Document Type : Original Research Paper
Authors
School of Mining Engineering, College of Engineering, University of Tehran, Tehran, Iran
Abstract
Deep eutectic solvents (DESs) have emerged as promising green alternatives for metal dissolution and recovery due to their low toxicity, ease of preparation, and tunable physicochemical properties. This study systematically investigated gold dissolution in three choline chloride-based DESs—ChCl:PTSA (1:2), ChCl:Oxalic acid (1:2), and ChCl:Lactic acid (1:2)—using H₂O₂ as an oxidizing agent. Gold leaching was conducted at 55, 60, 65, and 70 °C for 32 h, with dissolved gold monitored over time. At 70 °C, gold concentration in ChCl:PTSA (1:2) increased from 0.40 g L⁻¹ at 2 h to 1.20, 1.32, 1.61, and 2.00 g L⁻¹ at 4, 8, 16, and 32 h, respectively. For ChCl:Oxalic acid (1:2), dissolution reached 0.80, 1.30, and 2.13 g L⁻¹ at 8, 16, and 32 h, individually, while ChCl:Lactic acid (1:2) reached 0.70, 1.05, and 2.24 g L⁻¹ at the same times. At 70 °C and 32 h, final gold concentrations were 2.00, 2.13, and 2.24 g L⁻¹ for PTSA-, Oxalic acid- and Lactic acid-based DESs, for each system. Temperature primarily enhanced the dissolution rate during early leaching, while its effect on final dissolution was limited. Gold oxidation was attributed to reactive oxygen species generated from H₂O₂, with DES functional groups stabilizing dissolved gold through complexation. Overall, the results provide quantitative insights into temperature, leaching time, and HBD chemistry effects on gold dissolution.
Keywords
Main Subjects
)