Graphene oxide and reduced graphene oxide coated cotton fabrics with opposite wettability for continuous oil/water separation

Fabrication of filtration membranes with opposite wettability for the separation of immiscible oil/water mixture has aroused extensive attention owing to the avoidance of oil/water density relationship limitation. Herein, we demonstrate a low-cost, mild and environment-friendly method to prepare underwater superoleophobic graphene oxide (GO) coated fabric through dip-coating of GO nanosheets onto cotton fabric, and the superhydrophilic GO coated fabric can be converted to superhydrophobic reduced graphene oxide (rGO) coated fabric after chemical reduction of the coated GO. The GO and rGO coated fabrics show excellent efficiencies for unidirectional separation of various light oils and heavy oils from water, respectively. Both types of fabrics could maintain their original wettability in harsh environments, and demonstrate high efficiency and recyclability for the separation of oil/water mixtures containing hot water, acid and salt. Furthermore, a T-shaped bidirectional separation device was devised by integrating the two fabrics with opposite wettability, which can realize high-efficient continuous separation of various oil/water mixtures regardless of the oil density.