A method for preparing reverse osmosis membranes based on n-sulfenylaniline additives

Abstract

The application provides a method for preparing a high-performance reverse osmosis membrane based on an N-sulfenyl aniline additive. The preparation method introduces N-sulfenyl aniline as an organic phase additive under the preparation conditions of a conventional reverse osmosis membrane, and a polyamide separation layer is prepared on a polysulfone base membrane through interface polymerization control to obtain a high-performance reverse osmosis membrane. The additive can effectively reduce the thickness of the membrane, improve the crosslinking degree and hydrophilicity. Compared with a conventional polyamide reverse osmosis membrane, the modified membrane has a permeation flux of 58.3 L·m ‑2 ·h ‑1 ·MPa ‑1 , and a sodium chloride rejection rate of 99.23%, and shows higher water flux and excellent desalination performance. The method is simple in operation and low in cost, and provides a new idea and technical approach for preparing a high-performance polyamide reverse osmosis membrane.

Description

TECHNICAL FIELD

[0001] The application relates to a preparation method of a high-permeability reverse osmosis membrane, which is suitable for the fields of brackish water desalination, seawater desalination, wastewater treatment and the like. BACKGROUND

[0002] Due to the rapid development of social economy, the demand of human beings for fresh water resources has significantly increased, and at present, many regions in the world are facing the problem of water resource shortage. The membrane separation technology is widely applied in the fields of brackish water desalination, seawater desalination, wastewater treatment and the like due to the advantages of high separation efficiency, low cost, low energy consumption, simple operation, safety and stability and the like. However, the traditional composite reverse osmosis membrane prepared based on interfacial polymerization is subject to the 'trade-off' effect between the permeation flux and the selectivity, and gradually cannot meet the needs of people, and how to improve the water permeation flux without sacrificing the salt retention becomes the key idea for solving the problem.

[0003] Adding an additive is an important method for improving the membrane performance, and the introduction of the additive can improve the interfacial polymerization rate, reduce the thickness and resistance of the separation layer, or make the membrane surface more loose (the free volume is larger), and the roughness (the specific surface area) is larger, so that the flux of the composite membrane is improved. However, at present, the additive introduced in the reverse osmosis membrane is mainly a nano-particle additive, although the performance of the reverse osmosis membrane can be effectively improved, the synthesis and application process are relatively complex, and the aggregation of the nano-particles will form defects in the reverse osmosis membrane, thereby reducing the separation selectivity of the membrane. Therefore, in order to further improve the operation efficiency of the reverse osmosis membrane and reduce the operation cost, a simple method can be selected to introduce a small-molecule additive into the reverse osmosis membrane, so as to obtain certain economic benefits and social value. SUMMARY

[0004] The purpose of the application is to introduce a small-molecule N-sulfinyl aniline as an additive into an organic phase to regulate the interfacial polymerization process, so as to obtain a high-performance reverse osmosis membrane. The method is suitable for a wide range of applications, is easy to scale up, and makes up for the shortcomings of the prior art.

[0005] The technical scheme of the application is summarized as follows:

[0006] 1. A preparation method of a high-performance reverse osmosis membrane based on an N-sulfinyl aniline additive, comprising the steps that a water phase monomer solution is made to enter the holes of a porous support membrane in a soaking or coating or support-free mode, and then interfacial polymerization reaction is carried out between the water phase monomer solution and an organic phase solution containing an acid chloride monomer and an additive on the surface of the membrane, so as to form a reverse osmosis membrane.

[0007] 2. The method of claim 1, wherein after the interfacial polymerization to form the polyamide separation layer, the method further comprises the steps of: rinsing the surface of the reverse osmosis membrane with an organic solvent for 10-100 seconds; and drying the reverse osmosis membrane at a temperature of 25-95 °C for 30 seconds to 10 minutes to obtain the reverse osmosis membrane.

[0008] 3. The method of claim 1, wherein the aqueous phase solution is deposited on the surface of the porous support membrane for 30 seconds to 5 minutes, and wherein the aqueous phase monomer is one or more of m-phenylenediamine, p-phenylenediamine, o-phenylenediamine, benzidine, or other aromatic amines.

[0009] 4. The method of claim 1, wherein the organic phase solution comprises an acid chloride monomer, an additive, and an organic phase solvent, and wherein the acid chloride monomer is present in a mass fraction of 0.01-30 wt%, the additive is present in a concentration of 0.00001-5 wt%, and the organic phase solvent is present in a mass fraction of 65-99.98999 wt%.

[0010] 5. The method of claim 4, wherein the acid chloride monomer is one or more of trimesoyl chloride, isophthaloyl chloride, terephthaloyl chloride, cyclohexanetricarboxylic acid chloride, 1,2,3,4-cyclobutane tetracarboxylic acid chloride, 1,2,4,5-cyclohexane tetracarboxylic acid chloride, oxalyl chloride, malonyl chloride, succinyl chloride, glutaryl chloride, adipoyl chloride, azelayl chloride, or sebacoyl chloride, the additive is N-sulphenyl aniline, and the organic phase solvent is one or more of n-hexane, cyclohexane, cyclopentane, n-heptane, n-octane, and isomeric alkanes.

[0011] 6. The method of claim 1, wherein the porous support membrane is a base membrane material selected from the group consisting of polysulfone, polyethersulfone, polyacrylonitrile, polyacrylonitrile after hydrolysis, and polyvinylidene fluoride.

[0012] The present application has the following advantages:

[0013] Based on the regulation of the interfacial polymerization process by the N-sulphenyl aniline additive, the present application solves the problem of poor permeability of conventional composite reverse osmosis membranes and obtains a reverse osmosis membrane with high permeation selectivity. The method is widely applicable and easy to scale up. Under certain optimal conditions, the permeability of the prepared reverse osmosis membrane is several times higher than that of the unmodified reverse osmosis membrane, while the separation selectivity is not sacrificed. Specific implementation method

[0014] The base membrane materials used are all commercial membranes.

[0015] Example 1

[0016] (1) 2.0 wt% of m-phenylenediamine / water solution was uniformly poured on the porous polysulfone support membrane, and deposited for 2 min, the excess solution was poured off, and the unbound aqueous monomer on the membrane surface was removed by using a wind knife;

[0017] (2) A solution containing 0.15 wt% of trimesoyl chloride and 0.00375 wt% of N-sulfenyl aniline in n-hexane was uniformly distributed on the surface of the membrane obtained in step (1), and after 60 s of reaction, the solution was poured off, and the membrane surface was washed with n-hexane;

[0018] (3) The membrane prepared in step (2) was placed in a 60 o C oven for 6 min to obtain a reverse osmosis membrane.

[0019] The membrane separation capacity test was carried out using a high-pressure flat membrane device at 25°C and 1.55 MPa, and the raw material liquid was a 2000 ppm NaCl solution. The reverse osmosis membrane prepared in this example had a sodium chloride rejection rate of more than 99%, a permeation flux of 58.3 L·m -2 ·h -1 ·MPa -1 , and a membrane surface water contact angle of 66.4°. The flux of the blank control membrane without the addition of N-sulfenyl aniline additive was only 25.0 L·m -2 ·h -1 ·MPa -1 , the sodium chloride rejection rate was 98%, and the membrane surface water contact angle was 79.2°.

[0020] Example 2

[0021] (1) 2.0 wt% of m-phenylenediamine / water solution was uniformly poured on the porous polysulfone support membrane, and deposited for 2 min, the excess solution was poured off, and the unbound aqueous monomer on the membrane surface was removed by using a wind knife;

[0022] (2) A solution containing 0.15 wt% of trimesoyl chloride and 0.0018 wt% of N-sulfenyl aniline in n-hexane was uniformly distributed on the surface of the membrane obtained in step (1), and after 60 s of reaction, the solution was poured off, and the membrane surface was washed with n-hexane;

[0023] (3) The membrane prepared in step (2) was placed in a 60 o C oven for 6 min to obtain a reverse osmosis membrane.

[0024] The membrane separation capacity test was carried out using a high-pressure flat membrane device at 25°C and 1.55 MPa, and the raw material liquid was a 2000 ppm NaCl solution. The reverse osmosis membrane prepared in this example had a sodium chloride rejection rate of more than 98%, a permeation flux of 57.5 L·m -2 ·h -1 ·MPa-1 The flux of the blank control film without the addition of N-sulfenyl aniline additive was only 25.0 L m -2 ·h -1 ·MPa -1 The rejection rate of sodium chloride was 98%, and the water contact angle on the surface of the membrane was 79.2°.

[0025] It can be seen that the permeation flux of the reverse osmosis membrane prepared based on the method is significantly improved.

[0026] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing a high-performance reverse osmosis membrane based on an N-sulfenyl aniline additive, comprising: using immersion or coating to make a water-phase monomer solution enter the pores of a porous support membrane, and then making it perform interfacial polymerization with an organic-phase solution containing an acid chloride monomer and an additive on the surface of the membrane to form a reverse osmosis membrane; the additive is an N-sulfenyl aniline, and the water-phase monomer is an aromatic amine.

2. The method for producing a reverse osmosis membrane according to claim 1, characterized by, After the interfacial polymerization forms a polyamide separation layer, the method further comprises the following steps: after washing the surface of the reverse osmosis membrane with an organic solvent for 10-100 s, drying the reverse osmosis membrane at a temperature of 25-95 ℃ for 30 s-10 min to obtain the reverse osmosis membrane.

3. The method of claim 1, wherein the reverse osmosis membrane is prepared by the steps of: The deposition time of the water-phase solution on the surface of the porous support membrane is 30 s-5 min, wherein the water-phase monomer is one or more of m-phenylenediamine, p-phenylenediamine, o-phenylenediamine, and diphenylamine.

4. The method of producing a reverse osmosis membrane according to claim 1, characterized by The organic-phase solution is composed of an acid chloride monomer, an additive, and an organic-phase solvent; wherein the mass fraction of the acid chloride monomer is 0.01-30 wt%, the concentration of the additive is 0.00001-5 wt%, and the mass fraction of the organic-phase solvent is 65-99.98999 wt%.

5. The method of claim 4, wherein the reverse osmosis membrane is prepared by the steps of: The acid chloride monomer is one or more of trimesoyl chloride, isophthaloyl chloride, terephthaloyl chloride, cyclohexanetricarboxylic acid chloride, 1,2,3,4-cyclobutane tetracarboxylic acid chloride, 1,2,4,5-cyclohexane tetracarboxylic acid chloride, oxalyl chloride, malonyl chloride, succinyl chloride, glutaroyl chloride, adipoyl chloride, azelaoyl chloride, and sebacoyl chloride; and the organic-phase solvent is one or more of n-hexane, cyclohexane, cyclopentane, n-heptane, n-octane, and isomeric alkanes. ​ 6. The method of claim 1, wherein the reverse osmosis membrane is prepared by The porous support membrane used is poly sulfone, poly ether sulfone, polyacrylonitrile, hydrolyzed polyacrylonitrile, or polyvinylidene fluoride.