Selective Sorption of Gold Ions from Iron-Rich Solutions Using a Dual-Phase Interpolymer System
Abstract
This study investigates the selective sorption of gold(I) ions from binary gold-iron solutions using the interpolymer system Amberlite IR120:AV-17-8. The system leverages remote interactions between cationic and anionic resins to enhance gold selectivity. Amberlite IR120 (H⁺ form) and AV-17-8 (OH⁻ form) were evaluated at molar ratios of 6:0, 5:1, 4:2, 3:3, 2:4, 1:5, and 0:6. Sorption characteristics were analyzed using gravimetry, inductively coupled plasma optical emission spectroscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis and scanning electron microscopy. The optimized 4:2 ratio exhibited the highest gold selectivity, achieving 96.26% sorption after 48 hours, while iron sorption remained at 42.33%. In contrast, Amberlite IR120 (6:0) showed negligible sorption (~3%), whereas AV-17-8 (0:6) reached 91.9% for gold and 92.33% for iron. Desorption with 9% thiourea and 2% sulfuric acid yielded 92.28% gold recovery and 46.44% iron recovery at the 4:2 ratio, which correlates with the high sorption efficiency. Based on calculations per mole of anion exchanger, the highest gold sorption was 18.45 mg/L at a 5:1 ratio, 301% higher than the 4.60 mg/L at a 0:6 ratio and gold desorption peaked at 15.4 mg/L at a 5:1 ratio, 266.67% higher than the 4.20 mg/L at a 0:6. These findings demonstrate that optimizing cation-anion ratios significantly enhances gold recovery. The system's efficiency is attributed to remote interactions and enhanced ion exchange, as analyzed using Pearson’s Hard and Soft Acids and Bases theory.