A method for preparing superhydrophobic microporous membranes by synergistically regulating phase separation with aqueous inorganic salt solution

Abstract

The invention discloses a method for preparing a super-hydrophobic microporous membrane by synergistically regulating phase separation with an aqueous inorganic salt solution. In the casting liquid system composed of polymer / solvent / additive, weak non-solvent is beneficial to polymer crystallization, strong non-solvent is conducive to rapid gelation and the formation of large cavities, and inorganic salt grains nucleate and cause pores By using the advantages of the three agents, they play a synergistic role in the liquid phase separation process of the cast membrane, and prepare a homogeneous superhydrophobic microsphere structure membrane with good pore connectivity. The surface of the microsphere structure has a nano-scale papillae structure when the polymer is solidified, thereby forming a super-hydrophobic micro-nano structure on the surface of the membrane like a lotus leaf. The membrane body is completely composed of a microsphere structure, and the membrane pores have good connectivity. and hydrophobicity, thereby improving the stability and durability of the hydrophobic microporous membrane.

Description

technical field [0001] The invention belongs to the field of membrane separation, and relates to a method for preparing a super-hydrophobic microporous membrane, in particular to a method for introducing an aqueous solution of inorganic salt into a membrane casting liquid, and then synergistically regulating phase separation to prepare a super-hydrophobic microporous membrane. Background technique [0002] In recent years, membrane separation technology has been highly valued by many countries in the world. Membrane distillation (MD for short) is a membrane separation process that uses a hydrophobic microporous membrane and uses the vapor pressure difference on both sides of the membrane as the driving force for mass transfer. MD has gradually become a new type of membrane separation technology widely used due to its advantages such as high interception efficiency, direct access to ultrapure water, mild operating conditions, and ability to handle high-concentration raw mater...

AI Technical Summary

Problems solved by technology

By controlling the preparation conditions and adjusting the surface roughness of the membrane, superhydrophobic membranes can be obtained, but high voltage and expensive equipment are required, which limits its application in industry

(2) The spraying method sprays low surface energy substances or a coating solution containing hydrophobic nanoparticles on the surface of the membrane, but the coating and the membrane matrix have poor adhesion, and it is easy to fall off during long-term operation, and the coating will increase. Resistance to water vapor penetration, reducing flux

(3) The plasma surface modification technology is to etch the surface of the material by physical or chemical methods to obtain a rough structure, thereby preparing a super-hydrophobic film, but it requires high equipment and operating conditions and is not suitable for mass production

[0007] At present, there is no research report that the use of weak non-solvent is beneficial to crystallization, strong non-solvent is beneficial to gelation and large cavity formation, and the role of crystal nuclei and porogens of inorganic salt grains, using the three in the casting film liquid phase The synergistic effect in the separation process makes the polymer aggregate and gel quickly, resulting in a superhydrophobic membrane with good pore connectivity

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