Study on the preparation of PVDF porous membranes by vapor-induced phase separation and its membrane distillation performance
Preparing membranes with excellent anti-wetting properties for membrane distillation(MD)is a challenge in the field of membrane separation.This article uses polyvinylidene fluoride(PVDF)as the membrane material,N,N-dimethylformamide(DMF)as the solvent,and 1,2-propanediol as the additive to prepare highly hydrophobic PVDF porous membranes through vapor-induced phase separation(VIPS)method.The effects of process parameters such as exposure time,relative humidity(RH),and vapor temperature on the structure and performance of PVDF porous membranes were studied.The results showed that when the exposure time,relative humidity,and vapor temperature of the VIPS process were 1 minute,85％,and 60 ℃,respectively,the surface of the as-prepared PVDF porous membrane exhibited a micro/nano hierarchical structure,with a water contact angle of 141° and a porosity of about 78％.In the DCMD experiment using high salinity water containing surfactants as the feed solution,our membrane exhibited a stable water flux of 20 L/(m2·h)and a salt rejection rate of almost 100％.
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