Kinetics Studies on Toxic Hexavalent Chromium Removal from Aqueous Solutions by Magnetic Nano-Magnetite

Abstract

In this study, the chemical co-precipitation method was used to prepare magnetic nano-Fe3O4. In order to investigate the adsorption capacity of magnetic nano-Fe3O4 for Cr(VI) in aqueous solution, three aspects of solution pH, magnetic nano-Fe3O4 dosage and initial solution concentration were studied. The experimental results showed that Cr(VI) adsorption capacity by magnetic nano-Fe3O4 decreased with increasing pH and increased with the increasing initial concentration of Cr(VI) ions and magnetic nano-Fe3O4 dosage. In addition, the experimental data were fitted to the adsorption kinetics and three adsorption isotherms. It could be seen that the adsorption process of Cr(VI) by magnetic nano-Fe3O4 accorded with pseudo-second-order kinetics, which demonstrated that the adsorption process was controlled by chemical adsorption. And it was also found to be well represented by the Freundlich isotherm model. The maximum capacity obtained from the Langmuir model was 34.0136 mg/g, indicating that magnetic nano-Fe3O4 is an efficient adsorbent.