Density, viscosity, refractive index and electrical conductivity of saturated solutions of the lithium hydroxide + ethanol + water system at 298.15 K, and thermodynamic description of the solid-liquid equilibrium

The water + ethanol + lithium hydroxide system has a great potential for implementing drowning-out crystallization processes in industrial lithium hydroxide production. For this reason, a knowledge of both the most relevant physical properties as well as the thermodynamic description of the solid-liquid equilibrium of this system is of great interest for designing industrial applications. In this paper, the density, viscosity, refractive index and electrical conductivity of the saturated solutions of water + ethanol + lithium hydroxide at 298.15 K were measured for different mass fractions of ethanol/solution in a range from 0 to 0.6. Equations are given for the values of the measured properties as a function of the mass fraction of ethanol. The phase diagram at 298.15 K was determined and its regions were illustrated. Under our experimental conditions, the precipitated salt was, in all cases, LiOH·H2O. Finally, a thermodynamic description of the solid-liquid equilibrium of the ternary system is provided based on the Chen model for calculating the mean ionic activity coefficients. This approach requires nine binary interaction parameters for a ternary system. Here, only the three binary interaction parameters corresponding to the LiOH + ethanol system were fitted, while the six remaining parameters (those corresponding to the water + ethanol and LiOH + water systems, respectively) were taken from previous published values.