Iron-doped hydroxyapatite for the simultaneous remediation of lead-, cadmium- and arsenic-co-contaminated soil

• Published in: Environmental pollution (1987) Vol. 312; p. 119953
• Main Authors: Yang, Zhihui, Gong, Hangyuan, He, Fangshu, Repo, Eveliina, Yang, Weichun, Liao, Qi, Zhao, Feiping
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.11.2022
• Subjects: Hydroxyapatite; Iron; Lead-cadmium-arsenic co-contaminated soil; Solidification/stabilization; Lead-cadmium-arsenic co-contaminated soil; Hydroxyapatite; Iron; Solidification/stabilization
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/j.envpol.2022.119953

Since lead, cadmium and arsenic have completely opposite chemical behaviors, it is very difficult to stabilize all these three heavy metals simultaneously. Herein, a novel iron-doped hydroxyapatite composite (Fe-HAP) was developed via an ultrasonic-assisted microwave hydrothermal method for the simultaneous remediation of lead-, cadmium-, and arsenic-co-contaminated soil in Hunan Province, South China. Using DTPA/sodium bicarbonate extractant to extract bioavailable Pb, Cd and As in soil after Fe-HAP remediation for 60 days, the immobilization efficiencies were 79.77%, 51.3% and 37.5% for Pb, Cd and As, respectively. The soil extractable and exchangeable fractions of Pb, Cd and As decreased significantly. In batch experiments, the adsorption kinetics of Pb, Cd and As on Fe-HAP were well described by pseudo-second-order models, indicating that the adsorption is controlled by chemisorption. In the Langmuir adsorption isotherm, the maximum adsorption capacities of Cd2+ and As(V) were 476.2 mg g−1 and 195.69 mg g−1, respectively, while Pb2+ fit the Freundlich model better. The XRD, SEM and XPS analyses indicated that Fe-HAP formed stable minerals of Pb5(PO4)3OH, Cd3(PO4)2·4H2O, Cd(OH)2 and Fe3(AsO4)2·6H2O with Pb, Cd and As. Overall, its facile and efficient immobilization performance indicate that Fe-HAP has potential for practical applications in integrative remediation of Pb-, Cd-, and As- co-contaminated soil. [Display omitted] •Fe-HAP was prepared by an ultrasonic-assisted microwave hydrothermal method.•The doping of Fe greatly enhanced the immobilization of Pb, Cd and As in soil.•Fe-HAP formed Pb5(PO4)3OH, Cd3(PO4)2·4H2O, and Fe3(AsO4)2·6H2O with Pb, Cd and As.•Simultaneous immobilization of Pb, Cd, and As in co-contaminated soils.