A high-flux polyethylene-based reverse osmosis membrane and its preparation method and application

Abstract

The present 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 support layer and a polyamide desalination layer, and a polyhydroxy polymer intermediate layer of multimolecular channels is contained between the hydrophilized polyethylene porous support layer and the polyamide desalination layer. Wherein, the multi-molecular channel multi-hydroxy polymer intermediate layer is formed by cross-linking reaction of cyclodextrin and dialdehyde compound under the action of an acid catalyst. The multi-molecular channel multi-hydroxy polymer intermediate layer introduced by the present invention can not only increase the bonding force between the reverse osmosis polyamide desalination layer and the polysulfone support layer, making it more resistant to the back pressure generated by shutdown, but also has high water permeability and high salt removal performance at a low operating pressure of 0.4-0.9MPa, and is particularly suitable for long-term stable desalination treatment of tap water, light salt water, etc.

Description

Technical Field

[0001] 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 Art

[0002] Reverse osmosis membranes have been widely used in household water purifiers, industrial pure water manufacturing, wastewater treatment, and seawater desalination due to their high separation efficiency, low energy consumption, and low pollution. At present, the mainstream reverse osmosis membrane on the market is a cross-linked aromatic polyamide composite reverse osmosis membrane, which contains a three-layer structure, namely a PET non-woven fabric support layer, a polysulfone porous layer, and a polyamide desalination layer. Among them, the cost of PET non-woven fabrics and polysulfone raw materials accounts for more than 2 / 3 of the cost of reverse osmosis membranes, and its core production technology has long been monopolized by a few chemical companies. Therefore, the cost of raw materials for the production of reverse osmosis membranes is difficult to reduce.

[0003] In recent years, there have been studies based on polyethylene microporous membranes, and low-cost polyethylene composite reverse osmosis membranes with certain permeability have been prepared. Related patents are mostly concentrated on the poor hydrophilicity of the surface of traditional polyethylene membranes, and hydrophilic modification is carried out to solve the problem that the water phase in the interfacial polymerization process is difficult to be evenly dispersed on its surface, and more significant progress has been made. At present, the patents disclosed are mainly replaced by pure water after wetting with organic solvents (such as China Public Patent CN 112246104A), impregnated hydrophilic material modification (such as China Public Patent CN111760464A), low-pressure plasma and PVA cross-linked coating modification (such as China Public Patent CN109126483A). In terms of pure water replacement after wetting with organic solvents, China Public Patent CN112246104A uses low surface tension organic solvents such as alcohols or phenols to pre-wet the polyethylene material, and then removes the solvent for use, and successfully prepares a reverse osmosis membrane. In terms of modification by impregnation with hydrophilic materials, China's public patent CN111760464A places polyethylene membrane in a polyether or polyvinyl alcohol polymer solution for hydrophilic modification, and then further treats it to prepare a reverse osmosis membrane, achieving significantly improved separation performance. In terms of low-pressure plasma and PVA cross-linking coating modification, China's public patent CN109126483A uses a method of preparing a reverse osmosis membrane by treating a polyethylene membrane with low-pressure plasma and then coating it with cross-linked PVA, which is more industrially feasible and promotes the large-scale application of polyethylene membranes in the field of reverse osmosis base membranes.

[0004] Although some technical solutions for preparing reverse osmosis membranes using polyethylene membranes have been formed in the prior art, these technical solutions still have room for improvement in terms of both industrial feasibility and flux improvement. Summary of the invention

[0005] In view of the shortcomings of the prior art, the object of the present invention is to provide a high-flux polyethylene-based reverse osmosis membrane, which has the characteristics of high flux, high desalination rate and resistance to back pressure.

[0006] Another object of the present invention is to provide a method for preparing the high-flux polyethylene-based reverse osmosis membrane, which has the characteristics of simple operation and easy industrial production.

[0007] Another object of the present invention is to provide the use of the high-flux polyethylene-based reverse osmosis membrane in a water treatment component or device, and in a water treatment method.

[0008] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0009] The first aspect of the present invention is to provide a high-flux polyethylene-based reverse osmosis membrane, which includes a hydrophilized polyethylene porous support layer and a polyamide desalination layer, and a polyhydroxy polymer intermediate layer containing a multi-molecular channel between the hydrophilized polyethylene porous support layer and the polyamide desalination layer;

[0010] The polyhydroxy polymer intermediate layer of the multi-molecular channel is formed by cross-linking reaction of cyclodextrin and dialdehyde compound under the action of acid catalyst.

[0011] In the present invention, the cyclodextrin is a polyhydroxylated, cyclic oligosaccharide selected from one or more of α-cyclodextrin, β-cyclodextrin, γ-cyclodextrin, 2,6-di-O-methyl-β-cyclodextrin, maltose cyclodextrin, (2-hydroxypropyl)-γ-cyclodextrin, and hydroxyethyl-β-cyclodextrin, preferably α-cyclodextrin;

[0012] The dialdehyde compound is selected from aromatic, aliphatic, or alicyclic compounds containing two aldehyde functional groups, preferably one or more of glyoxal, malondialdehyde, glutaraldehyde, o-phthalaldehyde, diphenylglyoxal, 2-(4-chlorophenyl) malondialdehyde, and 2-cyclopropyl malondialdehyde, more preferably glutaraldehyde;

[0013] The acid catalyst is one or more of an inorganic acid or an organic acid, preferably one or more of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, acetic acid, oxalic acid, citric acid, camphorsulfonic acid, isethionic acid, and ethylsulfonic acid, more preferably hydrochloric acid.

[0014] In the present invention, the polyamide desalination layer is obtained by interfacial polymerization of an aqueous phase containing a compound having two or more active amino groups and an organic phase containing a multifunctional acyl halide;

[0015] Wherein, the compound having two or more active amino groups in the aqueous phase can be any multifunctional amine, preferably a compound having a functionality of 2;

[0016] The compound having two or more active amino groups is selected from one or more of aromatic multifunctional amines, aliphatic multifunctional amines, and alicyclic multifunctional amines;

[0017] The aromatic multifunctional amine is selected from 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-diaminoanisyl, amphenol, and xylenediamine;

[0018] The aliphatic multifunctional amine is selected from one or more of ethylenediamine, propylenediamine, and tris(2-aminoethyl)amine;

[0019] The alicyclic multifunctional amine is selected from one or more of 1,3-diaminocyclohexane, 1,2-diaminocyclohexane, 1,4-diaminocyclohexane, piperazine, 2,5-dimethylpiperazine and 4-aminomethylpiperazine;

[0020] The compound having two or more active amino groups is preferably m-phenylenediamine.

[0021] Wherein, the polyfunctional acyl halide in the organic phase is selected from one or more of aromatic polyfunctional acyl halide, aliphatic polyfunctional acyl halide, and alicyclic polyfunctional acyl halide;

[0022] The aromatic multifunctional acyl halide is selected from one or more of trimesoyl chloride, terephthaloyl chloride, isophthaloyl chloride, biphenyl dicarboxylic acid chloride, naphthalene dicarboxylic acid dichloride, benzene trisulfonyl chloride, benzene disulfonyl chloride, and monochlorosulfonyl benzene dicarboxylic acid chloride;

[0023] The aliphatic multifunctional acyl halide is selected from one or more of propane tricarboxylic acid chloride, butane tricarboxylic acid chloride, pentane tricarboxylic acid chloride, glutaryl halide, and adipoyl halide;

[0024] The alicyclic polyfunctional acyl halide is selected from one or more of cyclopropanetricarboxylic acid chloride, cyclobutanetetracarboxylic acid chloride, cyclopentanetricarboxylic acid chloride, cyclopentanetetracarboxylic acid chloride, cyclohexanetricarboxylic acid chloride, tetrahydrofurantetracarboxylic acid chloride, cyclopentanedicarboxylic acid chloride, cyclobutanedicarboxylic acid chloride, cyclohexanedicarboxylic acid chloride, and tetrahydrofurandicarboxylic acid chloride;

[0025] The polyfunctional acyl halide is preferably trimesoyl chloride.

[0026] In the present invention, the hydrophilized polyethylene porous support layer is a hydrophilized polyethylene porous membrane, which is a hydrophilized porous support membrane obtained by treating a polyethylene porous membrane with low-pressure plasma, and has a pore size of 5-100 nm, preferably 20-40 nm.

[0027] The hydrophilization of the polyethylene porous membrane of the present invention can be prepared by using the existing known technology in the art, and is not particularly limited to this. Usually, the hydrophilized polyethylene membrane is obtained by treating the polyethylene membrane with low-pressure plasma treatment technology, for example, it can be prepared by the method disclosed in patent CN109126483A.

[0028] The present invention unexpectedly discovered during the experiment that the use of low-pressure plasma to treat the polyethylene-based membrane to make it hydrophilic is very likely to produce crack defects on the membrane surface. If it is directly applied to the preparation of reverse osmosis membranes, it is difficult to obtain a high desalination rate. Further, the cross-linked PVA with a linear molecular chain structure is coated on the treated polyethylene-based membrane with crack defects to prepare a reverse osmosis membrane. Although the desalination rate is improved, it is difficult to obtain a high flux due to the large resistance of the cross-linked PVA with narrow molecular gaps to the transmission of water molecules. However, by coating a mixed solution of cyclodextrin, a dialdehyde compound, and an acid catalyst on the hydrophilized polyethylene porous support layer treated with the above-mentioned low-pressure plasma and heating the reaction to generate an intermediate layer, and then preparing a reverse osmosis membrane, the flux and desalination rate can be significantly improved. Analysis of the reason may be that the cyclodextrin with a ring structure of multiple hydroxyl groups and large molecular gaps can effectively build water molecule channels, reduce the permeation resistance of the intermediate layer to water molecules, and thus give the intermediate layer a higher water flux. The cross-linking reaction with the dialdehyde compound during the heating process can, on the one hand, cover the crack defects on the membrane surface at a lower coating amount, thereby increasing the desalination rate of the composite membrane and improving the back pressure resistance of the composite membrane; on the other hand, the cross-linked cyclodextrin gives the intermediate layer a long service life, ensuring the stability of the performance of the composite membrane during actual operation.

[0029] The multi-molecular channel polyhydroxy polymer intermediate layer introduced in the present invention can not only increase the bonding force between the reverse osmosis polyamide desalination layer and the polysulfone support layer, making it more resistant to the back pressure caused by shutdown, but also has high water permeability and high salt removal performance at a low operating pressure of 0.4-0.9MPa, and is particularly suitable for long-term stable desalination treatment of tap water, light salt water, etc.

[0030] The second aspect of the present invention is to provide a method for preparing the aforementioned high-flux polyethylene-based reverse osmosis membrane, comprising the following steps:

[0031] 1) coating a mixed solution containing cyclodextrin, a dialdehyde compound and an acid catalyst on a hydrophilized polyethylene porous membrane, draining off excess solution on the surface, heating to cause a cross-linking reaction to form an intermediate layer, and obtaining a hydrophilized polyethylene porous support membrane with an intermediate layer;

[0032] 2) soaking the hydrophilized polyethylene porous support membrane with the intermediate layer prepared in step 1) in an infiltration liquid, and then washing it in water;

[0033] 3) soaking the hydrophilized polyethylene porous support membrane with the intermediate layer after the infiltration in step 2) in an aqueous phase containing a compound having more than two active amino groups, then removing excess aqueous phase on the surface, and then contacting with an organic phase containing multifunctional acyl halides to perform an interfacial polymerization reaction, and then removing excess liquid and drying to obtain a high-flux polyethylene-based reverse osmosis membrane.

[0034] In the preparation method of the present invention, the mixed solution coated on the hydrophilized polyethylene porous membrane in step 1) comprises the following weight percentages: cyclodextrin 0.01-1.0wt%, preferably 0.1-0.3wt%; dialdehyde compound 0.005-0.5wt%, preferably 0.05-0.2wt%; acid catalyst 0.01-1wt%, preferably 0.1-0.5wt%; and the rest is water.

[0035] In the preparation method of the present invention, the coating amount of the mixed solution on the hydrophilized polyethylene porous membrane in step 1) is sufficient to evenly cover the membrane surface, and the present invention does not make any specific limitation.

[0036] In the preparation method of the present invention, the cross-linking reaction in step 1) is carried out at a temperature of 40-120° C., preferably 50-80° C., and for a time of 1-5 min, preferably 2-4 min.

[0037] In the preparation method of the present invention, the infiltration liquid in step 2) is an alcohol compound, preferably a C1-C8 alcohol compound, more preferably at least one of isopropanol, ethanol and methanol, and most preferably ethanol.

[0038] In the preparation method of the present invention, the soaking time of step 2) is 0.1-5 min, preferably 1-3 min.

[0039] In the preparation method of the present invention, in step 3), the mass concentration of the compound having two or more active amino groups in the aqueous phase is 1.5-5wt%, preferably 2-4wt%.

[0040] In the preparation method of the present invention, the mass concentration of the multifunctional acyl halide in the organic phase of step 3) is 0.1-0.4wt%, preferably 0.1-0.2wt%;

[0041] The organic phase further comprises an organic solvent, which is selected from at least one of n-pentane, n-hexane, n-decane, isoparH, isoparG, and isoparL, preferably isoparG.

[0042] In the preparation method of the present invention, the contacting in step 3) is performed to carry out an interfacial polymerization reaction for a time of 10-100 s, preferably 30-60 s.

[0043] The third aspect of the present invention is to provide an application of the high-flux polyethylene-based reverse osmosis membrane described above, wherein the high-flux polyethylene-based reverse osmosis membrane is applied to a water treatment component or device, and / or applied to a water treatment method.

[0044] The water treatment component or device may be any component or device installed with the high-flux polyethylene-based reverse osmosis membrane of the present invention that can be used in a water treatment process. The "used in a water treatment component or device" includes components or device products installed with the high-flux polyethylene-based reverse osmosis membrane of the present invention, and also includes products used to prepare such components or devices. The component may be, for example, a spiral membrane component and a disc-tube flat membrane component. The device may be, for example, a household / commercial reverse osmosis water purifier, an industrial water supply reverse osmosis pure water device, etc.

[0045] The water treatment method may be, for example, a method for producing drinking water, an industrial water supply, or the like.

[0046] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0047] (1) The reverse osmosis membrane provided by the present invention has the characteristics of high flux and high desalination rate. Under the test conditions known in the industry for treating 250ppm sodium chloride and 0.41MPa, the permeation flux is 45-50L / (m 2 h), the sodium chloride desalination rate is in the range of 96-98%, which can well meet the application of household water purifiers and office water dispensers, and greatly reduce the wastewater discharge of reverse osmosis concentrated water.

[0048] (2) The method for preparing a high-flux polyethylene-based reverse osmosis membrane provided by the present invention has lower manufacturing costs than the conventional method for preparing a reverse osmosis membrane using PET non-woven fabric and polysulfone-based membrane. The preparation method of the present invention is also easy to industrialize and produce.

[0049] (3) The present invention prepares a reverse osmosis membrane by coating a mixed solution of cyclodextrin, an acid catalyst and a dialdehyde compound on a hydrophilized polyethylene porous support layer and heating the mixed solution to react to generate an intermediate layer. In addition, the flux and desalination rate can be significantly improved. In addition, the crack defects on the surface of the polyethylene-based membrane caused by low-pressure plasma treatment can be covered at a lower coating amount of the intermediate layer, thereby improving the back pressure resistance and service life of the composite membrane. DETAILED DESCRIPTION

[0050] The present invention is further described below by means of specific examples. The examples described in the present invention are only used to illustrate the present invention and do not limit the scope of the present invention.

[0051] Unless otherwise specified, the raw materials used in the following examples or comparative examples are all commercially available industrial grade conventional raw materials. The main raw material information is shown in the following Table 1:

[0052] Table 1. Main raw material information

[0053]

[0054] Hydrophilization treatment of the polyethylene porous membrane: The treatment power of the low-pressure oxygen plasma is 50 W, the treatment pressure is 25 Pa, and the treatment time is 180 s. The polyethylene porous membrane is treated with low-pressure plasma, and then the treated membrane is stored stably for 3 days to obtain a hydrophilized polyethylene porous support membrane.

[0055] The main performance testing methods used in the embodiments and comparative examples of the present invention are as follows:

[0056] 1. Evaluation of salt rejection and permeate flux

[0057] Salt rejection rate and permeate flux are two important parameters for evaluating the separation performance of reverse osmosis membranes.

[0058] The desalination rate (R) is defined as: under certain operating conditions, the salt concentration of the feed solution (C f ) and the salt concentration in the permeate (C p ) and then divided by the feed solution salt concentration (C f ), as shown in formula (1).

[0059]

[0060] Permeation flux is defined as the volume of water that passes through a unit membrane area per unit time under certain operating conditions, and its unit is L / (m 2 h).

[0061] The operating conditions used in the reverse osmosis membrane performance measurement in the present invention are: the feed liquid is a 250 ppm sodium chloride aqueous solution, the solution pH is 7.0±0.5, the operating pressure is 0.41 MPa, and the operating temperature is 25°C.

[0062] 2. Evaluation of back pressure resistance performance

[0063] The back pressure resistance performance evaluation is used to evaluate the bonding strength between the polyamide desalination layer and the polysulfone support layer. For the reverse osmosis membrane back pressure, by comparing the change in the reverse osmosis membrane desalination rate before and after the back pressure test, the back pressure resistance performance of the reverse osmosis membrane is characterized, and then the bonding strength between the polyamide desalination layer and the polysulfone porous support layer is indirectly measured. The specific steps are as follows:

[0064] (1) Take a reverse osmosis membrane and place it into a membrane tank with the desalination layer on one side contacting the water inlet side according to the normal test method. Test its desalination rate R0 at 0.41 MPa.

[0065] (2) Take out the reverse osmosis membrane from the membrane pool and install it in reverse so that the desalination layer contacts the permeable side. Apply reverse pressure to the reverse osmosis membrane at an ultimate pressure of 1.05 MPa.

[0066] (3) After the reverse osmosis membrane is removed from the membrane pool, the salt rejection rate is tested again according to the method in step (1) and recorded as R1. The salt rejection rate difference ΔR before and after the reverse osmosis membrane is back-pressurized is calculated as shown in formula (2).

[0067] ΔR=R1-R0 Formula (2)

[0068] 3. Long-term operation performance evaluation

[0069] Long-term operation performance is mainly used to test the stability of the long-term operation performance of the composite membrane. The present invention focuses on the change in desalination rate to evaluate the service life of the intermediate layer. The specific steps are as follows: (23%)

[0070] (1) The feed liquid is a 250 ppm sodium chloride aqueous solution, the solution pH is 7.0±0.5, the operating pressure is 0.41 MPa, and the operating temperature is 25°C. The initial desalination rate Ra is tested.

[0071] (2) After 100 hours of continuous operation, the test ends with the desalination rate Rb. The long-term operation performance of the reverse osmosis membrane, i.e., the desalination rate difference, is calculated as shown in formula (3).

[0072] ΔR'=Ra-Rb Formula (3)

[0073] Example 1

[0074] The steps of preparing a high flux polyethylene-based reverse osmosis membrane are as follows:

[0075] 1) A mixed solution containing cyclodextrin, a dialdehyde compound and an acid catalyst is prepared, wherein the weight percentage composition is as follows: 1.0 wt % of α-cyclodextrin, 0.005 wt % of glutaraldehyde, 0.01 wt % of hydrochloric acid (calculated as HCl therein), and the rest is water.

[0076] preparing an aqueous phase containing m-phenylenediamine at a concentration of 5 wt %;

[0077] An organic phase containing trimesoyl chloride is prepared with a concentration of 0.1 wt % and the organic solvent is isoparG;

[0078] 2) 100 g of the mixed solution prepared in step 1) was evenly coated on a hydrophilized polyethylene porous membrane with a size of 12 cm×16 cm, and the excess solution on the surface was removed by draining for 30 seconds, and the membrane was heated to 120° C. in an oven for a cross-linking reaction for 1 minute to form an intermediate layer, and then dried to obtain a hydrophilized polyethylene porous support membrane with an intermediate layer;

[0079] 3) soaking the hydrophilized polyethylene porous support membrane with an intermediate layer prepared in step 2) in an ethanol soaking solution for 5 minutes, and then placing it in pure water to rinse the soaking solution in the membrane, thereby obtaining a polyethylene porous support membrane with an intermediate layer after soaking treatment;

[0080] 4) The hydrophilized polyethylene porous support membrane with an intermediate layer after infiltration in step 3) is immersed in 500g of the aqueous phase prepared in step 1), and the excess aqueous phase on the surface is removed after being taken out, and then coated with the organic phase prepared in step 1), and the cross-linking reaction is performed for 100s to form a polyamide composite membrane, and then the excess liquid is removed and dried to obtain a high-flux polyethylene-based reverse osmosis membrane.

[0081] The salt rejection rate, permeate flux, back pressure resistance and long-term operation performance of the reverse osmosis membrane were evaluated, and the results are shown in Table 1.

[0082] Example 2

[0083] The steps of preparing a high flux polyethylene-based reverse osmosis membrane are as follows:

[0084] 1) A mixed solution containing cyclodextrin, a dialdehyde compound and an acid catalyst is prepared, wherein the weight percentage composition is as follows: 0.01 wt % of α-cyclodextrin, 0.5 wt % of glutaraldehyde, 1 wt % of hydrochloric acid (calculated as HCl therein), and the rest is water.

[0085] preparing an aqueous phase containing m-phenylenediamine at a concentration of 2 wt %;

[0086] An organic phase containing trimesoyl chloride is prepared with a concentration of 0.4 wt % and the organic solvent is isoparG;

[0087] 2) 100 g of the mixed solution prepared in step 1) was evenly coated on a hydrophilized polyethylene porous membrane with a size of 12 cm×16 cm, and the excess solution on the surface was removed by draining for 30 seconds, and cross-linking reaction was carried out in an oven at 40° C. for 5 minutes to form an intermediate layer, and drying was performed to obtain a hydrophilized polyethylene porous support membrane with an intermediate layer;

[0088] 3) soaking the hydrophilized polyethylene porous support membrane with an intermediate layer prepared in step 2) in an ethanol soaking solution for 0.1 min, and then placing it in pure water to rinse the soaking solution in the membrane, thereby obtaining a polyethylene porous support membrane with an intermediate layer after soaking treatment;

[0089] 4) The hydrophilized polyethylene porous support membrane with an intermediate layer after infiltration in step 3) is immersed in 500g of the aqueous phase prepared in step 1), and the excess aqueous phase on the surface is removed after being taken out, and then coated with the organic phase prepared in step 1), and the cross-linking reaction is carried out for 10s to form a polyamide composite membrane, and then the excess liquid is removed and dried to obtain a high-flux polyethylene-based reverse osmosis membrane.

[0090] The salt rejection rate, permeate flux, back pressure resistance and long-term operation performance of the reverse osmosis membrane were evaluated, and the results are shown in Table 1.

[0091] Example 3

[0092] The steps of preparing a high flux polyethylene-based reverse osmosis membrane are as follows:

[0093] 1) A mixed solution containing cyclodextrin, a dialdehyde compound and an acid catalyst is prepared, wherein the weight percentage composition is as follows: 0.2 wt % of α-cyclodextrin, 0.1 wt % of glutaraldehyde, 0.1 wt % of hydrochloric acid (calculated as HCl therein), and the rest is water.

[0094] preparing an aqueous phase containing m-phenylenediamine at a concentration of 3 wt %;

[0095] An organic phase containing trimesoyl chloride is prepared at a concentration of 0.16 wt % and the organic solvent is isoparG;

[0096] 2) 100 g of the mixed solution prepared in step 1) was evenly coated on a hydrophilized polyethylene porous membrane with a size of 12 cm×16 cm, and the excess solution on the surface was removed by draining for 30 seconds, and the membrane was heated to 60° C. in an oven for a cross-linking reaction for 3 minutes to form an intermediate layer, and dried to obtain a hydrophilized polyethylene porous support membrane with an intermediate layer;

[0097] 3) soaking the hydrophilized polyethylene porous support membrane with an intermediate layer prepared in step 2) in an ethanol soaking solution for 2 minutes, and then placing it in pure water to rinse the soaking solution in the membrane, thereby obtaining a polyethylene porous support membrane with an intermediate layer after soaking treatment;

[0098] 4) The hydrophilized polyethylene porous support membrane with an intermediate layer after being soaked in step 3) is immersed in 500g of the aqueous phase prepared in step 1), and the excess aqueous phase on the surface is removed after being taken out, and then coated with the organic phase prepared in step 1), and the cross-linking reaction is performed for 40s to form a polyamide composite membrane, and then the excess liquid is removed and dried to obtain a high-flux polyethylene-based reverse osmosis membrane.

[0099] The salt rejection rate, permeate flux, back pressure resistance and long-term operation performance of the reverse osmosis membrane were evaluated, and the results are shown in Table 1.

[0100] Example 4

[0101] The steps of preparing a high flux polyethylene-based reverse osmosis membrane are as follows:

[0102] 1) preparing a mixed solution containing cyclodextrin, a dialdehyde compound and an acid catalyst, wherein the weight percentage composition is: 0.2wt% of β-cyclodextrin, 0.1wt% of glyoxal, 0.3wt% of citric acid, and the rest is water.

[0103] Prepare an aqueous phase containing m-phenylenediamine and o-phenylenediamine, wherein the concentration of m-phenylenediamine is 2.5wt% and the concentration of o-phenylenediamine is 0.2wt%;

[0104] An organic phase containing trimesoyl chloride and isophthaloyl chloride is prepared, wherein the concentration of trimesoyl chloride is 0.15wt%, the concentration of isophthaloyl chloride is 0.03wt%, and the organic solvent is n-decane;

[0105] 2) 100 g of the mixed solution prepared in step 1) was evenly coated on a hydrophilized polyethylene porous membrane with a size of 12 cm×16 cm, and the excess solution on the surface was removed by draining for 30 seconds, and the mixture was heated to 50° C. in an oven for a cross-linking reaction for 2 minutes to form an intermediate layer, and dried to obtain a hydrophilized polyethylene porous support membrane with an intermediate layer;

[0106] 3) soaking the hydrophilized polyethylene porous support membrane with an intermediate layer prepared in step 2) in an isopropanol soaking solution for 3 minutes, and then placing it in pure water to rinse the soaking solution in the membrane, thereby obtaining a polyethylene porous support membrane with an intermediate layer after soaking treatment;

[0107] 4) The hydrophilized polyethylene porous support membrane with an intermediate layer after infiltration in step 3) is immersed in 500g of the aqueous phase prepared in step 1), and the excess aqueous phase on the surface is removed after being taken out, and then coated with the organic phase prepared in step 1), and the cross-linking reaction is performed for 50s to form a polyamide composite membrane, and then the excess liquid is removed and dried to obtain a high-flux polyethylene-based reverse osmosis membrane.

[0108] The salt rejection rate, permeate flux, back pressure resistance and long-term operation performance of the reverse osmosis membrane were evaluated, and the results are shown in Table 1.

[0109] Comparative Example 1

[0110] A polyethylene-based reverse osmosis membrane was prepared by referring to the method in Example 3, except that in step 1), cyclodextrin was not added to the mixed solution, and other parameters and operations remained unchanged to obtain a polyethylene-based reverse osmosis membrane.

[0111] The salt rejection rate, permeate flux, back pressure resistance and long-term operation performance of the reverse osmosis membrane were evaluated, and the results are shown in Table 1.

[0112] Comparative Example 2

[0113] A polyethylene-based reverse osmosis membrane was prepared by referring to the method in Example 3, except that in step 1), no acid was added to the mixed solution, and other parameters and operations remained unchanged to obtain a polyethylene-based reverse osmosis membrane.

[0114] The salt rejection rate, permeate flux, back pressure resistance and long-term operation performance of the reverse osmosis membrane were evaluated, and the results are shown in Table 1.

[0115] Comparative Example 3

[0116] A polyethylene reverse osmosis membrane was prepared by referring to the method in Example 3, except that in step 1), no dialdehyde was added to the mixed solution, and other parameters and operations remained unchanged to obtain a polyethylene reverse osmosis membrane.

[0117] The salt rejection rate, permeate flux, back pressure resistance and long-term operation performance of the reverse osmosis membrane were evaluated, and the results are shown in Table 1.

[0118] Comparative Example 4

[0119] A polyethylene-based reverse osmosis membrane was prepared by referring to the method in Example 3, except that in steps 1) and 2), the mixed solution was not prepared and coated, and other parameters and operations remained unchanged to obtain a polyethylene-based reverse osmosis membrane.

[0120] The salt rejection rate, permeate flux, back pressure resistance and long-term operation performance of the reverse osmosis membrane were evaluated, and the results are shown in Table 1.

[0121] Comparative Example 5

[0122] A polyethylene reverse osmosis membrane was prepared by referring to the method in Example 3, except that in steps 1) and 2), the cyclodextrin in the mixed solution was replaced by PVA1788 of equal concentration, and other parameters and operations remained unchanged to obtain a polyethylene reverse osmosis membrane.

[0123] The salt rejection rate, permeate flux, back pressure resistance and long-term operation performance of the reverse osmosis membrane were evaluated, and the results are shown in Table 1.

[0124] Comparative Example 6

[0125] A polyethylene-based reverse osmosis membrane was prepared by referring to the method in Example 3, except that in steps 1) and 2), the mixed solution was replaced by an aqueous solution of PVA1788, and other parameters and operations remained unchanged to obtain a polyethylene-based reverse osmosis membrane.

[0126] The salt rejection rate, permeate flux, back pressure resistance and long-term operation performance of the reverse osmosis membrane were evaluated, and the results are shown in Table 1.

[0127] Comparative Example 7

[0128] A polyethylene-based reverse osmosis membrane was prepared by referring to the method in Example 3, except that the infiltration treatment in step 3) was not performed, and other parameters and operations remained unchanged to obtain a polyethylene-based reverse osmosis membrane.

[0129] The salt rejection rate, permeate flux, back pressure resistance and long-term operation performance of the reverse osmosis membrane were evaluated, and the results are shown in Table 1.

[0130] Table 1. Evaluation results of products in Examples 1-3 and Comparative Examples 1-7

[0131]

[0132]

[0133] The experimental results in Table 1 show that the reverse osmosis membrane obtained by modifying the polyethylene-based membrane with the intermediate layer of the present invention has significantly higher flux and desalination rate, the polyamide amine has good bonding strength with the support layer, and exhibits stable long-cycle operation performance.

[0134] The above is only a preferred embodiment of the present invention. It should be pointed out that ordinary technicians in this field can make several improvements and supplements without departing from the method of the present invention. These improvements and supplements should also be regarded as the scope of protection of the present invention.

Claims

1. A high flux polyethylene-based reverse osmosis membrane, characterized in that: It includes a hydrophilized polyethylene porous support layer and a polyamide desalination layer, and a polyhydroxy polymer intermediate layer with multi-molecular channels is contained between the hydrophilized polyethylene porous support layer and the polyamide desalination layer; The polyhydroxy polymer intermediate layer of the multi-molecular channel is formed by cross-linking reaction of cyclodextrin and dialdehyde compound under the action of acid catalyst; The method for preparing the high-flux polyethylene-based reverse osmosis membrane comprises the following steps: 1) coating a mixed solution containing cyclodextrin, a dialdehyde compound and an acid catalyst on a hydrophilized polyethylene porous membrane, draining off excess solution on the surface, heating to cause a cross-linking reaction to form an intermediate layer, and obtaining a hydrophilized polyethylene porous support membrane with an intermediate layer; 2) soaking the hydrophilized polyethylene porous support membrane with the intermediate layer prepared in step 1) in an infiltration liquid, and then washing it in water; 3) soaking the hydrophilized polyethylene porous support membrane with the intermediate layer after the infiltration in step 2) in an aqueous phase containing a compound having more than two active amino groups, then removing excess aqueous phase on the surface, and then contacting with an organic phase containing multifunctional acyl halides to perform an interfacial polymerization reaction, and then removing excess liquid and drying to obtain a high-flux polyethylene-based reverse osmosis membrane.

2. The high flux polyethylene-based reverse osmosis membrane according to claim 1, characterized in that: The cyclodextrin is selected from one or more of α-cyclodextrin, β-cyclodextrin, γ-cyclodextrin, 2,6-di-O-methyl-β-cyclodextrin, maltose cyclodextrin, (2-hydroxypropyl)-γ-cyclodextrin, and hydroxyethyl-β-cyclodextrin; The dialdehyde compound is selected from aromatic, aliphatic, or alicyclic compounds containing two aldehyde functional groups; The acid catalyst is one or more of an inorganic acid or an organic acid.

3. The high flux polyethylene-based reverse osmosis membrane according to claim 2, characterized in that: The dialdehyde compound is selected from one or more of glyoxal, malondialdehyde, glutaraldehyde, o-phthalaldehyde, diphenylglyoxal, 2-(4-chlorophenyl) malondialdehyde, and 2-cyclopropyl malondialdehyde.

4. The high flux polyethylene-based reverse osmosis membrane according to claim 2, characterized in that: The acid catalyst is one or more of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, acetic acid, oxalic acid, citric acid, camphorsulfonic acid, isethionic acid, and ethylsulfonic acid.

5. The high flux polyethylene-based reverse osmosis membrane according to claim 1, characterized in that: The polyamide desalination layer is obtained by interfacial polymerization of an aqueous phase containing a compound having two or more active amino groups and an organic phase containing a multifunctional acyl halide; Wherein, the compound having two or more active amino groups in the aqueous phase is selected from one or more of aromatic multifunctional amines, aliphatic multifunctional amines, and alicyclic multifunctional amines; The aromatic multifunctional amine is selected from 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-diaminoanisyl, amphenol, and xylenediamine; The aliphatic multifunctional amine is selected from one or more of ethylenediamine, propylenediamine, and tris(2-aminoethyl)amine; The alicyclic multifunctional amine is selected from one or more of 1,3-diaminocyclohexane, 1,2-diaminocyclohexane, 1,4-diaminocyclohexane, piperazine, 2,5-dimethylpiperazine and 4-aminomethylpiperazine; Wherein, the polyfunctional acyl halide in the organic phase is selected from one or more of aromatic polyfunctional acyl halide, aliphatic polyfunctional acyl halide, and alicyclic polyfunctional acyl halide; The aromatic multifunctional acyl halide is selected from one or more of trimesoyl chloride, terephthaloyl chloride, isophthaloyl chloride, biphenyl dicarboxylic acid chloride, naphthalene dicarboxylic acid dichloride, benzene trisulfonyl chloride, benzene disulfonyl chloride, and monochlorosulfonyl benzene dicarboxylic acid chloride; The aliphatic multifunctional acyl halide is selected from one or more of propane tricarboxylic acid chloride, butane tricarboxylic acid chloride, pentane tricarboxylic acid chloride, glutaryl halide, and adipoyl halide; The alicyclic polyfunctional acyl halide is selected from one or more of cyclopropanetricarboxylic acid chloride, cyclobutanetetracarboxylic acid chloride, cyclopentanetricarboxylic acid chloride, cyclopentanetetracarboxylic acid chloride, cyclohexanetricarboxylic acid chloride, tetrahydrofurantetracarboxylic acid chloride, cyclopentanedicarboxylic acid chloride, cyclobutanedicarboxylic acid chloride, cyclohexanedicarboxylic acid chloride, and tetrahydrofurandicarboxylic acid chloride.

6. The high flux polyethylene-based reverse osmosis membrane according to claim 5, characterized in that: The functionality of the compound having two or more active amino groups is 2.

7. The high flux polyethylene-based reverse osmosis membrane according to claim 5, characterized in that: The compound having more than two active amino groups is m-phenylenediamine.

8. The high flux polyethylene-based reverse osmosis membrane according to claim 5, characterized in that: The multifunctional acyl halide is trimesoyl chloride.

9. The high flux polyethylene-based reverse osmosis membrane according to claim 1, characterized in that: The hydrophilized polyethylene porous support layer is a hydrophilized polyethylene porous membrane, which is a hydrophilized porous support membrane obtained by treating a polyethylene porous membrane with low-pressure plasma, and has a pore size of 5-100 nm.

10. The high flux polyethylene-based reverse osmosis membrane according to claim 9, characterized in that: The pore diameter is 20-40 nm.

11. A method for preparing a high-flux polyethylene-based reverse osmosis membrane according to any one of claims 1 to 10, characterized in that: The following steps are involved: 1) coating a mixed solution containing cyclodextrin, a dialdehyde compound and an acid catalyst on a hydrophilized polyethylene porous membrane, draining off excess solution on the surface, heating to cause a cross-linking reaction to form an intermediate layer, and obtaining a hydrophilized polyethylene porous support membrane with an intermediate layer; 2) soaking the hydrophilized polyethylene porous support membrane with the intermediate layer prepared in step 1) in an infiltration liquid, and then washing it in water; 3) soaking the hydrophilized polyethylene porous support membrane with the intermediate layer after the infiltration in step 2) in an aqueous phase containing a compound having more than two active amino groups, then removing excess aqueous phase on the surface, and then contacting with an organic phase containing multifunctional acyl halides to perform an interfacial polymerization reaction, and then removing excess liquid and drying to obtain a high-flux polyethylene-based reverse osmosis membrane.

12. The preparation method according to claim 11, characterized in that: Step 1) The mixed solution coated on the hydrophilized polyethylene porous membrane comprises: 0.01-1.0wt% of cyclodextrin, 0.005-0.5wt% of dialdehyde compound, 0.01-1wt% of acid catalyst, and the rest is water; The cross-linking reaction in step 1) is carried out at a temperature of 40-120° C. and for a time of 1-5 min.

13. The preparation method according to claim 12, characterized in that: The mixed solution comprises the following components in percentage by weight: 0.1-0.3 wt % of cyclodextrin, 0.05-0.2 wt % of dialdehyde compound, 0.1-0.5 wt % of acid catalyst, and the rest is water.

14. The preparation method according to claim 12, characterized in that: The cross-linking reaction is carried out at a temperature of 50-80° C. and for a time of 2-4 minutes.

15. The preparation method according to claim 11, characterized in that: Step 2) the infiltration liquid is an alcohol compound; The infiltration time of step 2) is 0.1-5min.

16. The preparation method according to claim 15, characterized in that: The infiltration liquid is a C1-C8 alcohol compound.

17. The preparation method according to claim 16, characterized in that: The infiltration liquid is at least one of isopropanol, ethanol and methanol.

18. The preparation method according to claim 15, characterized in that: The infiltration time is 1-3 minutes.

19. The preparation method according to claim 11, characterized in that: Step 3) the aqueous phase, wherein the mass concentration of the compound having two or more active amino groups is 1.5-5wt%; Step 3) the organic phase, wherein the mass concentration of the multifunctional acyl halide is 0.1-0.4wt%; The organic phase further comprises an organic solvent, and the organic solvent is selected from at least one of n-pentane, n-hexane, n-decane, isoparH, isoparG, and isoparL; Step 3) The contacting is performed to carry out an interfacial polymerization reaction for a time of 10-100 seconds.

20. The preparation method according to claim 19, characterized in that: The mass concentration of the compound having more than two active amino groups is 2-4 wt %.

21. The preparation method according to claim 19, characterized in that: The mass concentration of the multifunctional acyl halide is 0.1-0.2 wt %.

22. The preparation method according to claim 19, characterized in that: The contacting is performed to carry out an interfacial polymerization reaction for 30-60 seconds.

23. Use of the high-flux polyethylene-based reverse osmosis membrane according to any one of claims 1 to 10 or the high-flux polyethylene-based reverse osmosis membrane prepared by the method according to any one of claims 11 to 22 in a water treatment component or device, and / or in a water treatment method.

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