A comprehensive analysis of<i> Arum</i><i> dioscoridis</i> plant leaf extract as a corrosion inhibitor for mild steel in 1 M HCl: Synthesis, characterization, surface analysis observations, experimental and DFT studies

Background: Corrosion occurs wherever metal and its alloys exist. Protection of metals with corrosion inhibitor is a popular topic. Considering environmental concerns and human health, it is more favorable to use green corrosion inhibitors than traditional corrosion inhibitors. Methanol extract of Arum dioscoridis (AD) becomes a potential green corrosion inhibitor and it can be used in industrial areas. Methods: Corrosion efficiency, corrosion behavior and corrosion mechanism of Arum dioscoridis leaf extract on mild steel (MS) are illuminated in 1 M HCl by Tafel curves, electrochemical impedance spectroscopy (EIS), linear polarization resistance (LPR), zero charge potential, structural and surface morphological analysis and density functional theory (DFT). Significant findings: The extract function as mixed-type corrosion inhibitor with predominantly cathodic action. Inhibition efficiency was reached the value of 97 %. Polarization resistance is measured as 761 Omega cm2 at 1000 ppm of AD. The high inhibition efficiency was attributed to phytochemicals in the AD extract. A high activation energy (70.34 kJ/mol) for inhibited solution than that of in blank solution (49.66 kJ/mol). Both physisorption and chemisorption are responsible for formation of a protective layer on MS surface to inhibit the electrochemical reactions. Optimized molecular structures in phytochemicals confirmed the inhibitive properties via DFT.