Chitosan/graphene oxide mixed matrix membrane with enhanced water permeability for high-salinity water desalination by pervaporation

Abstract

Pervaporation is a promising technology for water desalination. In this work, graphene oxide (GO) was incorporated into chitosan (CS) to fabricate mixed matrix membranes (MMMs) to explore the enhancement of water permeability for high-salinity water desalination and to understand the transport mechanism in the MMMs. The effect of GO content on the morphology, wettability and desalination performance of the membranes as well as the thermodynamic and kinetic behavior of water and salt permeation in the membranes were investigated. The MMMs have rougher and more hydrophilic surface, dense structure and improved mechanical stability owing to the good chemical compatibility of GO with CS matrix. The apparent activation energy results indicate the advantage of the MMMs in desalinating high-salinity water. The enhanced permeate flux of 30.0 kg/m2·h was obtained in desalinating 5 wt% aqueous NaCl solution at 81 °C with 1 wt% GO content and 99.99% of salt rejection was achieved. The solubility and diffusivity of H2O and NaCl in the MMMs demonstrate a trade-off effect on the water permeability and water/salt selectivity with increasing of GO content. The NaCl diffusion coefficient in the membranes was lower than that of H2O by two orders of magnitude, contributing to the high selectivity of the membrane.