Abstract:

Inhibition performance as well as the growth and decay laws of films formed on Q235 steel in a saturated carbon dioxide salt solution of imidazoline and imidazoline with a thioureido group were investigated by polarization curve and electrochemical impedance spectroscopy (EIS) techniques. Results showed that both types of imidazoline derivative inhibitors were mix-type inhibitors which mainly inhibited anodic processes. At 85 ℃, the film formed in 40 mg·L -1 of the non-thioureido imidazoline inhibitor formed slowly and had poorer adsorption capability than the thioureido-containing imidazoline inhibitor. The non-thioureido imidazoline inhibitor also disrobed easily from the steel. The film of thioureido-containing imidazoline can auto-repair itself. It also had better adsorption and inhibition efficiency compared with the non-thioureido imidazoline inhibitor. The hydrolyzed imidazoline with a thioureido group has poor absorption capability and its film life and inhibition efficiency decreased compared with the thioureido-containing imidazoline inhibitor. In this paper electrochemical results are also explained using quantum chemistry analysis.

Key words: Molecular structure, Imidazoline inhibitor membrane, Polarization curve, Electrochemical impedance spectroscopy, Quantumchemistry