Synthesis of novel magnetic activated carbon for effective Cr(VI) removal via synergistic adsorption and chemical reduction
Zhenyu Wu, Hua Zhang, Enas Ali, Asfandyar Shahab, Haiyi Huang, Habib Ullah, Honghu Zeng
Abstract
The removal of a toxic contaminant like Cr(VI) from the water via green adsorbents like biochar and activated carbon is an eco-friendly technique. In this paper, using commercial activated carbon as a raw material, magnetic ferric oxide/activated carbon (Fe3O4@AC) was prepared by the chemical co-precipitation method, and Cr(VI) adsorption in water was applied. The synthesized materials were characterized by advanced characterization techniques including XRD, BET, FT-IR, and XPS. The effects of initial Cr(VI) concentration, temperature, and adsorption time on the adsorption effect of Cr(VI) were evaluated. Results illustrated that the maximum Cr(VI) adsorption achieved by Fe3O4@AC was 45.3 mg/g, with a removal rate of 88.8% at the optimum pH of 2.0 and an adsorption time of 12 h. Under these conditions, Cr(VI) adsorption by Fe3O4@AC fits the pseudo-second-order kinetic model (PSO) and Langmuir isotherm model and is a spontaneous, endothermic, and irreversible process. The results of BET, XRD, FT-IR, and XPS characterization analysis of Cr(VI) before and after adsorption suggested that the adsorption mechanism of Fe3O4@AC is mainly based on chemisorption, supplemented by physical adsorption, accompanied by electrostatic attraction and complexation.