Graphene and Graphene-Based Composites: A Rising Star in Water Purification - A Comprehensive Overview

Graphene is an interesting two-dimensional carbon sheet possessing single-layered atom thickness that confers unique physical and chemical properties. The pristine graphene sheets have some limited applications in water purification, but the modification of graphene into the graphene composite by the incorporation of some functional groups or nanoparticles on the surface extensively increases its environmental applications. Recently, graphene nanocomposites have found to show very promising applications in all types of water purification. The present review highlights the recent developments in the applications of graphene and graphene-based composites as adsorbent, catalyst, photocatalyst, electrocatalyst, photo-electrocatalyst, and disinfection and desalination agent in comprehensive water purification systems. We primarily focus on the environmental engineering applications of graphene nanocomposites as sorbent materials for the elimination of toxic inorganic (cationic and anionic), organic, and mixed/multiple pollutants, and as catalysts for the degradation of toxic organic contaminants using catalytic oxidation, photocatalytic oxidation, electrocatalytic oxidation, and photoelectrocatalytic oxidation. We have also discussed the use and feasibility of graphene nanocomposites in water disinfection and desalination. Finally, the future challenges and perspectives are discussed.