Inhibitive of methanol extract of Pennyroyal Mint (Mentha pulegium) on the corrosion of mild steel in HCl

The inhibitive action of methanol extract of Pennyroyal Mint (Mentha pulegium) (EMPR) on corrosion of mild steel in 1.0 M HCl solution was investigated by weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy. The adsorption of EMPR on mild steel follows a Langmuir adsorption isotherm, and the activation parameters governing the adsorption process were calculated and discussed. Polarization measurements reveal that the EMPR acts as a mixed-type inhibitor. Electrochemical impedance spectroscopy results showed that the corrosion and corrosion inhibition of steel occurred mainly by charge transfer. The inhibition efficiencies obtained from weight loss measurements and electrochemical tests were in good agreement.