Reinforced PS-PVDF-WO3 superhydrophobic antiwetting membrane for membrane distillation

Abstract

Membrane distillation (MD) is an energy-efficient desalination process with abilities to achieve nearly zero liquid discharge and recovery of resources. Nevertheless, MD's transition from laboratory to industrial scale has been largely challenged by expensive and complex fabrication methods for hydrophobic membranes, as well as lack of resistance against wetting and scaling. Present study demonstrates about the development of a hydrophobic electrospun membrane using a low-cost polystyrene (~1.057 $ per kg) polymer blended with PVDF (~80 $ per kg), followed by the surface modification via electrospraying of silane functionalized tungsten trioxide (WO3) nanoparticles. The characteristics of the fabricated membrane in terms of deionized water contact angle revealed ultra-high surface contact angle (~172°) and low sliding angle (<5°). The low thermal conductivity (~0.166 W/mK) of electrospun membrane accredited decreases in temperature polarization during MD operation, resulting in enhanced transportation of water vapors from feed to permeate side. Furthermore, the electrospun membrane attained resilience against wetting, along with stable permeate flux (~25 LMH) and high salt rejection (>99.9 %) with low surface tension (~28 mN/m) saline feed. Tensile tests (firm up to 45 N) and harsh chemical exposure (durable at pH 2 and pH 12) confirmed the structural robustness of the fabricated membrane.