Forward osmosis membranes for high-efficiency desalination with Nano-MoS2 composite substrates

Abstract

Attractive membranes are critical for improving efficiencies of forward osmosis (FO) desalination process. In this study, a novel FO-PES-MoS2 thin film composite (TFC) membrane was assembled using the phase transfer method through merging MoS2 nanosheets into substrate casting solution. A sequence of characterization techniques was applied to test microstructures and physicochemical properties of the membranes and modification mechanisms based on MoS2 concentrations. Desalination efficiencies of the fabricated membranes were assessed by three NaCl draw solutions. Compared to the blank membrane, the MoS2-contained membranes had a thinner active layer, more upright and open pore structure, higher porosity, and lower surface roughness. 1wt% MoS2 content was the optimal modification condition, and water flux increased by 35.01% under this condition. Simultaneously, reverse salt flux of the FO-PES-1-MoS2 membrane declined by 29.15% under 1M NaCl draw solution, indicating increased salt ion rejection performance of the modified membranes. Moreover, Js/Jv ratio indicated that MoS2 nanosheets helped stabilize the desalination performance of the membranes. This study demonstrated that the novel FO-PES-MoS2 TFC membranes possessed improved performances and showed promising properties for saline water desalination.