Felix-Balderrama, Sandra. M.S., Department of Chemistry, Wright State University,2009. Comparison of the Electrochemical Properties of Ethanol in Perchloric Acid and Ionic Liquids.
1-Ethyl-3-Methylimidazolium Tetrafluroborate (EMImBF4) and 1-Ethyl-3-
Methylimidazlium Bis(trifluoromethanesulfonyl)imide (EMImTFSI) ionic liquids were
synthesized and characterized in order to study the electrochemical oxidation of ethanol in these ionic liquids on a platinum surface electrode.
It was found that pure EMImBF4 exhibits an electrochemical window of 4.4 V,while EMImTFSI exhibits an electrochemical window of 5.0 V.
Electrochemical study of ethanol in perchloric acid showed that the oxidation of
ethanol strongly depends on the concentration of ethanol and on the temperature of the solution. The poisoning of the platinum electrode only depends on the concentration of ethanol. At a low concentration of ethanol (0.1 M), electro-oxidation of ethanol on a platinum electrode showed one oxidation peak (peak 2) at a temperature of 22.6 °C and two oxidation peaks (peak 2 and 3) at 70.1 °C. It was found that, with increasing temperature from 22.6 to 70.1 °C, the cyclic voltammograms showed an increase in oxidation. Electrochemical studies of ethanol at higher concentration of ethanol (> 0.2 M), showed three oxidation peaks. The poisoning of the electrode occurred at 1 M ethanol solution via formation of PtO.
The electrochemical studies of ethanol in EMImTFSI and EMImBF4 ionic liquids showed that poisoning of the electrode does not occur even at higher concentration of ethanol. It was proved that oxidation of ethanol in ionic liquids produces acetaldehyde and acetic acid.