Experimental, DFT and MC simulation analysis of Vicia Sativa weed aerial extract as sustainable and eco-benign corrosion inhibitor for mild steel in acidic environment

Abstract

In the current investigation, the corrosion inhibition efficacy of a weed, Vicia Sativa has been investigated on the mild steel corrosion in 0.5 M HCl using weight-loss (WL) method, electrochemical impedance spectroscopy (EIS), potentiodynamic polarization measurements (PDP) and scanning electron microscope (SEM) techniques, in addition to surface examination analysis. This investigation revealed Vicia Sativa extract (VSE) as a green and eco-benign corrosion inhibitor for mild steel in 0.5 M HCl corrosive solution demonstrated an inhibition efficiency (IE%) of 91.24% at 298K in presence of 1000 ppm of VSE. The results attained from EIS investigations indicated an enhancement in polarization resistance (Rp) from 55.78 Ω at 50ppm to 191.05 Ω at 1000ppm, affirming the inhibitive potential of the investigated inhibitor. Additionally, on increasing the concentration of VSE from 50ppm to 1000ppm, the values of icorr and corrosion rate (CR) decreased from 554.05 μA to 122 μA and 6.438mmy−1 to 1.4176mmy−1, demonstrating the excellent inhibition potential of VSE on the mild steel corrosion. Additionally, the cathode Tafel slope (βc) (from −142.76 to −153.24mV/dec) and anode Tafel slope (βa) (from 127.79 to 134.71mV/dec) values rarely altered when the inhibitor was introduced with increasing concentration from 50ppm to 1000ppm, showing that the process of hydrogen evolution stayed intact, revealing the inhibitor molecule adhesion on the metallic substrate which lessened the degree of active spots available for the reaction while sustaining the charge transfer process of hydrogen generation. Furthermore, integrated computational investigations, such as density functional theory (DFT) and Monte Carlo (MC) simulations confirms the potent inhibitory efficacy of VSE.