Capture and Extraction of Gold from Aqueous Solution via the Iron Electrocoagulation Method

Abstract

Gold mining from gold sources, such as natural ores, electronics, and other industrial wastes, is not yet feasible in terms of environmental costs and production efficiency. The trace quantity of Au in the aqueous solution limits its effective capture and extraction through conventional methods. Here, we report a homogeneous, spontaneous, and selective Au-capture method via iron electrocoagulation. Exhibiting a strong electronegativity that distinguishes Au from other metals, water-dispersed Au ions are readily adsorbed by in situ crystallized positively charged ferrous colloidal nuclei. This process involves no chemicals, but it can be performed using an insignificant cell voltage, 0.2 V, with an extraction efficiency of ∼100%. Interestingly, Au0 sponge flocs are obtained in the precipitate, indicating a synchronous reduction reaction. By demonstrating the success of electronic waste and gold-ore pilot tests, we suggest that this approach might be feasible for industrial use. This research opens a new path in the development of sustainable technologies for gold extraction, thereby contributing to a scalable circular economy.

Dual-Crosslinking Polydopamine/Poly(imide dioxime) Porous Network Membrane Enables Efficient and Selective Gold Recovery from e-Waste

“…From the survey spectrum in Figure a, as compared to the pristine PDA/PIDO, two new peaks can be observed in the postsorption membrane, corresponding to Au 4d and Au 4f peaks, respectively. The high-resolution spectrum of Au 4f at 84.0 and 87.6 eV peaks, assigned to the respective Au 4f 7/2 and Au 4f 5/2 , can be further deconvoluted into several characteristic bands associated with Au(0) 4f 5/2 (87.58 eV), Au(0) 4f 7/2 (83.88 eV), Au(I) 4f 5/2 (88.68 eV) and Au(I) 4f 7/2 (85.08 eV), Au(III) 4f 5/2 (90.18 eV), and Au(III) 4f 7/2 (86.38 eV) (Figure b) . The coexistence of Au(0), Au(I), and Au(III) confirms that the adsorbed Au(III) is first reduced to the intermediate Au(I) and then into Au(0) during the process of gold recovery by the PDA/PIDO membrane, consistent with the former TEM and HRTEM results.…”