A novel UiO-66-NH2/graphene oxide composite thin membrane for retarding membrane wetting in membrane distillation

Abstract

Membrane distillation (MD) is considered an emerging desalination technology. However, the presence of surfactants allows liquid to penetrate the membrane, resulting in membrane wetting, which hinders the commercialization of MD. In this study, we use very few modified materials to prepare novel Janus thin membranes that immobilize modified materials (graphene oxide (GO) and UiO-66-NH₂) on polytetrafluoroethylene (PTFE) hydrophobic base membranes via crosslinkers. The composite thin membrane properties with eight different ratios and contents of GO and UiO-66-NH₂ were fabricated and tested by a feed solution of sodium chloride containing a high concentration of sodium dodecyl sulfate. An optimal ratio of Janus membrane with high flux without affecting the effluent water quality was obtained. The Janus membrane exhibited excellent anti-wetting properties compared to the original PTFE membrane. A desalination rate of up to 99.9% was still available even under 48 h of long-term operating conditions by maintaining a flux of approximately 21.2 L/(m²·h). The anti-wetting mechanism of this membrane was further confirmed by the modified XDLVO model. It suggested that the novel Janus membrane could be a highly promising substitute to the MD process for the resource-based treatment of surfactant-containing wastewater, which played an important role in promoting its application.