A Study on the Ternary Systems Li+, K+/SO42--H2O and Li+, Mg2+/SO42--H2O at 25 degrees C

Solubilities of the ternary systems Li+, K+/SO42--H2O (1) and Li+, Mg2+/SO42--H2O (2) were investigated by isothermal method at 25 degrees C. Physico-chemical properties of solutions, such as density, refractive index, viscosity, conductivity, and pH, were determined. Phase diagram of the system (1) consists of three sollubility branches and three crystallization fields corresponding to K2SO4, LiKSO4, and Li2SO4 center dot H2O. LiKSO4 is an incongruent compound, and its transition point is 45.5 similar to 46.0 based on graphical estimate. No solid solution of LiKSO4 with Li2SO4 center dot H2O was found in the system. System (2) is of a simple eutonic type. Pitzer model of electrolyte solution was used to check the obtained solubilities. Data comparison gives good agreement, Physico-chemical properties of solutions, such as density, refractive index, viscosity, conductivity, pH, and X-ray diffraction, IR spectra, DTA of LiKSO4 were measured. Two equations were used to correlate density, refractive index with copmposition. Differences between measured and calculated values are less than 0.6% for density, 0.15% for the later.