Licorice root extract as corrosion inhibitor for tin in sodium chloride solutions

The corrosion behavior of tin electrode in 0.6 M NaCl solution as well as the effect of addition aqueous extract of licorice root were investigated using potentiodynamic techniques. It was found that the inhibition efficiency increases as the concentration of extract is increased. The inhibitive action of the extract was interpreted in view of adsorption of the extract components at the tin surface. The results showed that the adsorption follows Freundlich adsorption isotherm. The negative value of free energy of adsorption suggests a spontaneous process. Moreover, the addition of licorice root extract increases the resistance of tin toward pitting corrosion.