Preparation method and application of photo-thermal dual-response membrane material

Abstract

The invention discloses a preparation method and application of a photo-thermal dual-response membrane material, and relates to the field of membrane materials. When the photo-thermal double-response membrane material is prepared, a photo-thermal material firstly reacts with 4-(triethoxysilyl) aniline and then reacts with 2, 4, 6-trihydroxy-1, 3, 5-benzenetricarboxaldehyde and p-phenylenediamine, and a modified photo-thermal material is prepared; the preparation method comprises the following steps: sequentially reacting benzaldehyde with 2-hydroxyacetophenone and 3-N, N-dimethylamino methacryloyl chloride to prepare a photo-initiation monomer; the preparation method comprises the following steps: mixing N-isopropylacrylamide, a photo-initiation monomer, N, N '-methylene bisacrylamide and a modified photo-thermal material, combining with a hydrophobic substrate membrane, preparing a membrane, and finishing the surface by using 2-bromo-1-[3, 5-di (tert-butyl)-4-hydroxyphenyl] ethanone, thereby obtaining the photo-thermal dual-response membrane material. The photo-thermal dual-response membrane material prepared by the invention has the characteristics of pollution resistance, easiness in cleaning, durability, antibacterial property, metal ion recovery and low energy consumption.

Description

Technical Field

[0001] The present invention relates to the field of membrane materials, and in particular to a preparation method and application of a photothermal dual-responsive membrane material. Background Art

[0002] As global water shortages and water pollution become increasingly severe, membrane separation technology is an effective means to solve these problems. The research and development of high-performance membrane materials is also the key to determining the energy efficiency of membrane separation technology. Pollutants pose a great challenge to the long-term stable operation of membrane separation technology. Traditional membrane materials often only have a single hydrophilic or hydrophobic property, but pollutants of different properties in wastewater interact differently with the membrane surface. Therefore, membrane materials with a single interface property are difficult to achieve efficient treatment and resource recovery of wastewater containing multiple types of pollutants.

[0003] In the process of deep treatment of reused sewage and wastewater using membrane separation technology, changes in external environmental conditions are often involved. The membrane materials used are usually hydrophilic membranes or hydrophobic base membranes with relatively simple surface wettability. When multiple different types of pollutants exist in the wastewater at the same time, the pollutants are easily deposited on the membrane surface, causing scaling and membrane pollution and are not easy to wash off, which limits its applicability under variable environmental conditions and the potential to save energy and reduce consumption by utilizing changes in environmental conditions. Therefore, this application introduces a photothermal dual-responsive membrane material. Summary of the Invention

[0004] The purpose of the present invention is to provide a preparation method and application of a photothermal dual-responsive film material to solve the problems existing in the prior art.

[0005] A method for preparing a photothermal dual-responsive film material, the method mainly comprising the following preparation steps:

[0006] (1) polymerizing 1,4-dioxane and 2,4,6-trihydroxy-1,3,5-benzenetricarboxaldehyde, and then reacting with a pre-modified photothermal material to prepare a modified photothermal material;

[0007] (2) The photoinitiator monomer precursor and dichloromethane are mixed uniformly in a mass ratio of 1:44-45, and under nitrogen protection and light-proof conditions, triethylamine with a volume of 0.03-0.04 times that of dichloromethane is added at a uniform rate within 8-10 minutes, and stirred at 200-300 r / min for 18-22 minutes. In an ice bath, 3-N,N-dimethylaminomethyl acryloyl chloride with a molar amount of 1.8-2.2 times that of the photoinitiator monomer precursor is added at a uniform rate within 12-14 minutes, and stirring is continued for 18-22 minutes. Stirring is continued at room temperature for 11-13 hours, and extraction is performed with saturated brine for 3-4 times. The mixture is vacuum dried at 40-50°C for 22-26 hours to obtain a photoinitiator monomer;

[0008] (3) 2-Bromo-1-[3,5-di(tert-butyl)-4-hydroxyphenyl]ethanone, propanol and methanol were mixed evenly in a mass ratio of 1:2-3:12-13 to prepare a surface treatment liquid; the water treatment membrane material was immersed in the surface treatment liquid, ultrasonicated for 30-40 seconds, taken out until no liquid droplets fell, and allowed to stand at 55-65°C for 12-13 hours, and washed with ethanol 3-5 times to prepare a photothermal dual-responsive membrane material.

[0009] As an optimization, the specific operation of polymerizing 1,4-dioxane and 2,4,6-trihydroxy-1,3,5-benzenetricarboxaldehyde in step (1) and then reacting with the pre-modified photothermal material is to mix 1,4-dioxane and 1,3,5-trimethylbenzene in a volume ratio of 1:2.5 to 3.5 to obtain a mixed solvent; 2,4,6-trihydroxy-1,3,5-benzenetricarboxaldehyde, p-phenylenediamine and the mixed solvent in a mass ratio of 1:0.3 to 0.4:18 The mixture was stirred for 3 hours at 400 ° C for 1 h, and the mixture was stirred for 2 hours at 400 ° C for 3 hours. The mixture was ultrasonicated for 9 to 11 minutes, and 0.08 to 0.12 times the volume of the mixed solvent was added with 6M acetic acid aqueous solution. Under nitrogen protection, the mixture was heated to 118 to 122 ° C, and maintained for 35 to 37 hours. An equal amount of pre-modified photothermal material of 2,4,6-trihydroxy-1,3,5-benzenetricarboxaldehyde was added, and the mixture was maintained for 35 to 37 hours. The mixture was washed with N,N-dimethylformamide for 3 to 5 times and vacuum dried at 60 to 70 ° C for 22 to 26 hours.

[0010] As an optimization, the pre-modified photothermal material is prepared by uniformly mixing the photothermal material, 4-(triethoxysilyl)aniline and isopropanol in a mass ratio of 3-5:1:20-30, stirring at 85-95°C and 200-300 r / min for 5-7 hours, centrifuging, washing with deionized water 3-5 times, and drying at 90-100°C for 2.5-3.5 hours.

[0011] As an optimization, the photothermal material includes but is not limited to carbon-based materials such as graphene, carbon nanotubes, silver, copper, MXene, ferroferric oxide and combinations thereof.

[0012] As an optimization, the photoinitiator monomer precursor in step (2) is prepared by uniformly mixing sodium hydroxide and deionized water in a mass ratio of 1:8-10 to obtain a sodium hydroxide aqueous solution; taking 1 part of benzaldehyde, 1 part of 2-hydroxyacetophenone, and 30-40 parts of methanol by mole, stirring the methanol and benzaldehyde at 200-300 r / min for 4-6 minutes, adding 2-hydroxyacetophenone at a uniform speed within 8-10 minutes, continuing to stir for 8-10 minutes, and adding a sodium hydroxide aqueous solution prepared by sodium hydroxide with a molar amount of 3.8-4.2 times that of benzaldehyde at a uniform speed within 13-15 minutes, and continuing to stir for 1 minute. 1 to 13 hours; again measure an equal molar amount of benzaldehyde to prepare a sodium hydroxide aqueous solution with sodium hydroxide, pour it into the reaction solution, then add methanol in an amount 2.8 to 3.2 times the volume of benzaldehyde, and in an ice-water bath, uniformly add a hydrogen peroxide solution with a mass fraction of 29% to 31% at a mass fraction of 0.58 to 0.62 times the volume of benzaldehyde within 14 to 16 minutes, stir at room temperature for 5.8 to 6.2 hours, pour into ice water, adjust the pH to 6.8 to 7.2 with a 0.1 mol / L hydrochloric acid aqueous solution, filter, wash with deionized water 3 to 5 times, and vacuum dry at 40 to 50° C. for 22 to 26 hours to obtain the product.

[0013] As an optimization, the water treatment membrane material in step (3) is prepared by mixing deionized water, N-isopropylacrylamide, photoinitiator monomer, and N,N'-methylenebisacrylamide in a mass ratio of 190-210:0.48-0.62:0.1:0.2-0.3, stirring for 1-2 hours at 50-80°C, 200-400 r / min, and in the dark, adding a modified photothermal material with a mass of 0.01-0.2 times that of N-isopropylacrylamide under nitrogen protection, and ultrasonicating at 0-4°C for 25-35 minutes to prepare a mixed solution of photothermal material and hydrogel prepolymer; combining the photothermal material and hydrogel prepolymer with a hydrophobic base membrane, irradiating under ultraviolet light for 1-3 hours, washing alternately with ethanol and deionized water for 2-4 times, and vacuum drying at 70-80°C for 3-5 hours to obtain the obtained product.

[0014] As an optimization, the hydrophobic base membrane includes but is not limited to polytetrafluoroethylene, polyvinylidene fluoride, and polypropylene.

[0015] As an optimization, the combination of the photothermal material and the hydrogel prepolymer with the hydrophobic substrate membrane includes but is not limited to vacuum filtration, electrospinning and surface graft coating.

[0016] An application of a photothermal dual-responsive membrane material, wherein the application of the photothermal dual-responsive membrane material refers to using the dual-responsive membrane material prepared by the preparation method of a photothermal dual-responsive membrane material according to claim 1 to treat wastewater containing pollutants using membrane separation technology under different external light and temperature environmental conditions;

[0017] The pollutants include but are not limited to inorganic salts, organic matter, surfactants, oils and other types of pollutants;

[0018] The wastewater temperature is between 20 and 80°C, and the light intensity is between 300 and 3000 W / m 2 .

[0019] An application of a photothermal dual-responsive membrane material, wherein the application of the photothermal dual-responsive membrane material refers to the dual-responsive membrane material prepared by the preparation method of a photothermal dual-responsive membrane material according to claim 1 and used for the recovery of resources such as metals, alcohols, ammonia, and inorganic salts.

[0020] As an optimization, the reaction mechanism for synthesizing photoinitiator monomers is as follows:

[0021]

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] When preparing a photothermal dual-responsive membrane material, the present invention first reacts the photothermal material with 4-(triethoxysilyl)aniline and then with 2,4,6-trihydroxy-1,3,5-benzenetricarboxaldehyde and p-phenylenediamine to obtain a modified photothermal material; benzaldehyde is sequentially reacted with 2-hydroxyacetophenone and 3-N,N-dimethylaminomethacryloyl chloride to obtain a photoinitiator monomer; N-isopropylacrylamide, the photoinitiator monomer, N,N'-methylenebisacrylamide and the modified photothermal material are mixed and combined with a hydrophobic base membrane to form a membrane, and then the surface is treated with 2-bromo-1-[3,5-di(tert-butyl)-4-hydroxyphenyl]ethanone to obtain the photothermal dual-responsive membrane material.

[0024] First, the photothermal material was reacted with 4-(triethoxysilyl)aniline and then with 2,4,6-trihydroxy-1,3,5-benzenetricarboxaldehyde and p-phenylenediamine to obtain a modified photothermal material; benzaldehyde was reacted with 2-hydroxyacetophenone and 3-N,N-dimethylaminomethacryloyl chloride in sequence to obtain a photoinitiator monomer; the photothermal material was successfully reacted with 4-(triethoxysilyl)aniline and then with 2,4,6-trihydroxy-1,3,5-benzenetricarboxaldehyde and p-phenylenediamine in the photothermal material. The introduction of COF structure on the surface can adsorb metal ions in sewage, thereby achieving the effect of recycling metal ions in water; through the reaction of benzaldehyde with 2-hydroxyacetophenone and 3-N,N-dimethylaminomethacryloyl chloride in sequence, a monomer with photoinitiating effect is prepared, so that no external photoinitiator is required during film preparation, and a large amount of tertiary amines are formed on the surface during the subsequent generation of poly N-isopropylacrylamide hydrogel, providing sites for the post-finishing of 2-bromo-1-[3,5-di(tert-butyl)-4-hydroxyphenyl]ethanone.

[0025] Secondly, N-isopropylacrylamide, photoinitiator monomer, N,N'-methylenebisacrylamide and modified photothermal material are mixed and combined with a hydrophobic base membrane to form a membrane, and then 2-bromo-1-[3,5-di(tert-butyl)-4-hydroxyphenyl]ethanone is used to finish the surface to obtain a photothermal dual-responsive membrane material; wherein the poly N-isopropylacrylamide hydrogel forms a network structure and is thermosensitive, and the photothermal nanoparticles are embedded in the gel network structure to achieve photothermal dual response. The prepared membrane can switch the interface hydrophilicity and hydrophobicity with changes in light and temperature environmental conditions. It is in a hydrophobic state under light or high temperature conditions, which can reduce the attachment of hydrophilic pollutants. It is in a hydrophilic state under no light or low temperature conditions, which can efficiently wash out hydrophobic pollutants such as oils, and has a wider range of applications, thereby effectively alleviating the membrane pollution problem caused by different types of pollutants and in the cleaning process. It is easy to remove pollutants and achieve efficient anti-fouling and washing of pollutants; 2-bromo-1-[3,5-di(tert-butyl)-4-hydroxyphenyl]ethanone is used for surface finishing, which not only introduces hindered phenols on the membrane surface, but also makes the membrane surface rich in quaternary ammonium salts. Hindered phenols can capture peroxyl free radicals and alkoxy free radicals, blocking chain oxidation reactions. At the same time, the tert-butyl group in the molecule can prevent the formation of phenoxy free radicals as a spatial steric hindering group, thereby preventing new oxidation cycles and achieving the effect of heat-resistant aging; quaternary ammonium salts can combine with the negatively charged phosphate groups on the surface of bacterial cell membranes through positive charges, resulting in changes in membrane permeability, causing small molecules such as potassium ions in the cells to leak out, and ultimately causing cell lysis and death. It can also be inserted into bacterial protein molecules through hydrophobic groups to interfere with the spatial conformation of proteins, resulting in loss of their function and achieving antibacterial effects. DETAILED DESCRIPTION

[0026] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0027] In the following examples and comparative examples, the photothermal material is graphene nanosheets; the hydrophobic substrate membrane is polyvinylidene fluoride; and the photothermal material, the hydrogel prepolymer and the hydrophobic substrate membrane are combined by electrospinning.

[0028] Example 1:

[0029] A method for preparing a photothermal dual-responsive film material mainly includes the following preparation steps:

[0030] (1) The photothermal material, 4-(triethoxysilyl)aniline and isopropanol were mixed in a mass ratio of 3:1:20, stirred at 85 ° C, 200 r / min for 5 h, centrifuged, washed with deionized water 3 times, and dried at 90 ° C for 2.5 h to obtain a pre-modified photothermal material; 1,4-dioxane and 1,3,5-trimethylbenzene were mixed in a volume ratio of 1:2.5 to obtain a mixed solvent; 2,4,6-trihydroxy-1,3,5-benzenetricarboxaldehyde was added. , p-phenylenediamine and a mixed solvent in a mass ratio of 1:0.3:18, ultrasonically treated for 9 minutes, added with a 6M acetic acid aqueous solution with a volume of 0.08 times that of the mixed solvent, heated to 118°C under nitrogen protection, maintained for 35 hours, added with an equal mass of 2,4,6-trihydroxy-1,3,5-benzenetricarboxaldehyde pre-modified photothermal material, continued to maintain for 35 hours, washed with N,N-dimethylformamide three times, and vacuum dried at 60°C for 22 hours to obtain a modified photothermal material;

[0031] (2) Sodium hydroxide and deionized water were mixed uniformly in a mass ratio of 1:8 to prepare a sodium hydroxide aqueous solution; 1 part of benzaldehyde, 1 part of 2-hydroxyacetophenone, and 30 parts of methanol were measured by mole, and the methanol and benzaldehyde were stirred at 200 r / min for 4 minutes, 2-hydroxyacetophenone was added at a uniform rate within 8 minutes, and stirring was continued for 8 minutes. A sodium hydroxide aqueous solution prepared by sodium hydroxide with a molar amount of 3.8 times that of benzaldehyde was added at a uniform rate within 13 minutes, and stirring was continued for 11 hours; a sodium hydroxide aqueous solution prepared by sodium hydroxide with an equal molar amount of benzaldehyde was measured again and poured into the reaction solution, and methanol with a volume of 2.8 times that of benzaldehyde was added. In an ice water bath, a 29% hydrogen peroxide solution with a mass fraction of 0.58 times that of benzaldehyde was added at a uniform rate within 14 minutes, and stirred at room temperature. 5.8h, poured into ice water, adjusted to pH 6.8 with 0.1mol / L hydrochloric acid aqueous solution, filtered, washed 3 times with deionized water, and vacuum dried at 40°C for 22h to obtain a photoinitiator monomer precursor; the photoinitiator monomer precursor and dichloromethane were evenly mixed in a mass ratio of 1:44, and under nitrogen protection and light-proof conditions, triethylamine with a volume of 0.03 times that of dichloromethane was added at a uniform speed within 8min, stirred at 200r / min for 18min, and in an ice bath, 3-N,N-dimethylaminomethylacryloyl chloride with a molar amount of 1.8 times that of the photoinitiator monomer precursor was added at a uniform speed within 12min, and continued stirring for 18min, continued stirring at room temperature for 11h, extracted 3 times with saturated brine, and vacuum dried at 40°C for 22h to obtain a photoinitiator monomer;

[0032] (3) Deionized water, N-isopropylacrylamide, photoinitiator monomer, and N,N'-methylenebisacrylamide were mixed in a mass ratio of 190:0.48:0.1:0.2, stirred at 50°C, 200 r / min, and dark conditions for 1 hour, and then added with a modified photothermal material with a mass of 0.018 times that of N-isopropylacrylamide under nitrogen protection, and ultrasonicated at 0°C for 25 minutes to prepare a mixed solution of photothermal material and hydrogel prepolymer; the photothermal material and hydrogel prepolymer were mixed with a hydrophobic basement membrane. Combined, irradiated under ultraviolet light for 1 hour, washed alternately with ethanol and deionized water twice, and vacuum dried at 70°C for 3 hours to obtain a water treatment membrane material; 2-bromo-1-[3,5-di(tert-butyl)-4-hydroxyphenyl]ethanone, propanol and methanol were mixed evenly in a mass ratio of 1:2:12 to obtain a surface treatment liquid; the water treatment membrane material was immersed in the surface treatment liquid, ultrasonicated for 30 seconds, taken out until no liquid droplets fell, allowed to stand at 55°C for 12 hours, and washed with ethanol three times to obtain a photothermal dual-responsive membrane material.

[0033] Example 2:

[0034] A method for preparing a photothermal dual-responsive film material mainly includes the following preparation steps:

[0035] (1) The photothermal material, 4-(triethoxysilyl)aniline and isopropanol were mixed in a mass ratio of 4:1:25, stirred at 90 °C and 250 r / min for 6 h, centrifuged, washed with deionized water 4 times, and dried at 95 °C for 3 h to prepare a pre-modified photothermal material; 1,4-dioxane and 1,3,5-trimethylbenzene were mixed in a volume ratio of 1:3 to prepare a mixed solvent; 2,4,6-trihydroxy-1,3,5-benzenetricarboxaldehyde, Phenylenediamine and a mixed solvent were mixed in a mass ratio of 1:0.35:19, ultrasonicated for 10 minutes, and a 6M acetic acid aqueous solution with a volume of 0.1 times that of the mixed solvent was added. The mixture was heated to 120°C under nitrogen protection and maintained for 36 hours. An equal amount of pre-modified photothermal material of 2,4,6-trihydroxy-1,3,5-benzenetricarboxaldehyde was added and maintained for another 36 hours. The mixture was washed with N,N-dimethylformamide four times and vacuum dried at 65°C for 24 hours to obtain a modified photothermal material.

[0036] (2) Sodium hydroxide and deionized water were mixed uniformly in a mass ratio of 1:9 to prepare a sodium hydroxide aqueous solution; 1 part of benzaldehyde, 1 part of 2-hydroxyacetophenone, and 35 parts of methanol were measured by mole, and the methanol and benzaldehyde were stirred at 250r / min for 5 minutes, 2-hydroxyacetophenone was added at a uniform rate within 9 minutes, and stirring was continued for 9 minutes. A sodium hydroxide aqueous solution prepared by sodium hydroxide with a molar amount 4 times that of benzaldehyde was added at a uniform rate within 14 minutes, and stirring was continued for 12 hours; a sodium hydroxide aqueous solution prepared by sodium hydroxide with an equal molar amount of benzaldehyde was again measured and poured into the reaction solution, and methanol with a volume 3 times that of benzaldehyde was added. In an ice water bath, a 30% hydrogen peroxide solution with a mass fraction of 0.6 times that of benzaldehyde was added at a uniform rate within 15 minutes, and stirred at room temperature for 6 hours. Pour into ice water, adjust the pH to 7 with 0.1 mol / L hydrochloric acid aqueous solution, filter, wash 4 times with deionized water, and vacuum dry at 45°C for 24 hours to obtain a photoinitiator monomer precursor; mix the photoinitiator monomer precursor and dichloromethane in a mass ratio of 1:44.5, and under nitrogen protection and light-proof conditions, add triethylamine at a constant speed of 0.035 times the volume of dichloromethane within 9 minutes, stir at 250 r / min for 20 minutes, and in an ice bath, add 3-N,N-dimethylaminomethylacryloyl chloride at a constant speed of 2 times the molar amount of the photoinitiator monomer precursor within 13 minutes, continue stirring for 20 minutes, continue stirring at room temperature for 12 hours, extract with saturated brine 3.5 times, and vacuum dry at 450°C for 24 hours to obtain a photoinitiator monomer;

[0037] (3) Deionized water, N-isopropylacrylamide, photoinitiator monomer, and N,N'-methylenebisacrylamide were mixed in a mass ratio of 200:0.5:0.1:0.25, stirred at 65°C, 300 r / min, and dark conditions for 1.5 h, and then added with a modified photothermal material with a mass of 0.02 times that of N-isopropylacrylamide under nitrogen protection, and ultrasonicated at 2°C for 30 min to prepare a mixed solution of photothermal material and hydrogel prepolymer; the photothermal material and hydrogel prepolymer were combined with the hydrophobic basement membrane. , irradiated under ultraviolet light for 2 hours, washed alternately with ethanol and deionized water 3 times, and vacuum dried at 75°C for 4 hours to obtain a water treatment membrane material; 2-bromo-1-[3,5-di(tert-butyl)-4-hydroxyphenyl]ethanone, propanol and methanol were mixed evenly in a mass ratio of 1:2.5:12.5 to obtain a surface treatment liquid; the water treatment membrane material was immersed in the surface treatment liquid, ultrasonicated for 35 seconds, taken out until no liquid droplets fell, allowed to stand at 60°C for 12.5 hours, and washed with ethanol 4 times to obtain a photothermal dual-responsive membrane material.

[0038] Example 3:

[0039] A method for preparing a photothermal dual-responsive film material mainly includes the following preparation steps:

[0040] (1) The photothermal material, 4-(triethoxysilyl)aniline and isopropanol were mixed uniformly in a mass ratio of 5:1:30, stirred at 95°C and 300 r / min for 7 h, centrifuged, washed with deionized water 5 times, and dried at 100°C for 3.5 h to obtain a pre-modified photothermal material; 1,4-dioxane and 1,3,5-trimethylbenzene were mixed uniformly in a volume ratio of 1:3.5 to obtain a mixed solvent; 2,4,6-trihydroxy-1,3,5-benzenetricarboxaldehyde was added. , p-phenylenediamine and a mixed solvent in a mass ratio of 1:0.4:20, ultrasonically treated for 11 minutes, added with a 6M acetic acid aqueous solution with a volume of 0.12 times that of the mixed solvent, heated to 122°C under nitrogen protection, maintained for 37 hours, added with an equal mass of 2,4,6-trihydroxy-1,3,5-benzenetricarboxaldehyde, and continued to maintain for 37 hours, washed with N,N-dimethylformamide 5 times, and vacuum dried at 70°C for 26 hours to obtain a modified photothermal material;

[0041] (2) Sodium hydroxide and deionized water were mixed uniformly in a mass ratio of 1:10 to prepare a sodium hydroxide aqueous solution; 1 part of benzaldehyde, 1 part of 2-hydroxyacetophenone, and 40 parts of methanol were measured by mole, and the methanol and benzaldehyde were stirred at 300 r / min for 6 minutes, 2-hydroxyacetophenone was added at a uniform rate within 10 minutes, and stirring was continued for 10 minutes. A sodium hydroxide aqueous solution prepared by sodium hydroxide with a molar amount of 4.2 times that of benzaldehyde was added at a uniform rate within 15 minutes, and stirring was continued for 13 hours; a sodium hydroxide aqueous solution prepared by sodium hydroxide with an equal molar amount of benzaldehyde was measured again and poured into the reaction solution, and methanol with a volume of 3.2 times that of benzaldehyde was added. In an ice water bath, a 31% hydrogen peroxide solution with a mass fraction of 0.62 times that of benzaldehyde was added at a uniform rate within 16 minutes, and stirred at room temperature. Stir for 6.2 hours, pour into ice water, adjust the pH to 7.2 with 0.1 mol / L hydrochloric acid aqueous solution, filter, wash with deionized water 5 times, and vacuum dry at 50°C for 26 hours to obtain a photoinitiator monomer precursor; mix the photoinitiator monomer precursor and dichloromethane in a mass ratio of 1:45, under nitrogen protection and light-proof conditions, add triethylamine at a constant speed of 0.04 times the volume of dichloromethane within 10 minutes, stir at 300 r / min for 22 minutes, and in an ice bath, add 3-N,N-dimethylaminomethyl acryloyl chloride at a constant speed of 2.2 times the molar amount of the photoinitiator monomer precursor within 14 minutes, continue stirring for 22 minutes, continue stirring at room temperature for 13 hours, extract 4 times with saturated brine, and vacuum dry at 50°C for 26 hours to obtain a photoinitiator monomer;

[0042] (3) Deionized water, N-isopropylacrylamide, photoinitiator monomer, and N,N'-methylenebisacrylamide were mixed in a mass ratio of 210:0.52:0.1:0.3, stirred at 80°C, 400 r / min, and dark conditions for 2 h, and then added with a modified photothermal material with a mass of 0.022 times that of N-isopropylacrylamide under nitrogen protection, and ultrasonicated at 4°C for 35 min to prepare a mixed solution of photothermal material and hydrogel prepolymer; the photothermal material and hydrogel prepolymer were mixed with a hydrophobic basement membrane. Combined, irradiated under ultraviolet light for 3 hours, washed alternately with ethanol and deionized water 4 times, and vacuum dried at 80°C for 5 hours to obtain a water treatment membrane material; 2-bromo-1-[3,5-di(tert-butyl)-4-hydroxyphenyl]ethanone, propanol and methanol were mixed evenly in a mass ratio of 1:3:13 to obtain a surface treatment liquid; the water treatment membrane material was immersed in the surface treatment liquid, ultrasonicated for 40 seconds, taken out until no liquid droplets fell, allowed to stand at 65°C for 13 hours, and washed with ethanol 5 times to obtain a photothermal dual-responsive membrane material.

[0043] Comparative Example 1:

[0044] The preparation method of the photothermal dual-responsive membrane material in Comparative Example 1 differs from that in Example 2 in that the photothermal material is not modified. The remaining steps are the same as in Example 2.

[0045] Comparative Example 2:

[0046] The preparation method of the photothermal dual-responsive membrane material of Comparative Example 2 differs from that of Example 2 in that 2-bromo-1-[3,5-di(tert-butyl)-4-hydroxyphenyl]ethanone is not used for post-treatment. The remaining steps are the same as those of Example 2.

[0047] Test Example 1:

[0048] Anti-pollution test:

[0049] Test method:

[0050] Membrane distillation experiments were carried out on the membranes prepared in each embodiment and comparative example. The water inlet side was maintained at 50°C, the water production side was maintained at 20°C, the intensity of the simulated light source was 1000W / m2, and a mixed aqueous solution with a humic acid concentration of 1g / L and sodium chloride of 3.5wt% was selected as the simulated wastewater for membrane distillation experiments. After 72h of continuous operation, the flux attenuation rate was tested. The flux attenuation rate = [(original flux - water flux after 72h membrane distillation) / original flux] × 100%; pure water was used for the circulating washing experiment using 1000W / m 2 Simulating light illumination, the membrane was cleaned alternately under dark conditions, then light conditions, then dark conditions. Each condition was maintained for 30 minutes. The flux recovery rate was calculated as: flux recovery rate = (water flux after cleaning recovery / original flux) × 100%. The results are shown in Table 1.

[0051] Table 1

[0052] Flux decay rate Flux recovery rate Example 1 38.3％ 91.8％ Example 2 38.5％ 92.0％ Example 3 38.0％ 92.1％ Comparative Example 1 43.1％ 85.7％ Comparative Example 2 40.4％ 85.9％ polyvinylidene fluoride film 83.6％ 26.5％

[0053] From the comparison of the experimental data in Table 1, it can be found that the photothermal dual-responsive membrane material prepared in the present invention has good anti-pollution ability and is easy to clean.

[0054] Test Example 2:

[0055] Photothermal responsiveness test:

[0056] Test method:

[0057] Membrane distillation experiments were conducted on the membranes prepared in each embodiment and comparative example. The inlet and outlet water temperatures were kept at 20°C, and the intensity of the simulated light source was 1000W / m 2 A 24-hour membrane distillation experiment was conducted using a mixed aqueous solution of 1 g / L humic acid and 3.5 wt% sodium chloride as simulated wastewater. The membrane surface temperature was recorded and the solar energy utilization efficiency was calculated: solar energy utilization efficiency = (membrane flux × latent heat of vaporization of water / light intensity) × 100%. The results are shown in Table 2.

[0058] Table 2

[0059]

[0060] From the comparison of the experimental data in Table 2, it can be found that the photothermal dual-responsive membrane material prepared in the present invention has good photothermal response characteristics and high solar energy utilization efficiency, which is beneficial to reducing the energy consumption of the membrane separation process.

[0061] Test Example 3:

[0062] Antibacterial testing:

[0063] Test method: Tested according to GB / T31402-2015, using Staphylococcus aureus and Escherichia coli. Results are shown in Table 3.

[0064] Table 3

[0065]

[0066] From the comparison of the experimental data in Table 3, it can be found that the photothermal dual-responsive membrane material prepared in the present invention has good antibacterial ability.

[0067] From the comparison of the experimental data of Examples 1, 2, 3 and Comparative Example 2 in Table 3, it can be found that the antibacterial rates of Examples 1, 2, and 3 are high. Comparative Example 2 does not use 2-bromo-1-[3,5-di(tert-butyl)-4-hydroxyphenyl]ethanone for surface finishing, which illustrates that tertiary amines are introduced on the membrane surface by reacting benzaldehyde with 2-hydroxyacetophenone and 3-N,N-dimethylaminomethacryloyl chloride in sequence, and quaternary ammonium salts are formed by reacting with 2-bromo-1-[3,5-di(tert-butyl)-4-hydroxyphenyl]ethanone. The quaternary ammonium salt can bind to the negatively charged phosphate groups on the surface of the bacterial cell membrane through positive charge, resulting in changes in membrane permeability, causing small molecules such as potassium ions in the cell to leak out, and ultimately causing cell lysis and death. It can also be inserted into bacterial protein molecules through hydrophobic groups to interfere with the spatial conformation of the protein, resulting in loss of its function and achieving an antibacterial effect.

[0068] Test Example 4:

[0069] Metal ion adsorption test:

[0070] Test method: A 5-cm-diameter circular photothermal dual-responsive membrane was added to 20 mL of a 20 mg / L iron ion solution at room temperature in the dark. The iron ion concentration was measured after 60 minutes. The results are shown in Table 4.

[0071] Table 4

[0072] Iron ion concentration Example 1 2.4mg / L Example 2 2.0mg / L Example 3 2.3mg / L Comparative Example 1 12.6mg / L Comparative Example 2 2.1mg / L

[0073] From the comparison of the experimental data in Table 4, it can be found that the photothermal dual-responsive membrane material prepared in the present invention has good metal ion adsorption capacity.

[0074] From the comparison of the experimental data of Examples 1, 2, and 3 and Comparative Example 1 in Table 4, it can be found that the iron ion concentrations of Examples 1, 2, and 3 are low. The difference between Comparative Example 1 and the embodiment is that the photothermal material is not modified, which shows that the COF structure is successfully introduced on the surface of the photothermal material by first reacting the photothermal material with 4-(triethoxysilyl)aniline and then with 2,4,6-trihydroxy-1,3,5-benzenetricarboxaldehyde and p-phenylenediamine, which can adsorb metal ions in sewage and achieve the effect of recovering metal ions in water.

[0075] Test Example 5:

[0076] Durability test:

[0077] Testing method: A 5-cm-diameter circular photothermal dual-responsive membrane was placed at 80°C for 10 days in the dark at room temperature. The membrane flux was measured and the retention rate was calculated, where retention rate = membrane flux after 10 days / initial flux × 100%. The results are shown in Table 5.

[0078] Table 5

[0079] Retention rate Example 1 95.6％ Example 2 95.8％ Example 3 95.5％ Comparative Example 1 94.7％ Comparative Example 2 86.6％

[0080] From the comparison of the experimental data in Table 5, it can be found that the photothermal dual-responsive film material prepared in the present invention has good durability.

[0081] From the comparison of the experimental data of Examples 1, 2, 3 and Comparative Example 2 in Table 5, it can be found that the retention rates of Examples 1, 2, and 3 are large. The difference between Comparative Example 2 and the embodiment is that 2-bromo-1-[3,5-di(tert-butyl)-4-hydroxyphenyl]ethanone is not used for surface finishing, which shows that the introduction of hindered phenol on the membrane surface can capture peroxyl radicals and alkoxyl radicals, blocking the chain oxidation reaction. At the same time, the tert-butyl group in the molecule as a steric hindering group can prevent the formation of phenoxyl radicals, thereby preventing new oxidation cycles and achieving the effect of heat aging resistance.

[0082] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a photothermal dual-responsive film material, characterized in that: The preparation method of the photothermal dual-responsive film material mainly includes the following preparation steps: (1) polymerizing 1,4-dioxane and 2,4,6-trihydroxy-1,3,5-benzenetricarboxaldehyde, and then reacting with a pre-modified photothermal material to prepare a modified photothermal material; (2) The photoinitiator monomer precursor and dichloromethane are mixed uniformly in a mass ratio of 1:44-45, and under nitrogen protection and light-proof conditions, triethylamine with a volume of 0.03-0.04 times that of dichloromethane is added at a uniform rate within 8-10 minutes, and stirred at 200-300 r / min for 18-22 minutes. In an ice bath, 3-N,N-dimethylaminomethyl acryloyl chloride with a molar amount of 1.8-2.2 times that of the photoinitiator monomer precursor is added at a uniform rate within 12-14 minutes, and stirring is continued for 18-22 minutes. Stirring is continued at room temperature for 11-13 hours, and extraction is performed with saturated brine for 3-4 times. The mixture is vacuum dried at 40-50°C for 22-26 hours to obtain a photoinitiator monomer; (3) 2-Bromo-1-[3,5-di(tert-butyl)-4-hydroxyphenyl]ethanone, propanol and methanol were mixed evenly in a mass ratio of 1:2-3:12-13 to prepare a surface treatment liquid; the water treatment membrane material was immersed in the surface treatment liquid, ultrasonicated for 30-40 seconds, taken out until no liquid droplets fell, and allowed to stand at 55-65°C for 12-13 hours, and washed with ethanol 3-5 times to prepare a photothermal dual-responsive membrane material.

2. The method for preparing a photothermal dual-responsive film material according to claim 1, characterized in that: The specific operation of polymerizing 1,4-dioxane and 2,4,6-trihydroxy-1,3,5-benzenetricarboxaldehyde in step (1) and then reacting with the pre-modified photothermal material is to mix 1,4-dioxane and 1,3,5-trimethylbenzene in a volume ratio of 1:2.5-3.5 to obtain a mixed solvent; 2,4,6-trihydroxy-1,3,5-benzenetricarboxaldehyde, p-phenylenediamine and the mixed solvent in a mass ratio of 1:0.3-0.4:18-20 Mix and ultrasonicate for 9 to 11 minutes, add 6M acetic acid aqueous solution with a volume of 0.08 to 0.12 times of the mixed solvent, heat to 118 to 122 ° C under nitrogen protection, maintain for 35 to 37 hours, add 2,4,6-trihydroxy-1,3,5-benzenetricarboxaldehyde and other pre-modified photothermal materials, continue to maintain for 35 to 37 hours, wash with N,N-dimethylformamide 3 to 5 times, and vacuum dry at 60 to 70 ° C for 22 to 26 hours.

3. The method for preparing a photothermal dual-responsive film material according to claim 2, characterized in that: The pre-modified photothermal material is prepared by uniformly mixing a photothermal material, 4-(triethoxysilyl)aniline and isopropyl alcohol in a mass ratio of 3-5:1:20-30, stirring at 85-95° C. and 200-300 r / min for 5-7 hours, centrifuging, washing with deionized water for 3-5 times, and drying at 90-100° C. for 2.5-3.5 hours.

4. The method for preparing a photothermal dual-responsive film material according to claim 3, characterized in that: The photothermal materials include but are not limited to carbon-based materials such as graphene, carbon nanotubes, silver, copper, MXene, ferrosoferric oxide, and combinations thereof.

5. The method for preparing a photothermal dual-responsive film material according to claim 1, characterized in that: The photoinitiator monomer precursor in step (2) is prepared by uniformly mixing sodium hydroxide and deionized water in a mass ratio of 1:8-10 to obtain a sodium hydroxide aqueous solution; taking 1 part of benzaldehyde, 1 part of 2-hydroxyacetophenone, and 30-40 parts of methanol by mole, stirring the methanol and benzaldehyde at 200-300 r / min for 4-6 minutes, adding 2-hydroxyacetophenone at a uniform speed within 8-10 minutes, continuing to stir for 8-10 minutes, and adding a sodium hydroxide aqueous solution prepared by sodium hydroxide with a molar amount of 3.8-4.2 times that of benzaldehyde at a uniform speed within 13-15 minutes, and continuing to stir for 11- 13h; again measure the sodium hydroxide aqueous solution prepared with an equal molar amount of benzaldehyde and pour it into the reaction solution, then add methanol in an amount of 2.8 to 3.2 times the volume of benzaldehyde, and in an ice-water bath, uniformly add a hydrogen peroxide solution with a mass fraction of 29% to 31% at a volume of 0.58 to 0.62 times the volume of benzaldehyde within 14 to 16 minutes, stir at room temperature for 5.8 to 6.2 hours, pour into ice water, adjust the pH to 6.8 to 7.2 with a 0.1 mol / L hydrochloric acid aqueous solution, filter, wash with deionized water 3 to 5 times, and vacuum dry at 40 to 50°C for 22 to 26 hours to obtain.

6. The method for preparing a photothermal dual-responsive film material according to claim 1, characterized in that: The water treatment membrane material in step (3) is prepared by mixing deionized water, N-isopropylacrylamide, a photoinitiator monomer, and N,N'-methylenebisacrylamide in a mass ratio of 190-210:0.48-0.62:0.1:0.2-0.3, stirring for 1-2 hours at 50-80°C, 200-400 r / min, and in the dark, adding a modified photothermal material with a mass of 0.01-0.2 times that of N-isopropylacrylamide under nitrogen protection, and ultrasonicating at 0-4°C for 25-35 minutes to prepare a mixed solution of photothermal material and hydrogel prepolymer; combining the photothermal material and the hydrogel prepolymer with a hydrophobic basement membrane, irradiating the solution under ultraviolet light for 1-3 hours, washing the solution alternately with ethanol and deionized water for 2-4 times, and vacuum drying the solution at 70-80°C for 3-5 hours.

7. The method for preparing a photothermal dual-responsive film material according to claim 6, characterized in that: The hydrophobic base membrane includes but is not limited to polytetrafluoroethylene, polyvinylidene fluoride, and polypropylene.

8. The method for preparing a photothermal dual-responsive film material according to claim 6, characterized in that: The combination of the photothermal material and the hydrogel prepolymer with the hydrophobic base membrane includes, but is not limited to, vacuum filtration, electrostatic spinning, and surface graft coating.

9. Application of a photothermal dual-responsive membrane material, characterized in that: The application of the photothermal dual-responsive membrane material refers to the use of the dual-responsive membrane material prepared by the preparation method of a photothermal dual-responsive membrane material according to claim 1 for treating wastewater containing pollutants using membrane separation technology under different external light and temperature environmental conditions; The pollutants include but are not limited to inorganic salts, organic matter, surfactants, oils and other types of pollutants; The wastewater temperature is between 20 and 80°C, and the light intensity is between 300 and 3000 W / m 2 .

10. Application of a photothermal dual-responsive membrane material, characterized in that: The application of the photothermal dual-responsive membrane material refers to the use of the dual-responsive membrane material prepared by the preparation method of a photothermal dual-responsive membrane material according to claim 1 for the recovery of resources such as metals, alcohols, ammonia, and inorganic salts.

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