Electrochemical study on corrosion inhibition of iron in acidic medium by Moringaoleifera extract

Abstract

The aim of this work is to investigate corrosion inhibition characteristics of steel (X70) in chlohydric acid (1M) in presence of different concentration (1-60 cm3) of Moringaoleifera extract using potentiodynamic polarization studies and impedance measurements. The inhibition efficiency increased with increasing Moringaoleiferaextract concentration; the low concentration 0.25% V/V was chosen since the inhibition efficiency of the extracts was generally very high. The experimental data showed that the inhibition performance for Tafel and the impedance are 65-70% and 40-55% respectively; maximum inhibition could reach about 84-86% at the concentration of 15% V/V. The results obtained from electrochemical impedance spectroscopy showed that the variation in the impedance parameters, charge transfer resistance and double layer capacitance, with the variation in extract concentration is due to the adsorption of active molecules leading to the formation of a protective layer on the surface of carbon steel. The strong adsorption mechanism between the extract and the mild steel substrate is found to obey Langmuir's, Temkin's and Frumkin's isotherms. All data presented in the present paper suggest that the Moringaoleifera plant has high inhibition efficiency in acid media.