Method for preparing reverse osmosis composite membrane with high salt rejection rate and high flux by reforming polyamide separation layer

A technology of reverse osmosis composite membrane and rejection rate, which is applied in the field of preparation of liquid separation membranes. Significant increase in throughput, easy industrial scale-up, and simple preparation process

Pending Publication Date: 2022-02-25
TIANJIN UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

One is to influence the interfacial polymerization process by optimizing the interfacial polymerization process parameters, and then regulate the structure of the polyamide separation layer. This method is simple and easy to scale up, but the ability to improve the salt rejection rate and water flux of the membrane is limited.
The second is to introduce nanomaterials into the polyamide separation layer to build water mass transfer channels to improve membrane water flux, but this method is costly, complicated, and difficult for industrial scale-up
The third is to develop a new type of interfacial polymerized monomer and optimize the structure of the polyamide separation layer to increase the salt rejection rate and water flux of the membrane. This method has high research and development costs, long research and development cycles, and is difficult
The fourth is to develop a new process for preparing the polyamide separation layer. This method is usually difficult to change the structure of the separation layer essentially, so the ability to improve the salt rejection rate and water flux of the membrane is also limited.
The fifth is to dissolve the oligomers in the polyamide separation layer with an organic solvent. Although this method can effectively increase the water flux of the membrane, it usually reduces the salt rejection rate of the membrane, and the organic solvent used is usually flammable and explosive. Production There are certain safety hazards in the process
[0006] In short, the above methods are either unsatisfactory for membrane salt rejection and water flux improvement, or difficult for industrial scale-up

Method used

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  • Method for preparing reverse osmosis composite membrane with high salt rejection rate and high flux by reforming polyamide separation layer
  • Method for preparing reverse osmosis composite membrane with high salt rejection rate and high flux by reforming polyamide separation layer
  • Method for preparing reverse osmosis composite membrane with high salt rejection rate and high flux by reforming polyamide separation layer

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0023] (1) Prepare polyamide nascent membrane by interfacial polymerization: soak the polysulfone-based membrane in room temperature containing 3.0wt.% m-phenylenediamine, 2.6wt.% camphorsulfonic acid, 1.1wt.% triethylamine, 0.1 Wt.% Sodium dodecylsulfonate aqueous phase solution for 30s; use a rubber roller to remove the residual aqueous phase solution; Triformyl chloride was interfacially polymerized in n-heptane oil phase solution for 1 min, and then heat-treated in an oven at 80°C for 5 min and 30 s to prepare a nascent film.

[0024] (2) After soaking the nascent membrane in pure water for 10 minutes, soak the membrane in 5wt.% 4-dimethylaminopyridine modified aqueous solution to react for 5 seconds, pour off the remaining modified solution, and rinse the membrane surface repeatedly with pure water, Prepared modified polyamide reverse osmosis membrane.

[0025] Under the cross-flow test conditions of operating pressure 1.55MPa, test temperature 25°C, and test cross-flow ...

Embodiment 2

[0027] (1) The preparation of the primary film is the same as in Example 1.

[0028] (2) After soaking the nascent membrane in pure water for 1 min, soak the membrane in 2wt.% 4-dimethylaminopyridine modified aqueous solution to react for 1 min, pour off the remaining modified solution, and rinse the membrane surface repeatedly with pure water, Prepared modified polyamide reverse osmosis membrane.

[0029]Under the cross-flow test conditions of operating pressure 1.55MPa, test temperature 25°C and test cross-flow flow rate 1.5L / min, the rejection rate of the modified reverse osmosis membrane to 2000mg / L sodium chloride solution is 99.13%, and the flux is 61.65 L·m -2 h -1 .

Embodiment 3

[0031] (1) The preparation of the primary film is the same as in Example 1.

[0032] (2) After soaking the nascent film in pure water for 30 minutes, soak the film in an isoparaffin modification solution containing 5wt.% 4-dimethylaminopyridine to react for 3 minutes, pour off the remaining modification solution, and repeat with pure water The membrane surface is washed to prepare a modified polyamide reverse osmosis membrane.

[0033] Under the cross-flow test conditions of operating pressure 1.55MPa, test temperature 25°C, and test cross-flow flow rate 1.5L / min, the rejection rate of the modified reverse osmosis membrane to 2000mg / L sodium chloride solution is 99.33%, and the flux is 54.80 L·m -2 h -1 .

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Abstract

The invention relates to a method for preparing a reverse osmosis composite membrane with high salt rejection rate and high flux by reforming a polyamide separation layer. The method is characterized in that after interfacial polymerization membrane preparation, the membrane is soaked in a modified solution containing a nucleophilic catalyst to prepare the reverse osmosis composite membrane with high salt rejection rate and high flux. The mass percentage concentration of the nucleophilic catalyst in the modified solution is 0.01%-5%. The modified nucleophilic catalyst is prepared from 4-dimethylaminopyridine, 4-pyrrolidinyl pyridine and N-methylimidazole. The solvent comprises water, normal hexane and normal heptane. After modification, a sodium chloride solution with the concentration of 2000 mg / L is adopted for testing the salt rejection rate and the water flux of the membrane, and under the operation pressure of 15.5 bar, the water flux of the membrane is 38.46-84.90 L.m<-2>. h<-1>, and the salt rejection rate is 98.00-99.54%. The whole membrane preparation process is simple and easy to amplify.

Description

technical field [0001] The invention relates to a method of strengthening the nucleophilic reaction between the residual amine group and the acid chloride group in the polyamide layer through a nucleophilic catalyst, and reforming the structure of the separation layer of the reverse osmosis composite membrane with polyamide as the separation layer material to prepare a The invention relates to a reverse osmosis membrane method with high sodium chloride rejection rate and high flux, belonging to the field of liquid separation membrane preparation. Background technique [0002] Reverse osmosis membrane technology has a wide range of applications in seawater desalination, wastewater treatment, antibiotic concentration and other fields. Membrane technology is of great value in alleviating the shortage of fresh water resources because of its environmental friendliness, easy operation, easy scale-up, low energy consumption, and small device footprint. Reverse osmosis membrane is ...

Claims

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Application Information

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IPC IPC(8): B01D67/00B01D69/12B01D71/56
CPCB01D67/0006B01D69/125B01D69/12B01D71/56Y02A20/131
Inventor 王志吴浩文刘莹莹王宠李旭王纪孝
Owner TIANJIN UNIV
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