Ionic Liquid Parameter Prediction Leveraging Quantum Structure Property Relationships

U.S. Space Exploration Policy denotes the critical importance of establishing an outpost on the Moon to provide the foundation for human missions beyond cislunar space. However, launching spare components and systems from Earth will likely be cost prohibitive, so the single most important development that is required for enhancing, and in some cases enabling, sustained human presence on the Lunar surface is having the capability to extract metals, oxygen, and water from the Lunar regolith. Ionic Liquids (ILs) are noteworthy for their host of unique chemical properties: a relatively large temperature range in the liquid phase, negligible vapor pressures, thermal and chemical stability, wide voltage window, and many have low toxicity. Furthermore, their coupled organic and ionic nature make them excellent solvents for a wide range of materials. In particular, acidic ionic liquids show the potential to enhance oxygen and metals production from regolith via dissolution and electrolysis. Furthermore, given their organic composition, the physical and chemical properties of ILs can be fine-tuned by modifying their ion structures and combination. Relative abundance changes with sample location, but the principal metals of interest for In Situ Resource Utilization (ISRU) in the Lunar regolith are iron, aluminum, magnesium, calcium, and titanium. However, an IL has yet to be identified that reliably dissolves titanium dioxide or silicon dioxide. Manufacturing and testing even a relatively small subset of the million theoretically stable IL anion/cation combinations for mineral digestion performance analysis is time and cost prohibitive. This paper will discuss a software process pipeline and corresponding analysis setpoints for a method to determine quantum structure property relationships (QSPR), which relate IL molecular structure to chemical function. Using QSPR, hundreds or even thousands of ILs could be assessed for efficacy in regolith ISRU and beyond.