Preparation method of reverse osmosis membrane based on N-sulfinyl aniline additive

Abstract

The invention provides a method for preparing a high-performance reverse osmosis membrane based on an N-sulfinyl aniline additive. According to the preparation method, N-sulfinyl aniline is introduced as an organic phase additive under traditional reverse osmosis membrane preparation conditions, a polyamide separation layer is prepared on a polysulfone base membrane by regulating interfacial polymerization, and the high-performance reverse osmosis membrane is obtained. The additive provided by the invention can effectively reduce the thickness of the membrane and improve the crosslinking degree and hydrophilicity. Compared with a traditional polyamide reverse osmosis membrane, the permeation flux of the modified membrane can reach 58.3 L.m <-2 >. H <-1 >. MPa <-1 >, the rejection rate of sodium chloride reaches 99.23%, and higher water flux and excellent desalting performance are shown. The method is simple to operate and low in cost, and provides a new thought and technical approach for preparing the high-performance polyamide reverse osmosis membrane.

Description

Technical Field

[0001] The invention relates to a method for preparing a high-permeability reverse osmosis membrane, which is suitable for the fields of brackish water desalination, seawater desalination, wastewater treatment, etc. Background Art

[0002] Due to the rapid development of social economy, the demand for fresh water resources has increased significantly. Currently, many regions in the world are facing the problem of water shortage. Membrane separation technology has been widely used in brackish water desalination, seawater desalination, wastewater treatment and other fields due to its advantages of high separation efficiency, low cost, low energy consumption, simple operation, safety and stability. However, the traditional composite reverse osmosis membrane prepared by interfacial polymerization is subject to the "trade-off" effect between permeation flux and selectivity, and has gradually failed to meet people's needs. How to increase the permeation flux of water without sacrificing salt retention has become the key idea to solve the problem.

[0003] Adding additives is an important method to improve membrane performance. The introduction of additives can increase the interfacial polymerization rate, reduce the thickness and resistance of the separation layer, or make the membrane surface looser (larger free volume) and rougher (specific surface area), thereby increasing the flux of the composite membrane. However, most of the additives introduced into reverse osmosis membranes at this stage are nanoparticle additives. Although they can effectively improve the performance of reverse osmosis membranes, the synthesis and application processes are relatively complicated, and the aggregation of nanoparticles will form defects in the reverse osmosis membrane, thereby reducing the separation selectivity of the membrane. Therefore, if you want to further improve the operating efficiency of the reverse osmosis membrane and reduce the operating cost, you can choose a simple method to introduce small molecule additives into the reverse osmosis membrane, thereby obtaining certain economic benefits and social value. Summary of the invention

[0004] The purpose of the present invention is to introduce small molecule N-sulfenylanilide as an additive into the organic phase to regulate the interfacial polymerization process, thereby obtaining a high-performance reverse osmosis membrane. The method has a wide range of applications and is easy to scale up, making up for the shortcomings of the prior art.

[0005] The technical solution of the present invention is summarized as follows:

[0006] 1. A method for preparing a high-performance reverse osmosis membrane based on N-sulfenylanilide additives, comprising allowing an aqueous monomer solution to enter the pores of a porous support membrane by immersion, coating or unsupported means, and then subjecting it to an interfacial polymerization reaction with an organic phase solution containing an acyl chloride monomer and an additive on the surface of the membrane to form a reverse osmosis membrane.

[0007] 2. The method for preparing a reverse osmosis membrane according to claim 1 is characterized in that, after the interfacial polymerization forms the 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 seconds, drying the reverse osmosis membrane at a temperature of 25-95° C. for 30 seconds to 10 minutes to obtain a reverse osmosis membrane.

[0008] 3. The method for preparing a reverse osmosis membrane according to claim 1 is characterized in that the deposition time of the aqueous solution on the surface of the porous support membrane is 30s-5min, wherein the aqueous monomer is one or more aromatic amines such as m-phenylenediamine, p-phenylenediamine, o-phenylenediamine, and benzidine.

[0009] 4. The method for preparing a reverse osmosis membrane according to claim 1 is characterized in that the organic phase solution consists of an acyl chloride monomer, an additive and an organic phase solvent; wherein the mass fraction of the acyl chloride monomer is 0.01-30wt%, the concentration of the additive is 0.00001-5wt%, and the mass fraction of the organic phase solvent is 65-99.98999wt%.

[0010] 5. The method for preparing a reverse osmosis membrane according to claim 4, characterized in that the acyl chloride monomer is one or more of trimesoyl chloride, isophthaloyl chloride, terephthaloyl chloride, cyclohexanetrichloride, 1,2,3,4-cyclobutanetetracarboxylic acid chloride, 1,2,4,5-cyclohexanetetracarboxylic acid chloride, oxalyl chloride, malonyl chloride, succinyl chloride, glutaryl chloride, adipic chloride, azelaic chloride, and sebacoyl chloride. The additive is N-sulfenylanilide. The organic phase solvent is one or more of n-hexane, cyclohexane, cyclopentane, n-heptane, n-octane, and isoparaffin.

[0011] 6. The method for preparing a reverse osmosis membrane according to claim 1, wherein the porous support membrane used is a base membrane material such as polysulfone, polyethersulfone, polyacrylonitrile, hydrolyzed polyacrylonitrile, polyvinylidene fluoride, etc.

[0012] The present invention has the following excellent effects:

[0013] Based on the regulation of the interfacial polymerization process by N-sulfenylanilide additives, the present invention solves the problem of poor permeability of common composite reverse osmosis membranes and obtains reverse osmosis membranes with high permeability selectivity. The method has a wide range of applications and is easy to scale up. Under certain optimal conditions, the permeability of the prepared reverse osmosis membrane is improved several times compared with that of the unmodified reverse osmosis membrane, while not sacrificing its separation selectivity. Specific implementation methods

[0015] The base film materials used are all commercial films.

[0016] Implementation Example 1

[0017] (1) Pour a 2.0 wt% m-phenylenediamine / water solution evenly onto a polysulfone porous support membrane and allow to settle for 2 min, then pour off the excess solution and use an air knife to remove unbound aqueous monomers on the membrane surface;

[0018] (2) uniformly distributing a n-hexane solution containing 0.15 wt % of trimesoyl chloride and 0.00375 wt % of N-sulfenylanilide on the surface of the membrane obtained in step (1), discarding the solution after reacting for 60 s, and washing the membrane surface with n-hexane;

[0019] (3) The membrane prepared in step (2) was placed in an oven at 60° C. for 6 min to obtain a reverse osmosis membrane.

[0020] The membrane separation capacity was tested using a high-pressure flat membrane device at 25°C and 1.55 MPa. The raw material liquid was a 2000 ppm NaCl solution. The sodium chloride rejection rate of the reverse osmosis membrane prepared in this example exceeded 99%, and the permeation flux was 58.3 L·m -2 ·h -1 MPa -1 The water contact angle of the membrane surface was 66.4°. The flux of the blank control membrane without N-sulfenylanilide additive was only 25.0 L·m -2 ·h -1 MPa -1 The retention rate of sodium chloride is 98%, and the water contact angle on the membrane surface is 79.2°.

[0021] Implementation Example 2

[0022] (1) Pour a 2.0 wt% m-phenylenediamine / water solution evenly onto a polysulfone porous support membrane and allow to settle for 2 min, then pour off the excess solution and use an air knife to remove unbound aqueous monomers on the membrane surface;

[0023] (2) uniformly distributing a n-hexane solution containing 0.15 wt % of trimesoyl chloride and 0.0018 wt % of N-sulfenylanilide on the surface of the membrane obtained in step (1), discarding the solution after reacting for 60 s, and washing the membrane surface with n-hexane;

[0024] (3) The membrane prepared in step (2) was placed in an oven at 60° C. for 6 min to obtain a reverse osmosis membrane.

[0025] The membrane separation capacity was tested using a high-pressure flat membrane device at 25°C and 1.55 MPa. The raw material liquid was a 2000 ppm NaCl solution. The sodium chloride rejection rate of the reverse osmosis membrane prepared in this example exceeded 98%, and the permeation flux was 57.5 L·m -2 ·h -1 MPa -1The water contact angle of the membrane surface was 68.6°. The flux of the blank control membrane without N-sulfenylanilide additive was only 25.0 L·m -2 ·h -1 MPa -1 The retention rate of sodium chloride is 98%, and the water contact angle on the membrane surface is 79.2°.

[0026] It can be seen that the permeation flux of the reverse osmosis membrane prepared based on this method has been significantly improved.

[0027] 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 a high-performance reverse osmosis membrane based on N-sulfenylanilide additives, comprising allowing an aqueous monomer solution to enter the pores of a porous support membrane by immersion, coating or unsupported means, and then subjecting it to an interfacial polymerization reaction with an organic phase solution containing an acyl chloride monomer and an additive on the surface of the membrane to form a reverse osmosis membrane.

2. The method for preparing a reverse osmosis membrane according to claim 1, wherein: After the polyamide separation layer is formed by interfacial polymerization, the method further comprises the following steps: washing the surface of the reverse osmosis membrane with an organic solvent for 10-100 seconds, and then drying the reverse osmosis membrane at a temperature of 25-95° C. for 30 seconds to 10 minutes to obtain a reverse osmosis membrane.

3. The method for preparing a reverse osmosis membrane according to claim 1, wherein: The aqueous solution is deposited on the surface of the porous support membrane for 30s-5min, wherein the aqueous monomer is one or more aromatic amines such as m-phenylenediamine, p-phenylenediamine, o-phenylenediamine, and benzidine.

4. The method for preparing a reverse osmosis membrane according to claim 1, characterized in that The organic phase solution consists of acyl chloride monomer, additive and organic phase solvent; wherein the mass fraction of acyl chloride monomer is 0.01-30wt%, the concentration of additive is 0.00001-5wt%, and the mass fraction of organic phase solvent is 65-99.98999wt%.

5. The method for preparing a reverse osmosis membrane according to claim 4, wherein The acyl chloride monomer is one or more of trimesoyl chloride, isophthaloyl chloride, terephthaloyl chloride, cyclohexanetrichloride, 1,2,3,4-cyclobutanetetracarboxylic acid chloride, 1,2,4,5-cyclohexanetetracarboxylic acid chloride, oxalyl chloride, malonyl chloride, succinyl chloride, glutaryl chloride, adipoyl chloride, azelayl chloride, and sebacoyl chloride. The additive is N-sulfenylanilide. The organic phase solvent is one or more of n-hexane, cyclohexane, cyclopentane, n-heptane, n-octane and isoparaffin.

6. The method for preparing a reverse osmosis membrane according to claim 1, wherein The porous support membrane used is a base membrane material such as polysulfone, polyethersulfone, polyacrylonitrile, polyacrylonitrile after hydrolysis, and polyvinylidene fluoride.