Rapid and efficient recovery of Au(I) from cyanide gold leachate via quaternary ammonium-functionalized chitosan fibers: Insights into synthesis mechanism and adsorption behavior

For recovering gold from gold cyanide (Au(I)) leachate, quaternary ammonium (R₄N⁺) functionalized chitosan fibers (QECFs) were developed. The synthesis process was finely tuned via the Box–Behnken design to maximize Au(I) adsorption efficacy. Additionally, the environmental impacts and estimated manufacturing costs of preparing QECFs were assessed through life cycle assessment and economic analysis. The QECFs demonstrated exceptional maximum adsorption capacities of 669.75 ± 47.20 mg/g at pH = 9.5 within 15 min, surpassing reported adsorbents in both capacity and rate. Comprehensive characterization of adsorbents and mechanisms was conducted using DFT conclusion, FE-SEM, FT-IR, and XPS. The findings elucidated those electrostatic interactions between the R₄N⁺ on QECFs and Au(I), along with anion exchange involving Cl⁻ and Au(I), are integral to the adsorption mechanism. Furthermore, the QECFs could be swiftly regenerated using NaCl solution. The practical application of QECFs yielded a remarkable recovery efficiency of 98.2 % for Au(I) from WPCBs leachates, underscoring their potential utility in the gold recovery.