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Electrochemical Investigation for Cu 2+ Oscillatory Phenomena at the Liquid/Liquid Interface with a Specific Adsorption of Ion Pair Model
Author(s) -
Zhang Yijun,
Bu Caihong,
Wang Yongcheng,
Wang Zhihua,
Lu Xiaoquan,
Liu Xiuhui
Publication year - 2012
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/elan.201200170
Subject(s) - oscillation (cell signaling) , chronoamperometry , ion , adsorption , aqueous two phase system , aqueous solution , electrochemistry , current (fluid) , phase (matter) , chemistry , cyclic voltammetry , chemical physics , analytical chemistry (journal) , liquid liquid , voltammetry , electrode , thermodynamics , chromatography , organic chemistry , biochemistry , physics
In this paper, a novel current oscillatory phenomenon for Cu 2+ at the water/1,2‐dichloroethane interface is reported with cyclic voltammetry and potential‐step chronoamperometry. The small irregular current spikes were only observed near the site of the oxidation peak of CuCl 2 − and were mainly related to the Cu 2+ concentration in the aqueous phase. Our experimental results demonstrated that the current oscillation is caused by specific adsorption of ion pairs at the W/DCE interface between Cu 2+ in the aqueous phase and TPB − in the organic phase. Therefore, a specific adsorption of ion pair model has been formulated for the current oscillation at the liquid/liquid interface. The DFT calculation method was used to explain the mechanism of ion pair formation. The calculation results suggested that the TPB − Cu 2+ TPB − ion pair has the lowest‐energy state, thus providing qualitative support for the ion pair model. A probable mechanism for the observed current oscillation was also discussed in this paper. At the same time, a spectrophotometric experiment was performed to evidence a strong attractive interaction between Cu 2+ and TPB − .