Demulsification performance of superhydrophobic PVDF membrane: A parametric study

Oil-water separation using hierarchical-structured superhydrophobic and superoleophilic membranes have been recently received remarkable attention. In this study, a polyvinylidene difluoride (PVDF) based membrane was prepared by a non-solvent induced phase inversion method for oil-water emulsions separation. The influences of the two key parameters, namely the concentration of emulsifying agent and water content of the feed emulsion, on the membrane performance were investigated in terms of the permeate flux and water rejection. Span-80, distilled water and n-heptane were employed as an emulsifying agent, dispersed phase and continuous phase, respectively. Results showed that an increase in the emulsifier concentration led to a decrease in the oil permeate flux and water rejection. The emulsifier concentration had the most significant effect on the oil-water separation compared with the water content in the feed emulsion. In a continuous experiment lasted for 120 h, more than 95% water rejection was maintained but with a significant drop in oil flux. The well-structured superhydrophobic PVDF membrane showed promise for water-in-oil emulsion separations.