Equilibrium Sorption of Hexavalent Chromium from Aqueous Solution Using Iron(III)-Loaded Chitosan-Magnetite Nanocomposites As Novel Sorbent

Abstract

This work describes magnetic separation of hexavalent chromium by iron(III)-loaded chitosan-magnetite nanocomposites. The Cr(VI) uptake data, studied at 25°C and 45°C, was well fitted into the Freundlich isotherm. The values of constant K_F and 1/n were found to be 1.515, 1.266 and 1.006 (mg g⁻¹) (l mg⁻¹)^1/n and 0.76, 0.77, and 0.71, respectively. The Dubinin-Kaganer-Radushkevich isotherm was applied to determine mean sorption energy E. The value of E was found to be in the 8.977 to 9.90 kJ mol⁻¹ range, thus indicating the chemical nature of the sorption process. The kinetics of Cr(VI) uptake was best interpreted by the Power function model. The intraparticle diffusion of sorbate was confirmed by the Bangham equation, and various thermodynamic parameters were also evaluated. Finally, a plausible mechanism has been suggested to understand the sorption process. The intraparticle diffusion was found to occur and later on confirmed by the Bangham equation. Finally, a plausible mechanism has been suggested for the observed Cr(VI) uptake on this newly developed sorbent. The various thermodynamic parameters were also evaluated.

Keywords:

• Sorption
• chitosan
• magnetite
• Freundlich
• power law