Speciation of toxic metals in metal finishing filter cake by X-ray absorption spectroscopy.

Autor: Chen DT; Department of Civil, Environmental and Geomatic Engineering (CEGE), University College London (UCL), Chadwick Building, Gower Street, London, WC1E 6BT, UK., Roy A; Louisiana State University Center for Advanced Microstructures and Devices, Baton Rouge, LA, 70806, USA., Bogush A; Department of Civil, Environmental and Geomatic Engineering (CEGE), University College London (UCL), Chadwick Building, Gower Street, London, WC1E 6BT, UK., Stegemann JA; Department of Civil, Environmental and Geomatic Engineering (CEGE), University College London (UCL), Chadwick Building, Gower Street, London, WC1E 6BT, UK. Electronic address: j.stegemann@ucl.ac.uk.
Jazyk: angličtina
Zdroj: Journal of environmental management [J Environ Manage] 2024 Jun; Vol. 360, pp. 120994. Date of Electronic Publication: 2024 May 14.
DOI: 10.1016/j.jenvman.2024.120994
Abstrakt: The speciation of Cr, Zn, Cu and Pb in two metal finishing filter cakes (TX and ST) was investigated by X-ray absorption spectroscopy (XAS) complemented by X-ray fluorescence (XRF) and X-ray diffraction (XRD). XRF showed that concentrations of Cr, Zn, Cu and Pb were 1.4%, 0.19%, 0.20% and 0.01%, respectively, in TX, and 12.6%, 3.3%, 1.3% and 0.21% in ST. No crystalline phases were detected in TX by XRD whereas ST was dominated by calcite. Cr and Fe K edge XAS showed Cr to be trivalent and octahedrally coordinated, co-precipitated with Fe as Cr x Fe 1-x -(oxy)hydroxides in both filter cakes. Zn, P and Ca K edge XAS showed that 2ZnCO 3 ∙3Zn(OH) 2 and Zn 3 (PO 4 ) 2 were the dominant zinc-containing phases, with combined tetrahedral and octahedral coordination; Zn phases were slightly more crystalline in TX than ST. Pb L 3 edge X-ray absorption near edge spectroscopy (XANES) found that Pb was likely adsorbed on amorphous SiO 2 . Cu, Si and S K edge XAS showed that all Cu was divalent, and the dominant copper phases were found to be Cu 2 Cl(OH) 3 , Cu(OH) 2 and CuSO 4 ·5H 2 O for ST, whereas Cu appeared to adsorb to amorphous SiO 2 for TX, which contained much less Pb. Cr is thus immobilized in the filter cakes in a phase with low solubility at environmentally feasible pH values, whereas Zn, Cu and Pb could be released when the pH decreases below 8 or above 11. These findings are significant for the development of waste management regulations and/or metal recovery methods (e.g., hydro/pyrometallurgy).
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
(Copyright © 2024. Published by Elsevier Ltd.)
Databáze: MEDLINE
Externí odkaz: