Corrosion inhibition of 1018 carbon steel in hydrochloric acid solutions by benzothazol-2-cyanomethyl derivatives

The corrosion behavior of 1018 carbon steel in 0.5 M HCl solution in the absence and presence some benzothazol-2-cyanomethyl derivatives was investigated using weight loss, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and electrochemical frequency modulation (EFM) techniques. The results obtained from these techniques show that, the inhibition efficiency of these inhibitors increased with increase in inhibitor concentration but deceased with rise in temperature. Adsorption of these derivatives follows the Temkin adsorption isotherm. The polarization measurement showed that these inhibitors are acting as mixed-type inhibitors for both anodic and cathodic reactions. Some activated thermodynamic parameters were computed and discussed. The results obtained from the four different techniques were in good agreement. Quantum structure-activity relationships have been used to study the effect of molecular structure on inhibition efficiency of the inhibitors.