阅读说明：本技术 一种大通量反渗透膜及其制备方法和应用 (Large-flux reverse osmosis membrane and preparation method and application thereof ) 是由 许胜杰 赵伟国 孙家宽 于 2019-11-05 设计创作，主要内容包括：本发明公开了一种大通量反渗透膜的制备方法及其应用。该反渗透膜包括多孔支撑膜和形成于支撑膜上的聚酰胺层,所述聚酰胺层由含多官能胺单体的水相溶液和多元酰基卤的有机相性溶液通过界面聚合反应制备。所述的多官能胺水相溶液中含有0.001～3.0wt％的B族水溶性维生素。本方法制备的反渗透膜在保持较高脱盐率的基础上,具有更高的水通量,在工业给水、废水回用等水处理领域具有较好的应用前景。(The invention discloses a preparation method and application of a high-flux reverse osmosis membrane. The reverse osmosis membrane comprises a porous support membrane and a polyamide layer formed on the support membrane, wherein the polyamide layer is prepared by an interfacial polymerization reaction of an aqueous phase solution containing a polyfunctional amine monomer and an organic phase solution of a polybasic acyl halide. The multifunctional amine aqueous phase solution contains 0.001-3.0 wt% of B-group water-soluble vitamins. The reverse osmosis membrane prepared by the method has higher water flux on the basis of keeping higher desalination rate, and has better application prospect in the water treatment fields of industrial water supply, wastewater reuse and the like.)

1. The large-flux reverse osmosis membrane comprises a support membrane and a polyamide layer formed on the support membrane, and is characterized in that the polyamide layer is doped with B-group water-soluble vitamins.

2. The high flux reverse osmosis membrane of claim 1, wherein said group B water soluble vitamins include one or more of vitamin B1, vitamin B2, vitamin B6, vitamin B8, vitamin B12;

preferably, the vitamin B1 comprises thiamine pyrophosphate, the vitamin B2 comprises riboflavin and its phosphate, the vitamin B6 comprises pyridoxamine and its salts, the vitamin B8 comprises 5' -adenylic acid;

the B-group water-soluble vitamin is preferably thiamine pyrophosphate, riboflavin sodium phosphate, pyridoxamine dihydrochloride, 5' -adenylic acid and vitamin B12.

3. A large flux reverse osmosis membrane according to any one of claims 1-2, wherein said polyamide layer is formed by an interfacial polycondensation reaction between an aqueous polyfunctional amine solution containing a group B water-soluble vitamin and an organic phase solution containing a polybasic acid halide;

wherein, in the aqueous phase solution, the mass percentage of the B-group water-soluble vitamin is 0.001-3.0 wt%, preferably 0.01-1.0 wt%.

4. A large flux reverse osmosis membrane according to claim 3 wherein said polyfunctional amine is an amine containing at least two primary amine groups, including aromatic and aliphatic amines; the aromatic amine comprises phenylenediamine and xylylenediamine which are bonded on a benzene ring in ortho, meta and para positions, and 1,3, 5-triaminobenzene, and the aliphatic amine comprises ethylenediamine, propylenediamine and piperazine; the polyfunctional amine is more preferably m-phenylenediamine; preferably, the mass percent of the polyfunctional amine in the aqueous phase solution is 1.0-10.0 wt%, and more preferably 1.5-6.0 wt%.

5. The high flux reverse osmosis membrane of claim 3 or 4, wherein said aqueous solution further comprises an acid acceptor; the acid acceptor comprises weak base, or a buffer pair consisting of the weak base and acid, or hydroxide, carbonate and bicarbonate of alkali metal, and organic compound; the weak base comprises triethylamine and sodium phosphate; the buffer pair comprises triethylamine hydrochloride and triethylamine camphorsulfonate; the hydroxide, carbonate and bicarbonate of alkali metal include sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate and potassium bicarbonate, and the organic compound includes tetramethylammonium hydroxide and tetraethylammonium hydroxide; the acid acceptor is preferably triethylamine camphorsulfonate;

preferably, the aqueous phase solution contains 1.1-3.5 wt% of triethylamine and 2.3-6.5 wt% of camphorsulfonic acid, and the pH value of the aqueous phase after the triethylamine camphorsulfonate is preferably 9-12.

6. A large flux reverse osmosis membrane according to any one of claims 3-5 wherein said polybasic acid halide comprises an aromatic and/or aliphatic polybasic acid halide, said aromatic polybasic acid halide comprises trimesoyl chloride, terephthaloyl chloride, naphthaloyl chloride, said aliphatic polybasic acid halide comprises adipoyl chloride, cyclopropane tricarboxy chloride, tetrahydrofuran dicarboxy chloride, said polybasic acid halide more preferably trimesoyl chloride;

preferably, the concentration of the polybasic acyl halide in the organic phase solution is 0.01-10.0 wt%, more preferably 0.05-3.0 wt%.

7. The high flux reverse osmosis membrane of any one of claims 3-6, wherein the organic phase solution further comprises a complexing agent, wherein the complexing agent is a trialkyl phosphate, preferably tributyl phosphate; the concentration of the complexing agent is preferably 0.01-1.0 wt%.

8. The method of preparing a high flux reverse osmosis membrane according to any one of claims 1-7 comprising the steps of:

(1) preparation of aqueous phase solution: dissolving polyfunctional amine, triethylamine, camphorsulfonic acid and B-group water-soluble vitamins in water, and uniformly mixing to obtain a polyfunctional amine aqueous phase solution containing the B-group water-soluble vitamins;

(2) and (3) contacting the support membrane with a polyfunctional amine aqueous phase solution containing B-group water-soluble vitamins, removing the surface redundant aqueous phase solution, contacting with an organic phase solution containing polybasic acyl halide, and then carrying out heat treatment to obtain the reverse osmosis membrane.

9. The method according to claim 8, wherein in the step (2), the support membrane can be contacted with the aqueous phase solution on one side or two sides for 0.1-10 minutes, preferably 0.5-3 minutes; the contact temperature is 10-50 ℃, and preferably 15-35 ℃;

the temperature of the organic phase solution is preferably within the range of 20-60 ℃, and more preferably within the range of 25-50 ℃;

the heat treatment temperature is preferably 40-130 ℃, more preferably 60-110 ℃, and the heat treatment time is preferably 1-15 minutes, more preferably 2-10 minutes.

10. Use of a reverse osmosis membrane according to any one of claims 1 to 7 or produced by the production process according to any one of claims 8 to 9 in a water treatment module, a device and/or in a water treatment process.

Technical Field

The invention relates to the technical field of water treatment, in particular to a high-flux reverse osmosis membrane and a preparation method and application thereof.

Background

The reverse osmosis membrane can be used for separating various fluids, the most widely used reverse osmosis membrane at present is a cross-linked aromatic polyamide reverse osmosis membrane, and a polyamide layer is formed by performing interfacial polycondensation reaction on the surface of a porous polysulfone support membrane by using m-phenylenediamine and trimesoyl chloride. The polyamide layer obtained by the reaction is the key to influence the water permeability and the salt retardation. Therefore, it has been the subject of many researchers to optimize a polyamide layer in order to obtain a reverse osmosis membrane having a large flux and a high salt rejection rate by focusing attention on an interfacial polycondensation reaction.

With the rapid development of reverse osmosis membrane technology and the deep use of membrane elements, the development and preparation of large-flux reverse osmosis membranes are gradually the focus of research. The large flux means that the energy consumption required for treating the liquid with the same volume is low, so that the investment and the equipment operation cost can be effectively saved, and the treatment efficiency is improved. In order to achieve the performance of a reverse osmosis membrane with a large flux, the currently published patents and literature mainly go around the optimization of a porous support membrane and the optimization of a polyamide layer. Particularly, the optimization of the polyamide layer is researched more, and the addition of different additives into the aqueous phase solution or the organic phase solution is mostly focused on influencing the interfacial polycondensation process to improve the structure of the polyamide layer so as to improve the flux.

Patents US5254261 and US6171497 increase the water flux of the composite membrane by adding amine salt and isopropanol into the polyamine aqueous phase solution; patent US687827 enhanced water flux by adding a phosphorus-containing complexing agent to the organic phase solution; similarly, US6024873, US5989426, US5843351 and US5576057 are prepared by adding to the aqueous or organic phase solution a solubility parameter ranging from 8 to 14 (cal/cm) ³) ^1/2The alcohol, ether, ketone, ester, nitrogen-containing compound, sulfur-containing compound, etc. to achieve the improvement of water flux.

Besides adding organic small molecules into the water phase or organic phase solution, the water flux can be improved by adding inorganic nano particles. Patent CN101791522 discloses a hybrid reverse osmosis membrane composite membrane of carbon nanotubes, which greatly improves the flux of the membrane while maintaining the desalination rate of the reverse osmosis membrane by adding carbon nanotubes into the aqueous phase or organic phase solution. Similarly, patent CN102114392 and patent CN105080358 disclose that a large increase of water flux is achieved by doping nano zeolite molecular sieve and attapulgite during interfacial polymerization.

Although some technical solutions for improving the water flux of the reverse osmosis membrane have been formed in the prior art, the technical solutions have certain problems in the application process. If a small molecular organic matter is added in the interfacial polymerization process, although the flux can be improved, the salt rejection rate is seriously reduced; although the flux is improved by adding the inorganic nanoparticles in the interfacial polymerization process on the premise of keeping a good desalting rate, the problems of high preparation difficulty and easy shedding in the later period when the inorganic nanoparticles are used on a large scale limit the industrial application of the inorganic nanoparticles. Therefore, a simple and feasible technical scheme capable of improving the water flux of the reverse osmosis membrane on the premise of keeping the desalination rate to be reduced to a small degree is needed.

Disclosure of Invention

The invention aims to provide a high-flux reverse osmosis membrane, a preparation method and application thereof, so as to overcome the defects in the prior art.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides a large-flux reverse osmosis membrane, which comprises a porous support membrane and a polyamide layer formed on the support membrane, wherein the polyamide layer is doped with B-group water-soluble vitamins.

The large-flux reverse osmosis membrane provided by the invention is a porous support membrane in the prior art, and in a preferred embodiment, the porous support membrane is a polysulfone support membrane formed on non-woven fabrics. The polysulfone support membrane can be prepared by a method known in the art, and is not particularly limited. In a preferred embodiment, the polymer solution for preparing the polysulfone support membrane may contain 16.0-20.0 wt% of polysulfone resin, 10.0-15.0 wt% of ethylene glycol monomethyl ether, 0.01-1.0 wt% of sodium dodecyl sulfate, which are dissolved in a polar solvent to obtain a polysulfone membrane casting solution; then the polysulfone membrane casting solution after filtration and deaeration is coated on non-woven fabrics (such as polyester non-woven fabrics and the like); then the membrane is subjected to phase conversion in a gel bath to form a membrane, and the polysulfone support membrane is obtained after cleaning; the polar solvent preferably comprises one or more of N, N-dimethylformamide, N-dimethylacetamide or N-methylpyrrolidone.

The inventor surprisingly finds that when a specific B group water-soluble vitamin is added into a polyfunctional amine solution and then undergoes interfacial polycondensation with a polybasic acyl halide during the preparation of a polyamide layer, on one hand, the B group water-soluble vitamin can be used as a blocking agent to react with the acyl halide group of the polybasic acyl halide, so that the structure of the polyamide layer is regulated, the crosslinking degree of the polyamide layer is reduced, and more water production channels are provided; on the other hand, the hydrophilic group contained in the B-group water-soluble vitamin improves the hydrophilicity of the polyamide layer and reduces the water permeation resistance. Therefore, by adding a B-group water-soluble vitamin to the aqueous solution containing the polyfunctional amine, a large flux reverse osmosis membrane can be obtained.

The high-flux reverse osmosis membrane comprises B-group water-soluble vitamins including one or more of vitamin B1, vitamin B2, vitamin B6, vitamin B8 and vitamin B12, preferably, the vitamin B1 comprises thiamine pyrophosphate, the vitamin B2 comprises riboflavin and phosphate thereof, the vitamin B6 comprises pyridoxamine and salt thereof, the vitamin B8 comprises 5' -adenylic acid, and the vitamin B12 is cobalamin. The B-group water-soluble vitamin is preferably thiamine pyrophosphate, riboflavin sodium phosphate, pyridoxamine dihydrochloride, 5' -adenylic acid and vitamin B12. The mass percentage of the B-group water-soluble vitamin in the polyamine solution is preferably 0.001-3.0 wt%, and more preferably 0.01-1.0 wt%.

In a preferred embodiment of the large flux reverse osmosis membrane of the present invention, the polyamide layer is a crosslinked aromatic polyamide having a three-dimensional network structure formed by interfacial polycondensation of m-phenylenediamine and trimesoyl chloride.

The polyamide layer can be prepared by a method known in the art, and is not particularly limited. In a preferred embodiment, the method comprises the following steps:

contacting the porous support membrane with an aqueous phase solution containing B-group water-soluble vitamins and polyfunctional amine, removing the surface redundant aqueous phase solution, then contacting with an organic phase solution containing polybasic acyl halide (preferably uniformly coating), then carrying out heat treatment, and finally storing the obtained reverse osmosis membrane in deionized water.

In the specific implementation operation, the porous support membrane can be contacted with a single side or double sides of the aqueous phase solution, redundant aqueous phases on the surface can be removed by a squeeze roller or drained in air, and then the organic phase solution is uniformly coated on the surface of the porous support membrane; the obtained reverse osmosis membrane can be vertically drained to remove redundant organic phase, and finally is subjected to heat treatment, and the obtained reverse osmosis membrane is stored in deionized water.

Preferably, the amount of the polyfunctional amine in the aqueous solution is 1.0 to 10.0 wt%, more preferably 1.5 to 6.0 wt%. The content of the B group water-soluble vitamin may be 0.001 to 3.0 wt%, preferably 0.01 to 1.0 wt%. In the organic phase solution, the concentration of the polybasic acyl halide is preferably 0.01 to 10.0 wt%, and more preferably 0.05 to 3.0 wt%. The organic phase solution can also contain a complexing agent, and the complexing agent can be a trialkyl phosphate compound, preferably tributyl phosphate. The concentration of the complexing agent is preferably 0.01-1.0 wt%. The temperature of the organic phase solution is preferably in the range of 20 to 60 ℃, more preferably in the range of 25 to 50 ℃. The heat treatment temperature is preferably 40-130 ℃, more preferably 60-130 ℃, and the heat treatment time is preferably 1-15 minutes, more preferably 2-10 minutes, so that the organic phase solution on the surface of the reverse osmosis membrane is completely removed.

In a second aspect of the present invention, there is provided a method for producing a large-flux reverse osmosis membrane according to the present invention, wherein a B-group water-soluble vitamin is added to an aqueous polyfunctional amine solution, and the B-group water-soluble vitamin is allowed to participate in a reaction of forming polyamide by interfacial polycondensation of a polyfunctional amine and a polybasic acid halide, thereby forming a B-group water-soluble vitamin-doped polyamide layer on a porous support membrane. In a preferred embodiment, the method comprises in particular the steps of:

(1) preparation of aqueous phase solution: dissolving polyfunctional amine, triethylamine, camphorsulfonic acid and B-group water-soluble vitamins in water, and uniformly mixing to obtain a polyfunctional amine aqueous phase solution containing the B-group water-soluble vitamins;

(2) contacting the porous support membrane with a polyfunctional amine aqueous phase solution containing B-group water-soluble vitamins, removing the surface redundant aqueous phase, contacting with an organic phase solution containing polybasic acyl halide, performing heat treatment, and storing the obtained reverse osmosis membrane in deionized water.

In a preferred embodiment of the method for preparing a large-flux reverse osmosis membrane of the present invention, the polyfunctional amine in step (1) is an amine containing at least two primary amine groups, and includes aromatic amines including phenylenediamine, xylylenediamine, and 1,3, 5-triaminobenzene bonded to a benzene ring at ortho-, meta-, and para-positions, and aliphatic amines including ethylenediamine, propylenediamine, and piperazine; the polyfunctional amine is more preferably m-phenylenediamine; preferably, the mass percent of the polyfunctional amine in the aqueous phase solution is 1.0-10.0 wt%, and more preferably 1.5-6.0 wt%; the mass percentage of the B-group water-soluble vitamin is preferably 0.001 to 3.0 wt%, more preferably 0.01 to 1.0 wt%.

The aqueous polyfunctional amine solution may also contain an acid acceptor, provided that a polyamide layer is formed. The acid acceptor comprises weak base, a buffer pair consisting of the weak base and acid, or alkali metal hydroxide, carbonate and bicarbonate, and organic compounds; the weak base comprises triethylamine and sodium phosphate; the buffer pair comprises triethylamine hydrochloride and triethylamine camphorsulfonate; the hydroxide, carbonate and bicarbonate of alkali metal include sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate and potassium bicarbonate, and the organic compound includes tetramethylammonium hydroxide and tetraethylammonium hydroxide. The acid acceptor is preferably triethylamine camphorsulfonate; preferably, the aqueous phase solution contains 1.1-3.5 wt% of triethylamine and 2.3-6.5 wt% of camphorsulfonic acid, and the pH value of the aqueous phase after the triethylamine camphorsulfonate is preferably 9-12.

In the method for preparing a large-flux reverse osmosis membrane of the present invention, in the step (2), the porous support membrane may be contacted with the aqueous polyfunctional amine solution on one side or both sides, and specifically, for example, the aqueous polyfunctional amine solution may be coated on the surface of the porous support membrane or the porous support membrane may be immersed in the aqueous polyfunctional amine solution. The contact time of the porous support membrane and the polyfunctional amine aqueous solution is preferably within the range of 0.1-10 minutes, and more preferably within the range of 0.5-3 minutes; the contact temperature is preferably 10 to 50 ℃, more preferably 15 to 35 ℃. The excessive water phase on the surface can be removed in various ways, such as keeping the porous support membrane vertical so that the excessive water phase naturally flows down; or extrusion removal by adopting an extrusion roller or forced removal by adopting air knife to spray gas and the like. After that, the organic phase solution containing the polybasic acid halide is preferably uniformly applied to the surface of the porous support membrane of the aqueous polyfunctional amine solution.

In the organic phase solution, the polybasic acyl halide comprises aromatic and/or aliphatic polybasic acyl halide, the aromatic polybasic acyl halide comprises trimesoyl chloride, terephthaloyl chloride and naphthaline dicarboxylic acid chloride, the aliphatic polybasic acyl halide comprises adipoyl chloride, cyclopropane tricarboxyyl chloride and tetrahydrofuran diformyl chloride, and the polybasic acyl halide is more preferably trimesoyl chloride; preferably, the concentration of the polybasic acyl halide in the organic phase solution is 0.01-10.0 wt%, and more preferably 0.05-3.0 wt%. The solvent of the organic phase solution is not particularly limited as long as it is not miscible with water, and examples thereof include straight-chain alkanes such as n-hexane, n-heptane, n-decane and n-dodecane, and isoparaffins such as isopar G, isopar L and isopar E from Mobil corporation. The organic phase solution can also contain a complexing agent, and the complexing agent can use a trialkyl phosphate compound, preferably tributyl phosphate; the concentration of the complexing agent is preferably 0.01-1.0 wt%.

The temperature of the organic phase solution is preferably in the range of 20 to 60 ℃, more preferably in the range of 25 to 50 ℃.

The flux and interception performance of the polyamide composite membrane prepared by the method are improved through further heat treatment, the heat treatment temperature is preferably 40-130 ℃, more preferably 60-110 ℃, the heat treatment time is preferably 1-15 minutes, more preferably 2-10 minutes, and therefore organic phase solution on the surface of the reverse osmosis membrane is completely removed.

In a third aspect, the present invention provides a use of a large flux reverse osmosis membrane as described above or a reverse osmosis membrane produced by the above-described production method in a water treatment module or apparatus, or in a water treatment method. The "water treatment module or apparatus" may be any module or apparatus to which the polyamide reverse osmosis membrane of the present invention is attached, which can be applied to a water treatment process. The expression "used in a water treatment module or apparatus" includes application to a module or apparatus product on which the polyamide reverse osmosis membrane of the present invention is mounted, and also includes application to the production of such a module or apparatus product. The modules may be, for example, spiral wound membrane modules, disc and tube flat membrane modules, and the like. The device can be, for example, a household/commercial reverse osmosis water purifier, an industrial boiler feed water reverse osmosis pure water device, an industrial reclaimed water reuse reverse osmosis device, a seawater desalination device and the like. The water treatment method may be, for example: drinking water production, wastewater reuse, seawater desalination, beverage concentration and the like.

The technical scheme provided by the invention has the following beneficial effects:

the B-group water-soluble vitamins are added in the preparation process of the reverse osmosis membrane, and the hydrophilic groups contained in the B-group water-soluble vitamins improve the hydrophilicity of the membrane surface, so that the formation of a water layer on the surface of the membrane and the subsequent dissolution and diffusion of water in the membrane are facilitated. The hydrophilic groups are easy to ionize in water, and the rejection effect on salt in water is stronger than that of a blank sample, so that the water flux can be improved and the higher desalination rate can be maintained under a certain B vitamin concentration. The polyamide reverse osmosis membrane provided by the invention has the characteristics of large flux and high salt removal rate, in an optimized specific embodiment, a feed liquid is 2000ppm of sodium chloride aqueous solution, the pH value of the solution is 7.5 +/-0.5, the operating pressure is 225psi, the operating temperature is 25 ℃, and the flux can reach 70L/(m & lt/m & gt) ²H) in which case NaCl removals higher than 99.3% are still obtained. Meanwhile, the preparation method is simple to operate, easy for industrial production and applicable to the water treatment fields of industrial water supply, wastewater reuse and the like.

Detailed Description

In order to better understand the technical solution of the present invention, the following examples are further provided to illustrate the present invention, but the present invention is not limited to the following examples.

The raw materials used in the following examples or comparative examples, unless otherwise specified, are all commercially available conventional raw materials, and the information on the main raw materials is shown in table 1 below.

Table 1: information on main raw materials

The following is a description of the processes used or possible to be used in the examples or comparative examples of the present invention:

1. evaluation of salt rejection and permeation flux

Salt rejection and permeate flux are two important parameters for evaluating the separation performance of reverse osmosis membranes. According to GB/T32373-2015 reverse osmosis membrane test method, the separation performance of the reverse osmosis membrane is evaluated.

The salt rejection (R) is defined as: under certain operating conditions, the salt concentration (C) of the feed liquid _f) With the salt concentration (C) in the permeate _p) The difference is divided by the salt concentration (C) of the feed solution _f) As shown in formula (1).

Permeate flux is defined as: the volume of water per membrane area per unit time that permeates under certain operating conditions is expressed in L/(m) ²·h)。

The reverse osmosis membrane performance measurement adopts the following operating conditions: the feed solution was 2000ppm aqueous sodium chloride, the pH of the solution was 7.5. + -. 0.5, the operating pressure was 225psi and the operating temperature was 25 ℃.

Comparative example 1

The preparation process of the high-flux reverse osmosis membrane is as follows:

the method comprises the following steps: the preparation of the polysulfone support membrane specifically comprises the following steps: 500g of polysulfone membrane casting solution containing 16.5 wt% of polysulfone resin, 10.0 wt% of ethylene glycol monomethyl ether and 0.1 wt% of sodium dodecyl sulfate is prepared in N, N-dimethylformamide; then the polysulfone membrane casting solution after filtering and defoaming is coated and scraped on a polyester non-woven fabric; immediately soaking in coagulating bath deionized water, performing phase conversion to obtain a membrane, cleaning to obtain a polysulfone support membrane, and cutting the membrane into 16cm × 12cm membranes;

step two: weighing 27g of m-phenylenediamine, 32g of camphorsulfonic acid and 15g of triethylamine, dissolving the m-phenylenediamine, the camphorsulfonic acid and the triethylamine in 926g of deionized water, stirring and mixing the mixture evenly to prepare an aqueous solution, and keeping the temperature of the aqueous solution at 25 +/-1 ℃;

step three: weighing 1.6g of trimesoyl chloride and 1.76g of tributyl phosphate, dissolving in 996.64g of isopar G isoalkane, stirring and mixing uniformly to prepare an organic phase solution, and keeping the temperature of the organic phase solution at 50 +/-1 ℃;

step four: adhering the polysulfone base membrane prepared in the step one to a plate frame, immersing the plate frame in the water phase solution prepared in the step two for 30s, taking out the plate frame, placing the plate frame on a paper towel on the top of a plastic plate, slightly extruding by using a press roller to remove the residual water phase solution on the surface, then contacting the organic phase solution containing trimesoyl chloride in the step three for reaction for 20s, and carrying out interfacial polycondensation to form a polyamide composite membrane; vertically draining the membrane for 1min to remove redundant oil phase solution on the surface, and then putting the composite membrane into a 100 ℃ oven for heat treatment for 6 min; and finally, soaking the obtained cross-linked aromatic polyamide reverse osmosis membrane in deionized water to be tested.