月と火星での建築に使用可能な溶剤が特定される(Potential solvents identified for building on moon and Mars)

2024-01-12

2024-01-11 ワシントン州立大学(WSU)

◆ワシントン州立大学の研究者は、機械学習と計算モデリングを駆使して、月や火星の岩塵から建築材料を抽出するための液体溶媒の候補を見つけた。
◆イオン液体と呼ばれるこれらの溶媒は、月や火星の材料を溶解し、重要な元素を抽出できる可能性があり、環境に優しくエネルギー効率が高い選択肢として注目されている。これにより、将来の宇宙旅行での材料の現地利用が可能になり、特に月のような水が利用できない環境での持続可能な採取方法が期待されている。

＜関連情報＞

レゴリスからの金属抽出に向けて：イオン液体中の金属イオンの溶媒和構造とダイナミクスの理論的研究 Toward Metal Extraction from Regolith: Theoretical Investigation of the Solvation Structure and Dynamics of Metal Ions in Ionic Liquids

Azmain F. Islam and Soumik Banerjee
Journal of Physical Chemistry B Published:November 9, 2023
DOI:https://doi.org/10.1021/acs.jpcb.3c04057

Abstract

Lunar and Martian regoliths, containing feldspar, pyroxene, ilmenite, olivine, and aluminite minerals, are excellent sources of metals such as aluminum, sodium, magnesium, and iron. Ionic liquids (ILs), which are excellent solvents with extremely low vapor pressure and high electrochemical stability, can be potentially leveraged for extracting metals from regolith in an extra-terrestrial environment. A critical step in the solvation process, which determines the effectiveness of the IL solvent, is the formation of solvation shells around the metal cations. To determine the rigidity and stability of the solvation shells, which has a direct implication on the extraction of metals, we performed classical molecular dynamics simulations of dilute solutions comprising individual metal ions Na⁺, Mg²⁺, and Al³⁺ in two distinct ILs, [mppy][TFSI] and [mppy][HSO₄]. Our results indicate that the compactness of the structure is directly related to the charge density of the metal cation and the relative size and symmetry of the IL anion. Potentials of the mean force of the metal cation with the solvating IL anion indicate the presence of energy minima with barriers that increase with the surface charge density of the cation. The increasing energy barrier leads to greater residence time of metal cations in the solvation shell, which was confirmed by evaluating corresponding autocorrelation functions. Overall, our calculations provide fundamental insights into key factors that influence the solvation of metals and can be useful in the screening of ILs for digestion of metal-containing minerals in lunar and Martian regoliths.