Preparation method of efficient boron-removing reverse osmosis membrane

Abstract

The invention belongs to the technical field of membrane separation, and particularly relates to a preparation method of an efficient boron-removing reverse osmosis membrane, which comprises the following steps: (1) sequentially soaking a polysulfone membrane in a glucoside solution, a mixed solution of m-phenylenediamine and diol and a trimesoyl chloride solution; (2) coating the surface of the membrane treated in the step (1) with a high iodide solution; and (3) heating the membrane obtained in the step (2) to obtain the efficient boron-removing reverse osmosis membrane. The process flow is simple, raw materials are cheap and easy to obtain, and the method is suitable for large-scale production of the reverse osmosis membrane; meanwhile, the prepared reverse osmosis membrane has relatively high boron rejection rate and permeation flux, and can be used for efficient boron removal treatment of water bodies such as seawater or brackish water.

Description

Technical Field

[0001] The invention belongs to the technical field of membrane separation, and in particular relates to a method for preparing a high-efficiency boron removal reverse osmosis membrane. Background Art

[0002] Boron is present in seawater, surface water and groundwater, and excessive boron can cause damage to plants and humans. Therefore, the World Health Organization stipulates that the boron content in drinking water should not exceed 2.4 mg / L.

[0003] Reverse osmosis technology is a membrane process that uses the pressure difference on both sides of the membrane as a driving force and the selective permeability of the semipermeable membrane to achieve separation. As an efficient separation technology, reverse osmosis membranes are widely used in the field of water treatment. Although they have good interception capabilities for ions and organic molecules, their removal rate for boron is low.

[0004] At present, there are two main methods to improve the boron removal rate of reverse osmosis membranes, namely, surface modification of reverse osmosis membranes and doping with multifunctional molecules or nanomaterials. For example, Duan et al. (Fabrication of high boron removal reverse osmosis membrane with broad industrial application prospect by introducing sulfonate groups through a polyvinyl alcohol coating, Journal of Membrane Science, 2022, 664: 121079) used disodium benzaldehyde disulfonate and polyvinyl alcohol to modify the surface of the reverse osmosis membrane, increasing the boron removal rate from 85.7% to 91.6%; Li et al. (Facile fabrication of hydroxyl-rich polyamide TFC RO membranes for enhanced boron removal performance, Desalination, 2022, 531: 115723) introduced HEA-co-AA copolymer into the reverse osmosis membrane by UV-assisted interfacial polymerization, increasing the boron removal rate from 84.2% to 92.8%; the patent application (CN202410074880.0) doped functionalized graphene into the reverse osmosis membrane to improve its boron removal rate and permeation flux. However, the above method is relatively complicated and costly, which limits its practical application. In addition, the improvement in the boron removal rate (or boron retention rate) and permeation flux of the modified reverse osmosis membrane is limited. Summary of the invention

[0005] The present invention aims to solve at least one of the problems existing in the above-mentioned prior art. To this end, the present invention provides a method for preparing a high-efficiency boron removal reverse osmosis membrane.

[0006] In order to achieve the above objectives, the specific technical solutions are as follows: A method for preparing a high-efficiency deboronization reverse osmosis membrane comprises the following steps: (1) The polysulfone membrane is sequentially immersed in a glucoside solution, a mixed solution of m-phenylenediamine and diol, and a trimesoyl chloride solution; (2) applying a high iodide solution to the surface of the membrane treated in step (1); (3) The membrane obtained by the treatment in step (2) is subjected to a heating treatment to obtain the high-efficiency deboronization reverse osmosis membrane.

[0007] Among them, m-phenylenediamine and trimesoyl chloride are polymerized to form a polyamide active layer; diol as a reactant can react with trimesoyl chloride to form polyester on the membrane surface, and high iodide can continue to react with diol to generate aldehyde. The above two steps can both increase the permeation flux of the reverse osmosis membrane and improve its boron retention rate.

[0008] Further, the glucoside solution is a mixture of one or more of dodecyl glucoside, dodecyl glucopyranoside, dodecyl-α-D-glucopyranoside, caffeic acid 3-β-D-glucoside or rhein-8-glucoside; the concentration of the glucoside solution is 0.05 wt% to 2 wt%, and the soaking treatment time of the glucoside solution is 1 minute to 30 minutes. Preferably, the solvent in the glucoside solution is water and ethanol, and the volume fraction of ethanol is 2% to 10%.

[0009] Furthermore, the diol is one or a mixture of 2,5-hexanediol, 1,2-butanediol, 1,5-pentanediol, 1,2-pentanediol or 1,7-heptanediol; the concentrations of m-phenylenediamine and diol are 0.01 wt% to 10wt% and 0.01 wt% to 2 wt% respectively, and the immersion time of the mixed solution of m-phenylenediamine and diol is 30 seconds to 1 hour.

[0010] Furthermore, the concentration of the trimesoyl chloride solution is 0.01 wt% to 1 wt%, and the immersion time of the trimesoyl chloride solution is 10 seconds to 5 minutes. Preferably, the solvent in the trimesoyl chloride solution is n-hexane.

[0011] Preferably, in the mixed solution of m-phenylenediamine and diol, the solvent is water-ethanol-ether, the ether is β, β'-dichlorodiethyl ether, ethyl butyl ether or 2-chloroethyl propyl ether, wherein the volume fractions of ethanol and ether are 0.1% to 5% and 0.05% to 2%, respectively. Ether as a co-solvent can enhance the water-n-hexane interface compatibility in this preparation process and promote the reaction and film formation.

[0012] Furthermore, the periodide solution is one or a mixture of periodic acid, sodium periodate, potassium periodate or ammonium periodate; the concentration of the periodide solution is 0.01 wt% to 1 wt%, and the coating standing time is 2 minutes to 30 minutes.

[0013] Preferably, in step (3), the heating temperature is 40-70° C. and the heating time is 30 s-20 min.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The process of the invention is simple, and the raw materials are cheap and readily available, and is suitable for large-scale production of reverse osmosis membranes; at the same time, the prepared reverse osmosis membrane has a high boron removal rate and permeation flux, and can be used for efficient boron removal treatment of water bodies such as seawater or brackish water. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The separation performance test of the reverse osmosis membrane under different test pressures in Example 1 of the present invention; Figure 2 This is a test of the separation performance of the reverse osmosis membrane in Example 1 of the present invention for feed solutions containing different concentrations of boron. DETAILED DESCRIPTION

[0016] The principles and features of the present invention are described below in conjunction with examples. The examples are only used to explain the present invention and are not used to limit the scope of the present invention. The experimental methods used in the following examples are conventional methods unless otherwise specified; the materials, reagents, etc. used in the following examples can be obtained from commercial channels unless otherwise specified.

[0017] In the following examples, the separation performance of the reverse osmosis membrane was tested under the conditions of 1.5 MPa and 25°C with 2000 ppm NaCl and 5 ppm boric acid as the raw liquid, where the permeate flux unit is Lm -2 h -1 bar -1 . Example 1

[0018] A method for preparing a high-efficiency deboronization reverse osmosis membrane comprises the following steps: (1) The polysulfone membrane was immersed in a water-ethanol mixed solution containing 0.05 wt% dodecylpyranoglucoside, wherein the volume fraction of ethanol was 2%, and then taken out after 1 minute; (2) immersing the membrane of step (1) in a water-ethanol-ethyl butyl ether ternary mixed solution containing 2 wt% m-phenylenediamine and 2 wt% 2, 5-hexanediol, wherein the volume fractions of ethanol and ethyl butyl ether are 0.1% and 2%, respectively, and taking out and removing the droplets on the membrane surface after 30 seconds; (3) Soaking the membrane of step (2) in a hexane solution containing 0.15 wt % trimesoyl chloride for 1 minute and taking it out; (4) applying an aqueous solution containing 1 wt% sodium periodate to the surface of the membrane in step (3), leaving it to stand for 2 minutes and then removing the solution; (5) The membrane obtained in (4) was heated at 60° C. for 5 minutes to obtain the high-efficiency deboronization reverse osmosis membrane.

[0019] Under the above test conditions, the performance of the prepared reverse osmosis membrane was tested: the boron removal rate was 94.6%, the NaCl rejection rate was 98.9%, and the permeation flux was 2.9 Lm-2h-1bar-1. Figure 1 As shown in the figure, the boron removal rate of the reverse osmosis membrane prepared in Example 1 under different test pressures is higher than 90%, the NaCl retention rate is about 99.0%, and the permeation flux is basically unchanged, indicating that the prepared reverse osmosis membrane has good anti-compaction ability; Figure 2 As shown, the boron removal rate of the reverse osmosis membrane prepared in Example 1 at different boron concentrations is higher than 90%, the NaCl retention rate is about 99.0%, and the permeation flux remains basically unchanged, indicating that the prepared reverse osmosis membrane has excellent separation performance under different water quality environments. Example 2

[0020] A method for preparing a high-efficiency deboronization reverse osmosis membrane comprises the following steps: (1) The polysulfone membrane was immersed in a water-ethanol mixed solution containing 2 wt% of rhein-8-glucoside, wherein the volume fraction of ethanol was 10%, and then taken out after 30 minutes; (2) immersing the membrane of step (1) in a water-ethanol-2-chloroethyl propyl ether ternary mixed solution containing 10 wt% m-phenylenediamine and 0.01 wt% 1, 2-pentanediol, wherein the volume fractions of ethanol and 2-chloroethyl propyl ether are 5% and 0.05%, respectively. After 1 hour, taking out and removing the droplets on the membrane surface; (3) Soaking the membrane of step (2) in a hexane solution containing 0.01 wt % trimesoyl chloride for 10 seconds and taking it out; (4) applying an aqueous solution containing 0.01 wt% periodic acid to the surface of the membrane in step (3), leaving it to stand for 30 minutes and then removing the solution; (5) The membrane obtained in (4) was heated at 60°C for 5 minutes to obtain a high-efficiency boron removal reverse osmosis membrane.

[0021] Under the above test conditions, the performance of the prepared reverse osmosis membrane was tested: the boron removal rate was 93.6%, the NaCl rejection rate was 98.7%, and the permeation flux was 2.3 Lm -2 h -1 bar -1 . Example 3

[0022] A method for preparing a high-efficiency deboronization reverse osmosis membrane comprises the following steps: (1) The polysulfone membrane was immersed in a water-ethanol mixed solution containing 1 wt% dodecyl glucoside, wherein the volume fraction of ethanol was 5%, and then taken out after 5 minutes; (2) immersing the membrane of step (1) in a water-ethanol-β, β'-dichlorodiethyl ether ternary mixed solution containing 0.01 wt% m-phenylenediamine and 1 wt% 1, 2-butanediol, wherein the volume fractions of ethanol and β, β'-dichlorodiethyl ether are 1% and 1.5%, respectively, and taking out and removing the droplets on the membrane surface after 30 minutes; (3) Soaking the membrane of step (2) in a hexane solution containing 1 wt% trimesoyl chloride for 5 minutes and taking it out; (4) applying an aqueous solution containing 0.5 wt% potassium periodate to the surface of the membrane in step (3), leaving it to stand for 15 minutes and then removing the solution; (5) The membrane obtained in (4) was heated at 60°C for 5 minutes to obtain a high-efficiency boron removal reverse osmosis membrane.

[0023] Under the above test conditions, the performance of the prepared reverse osmosis membrane was tested: the boron removal rate was 92.7%, the NaCl rejection rate was 98.6%, and the permeation flux was 3.1 Lm -2 h -1 bar -1 . Example 4

[0024] A method for preparing a high-efficiency deboronization reverse osmosis membrane comprises the following steps: (1) The polysulfone membrane was immersed in a water-ethanol mixed solution containing 1.5 wt% caffeic acid 3-β-D-glucoside, wherein the volume fraction of ethanol was 5%, and then taken out after 20 minutes; (2) immersing the membrane of step (1) in a water-ethanol-β, β'-dichlorodiethyl ether ternary mixed solution containing 5 wt% m-phenylenediamine and 1.5 wt% 1, 5-pentanediol, wherein the volume fractions of ethanol and β, β'-dichlorodiethyl ether are 2% and 1.5%, respectively, and taking out and removing the droplets on the membrane surface after 2 minutes; (3) Soaking the membrane of step (2) in a hexane solution containing 0.8 wt% trimesoyl chloride for 1 minute and taking it out; (4) applying an aqueous solution containing 0.1 wt% ammonium periodate to the surface of the membrane in step (3), leaving it to stand for 5 minutes and then removing the solution; (5) The membrane obtained in (4) was heated at 60°C for 5 minutes to obtain a high-efficiency boron removal reverse osmosis membrane.

[0025] Under the above test conditions, the performance of the prepared reverse osmosis membrane was tested: the boron removal rate was 94.2%, the NaCl rejection rate was 98.2%, and the permeation flux was 2.8 Lm -2 h -1 bar -1 . Example 5

[0026] A method for preparing a high-efficiency deboronization reverse osmosis membrane comprises the following steps: (1) The polysulfone membrane was immersed in a water-ethanol mixed solution containing 1 wt% caffeic acid 3-β-D-glucoside, where the volume fraction of ethanol was 6%, and then taken out after 25 minutes; (2) immersing the membrane of step (1) in a water-ethanol-2-chloroethyl propyl ether ternary mixed solution containing 1 wt% m-phenylenediamine, 1 wt% 1,5-pentanediol and 0.1 wt% 1,7-heptanediol, wherein the volume fractions of ethanol and 2-chloroethyl propyl ether are 1% and 0.15%, respectively. After 10 minutes, the membrane is taken out and the droplets on the membrane surface are removed; (3) Soaking the membrane of step (2) in a hexane solution containing 0.15 wt% trimesoyl chloride for 2 minutes and taking it out; (4) applying an aqueous solution containing 0.1 wt% periodic acid to the surface of the membrane in step (3), leaving it to stand for 5 minutes and then removing the solution; (5) The membrane obtained in (4) was heated at 60°C for 5 minutes to obtain a high-efficiency boron removal reverse osmosis membrane.

[0027] Under the above test conditions, the performance of the prepared reverse osmosis membrane was tested: the boron removal rate was 93.1%, the NaCl rejection rate was 98.6%, and the permeation flux was 2.9 Lm -2 h -1 bar -1 . Comparative Example 1

[0028] A method for preparing a high-efficiency deboronization reverse osmosis membrane comprises the following steps: (1) Soak the polysulfone membrane in a water-ethanol mixed solution, where the volume fraction of ethanol is 2%, and take it out after 1 minute; (2) immersing the membrane of step (1) in a water-ethanol-ethyl butyl ether ternary mixed solution containing 2 wt% m-phenylenediamine and 2 wt% 2, 5-hexanediol, wherein the volume fractions of ethanol and ethyl butyl ether are 0.1% and 2%, respectively, and taking out and removing the droplets on the membrane surface after 30 seconds; (3) Soaking the membrane of step (2) in a hexane solution containing 0.15 wt % trimesoyl chloride for 1 minute and taking it out; (4) applying an aqueous solution containing 1 wt% sodium periodate to the surface of the membrane in step (3), leaving it to stand for 2 minutes, and then removing the solution; (5) The membrane obtained in (4) was heated at 60°C for 5 minutes to obtain a high-efficiency boron removal reverse osmosis membrane.

[0029] Under the above test conditions, the performance of the prepared reverse osmosis membrane was tested: the boron removal rate was 89.2%, the NaCl rejection rate was 98.5%, and the permeation flux was 1.9 Lm -2 h -1 bar -1 Compared with Example 1, the boron removal rate, NaCl retention rate and permeation flux thereof are all decreased. Comparative Example 2

[0030] A method for preparing a high-efficiency deboronization reverse osmosis membrane comprises the following steps: (1) The polysulfone membrane was immersed in a water-ethanol mixed solution containing 0.05 wt% dodecylpyranoglucoside, wherein the volume fraction of ethanol was 2%, and then taken out after 1 minute; (2) immersing the membrane of step (1) in a water-ethanol-ethyl butyl ether ternary mixed solution containing 2 wt% m-phenylenediamine and 2 wt% 2, 5-hexanediol, wherein the volume fractions of ethanol and ethyl butyl ether are 0.1% and 2%, respectively, and taking out and removing the droplets on the membrane surface after 30 seconds; (3) Soaking the membrane of step (2) in a hexane solution containing 0.15 wt % trimesoyl chloride for 1 minute and taking it out; (4) The membrane obtained in (3) was heated at 60°C for 5 minutes to obtain a high-efficiency boron removal reverse osmosis membrane.

[0031] Under the above test conditions, the performance of the prepared reverse osmosis membrane was tested: the boron removal rate was 83.6%, the NaCl rejection rate was 98.9%, and the permeation flux was 1.2 Lm -2 h -1 bar -1 Compared with Example 1, the boron removal rate and permeation flux thereof are decreased, and the NaCl retention rate remains unchanged. Comparative Example 3

[0032] A method for preparing a high-efficiency deboronization reverse osmosis membrane comprises the following steps: (1) The polysulfone membrane was immersed in a water-ethanol mixed solution containing 0.05 wt% dodecylpyranoglucoside, wherein the volume fraction of ethanol was 2%, and then taken out after 1 minute; (2) immersing the membrane of step (1) in a ternary mixed solution of water-ethanol-ethyl butyl ether containing 2 wt% m-phenylenediamine, wherein the volume fractions of ethanol and ethyl butyl ether are 0.1% and 2%, respectively; after 30 seconds, taking out and removing the droplets on the membrane surface; (3) Soaking the membrane of step (2) in a hexane solution containing 0.15 wt% trimesoyl chloride for 1 minute and taking it out; (4) applying an aqueous solution containing 1 wt% sodium periodate to the surface of the membrane in step (3), leaving it to stand for 2 minutes, and then removing the solution; (5) The membrane obtained in (4) was heated at 60°C for 5 minutes to obtain a high-efficiency boron removal reverse osmosis membrane.

[0033] Under the above test conditions, the performance of the prepared reverse osmosis membrane was tested: the boron removal rate was 90.5%, the NaCl rejection rate was 98.2%, and the permeation flux was 2.2 Lm -2 h -1 bar -1 Compared with Example 1, the boron removal rate, NaCl retention rate and permeation flux thereof are all decreased.

[0034] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing an efficient deboronization reverse osmosis membrane, characterized in that: The preparation method comprises the following steps: (1) The polysulfone membrane is sequentially immersed in a glucoside solution, a mixed solution of m-phenylenediamine and diol, and a trimesoyl chloride solution; (2) applying a high iodide solution to the surface of the membrane treated in step (1); (3) The membrane obtained by the treatment in step (2) is subjected to a heating treatment to obtain the high-efficiency deboronization reverse osmosis membrane.

2. The preparation method according to claim 1, characterized in that: The glucoside solution is one or a mixture of dodecyl glucoside, dodecyl glucopyranoside, dodecyl-α-D-glucopyranoside, caffeic acid 3-β-D-glucoside or rhein-8-glucoside.

3. The preparation method according to claim 2, characterized in that: The concentration of the glucoside solution is 0.05 wt% to 2 wt%, and the soaking treatment time of the glucoside solution is 1 minute to 30 minutes.

4. The preparation method according to claim 1, characterized in that: The diol is one or a mixture of 2,5-hexanediol, 1,2-butanediol, 1,5-pentanediol, 1,2-pentanediol or 1,7-heptanediol.

5. The preparation method according to claim 4, characterized in that: The concentrations of the m-phenylenediamine and diol are 0.01 wt% to 10 wt% and 0.01 wt% to 2 wt% respectively, and the immersion time of the mixed solution of m-phenylenediamine and diol is 30 seconds to 1 hour.

6. The preparation method according to claim 4, characterized in that: In the mixed solution of m-phenylenediamine and diol, the solvent is water-ethanol-ether, and the ether is β, β'-dichlorodiethyl ether, ethyl butyl ether or 2-chloroethyl propyl ether.

7. The preparation method according to claim 1, characterized in that: The concentration of the trimesoyl chloride solution is 0.01wt% to 1wt%, and the immersion time of the trimesoyl chloride solution is 10 seconds to 5 minutes.

8. The preparation method according to claim 7, characterized in that: In the trimesoyl chloride solution, the solvent is n-hexane.

9. The preparation method according to claim 1, characterized in that: The periodide solution is one of periodic acid, sodium periodate, potassium periodate or ammonium periodate or a mixture of several of them.

10. The preparation method according to claim 9, characterized in that: The concentration of the high iodide solution is 0.01 wt% to 1 wt%, and the coating standing time is 2 minutes to 30 minutes.

Images