Effect of corrosion products on the inhibitory performance of imidazolium ionic liquid toward carbon steel in CO2-saturated NaCl brine

Abstract

Carbon steel corrosion represents an intractable problem during oil and gas exploitation. An imidazolium-based ionic liquid, 1-dodecyl-3-methyl imidazolium hydrogen sulfate (abbreviated as DMIMHS), was used as a corrosion inhibitor for carbon steel in the CO2-saturated NaCl brine at 313 K in this study. The inhibitive effects and mechanisms of the pre-corroded product on the anti-corrosion behavior of DMIMHS were investigated by electrochemical measurements, surface characterizations, quantum calculation and molecular dynamics simulations. The results showed that DMIMHS had remarkable inhibition efficacy on freshly abraded steel, with a 94.46% inhibition efficiency in the presence of 30 mg/L DMIMHS, and corrosion products can slightly decelerate the corrosion behavior. More importantly, the addition of DMIMHS favored the remarkably enhanced inhibitive properties for carbon steel after pre-corroded, namely the corrosion resistance increased with the extension of corrosion time. According to the experimental results and theoretical calculations, the inhibitive mechanisms of DMIMHS toward carbon steel in the CO2-saturated NaCl brine were proposed.