Preparation method and application of anti-pollution polyamide composite membrane

Abstract

The application discloses a preparation method and application of an anti-pollution polyamide composite membrane. The preparation method comprises the following steps: 1) generating polyamide on the surface of a porous carrier through an interfacial polymerization reaction of a polyamine and a multifunctional acyl chloride, and preparing a modified polyamide layer by the following method; mixing a monomer containing at least one carboxyl group and one amino group with the polyamine or the multifunctional acyl chloride before the interfacial polymerization to obtain the modified polyamide layer; or coating the monomer containing at least one carboxyl group and one amino group on the surface of the polyamide after the interfacial polymerization to obtain the modified polyamide layer; 2) coating a mixture containing a photoinitiator, a crosslinking agent, an unsaturated acid or an ester monomer on the modified polyamide layer to form a coating layer; and 3) performing light irradiation treatment on the coating layer to initiate a crosslinking polymerization reaction, so that the anti-pollution polyamide composite membrane is prepared. The polyamide composite membrane prepared by the method has strengthened anti-pollution performance and can be applied to the field of water treatment as an anti-pollution reverse osmosis membrane.

Description

Technical Field

[0001] This invention relates to a polyamide composite film, and more particularly to a method for preparing and applying an antifouling polyamide composite film. Background Technology

[0002] Since John Cadotte successfully prepared reverse osmosis membranes through interfacial polymerization in the 1970s, this technology has been widely used in water treatment industries such as drinking water, food and beverage, medical and pharmaceutical, municipal water supply treatment, industrial high-purity water, and seawater desalination due to its separation characteristics such as high efficiency, low energy consumption, and high selectivity. After decades of continuous optimization of the reaction process and reaction additives by researchers, the performance of reverse osmosis membranes, such as membrane flux and salt rejection rate, has been greatly improved compared to decades ago.

[0003] However, the problem of reverse osmosis membrane fouling is becoming increasingly prominent. Membrane fouling leads to a significant decrease in membrane flux, increases the frequency of cleaning, raises operating costs, and also reduces the desalination performance of membrane elements. Therefore, developing antifouling reverse osmosis membranes is currently a top priority in the development of reverse osmosis membrane technology. Research has found that the hydrophobicity and peak-valley structure of aromatic polyamide membrane surfaces are the main causes of severe membrane fouling. Currently, the development of antifouling reverse osmosis membranes mainly falls into two categories: composite coatings (e.g., US6177011, CN105833743) and membrane surface modification (e.g., CN104785131, CN104815567, CN106669439). These methods all face drawbacks such as high equipment requirements, increased costs, and complex operation. Therefore, there is still considerable room for improvement in the development of existing antifouling reverse osmosis membrane technologies. Summary of the Invention

[0004] To address the above technical problems, this invention proposes a method for preparing and applying an anti-fouling polyamide composite membrane.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A method for preparing an antifouling polyamide composite film includes the following steps:

[0007] 1) Polyamide is generated by interfacial polymerization of polyamine and polyfunctional acyl chloride on the surface of a porous support, and the modified polyamide layer is prepared by the following method;

[0008] Before interfacial polymerization, a monomer containing at least one carboxyl group and one amino group is mixed with a polyamine to obtain a modified polyamide layer; or,

[0009] After interfacial polymerization, a monomer containing at least one carboxyl group and one amino group is coated onto the surface of the polyamide to obtain a modified polyamide layer;

[0010] 2) A mixture containing a photoinitiator, crosslinking agent, unsaturated acid or ester monomer is coated onto the modified polyamide layer to form a coating layer;

[0011] 3) The coating layer is subjected to light treatment to initiate a cross-linking polymerization reaction, thereby obtaining an anti-fouling polyamide composite film.

[0012] As a preferred embodiment of the invention, the porous carrier may be a polysulfone-based membrane, polyethersulfone, polyphenylsulfone, polyphenylene sulfide, polyphenylene sulfide, polyphenylene sulfide, polyamide, polyimide, polyester, vinyl polymer, cellulose polymer, etc., formed on a nonwoven fabric, wherein the vinyl polymer is selected from polyethylene, polypropylene, polyvinyl chloride, polyacrylonitrile, etc., and the cellulose polymer is selected from cellulose acetate, cellulose nitrate, etc.

[0013] As a preferred embodiment of the invention, the polyamine is selected from one or more of m-phenylenediamine, p-phenylenediamine, piperazine, aliphatic amines, and polyetheramines; wherein the aliphatic amine may be selected from one or more of ethylenediamine, pentanediamine, and hexamethylenediamine.

[0014] The polyfunctional acyl chloride is selected from aromatic or alicyclic polyfunctional acyl chlorides, preferably one or more of the following: pyromellitic tricarboxylic acid chloride, terephthaloyl chloride, isophthaloyl chloride, biphenyl dicarboxylic acid chloride, naphthalene dicarboxylic acid chloride, cyclopropane tricarboxylic acid chloride, cyclobutane tetracarboxylic acid chloride, cyclopentane tricarboxylic acid chloride, cyclopentane tetracarboxylic acid chloride, cyclohexane tricarboxylic acid chloride, cyclopentane dicarboxylic acid chloride, cyclobutane dicarboxylic acid chloride, cyclohexane dicarboxylic acid chloride, and tetrahydrofuran dicarboxylic acid chloride.

[0015] As a preferred embodiment of the invention, the polyamine is prepared into a polar solution of 0.1-20 wt%, preferably 2-5 wt%, before interfacial polymerization, and the polyfunctional acyl chloride is prepared into a non-polar solution of 0.01-5 wt%, preferably 0.05-3 wt%, before interfacial polymerization. The two are subjected to interfacial polymerization by coating them separately onto a porous support or by immersing the porous support separately in the polar solution and the non-polar solution.

[0016] The polar solution may be methanol or water, and water is preferred as the polar solution considering both cost and safety.

[0017] The nonpolar solution is preferably a hydrocarbon solvent. Non-limiting examples of suitable hydrocarbon solvents include any one or a combination of at least two of the following: alkanes (n-hexane, octane, nonane, decane), isoalkanes (Isopar E, Isopar G, Isopar L), aromatics (mesotriene, m-xylene, toluene), etc., more preferably n-decane and Isopar L.

[0018] As a preferred embodiment of the invention, the interfacial polymerization reaction temperature is 10-40℃, preferably 20-30℃, and the reaction time is 0.5-5 minutes, preferably 0.5-2 minutes. After the polymerization reaction, excess liquid can be removed by any of the following methods: air knife, drying, dropleting, or baking.

[0019] As a preferred embodiment of the invention, in step 1), the monomer containing at least one carboxyl group and one amino group is selected from one or more of carboxymethyl chitosan, hyaluronic acid, aspartic acid, glutamic acid, serine, threonine, and cysteine.

[0020] As a preferred embodiment of the invention, in step 1), if a monomer containing at least one carboxyl group and one amino group is mixed with a polyamine before interfacial polymerization, the mass concentration ratio of the two is (0.1-2):1, preferably (0.2-0.5):1.

[0021] If a monomer containing at least one carboxyl group and one amino group is coated onto the surface of the polyamide after interfacial polymerization, the mass concentration of the monomer containing at least one carboxyl group and one amino group is 0.5-2 wt%. Preferably, the surface temperature of the polyamide is 10-40°C, more preferably 20-30°C, during coating, so that the amino group in the monomer reacts further with the residual acyl chloride group in the polyamide to obtain a cross-linked structure.

[0022] From the perspective of easier solubility and reaction, the monomer containing at least one carboxyl group and one amino group is preferably mixed with the polyamine in a polar solution to participate in the interfacial polymerization reaction.

[0023] As a preferred embodiment of the invention, the photoinitiator is preferably a visible light initiator, which may be selected from one or more of isopropylthioxanthone (ITX), camphorquinone (CQ), diphenyltitane fluoride, and bis(pentafluorophenyl)titane; considering water solubility and cost, camphorquinone (CQ) is preferred as a visible light photoinitiator.

[0024] Preferably, the crosslinking agent is N,N'-methylenebisacrylamide;

[0025] Preferably, the unsaturated acid or ester monomer is selected from acrylic acid and acrylate, and more preferably one or more of acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, methyl 2-methacrylate, and ethyl 2-methacrylate. From the perspective of water solubility, acrylic acid is preferred.

[0026] As a preferred embodiment of the invention, in step 2), the mass concentration of the photoinitiator in the mixture is 0.1-0.5 wt%, the mass concentration of the crosslinking agent is 0.05-0.2 wt%, the mass concentration of the unsaturated acid or ester monomer is 0.1-0.5 wt%, and the solvent used is one or more of water, methanol, ethanol, and isopropanol.

[0027] As a preferred embodiment of the invention, the light treatment conditions in step 3) can be selected according to the type of photoinitiator. When the photoinitiator is a visible light initiator, visible light with a wavelength of 390-780nm is used for irradiation, preferably visible light with a wavelength of 440-500nm; the light temperature is 10-80℃, preferably 35-60℃, and the light time is 0.5-30min, preferably 1-10min.

[0028] To promote the interfacial polymerization reaction and regulate the reaction rate and composite membrane properties, one or more of the following additives may be optionally added to the interfacial polymerization reaction: a phase transfer catalyst (e.g., dodecyltrimethylammonium chloride), an acid-binding agent (e.g., sodium hydroxide, camphor sulfonic acid, triethylamine and its salts), a solubilizer (e.g., toluene), a complexing agent (e.g., phosphate esters), and a humectant (e.g., glycerin). The amount of each additive can be referred to any known technique, and will not be elaborated here.

[0029] The present invention also provides an application of the antifouling polyamide composite membrane prepared by the method described above in the field of reverse osmosis water treatment.

[0030] This invention modifies polyamides using monomers containing at least one carboxyl group and one amino group. The amino group in the monomer reacts with acyl chlorides to form a polyamide structure, which alters the flatness of the polyamide membrane and improves its antifouling performance. Simultaneously, the remaining carboxyl group in the molecule can polymerize with unsaturated acid or ester monomers in the presence of a crosslinking agent to obtain a robust, smooth, hydrophilic coating. This effectively reduces membrane surface roughness, improves hydrophilicity and scratch resistance, and through optimized adjustment and synergistic effects of the components, significantly enhances the antifouling performance of the composite membrane without compromising its separation performance. This allows for wide applications in reverse osmosis water treatment. The improved antifouling performance significantly reduces the frequency of reverse osmosis membrane cleaning, minimizes damage to the membrane element surface from chemical cleaning solutions, and effectively extends the service life of the reverse osmosis membrane. Attached Figure Description

[0031] Figure 1 Surface electron microscope (left) and cross-sectional electron microscope (right) of the polyamide composite film prepared in Example 1.

[0032] Figure 2 Surface electron microscopy (left) and cross-sectional electron microscopy (right) of the polyamide composite film prepared for Comparative Example 1.

[0033] Figure 3 Surface electron microscopy (left) and cross-sectional electron microscopy (right) of the polyamide composite film prepared for Comparative Example 2. Detailed Implementation

[0034] The present invention will be further illustrated below with specific embodiments. These embodiments are merely illustrative and do not limit the scope of the invention.

[0035] I. Sources and brands of main reagents in the examples and comparative examples:

[0036] Polysulfone, purchased from BASF, Germany, Ultrason S6010.

[0037] Non-woven fabric, purchased from Zhejiang Qinglan Membrane Technology Co., Ltd., R80.

[0038] Polysulfone-based membrane preparation method: Polysulfone is dissolved in N,N-dimethylformamide to prepare a solution with a solid content of 18%. The polysulfone solution is coated onto the surface of nonwoven fabric using a wet membrane preparation device with a thickness of 250 micrometers. After being left in the air for 4-5 seconds, the nonwoven fabric is immersed in room temperature pure water. After immersion for 5 minutes, the phase inversion is completed. The polysulfone-based membrane that has completed the phase inversion is then immersed in room temperature pure water. The water is changed every 2 hours to thoroughly clean the residual solvent. After that, it is cut for use.

[0039] Unless otherwise specified, all other reagents were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., and are reagent-grade raw materials.

[0040] II. Test methods for composite membrane performance in the examples and comparative examples:

[0041] Desalination rate and flux testing methods: Refer to the desalination rate and flux testing methods in GB / T32373-2015 "Reverse Osmosis Membrane Test Methods". The test solution temperature is 25℃, the pH value is 7.0, the test solution is 2000ppm sodium chloride aqueous solution, the test pressure is 1.55MPa, and the membrane is operated for 24 hours. By measuring the water quality of the permeate and the supply water before and after the membrane, the various membrane performance parameters are determined.

[0042] Desalination rate calculation method:

[0043] Desalination rate (%) = 100 × {1 - (salinity of permeate water / salinity of supply water)}.

[0044] Flux calculation method:

[0045] The membrane permeate flow rate of the supplied water (seawater) is converted into the permeate flow rate (cubic decimeters) per square meter of membrane area per hour, expressed as membrane permeate flux (L / m²). 2 / h) indicates.

[0046] Anti-fouling performance test:

[0047] Pollution test conditions: The test solution temperature was 25℃, the pH value was 7.0, and the test solution was an aqueous solution containing 2000 ppm sodium chloride and 10 ppm bovine serum albumin. The test pressure was 1.55 MPa, the influent flow rate was 3 L / min, and the composite membrane was immersed in the flowing test solution to observe the performance changes over time.

[0048] Chemical cleaning test conditions: Chemical cleaning is performed to remove contaminants from the contaminated composite membrane. A sodium hydroxide solution (pH=12.5) is circulated within the equipment for 30 minutes instead of an aqueous sodium chloride solution, followed by static soaking for 60 minutes and circulation for another 30 minutes. The sodium hydroxide solution is then drained, and the equipment is rinsed with pure water for 15-30 minutes. A citric acid / hydrochloric acid mixture (pH=1.5) is then used instead of pure water, and the equipment is run for 30 minutes, followed by static soaking for 60 minutes and circulation for 30 minutes. The citric acid / hydrochloric acid mixture is drained from the equipment, and rinsing with pure water continues for 15-30 minutes. Finally, a 2000 ppm sodium chloride solution is used at 25°C and 1.55 MPa for 60 minutes to test the composite membrane flux and desalination rate.

[0049] Long-term test (30 cycles): The membrane was subjected to a multi-cycle fouling-chemical cleaning test under the above test conditions. The changes in membrane performance over time after fouling were recorded at the 30th cycle. At the same time, the changes in membrane performance over time after chemical cleaning in the 30th cycle were also measured.

[0050]

Example 1

[0051] At 25°C, the cut polysulfone-based membrane is attached to a rectangular frame with sides of 16*12cm. The frame is then immersed in an aqueous solution containing 3.5wt% m-phenylenediamine, 1wt% carboxymethyl chitosan, 6wt% camphor sulfonic acid, and 3wt% triethylamine for 1 minute. Excess aqueous phase is removed by squeezing with a rubber roller. Then, an organic phase containing 0.165wt% pyromellitic acid chloride and n-decane is poured onto the surface of the polysulfone-based membrane and reacted for 1 minute, with the membrane surface temperature controlled at 25°C. Excess solution on the membrane surface is then removed with an air knife, and the membrane is washed in 90°C hot water for 2 minutes to obtain a composite membrane containing a modified polyamide layer. An aqueous solution containing 0.05 wt% N,N'-methylenebisacrylamide, 0.2 wt% camphorquinone, and 0.1 wt% acrylic acid was poured onto the surface of the composite film, followed by irradiation under visible light at 60°C for 2 minutes to obtain a polyamide composite film. The surface electron microscope (left) and cross-sectional electron microscope (right) images are shown below. Figure 1 As shown. From Figure 1 It can be seen that the polyamide blades on the surface of the membrane are large and closely spaced under electron microscopy, and there are no obvious protrusions in the cross-sectional electron microscopy, indicating that the surface has good flatness.

[0052] Comparative Example 1

[0053] The polyamide composite film was prepared using essentially the same method as in Example 1, except that carboxymethyl chitosan was not added during the preparation process. The surface electron microscope (left) and cross-sectional electron microscope (right) images of the resulting polyamide composite film are shown below. Figure 2 As shown. From Figure 2 It can be seen that the polyamide blades are small and have obvious protrusions in the cross-sectional electron microscope, the surface smoothness is worse, and the roughness of the film increases while the smoothness decreases.

[0054] Comparative Example 2

[0055] The polyamide composite membrane was prepared using essentially the same method as in Example 1, except that the aqueous solution of m-phenylenediamine did not contain carboxymethyl chitosan, but the aqueous solution of acrylic acid contained 1 wt% carboxymethyl chitosan. The surface electron microscope (left) and cross-sectional electron microscope (right) images of the resulting polyamide composite membrane are shown below. Figure 3 As shown. From Figure 3 It can be seen that the polyamide blades are small and have obvious protrusions in the cross-sectional electron microscope, with poor surface smoothness, which is similar to the effect of Comparative Example 1. This indicates that adding carboxymethyl chitosan to the coating layer does not improve the surface structure of the polyamide layer.

[0056] Comparative Example 3

[0057] The polyamide composite film was prepared using essentially the same method as in Example 1, except that 0.05 wt% N,N'-methylenebisacrylamide, 0.2 wt% camphorquinone, and 0.1 wt% acrylic acid were added to an aqueous solution of m-phenylenediamine instead.

[0058] Comparative Example 4

[0059] The polyamide composite film was prepared using essentially the same method as in Example 1, except that carboxymethyl chitosan was not added during the preparation process, and the aqueous solution of 0.05 wt% N,N'-methylenebisacrylamide, 0.2 wt% camphorquinone and 0.1 wt% acrylic acid was replaced with an aqueous solution of 0.2 wt% polyvinyl alcohol.

[0060]

Example 2

[0061] At 25°C, a pre-cut polysulfone-based film was attached to a rectangular frame with sides of 16*12cm. The frame was then immersed in an aqueous solution containing 5wt% p-phenylenediamine, 2wt% carboxymethyl chitosan, 6wt% camphor sulfonic acid, and 3wt% triethylamine for 1 minute. Excess aqueous phase was removed by squeezing with a rubber roller. An organic phase containing 0.5wt% terephthaloyl chloride and n-decane was then poured onto the surface of the polysulfone-based film, and the reaction was allowed to proceed for 2 minutes, with the film surface temperature controlled at 20°C. Excess solution was then removed from the film surface using an air knife, and the film was washed in 90°C hot water for 2 minutes to obtain a composite film containing a modified polyamide layer. An aqueous solution containing 0.05wt% N,N'-methylenebisacrylamide, 0.2wt% camphorquinone, and 0.1wt% acrylic acid was poured onto the surface of the composite film, followed by irradiation under visible light at 35°C for 2 minutes to obtain the polyamide composite film.

[0062]

Example 3

[0063] At 25°C, a pre-cut polysulfone-based film is attached to a rectangular frame with sides of 16*12cm. The frame is then immersed in an aqueous solution containing 2wt% m-phenylenediamine, 0.5wt% hyaluronic acid, 2wt% camphor sulfonic acid, and 1wt% triethylamine for 1 minute. Excess aqueous phase is removed by squeezing with a rubber roller. An organic phase containing 0.05wt% trimesoyl chloride and n-decane is then poured onto the polysulfone-based film surface. The reaction is allowed to proceed for 1.5 minutes, with the film surface temperature controlled at 40°C. The film is then dried to remove excess solution and washed in 90°C hot water for 2 minutes to obtain a composite film containing a modified polyamide layer. An aqueous solution containing 0.2wt% N,N'-methylenebisacrylamide, 0.5wt% isopropylthioxanthone, and 0.5wt% methacrylic acid is poured onto the composite film surface, followed by irradiation under visible light at 45°C for 10 minutes to obtain the polyamide composite film.

[0064]

Example 4

[0065] At 25°C, a pre-cut polysulfone-based film was attached to a rectangular frame with sides of 16*12cm. The frame was then immersed in an aqueous solution containing 4wt% m-phenylenediamine, 0.8wt% aspartic acid, 6wt% camphor sulfonic acid, and 3wt% triethylamine for 1 minute. Excess aqueous phase was removed by squeezing with a rubber roller. An organic phase containing 0.2wt% isoparyl chloride was then poured onto the surface of the polysulfone-based film, and the reaction was allowed to proceed for 1 minute, with the film surface temperature controlled at 30°C. Excess solution was then removed from the film surface using an air knife, and the film was washed in 90°C hot water for 2 minutes to obtain a composite film containing a modified polyamide layer. An aqueous solution containing 0.05wt% N,N'-methylenebisacrylamide, 0.1wt% camphorquinone, and 0.2wt% methacrylic acid was poured onto the surface of the composite film, followed by irradiation under visible light at 80°C for 5 minutes to obtain the polyamide composite film.

[0066]

Example 5

[0067] At 25°C, a pre-cut polysulfone-based film is attached to a rectangular frame with sides of 16*12cm. The frame is then immersed in an aqueous solution containing 3wt% m-phenylenediamine, 1wt% carboxymethyl chitosan, 6wt% camphor sulfonic acid, and 3wt% triethylamine for 1 minute. Excess aqueous phase is removed by squeezing with a rubber roller. An organic phase containing 0.15wt% trimesoyl chloride and n-decane is then poured onto the polysulfone-based film surface. The reaction is allowed to proceed for 1 minute, with the film surface temperature controlled at 25°C. Excess solution is then removed from the film surface using an air knife, and the film is washed in 90°C hot water for 2 minutes to obtain a composite film containing a modified polyamide layer. An aqueous solution containing 0.1wt% N,N'-methylenebisacrylamide, 0.25wt% camphorquinone, and 0.25wt% acrylic acid is poured onto the composite film surface, followed by irradiation under visible light at 40°C for 1 minute to obtain a polyamide composite film.

[0068]

Example 6

[0069] At 25°C, a pre-cut polysulfone-based film was attached to a rectangular frame with sides of 16*12cm. The frame was then immersed in an aqueous solution containing 3.5wt% m-phenylenediamine, 1wt% carboxymethyl chitosan, 6wt% camphor sulfonic acid, and 3wt% triethylamine for 1 minute. Excess aqueous phase was removed by squeezing with a rubber roller. An organic phase containing 0.165wt% pyromellitic acid chloride and n-decane was then poured onto the polysulfone-based film surface. The reaction was allowed to proceed for 0.5 minutes, with the film surface temperature controlled at 40°C. The film was then dried to remove excess solution and washed in 90°C hot water for 2 minutes to obtain a composite film containing a modified polyamide layer. An aqueous solution containing 0.05wt% N,N'-methylenebisacrylamide, 0.1wt% camphorquinone, and 0.1wt% methyl methacrylate was poured onto the composite film surface, followed by irradiation under visible light at 35°C for 8 minutes to obtain the polyamide composite film.

[0070]

Example 7

[0071] At 25°C, a pre-cut polysulfone-based film is attached to a rectangular frame with sides of 16*12cm. The frame is then immersed in an aqueous solution containing 3.5wt% m-phenylenediamine, 1.2wt% carboxymethyl chitosan, 6wt% camphor sulfonic acid, and 3wt% triethylamine for 1 minute. Excess aqueous phase is removed by squeezing with a rubber roller. An organic phase containing 0.165wt% pyromellitic acid chloride and n-decane is then poured onto the polysulfone-based film surface. The reaction is allowed to proceed for 1 minute, with the film surface temperature controlled at 20°C. Excess solution is then removed from the film surface using an air knife, and the film is washed in 90°C hot water for 2 minutes to obtain a composite film containing a modified polyamide layer. An aqueous solution containing 0.1wt% N,N'-methylenebisacrylamide, 0.2wt% camphorquinone, and 0.1wt% methacrylic acid is poured onto the polyamide composite film surface, followed by irradiation under visible light at 25°C for 2 minutes to obtain the polyamide composite film.

[0072]

Example 8

[0073] At 25°C, the cut polysulfone-based membrane is attached to a rectangular frame with sides of 16*12cm. The frame is then immersed in an aqueous solution containing 3.5wt% m-phenylenediamine, 6wt% camphor sulfonic acid, and 3wt% triethylamine for 1 minute. Excess aqueous phase is removed by squeezing with a rubber rod. Then, an organic phase containing 0.165wt% pyromellitic acid chloride and n-decane is poured onto the surface of the polysulfone-based membrane and reacted for 1 minute, with the membrane surface temperature controlled at 25°C. Excess solution on the membrane surface is then removed with an air knife. Subsequently, an aqueous solution containing 1wt% carboxymethyl chitosan is poured onto the membrane surface and reacted for 45 seconds. The solution on the membrane surface is then removed with an air knife, and the membrane is washed in hot water at 90°C for 2 minutes to obtain a composite membrane containing a modified polyamide layer. An aqueous solution containing 0.1 wt% N,N'-methylenebisacrylamide, 0.2 wt% camphorquinone, and 0.15 wt% acrylic acid was poured onto the surface of the composite film, and then irradiated under visible light at an intensity of 50°C for 4 minutes to obtain a polyamide composite film.

[0074] The membrane performance of the polyamide composite membranes prepared in each embodiment and comparative example was tested, and the results are shown in Table 1.

[0075] Table 1. Membrane performance test results

[0076]

[0077]

Claims

1. A method for preparing an antifouling polyamide composite membrane, characterized in that, Includes the following steps: 1) Polyamide is generated by interfacial polymerization of polyamine and polyfunctional acyl chloride on the surface of a porous support, and a modified polyamide layer is prepared by the following method; Before interfacial polymerization, a monomer containing at least one carboxyl group and one amino group is mixed with a polyamine to obtain a modified polyamide layer. or, After interfacial polymerization, a monomer containing at least one carboxyl group and one amino group is coated onto the surface of the polyamide to obtain a modified polyamide layer; 2) A mixture containing a photoinitiator, crosslinking agent, unsaturated acid or ester monomer is coated onto the modified polyamide layer to form a coating layer; 3) The coating layer is subjected to light treatment to initiate a cross-linking polymerization reaction, thereby obtaining an anti-fouling polyamide composite film; In step 1), the monomer containing at least one carboxyl group and one amino group is selected from one or more of carboxymethyl chitosan, hyaluronic acid, aspartic acid, glutamic acid, serine, threonine, and cysteine.

2. The method for preparing the antifouling polyamide composite membrane according to claim 1, characterized in that, The polyamine is selected from one or more of m-phenylenediamine, p-phenylenediamine, piperazine, aliphatic amines, and polyether amines; The polyfunctional acyl chloride is selected from aromatic or alicyclic polyfunctional acyl chlorides.

3. The method for preparing the antifouling polyamide composite membrane according to claim 2, characterized in that, The polyfunctional acyl chloride is selected from one or more of the following: trimesoyl chloride, terephthaloyl chloride, isophthaloyl chloride, biphenyl dicarboxyl chloride, naphthalene dicarboxyl chloride, cyclopropane tricarboxyl chloride, cyclobutane tetracarboxyl chloride, cyclopentane tricarboxyl chloride, cyclopentane tetracarboxyl chloride, cyclohexane tricarboxyl chloride, cyclopentane dicarboxyl chloride, cyclobutane dicarboxyl chloride, cyclohexane dicarboxyl chloride, and tetrahydrofuran dicarboxyl chloride.

4. The method for preparing the antifouling polyamide composite membrane according to claim 2, characterized in that, The polyamine is prepared as a 0.1-20 wt% polar solution before interfacial polymerization, and the polyfunctional acyl chloride is prepared as a 0.01-5 wt% non-polar solution before interfacial polymerization. The two are subjected to interfacial polymerization by coating them onto a porous support or by immersing the porous support in the polar solution and the non-polar solution respectively.

5. The method for preparing the antifouling polyamide composite membrane according to claim 4, characterized in that, The polyamine is prepared as a 2-5 wt% polar solution before interfacial polymerization, and the polyfunctional acyl chloride is prepared as a 0.05-3 wt% nonpolar solution before interfacial polymerization.

6. The method for preparing the antifouling polyamide composite membrane according to claim 1, characterized in that, In step 1), if a monomer containing at least one carboxyl group and one amino group is mixed with a polyamine before interfacial polymerization, the mass concentration ratio of the two is (0.1-2):

1. If a monomer containing at least one carboxyl group and one amino group is coated onto the polyamide surface after interfacial polymerization, the mass concentration of the monomer containing at least one carboxyl group and one amino group is 0.5-2 wt%.

7. The method for preparing the antifouling polyamide composite membrane according to claim 6, characterized in that, In step 1), if a monomer containing at least one carboxyl group and one amino group is mixed with a polyamine before interfacial polymerization, the mass concentration ratio of the two is (0.2-0.5):

1.

8. The method for preparing the antifouling polyamide composite membrane according to any one of claims 1-5, characterized in that, The photoinitiator is selected from one or more of isopropylthioxanthone, camphorquinone, diphenyltitane fluoride, and bis(pentafluorophenyl)titane.

9. The method for preparing the antifouling polyamide composite membrane according to claim 8, characterized in that, The crosslinking agent is N,N'-methylenebisacrylamide.

10. The method for preparing the antifouling polyamide composite membrane according to claim 9, characterized in that, The unsaturated acid or ester monomer is selected from acrylic acid and acrylate monomers.

11. The method for preparing the antifouling polyamide composite membrane according to claim 10, characterized in that, The unsaturated acid or ester monomer is selected from one or more of acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, methyl 2-methacrylate, and ethyl 2-methacrylate.

12. The method for preparing the antifouling polyamide composite membrane according to claim 8, characterized in that, Step 2) In the mixture, the mass concentration of photoinitiator is 0.1-0.5wt%, the mass concentration of crosslinking agent is 0.05-0.2wt%, the mass concentration of unsaturated acid or ester monomer is 0.1-0.5wt%, and the solvent used is one or more of water, methanol, ethanol and isopropanol.

13. The method for preparing the antifouling polyamide composite film according to any one of claims 1-5, characterized in that, Step 3) The light treatment specifically involves visible light irradiation, with a light temperature of 10-80℃ and an irradiation time of 0.5-30min.

14. The method for preparing the antifouling polyamide composite membrane according to claim 13, characterized in that, Step 3) The light treatment specifically involves visible light irradiation, with a light temperature of 35-60℃ and an irradiation time of 1-10 minutes.

15. The method for preparing the antifouling polyamide composite membrane according to any one of claims 1-5, characterized in that, The interfacial polymerization reaction may also optionally include one or more of the following: a phase transfer catalyst, an acid-binding agent, a solubilizer, a complexing agent, and a humectant.

16. The application of an antifouling polyamide composite membrane prepared by the method according to any one of claims 1-15 in the field of reverse osmosis water treatment.

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