Isoindoline derivatives as inhibitors for the corrosion of carbon steel in HCl solution

The corrosion inhibition of carbon steel in 2.0 M HCl solution by four isoindoline derivatives has been investigated using weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. Tafel polarization showed that these derivatives are mixed-type inhibitors. The inhibition efficiency was found to increase with increasing concentration of inhibitor and decreases with increasing temperature. The Logarithmic isotherm was found to provide an accurate description of adsorption behavior of the isoindoline derivatives. Some thermodynamic parameters were computed and discussed. Synergistic study revealed that, the investigated anions (I−, Br− and SCN−) may enhance adsorption of the inhibitors. The variation in inhibition efficiency depends on the type of functional group substituted in benzene ring. It was found that the presence of donating group (such as CH3) better facilitates the adsorption of molecules on the surface than in the case with withdrawing groups (such as −H, −Br, and NO2). The data obtained from the three different methods are in good agreement.