Solubility predictions for the reciprocal quaternary system (NaCl + MgCl2 + Na2SO4 + MgSO4 + H2O) at 283.15 K using Pitzer ion-interaction model

摘要

Solubilities of the reciprocal quaternary system (Na + Mg + Cl + SO4 + H2O) at 283.15K were calculated using Pitzer ion-interaction model and its extended HW model. On the basis of the temperature-dependent equation produced by Spencer-M⊘ller-Weare, the values of the Pitzer single-salt parameters β⁽⁰⁾, β⁽¹⁾, β⁽²⁾ and C^ϕ for NaCl, MgCl2, Na2SO4, and MgSO4, the mixed ion-interaction parameters θNa, Mg, θCl, SO4, ψNa, Mg, Cl, ψNa, Mg, SO4, ψNa, Cl, SO4 and ψMg, Cl, SO4, and the Debye-Hückel parameter A^ϕ in the quaternary system at 283.15K were fitted. Based on the Jänecke indexes, the phase diagram was plotted. A comparison of the calculated and experimental results shows that the predicted solubilities agree well with the experimental values. This study affords the necessary parameters for solubility predictions of complicated systems and establishes a theoretical basis for the separation of these valuable minerals from salt lake brine.