Impact of pretreatment on the wetting resistance of hydrophobic PVDF membranes in vacuum membrane distillation
Hydrophilic leakage is one of the key bottlenecks faced by the application of hydrophobic membrane technology,mainly due to the wetting effect of surface active substances in pollutants in water on hydrophobic membranes.This article proposes a pre-treatment process using flocculation enhanced gas-liquid extraction to remove surface active substances from the original solution,in order to slow down the wetting process of hydrophobic membranes.This article uses sodium dodecylbenzenesulfonate to simulate negatively charged surface active substances such as humic acid in representative water bodies.A vacuum membrane distillation wetting experiment is conducted using a polyvinylidene fluoride hollow fiber hydrophobic membrane to explore the effects of pretreatment methods,the charge,type,and dosage of flocculants during the pretreatment process on the hydrophilic leakage of hydrophobic membrane materials.The results show that the pre-treatment process of flocculation enhanced gas-liquid extraction can effectively remove surface active substances from the raw material liquid;The pre-treatment effect of cationic flocculants is better than that of anionic flocculants;The pre-treatment effect of organic flocculants is better than that of inorganic flocculants;When the amount of cationic polyacrylamide added is 12 mg/L,the removal rate of the surfactant sodium dodecylbenzenesulfonate is 17％higher than that without flocculation pretreatment.
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万方数据
维普
