limited in the present invention, as long as it can promote the reaction of amino group and acyl chloride group, and is preferably a pyridine compound, more preferably one or a mixture of pyridine, 2-methylpyridine or 4-dimethylaminopyridine.

According to the method of the present invention, the content of arginine or a derivative thereof in the solution of arginine or a derivative thereof is 0.1 to 50 parts by weight, preferably 0.25 to 25 parts by weight, and more preferably 0.5 to 10 parts by weight, relative to 100 parts by weight of the solvent; the content of the catalyst is 0.001 to 5 parts by weight, preferably 0.005 to 2.5 parts by weight, and more preferably 0.01 to 1 part by weight.

According to the method of the present invention, the solvent dissolving arginine or a derivative thereof is water.

The invention also aims to provide the application of the composite membrane in the water treatment process.

In the invention, arginine and derivatives thereof are branched and crosslinked to the surface of polyamide, so that on one hand, the crosslinking density of the surface of the composite membrane is improved, and the salt rejection rate is improved; on the other hand, the introduction of guanidine groups improves the antibacterial activity of the composite membrane.

Detailed Description

The following describes in detail specific embodiments of the present invention. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.

In the following examples and comparative examples, the water flux and salt rejection of the composite membrane were tested by the following methods.

(1) Initial water flux of the composite membrane:

the composite membrane is put into a membrane pool, after the composite membrane is pre-pressed for 0.5h under 0.2MPa, the water permeability of the composite membrane within 1h is measured under the conditions that the pressure is 1.55MPa and the temperature is 25 ℃, and the water permeability is calculated by the following formula:

j is Q/(A.t), wherein J is water flux (L/m)²h) Q is water permeability (L), A is effective membrane area (m) of the composite membrane²) T is time (h);

(2) salt rejection of the composite membrane:

the composite membrane is put into a membrane pool, after the composite membrane is pre-pressed for 0.5h under 0.2MPa, the concentration change of the saline water solution with the initial concentration of 2000ppm and the salt in the permeate liquid within 1h is measured under the conditions that the pressure is 0.5MPa and the temperature is 25 ℃, and the composite membrane is obtained by the following formula:

R＝(C_P-C_f)/C_P× 100% where R is the salt rejection, C_PIs the concentration of salt in the stock solution, C_fIs the concentration of salt in the permeate; the salt may be MgSO₄NaCl or CaCl₂。

(3) The section appearance of the membrane is observed by a Hitachi S-4800 type high-resolution Field Emission Scanning Electron Microscope (FESEM), and the thickness of the membrane is obtained.

(4) Testing the bacteriostatic performance of the membrane: according to the guiding principle of microbial limit of the second part of Chinese pharmacopoeia 2010 edition, a certain bacterial liquid of CFU is fixed on a membrane sample to be tested by adopting a filtering method, the membrane sample is reversely attached to a proper culture medium, after 24 hours of culture, the membrane is taken down and printed to a disposable sterile filter membrane, the filter membrane is transferred to a culture plate according to a microbial limit measuring method for culture for 48 hours, and the antibacterial activity of the membrane is inspected by a microbial counting method.

In addition, in the following examples and comparative examples, L-arginine, N '- (4-methoxy-2, 3, 6-trimethylbenzenesulfonyl) -L-arginine, L-arginine-L-pyroglutamate, N' -nitro-L-arginine, N-monomethyl-L-arginine monoacetate, pyridine, 2-methylpyridine, 4-dimethylaminopyridine, trimesoyl chloride and m-phenylenediamine were purchased from Bailingwei science, Inc.; isopar E is available from Shilange chemical Co., Ltd; other chemicals were purchased from the national pharmaceutical group chemicals, ltd.

The preparation of the supporting layer on the surface of the reinforcing layer is prepared by adopting a phase inversion method, and the preparation method comprises the following specific steps:

dissolving a certain amount of polysulfone (the number average molecular weight is 80000) in N, N-dimethylformamide to prepare a polysulfone solution with the concentration of 18 weight percent, and defoaming at 25 ℃ for 120 min; then, the polysulfone solution was coated on a polyester nonwoven fabric (75 μm thick) with a doctor blade to obtain an initial film, which was then soaked in water at a temperature of 25 ℃ for 60min so that the polysulfone layer on the surface of the polyester nonwoven fabric was phase-converted into a porous film, and finally washed with water 3 times to obtain a polysulfone support layer.