In situ lead immobilization by apatite
Lead contamination is of environmental concern due to its effect on human health. The purpose of this study was to develop a technology to immobilize Pb in situ in contaminated soils and wastes using apatite. Hydroxyapatite [Ca 10 (PO 4 ) 6 (OH) 2 ] was reacted with aqueous Pb, resin-exchangeable Pb, and Pb-contaminated soil material. The effectiveness of natural apatite to attenuate Pb was also tested. Hydroxyapatite reduced initial Pb concentrations of 5-500 mg L -1 to 0.18-19.7 μg L -1 . Aqueous Pb in Pb-contaminated soil materials was reduced from 2273 to 36 μg L -1 after reaction with hydroxyapatite. We hypothesize that Pb was immobilized by dissolution of hydroxyapatite and precipitation of hydroxypyromorphite [Pb 10 (PO 4 ) 6 (OH) 2 ]