Investigation of Chromium Removal by Adsorption/Precipitation Techniques using Solid Waste Material

Abstract

Experimental investigation of trivalent chromium Cr(III) removal by using solid waste material (bypass cement kiln dust (BCKD)) were conducted by varying of various parameters such as contact time, initial chromium ion concentration, BCKD dose and initial pH. Investigations show that an optimum range of removal by adsorption is ranged (2-3) while increasing of pH up to range (6.5-8) that gave a best percentage of removal by precipitation process. Langmuir and Freundlich isotherm models were applied to the equilibrium data. Results shown that the percentage adsorption increased with decrease in pH and showed maximum removal of Cr(III) at initial pH value 2.5. Also thermodynamic parameters such as standard Gibbs energy ΔG^o, heat of adsorption ΔH^o and entropy ΔS^o were estimated. These thermodynamic parameters showed the process to be endothermic in nature. Desorption of Cr(III) from the spent BCKD has also been investigated. Desorption process suggest that the adsorption of Cr(III) ions on BCKD involves physisorption mechanism.