Solubility of rare earth chlorides in ternarywater-salt systems in the presence of a fullerenol-C60(OH)24 Nanoclusters at 25 °C. models of nonelectrolyte solubility in electrolyte solutions


Charykov N.A. Keskinov V.A. Tsvetkov K.A. Kanbar A. Semenov K.N. Gerasimova L.V. Shaimardanov Z.K. Shaimardanova B.K. Kulenova N.A.
February 2021MDPI AG

Processes
2021#9Issue 21 - 20 pp.

The solubility in triple water-salt systems containing NdCl3, PrCl3, YCl3, TbCl3 chlorides, and water-soluble fullerenol C60(OH)24 at 25 °C was studied by isothermal saturation in ampoules. The analysis for the content of rare earth elements was carried out by atomic absorption spectroscopy, for the content of fullerenol-by electronic spectrophotometry. The solubility diagrams in all four ternary systems are simple eutonic, both consisting of two branches, corresponding to the crystallization of fullerenol crystal-hydrate and rare earth chloride crystal-hydrates, and containing one nonvariant point corresponding to the saturation of both solid phases. On the long branches of C60(OH)24*18H2O crystallization, a C60(OH)24 decreases by more than 2 orders of magnitude compared to the solubility of fullerenol in pure water (salting-out effect). On very short branches of crystallization of NdCl3*6H2O, PrCl3*7H2O, YCl3*6H2O, and TbCl3*6H2O, the salting-in effect is clearly observed, and the solubility of all four chlorides increases markedly. The four diagrams cannot be correctly approximated by the simple one-term Sechenov equation (SE-1), and very accurately approximated by the three-term modified Sechenov equation (SEM-3). Both equations for the calculation of nonelectrolyte solubility in electrolyte solutions (SE-1 and SEM-3 models) are obtained, using Pitzer model of virial decomposition of excess Gibbs energy of electrolyte solution. It is shown that semi-empirical equations of SE-1 and SEM-3 models may be extended to the systems with crystallization of crystal-solvates.

Atomic absorption spectroscopy , Chlorides of rare earth elements , Electron spectrophotometry , Eutonics , Fullerenol , Isothermal saturation in ampoules , Modified sechenov equation , Salting-out , Saltingin effects , Solubility

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Department of Physical Chemistry, Saint-Petersburg State Technological Institute, Technical University, 26, Moskovskii Prospekt, Saint-Petersburg, 190013, Russian Federation
Department of Physical Chemistry, Saint-Pretersburg Electrotechnical University (LETI), 5 Professora Popova Str, Saint-Petersburg, 197376, Russian Federation
Department of Chemistry, Pavlov First Saint Petersburg State Medical University, L’va Tolstogo Str. 6-8, Saint Petersburg, 197022, Russian Federation
Mining and Metallurgical Department, East Kazakhstan State Technical University, 69, A.K. Protozanov Street, Ust-Kamenogorsk, 070004, Kazakhstan

Department of Physical Chemistry
Department of Physical Chemistry
Department of Chemistry
Mining and Metallurgical Department

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