One-step synthesis of Fe2O3 nano-rod modified reduced graphene oxide composites for effective Cr(vi) removal: removal capability and mechanism

Abstract

Reduced graphene oxide (rGO) supported Fe₂O₃ nanorod composites were prepared via a one-step hydrothermal method and further utilized for hexavalent chromium (Cr(VI)) removal from aqueous environments. The composite material exhibited an excellent removal efficiency for chromium (47.28 mg L⁻¹), which was attributed to the electrostatic attraction and chemical reduction of chromium by the material. The removal mechanism was studied by SEM, BET, XPS, and FTIR. The results demonstrated that rGO was successfully modified by Fe₂O₃ nanorods (approximately 50 nm wide). Compared with graphene oxide (GO), the compound was much more easily separated from the solution after completing the removal. Furthermore, XPS characterization showed that Cr(VI) could also be reduced to low-toxicity Cr(III) by hydroxyl groups. In the variables test, it was found that the removal process was pH-dependent. The results of the designed experiments for exploring the adsorption kinetics, isotherms and thermodynamics indicated that the removal process obeyed a pseudo-second-order kinetics model, Langmuir isotherm model and that it was a spontaneous exothermal process. This study provides the possibility of hydrothermal synthesis of Fe₂O₃/rGO for use as an excellent material to remove Cr(VI) from aqueous environments.