Ana R. F. CARREIRA1, Helena PASSOS1, Nicolas SCHAEFFER1, Lenka SVECOVA2, Nicolas PAPAICONOMOU3, Isabelle BILLARD2, João A. P. COUTINHO1
1University of Aveiro, Aveiro, Portugal
2Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, Grenoble INP (Institute of Engineering and Management Univ. Grenoble Alpes), LEPMI, Grenoble, France
3Université Co?te d’Azur, CNRS, Institut de Chimie de Nice, UMR 7272 , Nice, France
Urban mining is a sustainable and cost-effective methodology for metal recovery from alternative sources, such as electrical and electronic equipment waste. Metal recovery from wastes usually involves a multi-metallic solution. Ionic liquids (ILs) are versatile solvents suitable for metal extraction. Acidic aqueous biphasic systems (AcABS) are alternative liquid-liquid extraction systems composed of two water-rich immiscible phases. Unlike aqueous biphasic systems, in AcABS the salt is substituted by an acid. Still, the mechanism of metal extraction is currently not well known due to the novelty of IL-based AcABS. Herein, AcABS based on tributyltetradecyl-ILs were applied for metal recovery of Co(II), Cu(II), Mn(II), Ni(II) and Ce(IV) in multi-metallic solutions. The effect of several parameters on metal extraction was evaluated, including metal concentration, IL anion, acid, and acid concentration. Acid played an important role in metal extraction. The free energy of hydration of the metal complex and the anion/water ratio were linked to the metal's extraction efficiency. The selectivity of the developed AcABS was optimized by adjusting temperature, ionic strength, and acid concentration.
Acknowledgments: This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020, UIDP/50011/2020 & LA/P/0006/2020, financed by national funds through the FCT/MEC (PIDDAC). Ana R. F. Carreira acknowledges FCT for the Ph.D. grant SFRH/BD/143612/2019. H. Passos acknowledges FCT – Fundação para a Ciência e a Tecnologia, I.P. for the researcher contract CEECIND/00831/2017, under the Scientific Employment Stimulus - Individual Call 2017.