Vapor‐Deposited Janus Membranes with Fouling Resistance for Desalination of Oil‐Contaminated Wastewater

Abstract Janus membranes with excellent fouling resistance and mass transport properties are highly desired to improve the performance and efficiency in the treatment of oil‐contaminated wastewater. The fabrication of Janus membranes requires control of both the membrane microstructure and the interfacial compatibility between distinct components. This work presents a vapor‐based strategy to incorporate Janus property into porous substrates without the wetting incompatibility in solution‐based Janus fabrications. The method allows for the retention of the membrane microstructure and the tuning of the modification depth for flux improvement. The integration of hydrophilic and omniphobic nanocoatings enables simultaneous resistance to emulsion wetting and oil fouling in the membrane distillation of oily wastewater. The Janus membrane demonstrates excellent desalination performance in treating oil‐contaminated wastewater, with >99.99% salt rejection at >230 g L −1 dissolved salt and stable permeate flux at oil content of 5 g L −1 .