Interplay of adsorptive properties and dielectric reactivity of graphenes upon edge functionalization

Abstract

Graphenes have unique physicochemical properties that can be engineered for pollutant adsorption even under natural organic matter competition and their dielectric properties can facilitate subsequent microwave regeneration. Firstly, graphenes have the potential for high-level control of oxygen content at the edges of the material without compromising the conjugated electronic structure of the basal plane. Because the basal plane contains lightly functionalized sp2-hybridized carbon atoms while sp3-hybridized ones are on the periphery of the sheets. Edges of graphenes can be oxidized while the basal plane can still be electronically stable with conjugated π-electrons perpendicular to the graphene lattice. For this, graphenes can be oxidized to attain controlled dispersion in water without disrupting the conjugated electron network on the basal plane, which is critical for pollutant adsorption. Graphenes have sheet-like surfaces that form dynamic, porous aggregates in water and can facilitate synthetic organic compound adsorption by the complex interplay of ‘pore’ accessibility and favorable intermolecular interactions. Thus, studying the role of oxidation of graphenes can help unravel the interplay between inter-sheet distance and the adsorption of synthetic organic compounds under natural organic matter competition. Secondly, the sp2 hybridized basal plane of graphenes has mobile π-electrons that are expedient for rapid dielectric heating, which can be harvested for rapid and efficient microwave regeneration. Fundamental research on graphene chemistry can lead to a paradigm shift in the water treatment industry towards the safe and sustainable deployment of regenerable nano-scale adsorbents. This article presents a perspective on how to approach edge functionalization of graphene with an aspiration to advance their safe and sustainable use in water treatment.