Protection of Metallic Copper from the Attack of Sulphuric Acid Using HDMMA, a Schiff Base Derived from l-Cysteine and 2-Hydroxy-1-naphthaldehyde

Amino acids and its Schiff bases have been recognized as green corrosion inhibitors mainly due to its non-toxic nature and biodegradable properties. Considering its unique nature and significant contribution in corrosion inhibition, studies were undertaken with a Schiff base derived from l-cysteine, HDMMA [(E)-2-((2-hydroxyl-4a,8a-dihydronaphthalene-1-yl)methyleneamino)-3-mercaptopropanoic acid] as corrosion inhibitor for metallic copper in 1.0 M sulphuric acid. Techniques such as electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (Tafel), basic computational calculations, and adsorption studies were employed in the present study. Results revealed that HDMMA offer attractive inhibition efficiency in lower and elevated temperatures. The inhibition effect advanced with the inhibitor concentration. However, with the increased temperature the inhibition efficiency showed a declining trend. The mechanism of the inhibition action is due to the adsorption of the inhibitor molecules on the metal surface which decrease the double layer capacitance and increase the polarization resistance.