Adsorption of Cr(VI) using Fe-crosslinked chitosan complex (Ch-Fe).

In the present investigation, Fe-chitosan crosslinked is used as adsorbent for the removal of chromium from aqueous solutions. The influence of pH, temperature and other ions was evaluated. pH 2.0 was found to be the optimum pH for adsorption of Cr(VI) onto Ch-Fe. Coordination of unsaturated sites for the iron(III) complex of polymer were considered to be the adsorption sites for Cr(VI) species, the predominant species being HCrO(4)(-). The Langmuir and Langmuir-Freundlich adsorption isotherm models were applied to describe the isotherm parameter for Cr(VI) adsorption. The results indicate that the Langmuir-Freundlich adsorption model and maximum adsorption capacity was calculated as 295 mg/g at 25 degrees C, with pH 4.7. Cr(VI) uptake on the adsorbent decreased from 295 mg/g at 25 degrees C to 209 mg/g at 65 degrees C. Rate constants as a function of temperature were evaluated with the help of a proposed second order kinetic model. The other coexisting ions, nitrate, chlorides and sulphate influenced Cr(VI) adsorption. 2010 Elsevier B.V. All rights reserved.