Inhibition of Silver Corrosion in Nitric Acid by Some Aliphatic Amines

The inhibition of silver corrosion in dilute nitric acid (0.01M) was studied using electrochemical polarization technique in the presence of different concentrations of methylamine, ethylamine, n-propylamine, and n-butylamine. It was found that the inhibition efficiency obtained from Tafel plots improved when the inhibitor concentration and the length of the alkyl chain were increased. The inhibition efficiency increased markedly with increase the additive concentrations according to the following order: methylamineethylaminen-propylaminen-butylamine. The inhibition action of such compounds occurred by simple blocking of amines on the electrode surface through adsorption process according to Temkin adsorption isotherm. The nearly constant values of the anodic Tafel slopes indicated that the presence of such amines do not affect the mechanism of metal dissolution.