Graphene oxide quantum dots incorporated nanocomposite membranes with high water flux for pervaporative dehydration

Graphene oxide quantum dots (GOQDs), which inherit the monolayer of sp2 carbon atoms structure and hydrophilic groups as graphene oxide (GO) sheets, but with a quantum lateral size less than 100 nm, may hold great promise in membrane preparation. In this study, a novel nanocomposite membrane by mixing GOQDs with sodium alginate (SA) matrix was prepared for ethanol dehydration. GOQDs with an average lateral dimension around 3.9 nm provided additional shorter and less tortuous transport pathways for water molecules to penetrate the membrane compared to microsized GO sheets. Benefiting from the nanosize and high hydrophilicity of GOQDs, the nanocomposite membrane exhibited favorable ethanol dehydration performance with a total permeation flux of 2432 ± 58 g m−2 h−1, which was 60% higher than that of pristine alginate membrane, and a separation factor of 1152 ± 48. Incorporating GOQDs into the membranes can be an effective approach to improving the water permeation for water-permselective pervaporation membranes.