Electrospun\nNanofibrous\nPolyphenylene Oxide Membranes for High-Salinity Water Desalination\nby Direct Contact Membrane Distillation

Abstract

Desalination by the membrane distillation (MD) process\nhas been\nproposed to significantly increase the water recovery ratio, especially\ntreating with highly saline waters, for example, seawater and shale\ngas wastewater. However, the state-of-the-art membranes experience\nsevere wetting phenomenon, which generally leads to a performance\ndecline, resulting in inferior quality of the produced clean water.\nHerein we report, for the first time, an nanofibrous thin film based\non nonfluorinated poly­(2,6-dimethyl-1,4-phenylene oxide) (PPO) prepared\nby an electrospinning method for MD application. The inherently low\nthermal conductivity of PPO could well preserve the driving force\nacross the membrane during operation, while the corresponding nanofibers\nwith a rather smooth surface can prevent the adhesion of inorganic\nsalts, resulting in much enhanced anti-scaling behavior. Briefly,\nthe PPO membrane could provide a high water recovery ratio of 80 and\n60% for seawater and shale gas wastewater desalination, respectively,\nwith only 12.5 and 33% decline in water flux, respectively, whereas\n20.8 and 88.8% decline in water flux, respectively, was observed for\na commercial polyvinylidene difluoride membrane. Overall, we developed\na promising polymer candidate for fabricating novel membrane materials\nfor MD application and highlight its great potential for treating\nhighly salty water samples.