Anti-pollution composite reverse osmosis membrane and preparation method thereof

Abstract

The invention discloses an anti-pollution composite reverse osmosis membrane and a preparation method thereof.The preparation method comprises the following steps that a diamine water phase and a triacyl chloride oil phase are subjected to an interfacial polymerization reaction on a base membrane, a polyamide layer is formed, and the polyamide layer contains carboxyl groups; under the action of a catalyst, the carboxyl group reacts with part of hydroxyl groups in amino alcohol, so that the amino alcohol is grafted on the polyamide layer, and the amino alcohol contains at least two hydroxyl groups and at least one amino group; and reacting amino in the amino alcohol grafted on the surface of the polyamide layer with polyaldehyde to generate Schiff base, thereby obtaining the anti-pollution composite reverse osmosis membrane. By adopting a chemical grafting method, grafted functional groups, namely hydroxyl and Schiff base, can stably exist on the surface of a polyamide layer and cannot be washed away by water along with long-time operation; under the synergistic effect of the two functional groups, the reverse osmosis membrane can continuously have high antibacterial performance and anti-pollution performance within a long service life.

Description

Technical Field

[0001] The invention relates to the technical field of membrane separation, and in particular to an anti-pollution composite reverse osmosis membrane and a preparation method thereof. Background Art

[0002] At present, the research on anti-pollution reverse osmosis membrane is mainly divided into two aspects, namely the anti-pollution research of polyamide functional layer and the anti-pollution research of reverse osmosis membrane surface. Among them, the anti-pollution research of polyamide layer mainly adds nano bactericidal particles in the water phase. After the polyamide layer is generated by interfacial polymerization, the nano bactericidal particles play a bactericidal role. The anti-pollution research on the surface of reverse osmosis membrane mainly coats a layer of material such as polyvinyl alcohol (PVA) on the surface of the polyamide layer of the reverse osmosis membrane to improve the smoothness, hydrophilicity, and cleaning resistance of the membrane surface and reduce the amount of charge on the membrane surface, thereby enhancing the anti-pollution ability of the reverse osmosis membrane. However, whether it is nano bactericidal particles or surface coatings, there is a problem of being washed away by water after the reverse osmosis membrane has been running for a long time, which reduces the anti-pollution ability of the membrane. Summary of the invention

[0003] The present invention aims to solve one of the technical problems in the related art at least to a certain extent. To this end, the present invention provides an anti-pollution composite reverse osmosis membrane and a preparation method thereof, wherein the reverse osmosis membrane has high antibacterial and anti-pollution properties over a long service life.

[0004] Specifically, the first aspect of the present invention provides a method for preparing an anti-pollution composite reverse osmosis membrane, comprising the following steps:

[0005] Allowing a diamine aqueous phase and a triacyl chloride oil phase to undergo an interfacial polymerization reaction on the base film to form a polyamide layer, wherein the polyamide layer contains a carboxyl group;

[0006] Under the action of a catalyst, the carboxyl group reacts with part of the hydroxyl groups in the amino alcohol, so that the amino alcohol is grafted onto the polyamide layer, wherein the amino alcohol contains at least 2 hydroxyl groups and at least 1 amino group;

[0007] The amino groups in the amino alcohol grafted on the surface of the polyamide layer are reacted with polyaldehydes to generate Schiff bases, thereby obtaining the anti-pollution composite reverse osmosis membrane.

[0008] The present invention utilizes the carboxyl groups in the polyamide functional layer to graft amino alcohol containing at least two hydroxyl groups and at least one amino group, and further reacts the amino group in the amino alcohol with the aldehyde group to generate a Schiff base with bactericidal function. The grafted hydroxyl group can improve the hydrophilicity of the reverse osmosis membrane and increase the water flux of the membrane. At the same time, the Schiff base has an antibacterial effect. In addition, due to the use of a chemical grafting method, the grafted functional groups (including hydroxyl groups and Schiff base C=N groups) can be stably present on the surface of the polyamide layer and will not be washed away by water during long-term operation. Under the synergistic effect of the above two functional groups, the reverse osmosis membrane can continue to have high antibacterial and anti-fouling properties during a long service life.

[0009] According to some embodiments of the present invention, the amino alcohol containing at least 2 hydroxyl groups and at least 1 amino group includes one or more of serinol, 2-amino-1,4-butanediol, 3-amino-1,5-pentanediol, and 2-amino-1,5-pentanediol. The amino alcohol used in the present invention has a special structure, that is, it contains at least 2 hydroxyl groups and at least 1 amino group, wherein a part of the hydroxyl groups is used to connect with the surface of the polyamide layer, another part of the hydroxyl groups is used to improve the hydrophilicity of the reverse osmosis membrane and increase the operating water flux of the membrane, and the amino group is used to react with the aldehyde group to generate a Schiff base. Optimizing the type of amino alcohol is conducive to promoting the grafting reaction and reducing the difficulty of the grafting reaction. In addition, compared with grafting high molecular weight polyols, grafting small molecule amino alcohols has good water solubility and low toxicity, and the smaller the molecule, the smaller the molecular steric hindrance and the higher the reaction activity, making the grafting reaction easier to occur.

[0010] According to some embodiments of the present invention, the polyaldehyde contains at least two aldehyde groups. A part of the aldehyde groups in the polyaldehyde reacts with at least a part of the amino groups in the amino alcohol to generate a Schiff base with antibacterial effect, thereby improving the antibacterial property of the membrane. In addition, the aldehyde groups that do not participate in the reaction also have a certain antibacterial effect. Therefore, it is preferred to use a polyaldehyde containing more than two aldehyde groups to improve the antibacterial property of the membrane.

[0011] According to some embodiments of the present invention, the polyaldehyde includes a long-chain polyaldehyde containing more than 4 carbon atoms; preferably, the polyaldehyde includes one or more of succindialdehyde, glutaraldehyde, adipaldehyde, and 3-methyl-glutaraldehyde.

[0012] According to some embodiments of the present invention, the catalyst includes one or more of 4-dimethylaminopyridine, 4-pyrrolidinopyridine, and imidazole; the diamine includes one or more of m-phenylenediamine, p-phenylenediamine, and o-phenylenediamine; and the triacyl chloride includes trimesoyl chloride. Selecting a suitable catalyst is conducive to promoting the full progress of the amino alcohol grafting reaction. Selecting diamine and triacyl chloride to prepare polyamide is conducive to the presence of unreacted acyl chloride groups in the polyamide layer, and these acyl chloride groups can be further hydrolyzed into carboxyl groups for grafting amino alcohol.

[0013] According to some embodiments of the present invention, grafting the amino alcohol comprises: dissolving the amino alcohol and a catalyst in a solvent, pouring the resulting solution on the surface of the polyamide layer, and removing the solution after the reaction; preferably, the mass concentration of the amino alcohol is 0.5%-1%; preferably, the mass concentration of the catalyst is 0.03%-0.05%.

[0014] According to some embodiments of the present invention, generating a Schiff base includes: dissolving the polyaldehyde in a solvent, pouring the resulting solution on the surface of the grafted polyamide layer, and removing the solution after the reaction; preferably, dissolving the polyaldehyde and a surfactant together in a solvent; preferably, the surfactant includes one or more of sodium dodecyl sulfate, sodium dodecyl sulfonate, and sodium dodecylbenzene sulfonate; preferably, the mass concentration of the polyaldehyde is 5%-10%; preferably, the mass concentration ratio of the polyaldehyde to the amino alcohol is 10:1-12:1. If the concentration of the polyaldehyde is too high, the polyaldehyde will adhere to the surface of the polyamide layer and need to be removed by multiple washings. On the one hand, this causes a waste of raw materials, and on the other hand, multiple washings will also increase the risk of membrane damage.

[0015] According to some embodiments of the present invention, preparing the polyamide layer comprises: pouring the diamine aqueous phase and the triacyl chloride oil phase sequentially on the surface of the base film, drying after reaction; preferably, the mass concentration ratio of the diamine aqueous phase to the triacyl chloride oil phase is 20:1 to 15:1; preferably, the mass concentration of the diamine aqueous phase is 2%-4%; preferably, the mass concentration of the triacyl chloride oil phase is 0.1%-0.2%. Optimizing the mass concentration ratio of the diamine aqueous phase solution and the triacyl chloride oil phase solution is conducive to making a part of the acyl chloride groups in the triacyl chloride not participate in the interfacial polymerization reaction, but hydrolyzed into carboxyl groups, so as to achieve the grafting of amino alcohol.

[0016] According to some embodiments of the present invention, after the Schiff base is generated, the anti-pollution composite reverse osmosis membrane is heat treated and cleaned; preferably, the heat treatment temperature is 50° C.-70° C. The heat treatment further promotes the reaction and solidifies the polyamide layer, making the performance of the reverse osmosis membrane more stable.

[0017] The second aspect of the present invention provides an anti-pollution composite reverse osmosis membrane obtained by the preparation method of the first aspect of the present invention.

[0018] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. DETAILED DESCRIPTION

[0019] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be understood as limiting the present invention.

[0020] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0021] Herein, the term "comprising" or "including" is an open expression, that is, including the content specified in the present invention, but not excluding other aspects. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0022] At present, the research on anti-pollution reverse osmosis membrane is mainly divided into two aspects, namely the anti-pollution research of polyamide functional layer and the anti-pollution research of reverse osmosis membrane surface. Among them, the anti-pollution research of polyamide layer mainly adds nano bactericidal particles in the water phase. After the polyamide layer is generated by interfacial polymerization, the nano bactericidal particles play a bactericidal role. The anti-pollution research on the surface of reverse osmosis membrane mainly coats a layer of material such as polyvinyl alcohol (PVA) on the surface of the polyamide layer of the reverse osmosis membrane to improve the smoothness, hydrophilicity, and cleaning resistance of the membrane surface and reduce the amount of charge on the membrane surface, thereby enhancing the anti-pollution ability of the reverse osmosis membrane. However, whether it is nano bactericidal particles or surface coatings, there is a problem of being washed away by water after the reverse osmosis membrane has been running for a long time, which reduces the anti-pollution ability of the membrane.

[0023] In order to make the reverse osmosis membrane continue to have high anti-pollution performance throughout the entire service life, the present invention proposes a method for preparing an anti-pollution composite reverse osmosis membrane, using the carboxyl group in the polyamide functional layer to graft amino alcohol containing at least 2 hydroxyl groups and at least 1 amino group, and the amino group in the amino alcohol is further reacted with the aldehyde group to generate a Schiff base with bactericidal function. The grafted hydroxyl group can improve the hydrophilicity of the reverse osmosis membrane and increase the water flux of the membrane. At the same time, the Schiff base has an antibacterial effect. In addition, due to the use of a chemical grafting method, the grafted functional groups (including hydroxyl groups and Schiff base C=N groups) can be stably present on the surface of the polyamide layer and will not be washed away by water during long-term operation. Under the synergistic effect of the above two functional groups, the reverse osmosis membrane can continue to have high antibacterial and anti-pollution properties during a long service life.

[0024] Specifically, the first aspect of the present invention provides a method for preparing an anti-pollution composite reverse osmosis membrane, comprising the following steps:

[0025] Allowing a diamine aqueous phase and a triacyl chloride oil phase to undergo an interfacial polymerization reaction on the base film to form a polyamide layer, wherein the polyamide layer contains a carboxyl group;

[0026] Under the action of a catalyst, the carboxyl group reacts with part of the hydroxyl groups in the amino alcohol, so that the amino alcohol is grafted onto the polyamide layer, wherein the amino alcohol contains at least 2 hydroxyl groups and at least 1 amino group;

[0027] The amino groups in the amino alcohol grafted on the polyamide layer are reacted with polyaldehydes to generate Schiff bases, thereby obtaining the anti-fouling composite reverse osmosis membrane.

[0028] The reaction mechanism of the present invention is as follows: the amino groups of the diamine in the water phase and the acyl chloride groups of the triacyl chloride in the oil phase can undergo interfacial polymerization to generate polyamide, wherein the acyl chloride groups not participating in the interfacial polymerization can be hydrolyzed into carboxyl groups in the presence of water, and the carboxyl groups undergo esterification reaction with part of the hydroxyl groups in the amino alcohol under the action of a catalyst, so that the amino alcohol is grafted on the polyamide layer, and at this time, there are still amino groups and hydroxyl groups not participating in the reaction on the amino alcohol, and the hydroxyl groups not participating in the reaction can improve the hydrophilicity of the membrane and increase the water flux of the membrane; the amino groups can undergo aldehyde-ammonia cross-linking reaction with the aldehyde groups of the polyaldehyde to generate Schiff bases, thereby improving the antibacterial effect of the membrane. Thus, the present invention improves the anti-fouling performance of the membrane by simultaneously improving the hydrophilicity and antibacterial effect of the membrane, and because the polyamide layer is modified by chemical grafting, the surface bonding strength is high, and the protective effect will not be lost due to gradual dissolution in water, thereby achieving long-term anti-fouling performance of the membrane and extending the service life of the reverse osmosis membrane.

[0029] The preparation method of the invention has a simple process, few steps, mild reaction conditions, can react at room temperature, and is suitable for large-scale industrial production applications.

[0030] In some embodiments, the amino alcohol may contain 2, 3, 4, or 5 hydroxyl groups and may contain 1, 2, 3, or 4 amino groups.

[0031] In some embodiments, the amino alcohol containing at least 2 hydroxyl groups and at least 1 amino group includes one or more of serinol, 2-amino-1,4-butanediol, 3-amino-1,5-pentanediol, and 2-amino-1,5-pentanediol. The amino alcohol is soluble in water. The amino alcohol used in the present invention has a special structure, that is, it contains at least 2 hydroxyl groups and at least 1 amino group, wherein a part of the hydroxyl groups is used to connect with the polyamide layer, another part of the hydroxyl groups is used to improve the hydrophilicity of the reverse osmosis membrane and increase the operating water flux of the membrane, and the amino group is used to react with the aldehyde group to generate a Schiff base to provide the membrane with an antibacterial effect. By optimizing the type of amino alcohol, it is beneficial to promote the grafting reaction and reduce the difficulty of the grafting reaction. In addition, compared with the grafting of high molecular weight polyols, the grafted small molecule amino alcohol has good water solubility and low toxicity, and the smaller the molecule, the smaller the molecular steric hindrance and the higher the reaction activity, making the grafting reaction easier to occur. The high molecular weight polyol has a long molecular chain, a reduced water solubility, and a reduced thickness and uniformity of the grafted layer formed, which has a greater impact on the membrane performance, especially the flux.

[0032] In some embodiments, the polyaldehyde contains at least 2 aldehyde groups, for example, 2, 3 or 4 aldehyde groups. A part of the aldehyde groups in the polyaldehyde reacts with at least a part of the amino groups in the amino alcohol to generate a Schiff base with antibacterial effect, thereby improving the antibacterial property of the membrane. In addition, the aldehyde groups that do not participate in the reaction also have a certain antibacterial effect. Therefore, it is preferred to use a polyaldehyde containing more than 2 aldehyde groups to improve the antibacterial property of the membrane.

[0033] In some embodiments, the polyaldehyde comprises a long-chain polyaldehyde comprising more than 4 carbon atoms. For example, the long-chain polyaldehyde may comprise 4, 5, 6, 7 or 8 carbon atoms. The polyaldehyde is preferably soluble in water.

[0034] In some specific embodiments, the polyaldehyde includes one or more of succindialdehyde, glutaraldehyde, adipaldehyde, and 3-methyl-glutaraldehyde.

[0035] In some embodiments, the catalyst includes one or more of 4-dimethylaminopyridine, 4-pyrrolidinopyridine, and imidazole. Selecting a suitable catalyst is conducive to promoting the full progress of the amino alcohol grafting reaction.

[0036] In some embodiments, the diamine includes one or more of m-phenylenediamine, p-phenylenediamine, and o-phenylenediamine; the triacyl chloride includes trimesoyl chloride. Selecting diamine and triacyl chloride to prepare polyamide is conducive to the presence of unreacted acyl chloride groups in the polyamide layer, and these acyl chloride groups can be further hydrolyzed into carboxyl groups for grafting amino alcohol.

[0037] In some embodiments, grafting the amino alcohol comprises: dissolving the amino alcohol and a catalyst in a solvent, pouring the resulting solution on the surface of the polyamide layer, and removing the solution after the reaction.

[0038] In some embodiments, the mass concentration of the amino alcohol may be 0.5%-1%, for example, 0.5%, 0.6%, 0.7%, 0.8%, 0.9% or 1%. Optimizing the concentration of the amino alcohol is conducive to promoting the carboxyl groups on the polyamide layer to fully participate in the reaction, increasing the amount of amino alcohol grafting, and ultimately improving the anti-fouling performance of the membrane.

[0039] The present invention has no particular limitation on the volume of the solution containing amino alcohol and catalyst, as long as it can cover the entire membrane.

[0040] In some embodiments, the solvent includes water. The presence of water can fully hydrolyze the acyl chloride groups in the polyamide layer that do not participate in the interfacial polymerization reaction into carboxyl groups, thereby increasing the number of carboxyl groups to graft more amino alcohols, thereby facilitating the improvement of the hydrophilicity and antibacterial properties of the membrane.

[0041] In some embodiments, the mass concentration of the catalyst may be 0.03%-0.05%, for example, 0.03%, 0.04% or 0.05%. Optimizing the amount of the catalyst is beneficial to promoting the grafting reaction. The reaction time may be within 10 minutes, for example, 2 minutes, 3 minutes, 4 minutes, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes or 10 minutes.

[0042] In some embodiments, generating the Schiff base comprises: dissolving the polyaldehyde in a solvent, pouring the obtained solution on the surface of the grafted polyamide layer, and removing the solution after the reaction.

[0043] In some specific embodiments, the polyaldehyde and the surfactant are dissolved in a solvent together. Adding the surfactant can reduce surface tension, reduce surface energy, increase reactive centers, and accelerate the reaction. The reaction time can be within 10 minutes, such as 2 minutes, 3 minutes, 4 minutes, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, or 10 minutes.

[0044] In some specific embodiments, the surfactant includes one or more of sodium dodecyl sulfate, sodium dodecyl sulfonate, and sodium dodecylbenzene sulfonate.

[0045] In some embodiments, the solvent comprises water.

[0046] In some embodiments, the mass concentration of the polyaldehyde may be 5%-10%, for example, 5%, 6%, 7%, 8%, 9% or 10%. A suitable polyaldehyde concentration is conducive to the Schiff base reaction. If the polyaldehyde concentration is too high, the polyaldehyde will adhere to the surface of the polyamide layer and need to be removed by multiple washings. On the one hand, this causes a waste of raw materials, and on the other hand, multiple washings will also increase the risk of membrane damage. The present invention has no particular restrictions on the volume of the solution containing the polyaldehyde, as long as it can cover the entire membrane.

[0047] In some specific embodiments, the mass concentration ratio of the polyaldehyde to the amino alcohol is 10: 1-12: 1, for example, 10: 1, 10.5: 1, 11: 1, 11.5: 1 or 12: 1. Optimizing the mass concentration ratio of the polyaldehyde to the amino alcohol is beneficial to promoting the Schiff base reaction and improving the antibacterial property.

[0048] In some embodiments, preparing the polyamide layer includes: pouring the diamine aqueous phase and the triacyl chloride oil phase sequentially onto the surface of the base film, and drying after the reaction.

[0049] The poured diamine aqueous phase soaks the base film, and the amino groups and the acyl chloride groups undergo interfacial polymerization reaction at the interface between the aqueous phase and the oil phase.

[0050] In some specific embodiments, the mass concentration ratio of the diamine aqueous phase to the triacyl chloride oil phase can be 20:1 to 15:1, for example, 20:1, 19:1, 18:1, 17:1, 16:1 or 15:1. Optimizing the mass concentration ratio of the diamine aqueous phase solution and the triacyl chloride oil phase solution is beneficial to prevent a portion of the acyl chloride groups in the triacyl chloride from participating in the interfacial polymerization reaction, but hydrolyzing into carboxyl groups to achieve the grafting of amino alcohols. When the mass concentration ratio of the diamine aqueous phase to the triacyl chloride oil phase is too large, firstly, most of the acyl chlorides are used to participate in the interfacial polymerization reaction, and the acyl chlorides that can be hydrolyzed are reduced; secondly, the amount of acyl chlorides is reduced, the defects of the formed polyamide functional layer increase, the contact angle becomes larger, and the performance of the reverse osmosis membrane decreases (such as a significant decrease in the sodium chloride rejection rate).

[0051] In some specific embodiments, the mass concentration of the diamine aqueous phase is 2%-4%; the mass concentration of the triacyl chloride oil phase is 0.1%-0.2%.

[0052] In some specific embodiments, the mass concentration of the diamine aqueous phase may be 2%, 2.5%, 3%, 3.5% or 4%.

[0053] In some specific embodiments, the mass concentration of the triacyl chloride oil phase may be 0.1%, 0.15% or 0.2%.

[0054] In some specific embodiments, the drying includes: drying in the shade by means of air blowing.

[0055] In some embodiments, after the Schiff base is generated, the anti-pollution composite reverse osmosis membrane is heat treated and cleaned. The heat treatment further promotes the reaction and solidifies the polyamide layer, making the performance of the reverse osmosis membrane more stable.

[0056] In some specific embodiments, the heat treatment temperature may be 50° C.-70° C., such as 50° C., 55° C., 60° C., 65° C. or 70° C. The heat treatment time may be 5-30 min, such as 5 min, 10 min, 15 min, 20 min, 25 min or 30 min.

[0057] In some specific embodiments, the heat-treated membrane is cleaned with water.

[0058] The second aspect of the present invention provides an anti-pollution composite reverse osmosis membrane obtained by the preparation method of the first aspect of the present invention.

[0059] In some embodiments, the surface contact angle of the anti-fouling composite reverse osmosis membrane is less than 50°, preferably less than 40°.

[0060] In some embodiments, the base membrane comprises a polysulfone membrane.

[0061] The scheme of the present invention will be explained below in conjunction with the embodiments. It will be appreciated by those skilled in the art that the following embodiments are only used to illustrate the present invention and should not be considered as limiting the scope of the present invention. Where specific techniques or conditions are not indicated in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. The reagents or instruments used are not indicated by the manufacturer and are all conventional products that can be obtained commercially.

[0062] The reaction schemes of the following Examples 1-5 are as follows:

[0063]

[0064] Example 1

[0065] Prepare the water phase: dissolve the meta-phenylenediamine monomer in water, wherein the mass concentration of the meta-phenylenediamine is 3%.

[0066] Prepare the oil phase: dissolve trimesoyl chloride monomer in ethylcyclohexane, wherein the mass concentration of trimesoyl chloride is 0.15%.

[0067] Solution A was prepared by dissolving serinol and 4-dimethylaminopyridine in water, wherein the mass concentration of serinol was 0.5% and the mass concentration of 4-dimethylaminopyridine was 0.03%.

[0068] Preparation of solution B: dissolve glutaraldehyde and sodium dodecyl sulfate in water, wherein the mass concentration of glutaraldehyde is 5%, and the mass concentration of sodium dodecyl sulfate is 0.05%.

[0069] (1) pouring a water phase and an oil phase onto the surface of a polysulfone membrane in sequence, reacting at room temperature to generate a polyamide functional layer, and then drying in the shade by blowing air.

[0070] (2) Pour solution A onto the surface of the reverse osmosis membrane prepared in step (1), react at room temperature for 3 minutes, and then pour away the excess solution A on the surface.

[0071] (3) Pour solution B onto the surface of the reverse osmosis membrane prepared in step (2), react at room temperature for 3 minutes, pour off the excess solution B on the surface, place the membrane in a 60°C oven for heat treatment for 10 minutes, and finally soak the membrane in pure water for 24 hours for thorough pure water washing to obtain a reverse osmosis membrane with hydrophilic and antibacterial effects, and store the membrane in a 1000 ppm sodium bisulfite solution.

[0072] The surface contact angle of the prepared reverse osmosis membrane was measured to be 48.7°, indicating that the membrane had good hydrophilicity. The antibacterial rate of the prepared reverse osmosis membrane against Escherichia coli was measured to be above 91%.

[0073] Gram-negative Escherichia coli was selected and the antibacterial property of the composite membrane was evaluated by the bacterial liquid oscillation method.

[0074] Specifically, the frozen bacterial colony was cultured in a nutrient broth medium (5 g / L sodium chloride and beef extract, 10 g / L peptone, pH = 7.4-7.6), and then placed in a culture dish and cultured at 37°C for 24 hours to culture the first generation of bacteria. Then, 1 mL of the first generation of bacteria was placed in 100 mL of nutrient broth and cultured in a 37°C constant temperature shaker for 24 hours to produce the second generation of bacteria. The OD value of the second generation of bacteria was then measured with an ultraviolet spectrophotometer, and if it was greater than 0.5, it could be used for further operations.

[0075] 0.45 g of membrane sample was cut into 5 mm × 5 mm pieces and placed in a conical flask containing 42 mL PBS buffer (7.16 g / L sodium dihydrogen phosphate, 1.36 g / L potassium dihydrogen phosphate, 1000 mL deionized water) and 3 mL of the second generation bacterial dilution suspension. The blank control group was PBS without membrane bacterial suspension. In order to allow bacteria to fully contact with the membrane sample, the conical flask was shaken at 37 ° C for 24 h. Subsequently, 0.03 mL of bacterial suspension after contact with the membrane sample was diluted to different concentrations (10 0 ~10 9 ), and transfer 0.1 mL of bacterial solution of different concentrations to the plate. Three plates were used for each concentration for parallel experiments, and the plates were placed in an incubator at 37°C for 36 hours. Finally, the number of colonies on the agar plate was calculated using the plate count method, the concentration of the corresponding bacterial solution was calculated using formula (1), and the bacterial survival rate on each membrane sample was calculated using formula (2).

[0076] N=Z×R (1)

[0077] Where: N represents the bacterial concentration in the conical flask, CFU / mL; Z represents the average number of colonies on the membrane sample plate; R represents the dilution factor.

[0078] K=N m / N 0 (2)

[0079] Where: K represents bacterial survival rate, %; N m Indicates the bacterial solution concentration of the membrane sample, CFU / mL; N 0 Indicates the concentration of bacterial solution in the blank control group, CFU / mL.

[0080] Example 2

[0081] The anti-pollution composite reverse osmosis membrane was prepared according to the method of Example 1, except that the mass concentration of serinol in solution A was 0.7%, the mass concentration of 4-dimethylaminopyridine was 0.05%, and the mass concentration of glutaraldehyde in solution B was 8%.

[0082] The contact angle of the prepared reverse osmosis membrane surface was measured to be 42.5°, indicating that the membrane had good hydrophilicity. The antibacterial rate of the prepared reverse osmosis membrane against Escherichia coli was measured according to the method of Example 1, and it reached more than 93%.

[0083] Example 3

[0084] The anti-pollution composite reverse osmosis membrane was prepared according to the method of Example 1, except that the mass concentration of serinol in solution A was 0.9%, the mass concentration of 4-dimethylaminopyridine was 0.05%, and the mass concentration of glutaraldehyde in solution B was 10%.

[0085] The surface contact angle of the prepared reverse osmosis membrane was measured to be 38.7°, indicating that the membrane had good hydrophilicity. The antibacterial rate of the prepared reverse osmosis membrane against Escherichia coli was measured according to the method of Example 1, and it reached more than 96%.

[0086] Example 4

[0087] The anti-pollution composite reverse osmosis membrane was prepared according to the method of Example 1, except that the mass concentration of serinol in solution A was 1%, the mass concentration of 4-dimethylaminopyridine was 0.05%, and the mass concentration of glutaraldehyde in solution B was 10%.

[0088] The surface contact angle of the prepared reverse osmosis membrane was measured to be 34.6°, indicating that the membrane had good hydrophilicity. The antibacterial rate of the prepared reverse osmosis membrane against Escherichia coli was measured according to the method of Example 1, and it reached more than 96%.

[0089] Example 5

[0090] The anti-pollution composite reverse osmosis membrane was prepared according to the method of Example 1, except that the mass concentration of mesophenylenediamine in the aqueous phase was 4%, and the mass concentration of trimesoyl chloride in the oil phase was 0.1%.

[0091] The surface contact angle of the prepared reverse osmosis membrane was measured to be 62.4°. The antibacterial rate of the prepared reverse osmosis membrane against Escherichia coli was measured according to the method of Example 1 and reached 78%.

[0092] Example 6

[0093] An anti-pollution composite reverse osmosis membrane was prepared according to the method of Example 1, except that 2-amino-1,4-butanediol was used instead of serinol, and succinic dialdehyde was used instead of glutaraldehyde.

[0094] The surface contact angle of the prepared reverse osmosis membrane was measured to be 40.8°. The antibacterial rate of the prepared reverse osmosis membrane against Escherichia coli was measured according to the method of Example 1 and reached more than 94%.

[0095] Example 7

[0096] An anti-pollution composite reverse osmosis membrane was prepared according to the method of Example 4, except that the mass concentration of serinol in solution A was 1%, and the mass concentration of glutaraldehyde in solution B was 15%.

[0097] The surface contact angle of the prepared reverse osmosis membrane was measured to be 68.3°. The antibacterial rate of the prepared reverse osmosis membrane against Escherichia coli was measured according to the method of Example 1 and reached more than 82%.

[0098] Example 8

[0099] An anti-pollution composite reverse osmosis membrane was prepared according to the method of Example 4, except that the mass concentration of serinol in solution A was 1%, and the mass concentration of glutaraldehyde in solution B was 7%.

[0100] The surface contact angle of the prepared reverse osmosis membrane was measured to be 77.1°. The antibacterial rate of the prepared reverse osmosis membrane against Escherichia coli was measured according to the method of Example 1 and reached more than 74%.

[0101] Comparative Example 1

[0102] An anti-pollution composite reverse osmosis membrane was prepared according to the method of Example 1, except that step (2) and step (3) were not performed.

[0103] The surface contact angle of the prepared reverse osmosis membrane was measured to be 66.3°. The antibacterial rate of the prepared reverse osmosis membrane against Escherichia coli was measured according to the method of Example 1 and reached 8%.

[0104] Comparative Example 2

[0105] An anti-pollution composite reverse osmosis membrane was prepared according to the method of Example 1, except that step (3) was not performed.

[0106] The surface contact angle of the prepared reverse osmosis membrane was measured to be 45.3°, indicating that the membrane had good hydrophilicity. The antibacterial rate of the prepared reverse osmosis membrane against Escherichia coli was measured according to the method of Example 1, reaching 10%.

[0107] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0108] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for preparing an anti-pollution composite reverse osmosis membrane, characterized in that: The following steps are involved: Allowing a diamine aqueous phase and a triacyl chloride oil phase to undergo an interfacial polymerization reaction on the base film to form a polyamide layer, wherein the polyamide layer contains a carboxyl group; Under the action of a catalyst, the carboxyl group reacts with part of the hydroxyl groups in the amino alcohol, so that the amino alcohol is grafted onto the polyamide layer, wherein the amino alcohol contains at least 2 hydroxyl groups and at least 1 amino group; The amino groups in the amino alcohol grafted on the surface of the polyamide layer are reacted with polyaldehydes to generate Schiff bases, thereby obtaining the anti-pollution composite reverse osmosis membrane.

2. The preparation method according to claim 1, characterized in that: The amino alcohol containing at least two hydroxyl groups and at least one amino group includes one or more of serinol, 2-amino-1,4-butanediol, 3-amino-1,5-pentanediol, and 2-amino-1,5-pentanediol.

3. The preparation method according to claim 1 or 2, characterized in that: The polyaldehyde contains at least 2 aldehyde groups.

4. The preparation method according to claim 3, characterized in that: The polyaldehyde includes a long-chain polyaldehyde containing more than 4 carbon atoms; preferably, the polyaldehyde includes one or more of succindialdehyde, glutaraldehyde, adipaldehyde, and 3-methyl-glutaraldehyde.

5. The preparation method according to claim 1 or 2, characterized in that: The catalyst includes one or more of 4-dimethylaminopyridine, 4-pyrrolidinopyridine, and imidazole; The diamine includes one or more of m-phenylenediamine, p-phenylenediamine, and o-phenylenediamine; The triacid chloride includes trimesoyl chloride.

6. The preparation method according to claim 1 or 2, characterized in that: Grafting the amino alcohol comprises: dissolving the amino alcohol and a catalyst in a solvent, pouring the resulting solution on the surface of the polyamide layer, and removing the solution after the reaction; Preferably, the mass concentration of the amino alcohol is 0.5%-1%; Preferably, the mass concentration of the catalyst is 0.03%-0.05%.

7. The preparation method according to claim 1 or 2, characterized in that: Generating the Schiff base comprises: dissolving the polyaldehyde in a solvent, pouring the obtained solution on the surface of the grafted polyamide layer, and removing the solution after the reaction; Preferably, the polyaldehyde and the surfactant are dissolved together in a solvent; Preferably, the surfactant includes one or more of sodium dodecyl sulfate, sodium dodecyl sulfonate, and sodium dodecylbenzene sulfonate; Preferably, the mass concentration of the polyaldehyde is 5%-10%; Preferably, the mass concentration ratio of the polyaldehyde to the amino alcohol is 10:1-12:

1.

8. The preparation method according to claim 1 or 2, characterized in that: The preparation of the polyamide layer comprises: pouring the diamine aqueous phase and the triacyl chloride oil phase sequentially on the surface of the base film, and drying after the reaction; Preferably, the mass concentration ratio of the diamine aqueous phase to the triacyl chloride oil phase is 20:1 to 15:1; Preferably, the mass concentration of the diamine aqueous phase is 2%-4%; Preferably, the mass concentration of the triacyl chloride oil phase is 0.1%-0.2%.

9. The preparation method according to claim 1 or 2, characterized in that: After the Schiff base is generated, the anti-pollution composite reverse osmosis membrane is heat treated and cleaned; Preferably, the temperature of the heat treatment is 50°C-70°C.

10. An anti-pollution composite reverse osmosis membrane, characterized in that: The method is obtained by the preparation method according to any one of claims 1 to 9.

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