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 dimethyldithiocarbamate (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°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 recovery for strongly acidic wastewater. Firstly, the selective removal of Cu(II) from actual wastewater using Zn(DMDC) 2 , with a removal efficiency of 99.7%. Secondly, high-value CuO was recovered by calcining the Cu(DMDC) 2 at 800°C, with a copper recovery efficiency of 98.3%. Moreover, the residual As(III) and Cd(II) were removed by introducing H 2 S gas, and the purified acidic wastewater was used to dissolve ZnO for preparation of valuable ZnSO 4 ·H 2 O. 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.