Selective recovery of Cu(II) from strongly acidic wastewater by zinc dimethyldithiocarbamate: Affecting factors, efficiency and mechanism

The selective recovery of copper from strongly acidic wastewater containing mixed metal ions remains a significant challenge. In this study, a novel reagent zinc dimethyldithiocarba-mate (Zn(DMDC)2) was developed for the selective removal of Cu(II). The removal efficiency of Cu(II) reached 99.6% after 120 min reaction at 30 degrees C when the mole ratio Zn(DMDC)2 /Cu(II) was 1:1. The mechanism investigation indicates that the Cu(DMDC)2 products formed as a result of the displacement of Zn(II) from the added Zn(DMDC)2 by Cu(II) in wastewater, due to the formation of stronger coordination bonds between Cu(II) and the dithiocarbamate groups of Zn(DMDC)2. Subsequently, we put forward an innovative process of resource recov-ery for strongly acidic wastewater. Firstly, the selective removal of Cu(II) from actual wastew-ater using Zn(DMDC)2, with a removal efficiency of 99.7%. Secondly, high-value CuO was re-covered by calcining the Cu(DMDC)2 at 800 degrees C, with a copper recovery efficiency of 98.3%. Moreover, the residual As(III) and Cd(II) were removed by introducing H2S gas, and the puri-fied acidic wastewater was used to dissolve ZnO for preparation of valuable ZnSO4middotH2O. The total economic benefit of resource recovery is estimated to be 11.54 $/m 3 . Accordingly, this study provides a new route for the resource recovery of the treatment of copper-containing acidic wastewater.(c) 2022 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V.