High-permeability anti-pollution reverse osmosis membrane based on secondary interfacial polymerization and preparation method thereof

Abstract

The invention provides a high-permeability anti-pollution reverse osmosis membrane based on secondary interfacial polymerization and a preparation method thereof, and belongs to the technical field of reverse osmosis membrane preparation. The preparation method comprises the following steps: dissolving m-phenylenediamine in deionized water, and mixing to obtain a water-phase solution; dissolving trimesoyl chloride in normal hexane to obtain an organic phase solution; coating a polysulfone base membrane with the water phase solution, standing, then coating with the organic phase solution, and carrying out interfacial polymerization reaction to form a polyamide layer, so as to obtain a reverse osmosis membrane I; coating the surface of the reverse osmosis membrane I with an aqueous solution of a linear aliphatic sulfamic acid compound, enabling the aqueous solution of the linear aliphatic sulfamic acid compound and the residual acyl chloride groups to be subjected to secondary interfacial polymerization reaction, and standing to obtain a reverse osmosis membrane II subjected to secondary interfacial polymerization; the reverse osmosis membrane II is placed in a drying oven to be subjected to heat treatment, and the high-permeability anti-pollution reverse osmosis membrane is obtained. The water flux of the reverse osmosis membrane is greatly improved, and meanwhile, a good inhibition effect on organic pollution and inorganic pollution is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of reverse osmosis membrane preparation, and in particular relates to a high-permeability anti-pollution reverse osmosis membrane based on secondary interfacial polymerization and a preparation method thereof. Background Art

[0002] As an advanced water treatment technology, reverse osmosis (RO) has become a leading solution to freshwater shortages and is widely used in seawater desalination and industrial wastewater treatment. As the core of RO technology, the performance of RO membranes is directly related to the economic viability and feasibility of the desalination process. Therefore, the development of high-performance RO membranes is crucial.

[0003] Polyamide reverse osmosis membranes are the most commonly used reverse osmosis membranes due to their excellent selectivity, good stability, and high mechanical strength. Their core performance is primarily determined by the polyamide separation layer. The permeability of a reverse osmosis membrane refers to the ability of water molecules to pass through the membrane under the action of a driving force, and is one of the key indicators for measuring water treatment efficiency and operating costs. Improving the permeability of reverse osmosis membranes helps achieve higher water production at lower operating pressures, thereby reducing energy consumption. However, the inherent dense polyamide separation layer and relatively hydrophobic and rough ridge-like surface structure of reverse osmosis membranes make them subject to serious membrane fouling problems during actual application. This results in a continuous decrease in water flux during reverse osmosis membrane application, increasing the operating and maintenance costs of the system, and the need to improve long-term operational stability. This further highlights the "dual demand" for reverse osmosis membranes for both high permeability and high anti-fouling performance.

[0004] In practical applications, due to the complexity of the influent, reverse osmosis membranes are usually faced with various types of membrane fouling, mainly including organic pollution, inorganic pollution, biological pollution, colloidal pollution and complex pollution, which significantly reduces the performance and service life of the membrane. The process and degree of membrane fouling depend on the interaction between the membrane surface and the pollutants, and this interaction is closely related to the surface properties of the reverse osmosis membrane. Therefore, by adjusting the surface properties of the reverse osmosis membrane, such as increasing the surface hydrophilicity, reducing the roughness, introducing an anti-pollution functional layer, etc., the adhesion of pollutants on the reverse osmosis membrane surface can be significantly weakened, effectively alleviating the membrane fouling problem. Specifically, the hydrophilic membrane surface can form a hydration layer, effectively repelling organic pollutants (such as proteins, lipids, etc.), and significantly reducing the adsorption of organic pollutants on the membrane surface. On the other hand, the hydrophilic membrane surface can distribute water molecules more evenly, reduce local salt concentration, and thus reduce the risk of inorganic salt crystallization and deposition. In addition, the smooth membrane surface has fewer concave-convex structures, which is conducive to reducing the adsorption sites of pollutants on the membrane surface, thereby alleviating the retention and aggregation of pollutants. At the same time, the smooth membrane surface makes it easier to restore membrane performance through simple physical or chemical cleaning methods, which is of great significance for extending the service life of the membrane and improving water treatment efficiency.

[0005] In order to reduce the direct interaction between pollutants and the reverse osmosis membrane surface, membrane surface modification has become a direct and effective method to alleviate reverse osmosis membrane pollution. By forming a thin and uniform anti-pollution layer on the modified membrane surface, direct contact between pollutants and the membrane can be prevented. Currently, most methods use hydrophilic polymer coatings (such as PVA and polydopamine coatings) or grafting hydrophilic macromolecules to increase the hydrophilicity of the membrane surface, thereby resisting the attachment of pollutants to the membrane surface. However, the introduction of the coating often increases additional transmission resistance, resulting in a decrease in the water permeability of the membrane, and there is a risk of loss and leakage of the coating material during the long-term service of the reverse osmosis membrane, which not only causes a loss of anti-pollution performance, but also easily causes secondary pollution to the water body.

[0006] In addition, although the modification of the membrane surface with some hydrophilic substances with rigid structures can improve the hydrophilicity of the membrane surface, after the rigid structure is embedded in the network structure of the polyamide separation layer, it will hinder the construction of water permeation channels, which is often not conducive to the improvement of water permeation performance. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a high-permeability anti-pollution reverse osmosis membrane based on secondary interfacial polymerization and a preparation method thereof.

[0008] To solve the above technical problems, the technical solution adopted by the present invention is: a method for preparing a high permeability anti-fouling reverse osmosis membrane based on secondary interfacial polymerization, comprising the following steps:

[0009] S1. Dissolve m-phenylenediamine in deionized water and mix well to obtain an aqueous phase solution, and dissolve trimesoyl chloride in n-hexane to obtain an organic phase solution;

[0010] S2, coating the aqueous solution of step S1 on a polysulfone-based membrane, removing the residual aqueous solution on the surface after standing, to obtain membrane I, and then coating the organic solution of step S1 on membrane I, forming a polyamide layer after interfacial polymerization reaction, to obtain reverse osmosis membrane I;

[0011] S3, flushing the surface of reverse osmosis membrane I with n-hexane to remove unreacted trimesoyl chloride and residual impurities;

[0012] S4, dissolving a linear aliphatic aminosulfonic acid compound and a small amount of surfactant in deionized water to obtain an aqueous solution of the linear aliphatic aminosulfonic acid compound, and then uniformly coating the aqueous solution of the linear aliphatic aminosulfonic acid compound on the surface of the reverse osmosis membrane I in step S3, so that the aqueous solution undergoes a secondary interfacial polymerization reaction with the acyl chloride groups remaining on the surface of the reverse osmosis membrane I, and after standing, removing the aqueous solution remaining on the surface to obtain a reverse osmosis membrane II after the secondary interfacial polymerization;

[0013] S5. Place the reverse osmosis membrane II in an oven for heat treatment, and rinse repeatedly to obtain a high-permeability, anti-pollution reverse osmosis membrane.

[0014] Furthermore, in step S1, camphorsulfonic acid and triethylamine are added to the aqueous solution.

[0015] Furthermore, in step S1, the mass fraction of m-phenylenediamine in the aqueous solution is 1.5-2.0 wt. %; the mass fraction of camphorsulfonic acid in the aqueous solution is 1.8 wt. %; the mass fraction of triethylamine in the aqueous solution is 1.6 wt. %; and the mass fraction of trimesoyl chloride in n-hexane is 0.1-0.15 wt. %.

[0016] Furthermore, in step S2, the standing time of the aqueous phase solution coated on the polysulfone-based membrane is 30 to 60 seconds; the reaction time of the organic phase solution coated on membrane I for interfacial polymerization reaction is 10 to 30 seconds.

[0017] Furthermore, in step S3, the time for washing the membrane surface with n-hexane is 30 seconds;

[0018] Furthermore, in step S4, the surfactant is sodium lauryl sulfate with a concentration of 0.01 wt.%.

[0019] Furthermore, in step S4, the linear aliphatic aminosulfonic acid compound is one or more of 2-[(2-aminoethyl)amino]ethanesulfonic acid sodium salt, 2-aminoethanol hydrogen sulfate, N-carbamoylmethylethanesulfonic acid, sodium aminosulfate, taurine, and 3-aminopropanesulfonic acid.

[0020] Furthermore, in step S4, the linear aliphatic aminosulfonic acid compound is 2-[(2-aminoethyl)amino]ethanesulfonic acid sodium salt.

[0021] Furthermore, in step S4, the mass fraction of the 2-[(2-aminoethyl)amino]ethanesulfonic acid sodium salt aqueous solution is 0.05 to 0.5 wt.%; the 2-[(2-aminoethyl)amino]ethanesulfonic acid sodium salt aqueous solution is coated on the surface of the reverse osmosis membrane I, and the static reaction time is 2 to 20 minutes.

[0022] Furthermore, in step S5, the heat treatment time in the oven is 5 to 10 minutes and the temperature is 80 to 100°C.

[0023] Another object of the present application is to provide a method for preparing a high permeability anti-fouling reverse osmosis membrane based on secondary interfacial polymerization, and to obtain a high permeability anti-fouling reverse osmosis membrane based on secondary interfacial polymerization.

[0024] The flux recovery rate of the high-permeability anti-pollution reverse osmosis membrane for organic pollution (SDS) is 80.6% to 91.3%, and the flux recovery rate for inorganic pollution (CaSO4) is 89.3% to 96.9%.

[0025] The beneficial effects of the present invention are:

[0026] In view of the problem that the water flux and anti-pollution performance of reverse osmosis membranes need to be improved, the present invention provides a high-permeability anti-pollution reverse osmosis membrane based on secondary interfacial polymerization and a preparation method thereof.

[0027] A compound rich in hydrophilic sulfonic acid groups (–SO3H) and having linear flexible chain segments is grafted onto the surface of the polyamide separation layer. On the one hand, the linear segments containing hydrophilic groups can form a rigid-flexible interpenetrating network with the rigid benzene ring structure in the polyamide layer, thereby constructing continuous water channels, reducing the diffusion resistance of water molecules through the interface, and significantly improving the permeability of the membrane. On the other hand, the strong hydrophilicity and electrostatic repulsion of the sulfonic acid group significantly enhance the hydration capacity and anti-fouling ability of the membrane surface.

[0028] Therefore, after the traditional interfacial polymerization reaction, a hydrophilic and charged flexible chain segment is introduced through a secondary interfacial polymerization reaction, which can form a certain degree of flexible layer on the membrane surface, while improving the hydrophilicity and charge properties and reshaping the surface structure of the reverse osmosis membrane, thereby preparing a highly permeable and anti-fouling reverse osmosis membrane. By introducing the "structural-chemical synergistic effect" at the molecular level, not only the water flux of the reverse osmosis membrane is greatly improved, but also a good inhibitory effect is played on both organic and inorganic pollution. In addition, this preparation method requires a small number of materials and a simple preparation process, providing a new strategy for the design of highly permeable and anti-fouling reverse osmosis membranes.

[0029] Specifically, in the present invention, a secondary interfacial polymerization grafting strategy is adopted. By reacting the amine group in 2-[(2-aminoethyl)amino]ethanesulfonic acid sodium salt with the residual acyl chloride group on the surface of the reverse osmosis membrane, a flexible segment structure is introduced into the membrane surface, increasing the free volume and transmission path inside the polyamide layer, which is conducive to the rapid penetration of water molecules. At the same time, the grafting process can reshape the surface structure of the membrane to form a smooth and thinner selective layer. In addition, the hydrophilic and charged sulfonic acid groups are firmly grafted to the membrane surface in the form of covalent bonds, which helps to regulate the chemical properties of the membrane surface. The synergistic effect of the two makes the prepared reverse osmosis membrane have a higher permeability while achieving a significant improvement in anti-pollution performance against both organic and inorganic pollution. Compared with traditional reverse osmosis membranes, the reverse osmosis membrane prepared by the present invention optimizes the network structure of the polyamide layer and forms a smooth, hydrophilic and charged membrane surface, which greatly improves the water permeability of the reverse osmosis membrane (the water flux can be increased by up to 183.3%), and improves the dual ability of the reverse osmosis membrane to resist organic and inorganic pollution. Under the conditions of pollution by typical organic pollutants sodium alkyl sulfate (SDS) and typical inorganic pollutants calcium sulfate (CaSO4), the flux recovery rates reached 91.3% and 96.9%, respectively, which has good application value and promotion prospects.

[0030] In summary, the secondary interfacial polymerization reaction of a flexible segment structure containing reactive amine and hydrophilic sulfonic acid groups with unreacted acyl chloride groups on the membrane surface optimizes the surface properties of the reverse osmosis membrane, effectively avoiding the additional resistance introduced by the surface coating and the complex grafting reaction process. The introduction of the flexible segment structure reshapes the surface structure of the reverse osmosis membrane, making it smoother and thinner. It also increases the free volume and diffusion pathways within the membrane separation layer, facilitating the rapid permeation of water molecules and significantly improving the permeation flux of the reverse osmosis membrane. Furthermore, the introduced sodium sulfonate (–SO₃H) and amine (–NH₂) groups are both highly hydrophilic and can adsorb and stabilize a layer of water molecules on the membrane surface, forming a hydration barrier. Furthermore, the sulfonic acid groups have a strong electronegativity, which can reduce the adsorption of pollutants on the membrane surface through the hydration barrier and electrostatic interactions. Furthermore, the flexible segment structure provides a dynamic buffer layer on the membrane surface, further reducing pollutant accumulation.

[0031] The preparation method of the present invention is simple and easy to control. It can effectively regulate the hydrophilicity and charge density of the membrane surface while reshaping the microstructure of the reverse osmosis membrane surface and the network structure of the polyamide layer. Through the synergistic effect of surface structure and chemical properties, the permeation flux of the reverse osmosis membrane is effectively improved, while the deposition of pollutants on the membrane surface is reduced, and the anti-pollution ability of the reverse osmosis membrane against organic and inorganic pollution is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The present invention will be described in detail below with reference to the accompanying drawings and in combination with examples, and the advantages and implementation modes of the present invention will become more apparent. The contents shown in the accompanying drawings are only used to illustrate the present invention and do not constitute any limitation to the present invention. In the accompanying drawings:

[0033] Figure 1 It is a scanning electron microscope image of the cross section of the reverse osmosis membrane prepared in the comparative example of the present invention.

[0034] Figure 2 This is a scanning electron microscope image of the cross section of the high permeability anti-pollution reverse osmosis membrane prepared in Example 1 of the present invention.

[0035] Figure 3 It is a scanning electron microscope image of the reverse osmosis membrane surface prepared in the comparative example of the present invention.

[0036] Figure 4 This is a graph showing the surface roughness of a reverse osmosis membrane prepared in a comparative example of the present invention.

[0037] Figure 5 This is a scanning electron microscope image of the surface of the high-permeability anti-pollution reverse osmosis membrane prepared in Example 1 of the present invention.

[0038] Figure 6 This is a surface roughness diagram of the high permeability anti-pollution reverse osmosis membrane prepared in Example 1 of the present invention.

[0039] Figure 7 This is a scanning electron microscope image of the surface of the high-permeability anti-pollution reverse osmosis membrane prepared in Example 6 of the present invention.

[0040] Figure 8 This is a surface roughness diagram of the high permeability anti-pollution reverse osmosis membrane prepared in Example 6 of the present invention. DETAILED DESCRIPTION

[0041] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below in conjunction with the best embodiment.

[0042] The preparation method of a high-permeability anti-fouling reverse osmosis membrane based on secondary interfacial polymerization comprises the following steps:

[0043] S1, dissolving m-phenylenediamine, camphorsulfonic acid and triethylamine in deionized water, mixing well to obtain an aqueous phase solution, and dissolving trimesoyl chloride in n-hexane to obtain an organic phase solution;

[0044] S2, coating the aqueous solution of step S1 on a polysulfone-based membrane, removing the residual aqueous solution on the surface after standing, to obtain membrane I, and then coating the organic solution of step S1 on membrane I, forming a polyamide layer after interfacial polymerization reaction, to obtain reverse osmosis membrane I;

[0045] S3, using n-hexane to rinse the unreacted trimesoyl chloride and residual impurities on the surface of reverse osmosis membrane I (because there are three acyl chloride groups on a trimesoyl chloride monomer, this step removes the monomers in which all three groups have not reacted);

[0046] S4, 2-[(2-aminoethyl) amino] ethanesulfonic acid sodium salt and a small amount of sodium lauryl sulfate (concentration of 0.01wt.%) were dissolved in deionized water to obtain an aqueous solution of 2-[(2-aminoethyl) amino] ethanesulfonic acid sodium salt, and then the aqueous solution of 2-[(2-aminoethyl) amino] ethanesulfonic acid sodium salt was uniformly coated on the surface of the reverse osmosis membrane I in step S3, so that it and the acyl chloride groups remaining on the surface of the reverse osmosis membrane I underwent secondary interfacial polymerization reaction, and after standing, the residual aqueous solution on the surface was removed to obtain a reverse osmosis membrane II after secondary interfacial polymerization;

[0047] S5. Place the reverse osmosis membrane II in an oven for heat treatment, and rinse repeatedly to obtain a high-permeability, anti-pollution reverse osmosis membrane.

[0048] In step S1, the mass fraction of m-phenylenediamine in the aqueous solution is 1.5-2.0 wt.%, preferably 1.5 wt.%; the mass fraction of trimesoyl chloride in n-hexane is 0.1-0.15 wt.%, preferably 0.1 wt.%.

[0049] In step S1, camphorsulfonic acid and triethylamine are further added to the aqueous solution as acid receivers, wherein the mass fraction of camphorsulfonic acid in the aqueous solution is 1.8 wt.%, and the mass fraction of triethylamine in the aqueous solution is 1.6 wt.%.

[0050] In step S2, the aqueous solution coated on the polysulfone-based membrane is allowed to stand for 30 to 60 seconds, preferably 30 seconds.

[0051] In step S2, the organic phase solution is coated on membrane I to undergo interfacial polymerization reaction for a reaction time of 10 to 30 seconds, preferably 30 seconds.

[0052] In step S3, the membrane surface is rinsed with n-hexane for 30 s;

[0053] In step S4, the mass fraction of the 2-[(2-aminoethyl)amino]ethanesulfonic acid sodium salt aqueous solution is 0.05-0.5 wt.%; the 2-[(2-aminoethyl)amino]ethanesulfonic acid sodium salt aqueous solution is coated on the surface of the reverse osmosis membrane I, and the static reaction time is 2-20 minutes.

[0054] Preferably, the mass fraction of the 2-[(2-aminoethyl)amino]ethanesulfonic acid sodium salt aqueous solution is 0.05-0.2 wt.%; the 2-[(2-aminoethyl)amino]ethanesulfonic acid sodium salt aqueous solution is coated on the surface of the reverse osmosis membrane I and the static reaction time is 5-15 minutes.

[0055] In step S5, the heat treatment in the oven is performed for 5 to 10 minutes, preferably 8 minutes, at a temperature of 80 to 100°C.

[0056] Another object of the present application is to provide a method for preparing a high permeability anti-fouling reverse osmosis membrane based on secondary interfacial polymerization, and to obtain a high permeability anti-fouling reverse osmosis membrane based on secondary interfacial polymerization.

[0057] The flux recovery rate of the obtained high-permeability anti-pollution reverse osmosis membrane for organic pollution (SDS) is 80.6% to 91.3%, and the flux recovery rate for inorganic pollution (CaSO4) is 89.3% to 96.9%.

[0058] Using secondary interfacial polymerization technology, linear aliphatic aminosulfonic acid compounds with reactive amino groups and hydrophilic sulfonic acid groups are grafted onto the surface of reverse osmosis membranes. This effectively improves the membrane's hydrophilicity, charge characteristics, flux stability, and anti-fouling capabilities, thereby enhancing water purification efficiency. This technology has broad application in the preparation of reverse osmosis membranes for seawater and brackish water desalination, industrial wastewater treatment, and ultrapure water production.

[0059] The main raw materials used in the following examples and comparative examples are as follows:

[0060] Polysulfone-based membrane was purchased from Jiangsu Qicheng Purification Technology Co., Ltd.

[0061] m-phenylenediamine (MPD), 99%, was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0062] Trimesoyl chloride (TMC), 98%, was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0063] n-Hexane, >98%, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0064] Sodium dodecyl sulfate (SDS), 98%, was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0065] Camphorsulfonic acid (CSA), >98%, purchased from Tokyo Chemical Industry Development Co., Ltd. (Shanghai);

[0066] Sodium chloride (NaCl), analytical grade, was purchased from Tianjin Kemeiou Chemical Reagent Co., Ltd.;

[0067] Sodium sulfate (Na2SO4), analytical grade, was purchased from Tianjin Kemeiou Chemical Reagent Co., Ltd.;

[0068] Calcium chloride (CaCl2), analytical grade, was purchased from Tianjin Kemeiou Chemical Reagent Co., Ltd.;

[0069] Triethylamine (TEA), 99%, was purchased from Tianjin Kemeiou Chemical Reagent Co., Ltd.;

[0070] 2-[(2-Aminoethyl)amino]ethanesulfonic acid sodium salt (AAS), 50% aqueous solution, was purchased from Shanghai Yien Chemical Technology Co., Ltd.

[0071] The main equipment used in the following examples and comparative examples are as follows:

[0072] The medium-pressure cross-flow test device for evaluating the performance of reverse osmosis membranes was purchased from Hangzhou Saifei Membrane Separation Technology Co., Ltd.

[0073] Conductivity meter, DDSJ-307F, purchased from Shanghai Oushituoer Industrial Co., Ltd.

[0074] Atomic force microscope, Icon, Bruker, USA;

[0075] Fully automatic contact angle measuring instrument, DSA30S, KRUSS, Germany;

[0076] Solid surface zeta potential instrument, SURPASS-3, Anton Paar, Austria;

[0077] Thermal field emission scanning electron microscope, GeminiSEM 500, Carl Zeiss, UK.

[0078] The reverse osmosis membrane performance test method is as follows:

[0079] (1) Reverse osmosis membrane water flux and desalination rate:

[0080] The permeability and selectivity of the reverse osmosis membrane were evaluated by water flux and salt rejection (sodium chloride). The feed liquid used was a 2g / L NaCl aqueous solution, the test pressure was 1.55MPa, and the cross-flow rate was 80L·m -2 ·h -1 , the temperature is 25℃; water flux (J) refers to the volume of permeate permeated per unit area per unit time, as shown in the following formula:

[0081]

[0082] Where J represents water flux (L·m -2 ·h -1 ), V is the permeation volume of pure water (L), A is the effective permeation area (m 2 ), △t is the penetration time (h).

[0083] Under the same conditions as above, the calculation method of salt rejection (R) is as follows:

[0084]

[0085] Where C f and C p (μS / cm) represents the conductivity of feed water and product water respectively.

[0086] (2) Anti-pollution performance of reverse osmosis membrane:

[0087] The flux decay and recovery rates of reverse osmosis membranes were tested using sodium dodecyl sulfate (SDS) and calcium sulfate (CaSO4) as typical organic and inorganic pollutants to evaluate the membrane's anti-fouling performance and its changes. For the organic contamination test, an aqueous solution containing 2 g / L NaCl and 0.2 g / L SDS was used as the feed solution, with a pH of 7.0 ± 0.5. For the inorganic contamination test, an aqueous solution containing 2 g / L NaCl, 20 mM Na2SO4, and 20 mM CaCl2 was used as the feed solution, with a pH of 6.5 ± 0.5. The contamination run time was 8 hours. The flux decay rate was expressed as the ratio ((J0-J) / J0) of the difference between the initial equilibrium flux (J0) and the instantaneous flux (J) of the reverse osmosis membrane at 25°C and 1.55 MPa to the initial equilibrium flux (J0).

[0088] After the contamination is completed, the feed liquid is replaced with clean water, and the reverse osmosis membrane is cleaned in situ for 0.5 hours. The permeation flux of the reverse osmosis membrane is measured again to obtain the recovery flux (J1). The flux recovery rate is expressed as the ratio (J1 / J0) of the recovery flux (J1) after cleaning to the initial equilibrium flux (J0).

[0089] Example 1:

[0090] The preparation method of a high-permeability anti-fouling reverse osmosis membrane based on secondary interfacial polymerization comprises the following steps:

[0091] S1. Using interfacial polymerization, m-phenylenediamine, camphorsulfonic acid, and triethylamine were dissolved in deionized water and mixed to obtain an aqueous solution containing 1.5 wt.% of m-phenylenediamine, 1.8 wt.% of camphorsulfonic acid, and 1.6 wt.% of triethylamine. Trimesoyl chloride was dissolved in n-hexane to obtain an organic solution containing 0.1 wt.% of trimesoyl chloride.

[0092] S2, coating the aqueous phase solution of step S1 on a polysulfone-based membrane, allowing it to stand for 30 seconds, and then purging with nitrogen to completely remove the residual aqueous phase solution on the surface to obtain membrane I, and then coating the organic phase solution of step S1 on membrane I, allowing it to stand for 30 seconds and then be removed, so that an interfacial polymerization reaction occurs to form a polyamide layer to obtain reverse osmosis membrane I;

[0093] S3, washing the membrane surface with n-hexane for 30 seconds to remove unreacted trimesoyl chloride and residual impurities;

[0094] S4, 0.1wt.% of 2-[(2-aminoethyl)amino]ethanesulfonic acid sodium salt and 0.01wt.% of sodium lauryl sulfate are completely dissolved in deionized water to obtain an aqueous solution of 2-[(2-aminoethyl)amino]ethanesulfonic acid sodium salt, and then the aqueous solution of 2-[(2-aminoethyl)amino]ethanesulfonic acid sodium salt is uniformly coated on the surface of the reverse osmosis membrane I in step S2, so that it undergoes a secondary interfacial polymerization reaction with the acyl chloride groups remaining on the surface of the reverse osmosis membrane I, and after standing for 10min, the residual aqueous solution on the surface is removed to obtain a reverse osmosis membrane II after secondary interfacial polymerization;

[0095] S5. Place the reverse osmosis membrane II in an oven at 100° C. for heat treatment for 8 minutes, and rinse it repeatedly with pure water to obtain a high-permeability anti-pollution reverse osmosis membrane.

[0096] Example 2:

[0097] The only difference from Example 1 is that in step S4, the standing time of the secondary interfacial polymerization reaction is 15 minutes, and the other conditions remain unchanged.

[0098] Example 3:

[0099] The only difference from Example 2 is that in step S4, the mass concentration of the 2-[(2-aminoethyl)amino]ethanesulfonic acid sodium salt aqueous solution is 0.05 wt.%, and the other conditions remain unchanged.

[0100] Example 4:

[0101] The only difference from Example 2 is that in step S4, the mass concentration of the 2-[(2-aminoethyl)amino]ethanesulfonic acid sodium salt aqueous solution is 0.2 wt.%, and the other conditions remain unchanged.

[0102] Example 5:

[0103] The only difference from Example 4 is that in step S4, the standing time of the secondary interfacial polymerization reaction is 5 minutes, and the other conditions remain unchanged.

[0104] Example 6:

[0105] The only difference from Example 4 is that in step S4, the standing time of the secondary interfacial polymerization reaction is 10 minutes, and the other conditions remain unchanged.

[0106] Example 7:

[0107] The only difference from Example 3 is that in step S4, the standing time of the secondary interfacial polymerization reaction is 5 minutes, and the other conditions remain unchanged.

[0108] Example 8:

[0109] The only difference from Example 3 is that in step S4, the standing time of the secondary interfacial polymerization reaction is 10 minutes, and the other conditions remain unchanged.

[0110] Example 9:

[0111] The only difference from Example 1 is that in step S4, the standing time of the secondary interfacial polymerization reaction is 5 minutes, and the other conditions remain unchanged.

[0112] Example 10:

[0113] The only difference from Example 1 is that in step S1, the mass concentration of m-phenylenediamine is 2.0 wt.%, and the other conditions remain unchanged.

[0114] Comparative Example:

[0115] The only difference from Example 1 is that steps S3 and S4 are not included, and after obtaining reverse osmosis membrane I in step S2, reverse osmosis membrane I is placed in an oven at 100° C. for 8 minutes and repeatedly washed with pure water to obtain a reverse osmosis membrane.

[0116] The amounts of raw materials added and the reaction times for the above Examples 1 to 10 and Comparative Examples are shown in Table 1.

[0117] Table 1 Amount of raw materials added and reaction time in each embodiment and comparative example

[0118]

[0119] The performance tests were conducted on the high permeability anti-fouling reverse osmosis membranes prepared in Examples 1 to 10 and the reverse osmosis membrane prepared in the comparative example. The results are shown in Table 2.

[0120] Table 2 High permeability anti-fouling reverse osmosis membrane and reverse osmosis membrane structure and performance test results

[0121]

[0122] Sodium 2-[(2-aminoethyl)amino]ethanesulfonic acid salt is an aliphatic hydrophilic linear small molecule compound with both polyamine functional groups and sodium sulfonate groups. It can be covalently linked to the polyamide layer through its terminal amine group and introduced into the membrane surface. The introduction of a flexible chain segment structure can reshape the surface structure of the reverse osmosis membrane, making the membrane surface smoother and thinner, while increasing the free volume and diffusion path inside the membrane separation layer, which is conducive to the rapid penetration of water molecules. In addition, the sulfonic acid group of this molecular structure can effectively improve the hydrophilicity and negative charge of the membrane surface, enhancing its anti-pollution performance. At the same time, the flexible chain segment helps to construct a water channel structure with a spatial repulsion effect, which is an ideal building block for achieving rigid-flexible synergistic anti-pollution modification.

[0123] From the data in Table 2, it can be seen that the water flux of the high permeability and anti-fouling reverse osmosis membrane obtained after the secondary interfacial polymerization reaction of 2-[(2-aminoethyl)amino]ethanesulfonic acid sodium salt on the surface of reverse osmosis membrane I was significantly improved. Compared with the water flux of the comparative example (49.2 L·m -2 ·h -1 ), the water flux of Examples 1 to 10 was increased to 69.6-90.2 L·m -2 ·h -1 The results indicate that sodium salt of 2-[(2-aminoethyl)amino]ethanesulfonic acid has great advantages in improving the water permeability of reverse osmosis membranes.

[0124] In addition, the smaller the membrane flux attenuation rate after the pollution experiment or the larger the flux recovery rate, the better the anti-pollution performance of the reverse osmosis membrane. The reverse osmosis membranes modified by the secondary interfacial polymerization of 2-[(2-aminoethyl)amino]ethanesulfonic acid sodium salt of the present invention all show excellent anti-pollution ability. Among them, in the organic pollution experiment, the flux attenuation rate of Examples 1 to 10 after pollution was 19.8% to 36.3%, which was significantly lower than the initial reverse osmosis membrane (42.7%) without secondary interfacial polymerization in the comparative example. This shows that the high permeability anti-pollution reverse osmosis membrane prepared by the present invention can effectively reduce the interaction between the membrane surface and pollutants, thereby reducing the adsorption and deposition of pollutants on its surface. In addition, after cleaning, the flux recovery rate of Examples 1 to 10 can reach 80.6% to 91.3%, while the flux recovery rate of the comparative example is only 72.9%. The high recovery rate of membrane flux shows that the modified membrane is easier to be cleaned after pollution, which is conducive to the recovery of membrane performance. Similar to the above results, in the inorganic contamination experiment, the flux attenuation rate of Examples 1 to 10 decreased from 33.3% (Comparative Example) to 20.0%-29.1%, and the flux recovery rate after cleaning increased from 89.0% (Comparative Example) to 89.3%-96.9%. These results demonstrate that the modification method of the present invention, which combines rigid-flexible structure with chemical properties, can construct a high-permeability reverse osmosis membrane while significantly improving the membrane's resistance to organic and inorganic contamination.

[0125] The reasons for the above changes can be explained as follows: As shown in Table 2, the water contact angle of the membrane surface after the secondary interfacial polymerization is significantly reduced, indicating that the hydrophilicity of the membrane surface is significantly improved. Figure 1 and Figure 2 As shown in the figure, compared with the comparative example, the membrane thickness of Example 1 is significantly reduced and the smoothness is significantly improved. This shows that the polyamide layer modified with a linear aliphatic structure has a lower membrane thickness and a smoother surface. The synergistic effect of surface hydrophilicity and membrane thickness can effectively reduce water transmission resistance. At the same time, the constructed rigid-flexible interpenetrating structure can show obvious advantages in improving water flux, ultimately significantly improving flux.

[0126] As shown in Table 2, the comparative example has lower hydrophilicity and charge properties and higher surface roughness, which will make the membrane vulnerable to organic and inorganic contamination. Figures 3 to 6 As shown, compared with the comparative example, the morphology of the high permeability and anti-pollution reverse osmosis membrane prepared in Example 1 has undergone significant changes. The secondary interfacial polymerization reaction initiated by 2-[(2-aminoethyl)amino]ethanesulfonic acid sodium salt can significantly reduce the roughness of the membrane surface, and the smooth membrane surface constructed can greatly reduce the deposition of pollutants on the membrane surface; at the same time, due to the introduction of sulfonic acid groups, the hydrophilicity and negative charge density of the reverse osmosis membrane are significantly enhanced, and the synergistic effect of the resulting hydration layer barrier and electrostatic repulsion effectively improves the ability of the reverse osmosis membrane to resist organic and inorganic pollution at the same time.

[0127] In addition, the surface properties and membrane performance of the obtained membrane are closely related to the concentration of the grafted material and the grafting time. As shown in Table 2, as the concentration of 2-[(2-aminoethyl)amino]ethanesulfonic acid sodium salt increases, the surface hydrophilicity and negative charge density continue to increase. However, as Figure 7 and Figure 8 As shown in the figure, when the grafting concentration is greater than 0.2 wt.% or the reaction time is greater than 20 min, the relatively vigorous secondary polymerization reaction will lead to a decrease in structural uniformity and a decrease in salt rejection. Therefore, within a certain concentration and time range, the secondary interfacial polymerization reaction of 2-[(2-aminoethyl)amino]ethanesulfonic acid sodium salt can not only significantly improve the membrane flux, but also simultaneously enhance the membrane's resistance to organic and inorganic fouling.

[0128] The 2-[(2-aminoethyl)amino]ethanesulfonic acid sodium salt in all the above examples and comparative examples can be replaced with 2-aminoethanol hydrogen sulfate, N-carbamoylmethylethanesulfonic acid, sodium sulfamate, taurine, or 3-aminopropanesulfonic acid to achieve the above results. The present invention is described using 2-[(2-aminoethyl)amino]ethanesulfonic acid sodium salt as an example.

[0129] The embodiments of the present invention are described in detail above, but the contents are only preferred embodiments of the present invention and should not be considered to limit the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the present invention.

Claims

1. A method for preparing a high-permeability anti-pollution reverse osmosis membrane based on secondary interfacial polymerization, characterized in that: The following steps are involved: S1. Dissolve m-phenylenediamine in deionized water and mix well to obtain an aqueous phase solution, and dissolve trimesoyl chloride in n-hexane to obtain an organic phase solution; S2, coating the aqueous solution of step S1 on a polysulfone-based membrane, removing the residual aqueous solution on the surface after standing, to obtain membrane I, and then coating the organic solution of step S1 on membrane I, forming a polyamide layer after interfacial polymerization reaction, to obtain reverse osmosis membrane I; S3, flushing the surface of reverse osmosis membrane I with n-hexane to remove unreacted trimesoyl chloride and residual impurities; S4, dissolving a linear aliphatic aminosulfonic acid compound and a surfactant in deionized water to obtain an aqueous solution of the linear aliphatic aminosulfonic acid compound, and then uniformly coating the aqueous solution of the linear aliphatic aminosulfonic acid compound on the surface of the reverse osmosis membrane I in step S3, causing the aqueous solution to undergo a secondary interfacial polymerization reaction with the acyl chloride groups remaining on the surface of the reverse osmosis membrane I, and after standing, removing the aqueous solution remaining on the surface to obtain a reverse osmosis membrane II after the secondary interfacial polymerization; S5. Place the reverse osmosis membrane II in an oven for heat treatment, and rinse repeatedly to obtain a high-permeability, anti-pollution reverse osmosis membrane.

2. The method for preparing a high permeability anti-pollution reverse osmosis membrane based on secondary interfacial polymerization according to claim 1, characterized in that: In step S1, camphorsulfonic acid and triethylamine are further added to the aqueous solution.

3. The method for preparing a high permeability anti-pollution reverse osmosis membrane based on secondary interfacial polymerization according to claim 1, characterized in that: In step S1, the mass fraction of the m-phenylenediamine in the aqueous solution is 1.5-2.0 wt. %; the mass fraction of the trimesoyl chloride in n-hexane is 0.1-0.15 wt. %.

4. The method for preparing a high permeability anti-pollution reverse osmosis membrane based on secondary interfacial polymerization according to claim 1, characterized in that: In step S2, the aqueous phase solution is coated on the polysulfone-based membrane and allowed to stand for 30 to 60 seconds; the organic phase solution is coated on the membrane I and reacts for 10 to 30 seconds to undergo interfacial polymerization.

5. The method for preparing a high permeability anti-pollution reverse osmosis membrane based on secondary interfacial polymerization according to claim 1, characterized in that: In step S4, the linear aliphatic aminosulfonic acid compound is one or more of 2-[(2-aminoethyl)amino]ethanesulfonic acid sodium salt, 2-aminoethanol hydrogen sulfate, N-carbamoylmethylethanesulfonic acid, sodium aminosulfate, taurine, and 3-aminopropanesulfonic acid.

6. The method for preparing a high permeability anti-pollution reverse osmosis membrane based on secondary interfacial polymerization according to claim 5, characterized in that: In step S4, the linear aliphatic aminosulfonic acid compound is 2-[(2-aminoethyl)amino]ethanesulfonic acid sodium salt.

7. The method for preparing a high permeability anti-pollution reverse osmosis membrane based on secondary interfacial polymerization according to claim 6, characterized in that: In step S4, the mass fraction of the 2-[(2-aminoethyl)amino]ethanesulfonic acid sodium salt aqueous solution is 0.05-0.5 wt.%; the 2-[(2-aminoethyl)amino]ethanesulfonic acid sodium salt aqueous solution is coated on the surface of the reverse osmosis membrane I, and the static reaction time is 2-20 minutes.

8. The method for preparing a high permeability anti-pollution reverse osmosis membrane based on secondary interfacial polymerization according to claim 1, characterized in that: In step S5, the heat treatment time in the oven is 5 to 10 minutes and the temperature is 80 to 100°C.

9. A high permeability anti-pollution reverse osmosis membrane, characterized by: The membrane is prepared by the method for preparing a high permeability anti-fouling reverse osmosis membrane based on secondary interfacial polymerization according to any one of claims 1 to 8.

10. The high permeability anti-pollution reverse osmosis membrane according to claim 9, characterized in that: The flux recovery rate for organic pollution is 80.6% to 91.3%, and the flux recovery rate for inorganic pollution is 89.3% to 96.9%.

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