Protic ionic liquid 2HEABu addition effect in a 0.01 mol.L~(-1) NaCl solution on the API 5L X70 steel corrosion inhibition

摘要

The aim of this paper is to study the addition effect of protic ionic liquid 2-hydroxiethylammonium butanoate (2HEABu) in a 0.01 mol.L~(-1) NaCl solution, on the API 5L X70 steel corrosion inhibition. 2HEABu was used because, in former works, it presented inhibitor corrosion behaviour in aqueous medium. To evaluate the electrochemical performance, 500 mg.L~(-1) of 2HEABu was added in a 0.01 mol.L~(-1) NaCl solution. The samples were characterized by open circuit potential monitoring, potentiodynamic polarization and electrochemical impedance spectroscopy, in different immersion times (1, 5, 24 and 48 hours). The obtained results showed that the presence of 2HEABu shifted the corrosion potential towards higher values until approximately 5 hours of immersion. Until this immersion time, the samples were not significantly attacked in comparison to the ones in contact with sodium chloride solution. Polarization results showed, until 1 hour of immersion, the formation of a passive behaviour, possibly associated to the PIL adsorption onto the metallic substrate. However, the oxide resistance values obtained by EIS for both studied systems were in the same order of magnitude which indicates that the PIL addition in the concentration used was not effective for the corrosion protection of the substrate after 5 hours of immersion.