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Modeling the response of control-released ion-selective electrode and employing it for the study of permanganate oxidation kinetics

Abstract

Although polymeric membrane ion-selective electrodes (ISEs) based on outward ion fluxes have been found analytical useful, there is still a lack of theoretical framework for such detection system. In this work, we attempt to model the response of this kind of permanganate ISE and employing it to analyze the rapid MnO4−/H2O2 reaction. This is attributed to the H2O2 oxidation with MnO4− that is released from the inner solution to the membrane surface layer. Results show that the experimental data could be fitted well to the proposed model that is elucidated mathematically from view point of chemical kinetics. The second-order rate constant is determined at near neutral pH and is in agreement with acid dissociation law to give the specific value of 370 M−1s−1. The kinetic mechanism is then investigated by performing DFT calculation. By analysis of Mn-O bond length and HOMO orbital, it has been found that the studied redox system functions similarly as the so-called “hydrogen abstraction” mechanism with an energy barrier of 24.5 kcal mol−1. This is considered to be the first report on the simulation of MnO4− attack at O-H bond. On the basis of transition state theory and previous studies of MnO4− attack at C=C and C-H bonds, the relationship between experimental rate constant and computational energy barrier is finally constructed. The result indicates the validity of our proposed method and makes the control-released ISE a very promising platform for kinetics.

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Publication details

The article was received on 26 Nov 2017, accepted on 23 Dec 2017 and first published on 26 Dec 2017


Article type: Paper
DOI: 10.1039/C7AY02735D
Citation: Anal. Methods, 2017, Accepted Manuscript
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    Modeling the response of control-released ion-selective electrode and employing it for the study of permanganate oxidation kinetics

    D. Song, R. Liang, X. Jiang, H. Sun, F. Kong, B. Lv, Q. Fang and W. Qin, Anal. Methods, 2017, Accepted Manuscript , DOI: 10.1039/C7AY02735D

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