Removal of Pb2+ from aqueous solutions by rock phosphate (low-grade)

In this study, removal of Pb2+ from aqueous solution by adsorption on rock phosphate (low-grade) has been investigated in batch experiments.1 The Pb2+ adsorption capability of the rock phosphate was evaluated as a function of pH, adsorbent dosage, contact time, initial Pb2+ concentration and temperature. Adsorption capacity of rock phosphate was found to be 200 mg Pb2+/g of adsorbent for initial Pb2+ concentration of 50 mg/L at 25 °C, while the adsorbent dosage was maintained at 0.25 g/L in pH 5 and contact time 120 min. Adsorption data obtained at 25, 35, 45 and 55 °C showed that the adsorption process was well-fitted with the pseudo-first-order adsorption rate expression and Langmuir adsorption isotherm. Activation energy obtained from kinetic data was found to be 33.6 kJ mol− 1.