Adsorption of phosphate from aqueous solutions using calcined waste eggshell

In this study, removal of phosphate from aqueous solutions was examined using calcined waste eggshell (CWE). The pore properties including the BET surface area, pore volume, pore size distributions were characterized. In the batch mode adsorption studies, the effects of calcinations temperature of eggshell, contact time, temperature, initial phosphate concentration of solution, adsorbent dosage, initial pH and other ions on the phosphate adsorption by the CWE have been studied. A comparison of kinetic models applied to the adsorption of phosphate onto CWE was evaluated for the pseudo-first order and pseudo-second order kinetic model. The experimental data fitted very well the pseudo-second order kinetic model. In the isotherm studies, the Langmuir, Freundlich and Dubinin-Radushkevich (DR) isotherm models were applied. The results indicate that Freundlich equation is well described with the phosphate adsorption. Desorption and recovery of phosphate studies were carried out. (C) 2011 Elsevier B.V. All rights reserved.