Study of the influence of new quinoxaline derivatives on corrosion inhibition of mild steel in hydrochloric acidic medium

The effect of a new corrosion inhibitors, namely 3,7-dimethylquinoxalin-2 (1H)-one (DMQ=O) and 3,7-dimethylquinoxalin-2 (1H)-thione (DMQ=S), on corrosion of mild steel in 1 M HCl was investigated by weight loss measurement and various electrochemical techniques. Results obtained reveal that all the compounds perform excellently as corrosion inhibitors for mild steel in acidic media. Potentiodynamic polarization studies have shown that all these compounds slow down both the anodic and cathodic processes and then act mixed-type inhibitors. Double layer capacitance and charge transfer resistance values were derived from Nyquist plots. Changes in impedance parameters are indicative of adsorption of these compounds on the metal surface. The inhibition efficiency mainly depends on the nature of the investigated compounds. The adsorption of these compounds on mild steel surface is found to obey Langmuir adsorption isotherm.