Solubility and thermodynamic modeling of calcium sulfate dihydrate in three organic aqueous solutions (ethylene glycol, acetic acid, dimethyl sulfoxide) from 303.15 K to 348.15 K

• Solubility of DH in three organic aqueous solutions at 303.15 to 348.15 K. • Experimental solubility data was correlated by four thermodynamic models. • Thermodynamic properties of mixing process were investigated. In this work, for further study on solubility behaviors of calcium sulfate dihydrate (DH) in different organic aqueous solutions, solubility of calcium sulfate dihydrate (DH) in three binary solvents (water + ethylene glycol, acetic acid, dimethyl sulfoxide) was experimentally investigated by the dissolution equilibrium method at (303.15 to 348.15) K under 88.35 kPa. Solubility data of DH first increased and then decreased with the temperature increased while reduced with the increasing molality of organic solvents. Experimental solubility data was correlated by four thermodynamic models including Wilson, modified Apelblat-Jouyban-Acree, UNIQUAC and NRTL model, all of them can well correlate the solubility of DH. Besides, thermodynamic properties of mixing process (Δ mix G , Δ mix S , Δ mix H , H 1 E,∞ and lnγ 1 ∞ ) were investigated based on solubility data and the Wilson equation.