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

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. 1 wt% 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 1 M NaCl draw solution, indicating increased salt ion rejection performance of the modified membranes. Moreover, J_s/J_v 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.