Extraction, characterization and anti-corrosion activity of Mentha pulegium oil: Weight loss, electrochemical, thermodynamic and surface studies

The corrosion inhibition of carbon steel in 1M HCl solution by Mentha pulegium oil was investigated using weight loss, potentiodynamic polarization and electrochemical impedance spectroscopic techniques (EIS). Surface characterization was performed using optical profiler images and AFM analysis. The effect of temperature on the corrosion behavior of carbon steel was studied in the range of 298-338 K. Inhibition efficiency of 81% was achieved with 3 mL/L of M. pulegium oil at 298 K. The adsorption of the inhibitor molecules on the steel surface obeys the Temkin adsorption isotherm and involves physical adsorption. The thermodynamic calculation results indicate strong interaction between inhibitor molecules and carbon steel surface. The polarization studies showed that the oil acts as mixed-type inhibitor with predominance cathodic. Double layer capacitance, (Cdl) decrease indicates that a layer was form indicating the formation of a surface film. This reflects that the inhibitor does retard the corrosion rate.