Uptake of CrO42- Ions by Fe-Treated Tri-Calcium Phosphate

Abstract

CrO4 2- ion adsorption on Fe-treated tri-calcium phos- phate was studied by batch experiments as a function of contact time, initial concentration of metal ion and temperature. Adsorption results showed that at pH 5.5 and 1.0x10 -4 M chromium concentra- tion the adsorption capacity of Fe-treated tri-calcium phosphate for CrO4 2- ions was 7.10 × 10 -3 mmol/g. Chromium adsorption data on Fe-treated tri-calcium phosphate at various initial concentration fitted the Freundlich isotherm. By temperature studies the thermodynamic parameters DH 0 , DG 0 and DS 0 were estimated and the obtained results showed that the adsorption reaction was endothermic and spontane-