Selective removal and simultaneous immobilization of Pb cations from solutions

Abstract

ABSTRACT The aim of this study was to develop a layered ammonium tin phosphate as a potential sorbent for removal of Pb2+ ions by exchange/sorption or other mechanism from contaminated solutions. A layered ammonium tin phosphate (NH4-SnP), δ-SnP – NH4 was synthesized using the hydrothermal process. XRD pattern of the NH4-SnP revealed that the final product obtained was δ-tin (IV) phosphate with the d(001)-spacing of about 14.8 Å containing ammonium ions and water molecules in the interlayers. In order to investigate the removal efficiency of Pb2+ cations by the NH4-SnP, batch-type of sorption experiments were carried out with 2 days of equilibration time at room temperature. Also, the kinetics of reaction was performed at room temperature to determine equilibrium time. The sorption isotherms for Pb2+ cations indicated that NH4-SnP showed high affinity for these ions with all the concentrations used. In addition, kinetic data showed preference for Pb2+ cations between NH4 + cation on the exchanger and Pb2+metal cation in solution. Based on these results, NH4-SnP can be proposed as an excellent sorbent for not only removal but also immobilization of Pb2+ ions from water and wastewater. Pb2+ ions were found to be immobilized as insoluble pyromorphite, Pb5(PO4)Cl after high uptakes.