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| Author(s): |
Elton Fabiano Sitta
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | São Carlos. |
| Institution: | Universidade de São Paulo (USP). Instituto de Química de São Carlos (IQSC/BT) |
| Defense date: | 2008-02-01 |
| Examining board members: |
Hamilton Brandão Varela de Albuquerque;
Antonio Carlos Dias Angelo;
David Mendez Soares
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| Advisor: | Hamilton Brandão Varela de Albuquerque |
| Abstract | |
In the present work were studied some nonlinear aspects of the catalytic oxidation of ethylene glycol (EG) on platinum electrodes in alkaline media (KOH). The system\'s dynamics was investigated by means of cyclic voltammetry, current and potential time series, and electrochemical impedance spectroscopy (EIS). The EIS results reveal the presence of a hidden negative differential resistance around the main voltammetric peak. Overall, the system was able to oscillate for several periods, displaying a myriad of dynamic states which includes harmonic, small and large amplitude, periods 2, 3, and 4, and mixed-mode oscillations, as well as period doubling transition to chaos. The concentration of both EG and KOH were found to play an essential role in the temporal patterns observed. The complexity of the periods increase with EG concentration resulting in 90% of the oscillating time devoted to chaotic patters when EG concentration is 1.6 M. The increment of the current density produces an opposite behavior of the patters: the higher the applied current the simpler the oscillatory dynamics. The influence of some products of partial EG oxidation was studied under different conditions and compared. The results of the changes in the oscillatory morphology are rationalized in terms of its eventual connection with reaction intermediates formed during the oxidation process that, in turn, depends on the alcohol concentration and on the current density. (AU) | |
| FAPESP's process: | 06/01088-5 - Electrooxidation of ethylene glycol on nickel: kinetics and dynamic instabilities |
| Grantee: | Elton Fabiano Sitta |
| Support Opportunities: | Scholarships in Brazil - Master |