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

ABSTRACT

To understand the thermodynamic behaviors of the borate containing system, the solid-liquid equilibrium data (solubilities, density, and refractive index) of quinary aqueous solution composed of lithium, potassium, rubidium, magnesium, and borate at 323.15 K were determined by using the isothermal dissolution method. The crystalloid forms of the solid phase were confirmed by the X-ray diffraction method. Results show that four single salts Li2B4O7*3H2O, K2B4O7*4H2O, RbB5O8*4H2O, and MgB4O7*9H2O formed at 323.15 K in the quinary invariant point, no double salt or solid solution was found. Under the condition of Li2B4O7 saturation, the crystallization region of MgB4O7*9H2O occupied the largest crystallization region, and salt K2B4O7*4H2O had the smallest region. Among the four salts, the salts MgB4O7*9H2O and RbB5O8*4H2O crystalline regions changed obviously at 323.15 and 348.15 K, the crystalline region of MgB4O7*9H2O enlarged at 323.15 K, and that of RbB5O8*4H2O and K2B4O7*4H2O decreased.