Evaluating performance of malva sylvestris leaf extract for protection of mild steel against corrosion in acidic solution

In this study, Malva sylvestris (M. sylvestris) leaf extract was evaluated for the protection surface of the mild steel in 2.0 M HCl solution. For this purpose, the classical method of weight loss and electrochemical methods potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) were used in the first step to assess the performance of the extract. The results showed that, by changing the concentration of the extract from 0.25 g/L to 2.0 g/L in 2.0 M HCl solution, percent inhibition increased from 47% to 93% (for the concentration of 2.0 g/L). In addition, no significant change in the percentage of inhibition was observed as the concentration of the extract exceeded 2.0 g/L. The effect of the temperature on the behavior of the extract, for concentrations of 0.25, 0.5, 1.0, 1.5, and 2.0 g/L, at 35, 45, 55, and, 65 °C, were also investigated using polarization method. The percentage of inhibition and coverage were calculated to obtaining the kinetic parameters. The results revealed that, the absorption of molecules of the extract on the surface of the steel obeyed from the Langmuir adsorption isotherm and it was a physical adsorption type.