Corrosion Protection of Carbon Steel in Hydrochloric Acid Solutions using Heterocyclic Compounds

The role of some heterocyclic compounds (1-3) as corrosion inhibitors for C- steel in 1 M HCl have been studied using weight loss, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and electrochemical frequency modulation (EFM) techniques. Polarization studies showed that all the compounds studied are mixed type inhibitors. The effect of temperature on corrosion inhibition has been studied and the thermodynamic activation and adsorption parameters were calculated and discussed. Electrochemical impedance was used to investigate the mechanism of corrosion inhibition. The presence of these compounds in the solution decreases the double layer capacitance and increases the charge transfer resistance. The adsorption of these compounds on C-steel surface was found to obey Temkin’s adsorption isotherm. The morphology of inhibited and uninhibited C- steel was analyzed by scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDX).