A high-performance reverse osmosis membrane and a preparation method thereof

Abstract

The application relates to the technical field of reverse osmosis membranes, in particular to a high-performance reverse osmosis membrane and a preparation method thereof. The reverse osmosis membrane is prepared by the method. The method comprises the following steps: growing a cuprous oxide nanoparticle layer on a polysulfone porous membrane layer in situ, so as to obtain a first combined membrane piece; growing a polyacrylamide layer on the cuprous oxide nanoparticle layer in the first combined membrane piece, so as to obtain a second combined membrane piece; and growing a polyamide layer on the polyacrylamide layer in the second combined membrane piece, so as to obtain a high-performance reverse osmosis membrane. The high-performance reverse osmosis membrane prepared by the application has high water flux and high desalination rate, and the high water flux and the high desalination rate are stable.

Description

Technical Field

[0001] This invention relates to the field of reverse osmosis membrane technology, and specifically to a high-performance reverse osmosis membrane and its preparation method. Background Technology

[0002] The trade-off between permeability and selectivity in reverse osmosis membrane performance has always been one of the most critical scientific challenges and technological bottlenecks in the field of membrane separation, and a key issue that researchers in academia and R&D engineers in industry have been continuously working to overcome. How to increase water flux while maintaining or even significantly improving desalination rates is crucial for substantially reducing system operating pressure, energy consumption and carbon emissions, and improving water production efficiency.

[0003] At the forefront of academia, researchers are dedicated to breaking through this inherent equilibrium at the level of mass transfer mechanisms. This is achieved by developing novel monomers to improve performance. For example, existing literature (Li L, Zhang S, Zhang X, et al. Polyamide thin film composite membranes prepared from 3,4′, 5-biphenyl triacyl chloride, 3,3′,5,5′-biphenyl tetraacyl chloride and m-phenylenediamine[J]. Journal of Membrane Science.) uses synthesized 3,4′,5-biphenyltriacyl chloride (BTRC) and 3,3′,5,5′-biphenyltetraacyl chloride (BTEC) as oil-phase monomers for interfacial polymerization with m-phenylenediamine. Compared to traditional pyromellitic triacyl chloride, this method does indeed significantly improve desalination efficiency, but the water flux decreases.

[0004] Chinese invention patent application No. 202211533186.8 discloses a high-performance reverse osmosis membrane and its preparation method. This method involves forming a micron-scale prism structure on the surface of a polysulfone-based membrane using a roller mold through cold pressing, thereby increasing the specific surface area of ​​the functional layer of the reverse osmosis membrane and thus improving water flux without sacrificing desalination rate. However, this method, through physical cold pressing, may affect the surface pore size and porosity of the polysulfone-based membrane, thus affecting the subsequent interfacial polymerization process and leading to fluctuations in water flux and desalination rate performance.

[0005] Therefore, it is necessary to provide a high-performance reverse osmosis membrane and its preparation method to solve the problem that it is difficult to simultaneously improve water flux and desalination rate performance in the existing technology, as well as to solve the problem of fluctuation in water flux and desalination rate performance in the existing technology. Summary of the Invention

[0006] The purpose of this invention is to provide a high-performance reverse osmosis membrane and its preparation method, the specific technical solution of which is as follows:

[0007] In a first aspect, the present invention provides a method for preparing a high-performance reverse osmosis membrane, comprising:

[0008] Step S1: The polysulfone porous membrane layer is subjected to a first immersion treatment in a copper salt aqueous solution with a mass percentage of 0.1%~0.5%, a second immersion treatment in a sodium hydroxide aqueous solution with a pH of 11~12, and a third immersion treatment in an ascorbic acid aqueous solution with a mass percentage of 0.4%~0.6%, to obtain a cuprous oxide nanoparticle layer grown in situ on the polysulfone porous membrane layer, which is the first combined membrane.

[0009] Step S2: After the first combined membrane is immersed in the reaction solution for the fourth time, the first combined membrane is taken out and then subjected to visible light irradiation to obtain a polyacrylamide layer grown on the cuprous oxide nanoparticle layer in the first combined membrane, thus obtaining the second combined membrane.

[0010] The reaction solution comprises the following components by mass percentage: 3%–6% acrylamide aqueous solution, 0.1%–0.5% ethylene glycol dimethacrylate, and 1% ascorbic acid;

[0011] Step S3: The second combined membrane is sequentially immersed in an aqueous solution for a fifth immersion treatment and in an oil phase solution for a sixth immersion treatment. Then, it is dried to obtain a polyamide layer grown on the polyacrylamide layer in the second combined membrane, thus obtaining a high-performance reverse osmosis membrane.

[0012] The aqueous phase solution comprises a polyamine aqueous solution with a mass percentage of 2% to 5%; the oil phase solution comprises an acyl chloride solution with a mass percentage of 0.08% to 0.15%.

[0013] Optionally, the copper salt aqueous solution includes an aqueous solution of copper sulfate.

[0014] Optionally, the copper salt aqueous solution includes an aqueous solution of copper sulfate pentahydrate.

[0015] Optionally, the first soaking treatment uses a soaking time of 3 to 5 minutes and a soaking temperature of 25 to 30°C;

[0016] The second soaking treatment uses a soaking time of 5-10 minutes and a soaking temperature of 10-15℃;

[0017] The third soaking treatment uses a soaking time of 60-90 minutes and a soaking temperature of 65-75℃.

[0018] The process includes removing excess copper salt aqueous solution from the surface of the polysulfone porous membrane layer using a rubber roller after the first immersion treatment and before the second immersion treatment.

[0019] The process includes removing excess sodium hydroxide aqueous solution from the surface of the polysulfone porous membrane layer using a rubber roller after the second immersion treatment and before the third immersion treatment.

[0020] The third soaking treatment also includes washing away excess ascorbic acid aqueous solution from the surface of the polysulfone porous membrane with pure water.

[0021] Optionally, the fourth soaking treatment uses a soaking time of 3-5 minutes and a soaking temperature of 25-30°C;

[0022] The visible light irradiation treatment uses an irradiation intensity of 50 mW / cm² and an irradiation time of 5 min;

[0023] The process includes removing excess reaction solution from the surface of the first composite membrane using a rubber roller after the fourth immersion treatment and before the visible light irradiation treatment.

[0024] Optionally, the fifth soaking treatment uses a soaking time of 30 seconds and a soaking temperature of 25°C.

[0025] The sixth soaking treatment uses a soaking time of 10 seconds and a soaking temperature of 25°C.

[0026] The process includes removing excess polyamine aqueous solution from the surface of the second combined membrane using a rubber roller after the fifth immersion treatment and before the sixth immersion treatment.

[0027] The polyamine aqueous solution includes an aqueous solution of m-phenylenediamine; the solute used in the oil phase acyl chloride solution includes trimesoyl chloride, and the solvent used includes n-hexane;

[0028] The drying process uses a drying temperature of 60°C and a drying time of 1 minute.

[0029] Optionally, the preparation method of the high-performance reverse osmosis membrane further includes the preparation of the polysulfone porous membrane layer; specifically, the impurity-removed polysulfone solution is first degassed under vacuum, and then extruded through a slit and uniformly coated onto a substrate; wherein the substrate is pre-fixed on a carrier; then, a porous polysulfone membrane is formed on the substrate through phase inversion, thus obtaining the polysulfone porous membrane layer;

[0030] The polysulfone solution has a mass percentage of 15% to 18%;

[0031] The slit width is 100~300μm;

[0032] The coating amount of the polysulfone solution on the substrate is 0.03~0.06 g / cm³. 2 ;

[0033] The base layer includes non-woven fabric.

[0034] Optionally, the parameters used in the vacuum degassing include a vacuum degree of -0.095MPa to -0.098MPa, a degassing time of 5 to 6 hours, and a degassing temperature of 25 to 30°C.

[0035] The phase transformation is carried out by a solidification bath at a temperature of 15°C.

[0036] In a second aspect, the present invention provides a high-performance reverse osmosis membrane, which is prepared by the aforementioned method for preparing a high-performance reverse osmosis membrane.

[0037] Optionally, the high-performance reverse osmosis membrane has a desalination rate of over 99.40% and a water flux of over 110 LMH.

[0038] The application of the technical solution of the present invention has at least the following beneficial effects:

[0039] This invention provides a method for preparing a high-performance reverse osmosis membrane, capable of producing a membrane with both high water flux and high desalination rate, and with stable performance in both aspects. Specifically, in step S1, a cuprous oxide nanoparticle layer is obtained by in-situ growth on a polysulfone porous membrane layer. This cuprous oxide nanoparticle layer serves as an intermediate layer, providing support and also exhibiting a "groove effect." When water reaches the cuprous oxide nanoparticle layer, it can rapidly diffuse to the polysulfone porous membrane layer through the high permeability of its grooves. This effectively provides a "shortcut" for water transport, significantly reducing the total mass transfer resistance and increasing water flux without altering the high-performance reverse osmosis membrane's retention performance. Furthermore, in step S2, after visible light irradiation, the cuprous oxide nanoparticles are excited by absorbing visible light, causing their valence band electrons to transition to the conduction band, leaving positively charged holes in the valence band. These holes and the transitioned electrons form highly active electron-hole pairs. Simultaneously… To effectively block the electron-hole recombination pathway, ascorbic acid, acting as a hole sacrificial agent, is introduced into the reaction solution and preferentially and rapidly oxidizes valence band holes. This significantly increases the lifetime and concentration of transition electrons, maximizing the efficiency of converting light energy into chemical energy. Consequently, transition electrons are enriched and subsequently captured by dissolved oxygen in the reaction solution. Through a single-electron reduction process, hydroxyl radicals are generated. These hydroxyl radicals attack the double bonds of the acrylamide monomer, making them active primary radicals and initiating chain polymerization. Simultaneously, the bifunctional crosslinking agent ethylene glycol dimethacrylate is introduced into the polymer chain during chain polymerization. This crosslinking agent bridges multiple molecular chains through its methacrylate groups at both ends, thereby directly constructing a stable three-dimensional crosslinked polyacrylamide layer during polymerization.

[0040] Furthermore, in order to improve both water flux and desalination rate, this invention combines steps S2 and S3 to form an ultrathin, dense, and defect-free polyamide layer. The specific principle is as follows:

[0041] On the one hand, the polyacrylamide layer formed in step S2 is rich in amide groups and has strong hydrophilicity. It effectively adsorbs and locks a large amount of polyamine aqueous solution through hydrogen bonding, creating a local high-concentration polyamine monomer reaction pool, providing an abundant supply of polyamine monomers for interfacial polymerization. From a thermodynamic point of view, the higher concentration of polyamine monomers directly increases their effective concentration at the oil-water interface, significantly increasing the probability of reaction with acyl chloride monomers, thereby greatly promoting the improvement of the crosslinking degree of the polyamide network. A higher degree of crosslinking means that the pore size of the network structure in the polymer network is smaller and the distribution is more uniform, which is the structural basis for achieving a high desalination rate.

[0042] On the other hand, in conventional interfacial polymerization, if a high concentration of polyamine monomers is used alone, the diffusion rate into the acyl chloride solution is too fast and difficult to control, resulting in the formation of a loose and unevenly thick polyamide layer. However, the polyacrylamide layer formed in step S2 of this invention, as a three-dimensional gel layer, achieves slow-release regulation of the diffusion rate of polyamine monomers through the synergistic effect of physical steric hindrance and chemical hydrogen bond anchoring. This transforms interfacial polymerization from an "explosive" reaction to a "controllable" reaction, providing key kinetic assurance for the formation of an ultrathin, dense, and defect-free polyamide layer. Ultimately, this synergistically produces a high-performance reverse osmosis membrane with both high water flux and high desalination rate, and stable performance in both areas. This is of great significance for promoting the development of membrane-based water treatment and energy conservation and emission reduction.

[0043] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the figures. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0045] Figure 1 This is a schematic diagram of the structure of a high-performance reverse osmosis membrane in an embodiment of the present invention.

[0046] Explanation of reference numerals in the attached figures: 1. Polysulfone porous membrane layer; 1.1. Base layer; 1.2. Porous polysulfone membrane; 2. Cuprous oxide nanoparticle layer; 3. Polyacrylamide layer; 4. Polyamide layer. Detailed Implementation

[0047] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0048] Example:

[0049] See Figure 1 A method for preparing a high-performance reverse osmosis membrane, comprising:

[0050] Step S1: The polysulfone porous membrane layer 1 is subjected to a first immersion treatment in a copper salt aqueous solution (specifically, copper sulfate pentahydrate aqueous solution) with a mass percentage of 0.1%~0.5% (specifically 0.3%), a second immersion treatment in a sodium hydroxide aqueous solution with a pH of 11~12 (specifically 12), and a third immersion treatment in an ascorbic acid aqueous solution with a mass percentage of 0.4%~0.6% (specifically 0.4%), to obtain a cuprous oxide nanoparticle layer 2 grown in situ on the polysulfone porous membrane layer 1, which is the first combined membrane.

[0051] Step S2: After the first combined membrane is immersed in the reaction solution for the fourth time, the first combined membrane is taken out and then subjected to visible light irradiation to obtain a polyacrylamide layer 3 grown on the cuprous oxide nanoparticle layer 2 in the first combined membrane, thus obtaining the second combined membrane.

[0052] The reaction solution comprises the following components by mass percentage: 3%~6% (specifically 5%) acrylamide aqueous solution, 0.1%~0.5% (specifically 0.2%) ethylene glycol dimethacrylate, and 1% ascorbic acid;

[0053] Step S3: The second combined membrane is sequentially immersed in an aqueous solution for a fifth immersion treatment and in an oil phase solution for a sixth immersion treatment. Then, it is dried to obtain a polyamide layer 4 grown on the polyacrylamide layer 3 in the second combined membrane, thus obtaining a high-performance reverse osmosis membrane.

[0054] The aqueous phase solution is a polyamine aqueous solution with a mass percentage of 2% to 5% (specifically 3%); the oil phase solution is an acyl chloride solution with a mass percentage of 0.08% to 0.15% (specifically 0.12%).

[0055] The first soaking treatment uses a soaking time of 3-5 minutes (specifically 3 minutes) and a soaking temperature of 25-30℃ (specifically 25℃).

[0056] The second soaking treatment uses a soaking time of 5-10 minutes (specifically 5 minutes) and a soaking temperature of 10-15℃ (specifically 15℃).

[0057] The third soaking treatment uses a soaking time of 60-90 minutes (specifically 70 minutes) and a soaking temperature of 65-75°C (specifically 70°C).

[0058] The process includes removing excess copper salt aqueous solution from the surface of the polysulfone porous membrane 1 using a rubber roller after the first immersion treatment and before the second immersion treatment.

[0059] The process includes removing excess sodium hydroxide aqueous solution from the surface of the polysulfone porous membrane 1 using a rubber roller after the second immersion treatment and before the third immersion treatment.

[0060] The third soaking treatment also includes washing away excess ascorbic acid aqueous solution from the surface of the polysulfone porous membrane 1 with pure water.

[0061] The fourth soaking treatment uses a soaking time of 3-5 minutes (specifically 3 minutes) and a soaking temperature of 25-30℃ (specifically 25℃).

[0062] The visible light irradiation treatment uses an irradiation intensity of 50 mW / cm² and an irradiation time of 5 min;

[0063] The process includes removing excess reaction solution from the surface of the first composite membrane using a rubber roller after the fourth immersion treatment and before the visible light irradiation treatment.

[0064] The fifth soaking treatment uses a soaking time of 30 seconds and a soaking temperature of 25°C.

[0065] The sixth soaking treatment uses a soaking time of 10 seconds and a soaking temperature of 25°C.

[0066] The process includes removing excess polyamine aqueous solution from the surface of the second combined membrane using a rubber roller after the fifth immersion treatment and before the sixth immersion treatment.

[0067] The polyamine aqueous solution is an aqueous solution of m-phenylenediamine; the solute used in the oil phase acyl chloride solution is trimesoyl chloride, and the solvent used is n-hexane;

[0068] The drying process uses a drying temperature of 60°C and a drying time of 1 minute.

[0069] The method for preparing the high-performance reverse osmosis membrane further includes preparing the polysulfone porous membrane layer 1; specifically, the impurity-removed polysulfone solution is first degassed under vacuum, and then extruded through a slit and uniformly coated onto the substrate 1.1; wherein the substrate 1.1 is pre-fixed on a carrier (specifically a stainless steel plate); then, a porous polysulfone membrane 1.2 is formed on the substrate 1.1 through phase transformation, thus obtaining the polysulfone porous membrane layer 1;

[0070] The polysulfone solution has a mass percentage of 15% to 18% (specifically 15%).

[0071] The slit width is 100~300μm (specifically 200μm);

[0072] The coating amount of the polysulfone solution on the base layer 1.1 is 0.03~0.06 g / cm³.2 (Specifically 0.05g / cm) 2 );

[0073] The base layer 1.1 is non-woven fabric.

[0074] The parameters used for vacuum degassing include a vacuum degree of -0.095MPa to -0.098MPa (specifically -0.098MPa), a degassing time of 5 to 6 hours (specifically 6 hours), and a degassing temperature of 25 to 30°C (specifically 30°C).

[0075] The phase transformation is carried out by a coagulation bath (specifically a pure water coagulation bath) at a temperature of 15°C.

[0076] Example 2:

[0077] Unlike Example 1, the mass percentage of the copper sulfate pentahydrate aqueous solution in step S1 is 0.1%.

[0078] Example 3:

[0079] Unlike Example 1, the mass percentage of the copper sulfate pentahydrate aqueous solution in step S1 is 0.5%.

[0080] Example 4:

[0081] Unlike Example 1, the mass percentage of the acrylamide aqueous solution in step S2 is 3%.

[0082] Example 5:

[0083] Unlike Example 1, the mass percentage of the acrylamide aqueous solution in step S2 is 6%.

[0084] Example 6:

[0085] Unlike Example 1, the mass percentage of ethylene glycol dimethacrylate in the reaction solution in step S2 is 0.1%.

[0086] Example 7:

[0087] Unlike Example 1, the mass percentage of ethylene glycol dimethacrylate in the reaction solution in step S2 is 0.5%.

[0088] Comparative Example 1:

[0089] Unlike Example 1, the mass percentage of the copper sulfate pentahydrate aqueous solution in step S1 is 0.08%.

[0090] Comparative Example 2:

[0091] Unlike Example 1, the mass percentage of the copper sulfate pentahydrate aqueous solution in step S1 is 0.6%.

[0092] Comparative Example 3:

[0093] Unlike Example 1, the mass percentage of the acrylamide aqueous solution in step S2 is 2%.

[0094] Comparative Example 4:

[0095] Unlike Example 1, the acrylamide aqueous solution in step S2 has a mass percentage of 7%.

[0096] Comparative Example 5:

[0097] Unlike Example 1, the mass percentage of ethylene glycol dimethacrylate in the reaction solution in step S2 is 0.6%.

[0098] Comparative Example 6:

[0099] Unlike Example 1, step S1 and the visible light irradiation treatment in step S2 are omitted. After the polysulfone porous membrane 1 undergoes a fourth immersion treatment, it is placed in an oven and treated at 60°C for 5 minutes to obtain a polyacrylamide layer 3 grown on the polysulfone porous membrane 1.

[0100] Comparative Example 7:

[0101] Unlike Example 1, step S2 is omitted, and the first combined membrane obtained in step S1 is directly subjected to step S3.

[0102] Comparative Example 8:

[0103] Unlike Example 1, steps S1 and S2 are omitted, and the polysulfone porous membrane 1 is directly subjected to step S3.

[0104] Four membrane samples from each of the reverse osmosis membranes prepared in Examples 1-7 and Comparative Examples 1-8 were placed on a cross-flow membrane testing platform and tested under the following conditions: operating pressure of 150 psi, raw water of 1500 ppm NaCl aqueous solution, temperature of 25°C, and pH of 7-8. The water flux (J) and desalination rate (R) of the four reverse osmosis membrane samples were calculated according to formulas a and b, and the average water flux and average desalination rate of the four reverse osmosis membrane samples were also calculated.

[0105] Calculation formula a: .

[0106] Wherein, water flux (J) refers to the volume (V) of water passing through a unit membrane area (S) per unit time (t) under the above test conditions, and the unit of water flux (J) is L·m -2·h -1 V is the permeate volume (in L); S is the effective surface area of ​​the reverse osmosis membrane (in m²). 2 ); t is the permeation time (in hours).

[0107] Calculation formula b: .

[0108] Where R represents the solute removal rate of the polyamide reverse osmosis membrane, i.e., the desalination rate (%); C p This indicates the concentration of the permeate after the raw water passes through the reverse osmosis membrane; C f This indicates the concentration of the raw water.

[0109] The performance data of the reverse osmosis membrane after testing are shown in Table 1.

[0110] Table 1 Reverse osmosis membrane performance data

[0111]

[0112] See Table 1 for data:

[0113] Comparing Example 1 and Comparative Example 1, it can be seen that the water flux of Comparative Example 1 is reduced. This is because the use of a lower mass percentage of copper sulfate pentahydrate aqueous solution in Comparative Example 1 leads to a reduction in the number of grown cuprous oxide nanoparticles, thereby reducing the "groove effect" and resulting in a decrease in water flux.

[0114] Comparing Example 1 and Comparative Example 2, it can be seen that the desalination rate of Comparative Example 2 is lower. This is because the use of a higher mass percentage of copper sulfate pentahydrate aqueous solution in Comparative Example 2 leads to an excessive number of cuprous oxide nanoparticles that are prone to accumulation, thereby reducing the number of transition electrons generated by visible light excitation. This results in a decrease in hydroxyl radicals, making it difficult to form a stable three-dimensional cross-linked polyacrylamide layer 3 in step S2. This directly affects the compactness of the polyamide layer 4 formed in step S3 and easily leads to defects in the polyamide layer 4 (such as defects with excessively large pore sizes), ultimately resulting in a decrease in the desalination rate.

[0115] Comparing Example 1 and Comparative Example 3, it can be seen that the desalination rate of Comparative Example 3 is lower. This is because the use of a lower mass percentage of acrylamide aqueous solution in Comparative Example 3 results in a thinner polyacrylamide layer 3. On the one hand, this leads to insufficient adsorption of diamine monomers, directly reducing the degree of crosslinking in interfacial polymerization, resulting in a larger pore size in the polyamide layer 4 and a lower desalination rate. On the other hand, the larger pore size of the polyamide layer 4 and the thinness of the polyacrylamide layer 3 make it easy for defects to form in the polyamide layer 4 and polyacrylamide layer 3 under test pressure, thus leading to a decrease in the desalination rate.

[0116] Comparing Example 1 and Comparative Example 4, it can be seen that the water flux of Comparative Example 4 decreased. This is because the use of a higher mass percentage of acrylamide aqueous solution in Comparative Example 4 resulted in a thicker polyacrylamide layer 3, which increased the water mass transfer resistance and thus reduced the water flux.

[0117] Comparing Example 1 and Comparative Example 5, it can be seen that the water flux of Comparative Example 5 decreased. This is because the use of a higher mass percentage of ethylene glycol dimethacrylate in Comparative Example 5 resulted in excessive cross-linking of the formed polyacrylamide layer 3, leading to increased water mass transfer resistance and thus a decrease in water flux.

[0118] Comparing Example 1 and Comparative Example 6, it can be seen that the water flux of Comparative Example 6 is significantly reduced. This is because in Comparative Example 6, step S1 and the visible light irradiation treatment in step S2 are omitted. The polysulfone porous membrane layer 1 is directly subjected to the fourth immersion treatment and then placed in an oven to obtain the polyacrylamide layer 3 grown on the polysulfone porous membrane layer 1. The "groove effect" of the cuprous oxide nanoparticle layer 2 is lacking, resulting in a significant decrease in water flux.

[0119] Comparing Example 1 and Comparative Example 7, it can be seen that the desalination rate of Comparative Example 7 is significantly lower. This is because step S2 is omitted in Comparative Example 7, which involves interfacial polymerization on the cuprous oxide nanoparticle layer 2 to form a polyamide layer 4. The sustained-release regulation effect of the polyacrylamide layer 3 on the diamine monomer during the interfacial polymerization to form the polyamide layer 4 is missing. Furthermore, due to the "groove effect" of the cuprous oxide nanoparticle layer 2, the polyamide layer 4 is prone to defects such as looseness and uneven thickness, resulting in a significant decrease in the desalination rate.

[0120] Comparing Example 1 and Comparative Example 8, it can be seen that the water flux of Comparative Example 8 is significantly reduced, and the desalination rate is also slightly lower. This is because steps S1 and S2 are omitted in Comparative Example 8, and the polyamide layer 4 is directly formed by interfacial polymerization on the polysulfone porous membrane layer 1. On the one hand, the "groove effect" of the cuprous oxide nanoparticle layer 2 is missing, and on the other hand, the slow-release regulation effect of the polyacrylamide layer 3 on the diamine monomer during the interfacial polymerization to form the polyamide layer 4 is missing. The resulting polyamide layer 4 is relatively thicker, and the water mass transfer resistance is greater, leading to a significant decrease in water flux. In addition, the adsorption capacity of the polysulfone porous membrane layer 1 for the diamine monomer is lower than that of the polyacrylamide layer 3, so the degree of crosslinking of the resulting polyamide layer 4 is also slightly lower, resulting in a slightly lower desalination rate. Furthermore, in Comparative Example 8, the omission of step S1 avoids the "groove effect" of the cuprous oxide nanoparticle layer 2, which could cause the polyamide layer 4 to break under the test pressure conditions and reduce the desalination rate. That is, compared with Example 1, the desalination rate of Comparative Example 8 is only slightly lower.

[0121] Based on the data in Table 1 and the above analysis, it is evident that the present invention, by using appropriate mass percentages of copper sulfate pentahydrate aqueous solution, acrylamide aqueous solution, and ethylene glycol dimethacrylate in Examples 1-7, can prepare high-performance reverse osmosis membranes with both high water flux and high desalination rate.

[0122] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A method for preparing a high-performance reverse osmosis membrane, characterized in that, include: Step S1: The polysulfone porous membrane layer is subjected to a first immersion treatment in a copper salt aqueous solution with a mass percentage of 0.1%~0.5%, a second immersion treatment in a sodium hydroxide aqueous solution with a pH of 11~12, and a third immersion treatment in an ascorbic acid aqueous solution with a mass percentage of 0.4%~0.6%, to obtain a cuprous oxide nanoparticle layer grown in situ on the polysulfone porous membrane layer, which is the first combined membrane. Step S2: After the first combined membrane is immersed in the reaction solution for the fourth time, the first combined membrane is taken out and then subjected to visible light irradiation to obtain a polyacrylamide layer grown on the cuprous oxide nanoparticle layer in the first combined membrane, thus obtaining the second combined membrane. The reaction solution comprises the following components by mass percentage: 3%–6% acrylamide aqueous solution, 0.1%–0.5% ethylene glycol dimethacrylate, and 1% ascorbic acid; Step S3: The second combined membrane is sequentially immersed in an aqueous solution for a fifth immersion treatment and in an oil phase solution for a sixth immersion treatment. Then, it is dried to obtain a polyamide layer grown on the polyacrylamide layer in the second combined membrane, thus obtaining a high-performance reverse osmosis membrane. The aqueous phase solution comprises a polyamine aqueous solution with a mass percentage of 2% to 5%; the oil phase solution comprises an acyl chloride solution with a mass percentage of 0.08% to 0.15%.

2. The method for preparing the high-performance reverse osmosis membrane as described in claim 1, characterized in that, The copper salt aqueous solution includes an aqueous solution of copper sulfate.

3. The method for preparing the high-performance reverse osmosis membrane as described in claim 1, characterized in that, The copper salt aqueous solution includes copper sulfate pentahydrate aqueous solution.

4. The method for preparing the high-performance reverse osmosis membrane as described in claim 1, characterized in that, The first soaking treatment uses a soaking time of 3-5 minutes and a soaking temperature of 25-30℃; The second soaking treatment uses a soaking time of 5-10 minutes and a soaking temperature of 10-15℃; The third soaking treatment uses a soaking time of 60-90 minutes and a soaking temperature of 65-75℃. The process includes removing excess copper salt aqueous solution from the surface of the polysulfone porous membrane layer using a rubber roller after the first immersion treatment and before the second immersion treatment. The process includes removing excess sodium hydroxide aqueous solution from the surface of the polysulfone porous membrane layer using a rubber roller after the second immersion treatment and before the third immersion treatment. The third soaking treatment also includes washing away excess ascorbic acid aqueous solution from the surface of the polysulfone porous membrane with pure water.

5. The method for preparing the high-performance reverse osmosis membrane as described in claim 1, characterized in that, The fourth soaking treatment uses a soaking time of 3-5 minutes and a soaking temperature of 25-30℃. The visible light irradiation treatment uses an irradiation intensity of 50 mW / cm² and an irradiation time of 5 min; The process includes removing excess reaction solution from the surface of the first composite membrane using a rubber roller after the fourth immersion treatment and before the visible light irradiation treatment.

6. The method for preparing the high-performance reverse osmosis membrane as described in claim 1, characterized in that, The fifth soaking treatment uses a soaking time of 30 seconds and a soaking temperature of 25°C. The sixth soaking treatment uses a soaking time of 10 seconds and a soaking temperature of 25°C. The process includes removing excess polyamine aqueous solution from the surface of the second combined membrane using a rubber roller after the fifth immersion treatment and before the sixth immersion treatment. The polyamine aqueous solution includes an aqueous solution of m-phenylenediamine; the solute used in the oil phase acyl chloride solution includes trimesoyl chloride, and the solvent used includes n-hexane; The drying process uses a drying temperature of 60°C and a drying time of 1 minute.

7. The method for preparing a high-performance reverse osmosis membrane as described in any one of claims 1 to 6, characterized in that, It also includes the preparation of the polysulfone porous membrane layer; specifically, the impurity-removed polysulfone solution is first degassed under vacuum, and then extruded through a slit and uniformly coated onto the substrate; wherein the substrate is pre-fixed on the carrier; then, a porous polysulfone membrane is formed on the substrate through phase transformation, thus obtaining the polysulfone porous membrane layer; The polysulfone solution has a mass percentage of 15% to 18%; The slit width is 100~300μm; The coating amount of the polysulfone solution on the substrate is 0.03~0.06 g / cm³. 2 ; The base layer includes non-woven fabric.

8. The method for preparing the high-performance reverse osmosis membrane as described in claim 7, characterized in that, The parameters used for vacuum degassing include a vacuum degree of -0.095MPa to -0.098MPa, a degassing time of 5 to 6 hours, and a degassing temperature of 25 to 30°C. The phase transformation is carried out by a solidification bath at a temperature of 15°C.

9. A high-performance reverse osmosis membrane, characterized in that, The high-performance reverse osmosis membrane was prepared using the method described in claim 8.

10. The high-performance reverse osmosis membrane as described in claim 9, characterized in that, The high-performance reverse osmosis membrane has a desalination rate of over 99.40% and a water flux of over 110 LMH.

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