Reverse osmosis membranes, methods of making and using the same

Abstract

The application relates to the technical field of water treatment, in particular to a reverse osmosis membrane and a preparation method and application thereof. The preparation method of the reverse osmosis membrane comprises the following steps: contacting a base film with a water phase and an organic phase respectively, carrying out heat treatment to form a polyamide layer, and preparing the reverse osmosis membrane; the water phase comprises a multifunctional amine and an alkaline earth metal salt; and the organic phase comprises a multifunctional acyl halide, a phosphate ester and a compound containing a phosphoric anhydride bond. The reverse osmosis membrane prepared by the application has high membrane flux and high solute rejection rate, has excellent salt removal performance, and can meet the application requirements of high-temperature and high-salt water treatment.

Description

Technical Field

[0001] This application relates to the field of water treatment technology, and in particular to reverse osmosis membranes, their preparation methods, and applications. Background Technology

[0002] Reverse osmosis membranes are widely used in household water purifiers, industrial pure water production, wastewater treatment, and seawater desalination, making significant contributions to the sustainable use of water resources. Common composite polyamide membranes consist of a polyamide layer, a porous polysulfone support, and a polyester nonwoven fabric. The polyamide layer, due to its dense and highly cross-linked structure, endows the composite polyamide membrane with excellent selective separation capabilities, effectively allowing water molecules to pass through while efficiently retaining target solutes. The polyamide layer is generally prepared through interfacial polymerization, where monomers polymerize at the interface between immiscible aqueous and organic phases, generating a polyamide layer with a certain thickness and degree of cross-linking (see Cadotte's US4277344). Adding additives such as carboxylic acids to the aqueous or organic phase before polymerization can improve the membrane flux of the reverse osmosis membrane.

[0003] However, there is a trade-off between the membrane flux and solute rejection rate of reverse osmosis membranes, meaning that the two are inversely related. Traditional polyamide membranes can achieve high membrane flux, but they cannot improve the solute rejection rate while maintaining the membrane flux. This greatly limits the application of reverse osmosis membranes, especially in the field of high temperature and high saline treatment. Summary of the Invention

[0004] Therefore, the main objective of this application is to provide a method for preparing a reverse osmosis membrane that simultaneously has high flux and high solute rejection rate, in order to meet application requirements, especially in the field of high temperature and high saline treatment.

[0005] In a first aspect, this application provides a method for preparing a reverse osmosis membrane, comprising the following steps:

[0006] The reverse osmosis membrane is prepared by contacting the base membrane with the aqueous phase and the organic phase respectively and performing heat treatment to form a polyamide layer.

[0007] The aqueous phase includes polyfunctional amines and alkaline earth metal salts;

[0008] The organic phase includes polyfunctional acyl halides, phosphate esters, and compounds containing phosphoric anhydride bonds.

[0009] In some embodiments, the polyfunctional amine includes one or more of the following: aromatic compounds having at least two active amino groups, aliphatic compounds having at least two active amino groups, and alicyclic compounds having at least two active amino groups.

[0010] Optionally, the polyfunctional amine includes one or more of m-phenylenediamine, pyromellitic diamine, 1,3,5-triaminobenzene, 1,2,4-triaminobenzene, 3,5-diaminobenzoic acid, 2,4-diaminotoluene, 2,6-diaminotoluene, 2,4-diaminoanisole, amiodol, xylenediamine, ethylenediamine, propylenediamine, tris(2-aminoethyl)amine, 1,3-diaminocyclohexane, 1,2-diaminocyclohexane, 1,4-diaminocyclohexane, piperazine, 2,5-dimethylpiperazine, and 4-aminomethylpiperazine; further optionally, it includes m-phenylenediamine.

[0011] In some embodiments, the alkaline earth metal salt includes one or more of calcium salts, magnesium salts, and barium salts;

[0012] Optionally, the alkaline earth metal salt includes one or more of calcium chloride, calcium nitrate, calcium gluconate, magnesium chloride, magnesium sulfate, magnesium nitrate, barium chloride, and barium nitrate, and may further include calcium chloride.

[0013] In some embodiments, the polyfunctional acyl halide includes polyfunctional acyl chloride;

[0014] Optionally, the multifunctional acyl chloride includes one or more of the following: aromatic acyl chloride having at least two acyl chloride groups, aliphatic acyl chloride having at least two acyl chloride groups, and alicyclic acyl chloride having at least two acyl chloride groups;

[0015] Further optionally, the polyfunctional acyl chloride includes one or more of the following: trimesoyl chloride, terephthaloyl chloride, isophthaloyl chloride, biphenyl dicarboxylate chloride, naphthalene dicarboxylic acid dichloride, benzene trisulfonyl chloride, benzene disulfonyl chloride, monochlorosulfonylbenzene dicarboxylate chloride, propane tricarboxylate chloride, butane tricarboxylate chloride, pentane tricarboxylate chloride, glutaryl halide, adipyl halide, cyclopropane tricarboxylate chloride, cyclobutane tetracarboxylate chloride, cyclopentane tricarboxylate chloride, cyclopentane tetracarboxylate chloride, cyclohexane tricarboxylate chloride, tetrahydrofuran tetracarboxylate chloride, cyclopentane dicarboxylate chloride, cyclobutane dicarboxylate chloride, cyclohexane dicarboxylate chloride, and tetrahydrofuran dicarboxylate chloride; and even more preferably, trimesoyl chloride.

[0016] In some embodiments, the phosphate ester includes one or more of triethyl phosphate, tributyl phosphate, tri(2-ethylhexyl) phosphate, triphenyl phosphate, and tri(1,3-dichloro-2-propyl) phosphate, optionally including tributyl phosphate.

[0017] In some embodiments, the compound containing a phosphoric anhydride bond includes one or more of adenosine diphosphate, adenosine triphosphate, pyrophosphate, n-propylphosphonic anhydride, and ethyl methylphosphonic anhydride, optionally including pyrophosphate.

[0018] In some embodiments, one or more of the following features are satisfied:

[0019] (1) In the aqueous phase, the mass percentage of polyfunctional amines is 1.5wt%~5.0wt%;

[0020] (2) In the aqueous phase, the mass percentage of alkaline earth metal salt is 0.1wt%~5.0wt%, and can be selected as 0.5wt%~2.0wt%;

[0021] (3) In the organic phase, the mass percentage of polyfunctional acyl halides is 0.1wt%~0.4wt%;

[0022] (4) In the organic phase, the mass percentage of phosphate ester is 0.02wt%~0.7wt%;

[0023] (5) In the organic phase, the mass percentage of the compound containing phosphoric anhydride bonds is 0.001wt%~0.03wt%.

[0024] In some embodiments, one or more of the following features are satisfied:

[0025] (1) The solvent of the organic phase includes organic solvents;

[0026] Optionally, the organic solvent includes aliphatic hydrocarbon solvents;

[0027] Optionally, the aliphatic hydrocarbon solvent includes one or more of isoalkanes, n-hexane, and n-decane, and may further include Isopar-G;

[0028] (2) The base film includes a nonwoven fabric and a porous carrier layer, wherein the base film includes a nonwoven fabric and a porous carrier layer, and the porous carrier layer includes a polymer;

[0029] Optionally, the polymer includes polysulfone, polyethersulfone, polyimide, polyamide, polyetherimide, polyacrylonitrile, polyethylene, polypropylene, and halogen-containing polymers;

[0030] Optionally, the halogenated polymer includes polyvinylidene fluoride;

[0031] Optionally, the base film comprises a nonwoven fabric and a polysulfone layer laminated on the surface of the nonwoven fabric;

[0032] (3) The steps of contacting the base membrane with the aqueous phase and the organic phase respectively include: contacting the base membrane with the aqueous phase for a first time, and then contacting it with the organic phase for a second time;

[0033] Optionally, the first time and the second time are each independent and range from 10s to 60s;

[0034] (4) The conditions for the heat treatment include: treatment time of 1 min to 10 min; treatment temperature of 50℃ to 90℃.

[0035] Secondly, this application provides a reverse osmosis membrane prepared by the preparation method described in the first aspect;

[0036] Optionally, the reverse osmosis membrane achieves a desalination rate of ≥99.8% under the test conditions of 2000ppm NaCl, 25℃, pH 7~8, and 1.55MPa.

[0037] Optionally, the reverse osmosis membrane achieves a desalination rate of ≥99.4% under test conditions of 10000ppm NaCl, 35℃, pH 7~8, and 1.55MPa.

[0038] Optionally, the reverse osmosis membrane achieves a desalination rate of ≥99% under test conditions of 10000ppm NaCl, 35℃, pH 7~8, 1.55MPa, and 15% recovery rate.

[0039] Thirdly, this application provides the application of the reverse osmosis membrane prepared by the preparation method described in the first aspect or the reverse osmosis membrane described in the second aspect in water treatment;

[0040] Optionally, the water treatment conditions include one or more of the following characteristics:

[0041] (1) The processing temperature is ≥5℃, and can be selected as 30℃~35℃;

[0042] (2) The salt content of the treated water is ≥100ppm, and can be selected as 4000ppm~20000ppm.

[0043] Studies have found that there is a trade-off relationship between the membrane flux and solute rejection rate of reverse osmosis membranes, meaning that the two are mutually exclusive. Therefore, traditional polyamide membranes cannot simultaneously improve both membrane flux and solute rejection rate, which greatly limits the application of reverse osmosis membranes, especially in the field of high temperature and high saline treatment.

[0044] This application utilizes an aqueous phase containing polyfunctional amines and alkaline earth metal salts to form a polyamide layer through interfacial polymerization on a base membrane (such as a porous polysulfone membrane). The reaction involves the interaction of an aqueous phase containing polyfunctional amines and alkaline earth metal salts with an organic phase containing polyfunctional acyl halides, phosphate esters, and compounds with phosphoric anhydride bonds. Phosphate esters associate with polyfunctional acyl halides, resulting in a more uniform reaction between the monomers and amines at the interface. This improves the thickness and structural uniformity of the polyamide layer, although the degree of crosslinking is slightly lower. Alkaline earth metal salts, through precipitation reactions with compounds containing phosphoric anhydride bonds, construct ion channels at the oil-water interface. This facilitates the diffusion of multifunctional amines through the primary polyamide layer into the organic phase, thereby enhancing the crosslinking reaction with polyfunctional acyl halides and increasing the degree of crosslinking in the polyamide layer. This process yields a reverse osmosis membrane with increased thickness, higher crosslinking degree, and structural uniformity. This reverse osmosis membrane exhibits both high membrane flux and high solute rejection rate, demonstrating excellent salt removal performance and meeting the application requirements for high-temperature and high-salt water treatment. Detailed Implementation

[0045] The method for preparing alkynyl alcohols by ketethynylation of this application is further described in detail below with reference to specific embodiments. This application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in this application and in its specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0047] In this application, "one or more" means any one, two or more of the listed items.

[0048] In this application, terms such as "first aspect," "second aspect," "third aspect," and "fourth aspect" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, terms such as "first," "second," "third," and "fourth" serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on quantity.

[0049] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0050] In this application, numerical ranges are involved. Unless otherwise specified, the numerical ranges mentioned above are considered continuous and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. In addition, when multiple ranges are provided to describe features or characteristics, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed in this application should be understood to include any and all subranges to which they are included.

[0051] Unless otherwise specified, the percentage content mentioned in this application refers to mass percentage for solid-liquid mixtures and liquid-liquid mixtures, and volume (molar) percentage for gas-gas mixtures.

[0052] Unless otherwise specified, all percentage concentrations mentioned in this application refer to the final concentration. The final concentration refers to the proportion of the added component in the system after the addition of that component.

[0053] Unless otherwise specified, the temperature parameters in this application may be either constant temperature processing or processing within a certain temperature range. The constant temperature processing allows for temperature fluctuations within the precision range controlled by the instrument.

[0054] In this application, room temperature generally refers to 4℃-30℃, and preferably 20±5℃.

[0055] In a first aspect, this application provides a method for preparing a reverse osmosis membrane, comprising the following steps:

[0056] The reverse osmosis membrane is prepared by contacting the base membrane with the aqueous phase and the organic phase respectively and performing heat treatment to form a polyamide layer.

[0057] The aqueous phase includes polyfunctional amines and alkaline earth metal salts;

[0058] The organic phase includes polyfunctional acyl halides, phosphate esters, and compounds containing phosphoric anhydride bonds.

[0059] This application utilizes an aqueous phase containing polyfunctional amines and alkaline earth metal salts to form a polyamide layer through interfacial polymerization on a base membrane (such as a porous polysulfone membrane). The reaction involves the interaction of an aqueous phase containing polyfunctional amines and alkaline earth metal salts with an organic phase containing polyfunctional acyl halides, phosphate esters, and compounds with phosphoric anhydride bonds. Phosphate esters associate with polyfunctional acyl halides, resulting in a more uniform reaction between the monomers and amines at the interface. This improves the thickness and structural uniformity of the polyamide layer, although the degree of crosslinking is slightly lower. Alkaline earth metal salts, through precipitation reactions with compounds containing phosphoric anhydride bonds, construct ion channels at the oil-water interface. This facilitates the diffusion of multifunctional amines through the primary polyamide layer into the organic phase, thereby enhancing the crosslinking reaction with polyfunctional acyl halides and increasing the degree of crosslinking in the polyamide layer. This process yields a reverse osmosis membrane with increased thickness, higher crosslinking degree, and structural uniformity. This reverse osmosis membrane exhibits both high membrane flux and high solute rejection rate, demonstrating excellent salt removal performance and meeting the application requirements for high-temperature and high-salt water treatment. Understandably, during the preparation of polyamide layers, the amino group in the polyfunctional amine and the acyl halide in the polyfunctional acyl halide are usually reacted in a molar ratio of 1:(0.95~1.05), for example, 1:1.

[0060] In some embodiments, the polyfunctional amine includes one or more of the following: aromatic compounds having at least two active amino groups, aliphatic compounds having at least two active amino groups, and alicyclic compounds having at least two active amino groups.

[0061] Optionally, the polyfunctional amine includes one or more of m-phenylenediamine, pyromellitic diamine, 1,3,5-triaminobenzene, 1,2,4-triaminobenzene, 3,5-diaminobenzoic acid, 2,4-diaminotoluene, 2,6-diaminotoluene, 2,4-diaminoanisole, amiodol, xylenediamine, ethylenediamine, propylenediamine, tris(2-aminoethyl)amine, 1,3-diaminocyclohexane, 1,2-diaminocyclohexane, 1,4-diaminocyclohexane, piperazine, 2,5-dimethylpiperazine, and 4-aminomethylpiperazine; further optionally, it includes m-phenylenediamine.

[0062] In some embodiments, the alkaline earth metal salt includes one or more of calcium salts, magnesium salts, and barium salts;

[0063] Optionally, the alkaline earth metal salt includes one or more of calcium chloride, calcium nitrate, calcium gluconate, magnesium chloride, magnesium sulfate, magnesium nitrate, barium chloride, and barium nitrate, and may further include calcium chloride.

[0064] In some embodiments, the polyfunctional acyl halide includes polyfunctional acyl chloride;

[0065] Optionally, the multifunctional acyl chloride includes one or more of the following: aromatic acyl chloride having at least two acyl chloride groups, aliphatic acyl chloride having at least two acyl chloride groups, and alicyclic acyl chloride having at least two acyl chloride groups;

[0066] Further optionally, the polyfunctional acyl chloride includes one or more of the following: trimesoyl chloride, terephthaloyl chloride, isophthaloyl chloride, biphenyl dicarboxylate chloride, naphthalene dicarboxylic acid dichloride, benzene trisulfonyl chloride, benzene disulfonyl chloride, monochlorosulfonylbenzene dicarboxylate chloride, propane tricarboxylate chloride, butane tricarboxylate chloride, pentane tricarboxylate chloride, glutaryl halide, adipyl halide, cyclopropane tricarboxylate chloride, cyclobutane tetracarboxylate chloride, cyclopentane tricarboxylate chloride, cyclopentane tetracarboxylate chloride, cyclohexane tricarboxylate chloride, tetrahydrofuran tetracarboxylate chloride, cyclopentane dicarboxylate chloride, cyclobutane dicarboxylate chloride, cyclohexane dicarboxylate chloride, and tetrahydrofuran dicarboxylate chloride; and even more preferably, trimesoyl chloride.

[0067] In some embodiments, the phosphate ester includes one or more of triethyl phosphate, tributyl phosphate, tri(2-ethylhexyl) phosphate, triphenyl phosphate, and tri(1,3-dichloro-2-propyl) phosphate, optionally including tributyl phosphate.

[0068] In some embodiments, the compound containing a phosphoric anhydride bond includes one or more of adenosine diphosphate, adenosine triphosphate, pyrophosphate, n-propylphosphonic anhydride, and ethyl methylphosphonic anhydride, optionally including pyrophosphate.

[0069] In some embodiments, one or more of the following features are satisfied:

[0070] (1) In the aqueous phase, the mass percentage of the polyfunctional amine is 1.5wt% to 5.0wt%, for example, 1.5wt%, 2wt%, 3wt%, 4wt%, 5.0wt%, etc.;

[0071] (2) In the aqueous phase, the mass percentage of alkaline earth metal salt is 0.1wt%~5.0wt%, which can be selected as 0.5wt%~2.0wt%, for example 0.1wt%, 0.5wt%, 1wt%, 2wt%, 3wt%, 4wt%, 5.0wt%, etc.;

[0072] (3) In the organic phase, the mass percentage of the polyfunctional acyl halide is 0.1wt%~0.4wt%, for example 0.1wt%, 0.2wt%, 0.3wt%, 0.4wt%, etc.;

[0073] (4) In the organic phase, the mass percentage of phosphate ester is 0.02wt%~0.7wt%, for example 0.02wt%, 0.05wt%, 0.1wt%, 0.3wt%, 0.5wt%, 0.7wt%, etc.;

[0074] (5) In the organic phase, the mass percentage of the compound containing phosphoric anhydride bond is 0.001wt% to 0.03wt%, for example, 0.001wt%, 0.005wt%, 0.01wt%, 0.02wt%, 0.03wt%, etc.

[0075] In some embodiments, one or more of the following features are satisfied:

[0076] (1) The solvent of the organic phase includes organic solvents;

[0077] Optionally, the organic solvent includes aliphatic hydrocarbon solvents;

[0078] Optionally, the aliphatic hydrocarbon solvent includes one or more of isoalkanes, n-hexane, and n-decane, and may further include Isopar-G;

[0079] (2) The base film includes a nonwoven fabric and a porous carrier layer, wherein the base film includes a nonwoven fabric and a porous carrier layer, and the porous carrier layer includes a polymer;

[0080] Optionally, the polymer includes polysulfone, polyethersulfone, polyimide, polyamide, polyetherimide, polyacrylonitrile, polyethylene, polypropylene, and halogen-containing polymers;

[0081] Optionally, the halogenated polymer includes polyvinylidene fluoride;

[0082] Optionally, the base film comprises a nonwoven fabric and a polysulfone layer laminated on the surface of the nonwoven fabric;

[0083] (3) The steps of contacting the base membrane with the aqueous phase and the organic phase respectively include: contacting the base membrane with the aqueous phase for a first time, and then contacting it with the organic phase for a second time;

[0084] Optionally, the first time and the second time are each independent and range from 10s to 60s, for example, 10s, 20s, 30s, 40s, 50s, 60s, etc.

[0085] (4) The conditions for heat treatment include: treatment time of 1 min to 10 min, such as 1 min, 3 min, 5 min, 7 min, 9 min, 10 min, etc.; and treatment temperature of 50℃ to 90℃, such as 50℃, 60℃, 70℃, 80℃, 90℃, etc.

[0086] Secondly, this application provides a reverse osmosis membrane prepared by the preparation method described in the first aspect;

[0087] Optionally, the reverse osmosis membrane achieves a desalination rate of ≥99.8% under the test conditions of 2000ppm NaCl, 25℃, pH 7~8, and 1.55MPa.

[0088] Optionally, the reverse osmosis membrane achieves a desalination rate of ≥99.4% under test conditions of 10000ppm NaCl, 35℃, pH 7~8, and 1.55MPa.

[0089] Optionally, the reverse osmosis membrane achieves a desalination rate of ≥99% under test conditions of 10000ppm NaCl, 35℃, pH 7~8, 1.55MPa, and 15% recovery rate.

[0090] Understandably, the testing conditions differ depending on the application of the reverse osmosis membrane. For reverse osmosis membrane sheets, the recovery rate does not need to be considered, while for reverse osmosis membrane elements, the recovery rate can be considered.

[0091] Thirdly, this application provides the application of the reverse osmosis membrane prepared by the preparation method described in the first aspect or the reverse osmosis membrane described in the second aspect in water treatment;

[0092] Optionally, the water treatment conditions include one or more of the following characteristics:

[0093] (1) The processing temperature is ≥5℃, and can be selected as 30℃~35℃, such as 5℃, 10℃, 15℃, 20℃, 30℃, 35℃, etc.;

[0094] (2) The salt content of the treated water is ≥100ppm, and can be selected from 4000ppm to 20000ppm, such as 100ppm, 500ppm, 1000ppm, 2000ppm, 4000ppm, 10000ppm, 15000ppm, 20000ppm, etc.

[0095] The technical solution of this application will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely to help understand this application and should not be regarded as specific limitations on this application.

[0096] 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 Table 1 below.

[0097] Table 1 Raw Materials

[0098]

[0099] Performance testing methods:

[0100] 1. Evaluation of the basic separation performance of reverse osmosis membrane sheets

[0101] Desalination rate and permeate flux are two important parameters for evaluating the basic separation performance of reverse osmosis membranes. This application evaluates the separation performance of reverse osmosis membranes according to GB / T 32373-2015 "Test Methods for Reverse Osmosis Membranes".

[0102] The desalination rate (R) is defined as the difference between the feed solution salt concentration (Cf) and the permeate salt concentration (Cp) under certain operating conditions, divided by the feed solution salt concentration (Cf), as shown in equation (1).

[0103] Equation (1)

[0104] Permeation flux is defined as the volume of water that permeates through a unit membrane area per unit time under certain operating conditions, and its unit is L / (m²). 2 ·h).

[0105] The operating conditions used for the reverse osmosis membrane performance test in this application are as follows: the feed solution is a 2000 ppm sodium chloride aqueous solution, the solution pH is 7.5±0.5, the operating pressure is 1.55 MPa, and the operating temperature is 25℃.

[0106] 2. Evaluation of high-temperature and high-salt membrane separation performance

[0107] 2.1 Evaluation of the high-salt separation performance of reverse osmosis membrane sheets

[0108] The operating conditions are as follows: the feed solution is a 10,000 ppm sodium chloride aqueous solution, the solution pH is 7.5 ± 0.5, the operating pressure is 1.55 MPa, and the operating temperature is 25℃.

[0109] 2.2 Evaluation of the high-temperature and high-salt separation performance of reverse osmosis elements

[0110] The operating conditions were as follows: the feed solution was a 10,000 ppm sodium chloride aqueous solution, the pH was 7.5 ± 0.5, the operating pressure was 1.55 MPa, the operating temperature was 35℃, and the recovery rate was 15%.

[0111] Example 1

[0112] Preparation of polysulfone-based films:

[0113] Prepare 250g of polysulfone casting solution containing 16.3 wt% polysulfone resin in N,N-dimethylformamide; coat the filtered and degassed polysulfone casting solution onto a polyester nonwoven fabric with a coating thickness controlled at 150 μm; immerse in water to form a membrane through phase inversion, and then clean to obtain a polysulfone-based membrane.

[0114] Preparation of reverse osmosis membrane:

[0115] S1: Dissolve 4g of m-phenylenediamine in 94g of water, then add 1.5g of calcium chloride to prepare an aqueous phase containing 4.0wt% m-phenylenediamine and 1.5wt% calcium chloride;

[0116] S2: Dissolve 0.15g of pyromellitic chloride in 99.81g of Isopar G isoalkanes, then add 0.04g of tributyl phosphate and 0.005g of pyrophosphate to prepare an organic phase containing 0.15wt% pyromellitic chloride, 0.04wt% tributyl phosphate and 0.005wt% pyrophosphate;

[0117] S3: The polysulfone-based membrane is contacted with the aqueous phase and the organic phase for 30 seconds, and then heat-treated at 70°C for 3 minutes to obtain the reverse osmosis membrane.

[0118] Examples 2-9

[0119] The reverse osmosis membranes of Example 1 were prepared using the same method as in Example 1, with the only difference being the type of raw materials, the amount of raw materials added, or the process parameters. See Table 2 for details.

[0120] Comparative Example 1

[0121] Compared with Example 1, the only difference is that the aqueous phase does not contain calcium chloride, and the organic phase does not contain tributyl phosphate and pyrophosphate.

[0122] Comparative Example 2

[0123] Compared with Example 1, the only difference is that the organic phase does not contain tributyl phosphate.

[0124] Comparative Example 3

[0125] Compared with Example 1, the only difference is that the aqueous phase does not contain calcium chloride and the organic phase does not contain pyrophosphate.

[0126] The basic separation performance of the reverse osmosis membranes obtained in different embodiments and comparative examples was evaluated, as well as the separation performance of the membranes and reverse osmosis elements under high temperature and high salt conditions. The results are listed in Table 3.

[0127] Table 2. Components and process conditions of the examples and comparative examples

[0128]

[0129] Table 3 Evaluation results of the examples and comparative examples

[0130]

[0131] As shown in Table 3, the reverse osmosis membrane prepared in this application possesses both high water flux and excellent desalination performance, maintaining a high desalination rate under high temperature and high salinity conditions. Comparing Example 1 and Comparative Examples 1-3, it can be seen that, compared to Comparative Example 1, Comparative Example 2, by adding only an alkaline earth metal salt to the aqueous phase and a compound containing a phosphoric anhydride bond to the organic phase, improved the desalination rate but did not significantly improve the flux. Comparative Example 3, compared to Comparative Example 1, only added a phosphate ester to the organic phase, which improved the membrane flux but also significantly degraded the desalination effect. Example 1, compared to Comparative Example 1, improved both membrane flux and desalination performance simultaneously. Therefore, the reverse osmosis membrane prepared by adding an alkaline earth metal salt to the aqueous phase and a phosphate ester and a compound containing a phosphoric anhydride bond to the organic phase possesses both high membrane flux and high solute rejection rate, exhibiting excellent salt removal performance and meeting the application requirements for high temperature and high salinity treatment.

[0132] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0133] The embodiments described above are merely illustrative of several implementation methods of this application, intended to facilitate a detailed understanding of the technical solutions of this application, but should not be construed as limiting the scope of protection of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the scope of protection of this application. It should be understood that technical solutions obtained by those skilled in the art based on the technical solutions provided in this application through logical analysis, reasoning, or limited experimentation are all within the scope of protection of the appended claims. Therefore, the scope of protection of this patent application should be determined by the content of the appended claims, and the specification can be used to interpret the content of the claims.

Claims

1. A method for preparing a reverse osmosis membrane, characterized in that, The steps include the following: The reverse osmosis membrane is prepared by contacting the base membrane with the aqueous phase and the organic phase respectively and performing heat treatment to form a polyamide layer. The aqueous phase includes polyfunctional amines and alkaline earth metal salts; The organic phase includes polyfunctional acyl halides, phosphate esters, and compounds containing phosphoric anhydride bonds.

2. The preparation method according to claim 1, characterized in that, The polyfunctional amines include one or more of the following: aromatic compounds having at least two active amino groups, aliphatic compounds having at least two active amino groups, and alicyclic compounds having at least two active amino groups.

3. The preparation method according to claim 2, characterized in that, The polyfunctional amines include one or more of the following: m-phenylenediamine, 1,3,5-triaminobenzene, 1,2,4-triaminobenzene, 3,5-diaminobenzoic acid, 2,4-diaminotoluene, 2,6-diaminotoluene, amiodarone, xylenediamine, ethylenediamine, propylenediamine, tris(2-aminoethyl)amine, 1,3-diaminocyclohexane, 1,2-diaminocyclohexane, 1,4-diaminocyclohexane, piperazine, 2,5-dimethylpiperazine, and 4-aminomethylpiperazine.

4. The preparation method according to claim 3, characterized in that, The polyfunctional amines include m-phenylenediamine.

5. The preparation method according to claim 1, characterized in that, The alkaline earth metal salts include one or more of calcium, magnesium, and barium salts.

6. The preparation method according to claim 5, characterized in that, The alkaline earth metal salts include one or more of calcium chloride, calcium nitrate, calcium gluconate, magnesium chloride, magnesium sulfate, magnesium nitrate, barium chloride, and barium nitrate.

7. The preparation method according to claim 6, characterized in that, The alkaline earth metal salts include calcium chloride.

8. The preparation method according to claim 1, characterized in that, The polyfunctional acyl halides include polyfunctional acyl chlorides.

9. The preparation method according to claim 8, characterized in that, The multifunctional acyl chlorides include one or more of aromatic acyl chlorides having at least two acyl chloride groups, aliphatic acyl chlorides having at least two acyl chloride groups, and alicyclic acyl chlorides having at least two acyl chloride groups.

10. The preparation method according to claim 9, characterized in that, The polyfunctional acyl chlorides include one or more of the following: pyromellitic acyl chloride, terephthaloyl chloride, isophthaloyl chloride, biphenyl dicarboxylic acid acyl chloride, naphthalene dicarboxylic acid dichloride, benzene trisulfonyl chloride, benzene disulfonyl chloride, glutaryl halide, adipicoyl halide, cyclobutane dicarboxylic acid acyl chloride, and cyclohexane dicarboxylic acid acyl chloride.

11. The preparation method according to claim 10, characterized in that, The polyfunctional acyl chlorides include pyromellitic acid chloride.

12. The preparation method according to claim 1, characterized in that, The phosphate esters include one or more of triethyl phosphate, tributyl phosphate, tri(2-ethylhexyl) phosphate, triphenyl phosphate, and tri(1,3-dichloro-2-propyl) phosphate.

13. The preparation method according to claim 12, characterized in that, The phosphate esters include tributyl phosphate.

14. The preparation method according to claim 1, characterized in that, The compounds containing phosphoric anhydride bonds include one or more of adenosine diphosphate, adenosine triphosphate, pyrophosphate, n-propylphosphonic anhydride, and ethylmethylphosphonic anhydride.

15. The preparation method according to claim 14, characterized in that, The compounds containing phosphoric anhydride bonds include pyrophosphate.

16. The preparation method according to any one of claims 1-15, characterized in that, It meets one or more of the following characteristics: (1) In the aqueous phase, the mass percentage of polyfunctional amines is 1.5wt%~5.0wt%; (2) The mass percentage of alkaline earth metal salt in the aqueous phase is 0.1wt%~5.0wt%; (3) In the organic phase, the mass percentage of polyfunctional acyl halides is 0.1wt%~0.4wt%; (4) In the organic phase, the mass percentage of phosphate ester is 0.02wt%~0.7wt%; (5) In the organic phase, the mass percentage of the compound containing phosphoric anhydride bonds is 0.001wt%~0.03wt%.

17. The preparation method according to claim 16, characterized in that, In the aqueous phase, the mass percentage of alkaline earth metal salt is 0.5wt% to 2.0wt%.

18. The preparation method according to any one of claims 1-15, characterized in that, It meets one or more of the following characteristics: (1) The solvent of the organic phase includes organic solvents; (2) The base film includes a nonwoven fabric and a porous carrier layer, wherein the porous carrier layer includes a polymer; (3) The steps of contacting the base membrane with the aqueous phase and the organic phase respectively include: contacting the base membrane with the aqueous phase for a first time, and then contacting it with the organic phase for a second time; (4) The conditions for the heat treatment include: treatment time of 1 min to 10 min; treatment temperature of 50℃ to 90℃.

19. The preparation method according to claim 18, characterized in that, The organic solvents include aliphatic hydrocarbon solvents.

20. The preparation method according to claim 19, characterized in that, The aliphatic hydrocarbon solvent includes one or more of isoalkanes, n-hexane, and n-decane.

21. The preparation method according to claim 20, characterized in that, The aliphatic hydrocarbon solvents include Isopar-G.

22. The preparation method according to claim 18, characterized in that, The polymers include polysulfone, polyethersulfone, polyimide, polyamide, polyetherimide, polyacrylonitrile, polyethylene, polypropylene, or halogen-containing polymers.

23. The preparation method according to claim 22, characterized in that, The halogenated polymer includes polyvinylidene fluoride.

24. The preparation method according to claim 22, characterized in that, The base film comprises a nonwoven fabric and a polysulfone layer laminated on the surface of the nonwoven fabric.

25. The preparation method according to claim 18, characterized in that, The first and second times are independent and range from 10s to 60s.

26. A reverse osmosis membrane prepared by the preparation method according to any one of claims 1-25.

27. The reverse osmosis membrane as described in claim 26, characterized in that, The reverse osmosis membrane achieved a desalination rate of ≥99.8% under test conditions of 2000ppm NaCl, 25℃, pH 7~8, and 1.55MPa.

28. The reverse osmosis membrane as described in claim 26, characterized in that, The reverse osmosis membrane achieved a desalination rate of ≥99.4% under test conditions of 10000ppm NaCl, 35℃, pH 7~8, and 1.55MPa.

29. The reverse osmosis membrane as described in claim 26, characterized in that, The reverse osmosis membrane achieved a desalination rate of ≥99% under the test conditions of 10000ppm NaCl, 35℃, pH 7~8, 1.55MPa, and 15% recovery rate.

30. The application of the reverse osmosis membrane prepared by the preparation method according to any one of claims 1-25, and the reverse osmosis membrane according to any one of claims 26-29, in water treatment.

31. The application as described in claim 30, characterized in that, The conditions for water treatment include one or more of the following characteristics: (1) Processing temperature ≥ 5℃; (2) The salt content of the treated water is ≥100ppm.

32. The application as described in claim 31, characterized in that, The processing temperature is 30℃~35℃.

33. The application as described in claim 31, characterized in that, The salt content of the treated water is 4000ppm to 20000ppm.

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