Ethanol Extract of Curcuma longa as a green corrosion inhibitor for carbon steel in solution of HCl

Abstract

 Ifeoma Okonkwo, *Gloria Chika Udeokpote and Uduak Bassey Essien

Investigation of the potential of ethanol extract of Mango leaf as a green corrosion inhibitor for the corrosion of carbon steel was implemented using gravimetric, FTIR and scanning electron microscopy analytical techniques. Results obtained from the gravimetric analysis indicated that the inhibition efficiency of the extract were 57.38, 72.13 and 78.69% at the inhibitor’s concentration of 0.1, 0.2 and 0.3g/L of the extract respectively. The corrosion and the corrosion inhibition process were found to followed pseudo first order kinetics and at various concentrations, the inhibitor demonstrated the potential to extend the halflife of the metal in the acid solution. The adsorption of the inhibitor suited the Langmuir and Frumkin adsorption models. The inference drawn from the isotherms revealed that there exists an interaction between the inhibitor’s molecules and that the
lateral interaction parameter revealed the attractive behaviour of the inhibitor. The adsorption was spontaneous and agreed with
the mechanism of physical adsorption. The scanning electron micrograph of the metal surface after inhibition revealed the formation of a protective layer on the metal surface. Some functional groups that were native to the leaf extract were found to be missing in the FTIR spectrum of corrosion product which suggested that they were used for adsorption while some were shifted, an indication that there was an interaction between the adsorbed species.