Enhanced Inhibition of the Corrosion of Metallic Copper Exposed in Sulphuric Acid Through the Synergistic Interaction of Cysteine and Alanine: Electrochemical and Computational Studies

Abstract

Amino acids have been categorized as green corrosion inhibitors due to their unique properties such as non-toxic and biodegradable nature. Considering its great importance in corrosion chemistry, studies were undertaken with an objective to find out the interaction behaviour of amino acids such as cysteine and alanine on corrosion inhibition of copper in 1 M sulfuric acid at varying temperatures such as 303, 308 and 313 K. Various techniques such as weight loss method, electrochemical impedance spectroscopy, potentiodynamic polarization (Tafel), basic computational calculations and adsorption studies were employed in the present investigations. Results revealed the synergic interaction of amino acids cysteine and alanine with attractive corrosion inhibition efficiency in 1 M concentration of sulfuric acid. The inhibition effect of amino acid cluster advanced with the increased concentration of the inhibitor. However, with the increase in temperature, the inhibition efficiency showed a declining trend. Such behaviour of the amino acids on copper in sulfuric acid medium may be due to surface adsorption of the inhibitor molecules on the metal which contributes to decrease in the double layer capacitance and increase in the polarization resistance.