A detailed investigation of the chloride-induced corrosion of mild steel in the presence of combined green organic molecules of Primrose flower and zinc cations

This study aims at finding a novel natural species for the corrosion mitigation of the mild steel immersed in saline solutions. For this purpose, for the very first time, the inhibition potent of different blends of the petal extract of Primrose flower (PPE) and zinc cations were studied. The PPE and PPE:Zn composite adsorption on the steel substrate was examined by Fourier-transform infrared spectroscopy (FT-IR). Surface characterizations of the metal surface were carried out using scanning electron microscopy (SEM), ultraviolet-visible spectroscopy (UV-Vis), grazing incidence X-ray diffraction (GIXRD), atomic force microscopy (AFM) method and contact angle measurement (CA). The inhibition actions of the PPE:Zn containing solutions were evaluated by means of the electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization spectroscopy (PPS). Surface studies proved the chelation between the organic molecules of the PPE and Fe2+/Zn2+ cations. In the presence of PPE and Zn alone, the inhibition efficiencies were in the range of 40-80%while the mixture of 300 ppm PPE + 700 ppm Zn has resulted in a 95.3% protection degree. It was found that the protection mechanism was mixed-type with anodic reaction retardation dominancy. In addition, computational methods (density functional theory, DFT and molecular dynamics, MD and Monte Carlo, MC) were utilized to study the reactivity and interfacial adsorption of extract molecules. These computations ensured the adsorption of green molecules over the substrate of the target. (C) 2019 Published by Elsevier B.V.