Thermodynamics Research Center / ThermoML | Journal of Chemical and Engineering Data

ABSTRACT

Solubilities, densities, refractive indices and pH values of the ternary systems (LiCl + LiB5O8 + H2O) and (Li2SO4 + LiB5O8 + H2O) at 288.15 K and 101 kPa were studied using the isothermal dissolution method and the wet-residue method. From the experimental data, the phase diagrams and the diagrams on physicochemical properties including density, refractive index and pH value against composition were plotted. The results show that two systems belong to simple saturation type, and no double salt or solid solution formed at 288.15 K. For the two systems, there are both in one invariant point, two isothermal dissolution curves and two crystallization regions including lithium pentaborate pentahydrate (LiB5O8*5H2O, Lb5), lithium chloride dehydrate (LiCl*2H2O, Lc2, in the former) and lithium sulfate monohydrate (Li2SO4*H2O, Ls1, in the latter). It was found that the area of the crystallization region of Lb5 was larger than that of Lc2 in the former system and Ls1 in the later system, and the results indicated that the solubility of lithium pentaborate was lower in the two systems. The densities and refractive indices in the two ternary systems at 288.15 K increased firstly and then decreased with the increase of LiCl and Li2SO4 concentration in the solution. However, the pH values present a contrary trend, which decreased firstly and then increased. The calculated values of density and refractive index using empirical equations for the two ternary systems agree well with the experimental values.