Speaker
Description
To enable a sustainable human presence on the Moon, it is essential to use local resources safely and economically to access strategic metals1. This study evaluates the potential of deep eutectic solvents (DESs) for dissolving and electrochemically extracting metals from lunar regolith simulant. Lunar regolith simulant, representing Lunar Mare Soil (LMS-1), is an abundant and easily accessible material on the Moon2. LMS-1 was dissolved in freshly prepared reline (ChCl:Urea) by mechanical stirring at 250 rpm for 10 h at 70 °C under an argon atmosphere. The solubility of the oxides was determined using inductively coupled plasma–optical emission spectrometry (ICP–OES). In reline, Al₂O₃ showed a solubility of 0.4 wt%, SiO₂ reached 0.98 wt%, Cr₂O₃ exhibited the highest solubility at 14.6 wt%, followed by FeOₜ at 2.27 wt% and MgO at 4.1 wt%. Electrochemical measurements and electrolysis experiments were carried out in the supernatant solution using a three-electrode system: gold (Au) as the working electrode, platinum (Pt) as the counter electrode, and a platinum wire (Pt, 2 mm diameter) as the quasi-reference electrode. The equilibrium potentials of the metals were measured and correlated with the order in which the metals should be deposited on the cathode. Electrochemical investigations using cyclic voltammetry and square-wave voltammetry evaluated a highly complex system involving multiple multivalent redox processes. Selective metal recovery was subsequently achieved by potentiostatic electrolysis by adjusting the electrode potential. At more positive deposition overpotentials, the deposit was composed mainly of Si, whereas Al, Cr, and Fe, along with Si, were electrodeposited at more negative potentials, demonstrating controlled potential-dependent metal separation. These results demonstrate the possibility of controlled and selective metal deposition directly from DES electrolytes.
Keywords: Choline Chloride-Urea, Silicon, Lunar Mare Soil, Electrodeposition
Acknowledgement: Research was supported by the Science Fund of the RS, #Grant No. 270, Applying advanced product intellectual properties and industrialization workflows to innovative fundamental research ideas in the area of rare earth electrochemical recovery –REMEDIS. V.S.C. and N.M.P. acknowledge the financial support from the Ministry of Science, Technological Development and Innovation of the RS (Contract No: 451-03-33/2026-03/200026).
References:
1. Maes, M.; Gibilaro, M.; Chamelot, P.; Chiron, C.; Chevrel, Pinet, P.C.; Massot, L.; Favier, J.J.; Planet. Space Sci., 2024, 242, 105854. https://doi.org/10.1016/j.pss.2024.105854.
2. Schwandt, C., Hamilton, J.A., Fray, D.J., Crawford, I.A., Planet. Space Sci., 2012, 74, 49–56. https://doi.org/10.1016/j.pss.2012.06.011.