Selective hydrometallurgical recovery of gold by using low-cost biomass waste: Kiwi peel

Utilization of kiwi peel (KP) is proposed for gold recovery from electronic wastes (e-wastes). KP was simply modified by dehydration pretreatment with concentrated sulfuric acid. Among of the e-wastes metals, modified KP exhibited high selectivity on Au(III) adsorption. Ions dependencies on adsorption revealed that the increased chloride ion concentration has inhibition to Au(III) adsorption. After Au(III) adsorption, microscope images found gold particles on the adsorbents surface. X-ray diffraction analyses suggested that Au(III) reduction occurred along with the adsorption process, till the adsorption reached the equilibrium. Modified KP exhibited higher adsorption capacity (5.71 mmol g –1 ) than original KP (lower than 0.5 mmol g –1 ) or other natural adsorbents. Modification improved the adsorption capacity of KP. Gold was successfully recovered from the mixed precious metals through the adsorption and elution. KP waste is an applicable adsorbent with rich resource and high adsorption capacity.