Uniform hydrophobic electrospun nanofibrous layer composed of polysulfone and sodium dodecyl sulfate for improved desalination performance

Abstract

Recently, water reclamation and water reuse have received considerable attention because of high water demand. Membrane processes constitute the most convenient technology for water treatment and desalination. In this study, a novel class of enhanced performance membranes consisting of a highly hydrophobic nanofibrous layer and hydrophilic cellulose filter paper (CFP) for membrane distillation (MD) was thoroughly examined. The nanofibrous layer was produced through electrospinning of polysulfone (PSF) doped with a sodium dodecyl sulfate (SDS) surfactant for uniformity and homogeneity in fiber diameter. The SDS surfactant was found to be the ideal additive for increasing the conductivity of the PSF polymeric solution, which helps in lowering the critical voltage required to initiate the electrospinning process, resulting in greater elongation of the nanofibers because of the increase in charge density. In the fabricated membranes, the PSF–SDS nanofibrous layer acts as a top active layer, whereas the CFP acts as the bottom supportive layer. Cellulose paper can absorb water molecules, which enhances vapor flux across the membrane in MD. The surface area, pore size distribution, fiber diameter, mechanical strength, water flux, and rejection percentage of the modified dual-layer PSF–SDS/CFP membranes were studied. The salt rejection of the PSF–SDS/CFP membrane was more than 99%, and a high permeate flux of approximately 9LMH was maintained for long-term operation of 16h.