From Gold Mining Waste to Functional Sorbents: Structural and Compositional Insights into Copper Adsorption Efficiency
Kalymbet A. Kubekova S. Kapralova V. Lavrova S.
December 2025Engineered Science Publisher
ES Materials and Manufacturing
2025#30
This study explores the transformation of Akbakay gold ore waste into effective sorbents for heavy metal removal through phosphoric acid modification (20–35 wt.%) and thermal treatment at temperatures ranging from 400 to 800 °C. A range of characterization techniques—including XRD, EPMA, FTIR, SEM, BET surface area analysis, and zeta potential measurements— revealed notable structural changes. These included the formation of phosphate phases (such as lipscombite), increased porosity, surface fragmentation, and a more negative surface charge (up to −20.1 mV). Among the samples, the one treated at 600 °C with 20 wt.% acid (Sample 3) demonstrated outstanding Cu²⁺ removal efficiency (>97 %) across initial concentrations of 1–40 mg/L, achieving a maximum adsorption capacity of 1.33 mg/g. The adsorption behavior followed the Langmuir isotherm model, indicating monolayer adsorption on a uniform surface. Kinetic analysis showed rapid metal uptake, with over 99 % removal within 120 minutes, best described by a mixed-order model that reflects both physical and chemical adsorption mechanisms. Fixed-bed column experiments further confirmed the materials performance, achieving a dynamic capacity of 0.847 mg/g and over 83 % Cu²⁺ removal. Breakthrough occurred at approximately 25 mL, with no 95 % breakthrough observed even at 300 mL. Overall, this work highlights a promising approach for converting mining waste into efficient, low-cost sorbents, contributing to sustainable heavy metal remediation and waste valorization efforts.
Copper adsorption , Heavy metal removal , Mining waste valorization , Thermal modification , Waste-derived sorbents
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Department of Chemical Processes and Industrial Ecology, Mining and Metallurgical Institute named after O.A. Baikonurov, Satbayev University, 22 Satbaev street, Almaty, 050013, Kazakhstan
Department of Environmental Engineering, Faculty of Chemical and System Engineering, University of Chemical Technology and Metallurgy, 8 Kliment Ohridski blvd, Sofia, 1756, Bulgaria
Department of Chemical Processes and Industrial Ecology
Department of Environmental Engineering
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