Solubility of Barium Sulfate in Water at Elevated Temperatures and Pressures

There are few measurements of barium sulfate (BaSO₄) solubility in water above 373 K available in the literature. BaSO₄ solubility data at water saturation pressure are scare. The pressure dependence on BaSO₄ solubility has not previously been comprehensively reported for the pressure range 100-350 bar. In this work, an experimental apparatus was designed and built to measure BaSO₄ solubility in aqueous solutions under high-pressure (HP), high-temperature (HT) conditions. The solubility of BaSO₄ was experimentally determined in pure water over the temperature range from T = (323.1 to 440.1) K and pressures ranging from p = (1 to 350) bar. Most of the measurements were done at water saturation pressure: six data points were done above the saturation pressure (323.1-373.1 K) and 10 experiments were conducted at water saturation (373.1-440.1 K). The reliability of the extended UNIQUAC model and results generated in this work was demonstrated by comparing with the scrutinized experimental data reported in the literature. The model gives a very good agreement with BaSO₄ equilibrium solubility data, demonstrating the reliability of the extended UNIQUAC model. The accuracy of the model at high temperature and saturated pressure due to data insufficiencies is discussed.