Electrochemical and Theoretical Investigation for the Protection of Aluminum Corrosion in Hydrochloric Acid using Some Azole Derivatives

Three compounds of azole derivatives were investigated as inhibitors for the dissolution of aluminum (Al) in 0.5 M HCl solution using electrochemical techniques, e.g., potentiodynamic polarization, electrochemical impedance spectroscopy electrochemical frequency modulation (EFM). The surface of Al was examined in the absence and presence of the some azole derivatives using scanning electron microscopy (SEM). The potentiodynamic polarization suggests that these compounds act as mixed type inhibitors because they enhance both the anodic and cathodic Tafel slopes. The inhibition efficiency (%IE), increased with increasing the concentration of inhibitors. SEM proved the surface of Al is improved due to the adsorption of the azole compounds on the surface of Al. The adsorption of the azole compounds on the Al surface is obeyed Frumkin isotherm. The sequence of the %IE increases in the following order 1,2,3-benztriazole > methyl imidazole > imidazole. The extent of inhibition depends on the molecular size of the molecule and the electron density of the substituent groups.