Preparation method of anti-pollution modified polyether sulfone nanofiltration membrane

Abstract

The invention discloses a preparation method of an anti-pollution modified polyethersulfone nanofiltration membrane, which comprises the following steps: step A1, preparation of a membrane casting solution and a coagulating bath: dissolving polyethersulfone, a zwitterionic block copolymer, tetrazine modified graphene quantum dots and tetrabutyl titanate in N-methyl pyrrolidone to obtain the membrane casting solution; the zwitterionic block copolymer forms a dynamic hydration layer through strong hydration to inhibit pollutant adsorption; dissolving calcium chloride and disodium hydrogen phosphate in deionized water, adding triethanolamine to adjust the pH value of the solution to 8.0-9.0, continuously stirring, and adding norbornene modified chitosan in the stirring process to obtain a coagulating bath; the invention relates to the technical field of nanofiltration membranes. According to the preparation method of the anti-pollution modified polyethersulfone nanofiltration membrane, vertical array hydroxyapatite whiskers generated by biomimetic mineralization provide a super-hydrophilic surface to reduce organic matter adhesion; the tetrazine-norbornene light-triggered dynamic cross-linked network endows the film surface with self-repairing capability, and the use damage can be repaired.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of nanofiltration membranes, in particular to a preparation method of an anti-pollution modified polyether sulfone nanofiltration membrane. BACKGROUND

[0002] Traditional polyether sulfone nanofiltration membranes are easily polluted by organic matters due to hydrophobicity, resulting in flux attenuation and shortened service life. Existing modification technologies such as blending hydrophilic additives can improve the anti-pollution property, but problems such as additive dissolution and weak interfacial bonding exist; surface coating is easily stripped by hydraulic shear. The biomimetic mineralization strategy can construct a hydrophilic layer, but the disorderly grown hydroxyapatite whiskers easily block the membrane pores, reducing the water flux.

[0003] In addition, the performance of the membrane material is easily degraded under extreme pH or mechanical damage, and existing self-repairing technologies mostly rely on chemical stimulation or high-temperature treatment, which is difficult to realize in-situ precise repair.

[0004] Although the introduction of nanomaterials (such as graphene quantum dots) can enhance the separation performance, the poor dispersibility of the nanomaterials easily causes agglomeration defects, and the function is single. At the same time, the traditional coagulation bath phase separation process lacks regulation precision, and the fluctuation of mineralization pH leads to uneven structure, affecting the integrity of the membrane. It is urgent to develop a modification strategy that takes into account long-term anti-pollution, high flux, self-repairing and mechanical stability, and to break through the existing technical bottlenecks through multi-component synergy and process innovation. SUMMARY

[0005] To achieve the above purpose, the application is implemented by the following technical scheme: an anti-pollution modified polyether sulfone nanofiltration membrane comprises the following components:

[0006] The casting solution components are as follows: polyether sulfone 80-120 parts by mass, zwitterionic block copolymer 30-50 parts by mass, tetrazine-modified graphene quantum dots 2-5 parts by mass, tetrabutyl titanate 6-18 parts by mass, and N-methyl pyrrolidone 480-550 parts by mass;

[0007] The coagulation bath components are as follows: deionized water 300-320 parts by mass, calcium chloride 5.5-8.5 parts by mass, disodium hydrogen phosphate 4.0-6.5 parts by mass, norbornene-modified chitosan 3-8 parts by mass, and triethanolamine 1.2-2 parts by mass.

[0008] Preferably, the following components are included:

[0009] The casting solution components are as follows: polyether sulfone 100 parts by mass, zwitterionic block copolymer 40 parts by mass, tetrazine-modified graphene quantum dots 3.5 parts by mass, tetrabutyl titanate 12 parts by mass, and N-methyl pyrrolidone 500 parts by mass;

[0010] Coagulation bath components: 310 parts by mass of deionized water, 7 parts by mass of calcium chloride, 5 parts by mass of disodium hydrogen phosphate, 5.5 parts by mass of norbornene modified chitosan, and 1.6 parts by mass of triethanolamine.

[0011] Preferably, the zwitterionic block copolymer is specifically poly(sulfobetaine)-b-poly(dopamine acrylamide), and the block molar ratio is (3-4):1.

[0012] A preparation method of an anti-pollution modified polyether sulfone nanofiltration membrane, comprising the following steps:

[0013] Step A1, preparation of casting solution and coagulation bath:

[0014] Dissolve polyether sulfone, zwitterionic block copolymer, tetrazine modified graphene quantum dots and tetrabutyl titanate in N-methyl pyrrolidone to obtain a casting solution;

[0015] The zwitterionic block copolymer forms a dynamic hydration layer through strong hydration to inhibit the adsorption of pollutants.

[0016] Dissolve calcium chloride and disodium hydrogen phosphate in deionized water, adjust the pH value of the solution to 8.0-9.0 by adding triethanolamine, and continuously stir, and add norbornene modified chitosan during stirring to obtain a coagulation bath;

[0017] Step A2, preparation of biomimetic mineralization film; the casting solution is scraped into a film, immersed in the coagulation bath, and the pH value is controlled at 7.0-9.0 to induce the formation of a hydroxyapatite whisker layer on the surface of the film; the vertical array of hydroxyapatite whiskers formed by biomimetic mineralization provides a super-hydrophilic surface to reduce the adhesion of organic matter;

[0018] Step A3, near-infrared light dynamic crosslinking; place the wet film in a solution containing norbornene modified chitosan, and irradiate with near-infrared light with a wavelength of 800-850 nm and a power density of 0.5-1.5 W / cm 2 The reverse electron demand Diels-Alder reaction of the tetrazine group and the norbornene group is triggered; the tetrazine-norbornene photo-triggered dynamic crosslinking network endows the film surface with self-repairing ability, which can repair the damage.

[0019] Step A4, post-curing treatment; heat treatment at 60-80℃ for 20-40 minutes to complete the oxidation crosslinking of pyrocatechol, and obtain the modified polyether sulfone nanofiltration membrane; the pyrocatechol oxidation crosslinking constructs a covalent network to resist extreme environments with pH 2-12; the photo-triggered iEDDA reaction anchors the norbornene modified chitosan on the surface of the film, resisting the peeling of water shear.

[0020] Preferably, the casting solution in step A1 is prepared by a step-by-step dissolution method, specifically including the following steps:

[0021] Step S1, dissolving polyether sulfone in part of N-methyl pyrrolidone to form a base solution;

[0022] Step S2, ultrasonic dispersion of the zwitterionic block copolymer and Tz-GQDs in the remaining N-methyl pyrrolidone, adding 0.1-0.5wt% silane coupling agent KH-550 to obtain a premix solution;

[0023] Step S3, adding the premix solution to the base solution, adding a solution of tetrabutyl titanate containing 0.1-0.3wt% acetylacetone after stirring at 50-60℃ for 2-4 hours. Through the chelation of tetrabutyl titanate in acetylacetone to form TiO2 inorganic crosslinking points, the tensile strength is improved.

[0024] Preferably, the particle size of the tetrazine modified graphene quantum dots in step A1 is 3-5nm, and the density of tetrazine groups is ≥8 per quantum dot. The tetrazine modified graphene quantum dots embedded in the polymer network enhance the screening precision and improve the retention rate of divalent salt; the gradient pH mineralization precisely controls the whisker orientation to avoid pore blockage.

[0025] Preferably, in step A2, gradient pH mineralization is used:

[0026] The pH is maintained at 9.0 for the first 1-3 minutes, then reduced to pH 7.0-7.5 at a rate of 0.5pH / min and maintained for 5-10 minutes.

[0027] Preferably, in step A2, the hydroxyapatite whisker layer is arranged in a vertical array, the length is 100-500nm, and the coverage density is 10-30 roots / μm 2 The vertical arrangement of hydroxyapatite whiskers constructs regular nanochannels to reduce water transport resistance, and the flux is increased by more than 40%.

[0028] Near-infrared light dynamic crosslinking realizes non-contact precise curing, energy consumption is reduced by 50%; stepwise dissolution method combined with KH-550 silane coupling agent ensures uniform dispersion of Tz-GQDs; the coagulation bath triethanolamine / disodium hydrogen phosphate buffer system maintains the pH stability of mineralization and reduces structural defects.

[0029] Tetrazine-GQDs have both photo-thermal conversion (near-infrared absorption rate >90%) and crosslinking site functions; norbornene modified chitosan has the dual roles of regulating phase separation rate and photocrosslinking monomer; optimizing the molar ratio of block copolymer (3-4):1 balances hydrophilicity / adhesion, strengthens anti-fouling and interface binding synergistic effect.

[0030] The application provides a preparation method of an anti-pollution modified polyether sulfone nanofiltration membrane.

[0031] (I) The preparation method of the anti-pollution modified polyether sulfone nanofiltration membrane, which forms a dynamic hydration layer by strong hydration of the zwitterionic block copolymer to inhibit the adsorption of pollutants; the biomimetic mineralization of the vertically arranged hydroxyapatite whiskers provides a super-hydrophilic surface to reduce the adhesion of organic matter; the light-triggered dynamic crosslinking network of tetrazine-norbornene endows the membrane surface with self-repairing ability, which can repair the use damage.

[0032] (II) The preparation method of the anti-pollution modified polyether sulfone nanofiltration membrane, which reduces the water transport resistance by constructing regular nanochannels through vertically arranged hydroxyapatite whiskers, and the flux is increased by more than 40%; tetrazine-modified graphene quantum dots are embedded in the polymer network to enhance the screening precision and improve the rejection rate of divalent salt; gradient pH mineralization precisely controls the orientation of the whiskers to avoid pore blockage.

[0033] (III) The preparation method of the anti-pollution modified polyether sulfone nanofiltration membrane, which forms TiO2 inorganic crosslinking points by chelation of titanium tetrabutoxide with acetylacetone, making the tensile strength increase by 35%; the covalent network is constructed by catechol oxidation crosslinking to resist extreme environments with pH 2-12; the light-triggered iEDDA reaction anchors norbornene-modified chitosan on the membrane surface to resist water shear peeling.

[0034] (IV) The preparation method of the anti-pollution modified polyether sulfone nanofiltration membrane, which realizes non-contact precise curing through near-infrared light dynamic crosslinking, reducing energy consumption by 50%; the step-by-step dissolution method combined with KH-550 silane coupling agent ensures uniform dispersion of Tz-GQDs; the coagulation bath of triethanolamine / dibasic sodium phosphate buffer system maintains the pH stability of mineralization, reducing structural defects.

[0035] (V) The preparation method of the anti-pollution modified polyether sulfone nanofiltration membrane, which has both light-heat conversion and crosslinking site functions through tetrazine-GQDs; norbornene-modified chitosan has the dual roles of regulating phase separation rate and photocrosslinking monomer; the optimized molar ratio of block copolymer (3-4):1 balances hydrophilicity / adhesion, strengthening the synergistic effect of anti-pollution and interface combination. DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor belong to the scope of protection of the present application.

[0037] Embodiment one, the present application provides a technical solution:

[0038] An anti-pollution modified polyether sulfone nanofiltration membrane, comprising the following components:

[0039] Casting solution components: 80 parts by mass of polyether sulfone, 30 parts by mass of zwitterionic block copolymer, 2 parts by mass of tetrazine modified graphene quantum dots, 6 parts by mass of tetrabutyl titanate, and 480 parts by mass of N-methyl pyrrolidone;

[0040] Coagulation bath components: 300 parts by mass of deionized water, 5.5 parts by mass of calcium chloride, 4.0 parts by mass of disodium hydrogen phosphate, 3 parts by mass of norbornene modified chitosan, and 1.2 parts by mass of triethanolamine.

[0041] The zwitterionic block copolymer is specifically poly(sulfobetaine)-b-poly(dopamine acrylamide), and the block molar ratio is 3:1.

[0042] A preparation method of a pollution-resistant modified polyether sulfone nanofiltration membrane, comprising the following steps:

[0043] Step A1, preparation of casting solution and coagulation bath:

[0044] Dissolve the polyether sulfone, zwitterionic block copolymer, tetrazine modified graphene quantum dots, and tetrabutyl titanate in N-methyl pyrrolidone to obtain a casting solution;

[0045] The casting solution is prepared by a step-by-step dissolution method, specifically including the following steps:

[0046] Step S1, dissolve the polyether sulfone in part of the N-methyl pyrrolidone to form a base solution;

[0047] Step S2, ultrasonically disperse the zwitterionic block copolymer and Tz-GQDs in the remaining N-methyl pyrrolidone, and add 0.1wt% silane coupling agent KH-550 to obtain a premix;

[0048] Step S3, add the premix to the base solution, and after stirring at 50°C for 2 hours, add a tetrabutyl titanate solution containing 0.1wt% acetylacetone. TiO2 inorganic cross-linking points are formed through the chelation of tetrabutyl titanate in acetylacetone, which improves the tensile strength.

[0049] The particle size of the tetrazine modified graphene quantum dots is 3nm, and the density of tetrazine groups is ≥8 per quantum dot. The embedding of tetrazine modified graphene quantum dots into the polymer network enhances the screening precision and improves the divalent salt retention rate; the gradient pH mineralization precisely controls the whisker orientation to avoid pore blockage.

[0050] The zwitterionic block copolymer forms a dynamic hydration layer through strong hydration to inhibit the adsorption of pollutants.

[0051] Dissolve calcium chloride and disodium hydrogen phosphate in deionized water, adjust the pH value of the solution to 8.0 by adding triethanolamine, and continuously stir. Add norbornene modified chitosan during stirring to obtain a coagulation bath;

[0052] Step A2, biomimetic mineralization film formation; the casting solution is scraped into a film, immersed in a coagulation bath, the pH value is controlled at 7.0, and a hydroxyapatite whisker layer is induced to form on the surface of the film; the vertical array hydroxyapatite whisker formed by biomimetic mineralization provides a super-hydrophilic surface to reduce the adhesion of organic matter;

[0053] The hydroxyapatite whisker layer is arranged in a vertical array, the length is 100 nm, and the coverage density is 10 roots per mu 2 The vertical arrangement of the hydroxyapatite whisker constructs a regular nanochannel to reduce the water transmission resistance, and the flux is increased by more than 40%.

[0054] Step A3, near-infrared light dynamic crosslinking; the wet film is placed in a solution containing norbornene modified chitosan, near-infrared light with a wavelength of 800 nm and a power density of 0.5 W / cm 2 The reverse electron demand Diels-Alder reaction of the tetrazine group and the norbornene group is triggered; the tetrazine-norbornene photo-triggered dynamic crosslinking network endows the film surface with self-repairing ability, which can repair the use damage.

[0055] Gradient pH mineralization is used: the pH is maintained at 9.0 for the first minute, then decreased to pH 7.0 at a rate of 0.5 pH / min and maintained for 5 minutes.

[0056] Step A4, post-curing treatment; heat treatment at 60 DEG C for 20 minutes to complete the oxidation crosslinking of pyrocatechol, and obtain a modified polyether sulfone nanofiltration membrane; the oxidation crosslinking of pyrocatechol constructs a covalent network to resist extreme environments with pH of 2-12; the photo-triggered iEDDA reaction anchors the norbornene modified chitosan on the membrane surface to resist the peeling of water shear.

[0057] The near-infrared light dynamic crosslinking realizes non-contact precise curing, and the energy consumption is reduced by 50%; the step-by-step dissolution method combined with KH-550 silane coupling agent ensures the uniform dispersion of Tz-GQDs; the coagulation bath triethanolamine / disodium hydrogen phosphate buffer system maintains the pH stability of mineralization, and reduces the structural defects.

[0058] The tetrazine-GQDs have the functions of photo-thermal conversion and crosslinking sites; the norbornene modified chitosan has the dual roles of regulating the phase separation rate and photo-crosslinking monomer; the optimization of the molar ratio of the block copolymer 3:1 balances the hydrophilicity / adhesion, and strengthens the synergistic effect of anti-fouling and interface combination.

[0059] Embodiment two, the application provides a technical scheme:

[0060] An anti-pollution modified polyether sulfone nanofiltration membrane comprises the following components:

[0061] The casting solution components are: polyether sulfone 120 parts by mass, zwitterionic block copolymer 50 parts by mass, tetrazine modified graphene quantum dots 5 parts by mass, tetrabutyl titanate 18 parts by mass, and N-methyl pyrrolidone 550 parts by mass.

[0062] Coagulation bath components: 320 parts by mass of deionized water, 8.5 parts by mass of calcium chloride, 6.5 parts by mass of disodium hydrogen phosphate, 8 parts by mass of norbornene modified chitosan, and 2 parts by mass of triethanolamine.

[0063] The zwitterionic block copolymer is specifically polysulfobetaine-b-polydopamine acrylamide, and the block molar ratio is 4:1.

[0064] A preparation method of a pollution-resistant modified polyether sulfone nanofiltration membrane, comprising the following steps:

[0065] Step A1, preparation of casting solution and coagulation bath:

[0066] Dissolve polyether sulfone, zwitterionic block copolymer, tetrazine modified graphene quantum dots and tetrabutyl titanate in N-methyl pyrrolidone to obtain a casting solution;

[0067] The casting solution is prepared by a step-by-step dissolution method, specifically comprising the following steps:

[0068] Step S1, dissolve polyether sulfone in part of N-methyl pyrrolidone to form a base solution;

[0069] Step S2, ultrasonically disperse the zwitterionic block copolymer and Tz-GQDs in the remaining N-methyl pyrrolidone, and add 0.5wt% silane coupling agent KH-550 to obtain a premix;

[0070] Step S3, add the premix to the base solution, and after stirring at 60°C for 4 hours, add a tetrabutyl titanate solution containing 0.3wt% acetylacetone. TiO2 inorganic crosslinking points are formed through the chelation of tetrabutyl titanate in acetylacetone, so that the tensile strength is improved.

[0071] The particle size of the tetrazine modified graphene quantum dots is 5nm, and the density of tetrazine groups is ≥8 / quantum dot. The embedding of tetrazine modified graphene quantum dots in the polymer network enhances the screening precision and improves the divalent salt retention rate; the gradient pH mineralization precisely controls the whisker orientation to avoid pore blockage.

[0072] The zwitterionic block copolymer forms a dynamic hydration layer through strong hydration to inhibit the adsorption of pollutants.

[0073] Dissolve calcium chloride and disodium hydrogen phosphate in deionized water, adjust the pH value of the solution to 9.0 by adding triethanolamine, and continuously stir. Add norbornene modified chitosan during the stirring process to obtain a coagulation bath;

[0074] Step A2, preparation of biomimetic mineralization film forming; the casting solution is scraped into a film, immersed in the coagulation bath, and the pH value is controlled at 9.0 to induce the formation of a hydroxyapatite whisker layer on the surface of the film; the vertical array of hydroxyapatite whiskers formed by biomimetic mineralization provides a super-hydrophilic surface to reduce the adhesion of organic matter;

[0075] Hydroxyapatite whisker layer is arranged in a vertical array, with a length of 500 nm and a coverage density of 30 roots per mu 2 The vertical arrangement of the hydroxyapatite whiskers reduces the water transmission resistance and increases the flux by more than 40%.

[0076] Step A3, near-infrared light dynamic crosslinking; the wet film is placed in a solution containing norbornene modified chitosan, and near-infrared light with a wavelength of 850 nm and a power density of 1.5 W / cm 2 The reverse electron demand Diels-Alder reaction of the tetrazine group and the norbornene group is triggered; the tetrazine-norbornene light-triggered dynamic crosslinking network endows the film surface with self-repairing ability, which can repair the damage.

[0077] Gradient pH mineralization is used: maintain pH 9.0 for the first 3 minutes, then reduce to pH 7.5 at a rate of 0.5 pH / min and maintain for 10 minutes.

[0078] Step A4, post-curing treatment; heat treatment at 80℃ for 40 minutes to complete the oxidation crosslinking of catechol, and obtain the modified polyether sulfone nanofiltration membrane; the oxidation crosslinking of catechol constructs a covalent network to resist extreme environments with pH 2-12; the light-triggered iEDDA reaction anchors the norbornene modified chitosan on the membrane surface, resisting the peeling of water shear.

[0079] Non-contact precise curing is realized by near-infrared light dynamic crosslinking, which reduces energy consumption by 50%; the step-by-step dissolution method combined with KH-550 silane coupling agent ensures uniform dispersion of Tz-GQDs; the coagulation bath triethanolamine / disodium hydrogen phosphate buffer system maintains the stability of the mineralization pH, reducing structural defects.

[0080] Tetrazine-GQDs have both light-to-heat conversion and crosslinking site functions; norbornene modified chitosan has the dual roles of regulating phase separation rate and photocrosslinking monomer; the optimized block copolymer molar ratio of 4:1 balances hydrophilicity / adhesion, strengthening the synergistic effect of antifouling and interface combination.

[0081] Example Three, the present application provides a technical scheme:

[0082] A pollution-resistant modified polyether sulfone nanofiltration membrane comprises the following components:

[0083] The casting solution components are: polyether sulfone 120 parts by mass, zwitterionic block copolymer 30 parts by mass, tetrazine modified graphene quantum dots 5 parts by mass, tetrabutyl titanate 6 parts by mass, and N-methyl pyrrolidone 550 parts by mass;

[0084] Coagulation bath components: 300 parts by mass of deionized water, 8.5 parts by mass of calcium chloride, 4.0 parts by mass of disodium hydrogen phosphate, 8 parts by mass of norbornene modified chitosan, and 1.2 parts by mass of triethanolamine.

[0085] The zwitterionic block copolymer is specifically poly(sulfobetaine)-b-poly(dopamine acrylamide), and the block molar ratio thereof is 3:1.

[0086] A preparation method of a pollution-resistant modified polyether sulfone nanofiltration membrane, comprising the following steps:

[0087] Step A1, preparation of casting solution and coagulation bath:

[0088] The polyether sulfone, the zwitterionic block copolymer, the tetrazine modified graphene quantum dot and the tetrabutyl titanate are dissolved in N-methyl pyrrolidone to obtain a casting solution;

[0089] The casting solution is prepared by a step-by-step dissolution method, specifically comprising the following steps:

[0090] Step S1, dissolving the polyether sulfone in part of the N-methyl pyrrolidone to form a base solution;

[0091] Step S2, ultrasonic dispersion of the zwitterionic block copolymer and the Tz-GQDs in the remaining N-methyl pyrrolidone, and addition of 0.1wt% silane coupling agent KH-550 to obtain a premix;

[0092] Step S3, adding the premix to the base solution, and then adding a tetrabutyl titanate solution containing 0.3wt% acetylacetone after stirring at 60°C for 2 hours. TiO2 inorganic crosslinking points are formed through chelation of tetrabutyl titanate in acetylacetone, so that the tensile strength is improved.

[0093] The tetrazine modified graphene quantum dot has a particle size of 3nm, and the density of tetrazine groups is ≥8 / quantum dot. The tetrazine modified graphene quantum dot embedded in the polymer network enhances the screening precision and improves the divalent salt retention rate; the gradient pH mineralization precisely controls the whisker orientation to avoid pore blockage.

[0094] The zwitterionic block copolymer forms a dynamic hydration layer through strong hydration to inhibit the adsorption of pollutants.

[0095] The calcium chloride and the disodium hydrogen phosphate are dissolved in deionized water, triethanolamine is added to adjust the pH value of the solution to 8.0, and stirring is continuously performed. The norbornene modified chitosan is added during the stirring process to obtain a coagulation bath.

[0096] Step A2, preparation of biomimetic mineralization film formation; the casting solution is scraped into a film, immersed in the coagulation bath, and the pH value is controlled at 9.0 to induce the formation of a hydroxyapatite whisker layer on the surface of the film; the vertical array of hydroxyapatite whiskers formed by biomimetic mineralization provides a super-hydrophilic surface to reduce the adhesion of organic matter;

[0097] The hydroxyapatite whisker layer is arranged in a vertical array, with a length of 100 nm and a coverage density of 30 whiskers / μm 2 The vertical arrangement of hydroxyapatite whiskers creates regular nanochannels that reduce water transport resistance and increase water flux by more than 40%.

[0098] Step A3, near-infrared dynamic crosslinking: the wet film is placed in a solution containing norbornene-modified chitosan, using a wavelength of 850nm and a power density of 0.5W / cm 2 Irradiation with near-infrared light triggers the reverse electron demand Diels-Alder reaction between the tetrazine group and the norbornene group; the tetrazine-norbornene light-triggered dynamic cross-linking network gives the membrane surface self-healing ability, which can repair damage caused by use.

[0099] Gradient pH mineralization was performed: pH was maintained at 9.0 for the first 3 minutes, then decreased to pH 7.5 at a rate of 0.5 pH / min and maintained for 10 minutes.

[0100] Step A4, post-curing treatment; heat treatment at 60°C for 20 minutes to complete the oxidative cross-linking of catechol to obtain a modified polyethersulfone nanofiltration membrane; oxidative cross-linking of catechol to construct a covalent network that can withstand extreme environments of pH 2-12; light-triggered iEDDA reaction to anchor norbornene-modified chitosan to the membrane surface to resist hydraulic shear peeling.

[0101] Near-infrared light dynamic crosslinking achieves non-contact precision curing, reducing energy consumption by 50%; the step-by-step dissolution method combined with KH-550 silane coupling agent ensures uniform dispersion of Tz-GQDs; the coagulation bath triethanolamine / disodium hydrogen phosphate buffer system maintains the pH stability of mineralization and reduces structural defects.

[0102] Tetrazine-GQDs simultaneously possess photothermal conversion (near-infrared absorptivity >90%) and cross-linking site functions; norbornene-modified chitosan serves as both a phase separation rate regulator and a photocross-linking monomer; and an optimized block copolymer molar ratio of 3:1 balances hydrophilicity / adhesion, enhancing the synergistic anti-fouling and interfacial binding effects.

[0103] Embodiment 4: The present invention provides a technical solution:

[0104] A pollution-resistant modified polyethersulfone nanofiltration membrane comprises the following components:

[0105] Casting solution components: 100 parts by mass of polyethersulfone, 40 parts by mass of zwitterionic block copolymer, 3 parts by mass of tetrazine-modified graphene quantum dots, 12 parts by mass of tetrabutyl titanate, and 500 parts by mass of N-methylpyrrolidone;

[0106] Coagulation bath components: 300 parts by mass of deionized water, 7 parts by mass of calcium chloride, 5 parts by mass of disodium hydrogen phosphate, 5 parts by mass of norbornene-modified chitosan, and 1.5 parts by mass of triethanolamine.

[0107] The zwitterionic block copolymer is specifically poly sulfobetaine-b-polydopamine acrylamide, and the block molar ratio is 3.5:1.

[0108] A preparation method of an anti-pollution modified polyether sulfone nanofiltration membrane, comprising the following steps:

[0109] Step A1, preparation of casting solution and coagulation bath:

[0110] Dissolve polyether sulfone, zwitterionic block copolymer, tetrazine modified graphene quantum dots and tetrabutyl titanate in N-methyl pyrrolidone to obtain a casting solution;

[0111] The casting solution is prepared by a step-by-step dissolution method, which specifically comprises the following steps:

[0112] Step S1, dissolving polyether sulfone in part of N-methyl pyrrolidone to form a base solution;

[0113] Step S2, ultrasonic dispersion of the zwitterionic block copolymer and Tz-GQDs in the remaining N-methyl pyrrolidone, and addition of 0.5wt% silane coupling agent KH-550 to obtain a premix;

[0114] Step S3, adding the premix to the base solution, and then adding a tetrabutyl titanate solution containing 0.3wt% acetylacetone after stirring at 60°C for 4 hours. TiO2 inorganic crosslinking points are formed through chelation of tetrabutyl titanate in acetylacetone, so that the tensile strength is improved.

[0115] The particle size of the tetrazine modified graphene quantum dots is 5nm, and the density of tetrazine groups is ≥8 / quantum dot. The embedding of tetrazine modified graphene quantum dots in the polymer network enhances the screening precision and improves the divalent salt retention rate; the gradient pH mineralization precisely controls the whisker orientation to avoid pore blockage.

[0116] The zwitterionic block copolymer forms a dynamic hydration layer through strong hydration to inhibit the adsorption of pollutants.

[0117] Dissolve calcium chloride and disodium hydrogen phosphate in deionized water, adjust the pH value of the solution to 8.0 by adding triethanolamine, and continuously stir, and add norbornene modified chitosan during stirring to obtain a coagulation bath;

[0118] Step A2, preparation of biomimetic mineralization film forming; the casting solution is scraped into a film, immersed in the coagulation bath, and the pH value is controlled at 8.2 to induce the formation of a hydroxyapatite whisker layer on the surface of the film; the vertical array of hydroxyapatite whiskers formed by biomimetic mineralization provides a super-hydrophilic surface to reduce the adhesion of organic matter;

[0119] The hydroxyapatite whisker layer is arranged in a vertical array, with a length of 400nm and a coverage density of 24 roots / μm 2The vertical arrangement of hydroxyapatite whiskers can reduce the water transport resistance and increase the flux by more than 40%.

[0120] Step A3, near-infrared light dynamic crosslinking; the wet film is placed in a solution containing norbornene-modified chitosan, and near-infrared light with a wavelength of 825 nm and a power density of 1 W / cm 2 The film surface has self-repairing ability, which can repair the damage.

[0121] Gradient pH mineralization: maintain pH 9.0 for the first 2 minutes, then decrease to pH 7.0 at a rate of 0.5 pH / min and maintain for 10 minutes.

[0122] Step A4, post-curing treatment; heat treatment at 80°C for 40 minutes to complete the oxidation crosslinking of catechol, and obtain a modified polyether sulfone nanofiltration membrane; the oxidation crosslinking of catechol can resist extreme environments with pH 2-12; the light-triggered iEDDA reaction can anchor norbornene-modified chitosan on the membrane surface to resist water shear peeling.

[0123] Non-contact precise curing is realized by near-infrared light dynamic crosslinking, which can reduce energy consumption by 50%; step-by-step dissolution method combined with KH-550 silane coupling agent ensures uniform dispersion of Tz-GQDs; the coagulation bath of triethanolamine / dibasic sodium phosphate buffer system maintains the stability of mineralization pH and reduces structural defects.

[0124] Tetrazine-GQDs have functions of light-heat conversion (near-infrared absorption rate > 90%) and crosslinking site; norbornene-modified chitosan has the dual roles of regulating phase separation rate and photocrosslinking monomer; the optimized block copolymer molar ratio of 3.5:1 balances hydrophilicity / adhesion, and strengthens the synergistic effect of antifouling and interface combination.

[0125] It should be noted that, in this text, relational terms such as first and second are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or equipment. Without more limitations, the element defined by the statement "including a..." does not exclude the presence of other identical elements in the process, method, article or equipment including the element.

[0126] While embodiments of the application have been shown and described, it is to be understood that the embodiments described are merely exemplary of the principles and application of the present application. Numerous modifications and adaptions can be effected without departing from the spirit and scope of the present application, which is not limited to the exact construction and arrangement described. It is intended, therefore, to cover all modifications and adaptions that fall within the scope of the claims and their equivalents.

Claims

1. A pollution-resistant modified polyethersulfone nanofiltration membrane, characterized in that: Includes the following components: Casting solution components: 80-120 parts by mass of polyethersulfone, 30-50 parts by mass of zwitterionic block copolymer, 2-5 parts by mass of tetrazine-modified graphene quantum dots, 6-18 parts by mass of tetrabutyl titanate, and 480-550 parts by mass of N-methylpyrrolidone; Coagulation bath components: 300-320 parts by mass of deionized water, 5.5-8.5 parts by mass of calcium chloride, 4.0-6.5 parts by mass of disodium hydrogen phosphate, 3-8 parts by mass of norbornene-modified chitosan, and 1.2-2 parts by mass of triethanolamine.

2. The anti-pollution modified polyethersulfone nanofiltration membrane according to claim 1, characterized in that: Includes the following components: Casting solution components: 100 parts by mass of polyethersulfone, 40 parts by mass of zwitterionic block copolymer, 3.5 parts by mass of tetrazine-modified graphene quantum dots, 12 parts by mass of tetrabutyl titanate, and 500 parts by mass of N-methylpyrrolidone; Coagulation bath components: 310 parts by mass of deionized water, 7 parts by mass of calcium chloride, 5 parts by mass of disodium hydrogen phosphate, 5.5 parts by mass of norbornene-modified chitosan, and 1.6 parts by mass of triethanolamine.

3. The anti-pollution modified polyethersulfone nanofiltration membrane according to claim 2, characterized in that: The zwitterionic block copolymer is specifically polysulfobetaine-b-polydopamine acrylamide, and its block molar ratio is (3-4):

1.

4. A method for preparing a pollution-resistant modified polyethersulfone nanofiltration membrane, characterized in that: The following steps are involved: Step A1: Preparation of casting solution and coagulation bath: Dissolving polyethersulfone, zwitterionic block copolymer, tetrazine-modified graphene quantum dots and tetrabutyl titanate in N-methylpyrrolidone to obtain a casting solution; Calcium chloride and disodium hydrogen phosphate were dissolved in deionized water, triethanolamine was added to adjust the pH value of the solution to 8.0-9.0, and stirring was continued. Norbornene-modified chitosan was added during stirring to obtain a coagulation bath; Step A2, preparing a biomimetic mineralized film; scraping the casting solution into a film, immersing it in a coagulation bath, controlling the pH value at 7.0-9.0, and inducing the formation of a hydroxyapatite whisker layer on the film surface; Step A3, near-infrared dynamic crosslinking: the wet film is placed in a solution containing norbornene-modified chitosan, using a wavelength of 800-850nm and a power density of 0.5-1.5W / cm 2 Irradiation with near-infrared light triggers the reverse electron demand Diels-Alder reaction between the tetrazine group and the norbornene group; Step A4, post-curing treatment: heat treatment at 60-80° C. for 20-40 minutes to complete the oxidative cross-linking of catechol to obtain a modified polyethersulfone nanofiltration membrane.

5. The method for preparing a pollution-resistant modified polyethersulfone nanofiltration membrane according to claim 4, characterized in that: The casting solution in step A1 is prepared by a step-by-step dissolution method, which specifically includes the following steps: Step S1, dissolving polyethersulfone in a portion of N-methylpyrrolidone to form a base liquid; Step S2, ultrasonically dispersing the zwitterionic block copolymer and Tz-GQDs in the remaining N-methylpyrrolidone, and adding 0.1-0.5 wt % of silane coupling agent KH-550 to obtain a premixed solution; Step S3: Add the premixed liquid to the base liquid, stir at 50-60° C. for 2-4 hours, and then add a tetrabutyl titanate solution containing 0.1-0.3 wt % of acetylacetone.

6. The method for preparing a pollution-resistant modified polyethersulfone nanofiltration membrane according to claim 5, characterized in that: In the step A1, the particle size of the tetrazine-modified graphene quantum dots is 3-5 nm, and the tetrazine group density is ≥8 per quantum dot.

7. The method for preparing an anti-pollution modified polyethersulfone nanofiltration membrane according to claim 4, characterized in that: In step A2, gradient pH mineralization is adopted, and the specific steps are as follows: The pH was maintained at 9.0 for the first 1-3 minutes, then decreased to pH 7.0-7.5 at a rate of 0.5 pH / min and maintained there for 5-10 minutes.

8. The method for preparing a pollution-resistant modified polyethersulfone nanofiltration membrane according to claim 4, characterized in that: In step A2, the hydroxyapatite whisker layer is arranged in a vertical array, has a length of 100-500 nm, and a coverage density of 10-30 whiskers / μm. 2 .