Fabrication of high-performance composite membranes based on hierarchically structured electrospun nanofiber substrates for pervaporation desalination

Abstract

Electrospun polyacrylonitrile (PAN) nanofiber membrane was fabricated. The surface of the PAN nanofiber membrane was spray-coated with a hydrophobic paint or knife-casted with an ultra-fine nanofiber cellulose (NC) layer. This was to mitigate the problem of infiltration of the coating solution into the pores of the virgin PAN nanofiber membrane when preparing composite membranes. As a result, defect-free and thin PVA layers were successfully deposited onto the hydrophobic PAN nanofiber or NC-PAN nanofiber substrates by a spray-coating method. The thin film composite (TFC) PVA/NC-PAN membrane exhibited extradentary pervaporation desalination properties. A water flux of 238.7 ± 4.1 kg/m2·h and a salt rejection above 99.8% were obtained using a 3.5 wt% NaCl solution as feed at 80 °C. This is the highest reported water flux of all the PV desalination membranes. Moreover, a high-water flux of 103.1 ± 5.8 kg/m2·h was observed using the composite membrane to desalinate a 20 wt% NaCl solution at 70 °C. The excellent desalination property of the PV composite membrane demonstrates a great potential for recycling brine solutions.