Kinetic and mechanism studies of the adsorption of lead onto waste cow bone powder (WCBP) surfaces |
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Authors: | Jihoon?Cha Mingcan?Cui Min?Jang Sang-Hyun?Cho Deok?Hyun?Moon Email author" target="_blank">Jeehyeong?KhimEmail author |
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Institution: | 1.School of Civil Environmental and Architecture Engineering,Korea University,Seoul,Korea;2.Korea Mine Reclamation Corporation, Technology Research Center,Seoul,Republic of Korea;3.Department of Environmental Engineering,Chosun University,Gwangju,Republic of Korea |
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Abstract: | This study examines the adsorption isotherms, kinetics and mechanisms of Pb2+ sorption onto waste cow bone powder (WCBP) surfaces. The concentrations of Pb2+ in the study range from 10 to 90 mg/L. Although the sorption data follow the Langmuir and Freundlich isotherm, a detailed examination reveals that surface sorption or complexation and co-precipitation are the most important mechanisms, along with possibly ion exchange and solid diffusion also contributing to the overall sorption process. The co-precipitation of Pb2+ with the calcium hydroxyapatite (Ca-HAP) is implied by significant changes in Ca2+ and PO4 3? concentrations during the metal sorption processes. The Pb2+ sorption onto the WCBP surface by metal complexation with surface functional groups such as ≡ POH. The major metal surface species are likely to be ≡ POPb+. The sorption isotherm results indicated that Pb2+ sorption onto the Langmuir and Freundlich constant q max and K F is 9.52 and 8.18 mg g?1, respectively. Sorption kinetics results indicated that Pb2+ sorption onto WCBP was pseudo-second-order rate constants K 2 was 1.12 g mg?1 h?1. The main mechanism is adsorption or surface complexation (≡POPb+: 61.6%), co-precipitation or ion exchange Ca3.93 Pb1.07 (PO4)3 (OH): 21.4%] and other precipitation Pb 50 mg L?1 and natural pH: 17%). Sorption isotherms showed that WCBP has a much higher Pb2+ removal rate in an aqueous solution; the greater capability of WCBP to remove aqueous Pb2+ indicates its potential as another promising way to remediate Pb2+-contaminated media. |
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