Bio-waste assisted phase transformation of Fe3O4/carbon to nZVI/graphene composites and its application in reductive elimination of Cr(VI) removal from aquifer

Abstract

This paper reportsa facile approach for the synthesis of graphene stabilisedzero valent iron (nZVI) via carbothermal reduction method using bio-waste materials. X-ray photoelectron spectroscopy confirmed the formation of nZVI, which was further supported by magnetic susceptibility measurements. The process of Cr(VI) removal was revealed by analysing nZVI/graphene before and after the Cr(VI) adsorption process. nZVI/graphene reduces Cr(VI) to Cr(III), which was adsorbed on the graphene sheet, avoiding the passivation of nZVI. Graphene provides good electrical conductivity, skeletal support, and has long-term electron releasing characteristics, which can accelerate the reduction of Cr(VI) to Cr(III) and demonstrates a quick and high removal capacity of Cr(VI) from an aquifer. The influence of Cr(VI) initial concentration, adsorbent dosages, equilibrium studies, solution pH, kinetics, adsorption isotherms, and thermodynamic parameters was also investigated.Synopsis.The green synthesis of nZVI/graphene compositesfor Cr(VI) reduction has not been well investigation. This paper reports a facile eco-friendly synthesis of nZVI/graphene composites for the removal of heavy metal contaminants from aquifers.