Enhancing the property of composite pervaporation desalination membrane by fabricating a less resistance substrate with porous but skinless surface structure

The fabrication methods for high performance pervaporation (PV) desalination membranes were complicated and difficult to be scaled-up. To address this issue, we developed a composite membrane using a porous polysulfone (PSF) membrane that was prepared by a conventional non-solvent induced phase inversion (NIPS) technology. The key was to design the PSF structure with a skinless, macro-void free and bi-continuous cross-sectional morphology for achieving an ultra-low transport resistance. This was done by incorporating non-solvent additives of polyvinylpyrrolidone (PVP) and propionic acid (PA) into the PSF polymer dope and regulating the temperature of the water coagulant. As a result, the PSF based PV composite membrane exhibited a high-water flux of 124.8 ± 3.2 kg/(m2·h) and a salt rejection of 99.9% when separating a 3.5 wt% NaCl solution at 70 °C. Moreover, a water flux of 71.3 ± 1.8 kg/(m2·h) was achieved for treating a high concentrated NaCl solution of 20 wt%. To our best knowledge, these PV membrane desalination performances overshadowed all reported PV composite membranes using substrates fabricated by the NIPs method. Most importantly, the easy-to-scale-up membrane fabrication method, as well as the excellent PV desalination performance, indicated a great potential for industrial applications. Schematic diagrams of the water transfer processes across the high performance composite PV membrane. [Display omitted] •Optimization the polysulfone (PSF) substrate to obtain a macro-void free, inter-connected pores, and skinless structure by changing the casting solution composition and the temperature of coagulation bath.•Evaluation the composite membranes pervaporation (PV) performance and the substrate structure effect on the gas transport resistance.•The resistance to swelling polyvinyl alcohol (PVA) layer delamination and the long-term operational stabilities of the composite membrane.•Effects of temperature and salt concentration on the composite membranes desalination properties.•The high-water flux PV composite membrane, with a easy-to scale-up porous substrate, demonstrated a great potential for its composite PV membrane commercialization.