High-effect reverse osmosis membrane as well as preparation process and application thereof

Abstract

The invention relates to a high-effect reverse osmosis membrane as well as a preparation process and application thereof, and belongs to the technical field of water treatment. The preparation method comprises the following steps: soaking a base membrane in a water-phase solution, taking out the base membrane, drying the surface of the base membrane, coating the base membrane with an oil-phase solution for interfacial polymerization reaction, and curing to obtain the reverse osmosis membrane; and coating the surface of the reverse osmosis membrane with the modified liquid, and drying to obtain the high-efficiency reverse osmosis membrane. Wherein the formula of the modified liquid comprises the following components in parts by weight: 3 to 5 parts of polyvinyl alcohol, 1 to 3 parts of polyacrylic acid, 0.3 to 0.5 part of citric acid, 0.1 to 0.3 part of cocamidopropyl hydroxysulfobetaine, 0.05 to 0.1 part of modified carbon nitride quantum dot dispersion liquid and 60 to 80 parts of deionized water. The reverse osmosis membrane prepared by the invention has excellent water flux, salt rejection rate and stain-resistant and self-cleaning functions.

Description

Technical Field

[0001] This invention belongs to the field of water treatment technology, and relates to a high-efficiency reverse osmosis membrane, its preparation process, and its application. Background Technology

[0002] Reverse osmosis membrane technology, as a core technology for deep desalination and wastewater resource utilization, is widely used in seawater desalination, municipal wastewater regeneration, zero discharge of industrial wastewater, and high-quality reclaimed water production due to its high separation performance.

[0003] However, traditional reverse osmosis systems face severe challenges in terms of resource conservation and environmental protection during actual operation, and are gradually failing to meet the ever-increasing demands for energy conservation and emission reduction. The core problems are mainly reflected in the following aspects: First, membrane fouling is a prominent issue, limiting system recovery rates. During operation, pollutants such as organic matter, microorganisms, colloids, and inorganic salt scale in the water are irreversibly adsorbed and deposited on the membrane surface and within the membrane pores, leading to severe membrane fouling. Membrane fouling causes increased system operating pressure, decreased permeate flow, and reduced desalination rates, forcing frequent chemical cleaning and necessitating lower system recovery rates to control the fouling rate. This not only results in a significant waste of water resources but also increases the cost and difficulty of subsequent concentrate treatment. Second, to control membrane fouling, existing technologies heavily rely on the addition of chemical agents in the pretreatment stage, such as bactericides, scale inhibitors, and flocculants. The use of these chemical agents increases operating costs and may lead to more complex chemical compositions in the subsequent concentrate, generating potential secondary pollution and imposing new burdens on the environment. Furthermore, the increased transmembrane pressure due to membrane fouling directly translates into increased system energy consumption. Meanwhile, frequent chemical cleaning not only requires system shutdowns, affecting continuous and stable operation, but also incurs additional costs for cleaning agents, labor, and wastewater treatment. It may also cause irreversible damage to the membrane material itself, shortening membrane lifespan and further increasing the overall lifecycle operating costs.

[0004] Therefore, there is an urgent need to develop a high-efficiency reverse osmosis membrane with self-cleaning function and its preparation process. Summary of the Invention

[0005] The purpose of this invention is to provide a high-efficiency reverse osmosis membrane, its preparation process, and its application, which has the characteristic of self-cleaning.

[0006] The objective of this invention can be achieved through the following technical solutions: A method for preparing a high-efficiency reverse osmosis membrane, the specific steps of which are as follows: S1-1: Immerse the base membrane in an aqueous solution, remove it and allow it to dry slightly. Then coat the base membrane with an oil solution to carry out an interfacial polymerization reaction. After curing, a reverse osmosis membrane is obtained. S1-2: The modified liquid is applied to the surface of the reverse osmosis membrane and dried to obtain the high-efficiency reverse osmosis membrane; The modified liquid has the following formula by weight: 3-5 parts polyvinyl alcohol, 1-3 parts polyacrylic acid, 0.3-0.5 parts citric acid, 0.1-0.3 parts cocamidopropyl hydroxysulfonyl betaine, 0.05-0.1 parts modified carbon nitride quantum dot dispersion, and 60-80 parts deionized water.

[0007] As a preferred embodiment of the present invention, the preparation method of the modified carbon nitride quantum dot dispersion is as follows: Graphite-phase carbon nitride and sodium tripolyphosphate were mixed and dispersed in deionized water and ultrasonically mixed for 1-2 h. Then, the mixture was transferred to a reaction vessel and reacted at 180-200 °C for 6-8 h. After naturally cooling to room temperature, the mixture was centrifuged at 8000-10000 rpm for 15-20 min. The supernatant was dialyzed through a dialysis bag with a molecular weight of 1000 Da for 24-48 h to obtain the modified carbon nitride quantum dot dispersion.

[0008] As a preferred embodiment of the present invention, the graphitic carbon nitride and sodium tripolyphosphate are mixed at a mass ratio of 1:(3~5).

[0009] As a preferred embodiment of the present invention, the preparation method of the modified liquid is as follows: S4-1: Heat half the mass of deionized water to 80~90 ℃, add polyvinyl alcohol under stirring, and continue stirring for 30~60 min to obtain solution A; S4-2: Cool the solution A to 50~60 ℃, add polyacrylic acid and cocamidopropyl hydroxysulfonate betaine in sequence under stirring, stir for 30~60 min to obtain solution B; S4-3: Cool the solution B to below 35 °C, add the remaining deionized water, and add the modified carbon nitride quantum dot dispersion. Stir for 30-60 min, and finally add citric acid. Continue stirring for 5-10 min to obtain the modified solution.

[0010] As a preferred embodiment of the present invention, the aqueous solution is formulated as follows: by mass percentage, 0.5-5% polyfunctional amine, 0.1-2% surfactant, 3-10% polar solvent, and the balance being water. Wherein, the polyfunctional amine is one or more of m-phenylenediamine, p-phenylenediamine, ethylenediamine, propylenediamine, and butanediamine; the surfactant is one or more of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, and sodium dodecyl sulfonate; and the polar solvent is one or two of dimethyl sulfoxide and N-methylpyrrolidone.

[0011] As a preferred embodiment of the present invention, the oil phase solution is formulated as follows: 0.1-0.3% acyl halide and the balance being oil phase solvent, by mass percentage. The acyl halide includes one or more of pyromellitic chlorobenzene chloride, phthaloyl chloride, orthophthaloyl chloride, isophthaloyl chloride, biphenyl dimethyl chloride, and benzene disulfonyl chloride; the oil phase solvent includes one or more of n-hexane, Isopar G, and Isopar L.

[0012] As a preferred embodiment of the present invention, the contact time between the base film surface and the aqueous solution is 10-30 s; the contact time between the base film surface and the oil solution is 10-60 s.

[0013] As a preferred embodiment of the present invention, the material of the base film is selected from one of polysulfone, polyethersulfone, polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, polyimide, polyetherimide, polyacrylonitrile, polyphenylene ether, polyphenylene sulfide, polyetherketone, and polyaryletherketone.

[0014] An application of a high-efficiency reverse osmosis membrane is disclosed. The reverse osmosis membrane is used in the field of water treatment. The reverse osmosis membrane is used in conjunction with a turbulence device to induce continuous or periodic turbulence on the membrane surface, thereby reducing the membrane fouling rate and extending the chemical cleaning cycle.

[0015] Graphitic carbon nitride and sodium tripolyphosphate were mixed and dispersed in deionized water. Phosphorus-doped modified carbon nitride quantum dots were generated by utilizing the cavitation effect of ultrasound and high-temperature, high-pressure treatment in a reactor. The introduction of phosphorus atoms in the preparation of modified carbon nitride quantum dots effectively modulated the electronic structure of graphitic carbon nitride, narrowing its band gap and resulting in a wider absorption range and higher utilization efficiency for visible light. Under visible light irradiation, the modified carbon nitride quantum dots can more efficiently generate highly oxidizing reactive oxygen species such as hydroxyl radicals and superoxide radicals. These reactive oxygen species can oxidize and decompose complex organic pollutants attached to the membrane surface. This strongly complements the antifouling effect of cocamidopropyl hydroxysulfonate in the formulation, effectively solving the problem of stubborn organic fouling that is difficult to treat with traditional membranes, achieving deep cleaning and regeneration of the membrane surface.

[0016] The reactive oxygen species generated by photocatalysis can effectively destroy the cell membranes and nucleic acids of bacteria and viruses, thereby killing microorganisms or inhibiting their proliferation, and fundamentally inhibiting the formation of biofilms. Biofilms are one of the most intractable and difficult-to-remove forms of fouling in reverse osmosis membranes. The introduction of modified carbon nitride quantum dots makes the modified membrane surface unsuitable for microbial growth, greatly extending the chemical cleaning cycle caused by biofouling.

[0017] Phosphorus doping introduces PN and PO groups into the graphitic carbon nitride structure, which themselves possess good hydrophilicity. Simultaneously, the abundant functional groups on the surface of the modified carbon nitride quantum dots can form stronger hydrogen or covalent bonds with the crosslinked networks of polyvinyl alcohol and polyacrylic acid, further reducing the water contact angle on the membrane surface and enhancing the penetration and spreading of water molecules. This not only increases the water flux but also further blocks the adhesion of contaminants by forming a dense hydration layer. Stronger interfacial forces firmly lock the modified carbon nitride quantum dots within the polymer coating, preventing dissolution and loss during long-term operation or cleaning, thus ensuring the durability of the self-cleaning effect.

[0018] Due to the visible light response of modified carbon nitride quantum dots, they can be activated without expensive ultraviolet light sources, making it possible to integrate low-power LED visible light sources inside reverse osmosis membrane modules. The system can turn on the light source at night or periodically for online self-cleaning without stopping the system to add chemicals, achieving low-energy, online, non-chemical membrane cleaning and maintenance.

[0019] Modified carbon nitride quantum dots are mainly composed of three elements: carbon, nitrogen, and phosphorus, all of which are abundant in nature and do not contain any toxic metals. This avoids the risk of metal ion leaching that may exist in traditional metal-based photocatalysts such as titanium dioxide, and will not cause secondary pollution to the produced water quality, which meets the requirements of green chemistry development.

[0020] Introducing a turbulence-inducing device into reverse osmosis membrane applications, used in conjunction with the high-efficiency self-cleaning reverse osmosis membrane described in this invention, produces a synergistic effect. The turbulence-inducing device disrupts the stable flow pattern on the membrane surface, forcibly generating turbulence, thus optimizing the hydrodynamic environment at the membrane-liquid interface and enhancing the mass transfer process on the membrane surface. This effectively removes concentrated salt ions, colloids, and organic matter from the membrane surface rapidly, significantly reducing concentration polarization. This not only increases permeate flux and reduces operating energy consumption under the same operating pressure but also prevents solute supersaturation precipitation, fundamentally reducing the risk of inorganic salt scaling. Simultaneously, the continuous fluid shear force generated by the device creates a highly efficient physical scouring effect on the membrane surface. This effect synergizes deeply with the membrane's own photocatalytic function: the scouring action can partially peel off contaminants before they firmly adhere, reducing the burden on the self-cleaning coating; it can also more thoroughly remove fouling layers that have been chemically degraded or loosened. Furthermore, this unstable flow pattern greatly increases the difficulty of microbial attachment, forming a dual defense against biofilm formation together with the modified layer on the membrane surface.

[0021] The beneficial effects of this invention are: This invention constructs a multi-layered, synergistic self-cleaning system by introducing phosphorus-doped modified carbon nitride quantum dots, in conjunction with zwitterionic components and a turbulence-inducing device in the formulation. Phosphorus doping effectively modulates the electronic structure of graphitic carbon nitride, narrowing its band gap and significantly improving visible light absorption and utilization efficiency. This enables it to efficiently generate highly oxidizing reactive oxygen species under visible light irradiation, achieving deep degradation of organic pollutants on the membrane surface and strongly complementing the antifouling effect of zwitterions. Simultaneously, photocatalysis effectively disrupts microbial structures and inhibits biofilm formation. The hydrophilic groups introduced by phosphorus doping, combined with the abundant functional groups on the quantum dot surface, not only enhance the interfacial bonding with the polymer network, ensuring functional durability, but also improve membrane hydrophilicity, promoting the formation of a dense hydration layer and further blocking pollutants. When used in conjunction with a turbulence device, the generated turbulence not only enhances membrane mass transfer and significantly reduces concentration polarization, thus lowering the risk of fouling and operating energy consumption, but its fluid shear force also works in deep synergy with the photocatalytic function. Physical flushing can prevent pollutants from adhering firmly and efficiently remove the fouling layer that has been chemically degraded. Ultimately, through the synergistic effect of chemical self-cleaning and physical turbulence, the comprehensive benefits of increased membrane flux, significantly extended cleaning cycle, improved system recovery rate, and reduced operating energy consumption are achieved. Detailed Implementation

[0022] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with embodiments, is provided below.

[0023] It should be noted that, unless otherwise specified, the present invention does not specifically limit the source of the raw materials used in the following embodiments. Commercially available products or products prepared by conventional preparation methods that are well known to those skilled in the art can be used. Experimental methods that do not specify specific conditions are all conventional methods and conventional conditions well known in the art.

[0024] Example 1 Preparation of aqueous solution: m-phenylenediamine, sodium dodecyl sulfate, dimethyl sulfoxide and deionized water are mixed to obtain an aqueous solution; the aqueous solution is formulated as follows, by mass percentage: m-phenylenediamine 3%, sodium dodecyl sulfate 1%, dimethyl sulfoxide 6%, and the balance is water.

[0025] Preparation of the oil phase solution: Tristyroyl chloride and Isopar G were mixed to obtain an oil phase solution; the oil phase solution was formulated as follows, with 0.2% tristyroyl chloride and the balance Isopar G by mass percentage.

[0026] The modified liquid has the following formula by weight: 4 parts polyvinyl alcohol, 2 parts polyacrylic acid, 0.4 parts citric acid, 0.2 parts cocamidopropyl hydroxysulfonyl betaine, 0.08 parts modified carbon nitride quantum dot dispersion, and 70 parts deionized water.

[0027] The preparation method of the modified carbon nitride quantum dot dispersion is as follows. Graphitic carbon nitride and sodium tripolyphosphate were mixed at a mass ratio of 1:4 and dispersed in deionized water. The mixture was ultrasonically mixed for 1.5 h, then transferred to a reaction vessel and reacted at 190 °C for 7 h. After naturally cooling to room temperature, the mixture was centrifuged at 9000 rpm for 18 min. The supernatant was dialyzed through a dialysis bag with a molecular weight of 1000 Da for 36 h to obtain the modified carbon nitride quantum dot dispersion.

[0028] The modified liquid is prepared as follows: S4-1: Heat half the mass of deionized water to 85 °C, add polyvinyl alcohol under stirring, and continue stirring for 45 min to obtain solution A; S4-2: Cool the solution A to 55 °C, add polyacrylic acid and cocamidopropyl hydroxysulfonate betaine in sequence under stirring, stir for 45 min to obtain solution B; S4-3: Cool the solution B to below 35 °C, add the remaining deionized water, and add the modified carbon nitride quantum dot dispersion. Stir for 45 min, and finally add citric acid and continue stirring for 8 min to obtain the modified solution.

[0029] A method for preparing a high-efficiency reverse osmosis membrane, the specific steps of which are as follows: S1-1: Immerse the polysulfone-based membrane in an aqueous solution for 20 seconds, remove and allow it to dry slightly. Then, coat the membrane with an oil-phase solution for interfacial polymerization for 30 seconds. The coating amount is 100 mg / m². 2 The reverse osmosis membrane was obtained by drying at 70 °C for 5 min. S1-2: Apply the modified solution to the surface of the reverse osmosis membrane at a coating amount of 110 mg / m³. 2 After drying at 75°C for 3 minutes, the high-efficiency reverse osmosis membrane is obtained.

[0030] Example 2 Preparation of aqueous solution: m-phenylenediamine, sodium dodecyl sulfate, dimethyl sulfoxide and deionized water are mixed to obtain an aqueous solution; the aqueous solution is formulated as follows, by mass percentage: m-phenylenediamine 0.5%, sodium dodecyl sulfate 0.1%, dimethyl sulfoxide 3%, and the balance is water.

[0031] Preparation of the oil phase solution: Tristyroyl chloride and Isopar G were mixed to obtain an oil phase solution; the oil phase solution was formulated as follows, with 0.1% tristyroyl chloride and the balance Isopar G by mass percentage.

[0032] The modified liquid has the following formula by weight: 3 parts polyvinyl alcohol, 1 part polyacrylic acid, 0.3 parts citric acid, 0.1 parts cocamidopropyl hydroxysulfonyl betaine, 0.05 parts modified carbon nitride quantum dot dispersion, and 60 parts deionized water.

[0033] The preparation method of the modified carbon nitride quantum dot dispersion is as follows. Graphite-phase carbon nitride and sodium tripolyphosphate were mixed at a mass ratio of 1:3 and dispersed in deionized water. The mixture was ultrasonically mixed for 1 h, then transferred to a reaction vessel and reacted at 180 °C for 6 h. After naturally cooling to room temperature, the mixture was centrifuged at 8000 rpm for 15 min. The supernatant was dialyzed through a dialysis bag with a molecular weight of 1000 Da for 24 h to obtain the modified carbon nitride quantum dot dispersion.

[0034] The modified liquid is prepared as follows: S4-1: Heat half the mass of deionized water to 8 ℃, add polyvinyl alcohol under stirring, and continue stirring for 30 min to obtain solution A; S4-2: Cool the solution A to 50 °C, add polyacrylic acid and cocamidopropyl hydroxysulfonate betaine in sequence under stirring, stir for 30 min to obtain solution B; S4-3: Cool the solution B to below 35 °C, add the remaining deionized water, and add the modified carbon nitride quantum dot dispersion. Stir for 30 min, and finally add citric acid and continue stirring for 5 min to obtain the modified solution.

[0035] A method for preparing a high-efficiency reverse osmosis membrane, the specific steps of which are as follows: S1-1: Immerse the polysulfone-based membrane in an aqueous solution for 10 seconds, remove and allow it to dry slightly. Then, coat the membrane with an oil-phase solution for 10 seconds to perform interfacial polymerization. The coating amount is 100 mg / m². 2 The reverse osmosis membrane was obtained by drying at 70 °C for 5 min. S1-2: Apply the modified solution to the surface of the reverse osmosis membrane at a coating amount of 110 mg / m³. 2 After drying at 75°C for 3 minutes, the high-efficiency reverse osmosis membrane is obtained.

[0036] Example 3 Preparation of aqueous solution: m-phenylenediamine, sodium dodecyl sulfate, dimethyl sulfoxide and deionized water are mixed to obtain an aqueous solution; the aqueous solution is formulated as follows, by mass percentage: m-phenylenediamine 5%, sodium dodecyl sulfate 2%, dimethyl sulfoxide 10%, and the balance is water.

[0037] Preparation of the oil phase solution: Tristyroyl chloride and Isopar G were mixed to obtain an oil phase solution; the oil phase solution was formulated as follows, with 0.3% tristyroyl chloride and the balance Isopar G by mass percentage.

[0038] The modified liquid has the following formula by weight: 5 parts polyvinyl alcohol, 3 parts polyacrylic acid, 0.5 parts citric acid, 0.3 parts cocamidopropyl hydroxysulfonyl betaine, 0.1 parts modified carbon nitride quantum dot dispersion, and 80 parts deionized water.

[0039] The preparation method of the modified carbon nitride quantum dot dispersion is as follows. Graphite-phase carbon nitride and sodium tripolyphosphate were mixed at a mass ratio of 1:5 and dispersed in deionized water. The mixture was ultrasonically mixed for 2 h, then transferred to a reaction vessel and reacted at 200 °C for 8 h. After naturally cooling to room temperature, the mixture was centrifuged at 10,000 rpm for 20 min. The supernatant was dialyzed through a dialysis bag with a molecular weight of 1000 Da for 48 h to obtain the modified carbon nitride quantum dot dispersion.

[0040] The modified liquid is prepared as follows: S4-1: Heat half the mass of deionized water to 90 °C, add polyvinyl alcohol under stirring, and continue stirring for 60 min to obtain solution A; S4-2: Cool the solution A to 60 °C, and add polyacrylic acid and cocamidopropyl hydroxysulfonate betaine in sequence under stirring. Stir for 60 min to obtain solution B. S4-3: Cool the solution B to below 35 °C, add the remaining deionized water, and add the modified carbon nitride quantum dot dispersion. Stir for 60 min, and finally add citric acid and continue stirring for 10 min to obtain the modified solution.

[0041] A method for preparing a high-efficiency reverse osmosis membrane, the specific steps of which are as follows: S1-1: Immerse the polysulfone-based membrane in an aqueous solution for 30 seconds, remove and allow it to dry slightly. Then, coat the membrane with an oil-phase solution and perform an interfacial polymerization reaction for 60 seconds. The coating amount is 100 mg / m². 2 The reverse osmosis membrane was obtained by drying at 70 °C for 5 min. S1-2: Apply the modified solution to the surface of the reverse osmosis membrane at a coating amount of 110 mg / m³. 2 After drying at 75°C for 3 minutes, the high-efficiency reverse osmosis membrane is obtained.

[0042] Example 4 The difference between Example 4 and Example 1 is that the reverse osmosis membrane in this example is used in conjunction with a flow-turbulence device. The flow-turbulence device can be a mesh spacer disposed between the membrane sheets, an array of protrusions etched on the surface of the membrane bag, or a spiral guide groove disposed on the inner wall of the membrane tube. Specifically, the flow-turbulence device in this example is a mesh spacer disposed between the membrane sheets; all other aspects are consistent with Example 1.

[0043] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that sodium tripolyphosphate was not added in the preparation of the modified carbon nitride quantum dot dispersion, while all other aspects remained the same as in Example 1.

[0044] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that commercially available graphitic carbon nitride is used instead of modified carbon nitride quantum dots, while all other aspects remain the same as in Example 1.

[0045] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that modified carbon nitride quantum dots are not added to the modified liquid, while all other aspects are the same as in Example 1.

[0046] Performance testing The performance of the reverse osmosis membranes obtained in the examples and comparative examples was tested. A sodium chloride solution with a mass concentration of 3000 mg / L was used as the feed liquid, the feed liquid temperature was controlled at 25.0 ± 0.2℃, and the operating pressure was 5 MPa. The initial water flux of the reverse osmosis membrane was calculated as J = Q / (A·t), where J is the initial water flux (gfd); Q is the water permeation rate (L); and A is the effective membrane area of ​​the composite reverse osmosis membrane (m²). 2 t represents time, in hours. Desalination rate (%) = (feed liquid conductivity - filtrate conductivity) / feed liquid conductivity × 100%. The experimental results are shown in Table 1.

[0047] Table 1 Group Initial water flux (gfd) Desalination rate (%) Example 1 41.4 99.76 Example 2 41.0 99.71 Example 3 40.9 99.69 Comparative Example 1 39.8 99.54 Comparative Example 2 38.4 99.38 Comparative Example 3 38.7 99.60 Antifouling performance test The membrane fouling process was simulated by running a solution of 3000 mg / L NaCl and 400 mg / L bovine serum albumin at 5 MPa pressure and 25.0 ± 0.2℃ for 4 h. After the fouling operation, the system was drained, the membrane surface was rinsed with deionized water, and then the system was run under visible light irradiation for 1 h. The water flux of the membrane was then tested again under standard conditions. The flux recovery rate after fouling was calculated as: FRR (%) = (J2 / J0) × 100%, where J0 is the initial water flux and J2 is the stable water flux after self-cleaning. The experimental results are shown in Table 2.

[0048] Table 2 Group Post-contamination flux recovery rate (%) Example 1 96.7 Example 2 95.4 Example 3 95.0 Example 4 97.3 Comparative Example 1 88.4 Comparative Example 2 78.2 Comparative Example 3 69.1 As can be seen from the examples and comparative data, the reverse osmosis membrane prepared by the present invention has excellent water flux, desalination rate and fouling resistance and self-cleaning function.

[0049] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention are still within the scope of the present invention.

Claims

1. A method for preparing a high-efficiency reverse osmosis membrane, characterized in that, The specific steps of the preparation method are as follows: S1-1: Immerse the polysulfone-based membrane in an aqueous solution, remove it and allow it to dry slightly. Then coat the membrane with an oil solution to carry out an interfacial polymerization reaction. After curing, a reverse osmosis membrane is obtained. S1-2: The modified liquid is applied to the surface of the reverse osmosis membrane and dried to obtain the high-efficiency reverse osmosis membrane; The modified liquid has the following formula by weight: 3-5 parts polyvinyl alcohol, 1-3 parts polyacrylic acid, 0.3-0.5 parts citric acid, 0.1-0.3 parts cocamidopropyl hydroxysulfonyl betaine, 0.05-0.1 parts modified carbon nitride quantum dot dispersion, and 60-80 parts deionized water. The preparation method of the modified carbon nitride quantum dot dispersion is as follows. Graphite-phase carbon nitride and sodium tripolyphosphate were mixed and dispersed in deionized water and ultrasonically mixed for 1-2 h. Then, the mixture was transferred to a reaction vessel and reacted at 180-200 °C for 6-8 h. After naturally cooling to room temperature, the mixture was centrifuged at 8000-10000 rpm for 15-20 min. The supernatant was dialyzed through a dialysis bag with a molecular weight of 1000 Da for 24-48 h to obtain the modified carbon nitride quantum dot dispersion.

2. The method for preparing a high-efficiency reverse osmosis membrane according to claim 1, characterized in that, The graphitic carbon nitride and sodium tripolyphosphate are mixed at a mass ratio of 1:(3~5).

3. The method for preparing a high-efficiency reverse osmosis membrane according to claim 1, characterized in that, The modified liquid is prepared as follows: S4-1: Heat half the mass of deionized water to 80~90 ℃, add polyvinyl alcohol under stirring, and continue stirring for 30~60 min to obtain solution A; S4-2: Cool the solution A to 50~60 ℃, add polyacrylic acid and cocamidopropyl hydroxysulfonate betaine in sequence under stirring, stir for 30~60 min to obtain solution B; S4-3: Cool the solution B to below 35 °C, add the remaining deionized water, and add the modified carbon nitride quantum dot dispersion. Stir for 30-60 min, and finally add citric acid. Continue stirring for 5-10 min to obtain the modified solution.

4. The method for preparing a high-efficiency reverse osmosis membrane according to claim 1, characterized in that, The aqueous solution is formulated as follows (by mass percentage): 0.5-5% polyfunctional amine, 0.1-2% surfactant, 3-10% polar solvent, and the balance being water. Wherein, the polyfunctional amine is one or more of m-phenylenediamine, p-phenylenediamine, ethylenediamine, propylenediamine, and butanediamine; the surfactant is one or more of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, and sodium dodecyl sulfonate; and the polar solvent is one or two of dimethyl sulfoxide and N-methylpyrrolidone.

5. The method for preparing a high-efficiency reverse osmosis membrane according to claim 1, characterized in that, The oil phase solution is formulated as follows: by mass percentage, acyl halide 0.1-0.3% and oil phase solvent balance. The acyl halide includes one or more of pyromellitic chlorobenzene chloride, phthaloyl chloride, orthophthaloyl chloride, isophthaloyl chloride, biphenyl dimethyl chloride, and benzene disulfonyl chloride; the oil phase solvent includes one or more of n-hexane, Isopar G, and Isopar L.

6. The method for preparing a high-efficiency reverse osmosis membrane according to claim 1, characterized in that, The contact time between the base film surface and the aqueous solution is 10-30 s; the contact time between the base film surface and the oil solution is 10-60 s.

7. A high-efficiency reverse osmosis membrane, prepared by the preparation method according to any one of claims 1 to 6.

8. An application of the high-efficiency reverse osmosis membrane as described in claim 7, characterized in that, The reverse osmosis membrane is used in the field of water treatment. The reverse osmosis membrane is used in conjunction with a turbulence device to induce continuous or periodic turbulence on the membrane surface, thereby reducing the membrane fouling rate and extending the chemical cleaning cycle.