Synergistic effect of amino acids and chloride ion on adsorption On copper metal

Abstract

The effect of adsorption of a- alanine, P-alanine, DL-aspartic, L-glutamine, iso-leucine and L-lysine in 1 M HC1 solution on the corrosion of copper has been studied using the potentiokinetic technique. The examined amino acids inhibited the corrosion of copper at all examined concentrations, but L-lysine accelerated the corrosion rate. The corrosion rates of copper were measured as a function of concentrations. The degree of surface coverage as calculated from the corrosion rate is used to calculate the free energy of adsorption of the amino acids. The variation of the free energy of adsorption with surface coverage is interpreted in terms of change in the mechanism of inhibition of amino acids with concentration. The synergistic effect of amino acids and chloride ions is discussed from the viewpoint of adsorption models. The inhibitive action requires a knowledge of inhibitor at the electrode-solution interface. Adsorption isotherm of the inhibitors for the corrosion process have been discussed.