Graphene coated iron oxide (GCIO) nanoparticles as efficient adsorbent for removal of chromium ions: Preparation, characterization and batch adsorption studies

Abstract

Graphene coated iron oxide nanoparticles were prepared using microemulsion method for removal of Cr(VI) ions from aqueous solutions. Plausible interactions between the material and Cr(VI) ions were explored after adsorption and explained by characterizing through various analytical techniques such as Raman spectroscopy, LIBS, FTIR, TEM, EDX, SEM, particle size and zeta-potential measurements which confirmed 20% crystalline nature of GCIO, nanorange (50 nm) size of nanoparticles and great thermal stability. A simple, sensitive and highly selective direct spectrophotometric method was used for the determination of trace levels of Cr(VI) and various experimental parameters, such as the effect of time, pH, adsorbent dose, chromium concentration, temperature and composition of nanoparticles were studied on the adsorption of chromium. The equilibrium sorption data were fitted to various adsorption isotherm models and the as prepared GCIO adsorbent was found to follow the pseudo second order kinetics (R2 = 0.97) and Freundlich model isotherm (R2 = 0.97) with high adsorption capacity (352.1126 mg/g) for Cr(VI) adsorption. The nanoadsorbents were also found to be fairly reusable.