Theoretical and experimental studies for corrosion inhibition performance of Q235 steel by imidazoline inhibitors against CO₂ corrosion

The inhibition performance of two imidazoline inhibitors, 1-(2-thioureaethyl)-2-alkyl-imidazoline (TAI) and chloride-1-(2,3- dihydroxylpropyl)-1-(2-thioureaethyl)-2-alkyl-imidazoline sodium phosphate (TAIP), for Q235 steel in saltwater saturated with CO₂ was studied by using molecular dynamics simulations and quantum chemistry calculations. The conclusions were experimentally verified by weight loss, polarization curves, electrochemical impedance spectroscopy (EIS) and surface analysis techniques. The theoretical results suggest that imidazoline ring and heteroatoms are the active site and the adsorption stability weakens gradually in the order of TAIP, TAI. Experimental results show that the two inhibitors act as mixed type inhibitors and can inhibit the corrosion of Q235 in CO₂ saturated saltwater solution.