阅读说明：本技术 一种高通量聚乙烯基反渗透膜及其制备方法和应用 (High-flux polyethylene-based reverse osmosis membrane and preparation method and application thereof ) 是由 苏蕾 邬军辉 赵伟国 孙家宽 于 2021-07-28 设计创作，主要内容包括：本发明公开了一种高通量聚乙烯基反渗透膜及其制备方法和应用,所述反渗透膜包括亲水化聚乙烯多孔支撑层,中间层和形成于中间层上的聚酰胺脱盐层；所述中间层通过在亲水化聚乙烯多孔支撑层上涂布含氨基和磺酸基的苯系化合物、聚-2-乙基-2-噁唑啉和聚乙二醇二缩水甘油醚的混合溶液后加热反应制备而成。通过本发明制备得到的聚乙烯基反渗透膜具有明显更高的通量和脱盐率。(The invention discloses a high-flux polyethylene-based reverse osmosis membrane and a preparation method and application thereof, wherein the reverse osmosis membrane comprises a hydrophilized polyethylene porous supporting layer, a middle layer and a polyamide desalting layer formed on the middle layer; the middle layer is prepared by coating a mixed solution of a benzene compound containing amino and sulfonic acid groups, poly-2-ethyl-2-oxazoline and polyethylene glycol diglycidyl ether on a hydrophilic polyethylene porous support layer and then heating for reaction. The polyethylene-based reverse osmosis membrane prepared by the method has obviously higher flux and salt rejection rate.)

1. A high flux polyethylene-based reverse osmosis membrane comprising a hydrophilized polyethylene porous support layer, an intermediate layer and a polyamide desalination layer formed on the intermediate layer;

the middle layer is prepared by coating a mixed solution of a benzene compound containing amino and sulfonic acid groups, poly-2-ethyl-2-oxazoline and polyethylene glycol diglycidyl ether on a hydrophilic polyethylene porous support layer and then heating for reaction.

2. The high-throughput polyvinyl reverse osmosis membrane according to claim 1, wherein the benzene-based compound containing an amino group and a sulfonic acid group is a compound having 1 or more active amino groups, 1 or more sulfonic acid groups, and 1 or more benzene ring groups, preferably one or more of sodium aminobenzenesulfonate, sodium metaaminobenzenesulfonate, sodium 2-aminobenzenesulfonate, 3-aminobenzenesulfonic acid, sulfanilic acid, 2-aminobenzenesulfonic acid, sodium 2, 4-diaminobenzenesulfonate, sodium 3, 4-diaminobenzenesulfonate, 2, 4-diaminobenzenesulfonic acid, 3, 4-diaminobenzenesulfonic acid, 4, 4-diaminodiphenylamine-2-sulfonic acid, and more preferably sodium aminobenzenesulfonate.

3. The high throughput polyethylene-based reverse osmosis membrane of claim 1, wherein the polyamide desalination layer is obtained by interfacial polymerization of an aqueous phase comprising an active amino compound having 2 or more amino groups and an organic phase comprising a polyfunctional acid halide.

4. The high flux polyethylene-based reverse osmosis membrane according to any one of claims 1 to 3, wherein the compound having 2 or more active amino groups is a polyfunctional amine of aromatic, aliphatic, or alicyclic type, preferably one or more of m-phenylenediamine, o-phenylenediamine, 1,3, 5-triaminobenzene, 1,2, 4-triaminobenzene, 3, 5-diaminobenzoic acid, 2, 4-diaminotoluene, 2, 6-diaminotoluene, 2, 4-diaminoanisoyl, amol, xylylenediamine, ethylenediamine, propylenediamine, tris (2-aminoethyl) amine, 1, 3-diaminocyclohexane, 1, 2-diaminocyclohexane, 1, 4-diaminocyclohexane, piperazine, 2, 5-dimethylpiperazine, and 4-aminomethylpiperazine, more preferably m-phenylenediamine;

the polyfunctional acid halide is one or more of aromatic, aliphatic or alicyclic polyfunctional acid halides, preferably trimesoyl chloride, terephthaloyl chloride, isophthaloyl chloride, biphenyldicarboxylic acid chloride, naphthalenedicarboxylic acid dichloride, benzenetrisulfonyl chloride, benzenedisulfonyl chloride, monochlorosulfonylbenzenedicarboxylic acid chloride, propanetricarboxylic acid chloride, butanetricarboxylic acid chloride, pentanetricarboxylic acid chloride, glutaryl halide, adipyl halide, cyclopropanetricarboxylic acid chloride, cyclobutanetetracarboxylic acid chloride, cyclopentanetricarboxylic acid chloride, cyclopentanetetracarboxylic acid chloride, cyclohexanetricarboxylic acid chloride, tetrahydrofurfuryl tetracarboxylic acid chloride, cyclopentanedicarboxylic acid chloride, cyclobutanedicarboxyl chloride, cyclohexanedicarboxylic acid chloride, tetrahydrofurfuryl dicarboxylic acid chloride, more preferably trimesoyl chloride.

5. A method of preparing a high flux polyethylene-based reverse osmosis membrane according to any one of claims 1-4, comprising the steps of:

1) coating a mixed solution of a benzene compound containing amino and sulfonic acid groups, poly-2-ethyl-2-oxazoline and polyethylene glycol diglycidyl ether on a hydrophilized polyethylene porous support layer, and heating to react to prepare an intermediate layer;

2) soaking the hydrophilic polyethylene porous support membrane with the middle layer in a soaking solution, and then putting the hydrophilic polyethylene porous support membrane into pure water for washing;

3) soaking the soaked porous support membrane in a water phase containing more than 2 active amino compounds for 15-30s, removing the redundant water phase on the surface, contacting with an organic phase containing polyfunctional acyl halide, carrying out interfacial polymerization reaction, removing excessive liquid, and drying to obtain the reverse osmosis membrane.

6. The method for preparing a high flux polyethylene-based reverse osmosis membrane according to claim 5, wherein the mixed solution coated on the hydrophilized polyethylene porous support layer of step 1) comprises the following components: 0.01-0.05 wt% of benzene series compound containing amino and sulfonic group, 0.01-0.05 wt% of poly-2-ethyl-2-oxazoline and 0.01-0.1 wt% of polyethylene glycol diglycidyl ether.

7. The method of claim 6, wherein the heating in step 1) is performed at 50-80 ℃ for 1-5 min.

8. The method of claim 5, wherein the wetting solution in step 2) is at least one of isopropanol, ethanol and methanol, preferably ethanol.

9. The method of claim 5, wherein the mass concentration of the active amino compound in the aqueous phase of step 3) is 2.0 to 6.0 wt%, and the mass concentration of the polyfunctional acid halide in the organic phase is 0.05 to 0.2 wt%;

preferably, the contact time of the organic phase and the water phase interface polymerization in the porous support membrane is 10-30 s.

10. Use of the high flux polyethylene-based reverse osmosis membrane according to any one of claims 1-4 in a water treatment component or device or in a water treatment process.

Technical Field

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

Background

The reverse osmosis membrane has been widely used in the fields of household water purifiers, industrial pure water production, wastewater treatment, seawater desalination and the like because of its characteristics of high separation efficiency, low energy consumption, little pollution and the like. Currently, the mainstream reverse osmosis membrane in the market is a crosslinked aromatic polyamide composite reverse osmosis membrane, which comprises a three-layer structure, namely a PET non-woven fabric support layer, a polysulfone porous layer and a polyamide desalting layer. Wherein, the raw material cost of the PET non-woven fabrics and the polysulfone accounts for more than 2/3 of the cost of the reverse osmosis membrane, and the core production technology is monopolized by a few chemical companies for a long time, so the raw material cost for producing the reverse osmosis membrane is difficult to reduce.

In recent years, research on polyethylene microporous membranes serving as substrates is carried out, and the polyethylene composite reverse osmosis membrane with low cost and certain permeability is prepared. The related patents mostly focus on the poor hydrophilicity of the surface of the traditional polyethylene film and carry out hydrophilization modification, so as to solve the problem that the water phase is difficult to uniformly disperse on the surface in the interfacial polymerization process, and all make remarkable progress. The prior patents are mainly disclosed by pure water replacement after wetting by organic solvent (for example, Chinese published patent CN 112246104A), hydrophilic material impregnation modification (for example, Chinese published patent CN111760464A), low-pressure plasma and PVA cross-linking coating modification (for example, Chinese published patent CN 109126483A). In the pure water replacement aspect after wetting with the organic solvent, chinese patent publication CN112246104A discloses wetting a polyethylene material with an organic solvent with low surface tension such as alcohols or phenols in advance, and then removing the solvent for use, thereby successfully preparing a reverse osmosis membrane. In the aspect of hydrophilic material impregnation modification, the Chinese patent publication CN111760464A discloses that after a polyethylene film is placed in a polymer solution with hydroxyl groups for hydrophilic modification, the polyethylene film is further treated to prepare a reverse osmosis membrane, and the separation performance is remarkably improved. In the aspects of low-pressure plasma and PVA cross-linking coating modification, the method for preparing the reverse osmosis membrane by treating the polyethylene membrane by using the low-pressure plasma and then coating the cross-linked PVA in the China published patent CN109126483A has higher industrial feasibility and promotes the large-scale application of the polyethylene membrane in the field of reverse osmosis base membranes.

Although some technical solutions for preparing reverse osmosis membranes using polyethylene membranes have been developed in the prior art, there is room for improvement in terms of both industrial feasibility and flux improvement.

Disclosure of Invention

The invention aims to provide a high-flux polyethylene-based reverse osmosis membrane which has the characteristics of industrial feasibility, high flux and high desalination rate.

The invention also aims to provide the preparation method of the high-flux polyethylene-based reverse osmosis membrane, which has the characteristics of simple operation, easy industrial production and the like.

It is a further object of the present invention to provide the use of the high flux polyethylene-based reverse osmosis membrane in a water treatment module or device, and/or in a water treatment process.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

the first aspect of the invention provides a high-flux polyethylene-based reverse osmosis membrane, which comprises a hydrophilized polyethylene porous support layer, an intermediate layer and a polyamide desalting layer formed on the intermediate layer;

the middle layer is prepared by coating a mixed solution of a benzene compound containing amino and sulfonic acid groups, poly-2-ethyl-2-oxazoline and polyethylene glycol diglycidyl ether on a hydrophilic polyethylene porous support layer and then heating for reaction.

The benzene compound containing an amino group and a sulfonic acid group is a compound having 1 or more active amino groups, 1 or more sulfonic acid groups, and 1 or more benzene ring groups, and is preferably one or more of sodium aminobenzenesulfonate, sodium metaaminobenzenesulfonate, sodium 2-aminobenzenesulfonate, 3-aminobenzenesulfonic acid, sulfanilic acid, 2-aminobenzenesulfonic acid, sodium 2, 4-diaminobenzenesulfonate, sodium 3, 4-diaminobenzenesulfonate, 2, 4-diaminobenzenesulfonic acid, 3, 4-diaminobenzenesulfonic acid, 4, 4-diaminodiphenylamine-2-sulfonic acid, and more preferably sodium aminobenzenesulfonate.

In the present invention, the polyamide desalting layer is obtained by interfacial polymerization of an aqueous phase containing a compound having 2 or more reactive amino groups and an organic phase containing a polyfunctional acid halide.

The compound having 2 or more reactive amino groups may be any polyfunctional amine, and aromatic, aliphatic or alicyclic polyfunctional amines may be used, and the polyfunctional amines may be used alone or as a mixture.

Examples of the aromatic polyfunctional amines include m-phenylenediamine, o-phenylenediamine, 1,3, 5-triaminobenzene, 1,2, 4-triaminobenzene, 3, 5-diaminobenzoic acid, 2, 4-diaminotoluene, 2, 6-diaminotoluene, 2, 4-diaminoanisoyl, amoebol, and xylylenediamine;

examples of the aliphatic polyfunctional amine include ethylenediamine, propylenediamine, tris (2-aminoethyl) amine;

examples of the alicyclic polyfunctional amine include 1, 3-diaminocyclohexane, 1, 2-diaminocyclohexane, 1, 4-diaminocyclohexane, piperazine, 2, 5-dimethylpiperazine and 4-aminomethylpiperazine;

among the above polyfunctional amines, m-phenylenediamine is more preferable.

The polyfunctional acid halide may be an aromatic, aliphatic or alicyclic polyfunctional acid halide, and the polyfunctional acid halide may be used alone or as a mixture.

Examples of the aromatic polyfunctional acid halide include preferably trimesoyl chloride, terephthaloyl chloride, isophthaloyl chloride, biphenyldicarboxylic acid chloride, naphthalenedicarboxylic acid dichloride, benzenetrisulfonyl chloride, benzenedisulfonyl chloride, monochlorosulfonylbenzenedicarboxylic acid dichloride;

examples of the aliphatic polyfunctional acid halide include propane tricarboxylic acid chloride, butane tricarboxylic acid chloride, pentane tricarboxylic acid chloride, glutaryl halide, adipoyl halide;

examples of the alicyclic polyfunctional acid halide include cyclopropane tricarboxylic acid chloride, cyclobutane tetracarboxylic acid chloride, cyclopentane tricarboxylic acid chloride, cyclopentane tetracarboxylic acid chloride, cyclohexane tetracarboxylic acid chloride, tetrahydrofuran tetracarboxylic acid chloride, cyclopentane dicarboxylic acid chloride, cyclobutane dicarboxylic acid chloride, cyclohexane dicarboxylic acid chloride, tetrahydrofuran dicarboxylic acid chloride, and tetrahydrofuran dicarboxylic acid chloride;

among the above polyfunctional acid halides, trimesoyl chloride is more preferred.

In the invention, the hydrophilized polyethylene porous support layer is a hydrophilized porous support film obtained by treating a polyethylene film with low-pressure plasma, and the pore diameter is 20-40 nm.

The inventor of the application unexpectedly finds that the membrane surface crack defect is easy to generate by treating the polyethylene base membrane by using low-pressure plasma to hydrophilize the polyethylene base membrane, and high desalination rate is difficult to obtain if the polyethylene base membrane is directly applied to preparation of a reverse osmosis membrane. Further, when a reverse osmosis membrane is prepared by coating crosslinked PVA on a treated polyethylene-based membrane having a crack defect, it is difficult to obtain a high flux although the salt rejection is improved. And after a mixed solution of sodium aminobenzenesulfonate, poly-2-ethyl-2-oxazoline and polyethylene glycol diglycidyl ether is coated on the hydrophilic polyethylene porous supporting layer and is heated to react to generate an intermediate layer, the reverse osmosis membrane is prepared, so that the flux and the salt rejection rate are obviously improved. Because poly-2-ethyl-2-oxazoline and polyethylene glycol diglycidyl ether which have linear structures and certain molecular weights generate cross-linking reaction in the heating process, the film surface crack defect can be effectively covered by lower coating amount; for the addition of the sodium aminobenzenesulfonate, on one hand, the sodium aminobenzenesulfonate participates in a crosslinking reaction, and a carried benzene ring structure can effectively enlarge the molecular chain gap of the middle layer and endow the middle layer with higher water flux; on the other hand, the carried sulfonate can endow the interlayer with excellent hydrophilic performance, so that the water molecule passing resistance of the interlayer is further reduced. Therefore, when the intermediate layer is heated by coating the mixed solution of sodium aminobenzenesulfonate, poly-2-ethyl-2-oxazoline and polyethylene glycol diglycidyl ether on the surface of the hydrophilized polyethylene film and then the hydrophilized polyethylene film is used for preparing the reverse osmosis membrane, the salt rejection rate of the reverse osmosis membrane can be improved, and meanwhile, the membrane is endowed with excellent water flux.

In a preferred embodiment of the high flux polyethylene-based reverse osmosis membrane of the present invention, the porous support layer is a hydrophilized polyethylene film. The hydrophilized polyethylene film can be produced by a technique known in the art, and is not particularly limited. In general, a polyethylene film is often treated by a low-pressure plasma treatment technique to obtain a hydrophilized polyethylene film, and for example, it can be produced by the method disclosed in chinese patent publication CN 109126483A.

The second aspect of the invention provides a preparation method of the high-flux polyethylene-based reverse osmosis membrane, which comprises the following steps:

1) coating a mixed solution of a benzene compound containing amino and sulfonic acid groups, poly-2-ethyl-2-oxazoline and polyethylene glycol diglycidyl ether on a hydrophilized polyethylene porous support layer, and heating to react to prepare an intermediate layer;

2) soaking the hydrophilic polyethylene porous support membrane with the middle layer in a soaking solution, and then putting the hydrophilic polyethylene porous support membrane into pure water for washing;

3) soaking the soaked porous support membrane in a water phase containing more than 2 active amino compounds for 15-30s, removing the redundant water phase on the surface, contacting with an organic phase containing polyfunctional acyl halide, carrying out interfacial polymerization reaction, removing excessive liquid, and drying to obtain the reverse osmosis membrane.

The benzene-series compound containing an amino group and a sulfonic acid group, the compound having 2 or more reactive amino groups, and the polyfunctional acid halide in the preparation method have the same definitions as above, that is:

the benzene compound containing amino and sulfonic acid groups is a compound having 1 or more active amino groups, 1 or more sulfonic acid groups and 1 or more benzene ring groups, preferably one or more of sodium aminobenzenesulfonate, sodium metaaminobenzenesulfonate, sodium 2-aminobenzenesulfonate, 3-aminobenzenesulfonic acid, sulfanilic acid, 2-aminobenzenesulfonic acid, sodium 2, 4-diaminobenzenesulfonate, sodium 3, 4-diaminobenzenesulfonate, 2, 4-diaminobenzenesulfonic acid, 3, 4-diaminobenzenesulfonic acid, 4, 4-diaminodiphenylamine-2-sulfonic acid, and more preferably sodium aminobenzenesulfonate;

the compound having 2 or more active amino groups is one or more aromatic, aliphatic, or alicyclic polyfunctional amines, preferably m-phenylenediamine, o-phenylenediamine, 1,3, 5-triaminobenzene, 1,2, 4-triaminobenzene, 3, 5-diaminobenzoic acid, 2, 4-diaminotoluene, 2, 6-diaminotoluene, 2, 4-diaminoanisoyl, amonol, xylylenediamine, ethylenediamine, propylenediamine, tris (2-aminoethyl) amine, 1, 3-diaminocyclohexane, 1, 2-diaminocyclohexane, 1, 4-diaminocyclohexane, piperazine, 2, 5-dimethylpiperazine, and 4-aminomethylpiperazine, more preferably m-phenylenediamine;

the polyfunctional acid halide is one or more of aromatic, aliphatic or alicyclic polyfunctional acid halides, preferably trimesoyl chloride, terephthaloyl chloride, isophthaloyl chloride, biphenyldicarboxylic acid chloride, naphthalenedicarboxylic acid dichloride, benzenetrisulfonyl chloride, benzenedisulfonyl chloride, monochlorosulfonylbenzenedicarboxylic acid chloride, propanetricarboxylic acid chloride, butanetricarboxylic acid chloride, pentanetricarboxylic acid chloride, glutaryl halide, adipyl halide, cyclopropanetricarboxylic acid chloride, cyclobutanetetracarboxylic acid chloride, cyclopentanetricarboxylic acid chloride, cyclopentanetetracarboxylic acid chloride, cyclohexanetricarboxylic acid chloride, tetrahydrofurfuryl tetracarboxylic acid chloride, cyclopentanedicarboxylic acid chloride, cyclobutanedicarboxyl chloride, cyclohexanedicarboxylic acid chloride, tetrahydrofurfuryl dicarboxylic acid chloride, more preferably trimesoyl chloride.

In a preferred embodiment, in the mixed solution coated on the hydrophilized polyethylene porous support layer in step 1), the contents of the components are as follows: 0.01-0.05 wt% of benzene series compound containing amino and sulfonic group, 0.01-0.05 wt% of poly-2-ethyl-2-oxazoline and 0.01-0.1 wt% of polyethylene glycol diglycidyl ether.

The reaction of the mixed solution of the benzene compound containing amino and sulfonic group, the poly-2-ethyl-2-oxazoline and the polyethylene glycol diglycidyl ether in the step 1) under the heating condition comprises the reaction of the amino in the benzene compound containing amino and sulfonic group and the epoxy group of the polyethylene glycol diglycidyl ether, and also comprises the reaction of the amino formed by the poly-2-ethyl-2-oxazoline under the heating condition and the epoxy group of the polyethylene glycol diglycidyl ether. Specifically, the heating reaction condition in the step 1) is that the reaction is carried out for 1-5min at 50-80 ℃.

In a preferred embodiment, the impregnating solution in the step 2) is at least one of isopropanol, ethanol and methanol, preferably ethanol; soaking for about 1 min.

In a preferred embodiment, the mass concentration of the active amino compound in the aqueous phase in step 3) is from 2.0 to 6.0% by weight, and the mass concentration of the polyfunctional acid halide in the organic phase is from 0.05 to 0.2% by weight;

preferably, the contact time of the organic phase and the water phase interface polymerization in the porous support membrane is 10-30 s.

A third aspect of the present invention is to provide the use of a high flux polyethylene-based reverse osmosis membrane as hereinbefore described in the preparation of a water treatment component or apparatus, and/or in a water treatment process. The water treatment module or apparatus may be any module or apparatus to which the high flux polyethylene-based reverse osmosis membrane of the present invention is installed, which can be applied to a water treatment process. The term "in a water treatment module or unit" includes application to a module or unit product incorporating the high flux polyethylene-based reverse osmosis membrane of the present invention, and also includes application to the production of such a module or unit product. The modules may be, for example, spiral wound membrane modules, disc and tube flat membrane modules, and the like. The device can be used for example as a household/commercial reverse osmosis water purifier, an industrial feed water reverse osmosis water purifier, and the like. The water treatment method may be, for example: drinking water production, industrial water supply and the like.

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

(1) the reverse osmosis membrane provided by the invention has the characteristics of high flux and high salt rejection rate, and the permeation flux can reach 50L/(m) under the test conditions of treating 500ppm sodium chloride and 0.69MPa which are known in the industry²H) above, the desalination rate of sodium chloride can reach 99.4% or above. Therefore, the method can be applied to the water treatment fields of household water purification, industrial water supply and the like.

(2) Compared with the traditional reverse osmosis membrane preparation method adopting PET non-woven fabrics and polysulfone base membranes, the preparation method of the high-flux polyethylene-based reverse osmosis membrane provided by the invention has lower manufacturing cost. The preparation method of the invention is also characterized by easy industrial production and the like.

Detailed Description

The present invention is further illustrated by the following specific examples, which are intended to be illustrative of the invention and are not to be construed as limiting the scope of the invention.

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

TABLE 1 information on the main raw materials

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

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. The invention evaluates the separation performance of the reverse osmosis membrane according to GB/T32373 and 2015 reverse osmosis membrane test method.

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 a500 ppm aqueous sodium chloride solution, the pH of the solution was 7.0. + -. 0.5, the operating pressure was 0.69MPa, and the operating temperature was 25 ℃.

Examples 1 to 3

A polyethylene-based reverse osmosis membrane was prepared according to the following procedure, except that the raw material concentrations and reaction parameters in the examples were different in table 1:

(1) hydrophilization treatment of polyethylene film: the low-pressure oxygen plasma treatment power is 50W, the treatment pressure is 25Pa, the treatment time is 180s, and the polyethylene film is subjected to low-pressure plasma treatment. The treated membrane was then stored stably for 3 days to obtain a hydrophilized polyethylene porous support membrane.

(2) Preparing an intermediate layer: preparing 500g of mixed solution C of sodium aminobenzenesulfonate and poly-2-ethyl-2-oxazoline and 500g of solution D of polyethylene glycol diglycidyl ether, and then mixing C, D solution at room temperature to obtain mixed solution E. And uniformly coating the solution E on the surface of the hydrophilic polyethylene film, then heating in an oven, and drying at 60 ℃ for 3min to obtain the intermediate layer.

(3) And (3) infiltration treatment: and (3) soaking the hydrophilized polyethylene porous support film with the intermediate layer in ethanol soaking liquid at normal temperature for 1min, and then placing the hydrophilized polyethylene porous support film in pure water to wash out the soaking liquid in the film, so as to obtain the polyethylene film with the intermediate layer after soaking treatment, namely the support film.

(4) Preparation of an aromatic polyamide desalting layer: firstly, preparing a water phase A500g containing m-phenylenediamine; then immersing the wet support membrane into the solution A to remove the redundant water on the surface; then the composite membrane is contacted with 25g of organic phase B containing trimesoyl chloride for reaction, and interfacial polycondensation is carried out to form a polyamide composite membrane; and finally, soaking the obtained cross-linked aromatic polyamide reverse osmosis membrane in deionized water to be detected.

The concentrations of the substances, the process conditions, and the evaluation results of the salt rejection and the permeation flux of the reverse osmosis membrane are shown in Table 1.

Comparative examples 1 to 3

A polyethylene-based reverse osmosis membrane was prepared according to the method of the example, but differs from the example in that: the preparation and treatment of the intermediate layer were not performed, and the raw material concentrations and reaction parameters in each comparative example were different as shown in table 1.

Comparative examples 4 to 7

A polyethylene-based reverse osmosis membrane was prepared according to the method of the example, but differs from the example in that: the intermediate layer was prepared with incomplete starting materials, and the starting material concentrations and reaction parameters for each ratio are specifically shown in table 1.

The concentrations of the respective substances, process conditions, and evaluation results of the salt rejection and permeation flux of the reverse osmosis membrane in the comparative example are shown in table 1.

Table 1, examples 1 to 3 and comparative examples 1 to 7 show production conditions and product evaluation results

Examples 4 to 8

A polyethylene-based reverse osmosis membrane was prepared according to the method of example 3, except that the types and amounts of the raw materials were selected and used as follows in Table 2. The evaluation results of salt rejection and permeation flux performance of the reverse osmosis membrane are recorded in table 2.

Table 2, preparation conditions and product evaluation results in examples 4 to 8

By combining the experimental results in tables 1 and 2, the intermediate layer of the invention is modified on the polyethylene base membrane, and the prepared reverse osmosis membrane has obviously higher flux and salt rejection rate.

The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, several modifications and additions can be made without departing from the method of the present invention, and these modifications and additions should also be regarded as the protection scope of the present invention.