TY - JOUR
T1 - Thermodynamics and physical properties of an ionic liquid-based metal extraction process
AU - Othman, Enas A.
AU - van der Ham, Aloijsius G.J.
AU - Miedema, Henk
AU - Kersten, Sascha R.A.
N1 - Publisher Copyright:
© 2024
PY - 2024/6
Y1 - 2024/6
N2 - In this study a LLX process for the extraction of cobalt by the IL [P8888][Oleate] is analysed in terms of relevant thermodynamic parameters. The process can be considered a typical example of transition metal extraction by an ionic liquid. Conductivity and chemical (FTIR) analyses indicate that Co2+ complexes with the IL. Three different models are evaluated, all different with respect to the actual Co2+ species that complexes with the IL, as well as the Co2+:IL stoichiometry. Based on simulations we identified CoCl2 as the Co species that enters and complexes with the IL, in a Co2+:IL ratio of 1:2. The complexation reaction between the Co-species and the IL is an endothermic, entropy-driven reaction. The influence of the feed composition on Co2+ extraction is investigated, including the effect of the nature of the accompanying anion as well as the presence of a salting out cation agent. The higher Co2+ extraction from a NO3− medium is due to the stronger interaction between Co(NO3)2 and the IL, reflected by a higher equilibrium constant of Co(NO3)2 compared to CoCl2. Differences in dehydration enthalpy between the ion species involved may contribute as well. Similar effects play a role when comparing uptake rates in solutions containing both Co2+ and Na+, with Co2+ extraction clearly preferred over that of Na+. Observed differences in Co2+ uptake in the presence of a salting-out agent (NaCl, KCl and NH4Cl) can be explained in terms of the hydration energy of the salting out cation, the higher this hydration energy, the higher the Co2+ uptake by the IL.
AB - In this study a LLX process for the extraction of cobalt by the IL [P8888][Oleate] is analysed in terms of relevant thermodynamic parameters. The process can be considered a typical example of transition metal extraction by an ionic liquid. Conductivity and chemical (FTIR) analyses indicate that Co2+ complexes with the IL. Three different models are evaluated, all different with respect to the actual Co2+ species that complexes with the IL, as well as the Co2+:IL stoichiometry. Based on simulations we identified CoCl2 as the Co species that enters and complexes with the IL, in a Co2+:IL ratio of 1:2. The complexation reaction between the Co-species and the IL is an endothermic, entropy-driven reaction. The influence of the feed composition on Co2+ extraction is investigated, including the effect of the nature of the accompanying anion as well as the presence of a salting out cation agent. The higher Co2+ extraction from a NO3− medium is due to the stronger interaction between Co(NO3)2 and the IL, reflected by a higher equilibrium constant of Co(NO3)2 compared to CoCl2. Differences in dehydration enthalpy between the ion species involved may contribute as well. Similar effects play a role when comparing uptake rates in solutions containing both Co2+ and Na+, with Co2+ extraction clearly preferred over that of Na+. Observed differences in Co2+ uptake in the presence of a salting-out agent (NaCl, KCl and NH4Cl) can be explained in terms of the hydration energy of the salting out cation, the higher this hydration energy, the higher the Co2+ uptake by the IL.
KW - UT-Gold-D
KW - Ionic liquids
KW - Metal extraction
KW - Salting out agent
KW - Solvent extraction
KW - Statistical analysis
KW - Thermodynamics
KW - Hydration energy
UR - http://www.scopus.com/inward/record.url?scp=85192681384&partnerID=8YFLogxK
U2 - 10.1016/j.jil.2024.100097
DO - 10.1016/j.jil.2024.100097
M3 - Article
AN - SCOPUS:85192681384
SN - 2772-4220
VL - 4
JO - Journal of Ionic Liquids
JF - Journal of Ionic Liquids
IS - 1
M1 - 100097
ER -