Role of water in vapor permeation through graphene oxide membranes†

Abstract

Membranes with atomic-level pores or constrictions are valuable for separation processes. Among these, graphene oxide (GO) membranes represent an emerging new class of separation membranes with unique ballistic and selective water transport through their nanocapillaries owing to their excellent hydrophilicity. Herein, we investigated the separation of binary aqueous and alcoholic vapors with acetone (AC) through GO membranes and discussed the critical vapor-permeation mechanism. The AC permeation in water was faster than those in pure AC and in AC in alcohol. This indicates that two molecules affect the permeation of the partner molecules during binary vapor permeation. In particular, binary vapor mixtures were difficult to separate in water because water increases the permeation speed of partner molecules. Meanwhile, the interaction between alcohol and AC molecules poses difficulty in achieving high flux because it slows the permeation of the partner molecules. GO membranes effectively separated butanol from the quaternary vapor. This study described the mechanisms in the vapor permeation of binary or multicomponent systems through atomic-scale channels in GO membranes, demonstrating the feasibility of GO membranes for vapor permeation.