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Prediction and Measurement of Gypsum Solubility in the Systems CaSO4 + HMSO4 + H2SO4 + H2O (HM = Cu, Zn, Ni, Mn) at 298.15 K

Wang, Wenlei, Zeng, Dewen, Yin, Xia, Chen, Qiyuan
Industrial & Engineering Chemistry Research 2012 v.51 no.14 pp. 5124-5134
calcium sulfate, copper, copper sulfate, engineering, gypsum, heavy metals, manganese, manganese sulfate, models, nickel, physical phases, prediction, solubility, sulfuric acid, thermodynamics, water activity, zinc, zinc sulfate
Solubility of gypsum in the quaternary systems CaSO₄–HMSO₄–H₂SO₄–H₂O (HM = Cu, Zn, Ni, Mn) are predicted up to saturated concentrations of heavy metal sulfates and to a H₂SO₄ concentration of 2 m by a Pitzer thermodynamic model. Experimental solubility and water activity in the subbinary and subternary systems from the literature were used for model parametrization. Then the solubility phase diagrams for the quaternary systems were predicted directly with these obtained binary and ternary model parameters. In order to verify the reliability of the predicted results, a series of solubility measurements of gypsum in these quaternary systems have been carried out at 298.15 K and the measured results were compared with the predicted ones. It was shown that the Pitzer thermodynamic model can perfectly predict the solubilities of gypsum in the quaternary systems. Meanwhile, the newly obtained experimental data were compared with limited literature data in some of the quaternary systems; good agreement was found between them. Some application examples were given based on the predicted phase diagrams.