Fabrication of in situ magnetic activated carbon by co-pyrolysis of sucrose with waste red mud for removal of Cr(VI) from waters

Abstract

Herein, a novel in situ magnetic activated carbon was prepared by co-pyrolysis treatment of sucrose, a renewable and rich carbon-based material, with waste red mud which industrial waste emerged as a result of aluminum oxide production from bauxite. Characterization studies were carried out by TGA, XRD, FT-IR, XPS, FE-SEM, VSM techniques, and N2 adsorption–desorption measurements and pHpzc. During the co-pyrolysis, while the metal oxides in the red mud show catalytic effect, the CO released from sucrose turns Fe2O3 into magnetic Fe3O4, which was confirmed by characterization studies. Adsorption efficiency of inorganic model pollutant Cr(VI) in aqueous solution was evaluated for magnetic activated carbon material with the most suitable surface properties. Maximum removal of Cr(VI) favored at solution pH of 2.10 ± 0.05, adsorption equilibrium time was 120 min and Freundlich isotherm model better modeled the adsorption data than Langmuir isotherm model. The experiments on the real water sample fortified with Cr(VI) indicated that the magnetic activated carbon could be successfully used for real sample without matrix effects.