Solubility of Rare Earth Chlorides in Ternary Water-Salt Systems in the Presence of a Fullerenol—C60(OH)24 Nanoclusters at 25 °C. Models of Nonelectrolyte Solubility in Electrolyte Solutions

Abstract

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.

Directed assembly of fullerenols via electrostatic and coordination interactions to fabricate diverse and water-soluble metal cation–fullerene nanocluster complexes

“…Keskinov et al explained the very strong salting-out effect in fullerenol-D-LaCl 3 -H 2 O ternary system at very low concentrations of fullerenols near eutonic points, where rare earth salt served as a highly-effective salting-out agent. 27,28 Nevertheless, their results did not clarify whether the sediment could be further re-dissolved in deionized water. In our case, it is incomprehensible that the dissolution of the sediment from LaCl 3 cannot be observed in 2 mL deionized water in comparison to treatments in Fig.…”

“…24 Some investigations mentioned the salting out of fullerenols in the cosaturated fullerenol-saltwater ternary systems in the presence of varied inorganic salts to result in precipitates of fullerenols. [25][26][27][28][29] However, the roles of salts were largely unclear on whether metal ions-induced the further assembly of fullerenols via coordination or not. The rst direct evidence about metal ions coordinating to fullerenols was revealed by Anderson et al, where fullerenols acted as a ligand analogous to a 1,2-diol or catechol to possibly form tetrahedral and octahedral coordination under the stoichiometric condition of fullerenols to metal ions excess of 1 : 10.…”

Innovative Approaches for Improving the Quality and Resilience of Spring Barley Seeds: The Role of Nanotechnology and Phytopathological Analysis

“…All investigated nanopreparations with a complex of useful functions on the basis of fullerenes for treatment of crops with the purpose of providing the increase of efficiency and controllability of agricultural production were developed with the participation of the authors of this article. A number of articles [14][15][16][17] are devoted directly to the synthesis and identification of fullerenols.…”