Schiff's bases derived from l-lysine and aromatic aldehydes as green corrosion inhibitors for mild steel: Experimental and theoretical studies

Three Schiff's bases (SBs) namely, 2-amino-6 (2-hydroxybenzelideneamino) hexanoic acid (SB-1), 2-amino-6-(4-methoxybenzelideneamino) hexanoic acid (SB-2) and 2-amino-6-((4-dimethylamino)benzylideneamino) hexanoic acid (SB-3) derived from lysine (amino acid) and three different aldehydes were synthesized and evaluated as corrosion inhibitors for mild steel in 1 M HCl solution using weight loss, electrochemical, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and atomic force microscopy methods. The results showed that inhibition efficiency increases with the increasing concentration. Among the studied SBs the SB-3 showed maximum inhibition efficiency of 95.6% at 400 mg L− 1 concentration. Potentiodynamic polarization study revealed that the investigated SBs act as cathodic type inhibitors. Adsorption of the SBs on mild steel surface obeys the Langmuir adsorption isotherms. The weight loss and electrochemical results were well supported by SEM, EDX and AFM analyses.