(195c) Freestanding Ultrathin Graphene-Based Membranes for Water Purification

Graphene-based membranes, consisting of two-dimensional (2D) graphene oxide (GO) or reduced graphene oxide (rGO) nanosheets, have recently attracted increasing attention in separation of liquid mixtures. The nanochannels of these membranes, formed between 2D GO or rGO nanosheets, allow gases and ions with smaller sizes than those of the channels to permeate, while blocking all other larger species. However, hydration of GO in aqueous solution enlarges the channels, making it more challenging to be used in various exciting applications, such as desalination, energy production and hydrofracking water treatment. Although the hydration effect can be inhibited by reduction, a substantial loss in membrane permeability inevitably occurs. In this research, we aim to develop a next generation of high-flux and energy-efficient membranes based on graphene materials, and at the same time maintain their superior selectivity for precise ionic and molecular sieving in aqueous solution. Preliminary work has demonstrated the fabrication of freestanding ultrathin rGO membranes which are more selective and permeable than the state-of-the-art membranes in forward osmosis process. Future work will include further enhancement of the performance of graphene-based membranes in terms of permeability and selectivity, exploration of the uses of graphene-based membranes in other water treatment processes and understanding the mechanisms of mass transport in graphene-based membranes.