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Film casting liquid for PVDF flat membrane and preparing method for PVDF flat membrane

A technology of casting liquid and flat film, applied in the field of water treatment, can solve the problems of low surface strength, scratched hard particles, easy to be scratched, etc., and achieve the effect of high surface strength

Inactive Publication Date: 2015-10-21
黄义忠
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The flat film with such a structure is very easy to be scratched due to its thin skin
[0008] Most of the plate membranes currently available on the market are manufactured by the NIPS method, and the surface strength is relatively low. It is very easy to be scratched by hard particles that may exist in the wastewater during operation, and may also be scratched by the operator during installation or maintenance. accidentally damaged

Method used

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  • Film casting liquid for PVDF flat membrane and preparing method for PVDF flat membrane
  • Film casting liquid for PVDF flat membrane and preparing method for PVDF flat membrane
  • Film casting liquid for PVDF flat membrane and preparing method for PVDF flat membrane

Examples

Experimental program
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Effect test

Embodiment 1

[0030] PVDF resin: solvent: pore-forming agent: additive is 20:35:40:5, stirred and mixed at 110 degrees Celsius to form a uniform casting solution, in which the solvent is dimethylacetamide, and the pore-forming agent is diethylene diacetate Alcohol monomethyl ether, the additive is a mixture of polyethylene glycol and polyvinylpyrrolidone with a weight ratio of 2:3.

[0031] Cool the casting solution to 80 degrees and degas for 6 hours, scrape it evenly on the PET non-woven fabric, and cool it at room temperature for 2 minutes, so that the surface temperature of the casting solution is less than 40 degrees, then put it in distilled water and wash it for 10 minutes before taking it out The temperature of the distilled water is 29 degrees Celsius, the pore diameter of the flat membrane is measured to be 0.03 micron, and the pure water flux under 1BAR pressure is 800LMH. After being rinsed with pure water for 60 minutes under 6BAR, the surface of the membrane was as good as new...

Embodiment 2

[0033] PVDF resin: solvent: pore forming agent: additive is 18:42:35:5, stirred and mixed at 100 degrees Celsius to form a uniform casting solution, in which the solvent is dimethylacetamide and dimethylformamide by weight The mixture with a ratio of 22:20, the pore forming agent is a mixture of diethylene glycol monomethyl ether and ethylene glycol monomethyl ether with a weight ratio of 20:15, and the additive is polyethylene glycol and polyvinylpyrrolidone with a weight ratio of 1:4 mixture.

[0034] Cool the casting solution to 60 degrees and degas it for 6 hours, scrape it evenly on the PET non-woven fabric, and cool it at room temperature for 2 minutes to make its surface temperature less than 30 degrees Celsius, then put it in distilled water and wash it for 10 minutes before taking it out. A PVDF flat membrane with uniform surface was obtained, the temperature of distilled water was 19 degrees Celsius, the pore diameter of the flat membrane was determined to be 0.05 mi...

Embodiment 3

[0036]PVDF resin: solvent: pore-forming agent: the ratio of additives is 8:45:45:2, stir and mix at 80 degrees Celsius to form a uniform casting solution, in which the solvent is dimethylformamide, and the pore-forming agent is ethylene glycol Alcohol monomethyl ether, the additive is polyethylene glycol.

[0037] Cool the casting solution to 40 degrees and degas it for 6 hours, scrape it evenly on the PET non-woven fabric, cool it at room temperature for 2 minutes, so that its surface temperature is less than 20 degrees Celsius, then put it in distilled water and wash it for 10 minutes before taking it out. Obtain a PVDF flat membrane with a uniform surface, the temperature of distilled water is 9 degrees Celsius, the pore diameter of the flat membrane is measured to be 0.1 micron, and the pure water flux under 1BAR pressure is 4000LMH. After being rinsed with pure water for 60 minutes under 6BAR, the surface of the membrane was as good as new without any damage, showing very...

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Abstract

The invention provides film casting liquid for a PVDF flat membrane and a preparing method for the PVDF flat membrane. The obtained PVDF flat membrane is high in surface strength and high in flux. The film casting liquid comprises, by weight, 8-28 parts of PVDF resin, 20-50 parts of solvent, 20-50 parts of pore-forming agent and 1-5 parts of additive. The solvent is dimethylformamide, dimethylacetamide and dimethyl sulfoxide. The pore-forming agent is ethylene glycol monomethyl ether and diethylene glycol monomethyl ether. The additive is polyvinylpyrrolidone and polyethylene glycol. The film casting liquid is cooled to 40-80 DEG C, the temperature is maintained for degassing for 4-6 hours, then the film casting liquid is evenly scraped on PET non-woven fabric through a film scraping machine and stayed in air for 1-2 minutes, the temperature of the surface of the film casting liquid is controlled to be lower than 40 DEG C, distilled water serves as gelling and cleaning liquid, after gelling and cleaning are conducted in the gelling and cleaning liquid for 5-10 minutes, the PET non-woven fabric is taken out, the PVDF flat membrane is obtained after the film is separated from the PET non-woven fabric, and the temperature of the distilled water is lower than the temperature of the surface of the film casting liquid by at least 10 DEG C.

Description

technical field [0001] The invention relates to the technical field of water treatment, in particular to a casting liquid of a PVDF flat membrane and a preparation method of the PVDF flat membrane. Background technique [0002] Membrane bioreactor (hereinafter referred to as MBR) replaces the traditional secondary sedimentation tank with membrane separation technology, and filters the biochemical sewage out of the bioreactor to obtain treated water with very low turbidity. At the same time, the sludge, bacteria and macromolecular organic matter in the system are still kept in the reactor. This separation method improves the effluent water quality, increases the sludge concentration in the reactor, and retains beneficial microorganisms. Compared with the traditional activated sludge method, the effluent water quality of the MBR technology is good, and the COD, BOD, and turbidity are very low. Most of the bacteria and viruses are intercepted, and the quality of the effluent w...

Claims

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Application Information

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IPC IPC(8): B01D69/06B01D71/34B01D67/00C02F3/10C02F1/44
CPCY02W10/10
Inventor 黄义忠
Owner 黄义忠
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