Effect of water solubility in organic solvents on the standard Gibbs energy of ion transfer across a water/organic solvent interface

0570455 - ÚFCH JH 2024 RIV GB eng J - Journal Article
Trojánek, Antonín - Mareček, Vladimír - Langmaier, Jan - Samec, Zdeněk
Effect of water solubility in organic solvents on the standard Gibbs energy of ion transfer across a water/organic solvent interface.
Electrochimica acta. Roč. 449, MAY 2023 (2023), č. článku 142222. ISSN 0013-4686. E-ISSN 1873-3859
R&D Projects: GA ČR(CZ) GA22-32631S
Institutional support: RVO:61388955
Keywords : Ion transfer voltammetry * Alkali metal and proton cations * Standard Gibbs energy of ion transfer * Solubility of water * Born-type model of ion solvation
OECD category: Electrochemistry (dry cells, batteries, fuel cells, corrosion metals, electrolysis)
Impact factor: 6.6, year: 2022
Method of publishing: Limited access

Ion transfer voltammetry is used to study the transfer of alkali metal and proton cations and the Cl- anion from the aqueous solution of MCl (M+ = H+, Li+, Na+, K+, Rb+, Cs+) to the solution of bis(triphenylphosphor-anylidene)ammonium tetrakis(pentafluorophenyl)borate in alpha,alpha.alpha-trifluorotoluene (TFT) or 1,2-dichloroethane (DCE). The scale of the applied potentials is converted to the scale of the Galvani potential differences on the basis of the voltammetric measurements of the standard ion transfer potential for the tetraethylammonium (TEA+) ion used as a reference ion in situ. The interfacial tension measurements at the water/TFT interface yield the zero-charge potential difference, which is close to the expected zero value. The standard Gibbs energies of ion transfer Delta owG0i are evaluated from the voltammetric data on considering both the effect of the association between the transferred ion and the counter-ion of the organic solvent phase, and the effect of the ion migration in the aqueous phase. The values of Delta owG0i for the ion transfer to TFT are found to be considerably higher than those obtained for the ion transfer to DCE. This difference is proposed to be related to the significantly lower solubility of water in TFT, possibly requiring the removal of the ion hydration shell in the course of the ion transfer from water to TFT. Such conclusion is supported by the calculations of Delta owG0i by using an advanced Born-type model of ion solvation.
Permanent Link: https://hdl.handle.net/11104/0341746