Thermodynamic evaluation of lithium recovery and freshwater production by sustainable hydrate-based desalination from brine solutions

초록

The increasing global demand for lithium, a critical component in energy storage technologies, necessitates the development of sustainable recovery methods from diverse aqueous resources. In this study, we investigate a hydrate-based desalination (HBD) process utilizing chlorodifluoromethane (R22) gas as a hydrate former to simultaneously achieve lithium recovery and freshwater production from lithium-containing brines. Thermodynamic phase equilibrium experiments, synchrotron X-ray diffraction, Raman spectroscopy, and solid-state nuclear magnetic resonance confirm that lithium ions are excluded from the hydrate cages, whereas R22 molecules occupy the large cages of structure I hydrates. The effect of LiCl and Li2SO4 concentrations on hydrate formation kinetics was examined, revealing a significant dependence on subcooling temperature and salt concentrations. Furthermore, the thermodynamic correlation functions accurately predict the hydrate equilibrium shifts by lithium salts and the ideal maximum freshwater production ratio, highlighting its potential use for HBD process optimization. These findings demonstrate the feasibility of R22 HBD as a scalable strategy for sustainable lithium recovery and freshwater production from lithium-containing brines.

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