Solubility and Pitzer's ionic parameters in the system H2O-NaCl-MgCl2

Abstract

The object of this work was to determine Pitzer's ionic parameters, θ and Ψ, for the mixed salt solution H2O-NaCl-MgCl2 at following temperatures: 273.15, 298.15, 356.15 and 378.15 K in ionic strength interval from 7 to 17.5 mol/kg, using Pitzer-Kim's ionic method. The Pitzer's ionic interaction parameters at all temperatures were evaluated on the bases of solubility data for the system H2O-NaCl-MgCl2, and criterion of diffusion equilibrium. The mean ionic activity coefficient of the NaCl in heterogeneous system, in which NaCl(c) was in equilibrium with saturated mixed solution H2O-NaCl-MgCl2, was obtained using solubility data and criterion of diffusion equilibrium. Temperature dependence of the obtained Pitzer's ionic interaction parameters θ and Ψ,in temperature range from 273.15 to 378.15 K, were described by the polynom of the forth and second order, respectively.