Inhibition Performance of Amino Acids for Steel in Sulfuric Acid Solution

The inhibition effect of cystine and methionine on the corrosion of X65 steel in sulfuric acid solution (0.5 mol/L) was investigated using open-circuit potential measurements,polarization techniques and electrochemical impedance spectroscopy (EIS).The study revealed that the inhibitors had promising corrosion inhibition efficiency at low concentration and the inhibition efficiency (IE,%) increased with increasing the inhibitor′s concentration.At the same concentration,cystine was more efficient than methionine.The corrosion inhibition effect was based on the adsorption of the amino acid molecules and/or the deposition of corrosion products on the metal surface.Polarization curves revealed that the inhibitors were mixed type inhibitors.