Selective Sequential Recovery of Zinc and Copper from Acid Mine Drainage
authors Passos, H; Cruz, B; Schaeffer, N; Patinha, C; da Silva, EF; Coutinho, JAP
nationality International
author keywords waste valorization; recovery; liquid-liquid extraction; ionic liquids; process design
abstract The observed imbalance between the unsustainable consumption of available natural metal resources and finite deposits makes the recovery and recycling of metals from metal-containing wastes an imperative. Here, ionic-liquid- based aqueous biphasic systems (IL-based ABSs) are proposed as an efficient alternative for selective metal recovery from real copper acid mine drainage (AMD) effluents. ABSs composed of different ILs and Na2SO4 were evaluated for Zn, Al, Cu, Co, and Ni extraction from both model solutions and AMD samples. It is shown that IL composed of thiocyanate anion ([SCN](-)) presented a remarkable ability to extract metals from AMD through the formation of stable metal complexes. The addition of NaSCN to ABSs composed of tetrabutylammonium chloride ([N-4444]CI) allowed to mimic the use of [SCN]-based IL with additional advantages: tunable metal selectivity by the concentration of [SCN](-) added to the ABS and a reduction in system cost and environmental impact. Furthermore, at the [SCN] -concentration range studied here, the formation of a hydrophobic salt composed of IL cations and metal complex anions is observed, which allows the selective extraction and recovery of transition metals in a single step. The IL-rich phase recyclability in three extraction cycles is demonstrated, showing the possibility to recover two times more Zn than with a single extraction cycle while using the same amount of IL and thiocyanate. Salt-rich phases were also recycled in a new IL-based ABS for the subsequent Cu extraction and recovery. These results allow the development of a sustainable process for the selective sequential recovery of transition metals from AMD.
issn 2168-0485
year published 2021
volume 9
issue 10
beginning page 3640
ending page 3650
digital object identifier (doi) 10.1021/acssuschemeng.0c07549
web of science category 11
subject category Chemistry, Multidisciplinary; Green & Sustainable Science & Technology; Engineering, Chemical
unique article identifier WOS:000630171400003
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journal impact factor 7.632
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