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

ABSTRACT

In order to exploit the valuable feature brine resource with high concentrations of borate ions in the world, the solubilities and physicochemical properties (refractive index, density, viscosity and pH) for the reciprocal quaternary system (Na+, Ca2+//Cl-, borate - H2O) at 288.15 K were determined experimentally using the method of isothermal dissolution equilibrium. According to the experimental data, the dry-salt phase diagram and water-phase diagram and the diagram of physicochemical properties (refractive index, density, viscosity and pH) against J(B4O72-) in the solution were plotted. In the dry-salt phase diagram of the quaternary system at 288.15 K, there are two invariant points, five univariant curves, and four crystallization regions corresponding to gowerite (CaB6O10*5H2O), borax (Na2B4O7*10H2O), antarcticite (CaCl2*6H2O) and sodium chloride (NaCl). The area of crystallization region of CaB6O10*5H2O is the largest, which indicates that the solubility of gowerite in this system is the lowest and more easily to separate by crystallization, and the areas of crystallization regions of Na2B4O7*10H2O, NaCl and CaCl2*6H2O are decreased in turn. Neither double salt nor solid solution in this reciprocal system was found. The water-phase diagram of the system shows that the Janecke index values of J(H2O) were gradually changed with the increasing of J(B4O72-). The physicochemical properties of the quaternary system varied regularly with the increasing Janecke index values of J(B4O72-).