Liquid Equilibrium in the Ternary MgBr2-MgSO4-H2O System at 348.15 K and Its Application

The solid-liquid equilibrium of the ternary MgBr2-MgSO4-H2O system at 348.15 K was explored by using the isothermal equilibrium method, intending to realize the comprehensive utilization of the basic magnesium bromide (MgBrOH) waste residue produced in maltol production. It was observed that the phase diagram was composed of four single-salt crystallization regions, four univariate solubility curves, three invariant points saturated with MgSO4 center dot 6H(2)O + MgSO4 center dot 4H(2)O, MgSO4 center dot 4H(2)O + MgSO4 center dot H2O, and MgSO4 center dot H2O + MgBr2 center dot 6H(2)O, respectively, and three corresponding cocrystallization zones. Neither double salts nor a solid solution appears. The ion- interaction parameters at 348.15 K were determined using the Pitzer model, which were proven effective on this system. The calculated and experimental solubilities are coincident essentially. Based on the obtained phase diagram, a new technological process for the extraction of MgSO4 and MgBr2 from MgBrOH was proposed, and the purity of MgBr2 product was up to 99.65%. The MgBrOH waste residue produced from maltol production would achieve further development and create more benefits.

Automated summary

The solid-liquid equilibrium of the ternary MgBr2-MgSO4-H2O system at 348.15 K was explored, revealing the composition and characteristics of the phase diagram, leading to a new technological process for the extraction of MgSO4 and MgBr2 from MgBrOH.