Experimental and computational insights into sustainable lithium recovery and freshwater production via CO2 hydrate-based desalination

The growing demand for lithium, a critical resource for the renewable energy and electric vehicle industries, necessitates the development of innovative recovery technologies to ensure a sustainable supply of diverse lithium resources. In this study, we propose a CO2 hydrate-based desalination (HBD) process as a sustainable solution for lithium recovery and freshwater production from lithium-containing brines. Thermodynamic stability of CO2 hydrates under varying concentrations of LiCl and Li2SO4 was experimentally investigated to provide essential insight into optimizing the CO2 HBD process. Utilizing a combination of synchrotron X-ray diffraction, Raman, and solid-state nuclear magnetic resonance spectroscopy, we confirmed the formation of a structure I hydrate capturing CO2 and the exclusion of Li+ ions from the hydrate cages, thus providing dual benefits of HBD: lithium recovery and freshwater production. Kinetic experiments involving CO2 hydrate in the presence of lithium salts revealed the strong influence of the sub-cooling temperature and the lithium salt concentration on the formation kinetics. Molecular dynamics simulation analyses allowed us to gain molecular-level insights into how the hydrate formation can be inhibited by Li+ ions, causing their exclusion from the hydrate cages. This study highlights the potential of the HBD process to offer a sustainable and scalable pathway to meet the global demand for lithium recovery and to address the issue of freshwater scarcity.