Preparation of freestanding graphene-based laminar membrane for clean-water intake via forward osmosis process

Abstract

Here, a facile strategy is reported to prepare thin freestanding graphene oxide (GO) laminar membranes through thermally-induced chemical cross-linking process. The resultant freestanding cross-linked GO (F-CGO) membranes show controllable inter-laminar distance and hydraulic stability in aqueous media. Semi-permeability tests through a forward osmosis (FO) system show that the water permeation rate of the F-CGO membranes is up to 35.5 L m⁻² h⁻¹ when the draw solution is 2.0 mol L⁻¹ NaCl solution. This value is much higher than that of standing cross-linked GO (S-CGO) membranes, which indicates that the internal concentration polarization (ICP) effect has been alleviated by the F-CGO membrane. Furthermore, clean-water was taken in from various wastewaters, but without any detectable residual pollutants by using the F-CGO membrane as a separator. This work demonstrates that the F-CGO membrane is promising for water purification applications through the FO process, especially for portable water purification systems utilized during emergency situations.