Investigation of the Inhibitive Effect of 2-(Ethylthio)-1,4,5-Triphenyl-1H-Imidazole on Corrosion of Steel in 1 M HCl

The influence of 2-(ethyllthio)-1,4,5-triphenyl-1H-imidazole(DNSO) on the corrosion of mild steel in 1M HCl solution has been studied by weight loss measurements, potentiodynamic polarizations and electrochemical impedance spectroscopy (EIS). The inhibiting action increases with the concentration of the tested inhibitor. The highest efficiency 91% is obtained at 3.10-3 of DNSO. We note good agreement between gravimetric and electrochemical methods (potentiodynamic polarisation and EIS). Data, obtained from EIS measurements, were analyzed to model the corrosion inhibition process through appropriate equivalent circuit model; a constant phase element (CPE) has been used. Polarization measurements show also that DNSO act as good mixed inhibitor. DNSO is adsorbed on the steel surface according to a Langmuir isotherm adsorption model.