Leucas Martinicensis as an Inhibitor of Carbon Steel Corrosion in Acidic Medium

Abstract

The inhibitory potentials of aqueous leave extract of Leucas Martinicensis (LM) for the corrosion of carbon steel in 1 M HCl solution was studied using gravimetric method, electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and scanning electron microscopy (SEM). The effect of temperature on the corrosion rate and inhibition efficiency was investigated, and some thermodynamic parameters were calculated. The result of the study revealed that the extract act as a potent inhibitor on carbon steel in the acid medium. The corrosion inhibition efficiency increases with increase in concentration and decreases with temperature. Maximum inhibition efficiency of 97 % was achieved at 250 ppm LM in 1M HCl and 303 K temperature. The potentiodynamic studies revealed that investigated LM extract act as mixed type inhibitor. Inhibitor adsorption characteristics were approximated by Langmuir adsorption isotherm at all the concentrations and temperatures studied. The result of SEM analysis was found to be consistent with the gravimetric and electrochemical results.