Unravelling the effect of ZnO nanoparticles deposition via dip coating to enhance performance of PVDF-based omniphobic membrane for membrane distillation

Abstract

Membrane wetting is one of the main obstacles that inhibits a membranes’ performance for membrane distillation. The aim of this research is to examine the effect of ZnO Nps re-entrant structure loading on polyvinylidene fluoride (PVDF) membrane surface for seawater desalination via direct contact membrane distillation. The deposition of ZnO Nps onto the PVDF hollow fiber membrane surface via dip-coating and followed by membrane fluorination using fluoroalkylsilane. During the dip-coating process, ZnO Nps were varied at different concentrations, ranging from 1, 2, and 3 wt%. The results showed that the surface morphology of the omniphobic membrane which exhibited a higher concentration of ZnO Nps led to an improvement in the contact angle values for all tested liquids. Furthermore, it also led to the improvement of the membrane surface roughness and liquid entry pressure (LEP) of the omniphobic membrane. The desalination performance of the FAS-P-3WT%-T membrane in the presence of humic acid as a foulant exhibited an excellent water flux value of around ∼6 L/m²h coupled with an outstanding salt rejection performance close to 100 %. The higher loading of ZnO Nps as a re-entrant structure can significantly improve the anti-wetting properties as well as performance of PVDF-based membrane.