Chromium(VI) removal from aqueous solution using a new synthesized adsorbent

In order to effectively utilize agricultural wastes, the feasibility of using a novel calcined composite of dolomite, montmorillonite, and corn stover for removing chromium(VI) from aqueous solutions was examined. Batch experiments were conducted to investigate the effect of composite dosage, solution pH, initial concentration of chromium(VI), and temperature during the removal process. Chromium(VI) removal efficiency increased with increase in amount of the composite but remained almost unchanged (84-86%) when the solution pH increased from 2.0 to 11.0. The increase in chromium(VI) removal efficiency with increase in temperature from 20 to 40 degrees C indicated that high temperature favored the removal process. This conclusion was also confirmed by adsorption energy evaluation where the reaction process was found to be endothermic and spontaneous. The removal process well fitted the pseudo-second-order kinetic model. Fitting of the experimental results with the intraparticle diffusion model revealed that the adsorption process was not controlled by the intraparticle diffusion. Isotherm studies demonstrated that the homogeneity of the composite surface and physical forces may more significantly affect the removal process.