A preparation method of microporous membrane for membrane distillation with structure self-adjusting property

A technology of membrane distillation and microporous membrane, which is applied in chemical instruments and methods, pervaporation, membrane technology, etc., and can solve problems such as fixation

Active Publication Date: 2021-07-20
NINGBO UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In the current published literature, after the hydrophobic / hydrophilic composite membrane is prepared, the thickness of the hydrophobic layer and the thickness of the corresponding hydrophilic layer are fixed. There are no reports at home and abroad that the thickness of the hydrophobic layer can be automatically adjusted during the operation of the membrane distillation process.

Method used

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  • A preparation method of microporous membrane for membrane distillation with structure self-adjusting property
  • A preparation method of microporous membrane for membrane distillation with structure self-adjusting property

Examples

Experimental program
Comparison scheme
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Embodiment 1

[0023] Using N-isopropylacrylamide (NIPAAM) and polyethylene glycol methacrylate (MAPEG) as monomers, copolymerize to obtain a temperature-sensitive polymer with an LCST of 45°C - Poly(NIPAAM-MAPEG). Poly(NIPAAM-MAPEG) and polyvinylidene fluoride (PVDF) are blended, PVDF is 15% by mass percentage, Poly(NIPAAM-MAPEG) is 3.5%, and caprolactam is 81.5%, configures casting liquid, mixes Poly (NIPAAM-MAPEG) and PVDF were added to the molten diluent caprolactam, stirred and dissolved at a constant temperature of 140°C for 4 hours under the protection of nitrogen, and then left for defoaming under heat preservation to obtain a homogeneous casting solution. Pour it on a glass plate, scrape it into a nascent eco-film with a film scraper, put it in water, and solidify into a film through a phase separation process combining non-solvent-induced phase separation and thermal-induced phase separation. The solvent is completely dissolved, and then freeze-dried at -50°C to obtain a dry microp...

Embodiment 2

[0026] Using NIPAAM as a monomer, polymerize to obtain a temperature-sensitive polymer material with a LCST of about 31°C——Poly(NIPAAM). Blend Poly(NIPAAM) with PVDF, PVDF is 12% by mass, Poly(NIPAAM) is 2.4%, dimethylacetamide is 70.6%, polyethylene glycol-1000 is 15%, and cast film is configured solution, Poly(NIPAAM) and PVDF, porogen polyethylene glycol-1000 were added to the solvent dimethylacetamide, stirred and dissolved at a constant temperature of 80°C for 3 hours under the protection of nitrogen, kept for heat preservation and defoaming, and a homogeneous cast film was obtained liquid. Pour it on a glass plate, scrape it with a scraper to form a nascent film, put it in water, solidify into a film through a non-solvent-induced phase separation process, replace the water to completely dissolve the solvent in the film, and then freeze it at -50°C Dried to obtain a dry microporous membrane, the measured thickness of the dry membrane is 100 μm, the average pore diameter ...

Embodiment 3

[0029] Using NIPAAM and polyethylene glycol methacrylate (MAPEG) as monomers, adjust the ratio of monomers, and copolymerize to obtain a temperature-sensitive polymer with an LCST of 55°C—Poly(NIPAAM-MAPEG). Blend Poly(NIPAAM-MAPEG) with polyvinylidene fluoride-hexafluoropropylene, the content of polyvinylidene fluoride-hexafluoropropylene is 20% by mass, Poly(NIPAAM-MAPEG) is 5%, caprolactam is 75% , configure the casting solution, add Poly(NIPAAM-MAPEG) and polyvinylidene fluoride-hexafluoropropylene into the melted diluent caprolactam, stir and dissolve at a constant temperature of 150°C for 4 hours under the protection of nitrogen, keep warm and stand for defoaming, and obtain a homogeneous Casting solution. Pour it on a glass plate, scrape it into a nascent eco-film with a film scraper, put it in water, and solidify into a film through a phase separation process combining non-solvent-induced phase separation and thermal-induced phase separation. The solvent is completely...

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Abstract

The invention discloses a method for preparing a microporous membrane for membrane distillation with structural self-adjusting characteristics. The temperature-sensitive polymer material with the characteristic of hydrophilic / hydrophobic transition with temperature changes is blended with the polymer membrane material, and phase separation is adopted. The obtained microporous membrane is a double-layer membrane structure composed of a hydrophobic layer and a hydrophilic layer. The thickness of the hydrophobic layer and the hydrophilic layer can be automatically adjusted according to the operating temperature of the membrane distillation process. The microporous membrane for membrane distillation of the present invention has an automatically adjustable hydrophobic layer thickness compatible with the operating temperature, which greatly reduces the mass transfer resistance and improves the permeation flux of the membrane. At the same time, the correspondingly thickened hydrophilic layer can Significantly reduce the temperature polarization and the heat transfer loss of the entire membrane, effectively solve the contradiction between mass transfer and heat transfer in the current membrane distillation process, improve the characteristics and thermal efficiency of the membrane distillation process, and especially help to make full use of the waste heat of the lower temperature feed liquid for Concentration and separation of direct contact membrane distillation has a good application prospect.

Description

technical field [0001] The invention belongs to the technical field of polymer membrane separation, and in particular relates to a method for preparing a microporous membrane for membrane distillation with structure self-adjusting characteristics. Background technique [0002] Membrane distillation (MD) is a membrane process in which the volatile components in the mixed liquid are driven by the vapor pressure difference on both sides of the porous hydrophobic membrane to achieve mass transfer and separation. Liquid and low-temperature permeate are in direct contact, and steam passes through the membrane pores and condenses directly on the permeate side, which is the most studied membrane distillation process. [0003] The outstanding advantages of membrane distillation are: (1) cheap energy such as solar energy and industrial waste (waste) heat can be used, and the conventional distillation process can be realized without reaching the boiling point; (2) it can be operated un...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B01D67/00B01D71/34B01D61/36
CPCB01D61/364B01D67/0009B01D67/0011B01D67/0013B01D67/0016B01D71/34
Inventor 肖通虎殷凯陈祥颖
Owner NINGBO UNIV
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