Selective Gold Ion Sorption from Iron-Containing Solution Using an Interpolymer System of Industrial Ion Exchangers

The escalating demand for precious metals in high-tech industries and jewelry, combined with the depletion of their reserves, underscores the need for efficient methods of gold recovery from industrial effluents. An interpolymer system comprising industrial ion exchangers KU-2-8 (in H⁺ form) and AV-17-8 (in OH^- form) demonstrated strong selective sorption capacity for Au(I) ions from a simulated Au(I)/Fe(II) mixed solution. The optimal KU-2-8:AV-17-8 (3:3) system achieved a sorption efficiency of 97.0% for Au(I) ions after 48 h with a desorption efficiency of 98.0% using a thiourea/sulfuric acid solution. The distribution coefficient (K_d) for Au(I) ions reached a maximum of 3233.3 mL/g at the 3:3 ratio, with a separation coefficient (β) of 40.62, indicating exceptional selectivity over Fe(II) ions. Fourier-transform infrared (FTIR) spectroscopy revealed structural changes post-sorption, including shifts in absorption bands (e.g., from 1273.5 cm^-1 to 1292.9 cm^-1) and the appearance of new bands (e.g., at 3171.1 cm^-1), confirming stable ion interactions. Thermogravimetric analysis/differential scanning calorimetry (TGA/DSC) demonstrated enhanced thermal stability post-sorption, with reduced mass loss up to 100 °C. These findings highlight the KU-2-8:AV-17-8 (3:3) interpolymer system's high selectivity, robust sorption capacity, and efficient desorption, presenting a sustainable solution for gold recovery in hydrometallurgical applications.