Green corrosion inhibitors for mild steel in HCl medium: a comprehensive review on plant-based alternatives

The purpose of the article is to create an awareness of the utilizing organic inhibitors (plant inhibitors) to resist rust of mild steel (MS), which helps to reduce corrosion in HCl acidic medium. So, the motive of throughout this work is to replace the toxic artificial corrosion preventer with a non-toxic organic inhibitor. There are various kinds of plants that help resist the corrosion of steel. Weight-loss measurements, electrochemical impendence (EIS), X-ray diffraction (XRD), Fourier transform infrared (FT-IR), ultraviolet spectroscopy, atomic force microscopy (AFM), scanning electron microscopy (SEM), and theoretical calculations are some of the tests that help to characterize the green corrosion inhibitor. Presence of corrosion-resisting compounds identified through the surface roughness of metal in morphological studies of SEM, AFM. The spectroscopical studies of FT-IR helpful to identify the aromatic functional groups of layer formation. The heteroatoms present in the plant extract are combined with a lone pair of electrons by the adsorption mechanism like chemisorption and physisorption. Langmuir adsorption isotherm helps to study the adsorption capacity of the surface of the metal to the plant extract. The corrosion of MS is reduced when the inhibitor’s concentration rises. This review article summarizes different kinds of organic corrosion preventer and their inhibition efficiency (IE%) based on various concentration. The preparation of the corrosion inhibitor in different solvents like ethanol, methanol, acetone, ethyl acetate, distilled water. The testing techniques of surface studies, corrosion studies, Electro chemical studies, spectroscopic studies are explained well in this review paper.