ABSTRACT
Due to the environmental toxicity of chemical inorganic corrosion inhibitors (synthetic), green inhibitors are potential alternative. Herein, a comprehensive study of grape pomace extract and its active components (2-phenylacetaldehyde, Hexanal) as effective vapour phase corrosion inhibitor of mild steel is reported. Corrosion control was performed by potentiostatic polarization, electrochemical impedance spectroscopy and gravimetric measurements. SEM, AFM and FTIR techniques were also used to study the corrosion inhibition. Inhibition mechanism parameters are discussed. Quantum mechanics calculations have been applied within the framework of the density functional theory (DFT) to five major molecules of grape pomace extract. The electronic parameters that are calculated include: EHOMO, ELUMO, energy gap, electronegativity (χ), hardness (η), electrophilicity index (ω), electron charge transfer (∆N) and energy change (ΔE). Our results confirm the generally held assumption that there is a synergistic effect between the different organic molecules present in plant extracts towards enhancing the corrosion inhibition of these extracts on metals and alloys in varied aggressive media.
