Aliquat-336 impregnated chitosan microspheres for Au(I) extraction from thiosulfate solution: Preparation, adsorption mechanism, and application

Abstract

In this paper, Ionic liquid Aliquat-336 impregnated chitosan microspheres (CMA) was synthesized and applied for Au(I) recovery from thiosulfate solution, which possessed adjustable particle size, good hardness and good selectivity adsorption capacity. The synthesis parameters (Aliquat-336 dosage and size) of CMA were explored. And the effects of initial solution pH, initial gold concentration, thiosulfate concentration and temperature on the gold(I) adsorption performance by CMA were was investigated systematically. The results showed CMA performed well over a wide pH range, and maximum gold adsorption capacity of 20.3 mg/g. Additionally, the gold adsorption behavior on CMA was similar to pseudo-first-order kinetics and the Langmuir model. SEM-EDS, FT-IR and XPS analyses confirmed that the mechanism of [Au(S2O3)2]3- adsorb on the CMA may be anion exchange. Notably, CMA exhibited an excellent selectivity for Au(I) in a Cu-ethylenediamine (en)-S2O32- solution. Loaded gold on CMA was easily eluted using a sodium sulfite solution, achieving a gold recovery of 62.2 %, even after four adsorption–desorption cycles. Finally, in the actual gold ore leachate adsorption and slurry adsorption method, the adsorption of gold and copper by CMA is approximately 98 % and 7 %, respectively. This study makes significant progress towards gold selective recovery in thiosulfate system, which is useful for the gold thiosulfate hydrometallurgy field.