Selective Sequential Recovery of Zinc and Copper from Acid Mine Drainage

The observed imbalance between the unsustainable consumption of available natural metal resources and finite deposits makes recovery recycling metals from metal-containing wastes an imperative. Here, ionic-liquid-based aqueous biphasic systems (IL-based ABSs) are proposed as efficient alternative for selective real copper acid mine drainage (AMD) effluents. ABSs composed different ILs Na?SO? were evaluated Zn, Al, Cu, Co, Ni extraction both model solutions AMD samples. It is shown that IL thiocyanate anion ([SCN]?) presented a remarkable ability to extract through formation stable complexes. addition NaSCN tetrabutylammonium chloride ([N????]Cl) allowed mimic use [SCN]-based with additional advantages: tunable selectivity by concentration [SCN]? added ABS reduction in system cost environmental impact. Furthermore, at range studied here, hydrophobic salt cations complex anions observed, which allows transition single step. IL-rich phase recyclability three cycles demonstrated, showing possibility recover two times more Zn than cycle while using same amount thiocyanate. Salt-rich phases also recycled new IL-based subsequent Cu recovery. These results allow development sustainable process sequential AMD.