Recovery of gold and iodine from the effluents of semiconductor industry using activated carbon

摘要

This research work focused on using activated carbon to recover gold (40.5 mg/L) and iodine (748 mg/L) from the effluents of semiconductor industry. The effects of various process parameters such as contact time, activated carbon dose etc. were investigated for recovery of gold and iodine. The loading capacity of activated carbon for adsorption of gold and iodine was found to be 33.5 mg gold/g carbon and 835 mg iodine/g carbon. Gold was found to exist on the surface of activated carbon in two forms: ionic gold and elemental gold. The elution of gold was carried out in aqua regia by converting all metallic gold to ionic form and removing small amount of ionic gold adsorbed on the activated carbon to solution. Gold was recovered from the eluted solution by the reduction process. Iodine was then recovered from the diluted aqua regia solution by adding sodium hyposulfite (Na2S2O4) to get precipitated iodine solid.