Eco-Friendly and Efficient Extraction of AU from Waste Mobile Phones Using a Sodium Persulfate-Potassium Iodide System

Gold is one of the most fascinating resources in the wasted mobile phones (WMPs). In this study, a novel process for recovering Au from WMPs by Na2S2O8-KI leaching process combined with H2O2-H2SO4 pretreatment was developed. The mechanism of gold leaching in the Na2S2O8-KI system was studied. The acid pretreatment, effects of 4 factors on the gold extraction rate were explored. The results showed that acid pretreatment effectively improved the effect of gold leaching by removing most of Fe and Cu. And residual Fe and Cu could effectively activate persulfate and promote gold leaching in the Na2S2O8-KI system. The experimental conditions of the leaching step were also optimized: 0.02 mol L-1 Na2S2O8, 0.15 mol L-1 KI, 40℃, a solid-liquid ratio of 1: 20 (g/mL), and a stirring speed of 200 rpm. Under the optimal leaching parameters, the efficiency of gold leaching from WMPs attained 96% after 120 min. Due to the non-toxic and stable properties of Na2S2O8, the Na2S2O8-KI leaching process is more sustainable than conventional processes (iodine leaching, cyanide leaching)