Hexavalent Chromium Adsorption on Magnetic Nanoparticles Synthesized from Tay Nguyen Red Mud from Vietnam

Abstract

Tay Nguyen red mud abundantly found in Vietnam, is a waste product of alumina production formed during processing of bauxite. It is rich in aluminate, residual alkaline, and oxides, such as silicon, iron, and titanium oxides. Iron oxide, which constitutes 45-55 % of Tay Nguyen, is useful for Fe3O4 nanoparticles synthesis. In this study, a Fe3O4 nanoparticles were synthesized using Tay Nguyen by the chemical co-precipitation method, which required a non-oxidizing oxygen-free environment. Fe3O4 nanoparticles were characterized using X-ray diffraction, field emission scanning electron microscopy, Brunauer-Emmett-Teller analysis, and vibrating-sample magnetometry. Adsorption of hexavalent chromium by the nanocomposite was conducted under batch conditions. Pseudo-second-order equations were used to describe kinetic data of adsorption reactions; the equations were fitted to kinetic data as shown by the results. The isotherms of adsorption were also studied using the linear forms of the Langmuir and Freundlich equations. The Langmuir equation exhibited higher linear correlation with the experimental data than the Freundlich equation did. The maximum monolayer coverage, qmax at 297 K was 31.44 mg/g.