Method for producing a seawater desalination reverse osmosis membrane and a reverse osmosis membrane produced thereby

Abstract

The present application relates to a method for preparing a seawater desalination reverse osmosis membrane and a reverse osmosis membrane prepared thereby. The method comprises: preparing a base membrane, the base membrane comprising a support material and a polymer porous support layer formed on the support material, the polymer porous support layer being formed from a casting solution, the casting solution comprising a polymer and a solvent; contacting the base membrane with an aqueous phase solution comprising an amine monomer; then contacting with an organic phase solution comprising an acyl chloride monomer having two or more acyl chloride groups, a flux-enhancing complexing agent and an organic solvent, the flux-enhancing complexing agent being composed of a co-solvent and a plasticizer; contacting with an ethanol solution comprising an acyl chloride monomer having one to two acyl chloride groups; washing; treating with an aqueous solution comprising glycerol and tea polyphenol; and drying. The seawater desalination reverse osmosis membrane prepared by the method can simultaneously achieve excellent desalination rate and boron removal rate and flux, and remains stable in performance during long-term storage in the form of a dry membrane.

Description

Technical Field

[0001] This invention relates to a method for preparing a seawater desalination reverse osmosis membrane and the reverse osmosis membrane prepared therefrom, and more specifically to the field of seawater desalination reverse osmosis membranes that simultaneously achieve excellent desalination rate, deboronization rate, and flux while maintaining stable performance during long-term storage. Background Technology

[0002] The main technologies for seawater desalination currently include reverse osmosis, distillation, and electrodialysis. Among them, reverse osmosis is considered a reliable method with low energy consumption.

[0003] In practical applications, the quality requirements for the produced water are becoming increasingly stringent. The boron content in seawater is mainly in the range of 4-7 mg / L. Boron is one of the essential trace elements for biological life activities, but excessive intake can lead to a series of diseases in the human body.

[0004] The World Health Organization (WHO) currently sets the safe drinking water standard for boron at less than 0.5 ppm per liter of water. When seawater has a pH less than 8, boron mainly exists in the water as non-charged boric acid with a very small molecular weight. In most cases, it can only be removed by sieving. However, even after separation by a primary seawater desalination reverse osmosis system, the boron content in the product water is still as high as 0.8~1.5 mg / L, and the removal rate is still relatively low, requiring further treatment.

[0005] Furthermore, in the current process of preparing seawater desalination reverse osmosis membranes, it is necessary to clean the membrane to reduce the residual reactive monomers, such as m-phenylenediamine. Excessive residue can lead to changes in the molecular structure of the membrane during long-term storage, resulting in phenomena such as yellowing of the membrane surface. At this time, the membrane performance will also decrease to varying degrees. Therefore, the storage of seawater desalination reverse osmosis membranes usually requires a specific environment, but it is still impossible to completely avoid performance degradation caused by storage. Therefore, it is crucial to prepare membranes that are more stable for storage.

[0006] Currently, many scholars have participated in the research on seawater desalination reverse osmosis membranes and have made certain improvements to their boron removal performance.

[0007] Patent document CN117654302A provides a boron-removing seawater desalination reverse osmosis membrane with functionalized graphene and its preparation method. Functionalized graphene / graphene oxide is introduced into the polyamide separation layer of the reverse osmosis membrane through interfacial polymerization. The special pore structure and interlayer structure of the functionalized graphene / graphene oxide are utilized to improve the permeation and separation performance of the reverse osmosis membrane, thereby achieving a simultaneous increase in the boron removal rate and water flux of the reverse osmosis membrane.

[0008] However, the reverse osmosis membranes prepared in this patent document all have a flux of less than 3 for pure water. ( The abbreviation is LMH (1 GFD = 1.698 LMH). The flux for simulated seawater (320.00 g NaCl / 10 L) is less than 1 LMH, the desalination rate for simulated seawater is less than 99.17%, and the boron removal rate for simulated seawater (boron concentration of 5 mg / L) is less than 86.03%.

[0009] Patent document CN117732247A provides a boron-removing reverse osmosis membrane and its preparation method and application. It mentions that after forming a polyamide layer through interfacial polymerization, an allyl compound containing an amino group is used for post-treatment, thereby forming covalent bonds on the surface of the polyamide layer and making the polyamide layer more compact.

[0010] Although the deboron removal rate of the membrane obtained in this patent document can reach more than 90%, the permeate flux is less than 11.85 GFD and the desalination rate is less than 99.61%, which is lower than the 99.80% level of common seawater desalination reverse osmosis membrane products on the market.

[0011] When reverse osmosis membranes need to be stored for a long time, in order to avoid the degradation of various properties of dry membrane elements during storage, wet elements are usually protected by a protective solution such as a standard protective solution of 1 wt% food-grade sodium metabisulfite or sodium bisulfite to ensure the performance stability of the membrane during storage. In this regard, some researchers have also developed new protective solutions.

[0012] Patent document CN118846815A provides a preservation solution for reverse osmosis membrane elements, comprising sodium ions, chloride ions, polyvalent cations, ether polymers, non-oxidizing bactericides, and a solvent, wherein the solvent includes water. This preservation solution enables the membrane elements to maintain stable permeate flow, desalination rate, and boron removal rate even after long-term storage. However, it primarily employs a method of preserving dry membrane elements by immersing them in the corresponding protective solution to form wet membrane elements, which are then sealed in packaging bags.

[0013] For membrane production, when the process is stable, it is not necessary to test each membrane element with raw water (sampling tests can be used), otherwise it will increase the cost of production and transportation. Therefore, in order to reduce the overall cost and selling price and reduce the cost per ton of water for seawater desalination, dry membrane elements are mostly sold. However, existing technology does not mention much about the performance stability of dry membrane elements after they are rolled up during storage.

[0014] Therefore, although some researchers have focused on improving the boron removal performance of seawater desalination reverse osmosis membranes, it is still impossible to achieve a balance between flux, desalination, and boron removal. In addition, in the current preparation methods, the concentration of amine monomers in the aqueous solution containing amine monomers used in the industrial-scale preparation of seawater desalination reverse osmosis membranes is relatively high. Furthermore, most researchers have not paid attention to the changes in the permeation and separation performance of the prepared membranes when stored in dry membrane form for a certain period of time while balancing flux, desalination, and boron removal. Summary of the Invention

[0015] The problem the invention aims to solve

[0016] The purpose of this invention is to overcome the above-mentioned shortcomings of the existing technology, develop a new method for preparing seawater desalination reverse osmosis membrane, and provide a seawater desalination reverse osmosis membrane that has excellent desalination rate, deboronization rate and flux, and maintains stable performance during long-term storage in the form of a dry membrane.

[0017] Solution for solving the problem

[0018] In order to achieve the above-mentioned objectives, the inventors conducted in-depth research and discovered that:

[0019] Introducing a flux-enhancing compound consisting of a co-solvent and a plasticizer into an organic phase solution containing acyl chloride monomers is beneficial for optimizing the initial polyamide layer structure. Furthermore, by applying an ethanol solution containing acyl chloride monomers for swelling modification, the ethanol causes the initial polyamide layer to swell, promoting the diffusion of more amine monomers. The secondary introduction of acyl chloride monomers promotes a secondary interfacial polymerization reaction, which is beneficial for improving the compactness of the polyamide layer, reducing the pore size of the polyamide layer, and improving the deboronization performance.

[0020] By introducing acyl chloride monomers to carry out secondary interfacial polymerization with amine monomers that did not react when the initial polyamide layer was formed, it is beneficial to consume more amine monomers. Therefore, it is beneficial to reduce the amount of amine leaching per unit area in the final finished membrane and to prevent or mitigate changes in the structure and properties of the membrane during storage.

[0021] Furthermore, treatment with an aqueous solution containing glycerol and tea polyphenols is beneficial for improving the performance stability of the membrane during dry membrane storage.

[0022] This invention provides a method for preparing a seawater desalination reverse osmosis membrane, which includes the following steps:

[0023] Prepare a base film, the base film comprising a support material and a polymer porous support layer formed on the support material, the polymer porous support layer being formed by a casting solution comprising a polymer and a solvent;

[0024] The base film is contacted with an aqueous solution containing amine monomers;

[0025] It is then contacted with an organic phase solution containing an acyl chloride monomer having two or more acyl chloride groups, a flux-enhancing compound, and an organic solvent, wherein the flux-enhancing compound is composed of a co-solvent and a plasticizer;

[0026] Contact with an ethanol solution containing acyl chloride monomers having 1 to 2 acyl chloride groups;

[0027] Cleaning;

[0028] Treatment was performed using an aqueous solution containing glycerol and tea polyphenols;

[0029] dry.

[0030] In the preparation method of the present invention, the supporting material is a non-woven fabric, and the polymer is at least one selected from bisphenol A polysulfone, polyarylsulfone, sulfonated polysulfone, polyethersulfone, polyvinylidene fluoride, polyacrylonitrile, and polyetheretherketone.

[0031] In the preparation method of the present invention, the amine monomer is an aromatic amine monomer having two or more amino groups, and the aromatic amine monomer having two or more amino groups is selected from one or more of m-phenylenediamine, p-phenylenediamine, o-phenylenediamine, mesentyltriamine, 2,5-diaminobenzoic acid, 3,5-diaminobenzoic acid, 2,4-diaminotoluene, and 2,5-diaminotoluene. Based on the total weight of the aqueous solution, the concentration of the amine monomer is 1 to 10 wt%.

[0032] In the preparation method of the present invention, the acyl chloride monomer having two or more acyl chloride groups is selected from one or more of pyromellitic tricarboxylic acid chloride, terephthaloyl chloride, isophthaloyl chloride, phthaloyl chloride, 2,5-furandicarboxylic acid chloride, 2,6-naphthalenedicarboxylic acid chloride, and 2,6-pyridine dicarbonyl chloride. Based on the total weight of the organic phase solution, the concentration of the acyl chloride monomer having two or more acyl chloride groups is 0.05~1.0 wt%.

[0033] In the preparation method of the present invention, the co-solvent is an amphiphilic co-solvent, preferably, the amphiphilic co-solvent is one or more selected from tetrahydrofuran, acetone, 2-butanone, 1-butanone, isopropanol and n-propanol; the plasticizer is an epoxy fatty acid ester, preferably, the epoxy fatty acid ester is one or more selected from epoxy fatty acid methyl ester, epoxy fatty acid ethyl ester, epoxy fatty acid butyl ester and epoxy fatty acid octyl ester; the organic solvent is an alkane solvent, preferably, the alkane solvent is at least one selected from n-hexane, n-heptane, cyclohexane, Isopar G, Isopar E, Isopar L, Isopar H and Isopar M.

[0034] In the preparation method of the present invention, the content of the co-solvent is 0.5~3wt% based on the total weight of the organic phase solution; preferably, the mass ratio of the co-solvent to the plasticizer is 5:1~10:1.

[0035] In the preparation method of the present invention, the molar volume of the acyl chloride monomer having 1-2 acyl chloride groups is less than 180 cm³. 3 / mol, preferably, the acyl chloride monomer having 1 to 2 acyl chloride groups is selected from propionyl chloride, furfural chloride, heptanyl chloride, terephthaloyl chloride, hexanoyl chloride, fumaroyl chloride, cinnamoyl chloride, acryloyl chloride, crotonyl chloride, malonyl chloride, methacryloyl chloride, methyl oxaloyl chloride, n-butyroyl chloride, 1-piperidinyl chloride, isobutyroyl chloride, nicotinyl chloride, benzoyl chloride, 6-chloronicotinyl chloride, 2-naphthoyl chloride, isophthaloyl chloride, 2,4-dichlorobenzoyl chloride, phthaloyl chloride, methyl malonyl chloride, cyclohexyl chloride, 3,5-dinitrobenzoyl chloride, 2-nitrobenzoyl chloride, 3-nitrobenzoyl chloride, 4-nitrobenzoyl chloride, and m-chlorobenzoyl chloride.

[0036] The preparation method of the present invention further includes an auxiliary agent and an acid-binding agent in the aqueous phase solution. Preferably, the auxiliary agent includes camphor sulfonic acid, and the content of the auxiliary agent is 1-10 wt% based on the total weight of the aqueous phase solution. Preferably, the acid-binding agent is an alkaline substance, and the alkaline substance is one or more selected from sodium hydroxide, potassium hydroxide, potassium dihydrogen phosphate and triethylamine.

[0037] The preparation method of the present invention, wherein the cleaning includes cleaning with n-hexane and cleaning with water, preferably, the cleaning with water includes cleaning with water at a temperature of 60~90°C and cleaning with water at a temperature of 20~30°C in sequence.

[0038] The present invention also provides a seawater desalination reverse osmosis membrane prepared by the method of the present invention.

[0039] The effects of the invention

[0040] The seawater desalination reverse osmosis prepared by the method of the present invention can simultaneously achieve excellent desalination rate, deboronization rate and flux, and maintain stable performance during long-term storage in the form of dry membrane. In addition, it has excellent alkali resistance.

[0041] The preparation process of this invention can be improved based on the existing seawater desalination reverse osmosis membrane production process. The preparation method is simple, easy to operate, requires no equipment modification, has low production cost and high production efficiency, and can be effectively used for the industrial-scale production of seawater desalination reverse osmosis membranes. Attached Figure Description

[0042] Figure 1The surface and cross-sectional structures of the reverse osmosis membranes prepared in the comparative example and Example 1 are shown. Detailed Implementation

[0043] Various exemplary embodiments, features, and aspects of the present invention will be described in detail below. The term "exemplary" as used herein means "serving as an example, embodiment, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as superior to or better than other embodiments.

[0044] Furthermore, to better illustrate the present invention, numerous specific details are set forth in the following detailed embodiments. Those skilled in the art should understand that the present invention can be practiced without certain specific details. In other instances, methods, means, apparatus, and steps well known to those skilled in the art have not been described in detail in order to highlight the spirit of the present invention.

[0045] Unless otherwise stated, all units used in this specification are international standard units, and all numerical values ​​and ranges appearing in this invention should be understood to include systematic errors that are unavoidable in industrial production.

[0046] In this specification, the word "may" has two meanings: to perform a certain process and not to perform a certain process.

[0047] In this specification, references to "some specific / preferred embodiments," "other specific / preferred embodiments," "implementation," etc., refer to specific elements (e.g., features, structures, properties, and / or characteristics) related to that embodiment, which are included in at least one of the embodiments described herein and may or may not be present in other embodiments. Furthermore, it should be understood that these elements may be combined in any suitable manner in various embodiments.

[0048] In this specification, the range of values ​​referred to as "value A to value B" refers to the range including the endpoint values ​​A and B.

[0049] This invention provides a method for preparing a seawater desalination reverse osmosis membrane, which includes the following steps:

[0050] Prepare a base film, the base film comprising a support material and a polymer porous support layer formed on the support material, the polymer porous support layer being formed by a casting solution comprising a polymer and a solvent;

[0051] The base film is contacted with an aqueous solution containing amine monomers;

[0052] It is then contacted with an organic phase solution containing an acyl chloride monomer having two or more acyl chloride groups, a flux-enhancing compound, and an organic solvent, wherein the flux-enhancing compound is composed of a co-solvent and a plasticizer;

[0053] Contact with an ethanol solution containing acyl chloride monomers having 1 to 2 acyl chloride groups;

[0054] Cleaning;

[0055] Treatment was performed using an aqueous solution containing glycerol and tea polyphenols;

[0056] dry.

[0057] Preferably, the support material is non-woven fabric. There are no particular limitations on the material of the non-woven fabric, which can be, for example, polyester PET, polyethylene PE, or polypropylene PP.

[0058] Preferably, the polymer is at least one selected from bisphenol A type polysulfone, polyarylsulfone, sulfonated polysulfone, polyethersulfone, polyvinylidene fluoride, polyacrylonitrile, and polyetheretherketone. The molecular weight cutoff of the polymer is 200,000 to 400,000 Daltons. The thickness of the polymer porous support layer is not particularly limited and can be, for example, 30 to 70 micrometers. The solvent in the casting solution is not particularly limited, as long as it can dissolve the polymer; it can be, for example, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, acetone, or tetrahydrofuran.

[0059] Preferably, the amine monomer is an aromatic amine monomer having two or more amino groups, and the aromatic amine monomer having two or more amino groups is selected from one or more of m-phenylenediamine, p-phenylenediamine, o-phenylenediamine, mesentyltriamine, 2,5-diaminobenzoic acid, 3,5-diaminobenzoic acid, 2,4-diaminotoluene and 2,5-diaminotoluene.

[0060] Based on the total weight of the aqueous solution, the concentration of the amine monomer is 1-10 wt%. When the concentration is within this range, the water flux and desalination rate of the prepared membrane can be better balanced, which is more conducive to the preparation of seawater desalination reverse osmosis membranes that can be better applied in practice. More preferably, the concentration is 2-6 wt%.

[0061] The aqueous solution further comprises an additive and an acid-binding agent. Preferably, the additive comprises camphor sulfonic acid, which primarily functions as follows: firstly, as a weak organic acid, it can work with the acid-binding agent to regulate / neutralize the hydrogen chloride produced during interfacial polymerization; secondly, it can reduce the surface tension of the aqueous solution to promote the uniform adsorption of amine monomers on the base film surface, ensuring the uniformity of the polyamide layer prepared by interfacial polymerization. Preferably, the additive content is 1-10 wt% based on the total weight of the aqueous solution. More preferably, the content is 2-8 wt%.

[0062] The acid-binding agent primarily absorbs the hydrogen chloride produced during interfacial polymerization to promote the reaction. Preferably, the acid-binding agent is an alkaline substance, selected from one or more of sodium hydroxide, potassium hydroxide, potassium dihydrogen phosphate, and triethylamine. The amount of acid-binding agent added can be adjusted according to the concentration of amine monomers in the aqueous solution, and the addition of the acid-binding agent makes the pH value of the aqueous solution approximately 11.

[0063] There are no particular limitations on the method of contacting the base film with the aqueous solution containing amine monomers. The base film can be immersed in the aqueous solution or the aqueous solution can be applied to the base film by coating.

[0064] Preferably, the coating method can be slit coating or similar techniques. By providing a coating head on the polymer porous support layer side, the aqueous solution is applied only to the surface of the base film, i.e., the polymer porous support layer side, reducing the residue of the aqueous solution on the back side of the base film, i.e., the nonwoven fabric side. Preferably, the coating amount of the aqueous solution is 70~100 g / m³. 2 The coating temperature is 15~30℃. More preferably, after coating, the residual aqueous phase solution on the film surface is dried by blowing after 20~60 seconds until no obvious water droplets are present on the film surface. Even more preferably, an air gun is used for drying.

[0065] There are no particular limitations on the method of contacting the base film with the organic phase solution; preferably, it is applied by coating. More preferably, it is applied by slot coating, and the coating amount of the organic phase solution is 30~120 g / m. 2 More preferably 50~80g / m 2 The coating temperature is 15~30℃.

[0066] Preferably, the acyl chloride monomer having two or more acyl chloride groups is selected from one or more of pyromellitic tricarboxylic acid chloride, terephthaloyl chloride, isophthaloyl chloride, orthophthaloyl chloride, 2,5-furandicarboxylic acid chloride, 2,6-naphthalenedicarboxylic acid chloride, and 2,6-pyridine dicarbonyl chloride.

[0067] Preferably, based on the total weight of the organic phase solution, the concentration of the acyl chloride monomer having two or more acyl chloride groups is 0.05~1.0 wt%. If the concentration is too high, it may easily lead to low or even no membrane flux; if the concentration is too low, it may result in a desalination rate that is difficult to meet the actual application requirements of seawater desalination. More preferably, the concentration is 0.15~0.5 wt%.

[0068] Preferably, the cosolvent is an amphiphilic cosolvent. The purpose of selecting an amphiphilic cosolvent is to promote the diffusion of amine monomers into the organic phase, thereby increasing the thickness of the polyamide layer of the prepared membrane and regulating the structure of the polyamide layer, thus optimizing the membrane's flux and desalination performance.

[0069] Preferably, the amphiphilic co-solvent is one or more selected from tetrahydrofuran, acetone, 2-butanone, 1-butanone, isopropanol, and n-propanol, and the content of the co-solvent is 0.5 to 3 wt% based on the total weight of the organic phase solution. More preferably, the content is 1 to 3 wt%.

[0070] The plasticizer is an epoxy fatty acid ester, preferably one or more selected from epoxy fatty acid methyl ester, epoxy fatty acid ethyl ester, epoxy fatty acid butyl ester and epoxy fatty acid octyl ester.

[0071] Preferably, the mass ratio of co-solvent to plasticizer is 5:1 to 10:1. When the mass ratio is within this range, the prepared membrane can achieve both better flux and desalination rate.

[0072] The main reason for choosing to use a combination of cosolvent and plasticizer is that if only a small amount of cosolvent is added, the increase in membrane flux is limited. When the content of cosolvent is increased, the increase in membrane flux is significant, but the desalination rate of the membrane may also decrease significantly. Furthermore, when the membrane is subsequently modified using an ethanol solution containing acyl chloride monomers with 1 to 2 acyl chloride groups, the desalination rate of the membrane may not meet the high requirements of practical applications.

[0073] Introducing a small amount of epoxy fatty acid ester plasticizer while using a co-solvent allows for more effective optimization of the movement and arrangement of polyamide chains, resulting in a membrane with a relatively better desalination rate at the same flux increase. Furthermore, with the addition of plasticizer, the membrane prepared after subsequent modification using an ethanol solution containing acyl chloride monomers with 1-2 acyl chloride groups exhibits even better performance. Simultaneously, the introduced amphiphilic co-solvent, due to its water solubility, promotes the diffusion of more amine monomers into the polyamide layer, facilitating the participation of more amine monomers in the reaction during subsequent modification and thus enhancing the removal performance of the prepared membrane.

[0074] The organic solvent is an alkane solvent, preferably, the alkane solvent is at least one selected from n-hexane, n-heptane, cyclohexane, Isopar G, Isopar E, Isopar L, Isopar H and Isopar M.

[0075] Preferably, after applying the organic phase solution, the membrane is allowed to stand at room temperature (20-30°C) for 1-3 minutes to promote the full progress of the interfacial polymerization reaction and form a complete polyamide layer. More preferably, the initial seawater desalination reverse osmosis membrane is obtained by blowing the residual organic phase solution on the membrane surface with an air gun.

[0076] Next, it is contacted with an ethanol solution containing acyl chloride monomers having 1-2 acyl chloride groups. Preferably, the ethanol solution containing acyl chloride monomers having 1-2 acyl chloride groups is applied by coating to perform swelling modification treatment. Preferably, it is coated only on the side containing the polyamide layer, the main purpose being that swelling occurs only on one side, and the ethanol solution diffuses only from the polyamide layer side to the base film side; the coating temperature is 25±5℃, and the coating amount is 30-60 g / m². 2 .

[0077] The main purpose of this process is twofold: First, during the interfacial polymerization reaction, a dense polyamide layer is formed in the initial stage. This barrier hinders the diffusion of amine monomers. As the polyamide layer thickens, the diffusion resistance of amine monomers increases further, the reaction rate slows down, and the polyamide layer eventually stops growing. Therefore, by using ethanol for swelling, the amine monomers can diffuse again and react with the residual acyl chloride monomers, further improving the compactness of the prepared membrane. Second, the ethanol solution causes the membrane to swell. Some small molecular weight substances in the swollen polyamide layer will fall off during subsequent water washing, leading to a decrease in the desalination rate of the membrane. Therefore, a small molecule substance with 1-2 acyl chloride groups is introduced into this process. This substance diffuses back into the polyamide layer and cross-links with the amine monomers that diffused again due to swelling and the unreacted amine monomers on the polyamide chains, further fixing the small molecular weight polyamide chains and ensuring the compactness of the polyamide layer of the membrane, thereby improving its boron removal rate from water.

[0078] Preferably, the molar volume of the acyl chloride monomer having 1-2 acyl chloride groups is less than 180 cm³. 3 / mol. The molar volume is calculated by dividing the molecular weight of the substance by its density. When the molar volume is too large, it may not be able to enter the polyamide layer, resulting in a failure to improve the removal performance of the prepared membrane.

[0079] Preferably, the acyl chloride monomer having 1 to 2 acyl chloride groups is selected from one or more of propionyl chloride, furfural chloride, heptanyl chloride, terephthaloyl chloride, hexanoyl chloride, fumaroyl chloride, cinnamoyl chloride, acryloyl chloride, crotonyl chloride, malonyl chloride, methacryloyl chloride, methyl oxaloyl chloride, n-butyroyl chloride, 1-piperidinyl chloride, isobutyroyl chloride, nicotinyl chloride, benzoyl chloride, 6-chloronicotinyl chloride, 2-naphthoyl chloride, isophthaloyl chloride, 2,4-dichlorobenzoyl chloride, phthaloyl chloride, methylmalonyl chloride, cyclohexyl chloride, 3,5-dinitrobenzoyl chloride, 2-nitrobenzoyl chloride, 3-nitrobenzoyl chloride, 4-nitrobenzoyl chloride, and m-chlorobenzoyl chloride.

[0080] Preferably, based on the total weight of the ethanol solution of the acyl chloride monomer having 1-2 acyl chloride groups, the concentration of the acyl chloride monomer having 1-2 acyl chloride groups is 0.05-0.5 wt%. When the concentration is below 0.05 wt%, the effect of improving the boron removal rate may be slightly worse; when the concentration is above 0.5 wt%, the flux of the prepared membrane may be slightly lower.

[0081] Preferably, after applying an ethanol solution of an acyl chloride monomer having 1-2 acyl chloride groups, the solution is left on the film surface for 10-20 seconds to complete the swelling and secondary interfacial polymerization reaction.

[0082] Preferably, the residual ethanol solution on the film surface is then dried using an air knife to ensure that the ethanol on the film surface is dry and the polyamide layer shrinks. More preferably, the drying process lasts for 10 to 15 seconds.

[0083] Preferably, the cleaning process includes cleaning with n-hexane and cleaning with water. Preferably, the cleaning with water includes cleaning with water at a temperature of 60-90°C and cleaning with water at a temperature of 20-30°C in sequence.

[0084] The purpose of using n-hexane for cleaning is to promote the reaction of residual and secondary introduced acyl chloride monomers with amine monomers and to wash away unreacted acyl chloride monomers, thereby improving the removal performance of the prepared membrane. There is no particular limitation on the cleaning time, which can be, for example, 0.5 to 3 minutes; preferably, the n-hexane solution on the membrane surface is dried using a double-sided air knife after cleaning.

[0085] The purpose of water washing is to remove unreacted monomers that remain in the membrane. There is no particular time limit for washing with hot water at a temperature of 60~90℃, for example, it can be 3~8 minutes. There is no particular time limit for washing with room temperature water at a temperature of 20~30℃, for example, it can be 3~10 minutes.

[0086] Preferably, the membrane is dipped in an aqueous solution containing glycerol and tea polyphenols for pore retention treatment. The concentrations of glycerol and tea polyphenols are not limited; based on the total weight of the aqueous solution, the concentration of glycerol can be, for example, 10-15 wt%, and the concentration of tea polyphenols can be, for example, 0.5-1.5 wt%. The temperature of the aqueous solution is not particularly limited and can be, for example, 25 ± 3 °C. The dipping time is not particularly limited and can be, for example, 1-5 minutes, to ensure that the pore-retention solution enters the membrane pores.

[0087] Then, drying is performed. Preferably, the drying method is forced air drying, the temperature is 60~80℃, and the time is 3~10 minutes to ensure that the film is completely dry.

[0088] The present invention also provides a seawater desalination reverse osmosis membrane prepared by the above method.

[0089] The seawater desalination reverse osmosis prepared by the method of the present invention can simultaneously achieve excellent desalination rate, deboronization rate and flux, and maintain stable performance during long-term storage in the form of dry membrane. In addition, it has excellent alkali resistance.

[0090] The water flux can reach 15-20 GFD, the sodium chloride removal rate is higher than 99.84%, reaching a maximum of 99.91%, and the boron removal rate is greater than 90%, reaching a maximum of over 93% (test conditions: 32000 mg / L sodium chloride + 5 ppm boric acid aqueous solution, pressure 800 psi, temperature 25℃). It also exhibits better alkali resistance. Furthermore, after being rolled into membrane elements and stored in dry membrane form for 60 days, the prepared membrane also shows more stable permeation and removal performance. This seawater desalination reverse osmosis membrane can be applied in fields such as material concentration and seawater desalination.

[0091] Example

[0092] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0093] Performance testing

[0094] Permeation and separation performance (i.e., flux, desalination rate, and boron removal rate) tests: To test the performance of the prepared seawater desalination reverse osmosis membrane, the membrane was tested on a cross-flow membrane testing platform. The test conditions were: 32000 mg / L sodium chloride solution, 5 ppm boric acid, operating pressure 800 psi, temperature 25℃, and pH 7. The stabilization time was 60 minutes.

[0095] Alkali resistance test: The dried membrane was immersed in an aqueous solution containing 0.2 wt% sodium hydroxide for 120 hours at 25°C; the membrane performance was then tested after rinsing with pure water.

[0096] Membrane element performance testing: To test the performance of the prepared seawater desalination reverse osmosis membrane element, the prepared seawater desalination reverse osmosis membrane element was tested on the membrane element test bench. The test conditions were: 32000 mg / L sodium chloride solution, 5 ppm boric acid, operating pressure 800 psi, temperature 25℃, pH value 7, and recovery rate 8%. The test stabilization time was 60 minutes.

[0097] The water flux J of the membrane is calculated according to equation (1). w .

[0098] (1)

[0099] In the formula, m is the weight of the permeate (kg), and A0 is the effective area of ​​the membrane (m²). 2 ), where t is the test time (h).

[0100] The desalination rate R of the membrane is calculated according to equation (2):

[0101] (2)

[0102] In the formula, R is the desalination rate, in units of %; C f The concentration of the feed salt solution is expressed in mg / L; C p The concentration of the permeate is expressed in mg / L.

[0103] Comparative Example

[0104] Prepare a base film. Apply an aqueous solution containing 3.5 wt% m-phenylenediamine, 3.0 wt% camphor sulfonic acid, and 1.5 wt% triethylamine (coating amount 90 g / m²) to the surface of the base film using a slit coating method. 2 After standing for 30 seconds to allow for uniform adsorption of the aqueous solution, remove the membrane and blow dry any remaining moisture until no droplets are visible on the membrane surface. Then, use a slit coating method to coat a hexane solution containing 0.2 wt% trimesoyl chloride (coating amount 70 g / m²). 2 After that, it is left to stand for 90 seconds to complete the initial interfacial polymerization reaction; the membrane after the reaction is completed is placed in an oven at room temperature (25±3℃), and the n-hexane solution on the membrane surface is evaporated by blowing air. Then, it is washed again with pure n-hexane solution to promote the polymerization reaction and wash away unreacted monomers; after the n-hexane on the membrane surface is dried, it is washed with 70℃ hot water for 5 minutes and pure water at room temperature (25±3℃) for 5 minutes. After immersion coating with an aqueous solution containing 12wt% glycerol + 1wt% tea polyphenols for 3 minutes to preserve the pores, it is dried in an oven at 70℃ for 5 minutes to obtain the final seawater desalination reverse osmosis membrane.

[0105] Comparative Example 1

[0106] Prepare a base film. Apply an aqueous solution containing 3.5 wt% m-phenylenediamine, 3.0 wt% camphor sulfonic acid, and 1.5 wt% triethylamine (coating amount 90 g / m²) to the surface of the base film using a slit coating method. 2 After standing for 30 seconds to allow for uniform adsorption of the aqueous solution, remove the membrane and blow dry any remaining moisture until no droplets are visible on the membrane surface. Then, use a slit coating method to coat a hexane solution containing 0.2 wt% trimesoyl chloride and flux-enhancing compound (2 wt% 2-butanone and 0.25 wt% epoxy fatty acid methyl ester) (coating amount 70 g / m²). 2After that, it is left to stand for 90 seconds to complete the initial interfacial polymerization reaction; the membrane after the reaction is completed is placed in an oven at room temperature (25±3℃), and the n-hexane solution on the membrane surface is evaporated by blowing air. Then, it is washed again with pure n-hexane solution to promote the polymerization reaction and wash away unreacted monomers; after the n-hexane on the membrane surface is dried, it is washed with 70℃ hot water for 5 minutes and pure water at room temperature (25±3℃) for 5 minutes. After immersion coating with an aqueous solution containing 12wt% glycerol + 1wt% tea polyphenols for 3 minutes to preserve the pores, it is dried in an oven at 70℃ for 5 minutes to obtain the final seawater desalination reverse osmosis membrane.

[0107] Example 1

[0108] Prepare a base film. Apply an aqueous solution containing 3.5 wt% m-phenylenediamine, 3.0 wt% camphor sulfonic acid, and 1.5 wt% triethylamine (coating amount 90 g / m²) to the surface of the base film using a slit coating method. 2 After standing for 30 seconds to allow for uniform adsorption of the aqueous solution, remove the membrane and blow dry any remaining moisture until no droplets are visible on the membrane surface. Then, use a slit coating method to coat a hexane solution containing 0.2 wt% trimesoyl chloride and flux-enhancing compound (2 wt% 2-butanone and 0.25 wt% epoxy fatty acid methyl ester) (coating amount 70 g / m²). 2 Afterward, allow it to stand for 90 seconds to complete the initial interfacial polymerization reaction; place the membrane after the reaction in an oven at room temperature (25±3℃), and use air blowing to cause the n-hexane solution on the membrane surface to evaporate; then, at room temperature (25±3℃), apply a 0.2wt% anhydrous ethanol solution of isophthaloyl chloride to the membrane surface using a slit coating method (coating amount 50g / m²). 2 After a 15-second pause, the ethanol on the membrane surface is evaporated by blowing air. The membrane is then cleaned with a pure hexane solution to promote the polymerization reaction and remove unreacted monomers. After the hexane on the membrane surface is dried, it is washed with 70°C hot water for 5 minutes and then with pure water at room temperature (25±3°C) for 5 minutes. After immersion in an aqueous solution containing 12wt% glycerol + 1wt% tea polyphenols for 3 minutes to preserve the pores, it is dried in a 70°C oven for 5 minutes to obtain the final seawater desalination reverse osmosis membrane.

[0109] The difference between Example 1 and Comparative Example 1 is that Example 1 adds a process of treatment using an anhydrous ethanol solution containing acyl chloride monomer.

[0110] Example 2

[0111] The preparation process is the same as in Example 1, except that isophthaloyl chloride is replaced with terephthaloyl chloride.

[0112] Example 3

[0113] The preparation process is the same as in Example 1, except that isophthaloyl chloride is replaced with benzoyl chloride.

[0114] Example 4

[0115] The preparation process is the same as in Example 1, except that isophthaloyl chloride is replaced with n-butyryl chloride.

[0116] Example 5

[0117] The preparation process is the same as in Example 1, except that isophthaloyl chloride is replaced with methacryloyl chloride.

[0118] Example 6

[0119] The preparation process is the same as in Example 1, except that the flux-enhancing compounding agent in the organic phase solution is replaced with acetone and epoxidized fatty acid methyl ester.

[0120] Example 7

[0121] The preparation process is the same as in Example 1, except that the flux-enhancing compounding agent in the organic phase solution is replaced with tetrahydrofuran and epoxy fatty acid methyl ester.

[0122] Example 8

[0123] The preparation process is the same as in Example 1, except that the flux-enhancing compounding agent in the organic phase solution is replaced with 2-butanone and epoxide fatty acid butyl ester.

[0124] Example 9

[0125] The preparation process is the same as in Example 1, except that the flux-enhancing compounding agent in the organic phase solution is replaced with 2-butanone and octyl epoxide fatty acid ester.

[0126] Comparative Example 2

[0127] The preparation process is the same as in Example 1, except that there is no flux-enhancing compound in the organic phase solution.

[0128] Comparative Example 3

[0129] The preparation process is the same as in Example 1, except that the flux-enhancing compound is only 2-butanone.

[0130] Comparative Example 4

[0131] The preparation process is the same as in Example 1, except that the flux-enhancing compound is only epoxy fatty acid methyl ester.

[0132] The initial properties of the reverse osmosis membranes obtained from the above comparative examples and embodiments are listed in Table 1 below.

[0133] Table 1

[0134]

[0135] By comparing the comparative examples and comparative example 1, it can be seen that the flux of the prepared membrane increased significantly after the introduction of the flux-enhancing compound agent. However, the desalination and deboronization of the membrane both showed varying degrees of reduction.

[0136] Although the flux of the seawater desalination reverse osmosis membranes of Examples 1 to 9 prepared by the method of the present invention is lower than that of the comparative examples and comparative example 1, the water flux is still maintained at a level of more than 14.33 GFD, and can reach a maximum of 19.32 GFD, which can meet the needs of practical applications. In addition, the desalination rate of the membrane is maintained at an excellent level of more than 99.84%, and can reach a maximum of 99.91%. The boron removal rate is significantly increased to an excellent level of more than 90.18%, and can reach a maximum of 94.12%. That is, while taking into account both flux and desalination rate, the boron removal rate is also significantly increased.

[0137] In Comparative Example 2, since no flux-enhancing compound was added and only the membrane was modified using an ethanol solution containing acyl chloride monomer, although the membrane removal rate (desalination rate and deboronization rate) increased, the flux of the prepared membrane was only 8.62 GFD. This would result in a low flux of the wound membrane element, which would not meet the actual application requirements.

[0138] In Comparative Examples 3 and 4, since only one of the co-solvent and plasticizer was used, the prepared membranes either had too low a boron removal rate or too low a flux, that is, they could not simultaneously achieve both flux and boron removal rate.

[0139] The membranes prepared in the comparative example and Example 1 were structurally characterized. Figure 1 The surface and cross-sectional structures of the membranes are shown in the figure. It was found that more spherical and leaf-like structures grew in the surface structure of the membranes prepared in Example 1. This was mainly due to the growth of polyamide chains caused by the reaction of more amine monomers and acyl chloride monomers. From the cross-sectional structure, after swelling modification treatment with flux-enhancing compound and ethanol containing acyl chloride monomers, the overall thickness of the cross section increased and more leaves grew.

[0140] The performance changes of the membranes in the comparative examples and Examples 1 and 3 before and after the alkali resistance test are listed in Table 2 below.

[0141] Table 2

[0142]

[0143] The results showed that, compared with the membranes prepared in the comparative example, the membranes prepared in Examples 1 and 3 exhibited smaller fluctuations in various properties after the alkali resistance test compared with those before the alkali resistance test, that is, they showed better alkali resistance.

[0144] Comparative Example 5

[0145] The preparation process is the same as in Example 1, except that isophthaloyl chloride is replaced with dansyl chloride.

[0146] Comparative Example 6

[0147] The preparation process is the same as in Example 1, except that isophthaloyl chloride is replaced with dodecyl chloride.

[0148] The properties of the membranes prepared in Comparative Examples 5 and 6, as well as Examples 1 and 2, are listed in Table 3 below.

[0149] Table 3

[0150]

[0151] In Comparative Examples 5 and 6, since the molar volume of the introduced acyl chloride monomer does not meet the limitations of this invention, its volume is still larger than the pore size of the swollen polyamide. Therefore, it cannot effectively enter the polyamide layer to react and can only crosslink to a certain extent on the membrane surface. Although this crosslinking process can improve the boron removal performance of the prepared membrane to a certain extent, the improved boron removal rate is still less than 90%, which is slightly insufficient compared with the high boron removal rate of more than 90% of the membranes prepared in Examples 1 and 2.

[0152] Comparative Example 7

[0153] The preparation process is the same as in Example 1, except that the process of "coating the membrane surface with an anhydrous ethanol solution of isophthaloyl chloride at a concentration of 0.2wt% by coating, leaving it for 15 seconds, and then evaporating the ethanol on the membrane surface by blowing air" is changed to "reacting the membrane surface with an anhydrous ethanol solution of isophthaloyl chloride at a concentration of 0.2wt% by dip coating for 15 seconds and then drying the ethanol on the membrane surface by blowing air".

[0154] Comparative Example 8

[0155] The preparation process is the same as that of Comparative Example 7, except that isophthaloyl chloride is replaced with benzoyl chloride.

[0156] The properties of the membranes prepared in Comparative Examples 7 and 8, as well as Examples 1 and 3, are listed in Table 4 below.

[0157] Table 4

[0158]

[0159] In Examples 1 and 3, when swelling was performed using an ethanol solution containing acyl chloride monomers, a coating method was mainly used, meaning the coated solution existed only on one side of the polyamide layer, and swelling proceeded downwards. This helped ensure the flux of the prepared membrane. In Comparative Examples 7 and 8, a dip-coating method was used, meaning the ethanol solution containing acyl chloride monomers diffused from both sides, causing a large amount of amines and acyl chlorides to react at the bottom of the polyamide and in the base membrane. This resulted in a large number of water molecules being blocked from passing through the channels, greatly increasing the membrane's permeation resistance. Although the deboronization rate of the prepared membrane was as high as 95%, the membrane flux was reduced too much and may not meet the high requirements of practical applications.

[0160] Example 10

[0161] The preparation process is the same as in Example 1, except that the composition of the flux-enhancing compound is changed from "2wt% 2-butanone and 0.25wt% epoxy fatty acid methyl ester" to "2wt% 2-butanone and 0.20wt% epoxy fatty acid methyl ester".

[0162] Example 11

[0163] The preparation process is the same as in Example 1, except that the composition of the flux-enhancing compound is changed from "2wt% 2-butanone and 0.25wt% epoxy fatty acid methyl ester" to "2wt% 2-butanone and 0.4wt% epoxy fatty acid methyl ester".

[0164] Example 12

[0165] The preparation process is the same as in Example 1, except that the composition of the flux-enhancing compound is changed from "2wt% 2-butanone and 0.25wt% epoxy fatty acid methyl ester" to "3wt% 2-butanone and 0.38wt% epoxy fatty acid methyl ester".

[0166] The properties of the membranes prepared in Examples 1 and 10 to 12 are listed in Table 5 below.

[0167] Table 5

[0168]

[0169] In all the above embodiments, excellent desalination and boron removal rates are achieved, and the water flux also meets the needs of practical applications.

[0170] Post-storage performance test:

[0171] Comparative experiments were conducted using comparative examples, Example 1, and Example 3, with the comparative moisturizing solutions being an aqueous solution containing 12 wt% glycerol and an aqueous solution containing 12 wt% glycerol and 1 wt% tea polyphenols, respectively. 8-inch membrane elements were rolled up and stored for testing. The results are listed in Table 6 below.

[0172] Table 6

[0173]

[0174] As can be seen from the results in Table 6, compared with the membrane elements of the comparative example, the membrane elements obtained by the method of the present invention have better desalination and deboronization performance. Although the deboronization performance of the membrane elements is slightly lower than that of the membrane sheets, it is still greater than 90%, which can meet the needs of practical applications.

[0175] After 60 days of storage, compared with the membrane element of the comparative example, the membrane element obtained by the method of the present invention showed less reduction in desalination and deboronization performance, indicating that the membrane prepared by the present invention has better stability.

[0176] Furthermore, when tea polyphenols are added to an aqueous solution containing glycerol, the antioxidant properties of tea polyphenols can better ensure the stability of the membrane's various properties during storage.

[0177] Compared with the deboron removal rate of membranes prepared without the addition of tea polyphenols, the deboron removal rate of membrane elements prepared with the addition of tea polyphenols remained above 90% after 60 days of storage.

[0178] It should be noted that although the technical solution of the present invention has been described with specific examples, those skilled in the art will understand that the present invention should not be limited thereto.

[0179] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or technical improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A method for producing a seawater desalination reverse osmosis membrane, characterized by, It includes the following steps: Prepare a base film, the base film comprising a support material and a polymer porous support layer formed on the support material, the polymer porous support layer being formed by a casting solution comprising a polymer and a solvent; The base film is contacted with an aqueous solution containing amine monomers; It is then contacted with an organic phase solution containing an acyl chloride monomer having two or more acyl chloride groups, a flux-enhancing compounding agent, and an organic solvent, wherein the flux-enhancing compounding agent is composed of a co-solvent and a plasticizer, and the plasticizer is an epoxy fatty acid ester; Contact with an ethanol solution containing acyl chloride monomers having 1 to 2 acyl chloride groups; Cleaning; Treatment was performed using an aqueous solution containing glycerol and tea polyphenols; dry.

2. The preparation method according to claim 1, wherein the supporting material is a nonwoven fabric, and the polymer is at least one selected from bisphenol A polysulfone, polyarylsulfone, sulfonated polysulfone, polyethersulfone, polyvinylidene fluoride, polyacrylonitrile, and polyetheretherketone.

3. The preparation method according to claim 1 or 2, wherein the amine monomer is an aromatic amine monomer having two or more amino groups, and the aromatic amine monomer having two or more amino groups is selected from one or more of m-phenylenediamine, p-phenylenediamine, o-phenylenediamine, mesentyltriamine, 2,5-diaminobenzoic acid, 3,5-diaminobenzoic acid, 2,4-diaminotoluene, and 2,5-diaminotoluene, and the concentration of the amine monomer is 1 to 10 wt% based on the total weight of the aqueous solution.

4. The preparation method according to claim 1 or 2, wherein the acyl chloride monomer having two or more acyl chloride groups is selected from one or more of pyromellitic tricarboxylic acid chloride, terephthaloyl chloride, isophthaloyl chloride, phthaloyl chloride, 2,5-furandicarboxylic acid chloride, 2,6-naphthalenedicarboxylic acid chloride and 2,6-pyridine dicarbonyl chloride, and the concentration of the acyl chloride monomer having two or more acyl chloride groups is 0.05~1.0 wt% based on the total weight of the organic phase solution.

5. The preparation method according to claim 1 or 2, wherein the co-solvent is an amphiphilic co-solvent; the epoxy fatty acid ester is one or more selected from epoxy fatty acid methyl ester, epoxy fatty acid ethyl ester, epoxy fatty acid butyl ester and epoxy fatty acid octyl ester; and the organic solvent is an alkane solvent.

6. The preparation method according to claim 5, wherein the amphiphilic co-solvent is one or more selected from tetrahydrofuran, acetone, 2-butanone, 1-butanone, isopropanol and n-propanol, and the alkane solvent is at least one selected from n-hexane, n-heptane, cyclohexane, Isopar G, Isopar E, Isopar L, Isopar H and Isopar M.

7. The preparation method according to claim 1 or 2, wherein the content of the co-solvent is 0.5 to 3 wt% based on the total weight of the organic phase solution.

8. The preparation method according to claim 7, wherein the mass ratio of the co-solvent to the plasticizer is 5:1 to 10:

1.

9. The production method according to claim 1 or 2, wherein the acyl chloride-based monomer having 1 to 2 acyl chloride groups has a molar volume of less than 180 cm3 / mol. 3 / mol.

10. The preparation method according to claim 9, wherein the acyl chloride monomer having 1 to 2 acyl chloride groups is selected from propionyl chloride, furfural chloride, heptanyl chloride, terephthaloyl chloride, hexanoyl chloride, fumaroyl chloride, cinnamoyl chloride, acryloyl chloride, crotonyl chloride, malonyl chloride, methacryloyl chloride, methyl oxaloyl chloride, n-butyroyl chloride, 1-piperidinyl chloride, isobutyroyl chloride, nicotinyl chloride, benzoyl chloride, 6-chloronicotinyl chloride, 2-naphthoyl chloride, isophthaloyl chloride, 2,4-dichlorobenzoyl chloride, phthaloyl chloride, methylmalonyl chloride, cyclohexyl chloride, 3,5-dinitrobenzoyl chloride, 2-nitrobenzoyl chloride, 3-nitrobenzoyl chloride, 4-nitrobenzoyl chloride, and m-chlorobenzoyl chloride.

11. The preparation method according to claim 1 or 2, wherein the aqueous phase solution further comprises an auxiliary agent and an acid-binding agent.

12. The preparation method according to claim 11, wherein the auxiliary agent comprises camphor sulfonic acid, and the content of the auxiliary agent is 1-10 wt% based on the total weight of the aqueous solution; the acid-binding agent is an alkaline substance, and the alkaline substance is one or more selected from sodium hydroxide, potassium hydroxide, potassium dihydrogen phosphate and triethylamine.

13. The preparation method according to claim 1 or 2, wherein the cleaning comprises cleaning with n-hexane and cleaning with water.

14. The preparation method according to claim 13, wherein the water cleaning includes sequentially cleaning with water at a temperature of 60-90°C and cleaning with water at a temperature of 20-30°C.

15. A seawater desalination reverse osmosis membrane, prepared by the method according to any one of claims 1 to 14.

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