Novel “loose” GO/MoS2 composites membranes with enhanced permeability for effective salts and dyes rejection at low pressure

Graphene oxide-based nanofiltration membrane, have attracted tremendous interest due to the highly permeability and excellent rejection behavior. Here we show that a novel low-pressure nanofiltration membranes (LPMs) comprising MoS2 nano-supporting spacer among the graphene oxide (GO) layers, which were fabricated by forward pressure-assisted assembly and heat-treatment. The resultant GO/MoS2 LPMs exhibited a pure water permeability about 10.2 ± 1.68 L/(m2·h·bar) at low pressure (2 bar), which was much higher ( about 13.6 times) than that of pristine GO membrane (~0.75 L/(m2 h bar)). Meanwhile, high rejection to different charged dyes ( ≥ 95%) and moderate rejection for salts (43.2%, 65.2%, 26.5% and 24.3% for NaCl, Na2SO4, MgCl2 and MgSO4, respectively) was remained. The satisfied filtration performance was attributed to the loose interlayer-structure of composite membrane and the cooperative effect of Gibbs-Donnan exclusion mechanism and steric hindrance. In addition, the GO/MoS2 LPMs presented satisfied stability and antifouling properties. Experimental results and molecular dynamics simulation results demonstrated that the increase of vertical distance between GO sheets by introducing the MoS2 nanoparticles could accelerate the water transport in the channels. This paper was not only provided a new design idea for adjusting the channel size of GO membrane, but also gave a promise of GO-based membrane for practical wastewater treatment and purification.