Desalination properties of a free-standing, partially oxidized few-layer graphene membrane

Abstract

Multi-stacked graphene oxide (GO) sheets containing intricate networks of microcapillary water channels are attractive as filtration membranes displaying both ultrahigh water permeation and ion exclusion properties. However, their practical utilization as desalination membranes is hampered by multiple issues, which include scalability, swelling of interlayer space, and mechanical instability under pressure-driven flux. To address these challenges, we have developed a process to laminate GO sheets with acryl binder to form large-area (>1 m2 in lab) free-standing membranes for high-performance desalination. The key to high-performance desalination lies in the control of interlayer spacing in the graphene sheets and the controlled oxidation of graphene. Our results show that the performance of partially oxidized few-layer graphene (POFG) is much better than heavily oxidized GO in forward osmosis (FO) due to its smaller interlayer distance and resistance to swelling. Our acryl-laminated, POFG membrane (79 L/m2/h water flux, 3.4 g/m2/h reverse salt flux) performs at least seven times (with respective to the water flux) and three times (with respective to the reverse salt flux) better than that of commercial cellulose triacetate (CTA) membrane (10 L/m2/h and 12 g/m2/h) in FO.