Effect of Temperature on Interfacial Adsorption of Cr(VI) on Wollastonite

An extensive study on the effect of temperature on interfacial adsorption of Cr(VI) on wollastonite has been carried out. Adsorption on the wollastonite surface increased from 69.5 to 91.7% by increasing the temperature from 30 to 50 degrees C under optimum conditions. Kinetic modeling of the process of adsorption of Cr(VI) was done and various parameters were determined. The process follows a first-order kinetic equation and the rate of uptake was found to be 2.40x10(-2) min(-1) at 30 degrees C, 2.5 pH, 0.5x10(-4) M Cr(VI) concentration, and 0.01 M NaClO(4) ionic strength. Kinetic and equilibrium modeling of the process of adsorption was undertaken and the equilibrium parameters were determined. The process of adsorption follows pore diffusion and the value of the rate constant of pore diffusion was found to be 5.00x10(-3) mg g(-1) min(-1/2) at 30 degrees C and optimum conditions. The values of the coefficient of mass transfer, beta(L), were determined at different temperatures. Thermodynamic studies of the removal process were performed. The study suggests that the process is a typical example of endothermic adsorption. Copyright 2001 Academic Press.