Methanol/dimethyl carbonate separation using graphene oxide membrane via cationic control of molecular transport channels

The separation of small molecular organic-organic mixtures by membranes show considerable potential in energy efficiency, while the performance of polymeric membranes is unattractive. Two-dimensional (2D) graphene oxide (GO) membranes having ultra-fast and selective molecular transport channels could be an ideal platform for separating the organic-organic mixtures, however, such potential is not fully explored. In this paper, towards pervaporation separation of methanol (MeOH)/dimethyl carbonate (DMC) solvents, GO membrane with tunable interlayer and stable structure was prepared by anchoring metal ions between GO sheets. The introduced cations formed cation-π interaction with the sp² region of GO, and electrostatic attraction with carboxyl, hydroxyl and epoxy groups on GO sheets. The molecular transport channels of GO membrane was optimized by optimizing the cation species (Na⁺, K⁺, Zn²⁺, Ca²⁺), cation content and GO flake sizes. The total flux of GO-Zn²⁺ membrane is 707.3 g/(m²·h) as well as separation factor is 61.9 for separation of 10 wt% MeOH/DMC mixtures by pervaporation at 50 °C. Meanwhile, the cationic control highly enhanced the stability of the GO membrane during continuous pervaporation process. This work reveals that GO membranes are the feasible for the application in pervaporation separation of organic-organic mixtures.