Dual-Nozzle Electrospinning for Janus Membranes in Membrane Distillation of Highly Saline and Oil-Contaminated Waters

Electrospun nanofibrous membranes are highly valued for membrane distillation (MD) due to their inherent porosity and tunable structure. This study introduces a novel dual-nozzle electrospinning method to fabricate a multilayered Janus membrane, combining an omniphobic layer of PVDF fibers and fluorinated TiO₂-PVDF microclusters with a hydrophilic layer of hydrolyzed PMA fibers. The resulting membrane demonstrated exceptional performance and durability. In a 21 h MD operation against oily saline solutions, it retained 80% of its initial flux while producing high-purity water (conductivity <5 μS/cm). Notably, the membrane exhibited complete underwater oil repellence, preventing fouling from oil droplet adhesion. Furthermore, in a 7 h test with highly saline feed, the membrane maintained 99% of its initial flux and permeate conductivity below 60 μS/cm. The success of the membrane is attributed to the dual-nozzle setup, which provides both improved processing efficiency and strong interlayer adhesion, enhancing structural integrity during prolonged MD operations and cleaning cycles. This work presents a robust and scalable method for fabricating high-performance Janus membranes, offering a significant advancement for treating challenging, oil-contaminated water via membrane distillation.