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High-throughput polyimide nano-filtration membrane preparation method

A polyimide nano and nanofiltration membrane technology, applied in chemical instruments and methods, membrane technology, semi-permeable membrane separation, etc., can solve problems such as low flux

Active Publication Date: 2015-08-05
BEIJING UNIV OF CHEM TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

But generally speaking, its flux is low, generally 10L / m 2 h, how to effectively improve the separation efficiency of PI nanofiltration membranes has become the focus of researchers

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0019] 1) Dissolve 11.8962g of dried 4,4'-diaminodiphenylmethane (MDA) in 141.57g of N-methylpyrrolidone (NMP), and add 13.3489g of dried pyromellitic acid di anhydride (PMDA), stirred and reacted for 6 hours to obtain a polyamic acid solution with a concentration of 15% by mass. The following concentrations are mass percentage concentrations unless otherwise specified

[0020] 2) After the polyamic acid solution is filtered through a 200-mesh screen, the filtrate is allowed to stand for degassing for 24 hours. At room temperature, the polyamic acid solution is evenly coated on a clean glass plate with a scraper. It is about 100-150 μm, and then immediately transferred to a refrigerator at 0°C for 8 hours of low-temperature gel treatment.

[0021] 3) soak the polyamic acid membrane after the gel obtained in step 2) in ethanol and solidify to obtain a polyamic acid nanofiltration membrane, then soak the polyamic acid nanofiltration membrane in pure water for 8 hours, freeze-dr...

Embodiment 2

[0025] 1) Dissolve 11.8962g of dried 4,4'-diaminodiphenylmethane (MDA) in 59.82g of N,N-dimethylacetamide (DMAc), and add 13.7416g of dried Pyromellitic dianhydride (PMDA), stirred and reacted for 8 hours to obtain a polyamic acid solution with a concentration of 30%.

[0026] 2) After the polyamic acid solution is filtered through a 200-mesh screen, the filtrate is allowed to stand for degassing for 24 hours. At room temperature, the polyamic acid solution is evenly coated on a clean glass plate with a scraper. 100-150 μm, and then immediately transferred to a refrigerator at 5°C for low-temperature gel treatment for 18 hours.

[0027] 3) immerse the polyamic acid membrane after the gel obtained in step 2) into pure water to solidify to obtain a polyamic acid nanofiltration membrane, then soak the polyamic acid nanofiltration membrane in pure water for 8 hours, freeze-dry for 18 Hour, obtain the dry polyamic acid nanofiltration membrane.

[0028] 4) Place the dried polyamic...

Embodiment 3

[0031] 1) Dissolve 15.0156g of dried 4,4'-diaminodiphenylmethane (MDI) in 446.43g of dimethylsulfoxide (DMSO), and add 13.4798g of dried pyromellitic acid under nitrogen protection Dianhydride (PMDA), stirred and reacted for 7 hours to obtain a polyamic acid solution with a concentration of 6%.

[0032] 2) After filtering the polyamic acid solution through a 200-mesh screen, let the filtrate stand for degassing for 24 hours. -150 μm, and then immediately transferred to a refrigerator at 1°C for 8 hours of low-temperature gel treatment.

[0033] 3) The polyamic acid membrane after the gel obtained in step 2) is immersed in methanol to solidify to obtain a polyamic acid nanofiltration membrane, and then the polyamic acid nanofiltration membrane is soaked in pure water for 12 hours, and freeze-dried for 24 hours , to obtain a dry polyamic acid nanofiltration membrane.

[0034] 4) Place the dried polyamic acid film in a vacuum drying oven and heat it up to 100°C at a heating rat...

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PUM

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Abstract

The invention relates to a high-throughput polyimide nano-filtration membrane preparation method, and belongs to the technical field of organic membrane separation. The preparation method comprises: preparing a polyamide acid solution, coating the polyamide acid solution into a membrane, further treating under a specified condition by using the crystallization characteristic of the polyamide acid so as to make the polyamide acid be subjected to complete crystallization and gelation, carrying out solid phase separation to obtain a polyamide acid nano-filtration membrane with characteristics of loose skin and high porosity, and finally adopting a thermal imidization method to convert the polyamide acid into polyimide so as to prepare the novel polyimide nano-filtration membrane having the gel-like structure. According to the present invention, the prepared membrane has characteristics of high strength and solvent resistance; with the gel characteristic, the asymmetric finger-like pore structure of the traditional nano-filtration membrane is changed to obtain the spongy-like cluster hole, such that the skin thickness of the skin layer is reduced, and the porosity is substantially increased; and the prepared polyimide nano-filtration membrane can be used for organic solvent systems such as nano-filtration separation of small molecule organic dyes, and further has characteristics of high throughput and high rejection rate.

Description

technical field [0001] The invention belongs to the technical field of organic membrane separation, and in particular relates to a preparation method of a high-throughput polyimide nanofiltration membrane used for the purification, concentration and desalination of organic solvent system substances. Background technique [0002] Nanofiltration membranes can be divided into asymmetric membranes and composite membranes in form. The asymmetric membrane is composed of a thin dense cortex and a subcortical porous support sublayer in terms of cross-sectional morphology, presenting an asymmetric structure. The separation performance and mass transfer resistance of the membrane are mainly controlled by the very thin skin layer, and the porous sublayer mainly plays the role of support and reinforcement. [0003] The phase inversion method is the main method for preparing asymmetric structure nanofiltration membranes by using polymers. Among many polymer materials, polyimide (PI) has ...

Claims

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Application Information

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IPC IPC(8): C08J5/18C08L79/08C08K3/36C08K3/22C08G73/10B01D71/64B01D67/00B01D61/02
Inventor 潘凯曹兵胥建美罗超
Owner BEIJING UNIV OF CHEM TECH