Electrochemical and theoretical assessment of two heterocyclic Schiff bases as effective corrosion inhibitors for carbon steel in sulfuric acid solution

Abstract

This article aimed to synthesize and study the efficacy of two tryptophan Schiff base derivatives as corrosion inhibitors for carbon steel in 0.5 M H2SO4: (Z)− 3-(1 H-indol-3-yl)− 2-((4-nitro benzylidene)amino)propanoic acid (INB) and (Z)− 3-(1 H-indol-3-yl)− 2-((4-methoxybenzylidene)amino)propanoic acid (IMB). Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) were used in this investigation. The findings demonstrate that INB and IMB exhibit strong anticorrosive activity against the 0.5 M H2SO4 medium; the inhibition efficiency for 10−3 M of IMB inhibitor was 92%. The Langmuir adsorption isotherm demonstrates that both INB and IMB have strong adsorption on the metal substrate, with free energy ΔGads of − 36.8 kJ mol−1 and − 38.5 kJ mol−1, respectively. Using simulations based on density functional theory (DFT) and molecular dynamics simulation (MDS), the molecular structure of INB and IMB and their influence on the inhibition mechanism was discussed. By using DFT/MDS computational research, a strong correlation between the theoretical and experimental results was found.