Membrane distillation with electrospun omniphobic membrane for treatment of hypersaline chemical industry wastewater

Hypersaline chemical industry wastewater comprises various species with complex characteristics, challenging the proposal treatment of such wastewater. Membrane distillation (MD) is a promising technology to realize the zero liquid discharge treatment of wastewater, due to its high salt rejection and insensitivity to the feed concentration. However, the practical application of the MD process is hindered by membrane wetting and fouling issues. Herein, we developed an innovative strategy to fabricate a robust omniphobic membrane via bio-inspired silicification and fluorosilanization on an electrospun poly(vinylidene fluoride-co-hexafluoropropylene) nanofiber mat. The polydopamine/polyethylenimine (PDA/PEI) deposition time was optimized based on the results of membrane morphology, wettability, and pore structure measurements. The MD process achieved a stable flux using the omniphobic membrane even when treating feed solution containing sodium dodecyl sulfate (SDS). In addition, the omniphobic membrane significantly outperformed the pristine membrane in treating hypersaline chemical industry wastewater. This work provides a novel method for fabricating robust electrospun omniphobic membranes for high-performance treatment of hypersaline chemical industry wastewater via the MD process.