Diphenolic Schiff bases as corrosion inhibitors for aluminium in 0.1 M HCl: Potentiodynamic polarisation and EQCM investigations

The effects of novel synthesised two Schiff bases on the corrosion of aluminium in 0.1 M HCl were investigated using potentiodynamic polarisation and electrochemical quartz crystal microbalance measurements. Results show that inhibition efficiencies increase with increase in inhibitor concentration. This reveals that the inhibition occurs through adsorption of the inhibitor molecules on the metal surface. Adsorption of these inhibitors follows Temkin adsorption isotherm. The correlation between the inhibitor performances and their molecular structures has been investigated using quantum chemical parameters obtained by MNDO (modified neglect of diatomic overlap) semi-empirical method. Calculated quantum chemical parameters indicate that Schiff bases adsorbed on aluminium surface by chemical mechanism.

► Diphenolic Schiff bases behave as efficient cathodic inhibitors for the corrosion of aluminium.
► The inhibition action is mainly due to their chemisorption on the aluminium surface.
► EQCM measures the resonant frequency, Δf, shift due to the mass of adsorbed species.
► Nature of the adsorbed protective layer depends on the molecular structure of Schiff bases.