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Mechanism and rate of anomalous extraction of chloride salts from water to 1,2-dichloroethane
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SYSNO ASEP 0587478 Document Type J - Journal Article R&D Document Type Journal Article Subsidiary J Článek ve WOS Title Mechanism and rate of anomalous extraction of chloride salts from water to 1,2-dichloroethane Author(s) Trojánek, Antonín (UFCH-W) RID
Samec, Zdeněk (UFCH-W) RID, ORCID
Fiedler, Jan (UFCH-W) RID, ORCID
Mareček, Vladimír (UFCH-W) RIDArticle number 144642 Source Title Electrochimica acta. - : Elsevier - ISSN 0013-4686
Roč. 498, SEP 2024 (2024)Number of pages 9 s. Language eng - English Country GB - United Kingdom Keywords anomalous salt extraction ; electrochemical measurements ; IT spectroscopy Subject RIV CG - Electrochemistry OECD category Electrochemistry (dry cells, batteries, fuel cells, corrosion metals, electrolysis) R&D Projects GA22-32631S GA ČR - Czech Science Foundation (CSF) Method of publishing Limited access Institutional support UFCH-W - RVO:61388955 UT WOS 001267414700001 EID SCOPUS 85197652311 DOI https://doi.org/10.1016/j.electacta.2024.144642 Annotation Open circuit potential (OCP) measurements, potentiostatic pulse (PP) amperometry and cyclic voltammetry (CV), were used to investigate and to sort by rate the anomalous extraction of the chloride salts RCl of the cations R+ = tetrabutylammonium (TBA+), tetrapentylammonium (TPeA+), tetrahexylammonium (THexA+), tetraheptylammonium (THepA+) and bis(triphenyl-phosphoranylidene)ammonium (BA+) from water to 1,2-dichloroethane (DCE). A tentative mechanism is proposed comprising (a) the diffusion-controlled transport of the ion-pairs (RCl)ip from the aqueous to the organic solvent phase providing a major contribution to the chloride extraction, (b) decomposition of the multiple ion-pairs or clusters (RCl)ipx, which are formed by agglomeration of the single ion-pairs (RCl)ip in the aqueous phase (w), and (c) the exponential decay of the ion-pairs (RCl)ip accumulated on the organic solvent side of the interface at the beginning of the OCP measurements. This model enables to simulate successfully the experimental time dependence of the chloride concentration. A conclusion is made that the effect of the composition of the organic solvent electrolyte RX, where X- = tetraphenylborate (TPB-) or tetrakis(pentafluorophenyl) borate (TB-), on the rate and extent of the anomalous accumulation of the chloride anion in the phase (o) of the two-phase liquid system LiCl(w)/RX(o) can be related to the hydrophobicity of the electrolytes RCl and RX. The latter property can be characterized by the standard Gibbs energy of transfer from the aqueous (w) to the organic solvent (o) phase. The accumulation of the chloride anion in the phase (o) appears to be promoted by the decreasing value of the transfer Gibbs energy of RCl in the sequence TBACl > TPeACl > THexACl > THepACl > BACl, while the decreasing value of the transfer Gibbs energy of RX in the sequence TBATPB > TPeATPB > THexATPB > THepATPB > BATPB > BATB starts to block the cycle combining the energetically unfavorable extraction of RX from the phase (o) to the phase (w) with the energetically favorable extraction of RCl in the opposite direction. IR spectroscopy provides evidence of the formation of the water clusters in the organic solvent phase equilibrated with the aqueous phase in the presence of the tetraalkylammonium cation in both phases, which are supposed to drive the anomalous accumulation of the chloride anion in the phase (o). Workplace J. Heyrovsky Institute of Physical Chemistry Contact Michaela Knapová, michaela.knapova@jh-inst.cas.cz, Tel.: 266 053 196 Year of Publishing 2025 Electronic address https://www.sciencedirect.com/science/article/pii/S001346862400882X
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