Electrochemical and theoretical investigation of the inhibitory effect of two Schiff bases of benzaldehyde for the corrosion of aluminium in hydrochloric acid

The corrosion inhibition effect of o-Aminophenol-N-Benzylidene (o-AmphNB) and o-Anisidene-N-Benzylidene (o  -AnsNB) for pure Aluminium in 1 M HCl at different concentrations of two different inhibitors were investigated by means of weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The values of ΔGadso revealed that the adsorption mechanism of these molecules on aluminium surface is competitive phenomenon between chemical and physical adsorption. Potentiodynamic polarization parameters revealed the mixed mode of inhibition with predominance of cathodic inhibition. The impedance results showed that with increase in concentration of inhibitor, charge transfer resistance increases while double layer capacitance decreases. Quantum chemical calculations based on density functional theory (DFT) method were performed on o-AmphNB and o-AnsNB to determine the relationship between molecular structures and their inhibition efficiencies. Correlation analysis concluded that the inhibition effect of inhibitors could be explained in terms of electronic properties.