Solubility and antisolvent crystallization of lithium hydroxide monohydrate in various organic solvents.

The effect of various organic antisolvents on the solubility of lithium hydroxide monohydrate (LiOH·H2O) in water was systematically determined in order to obtain composition data for lithium hydroxide - water - antisolvent ternary systems. Based on these data, antisolvent crystallization of LiOH·H2O from a synthetic aqueous feed solution was investigated. A total of nine antisolvents were studied, including methanol, ethanol, acetone, 1-propanol, 2-propanol, 1,4-dioxane, 1,2-dimethoxyethane, acetonitrile and tetrahydrofuran (THF). LiOH·H2O showed high solubility in methanol and ethanol, and low solubility in 2-propanol, 1,4-dioxane and 1,2-dimethoxyethane aqueous solutions. The use of THF resulted in the formation of two liquid phases in all cases, while acetonitrile and 1-propanol also led to liquid phase separation at lower antisolvent mole fractions. In the acetone system, solvent decomposition was confirmed by 1H NMR, revealing aldol condensation. Crystallization of LiOH·H2O was confirmed for all antisolvents by X-ray diffraction (XRD) and thermogravimetric analysis (TGA). Among the tested solvents, 2-propanol was selected as the most promising antisolvent due to its favorable solubility behavior, environmental and human health profile, safety, and lower cost compared to 1,4-dioxane and 1,2-dimethoxyethane.