Potentiodynamic and Quantum Studies of Some Amino Acids as Corrosion Inhibitors for Copper

A comparative study of different types of amino acids: proline, cysteine, phenyl alanine, alanine, hisitidine and glycine as inhibitors for copper corrosion in 8M phosphoric acid at different temperatures was carried out. Potentiodynamic polarization and rotation techniques were applied to study the metal corrosion behaviour in the absence and presence of different concentrations of theses inhibitors. The results reveal that amino acids have strongest inhibitive effects that provide good protection to copper surface against corrosion in acid solutions. Adsorption of amino acids on copper surface, in 8M phosphoric acid solution, follows Temkin adsorption isotherm model. The Delta G(ads). values were calculated and indicated physical adsorption. Quantum chemical parameters were calculated using semiempirical PM6 method to find a good correlation with the inhibition efficiency. A good correlation was found between the theoretical calculations and experimental observations.