The corrosion inhibition performance of the food dye Green S (GS) on 304L austenitic stainless steel in 0. 5 M H2SO4 was evaluated through electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), scanning electron microscopy (SEM), and theoretical calculations using density functional theory (DFT) and Monte Carlo (MC) simulations. The results showed that GS acts as a good anodic corrosion inhibitor and exhibits an inhibition efficiency of 91. 2%, obtained at the concentration 400 ppm of inhibitor. The study of the adsorption isotherm indicates that GS molecules adhere to the stainless steel surface according to Temkin adsorption isotherm, with a standard free energy ({G^{₀₃ₒ}}) of ‒19. 08 kJ mol–1, suggesting spontaneous physical adsorption. SEM surface morphology analysis confirmed the formation of a uniform protective layer in the presence of GS, along with a reduction in surface degradation compared to uninhibited surface. Theoretical study highlighted a strong correlation between the electronic properties of GS and its inhibition behavior, as predicted by frontier molecular orbital analysis and adsorption energy calculation, which were consistent with the experimental data. This study demonstrates that GS is an efficient and low-cost corrosion inhibitor, offering significant potential for protection of stainless steel in acidic environments.
Ouchenane et al. (2026) studied this question.