Thermodynamic model for the solubility of Ba(SeO4, SO4) precipitates
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Dhanpat Rai
,
Andrew R. Felmy
Abstract
The solubility of Ba(SeO4, SO4) precipitates was determined as a function of the BaSeO4 mole fractions, ranging from 0.0015 to 0.3830, and time with an equilibration period extending to as long as 302 days. Equilibrium/steady state conditions in this system are reached in ≤ 65 days. Pitzer's ion interaction model was used to calculate solid and aqueous phase activity coefficients. Thermodynamic analyses showed that the data do not satisfy Gibbs-Duhem equation, thereby demonstrating that a single-solid solution phase does not control both the selenate and sulfate concentrations. Our extensive data with log 10 [Ba] ranging from − 3.6 to −5.9 mol kg–1, log 10 [SeO4] ranging from − 3.6 to −5.2 mol kg–1, and log 10 [SO4] ranging from − 4.0 to −5.3 mol kg–1 can be explained with the formation of an ideal BaSeO4 solid solution phase that controls the selenium concentrations and a slightly disordered/less-crystalline BaSO4(s) (log 10K○sp =− 9.5 instead of − 10.05 for barite) that controls the sulfate concentrations. In these experiments the BaSO4 component of the solid solution phase never reaches thermodynamic equilibrium with the aqueous phase. Thermodynamic interpretations of the data show that both the ideal BaSeO4 solid solution phase and less-crystalline BaSO4(s) phase are in equilibrium with each other in the entire range of BaSeO4 mole fractions investigated in this study.
©2014 Walter de Gruyter Berlin/Boston
Articles in the same Issue
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Articles in the same Issue
- Frontmatter
- Excitation functions and yields for cyclotron production of radiorhenium via deuteron irradiation: natW(d,xn)181,182(A+B),183,184(m+g),186gRe nuclear reactions and tests on the production of 186gRe using enriched 186W
- A route for polonium 210 production from alpha-particle irradiated bismuth-209 target
- High accuracy plutonium mass determination by controlled-potential coulometry
- Chemometric approach for prediction of uranium pathways in the soil
- Thermodynamic model for the solubility of Ba(SeO4, SO4) precipitates
- Suitability of various materials for porous filters in diffusion experiments
- Detoxification of azinophos methyl using gamma radiation mediated advance oxidation process and investigation of degradation products by HPLC and GC-MS
- Investigation of elemental and radiological contamination of soils in two shipyards in Chittagong, Bangladesh
- Radionuclide content and state of isotopic disequilibrium in some utilized smoking pastes
- Assessment of natural radioactivity in major building materials of Xiangyang, China
