Corrosion Inhibition of l-Methionine Amino Acid as a Green Corrosion Inhibitor for Stainless Steel in the H2SO4 Solution

This study investigated the effect of l-methionine (LMT) on the corrosion behavior of AISI309S stainless steel in 1 M H2SO4 solution using electrochemical impedance spectroscopy (EIS), Tafel polarization, and electrochemical noise methods. The performance of corrosion inhibition was analyzed by scanning electron microscopy, atomic force microscopy, adsorption isotherms, x-ray photoelectron spectroscopy (XPS), and contact angle measurement. The electrochemical studies revealed a significant increase in the charge transfer resistance and a reduction in the corrosion current density in the presence of LMT in the acidic media. The results of the EIS and Tafel tests determined the corrosion inhibition efficiency to be about 97% and 95%, respectively. The microscopy analysis showed that the surface suffered lower corrosion damages in the presence of LMT. Besides, the adsorption of LMT on the anodic sites of the surface through its sulfur atom was verified by EIS and XPS studies.