Recent Progress in Electrospun Nanofibers for the Membrane Distillation of Hypersaline Wastewaters

Membrane distillation (MD) utilizing low-grade thermal energy can be used to effectively desalinate hypersaline brines with a high freshwater recovery for water reuse. Membrane flux and durability are the two main indices used to evaluate MD membrane performance. In the past decade, electrospun nanofibrous distillation membranes (EFDMs) with a low mass transfer resistance have garnered increasing attention in MD research, owing to their high porosity and interconnected-pore structure. However, on the one hand, the pores of EFDMs compared to those of phase-inversion membranes are easily deformed and impacted by water flow, reducing membrane flux; on the other hand, the general hydrophobic interface is susceptible to being wetted, fouled and scaled during the desalination/concentration process, resulting in MD failure. This review will present a comprehensive discussion of the recent progress in electrospun nanofibers for the MD of hypersaline wastewaters with a focus on designing specially wettable membrane interfaces and welding-pore structured membranes to enhance MD distillation efficiency and durability simultaneously. Besides, the challenges and perspectives of MD in treating hypersaline wastewaters are also provided as a guide for future research on sustainable and clean freshwater recovery.