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 acidicwastewater.Firstly,the selective removal of Cu(II)fromactualwastewater 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.