Incorporating amphiphilic modifier into PVDF membrane through in-situ electrostatic crosslinking for efficient oil-water separation

Abstract

Constructing stable amphiphilic membrane surfaces in a facile and controlled way is highly desired for fabrication of antifouling water purification membranes. Herein, inspired by adhesives of sandcastle worms, we proposed an in-situ electrostatic crosslinking method to incorporate amphiphilic modifiers into poly (vinylidene fluoride) membranes. Pluronic F127 grafted with positively charged quaternary ammonium groups are added into the casting solution , while perfluorosulfonic acid bearing negatively charged sulfonic acid groups and perfluorocarbon chains are dissolved in the coagulation bath . During non-solvent induced phase separation process, electrostatic crosslinking between quaternary ammonium and sulfonic acid led to the in-situ formation of amphiphilic modifiers on membrane surfaces and pore walls. The resulting membrane exhibits high water permeance up to 625 Lm −2 h −1 bar −1 and superior antifouling performance with total flux decline ratio of 2 % and flux recovery ratio of 99.3 % for oil-water separation. Besides, the membrane displays excellent structural stability and self-cleaning properties against highly viscous crude oils.