Role of Some Benzohydrazide Derivatives as Corrosion Inhibitors for Carbon Steel in HCl Solution

Corrosion inhibition of carbon steel in 2 M HCl by some benzohydrazide derivatives (I-III) was studied using weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) techniques at 30°C.Polarization studies showed that all the investigated compounds are of mixed type inhibitors.Temperature studies revealed a decrease in efficiency with rise in temperature and corrosion activation energies increased in the presence of the hydrazide derivatives, probably implying that physical adsorption of cationic species may be responsible for the observed inhibition behavior.Electrochemical impedance studies showed that the presence of benzohydrazide derivatives decreases the double layer capacitance and increases the charge transfer resistance.The adsorption of these compounds on carbon steel surface was found to obey Temkin's adsorption isotherm.Synergistic effects increased the inhibition efficiency in the presence of halide additives namely KI and KBr.An inhibition mechanism was proposed in terms of strongly adsorption of inhibitor molecules on carbon steel surface.