Reduced‐Graphene Oxide Nanofiltration Membranes Intercalated by Conjugated Polyaromatics: Towards High Monovalent Salt Rejections

Graphene oxide (GO) nanofiltration (NF) membranes have emerged as promising candidates for processing of aqueous streams, due to fast water transport characteristics and excellent chemical stability in harsh operating environments. Their practical applications under realistic high salt/solute concentration conditions are challenged by a lack of systematic approaches to control selectivity, as well as membrane swelling and mechanical stability. Here, we show that intercalation of rGO (reduced GO) membranes with polyaromatic conjugated molecules of different structural classes is an effective strategy to enhance and tune their performance. Specifically, these membranes allow entry into a "deep NF" regime with remarkably high inorganic monovalent salt rejections (NaCl, 75-85%) and near-total divalent salt rejections (Na₂SO₄, ∼98%) in a large concentration range (0.01-0.1 M) while maintaining high water permeability.