Corrosion Inhibition of Carbon Steel in Hydrochloric Acid Solution by Mentha Pulegium Extract

The inhibition effect of Mentha pulegium extract (MPE) on the acid corrosion of carbon steel in 1 M HCl solution was investigated using weight loss, potentiodynamic polarisation, and electrochemical impedance spectroscopy. The results show that the Mentha pulegium extract is a good inhibitor, and that the inhibition efficiency depends on the concentration of the plant extract. Efficiency is higher than 88 % for 33% Mentha pulegium extract. Polarization measurements also show that Mentha pulegium extract is a good mixed inhibitor. The remarkable inhibition efficiency of MPE was discussed in terms of blocking of the electrode surface by adsorption of inhibitor molecules through active centres. Mentha pulegium extract is adsorbed on the carbon steel surface according to the Temkin adsorption model. The effect of temperature on the corrosion behaviour of carbon steel in 1 M HCl with addition of 33% MPE was studied in the temperature range 308-338 K. SEM also confirmed the adsorption of MPE on carbon steel surface.