Methods for Testing the Steel Corrosion Inhibition in Alcohol-Gasoline Blends Using Diethylenetriamine

Alcohol-gasoline blends (AGBs) are fuels with higher corrosion aggressiveness than conventional petroleum-based fuels containing only hydrocarbons. Thus, the further use of AGBs is associated with finding a way to reduce these corrosion effects. The reduction of material corrosion can be achieved using corrosion inhibitors. In this work, we investigated the inhibitory effects of diethylenetriamine (DETA) in contaminated alcohol-gasoline fuel containing 85 vol % of butanol (B85). E85 fuel containing 85 vol % of ethanol was used for comparison as an alternative fuel. These fuels were purposely contaminated with water and trace amounts of chloride and sulfate ions, as well as acetic and sulfuric acids. The testing was performed on mild steel as this kind of steel has been used as the most common construction material for fuel transportation and storage. Corrosion tests were performed using (i) electrochemical impedance spectroscopy in two- and three-electrode arrangements, (ii) polarization curve measurements, (iii) cyclic potentiodynamic polarization, and (iv) static immersion tests. The DETA inhibitor efficiency in the most aggressive fuel was found to be 99%. With the use of the DETA inhibitor, a reduction in the corrosion current density was achieved from the initial value of 1.6 to 1.0 x 10(-2) mu A center dot cm(-2).