A comprehensive electronic-scale DFT modeling, atomic-level MC/MD simulation, and electrochemical/surface exploration of active nature-inspired phytochemicals based on Heracleum persicum seeds phytoextract for effective retardation of the acidic-induced corrosion of mild steel

Abstract

Strong acidic solutions are commonly utilized in various industrial processes, i.e., acid pickling and descaling, providing detrimental chemical and/or electrochemical corrosion, leading to the huge cost of waste as a result of materials destruction. Nowadays, plant-based corrosion inhibitors have become popular in industries due to their cost-effectiveness and eco-friendliness. In the present paper, the corrosion inhibition function of Heracleum persicum seeds extracts (HPSE) for 1 M HCl-induced mild steel (MS) corrosion has been performed experimentally (electrochemical and surficial studies) and theoretically (computer simulation). The HPSE chemistry was explored by Fourier transform infrared (FT-IR) spectroscopy and UV–Vis technique. The electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) analysis results illustrated 95% and 94% inhibition efficiency degrees during 5 h MS subjection to 1 M HCl + 400 ppm HPSE solution, respectively. Furthermore, the weight loss measurements were conducted in the range of 25–55 °C, illustrating 96% inhibition efficiency after 5 h immersion at 25 °C in the acidic solution. Additionally, the Tafel plots proved mixed (anodic/cathodic) HPSE corrosion inhibition activity in the acidic solution. Through the field emission scanning electron microscope (FE-SEM) (micro-scale) and atomic force microscope (AFM) (atomic-scale) methods, the smoother and more clean surface, indicating proper protection performance of HPSE, was achieved. Also, the CA experiment confirmed the metal surface hydrophobicity enhancement in the presence of HPSE (about 69°), which indicates the adsorption of the organic molecules such as pimpinellin and bergapten, at the MS/solution interface. The Raman spectroscopy of the metal substrate ascertained the MS surface covered by an almost smooth graphite-like inhibitive layer. The Langmuir isotherm proved the highest compliance with experimental data, representing the generation of protective mono-layer of inhibitors on the MS substrate. The theoretical findings suggested by electronic/atomic computer simulations supported the inhibitive chemicals interfacial adsorption through reactive centers.