Anisidines as Corrosion Inhibitors for Zinc in Phosphoric Acid

Abstract

The corrosion of zinc in phosphoric acid has been studied at different acid concentrations, inhibitor concentrations and temperatures. Corrosion rate increases with the concentration of acid and the temperature. The inhibition efficiency (IE) of anisidines increases with the concentration of inhibitor. The inhibition efficiency decreases with the increase in concentration of acid. At 80 mM inhibitor concentration in 0.01 M H3PO4 acid at 301 K for 24 h immersion period, the inhibition efficiency decreases in the order: m-anisidine (98.7 %) > o-anisidine (97.3 %) > panisidine (96.0 %). As temperature increases, percentage of inhibition decreases. The plot of  versus log C results in a straight line which suggests that the inhibitors cover both the anodic and cathodic regions through general adsorption following Langmuir isotherm. Galvanostatic polarization curves show the polarization of both the anode as well as cathode.