COF thin membrane material for membrane distillation seawater desalination and preparation method of COF thin membrane material

Abstract

The invention relates to a COF thin membrane material for membrane distillation seawater desalination. Hydrophilic and hydrophobic pore channels which are different in size and change along with a depth gradient environment are formed in a COF thin membrane; the COF thin membrane is used for membrane distillation seawater desalination, and has the following characteristics that the membrane distillation flux and retention rate performance are excellent: the hydrophobic pore channels only allow water vapor to pass through and prevents liquid from passing through, and the theoretical retention rate reaches 100%; the material has the characteristic of high porosity, so that water vapor has more mass transfer channels in unit area; the crystallinity and the orientation are good, and the mass transfer resistance of the water vapor in regular through pore channels perpendicular to a substrate is low, so that the flux is improved; the thickness is nanoscale, so that the mass transfer distance of water vapor is greatly shortened, and the flux is improved.

Description

technical field [0001] The invention belongs to the field of seawater desalination, in particular to the field of membrane distillation seawater desalination. Background technique [0002] Membrane distillation (MD for short) is a new separation technology combining traditional distillation process and membrane separation technology. It uses the vapor pressure difference on both sides of the hydrophobic microporous membrane as the driving force for mass transfer. The feed liquid at a certain temperature contacts the membrane. Due to the hydrophobicity of the membrane, the feed liquid cannot pass through the membrane pores, but the moisture in the feed liquid at the membrane pores It can be vaporized and pass through the membrane hole in the form of water vapor to reach the other side of the membrane, while other non-volatile components in the feed liquid are trapped to achieve the purpose of separation. According to the form, membrane distillation can be divided into direct...

AI Technical Summary

Problems solved by technology

However, the traditional polymers commonly used in membrane distillation have problems such as low flux, poor long-term cycle stability, membrane fouling and membrane infiltration, which have always limited the development of this technology.

Researchers usually need to modify the surface of the hydrophobic membrane to be hydrophilic to enhance the anti-fouling performance, but the modification process is complicated and additionally increases the mass transfer resistance, which further reduces the flux

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