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- Title
Dissolution and Solubility of the (Ba<sub>x</sub>Sr<sub>1-x</sub>)HAsO<sub>4</sub>⋅H<sub>2</sub>O Solid Solution in Aqueous Solution at 25°C and pH 2.
- Authors
Xuehong Zhang; Yinian Zhu; Caichun Wei; Zongqiang Zhu; Zongning Li
- Abstract
Six different members of the (BaxSr1-x)HAsO4⋅H2O solid solution were prepared and characterized, and then dissolution of the synthetic solids was studied at 25°C and pH 2 in a series of batch experiments for 4320 h. With the increase in the Ba/(Ba + Sr) mole fraction of the solids, the aqueous pH decreased and the aqueous barium concentration increased. The aqueous strontium and arsenic concentrations had the highest values at Ba/(Ba + Sr) = 0.21. The solubility products for BaHAsO4⋅H2O and SrHAsO4⋅ H2O were calculated to be 10-5.52 and 104.62, respectively. The corresponding free energies of formation were determined to be -1543.99 ± 0.18kJ/mol and -1537.94 ± 0.02kJ/mol. The solid solution had a minimum solubility product of 105.61 at Ba/(Ba + Sr) = 0.82. The Guggenheim coefficients were determined to be a0 = 1.55 and a1 = -4.35. The Lippmann diagram was a typical Lippmann diagram for a nonideal solid solution with a negative enthalpy of mixing. The system shows an "alyotropic" minimum at the aqueous Ba/(Ba+Sr) activity fraction of 0.87 where the solutus and solidus curves meet. At the end of the dissolution experiment, the dissolution followed the saturation curve for the pure endmember BaHAsO4⋅H2O and approached the intersection with the minimum stoichiometric saturation curve on the Lippmann diagram.
- Publication
Journal of Chemistry, 2014, p1
- ISSN
2090-9063
- Publication type
Academic Journal
- DOI
10.1155/2014/654168