Opportunities of Nanomaterials in Water Treatment Using Polymeric Membranes with Molecular Separation Ability

Liquid-phase membrane technology for reverse osmosis (RO), nanofiltration (NF), and pervaporation (PV) relies on membranes whose structure and compositionboth the polymeric matrix and the eventually incorporated fillerallow molecules to be discriminated by differences in size (related to diffusivity) and affinity (solubility). Since these technologies have reached commercial maturity, in recent years, further gains in membrane selective diffusivity and solubility have been sought from the use of nanomaterial additives, including porous oxides, zeolites, graphite-based derivatives, and metal−organic frameworks. This review examines, across RO, NF, and PV, which are the key nanomaterials offering the greatest improvements in molecular membrane separation performance for water treatment and discusses the mechanism by which they enhance the separation.