Recovery and reduction of Au(III) from mixed metal solution by thiourea-resorcinol-formaldehyde microspheres

To develop a novel adsorbent that can efficiently and rapidly recover gold from the leaching solution of electronic appliances, thiourea-resorcinol-formaldehyde resin microspheres (TRF) were prepared by a one-pot solvothermal method. Fourier transform infrared (FT-IR), thermogravimetric (TGA), X-ray diffraction (XRD), Transmission Electron Microscope (TEM), X-ray photoelectron spectroscopy (XPS), scanning electron micrograph and energy dispersive X-ray spectroscopy (SEM and SEM-EDS) were used to analyze the morphology and physical properties of TRF microspheres. The first time, TRF was successfully used to capture gold ions. The results showed that it had very high absorption capacity (1432 mg·g^-1), good selectivity (Au(III) ≫ Fe³⁺ > Ni²⁺ > Co²⁺ ≈ Cu²⁺ > Al³⁺ > Na⁺ ≈ K⁺) and excellent reuse performance for gold ions. Based on the study of adsorption isotherms and kinetics, Au(III) adsorption on TRF is mainly chemisorption and the adsorption sites are uniform. In acidic systems, Au(III) was reduced by TRF and deposited on TRF as elemental gold. This work provides the possibility to further develop the application of sulfur- and nitrogen-containing polymer materials in gold recovery from mixed metal solution.