ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 63, Number 5
JKCSEZ 63(5)
October 20, 2019 

Inhibition effects of cysteine(Cys), methionine(Met), and histidine(His) on the corrosion of cobalt were investigated in deaerated 0.5 M HCl and 0.5 M H2SO4 solution. All the inhibition efficiency (IE) in the amino acids for the cobalt corrosion depended on the mixed inhibition. However, IE in the solution of H2SO4 depended more on the anodic and in the solution of HCl on the cathodic inhibition. Amino acid adsorption process on cobalt surface in the solution can be explained by modified Langmuir isotherm. The molecules of histidine dissolved in both of the solution were physically adsorbed due to the electrostatic interaction between the surface of {Co-Cl-δ} and the {-NH3 +} or {-NH+=} of His. However the other cases of adsorption in this investigation can be explained by chemical adsorption between the empty d-orbital of Co and the lone pair of electron in S-atom in Cys and Met.