Nanomaterials have been extensively used in polymer nanocomposite membranes due to the inclusion of unique features that enhance water and wastewater treatment performance. Compared to the pristine membranes, the incorporation of nanomodifiers not only improves membrane performance (water permeability, salt rejection, contaminant removal, selectivity), but also the intrinsic properties (hydrophilicity, porosity, antifouling properties, antimicrobial properties, mechanical, thermal, and chemical stability) of these membranes. This review focuses on applications of different types of nanomaterials: zero-dimensional (metal/metal oxide nanoparticles), one-dimensional (carbon nanotubes), two-dimensional (graphene and associated structures), and three-dimensional (zeolites and associated frameworks) nanomaterials combined with polymers towards novel polymeric nanocomposites for water and wastewater treatment applications. This review will show that combinations of nanomaterials and polymers impart enhanced features into the pristine membrane; however, the underlying issues associated with the modification processes and environmental impact of these membranes are less obvious. This review also highlights the utility of computational methods toward understanding the structural and functional properties of the membranes. Here, we highlight the fabrication methods, advantages, challenges, environmental impact, and future scope of these advanced polymeric nanocomposite membrane based systems for water and wastewater treatment applications.

We have developed a novel green synthetic method to covalently graft fluorographite (FGi) nanoplatelets, with quaternary ammonium polyelectrolyte chains under mild reaction conditions in water. Radical centers on the fluorographite layers react with the radical chain end on short strands of anion-exchange resins. While fluorographite is superhydrophobic, we show that the polymer radical chain end is necessary to initiate defluorination and delamination of the FGi in neutral pH water, without any pretreatment or caustic reagents. Scanning electron microscopy of thin films shows continuous and organized stacking of ellipsoidal nanoplatelets across large defect-free areas. We show that these new materials are highly effective at removing known and emerging contaminants to below environmentally relevant concentrations. Electron microscopy, vibrational spectroscopy, elemental analysis, and thermal analysis data are presented, and they are consistent with defluorination, partial exfoliation, and graphitization during the aqueous polymer grafting reaction. A radical-initiated mechanism is proposed that is consistent with the observed defluorination and oxidation of FGi nanoplatelets. The physicochemical properties, water flux, and morphology of these thin-film assemblies are described in detail. Thin membranes of polymerfunctionalized fluorographite removed 99% of perfluorooctanoic acid to below 100 parts per trillion while maintaining a very high water flux over 1100 L h(-1)m(-2) bar(-1). Percent removal of perfluorinated alkyl substances and heavy metal oxyanions versus polyelectrolyte-fimctionalized fluorographite membrane areal density is reported. The methodology presented in this study is a facile approach toward developing high-performance materials for sustainable and green applications.