Stable Graphene Membranes for Selective Ion Transport and Emerging Contaminants Removal in Water

Abstract

AbstractCarbon‐based materials, such as graphene oxide and reduced graphene oxide membranes have been recently used to fabricate ultrathin, high‐flux, and energy‐efficient membranes for ionic and molecular sieving in aqueous solution. However, these membranes appeared rather unstable during long‐term operation in water with a tendency to swell over time. Membranes produced from pristine, stable, layered graphene materials may overcome these limitations while providing high‐level performance. In this paper, an efficient and “green” strategy is proposed to fabricate µm‐thick, graphene‐based laminates by liquid phase exfoliation in Cyrene and vacuum filtration on a PVDF support. The membranes appear structurally robust and mechanically stable, even after 90 days of operation in water. In ion transport studies, the membranes show size selection (>3.3 Å) and anion‐selectivity via the positively charged nanochannels forming the graphene laminate. In antibiotic (tetracycline) diffusion studies under dynamic conditions, the membrane achieve rejection rates higher than 95%. Sizable antibacterial properties are demonstrated in contact method tests with Staphylococcus aureus and Escherichia coli bacteria. Overall, these “green” graphene‐based membranes represent a viable option for future water management applications.