The solubility of barite and celestite in sodium sulfate: Evaluation of thermodynamic data

Applying a Thermodynamic Model to the Non‐Stoichiometric Precipitation of Barium Sulfate

“…(10) yields the concentration of complexes in a saturated solution. The equilibrium constant K IP can be estimated experimentally, and the following two values at 25 C have been reported: log(K IP ) = ±2.72 [6], and log(K IP ) = ±2.26 [7]. Based on the considerations above, the equilibrium composition of BaSO 4 -solutions can be calculated using two different approaches, namely by accounting either for the presence of ions only, i.e.…”

“…3 of [10]). These functions were parameterized for aqueous Ba 2+ /SO 4 2± /Na + /Cl ± -solutions using experimental data obtained at a concentration as large as 6 M [6,7]. In addition to the activity coefficient models above, it should be considered that BaSO 4 does not behave like a strong electrolyte that dissociates completely in water, but rather forms undissociated ion-pairs (complexes) through the following reaction [6,7]:…”

“…Activity coefficients were calculated using the Bromley model, Eq. (6), and the Pitzer model, Eqs. (7) and (8), using log(K SP ) = ±10.05 for the solubility product [7].…”

“…The Bromley model, Eq. (6), and the Pitzer model, Eqs. (7) and (8), were used to determine activity coefficients, and in both cases complex formation was considered.…”

Combined experimental/numerical study on the precipitation of nanoparticles

“…For the equilibrium constant for the formation of the barium sulfate ion-pair complex, a value of K ip ϭ 1.91 ϫ 10 Ϫ3 kmol/m 3 can be found in Felmy et al (1990) and a value of K ip ϭ 5.4 ϫ 10 Ϫ3 kmol/m 3 can be found in Monnin (1999), both assuming that the activity coefficient for neutral species such as the ion-pair complex are close to unity. For consistency with the solubility product, the value by Monnin is used further on.…”