Abstract Corrosion inhibition potential of Terminalia catappa (TC) leaves for zinc in HNO3 medium was studied using weight loss, Fourier Transform Infra-Red (FTIR) and scanning electron microscopy. The corrosion inhibition mechanism of the plant extract on the zinc surface in 0.1 M HNO3 acid at different temperatures (303 – 333K) show that the inhibition efficiency (IE) increases with increase in concentration of the inhibitor but decreases with increase in temperature throughout the test period, indicating a physisorption of extract on the zinc surface. The inhibited and uninhibited corrosion reaction of zinc in HNO3 medium was found to be spontaneous, first order, exothermic and occurred with increasing degree of order. The adsorption characteristic of the inhibitor was best described by the Langmuir adsorption isotherm. Scanning electron microscopy results indicated that the inhibitor formed a protective cover on the surface of the metal and thereby inhibited its corrosion. While the results from the FTIR study showed that some functional groups of the inhibitor may have been used in the formation of bonds and adsorption layer between Zn and the inhibitor which indicates that there is interaction between the inhibitor and the studied metal.
Keywords Terminalia catappa, Zinc, Corrosion inhibition, Adsorption.