Adsorption and corrosion inhibition behavior of Acanthus montanus leaves Extract on Mild Steel in Sulphuric acid Medium

The inhibitive action and mechanism of Acanthus montanus leaves extract (AMLE) for the corrosion of mild steel in 2M H2SO4 was investigated using gravimetric, Potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), Fourier transform infrared (FTIR), and Scanning electron microscope (SEM) techniques. It was found that the extract inhibits the acid induced corrosion of mild steel. The inhibition efficiency (%IE) was observed to increase with increasing extract concentration but decreased with rise in temperature. Maximum inhibition efficiency value of 75.7% was obtained at 0.5g/l from gravimetric measurement. Electrochemical measurements results showed that AMLE acted as a mixed-type inhibitor. The adsorption of AMLE on mild steel was physical and obeyed Langmuir adsorption isotherm model. Kinetic data followed a first-order reaction type. Results obtained from the gravimetric, potentiodynamic polarization and impedance measurements showed similar trends of inhibition efficiency. Surface analysis by FTIR and SEM confirmed the formation of protective layer on the mild steel surface.