Experimental and computational study of L-Glutathione reduced as a green corrosion inhibitor for mild steel in alkaline environment

Abstract

L-Glutathione reduced (GSH) is a small molecule peptide found in large quantities in living organisms, particularly in animal liver cells. Its unique structure gives it great potential to act as an environmentally friendly and efficient corrosion inhibitor. The inhibition properties of GSH for mild steel in simulated concrete pore solutions (SCPS) containing chlorine was investigated by electrochemical tests and SEM-EDS surface analysis. According to the experimental results, GSH mainly blocked the cathodic corrosion reaction and has a corrosion inhibition efficiency of up to 92.3% at room temperature, enhancing the corrosion resistance of mild steel. The isothermal adsorption results indicate that the adsorption behavior of GSH on the surface follows the Langmuir isothermal adsorption model. Both quantum chemical calculations (QC) and molecular dynamics simulations (MD) show that GSH can be effectively adsorbed onto mild steel substrates, thus protecting the surface from erosion. Finally, the results of the above experiments and theoretical calculations are combined to elucidate the inhibitive mechanism: GSH molecules binds to the iron surface via the sulfur, nitrogen and oxygen atoms in the molecule, thus adsorbing to the iron surface in a tiled manner and forming a protective film to prevent the corrosive material from contacting the iron surface.