Synthesis and Corrosion Inhibition Performance of Cysteine Derivatives

Three kinds of cysteine derivatives were synthesized and their structures were identified by infrared spectroscopy. The inhibition efficiencies of the three inhibitors were studied by weight-loss method and electrochemical impedance spectroscopy (EIS) .The results of weight-loss show that the inhibition rate was S-benzyl-cysteine > S-hexyl-cysteine > S-butyl-cysteine. The inhibition efficiencies of the first two were above 98% at 800 mg/L. The results of polarization curves indicated that S-benzyl-cysteine and S-butyl-cysteine functioned as mixed-type inhibitor. S-hexyl-cysteine was cathodic inhibitor at low concentration and mixed-type inhibitor at high concentration. The results of EIS show that the charge transfer resistance of metal surface increased with the inhibitor concentration increasing.