A high-throughput anti-pollution reverse osmosis membrane and its preparation method

Abstract

The present invention discloses a high-throughput anti-pollution reverse osmosis membrane and a preparation method thereof, which relates to the technical field of reverse osmosis membrane preparation. In the present invention, diamine monomers, diacyl chloride monomers and zinc acetate are used as raw materials, and a flat fiber membrane containing ZnO is prepared by electrospinning technology. Then, the surface of the flat fiber membrane is modified, and finally MXene nanosheets are loaded on the surface of the flat fiber membrane; the surface modification enables the flat fiber membrane to have good hydrophilicity, improves the water flux rate, prevents pollutants from directly contacting the surface of the flat fiber membrane, reduces pollutant adsorption, and improves the anti-pollution performance of the flat fiber membrane; ZnO and MXene nanosheets act synergistically to expand the layer spacing through steric hindrance effects, jointly regulate ion hydration, optimize the transmission path of water molecules, enhance the selective rejection of salt ions, and improve the desalination rate.

Description

Technical Field

[0001] The present invention relates to the technical field of reverse osmosis membrane preparation, and specifically to a high-flux anti-fouling reverse osmosis membrane and a preparation method thereof. Background Technique

[0002] As the core of reverse osmosis technology, reverse osmosis membranes play an important role in water treatment technology. Their working principle is to make water molecules in sewage permeate against the concentration gradient by applying pressure, so as to achieve the effect of intercepting pollutants such as dissolved salts, organic matters, and microorganisms. Reverse osmosis technology originated from the research on seawater desalination in the 1950s and has gradually expanded to fields such as high-salt industrial wastewater treatment and municipal sewage reuse. In the prior art, there are mainly two types of reverse osmosis membranes, namely cellulose acetate membranes and polyamide composite membranes. Among them, cellulose acetate membranes are less used due to poor heat resistance and high operating pressure, while polyamide composite membranes have good thermal stability and mechanical stability and are widely used.

[0003] Traditional polyamide composite membranes have three layers, namely a non-woven fabric layer, a polysulfone porous layer, and a polyamide functional layer. Patent CN202210687721.9 discloses a high-flux antibacterial reverse osmosis membrane and its preparation method and application. The obtained reverse osmosis membrane has a multi-layer structure, and the connection between layers is tight, which prolongs the service life of the reverse osmosis membrane, but the production cost is high and the preparation process is complex.

[0004] Therefore, we propose a high-flux anti-fouling reverse osmosis membrane and a preparation method thereof. Summary of the Invention

[0005] The purpose of the present invention is to provide a high-flux anti-fouling reverse osmosis membrane and a preparation method thereof to solve the problems raised in the prior art.

[0006] To achieve the above purpose, the present invention provides the following technical solution: A preparation method of a high-flux anti-fouling reverse osmosis membrane, comprising the following steps:

[0007] Step (1): Pour a hexitol solution on the surface of a polyamide flat fiber membrane, react for 5-15 minutes, pour off the excess solution, rinse the surface of the fiber membrane, then pour a hydroxypropyl-β-cyclodextrin solution, react for 5-15 minutes, pour off the excess solution, and rinse the surface of the fiber membrane to obtain a modified polyamide flat fiber membrane;

[0008] Step (2): Load the MXene nanosheet dispersion on the modified polyamide flat fiber membrane by vacuum filtration, and dry to obtain a reverse osmosis membrane.

[0009] Further, in step (1), the preparation process of the hexitol solution is as follows:

[0010] Mix triethylamine and deionized water in a mass ratio of 1:90, stir evenly to obtain a mixed solution, and then add hexaglycerol to obtain a hexaglycerol solution.

[0011] Furthermore, the mass ratio of the mixed solution to hexaglycerol is 1:0.1.

[0012] Furthermore, in step (1), the preparation process of the hydroxypropyl-β-cyclodextrin solution is as follows:

[0013] Mix hydroxypropyl-β-cyclodextrin and deionized water in a mass ratio of 1:90, stir evenly to obtain a hydroxypropyl-β-cyclodextrin solution.

[0014] Furthermore, the mass ratio of the polyamide flat fiber membrane, the hexaglycerol solution, and the hydroxypropyl-β-cyclodextrin solution is 1:(1 - 3):(1 - 3).

[0015] Furthermore, in step (2), the mass ratio of the MXene nanosheet dispersion to the modified polyamide flat fiber membrane is 10:(3 - 8).

[0016] Furthermore, in step (2), the drying process conditions are: temperature 45 - 65°C, time 25 - 45 min.

[0017] In the above technical solution, through the reaction of the hydroxyl groups of hexaglycerol with the acyl chloride groups of the polyamide flat fiber membrane, hexaglycerol is grafted onto the surface of the polyamide flat fiber membrane. Multiple hydroxyl groups in hexaglycerol form hydrogen bonds with water molecules, promoting water molecule transfer. At the same time, a hydration layer is formed to prevent direct contact between pollutants and the fiber membrane surface, reducing pollutant adsorption and improving the anti-fouling performance of the fiber membrane. Moreover, hexaglycerol has good hydrophilicity, which can improve water permeability; through the interfacial polymerization reaction of the hydroxyl groups of hydroxypropyl-β-cyclodextrin with the remaining acyl chloride groups, a polyester protective layer is constructed on the surface of the fiber membrane, reducing the surface roughness of the fiber membrane, increasing its hydrophilicity, and also endowing the fiber membrane with good high-temperature resistance, reducing the flux decay caused by membrane fouling, and extending its service life.

[0018] Furthermore, in step (1), the polyamide flat fiber membrane is prepared by the following process:

[0019] Mix a diamine monomer, a diacyl chloride monomer, zinc acetate, and a solvent, stir and react under a nitrogen atmosphere protection to obtain a spinning solution, then transfer it to a syringe and perform electrospinning on an injection pump to obtain a flat membrane. Heat-treat the flat membrane, then place it in a growth solution and heat-react, take it out to obtain a polyamide flat fiber membrane.

[0020] Furthermore, the mass ratio of the diamine monomer, the diacyl chloride monomer, zinc acetate to the solvent is 1:1:(3 - 5):(6 - 10).

[0021] Further, the process conditions for the stirring reaction are as follows: temperature 0 - 20°C, time 1 - 3 h, rotation speed 80 - 90 r / min.

[0022] Further, the viscosity of the spinning solution is 1 - 20 Pa·s.

[0023] Further, the process conditions for electrospinning are as follows: voltage 10 - 18 kV, feeding rate 0.5 - 0.7 mL / h, distance between the syringe tip and the collector 10 - 16 cm, humidity 10 - 30%, time 1.5 - 2 h.

[0024] Further, the process conditions for heat treatment are as follows: temperature 100 - 130°C, time 8 - 10 h.

[0025] Further, the process conditions for the heating reaction are as follows: temperature 80 - 100°C, time 6 - 10 h.

[0026] Further, the diamine monomer is one or a mixture of more than one of m - phenylenediamine, hexamethylenediamine, 1,4 - butanediamine, dodecanediamine, tetramethylhexamethylenediamine, and p - phenylenediamine.

[0027] Further, the diacyl chloride monomer is one or a mixture of more than one of adipoyl chloride, sebacoyl chloride, dodecanedioyl chloride, terephthaloyl chloride, isophthaloyl chloride, 2,6 - naphthalenedicarbonyl chloride, and 1,4 - cyclohexanedicarbonyl chloride.

[0028] Further, the solvent is a mixed solution obtained by mixing a polar aprotic organic solvent and an inorganic salt co - solvent in a mass ratio of 1:(1 - 9).

[0029] Further, the polar aprotic organic solvent is one or a mixture of more than one of DMF (N,N - dimethylformamide), DMSO (dimethyl sulfoxide), DMAc (N,N - dimethylacetamide), and NMP (N - methylpyrrolidone);

[0030] The inorganic salt co - solvent is one or a mixture of more than one of CaCl2 (calcium chloride), LiBr (lithium bromide), and LiCl (lithium chloride).

[0031] Further, the growth solution is a mixed solution obtained by mixing zinc nitrate and a 0.1 mol / L aqueous solution of hexamethylenetetramine in a mass ratio of 1:1.

[0032] Further, in step (2), the MXene nanosheet dispersion is prepared by the following process:

[0033] S1: Mix Ti3AlC2 (titanium aluminum carbide), LiF (lithium fluoride) and hydrochloric acid solution, stir and react, conduct the first centrifugation, wash, mix the centrifuged precipitate with pure water, under the protection of nitrogen atmosphere, conduct ultrasonic treatment, conduct the second centrifugation, and freeze-dry the supernatant after centrifugation to obtain MXene nanosheets;

[0034] S2: Mix MXene nanosheets and buffer solution, conduct ultrasonic dispersion to obtain MXene nanosheet dispersion.

[0035] Further, in S1, the ratio of Ti3AlC2, LiF to hydrochloric acid solution is (2 - 4) g : (3 - 5) g : (100 - 200) mL;

[0036] The mass ratio of the precipitate to pure water is 1 : (10 - 20).

[0037] Further, the mass fraction of the hydrochloric acid solution is 36%.

[0038] Further, in S1, the instrument model used for ultrasonic treatment is LD-CP650, and the process conditions for ultrasonic treatment are: power 300 - 500 W, time 4 - 6 h.

[0039] Further, in S1, the process conditions for the first centrifugation are: rotation speed 3000 - 5000 rpm, time 4 - 6 min;

[0040] The process conditions for the second centrifugation are: rotation speed 8000 - 10000 rpm, time 20 - 30 min.

[0041] Further, in S1, the process conditions for freeze-drying are: temperature -20 - -10 °C, time 36 - 48 h.

[0042] Further, in S2, the mass ratio of MXene nanosheets to buffer solution is 1 : (10 - 20).

[0043] Further, the preparation method of the buffer solution is as follows:

[0044] Mix tris(hydroxymethyl)aminomethane hydrochloride and pure water in a ratio of 0.1 g : 50 mL, adjust the pH value to 8.5 to obtain the buffer solution.

[0045] In the above technical solution, using diamine monomer, diacyl chloride monomer and zinc acetate as raw materials, a nanofiber membrane containing ZnO was prepared by electrospinning technology. However, using ZnO as a raw material for spinning will cause uneven distribution and polymerization. Therefore, zinc acetate is used, and through heat treatment, ZnO seeds are formed. Hexamethylenetetramine in the growth solution is heated and hydrolyzed to release OH - , and zinc nitrate dissociates to provide Zn 2+, The two combine to generate Zn(OH)₂ intermediate, which then dehydrates to form ZnO nuclei. The ZnO seeds provide heterogeneous nucleation sites, reducing the nucleation energy barrier and promoting the growth of ZnO. ZnO can initiate redox reactions under ultraviolet irradiation to decompose organic pollutants in water. When combined with the fiber membrane, they act synergistically to further improve the filtration performance of the reverse osmosis membrane. At the same time, the polar surface of ZnO enhances the hydrophilicity of the fiber membrane, further increasing the water flux and reducing membrane fouling;

[0046] The MXene nanosheets have a hydrophilic surface and a high porosity. The MXene nanosheets are loaded on the fiber membrane through vacuum filtration technology, further enhancing the flux of the reverse osmosis membrane. The conductive network of the MXene nanosheets can rapidly move charges, reducing fouling caused by charge accumulation on the membrane surface;

[0047] In addition, ZnO and MXene nanosheets act synergistically to expand the interlayer spacing through steric hindrance effects, jointly regulate ion hydration, optimize the transport path of water molecules, enhance the selective rejection of salt ions, and improve the desalination rate.

[0048] Compared with the prior art, the beneficial effects of the present invention are:

[0049] 1. By reacting the hydroxyl groups of hexitol with the acyl chloride groups of the polyamide flat fiber membrane, hexitol is grafted onto the surface of the polyamide flat fiber membrane. Multiple hydroxyl groups in hexitol form hydrogen bonds with water molecules, promoting water molecule transfer. At the same time, a hydration layer is formed to prevent pollutants from directly contacting the fiber membrane surface, reducing pollutant adsorption and improving the anti-fouling performance of the fiber membrane. Moreover, hexitol has good hydrophilicity, which can improve water permeability. Through the interfacial polymerization reaction of the hydroxyl groups of hydroxypropyl-β-cyclodextrin with the remaining acyl chloride groups, a polyester protective layer is constructed on the surface of the fiber membrane, reducing the surface roughness of the fiber membrane, increasing its hydrophilicity, and also endowing the fiber membrane with good high-temperature resistance, reducing the flux decay caused by fouling, and extending its service life.

[0050] 2. Using diamine monomers, diacyl chloride monomers, and zinc acetate as raw materials, a nanofiber membrane containing ZnO is prepared through electrospinning technology. However, using ZnO as a raw material for spinning will result in uneven distribution and polymerization. Therefore, zinc acetate is used, and then through heat treatment, ZnO seeds are formed. Hexamethylenetetramine in the growth solution is heated and hydrolyzed to release OH - , and zinc nitrate dissociates to provide Zn 2+, The two combine to generate Zn(OH)₂ intermediate, which then dehydrates to form ZnO nuclei. The ZnO seeds provide heterogeneous nucleation sites, reduce the nucleation energy barrier, and promote the growth of ZnO. ZnO can trigger redox reactions under ultraviolet irradiation to decompose organic pollutants in water. Combined with the fiber membrane, they work synergistically to further improve the filtration performance of the reverse osmosis membrane. At the same time, the polar surface of ZnO enhances the hydrophilicity of the fiber membrane, further increasing the water flux and reducing membrane fouling;

[0051] The surface of MXene nanosheets is hydrophilic and has a high porosity. The MXene nanosheets are loaded on the fiber membrane through vacuum filtration technology, further enhancing the flux of the reverse osmosis membrane. The conductive network of MXene nanosheets can rapidly move charges, reducing the fouling caused by charge accumulation on the membrane surface;

[0052] In addition, ZnO and MXene nanosheets work synergistically to expand the layer spacing through steric hindrance effects, jointly regulate ion hydration, optimize the transport path of water molecules, enhance the selective rejection of salt ions, and improve the desalination rate. Detailed implementation manners

[0053] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0054] In the following detailed implementation manners,

[0055] Triethylamine, with a CAS number of 121-44-8, is sourced from Nanjing Reagent;

[0056] Hexaerythritol, with a CAS number of 69-65-8, is sourced from Merck Reagent;

[0057] Hydroxypropyl-β-cyclodextrin, with a CAS number of 94035-02-6, is sourced from Wuhan Lanabai Pharmaceutical and Chemical Co., Ltd.;

[0058] Zinc acetate, with a CAS number of 557-34-6, is sourced from Hubei Xinghengye Technology Co., Ltd.;

[0059] m-Phenylenediamine, with a CAS number of 108-45-2, is sourced from Merck Reagent;

[0060] Isophthaloyl chloride, with a CAS number of 99-63-8, is sourced from Shanghai Yuanye Bio-Technology Co., Ltd.;

[0061] Zinc nitrate, with a CAS number of 13778-30-8, is sourced from Merck Reagent;

[0062] Hexamethylenetetramine, with a CAS number of 100-97-0, sourced from Nanjing Reagent;

[0063] DMF, with a CAS number of 127-19-5, sourced from Merck Reagents;

[0064] LiBr, with a CAS number of 7550-35-8, sourced from Hubei Shiteng Chemical Technology Co., Ltd.;

[0065] Tris(hydroxymethyl)aminomethane hydrochloride, with a CAS number of 1185-53-1, sourced from Wuhan Desheng Biochemical Technology Co., Ltd.;

[0066] Ti3AlC2, with a CAS number of 12537-81-4, 500 mesh, sourced from Ningbo Beijiaer New Materials Co., Ltd.;

[0067] LiF, with a CAS number of 7789-24-4, sourced from Shandong Duolian Chemical Co., Ltd.;

[0068] Hydrochloric acid solution, with a CAS number of 7647-01-0, mass fraction 36%, sourced from Nanjing Reagent;

[0069] NaCl, with a CAS number of 7647-14-5, sourced from Langfang Pengcai Fine Chemical Co., Ltd.;

[0070] Bovine serum albumin: CAS number 9048-46-8, sourced from Shanghai Jizhi Biochemical Technology Co., Ltd.;

[0071] Preparation of growth solution: Mix zinc nitrate and 0.1 mol / L hexamethylenetetramine aqueous solution in a mass ratio of 1:1 to obtain the growth solution;

[0072] Preparation of buffer solution: Mix tris(hydroxymethyl)aminomethane hydrochloride and pure water in a ratio of 0.1 g:50 mL, and adjust the pH value to 8.5 to obtain the buffer solution;

[0073] Preparation of hexitol solution: Mix triethylamine and deionized water in a mass ratio of 1:90, stir evenly to obtain a mixed solution, and then add hexitol to obtain the hexitol solution; the mass ratio of the mixed solution to hexitol is 1:0.1;

[0074] Preparation of hydroxypropyl-β-cyclodextrin solution: Mix hydroxypropyl-β-cyclodextrin and deionized water in a mass ratio of 1:90, stir evenly to obtain the hydroxypropyl-β-cyclodextrin solution.

[0075] Example 1: A method for preparing a high-throughput anti-fouling reverse osmosis membrane, comprising the following steps:

[0076] (1) Preparation of polyamide flat fiber membrane:

[0077] Mix DMF and LiBr in a mass ratio of 1:9, stir evenly to obtain a solvent;

[0078] Mix m-phenylenediamine, isophthaloyl chloride, zinc acetate and the solvent in a mass ratio of 1:1:5:10. Under the protection of a nitrogen atmosphere, at 0 °C, stir and react at a speed of 90 r / min for 3 h to obtain a spinning solution. Then transfer it to a syringe and perform electrospinning on an injection pump to obtain a flat membrane. Heat-treat the flat membrane, and then place it in a growth solution and heat it to 100 °C for 10 h, take it out to obtain a polyamide flat fiber membrane; The process conditions for electrospinning are: voltage 18 kV, feeding speed 0.7 mL / h, distance between the syringe needle tip and the collector 16 cm, humidity 30%, time 2 h; The process conditions for heat treatment are: temperature 130 °C, time 10 h; The viscosity of the spinning solution is 1 Pa·s;

[0079] (2)Preparation of MXene nanosheet dispersion:

[0080] S1: Mix Ti3AlC2, LiF and hydrochloric acid solution in a ratio of 4 g:5 g:200 mL, stir and react, perform the first centrifugation and washing. Mix the centrifuged precipitate with pure water in a mass ratio of 1:20. Under the protection of a nitrogen atmosphere, ultrasonicate for 6 h, perform the second centrifugation, and freeze-dry the upper layer of the centrifuged solution at -20 °C for 48 h to obtain MXene nanosheets; S2: Mix MXene nanosheets and buffer solution in a mass ratio of 1:20, and ultrasonically disperse to obtain MXene nanosheet dispersion; In S1, the process conditions for the first centrifugation are: rotation speed 5000 rpm, time 6 min; The process conditions for the second centrifugation are: rotation speed 10000 rpm, time 30 min. In S1, the process conditions for ultrasonication are: power 500 W, time 6 h;

[0081] (3)Preparation of reverse osmosis membrane:

[0082] Step (1): Pour hexanetriol solution on the surface of the polyamide flat fiber membrane, react for 15 minutes, pour off the excess solution, rinse the surface of the fiber membrane, then pour hydroxypropyl-β-cyclodextrin solution, react for 15 minutes, pour off the excess solution, and rinse the surface of the fiber membrane to obtain a modified polyamide flat fiber membrane; Step (2): Load the MXene nanosheet dispersion onto the modified polyamide flat fiber membrane by vacuum filtration, and dry to obtain a reverse osmosis membrane; In step (1), the mass ratio of the polyamide flat fiber membrane, hexanetriol solution and hydroxypropyl-β-cyclodextrin solution is 1:3:3; In step (2), the mass ratio of the MXene nanosheet dispersion to the modified polyamide flat fiber membrane is 10:8; In step (2), the process conditions for drying are: temperature 65 °C, time 45 min.

[0083] Example 2: A method for preparing a high-throughput anti-pollution reverse osmosis membrane, comprising the following steps:

[0084] (1) Preparation of a polyamide flat fiber membrane:

[0085] Mix DMF and LiBr in a mass ratio of 1:5, stir evenly to obtain a solvent;

[0086] Mix m-phenylenediamine, isophthaloyl chloride, zinc acetate and the solvent in a mass ratio of 1:1:4:8. Under the protection of a nitrogen atmosphere, at 10 °C, stir and react at a speed of 85 r / min for 2 h to obtain a spinning solution. Then transfer it to a syringe and perform electrospinning on an injection pump to obtain a flat membrane. Heat-treat the flat membrane, and then place it in a growth solution and heat it to 90 °C for 8 h, take it out to obtain a polyamide flat fiber membrane; The process conditions for electrospinning are: voltage 15 kV, feeding speed 0.6 mL / h, distance between the syringe needle tip and the collector 13 cm, humidity 20%, time 1.7 h; The process conditions for heat treatment are: temperature 120 °C, time 9 h; The viscosity of the spinning solution is 10 Pa·s;

[0087] (2) Preparation of an MXene nanosheet dispersion:

[0088] S1: Mix Ti3AlC2, LiF and hydrochloric acid solution in a ratio of 3 g:4 g:150 mL, stir and react, perform the first centrifugation and washing. Mix the centrifuged precipitate with pure water in a mass ratio of 1:15. Under the protection of a nitrogen atmosphere, ultrasonicate for 5 h, perform the second centrifugation, and freeze-dry the upper layer of the centrifuged solution at -15 °C for 42 h to obtain MXene nanosheets; S2: Mix the MXene nanosheets and the buffer solution in a mass ratio of 1:15 and ultrasonically disperse to obtain an MXene nanosheet dispersion; In S1, the process conditions for the first centrifugation are: rotation speed 4000 rpm, time 5 min; The process conditions for the second centrifugation are: rotation speed 9000 rpm, time 25 min. In S1, the process conditions for ultrasonication are: power 400 W, time 5 h;

[0089] (3) Preparation of a reverse osmosis membrane:

[0090] Step (1): Pour the hexanetriol solution onto the surface of the polyamide flat fiber membrane, react for 10 minutes, pour off the excess solution, rinse the surface of the fiber membrane, then pour the hydroxypropyl-β-cyclodextrin solution, react for 10 minutes, pour off the excess solution, and rinse the surface of the fiber membrane to obtain a modified polyamide flat fiber membrane; Step (2): Load the MXene nanosheet dispersion onto the modified polyamide flat fiber membrane by vacuum filtration, and dry to obtain a reverse osmosis membrane; in Step (1), the mass ratio of the polyamide flat fiber membrane, hexanetriol solution and hydroxypropyl-β-cyclodextrin solution is 1:2:2; in Step (2), the mass ratio of the MXene nanosheet dispersion to the modified polyamide flat fiber membrane is 10:5; in Step (2), the drying process conditions are: temperature 55°C, time 35 min.

[0091] Example 3: A preparation method of a high-flux anti-fouling reverse osmosis membrane, comprising the following steps:

[0092] (1) Preparation of the polyamide flat fiber membrane:

[0093] Mix DMF and LiBr in a mass ratio of 1:1, stir evenly to obtain a solvent;

[0094] Mix m-phenylenediamine, m-phthaloyl chloride, zinc acetate and the solvent in a mass ratio of 1:1:3:6, under the protection of a nitrogen atmosphere, at 20°C, stir and react at a rotation speed of 80 r / min for 1 h to obtain a spinning solution, then transfer it to a syringe, and perform electrospinning on an injection pump to obtain a flat membrane. Heat-treat the flat membrane, then place it in a growth solution and heat it to 80°C for 6 h, take it out to obtain a polyamide flat fiber membrane; the process conditions for electrospinning are: voltage 10 kV, feeding speed 0.5 mL / h, distance between the syringe needle tip and the collector 10 cm, humidity 10%, time 1.5 h; the process conditions for heat treatment are: temperature 100°C, time 8 h; the viscosity of the spinning solution is 20 Pa·s;

[0095] (2) Preparation of the MXene nanosheet dispersion:

[0096] S1: Mix Ti3AlC2, LiF, and hydrochloric acid solution in the ratio of 2 g: 3 g: 100 mL, stir and react, conduct the first centrifugation, wash, mix the centrifuged precipitate with pure water in a mass ratio of 1:10, under the protection of nitrogen atmosphere, ultrasonicate for 4 h, conduct the second centrifugation, and freeze-dry the supernatant after centrifugation at -10 °C for 36 h to obtain MXene nanosheets; S2: Mix MXene nanosheets and buffer solution in a mass ratio of 1:10, ultrasonically disperse to obtain an MXene nanosheet dispersion; In S1, the process conditions for the first centrifugation are: rotation speed 3000 rpm, time 4 min; the process conditions for the second centrifugation are: rotation speed 8000 rpm, time 20 min. In S1, the process conditions for ultrasonication are: power 300 W, time 4 h;

[0097] (3) Preparation of the reverse osmosis membrane:

[0098] Step (1): Pour hexanetriol solution onto the surface of the polyamide flat fiber membrane, react for 5 minutes, pour off the excess solution, rinse the surface of the fiber membrane, then pour hydroxypropyl-β-cyclodextrin solution, react for 5 minutes, pour off the excess solution, and rinse the surface of the fiber membrane to obtain a modified polyamide flat fiber membrane; Step (2): Load the MXene nanosheet dispersion onto the modified polyamide flat fiber membrane by vacuum filtration, and dry to obtain the reverse osmosis membrane; In step (1), the mass ratio of the polyamide flat fiber membrane, hexanetriol solution, and hydroxypropyl-β-cyclodextrin solution is 1:1:1; In step (2), the mass ratio of the MXene nanosheet dispersion to the modified polyamide flat fiber membrane is 10:3; In step (2), the process conditions for drying are: temperature 45 °C, time 25 min.

[0099] Comparative Example 1: Compared with Example 1, the polyamide flat fiber membrane is not graft-modified with hexanetriol and hydroxypropyl-β-cyclodextrin, and the other conditions remain unchanged.

[0100] Comparative Example 2: Compared with Example 1, zinc acetate is not added during the preparation of the polyamide flat fiber membrane, and MXene nanosheets are not loaded on the modified polyamide flat fiber membrane, and the other conditions remain unchanged.

[0101] Comparative Example 3: Compared with Example 1, the polyamide flat fiber membrane is not graft-modified with hexanetriol and hydroxypropyl-β-cyclodextrin, and at the same time, MXene nanosheets are not loaded on the modified polyamide flat fiber membrane, and the other conditions remain unchanged.

[0102] Experiment: Take the reverse osmosis membranes obtained in Examples 1 to 3 and Comparative Examples 1 to 3, and conduct various performance tests on them;

[0103] Prepare a 2000 mg / L NaCl aqueous solution as the feed solution, and use a cross-flow reverse osmosis membrane evaluation device (the effective area of the membrane cell is 29.2 cm2 ), at 2.5 MPa and 60 °C, the water flux (J w ) and salt rejection rate (R) of the reverse osmosis membrane were tested;

[0104] ;

[0105] ;

[0106] J w —— water flux, L / (m 2 ·h);

[0107] V —— volume of permeate, L;

[0108] M —— effective area of the membrane, m 2 ;

[0109] t —— permeate collection time, h;

[0110] C p —— mass concentration of NaCl in the permeate;

[0111] C f —— mass concentration of NaCl in the feed solution.

[0112] Using an aqueous NaCl solution of 2000 mg / L, the reverse osmosis membrane was pre-pressed at 2.5 MPa for 20 min, and the initial water flux J0 was tested. Bovine serum albumin (300 mg / L) was added to the aqueous NaCl solution, and it was operated at 2.5 MPa for 300 min. The water flux J t was tested every 30 min, and then the reverse osmosis membrane was cleaned, and the water flux J wc after cleaning was tested. The operating conditions were the same as the initial ones, and the membrane flux decline rate (FDR) was calculated;

[0113] ;

[0114] The following table shows the test results of each performance of the reverse osmosis membrane;

[0115]

[0116] According to the data in the above table, the following conclusions can be obtained:

[0117] By comparing the reverse osmosis membranes obtained in Examples 1 - 3 with those in Comparative Examples 1 - 3, the test results show that

[0118] Compared with Example 1, in Comparative Example 1, hexanehexol and hydroxypropyl-β-cyclodextrin were not used for graft modification of the polyamide flat fiber membrane, and its water flux decreased significantly, and the flux decay rate increased. The reason is that the surface of the fiber membrane formed by electrospinning is hydrophobic, while both hexanehexol and hydroxypropyl-β-cyclodextrin are hydrophilic and can improve water permeability. Hexanehexol can form a hydration layer on the surface of the fiber membrane to prevent pollutants from directly contacting the surface of the fiber membrane. Hydroxypropyl-β-cyclodextrin undergoes an interfacial polymerization reaction with acyl chloride groups to construct a polyester protective layer on the surface of the fiber membrane, reduce pollutant adsorption, and improve the anti-fouling performance of the fiber membrane;

[0119] Compared with Example 1, in Comparative Example 2, zinc acetate was not added during the preparation of the polyamide flat fiber membrane, and MXene nanosheets were not loaded on the modified polyamide flat fiber membrane, and the desalination rate decreased significantly. The reason is that zinc acetate forms ZnO under the action of heat treatment and growth solution, combines with MXene nanosheets, expands the layer spacing through steric hindrance effect, jointly regulates ion hydration, optimizes the transmission path of water molecules, enhances the selective rejection of salt ions, and improves the desalination rate;

[0120] Compared with Example 1, in Comparative Example 3, hexanehexol and hydroxypropyl-β-cyclodextrin were not used for graft modification of the polyamide flat fiber membrane, and at the same time, MXene nanosheets were not loaded on the modified polyamide flat fiber membrane. Both the water flux and the desalination rate decreased, and the flux decay rate increased. It can be seen that the process and the materials used in this application can promote the improvement of the water flux and desalination rate of the prepared reverse osmosis membrane and reduce the flux decay rate.

[0121] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention.

Claims

1. A method for preparing a high-throughput anti-pollution reverse osmosis membrane, characterized in that: The following steps are involved: Step (1): pouring a hexadecene solution onto the surface of a polyamide flat fiber membrane, reacting for 5 to 15 minutes, pouring off the excess solution, washing the surface of the flat fiber membrane, and then pouring a hydroxypropyl-β-cyclodextrin solution onto the surface of a polyamide flat fiber membrane, reacting for 5 to 15 minutes, pouring off the excess solution, washing the surface of the flat fiber membrane, and obtaining a modified polyamide flat fiber membrane; Step (2): loading the MXene nanosheet dispersion onto the modified polyamide flat fiber membrane by vacuum filtration, and drying to obtain a reverse osmosis membrane; The polyamide flat fiber membrane is prepared by the following process: The diamine monomer, diacyl chloride monomer, zinc acetate and solvent are mixed, stirred and reacted under the protection of nitrogen atmosphere to obtain a spinning solution, which is then transferred to a syringe and electrospun on an injection pump to obtain a flat membrane. The flat membrane is heat-treated and then placed in a growth solution for heating reaction for 6 to 10 hours, and taken out to obtain a polyamide flat fiber membrane. The MXene nanosheet dispersion is prepared by the following process: S1: Ti3AlC2, LiF and hydrochloric acid solution are mixed, stirred for reaction, centrifuged for the first time, washed, the precipitate after centrifugation is mixed with pure water, ultrasonicated under nitrogen atmosphere protection, centrifuged for the second time, and the upper layer liquid after centrifugation is freeze-dried to obtain MXene nanosheets; S2: Mix MXene nanosheets and buffer solution, and disperse them by ultrasonic to obtain MXene nanosheet dispersion.

2. The method for preparing a high-throughput anti-pollution reverse osmosis membrane according to claim 1, characterized in that: In step (1), the mass ratio of the polyamide flat fiber membrane, the hexadecene solution and the hydroxypropyl-β-cyclodextrin solution is 1:(1-3):(1-3).

3. The method for preparing a high-throughput anti-pollution reverse osmosis membrane according to claim 2, characterized in that: The process conditions of electrospinning were: voltage 10-18 kV, feed rate 0.5-0.7 mL / h, syringe needle tip distance to collector 10-16 cm, humidity 10-30%, time 1.5-2 h; The viscosity of the spinning solution is 1~20Pa·s.

4. The method for preparing a high-throughput anti-pollution reverse osmosis membrane according to claim 3, characterized in that: In S1, the ratio of Ti3AlC2, LiF and hydrochloric acid solution is (2~4) g: (3~5) g: (100~200) mL; The mass ratio of precipitate to pure water is 1:(10~20).

5. The method for preparing a high-flux anti-pollution reverse osmosis membrane according to claim 4, characterized in that: The process conditions of the stirring reaction are: temperature 0~20℃, time 1~3h, and rotation speed 80~90r / min.

6. The method for preparing a high-flux anti-pollution reverse osmosis membrane according to claim 5, characterized in that: In S1, the process conditions of the first centrifugation are: speed 3000~5000rpm, time 4~6min; The process conditions for the second centrifugation are: rotation speed 8000~10000rpm, time 20~30min.

7. The method for preparing a high-flux anti-pollution reverse osmosis membrane according to claim 6, characterized in that: In step (2), the mass ratio of MXene nanosheet dispersion to modified polyamide flat fiber membrane is 10:(3-8).

8. A high-throughput anti-pollution reverse osmosis membrane, characterized in that: Prepared according to the preparation method according to any one of claims 1 to 7.

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