Thermodynamic Solubility Constant of Ca(OH)2 in Simulated Radioactive Sulfate Liquid Waste

The thermodynamic solubility product constant ( K _sp) of Ca(OH)₂ in simulated radioactive sulfate liquid waste was experimentally determined at temperatures of 25° and 40°C. Synthetic solutions were prepared with pH ranging from 12.6 to >14 and ionic strength ranging from 0.25 M to 3.7 M . All the solutions were saturated in CaO and contained Na₂SO₄ to simulate the salts accompanying radioactive liquid waste. The Bromley model was applied to estimate the global ionic activity coefficients, and the K _sp value was compared with those found in the literature. The stability ranges of the different compounds formed as a function of pH were determined by X-ray diffractometry analysis, and their quantification was conducted by thermal analysis.