Detailed macro-/micro-scale exploration of the excellent active corrosion inhibition of a novel environmentally friendly green inhibitor for carbon steel in acidic environments

An environmentally friendly green inhibitor based on Clove seed aqueous extract was applied for corrosion mitigation of mild steel (MS) surface in 1 M HCl solution. Applying integrated experimental (electrochemical combined with surface morphological) and theoretical (molecular simulation connected with density functional theory) techniques the Clove seed aqueous extract inhibition properties were examined. Through EIS and polarization methods the electrochemical characteristics were probed. Using scanning electron microscopy (SEM), atomic force microscopy (AFM) and contact angle test the surface morphology of the un-inhibited and inhibited metal specimens was characterized. EIS analysis disclosed notable corrosion inhibition degree (93%) using 800 ppm Clove seed extract after 2.5 h metal immersion, which was ascribed to the inhibitor adsorption on the MS surface as evidenced by SEM micrographs. According to the polarization test results, the corrosion suppression occurred via retardation of combined cathodic and anodic reactions with small cathodic prevalence. The AFM photographs depicted that introducing 800 ppm Clove seed extract into corrosive media gave rise to more smooth steel surface. By following Langmuir adsorption isotherm the Clove seed extract molecules reacted with steel surface, resulting in steel coverage by a monolayer. To complement the experiments, detailed theoretical explorations at microscopic electronic and atomic levels were accomplished employing Monte Carlo (MC) in conjunction with molecular dynamics (MD) and electronic-structure density functional theory (DFT) to fundamentally examine the adsorption possibility and the reactive atomic regions of organic compounds of Clove seed extract playing crucial roles in metallic inhibition manner. (C) 2019 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.