Chemija / Chemistry
 ISSN 0235-7216 ISSN 2424-4538 (online) |
2015 m. Nr. 3 Influence of gasoline hydrocarbons on electrochemical processes during steel corrosion in ethanol
Although corrosion mechanisms in ethanol have been discussed extensively, conclusions cannot always be extended to bioethanol and gasoline mixtures. In the presence of water, phase separation can take place leading to rapid corrosion on the bottom of reservoirs, tanks, lines, etc. In this study electrochemical experiments were developed to investigate the corrosion mechanisms on horizontally immersed low carbon steel electrodes. The electrolytes represented simulated biofuels with 100, 85, 70% and 33% vol. of dehydrated ethanol plus 1:1 mixture of n-heptane and toluene with or without addition of water, acetic acid and chlorides. Electrodes were laid into flasks with simulated biofuels and periodically removed to measure Electrochemical Impedance Spectroscopy (EIS) parameters. Counterintuitively, the corrosion accelerated with higher amounts of hydrocarbons most likely due to two main factors. Although electrochemical behaviour of blends with 15% hydrocarbons or less was similar to that of pure ethanol, hydrocarbon increase to 30% produced a big change in kinetics. Another factor could be minor amounts of water, which might lead to phase separation and preferential adsorption of water aggregates on horizontal metal surfaces. The phase separation could intensify in the presence of chlorides. If amounts of hydrocarbon and ethanol are similar in biofuel, great care must be taken to prevent the access of chlorides and other corrosion precursors.
Keywords: corrosion, ethanol, electrochemistry, fuel |
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