Search

Abstract: Standard Gibbs free energies for transfer of actinyl ions (; z =2 or 1; An: U, Np, or Pu) between an aqueous solution and an organic solution were determined based on distribution method combined with voltammetry for ion transfer at the interface of two immiscible electrolyte solutions. The organic solutions examined were nitrobenzene, 1,2-dichloroethane, benzonitrile, acetophenone, and 2-nitrophenyl octyl ether. Irrespective of the type of organic solutions, of , and were nearly equal to each other and slightly larger than that of Mg2+. The of was extraordinary large compared with those of ordinary monovalent cations. The dependence of of on the type of organic solutions was similar to that of H+ or Mg2+. The of An3+ and An4+ were also discussed briefly. [Copyright &y& Elsevier]

Abstract: Densities of LiCl, NaCl, KCl, and CsCl in normal and heavy water solutions have been measured using a vibrating-tube densitometer with (1–2)·10−6 precision at T =(288.15, 298.15, and 308.15)K over a wide concentration range from (0.1 to 5) molal, m. Solvent isotope effects (IE) on apparent molar volumes, as well as both on solute- and solvent-partial molar volumes were evaluated to establish their trend with cationic size in a systematic way. With the exception of the LiCl, both the “normal” standard IEs, , and the “inverse” excess IEs of the solutes, , increase linearly with the electrostriction effect of the cations (1/r ion), while with increasing temperature and/or concentration, the excess effects become almost the same. In contrast to the solute excess IEs, which show linear m 1/2-dependence over the whole concentration range, except for LiCl, the “inverse” excess IEs of the solvent, , hardly change over the lower concentration range (, m ⩽1). However, with further increase of the concentration, these IEs significantly decrease. Individual ionic standard and excess volume contributions are derived and the results are discussed in terms of structural concepts of ionic hydration. [Copyright &y& Elsevier]

Abstract: Density and speed of sound measurements have been made on the systems containing the ionic liquid 1-n-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]) and some organic solvents having a wide range of dielectric constants. Similar studies have been carried out for tetrabutylammonium hexafluorophosphate ([TBA][PF6]), which has common anion ([PF6]−) with the studied ionic liquid. For the systems investigated, the apparent molar volumes and apparent molar isentropic compressibilities were determined and fitted to the Redlich–Mayer and the Pitzer equations from which the corresponding limiting values were obtained. These limiting values were used to obtain some information about ion–solvent interactions. Furthermore, using the ionic limiting apparent volume values for [TBA]+ from the literature and limiting apparent molar volume for the ionic liquid and [TBA][PF6] obtained in this work, the ionic limiting apparent molar volume values for the cation [BMIM]+ in different organic solvents were also estimated. [Copyright &y& Elsevier]