Extensive electrochemical study and surface examinations combined with DFT theoretical approaches of Zoffa extracts as green corrosion inhibitors for ASTM/A36 steels in acidic solutions

Abstract

Sustainable Zoffa extract solution provides organic molecules with structures including heteroatoms, aromatic rings, and polar groups, which play an important role in the adsorption and inhibition process on metal substances in corrosive environments. The main components in Zoffa extract solution, such as phenylacetaldehyde, myrtenol, pinocamphone, and isopinocamphone, can easily be adsorbed on the ASTM/A36 steel surface and appropriately control its corrosion rate in 1 M HCl at different temperatures. The adsorption process was characterized using FTIR, UV/vis, fluorescence SEM, atomic force microscopy (AFM), and the contact-angle technique. The inhibition performance was evaluated using chemical methods, such as mass loss (ML) and hydrogen evolution (HE), and electrochemical methods, such as potentiodynamic Tafel polarization (PTP), electrochemical impedance spectroscopy (EIS), cyclic polarization sweep (CPS), and the Mott–Schottky technique (MST). The PTP explained the mixed inhibition effect of the Zoffa extract with predominantly cathodic inhibition. A Zoffa concentration of 1500 ppm provided an average inhibition protection of 94.68%. The Zoffa molecule was adsorbed on the electrode surface according to the Langmuir isotherm. Thermodynamic parameters involving E*, ΔH*, ΔS*, and ΔG* were calculated using Arrhenius and transition-state equations. The quantum parameter was theoretically estimated using the density-functional-theory method with 6-311++ G(d,p) as the basis function set to elucidate the correlation between the molecular structure of the inhibitor and its inhibition performance.

Keywords:

• Corrosion inhibitor
• SEM
• AFM
• contact angle
• Mott–Schottky
• DFT method

Disclosure statement

No potential conflict of interest was reported by the author(s).