Self-assembled Films Glutamic Acid and Its Derivatives on 304 Stainless Steel

The corrosion inhibition performance of L-glutamic, L-Pyroglutamamide and L-Pyroglutamic self-assembled films for 304 stainless steel in 0.5 mol/L H2SO4 solution was investigated by electrochemical impedance spectroscopy, polarization curves, quantum chemical calculations and molecular dynamics. The results of electrochemical method showed that three kinds of inhibitors performed pretty inhibiting efficiency for 304 stainless steel in 0.5 mol/L H2SO4 solution. And at the same concentration of inhibitors, the longer the assembled time, the better the effect of inhibition. According to the results of polarization curves, all these inhibitors were cathodic inhibitors. The results of quantum chemical calculations were the same as those of electrochemical method, and the inhibition efficiency of the three inhibitors was related the values of EHOMO and ΔE. The inhibition performance of the compound was assumed to occur by adsorption on the 304 SS surface through the active centers in the molecule. The results indicated that the corrosion inhibition was due to the formation of a chemisorbed film on the steel surface. The inhibition efficiency of the three inhibitors decreased as follows: L-Pyroglutamic>L-Pyroglutamamide>L-glutamic.