Study of the inhibition of corrosion of mild steel in a 1M HCl solution by a new quaternary ammonium surfactant

The anticorrosive effect of surfactant, 12-(2,3-dioxoindolin-1-yl)-N,N,N-trimethyldodecanammonium bromide 3 on the corrosion of mild steel in 1M hydrochloric acid was assessed by gravimetric and electrochemical techniques (potentiodynamic polarization and electrochemical impedance spectroscopy). The results have shown that our synthesized surfactant is an excellent corrosion inhibitor for mild steel in 1 M HCl. Inhibitory efficacy of up to 95.9% was exhibited by surfactant 3 at a concentration of 1 mM after 6 h immersion at 298K. Based on the polarization curves, it is clear that the surfactant 3 can be considered as a mixed inhibitor with a predominantly anodic character. The inhibitory effectiveness increases with increasing concentration but decreases with increasing temperature. It was found that the adsorption of the inhibitor on the surface of the mild steel in 1M HCl followed the Langmuir adsorption isotherm. In this context, the main kinetic and thermodynamic parameters were determined and discussed.