The use of a Schiff base derivative to inhibit mild steel corrosion in 1 M HCl solution: a comparison of practical and theoretical findings

• H.S. Aljibori¹, A.H. Alwazir¹, S. Abdulhadi², W.K. Al-Azzawi³, A.A.H. Kadhum⁴, L.M. Shaker⁵, A.A. Al-Amiery^2,5 and H.Sh. Majdi⁶

¹ College of Engineering, University of Warith Al-Anbiyaa, Karbalaa, 56001, Iraq
² Energy and Renewable Technology Centre, University of Technology–Iraq, Baghdad, 10001, Iraq
³ Al-Farahidi University, Baghdad, 10001, Iraq
⁴ Al-Ameed University, Karbalaa, 56001, Iraq
⁵ Department of Chemical and Process Engineering, Faculty of Engineering and Build Environment, Universiti Kebangsaan Malaysia, Bangi, Selangor 43600, Malaysia
⁶ Department of Chemical Engineering and Petroleum Industries, Al-Mustaqbal University College, Babylon 51001, Iraq

Abstract: The corrosion-preventing capabilities of a new Schiff base namely, 6-(4-bromophenylimino)-guaiacol, were investigated using experimental and quantum chemical theoretical studies on mild steel in 1 M hydrochloric acid solution. The weight loss technique was used to investigate the anticorrosion performance of 6-(4-bromophenylimino)guaiacol as an inhibitor for mild steel coupons. The weight loss results showed that the tested inhibitor has a high level of inhibition efficiency. The inhibition efficiency was observed to rise as the inhibitor concentration was increased from 0.1 to 0.5 mM, according to the experimental findings. In the presence of 0.5 mM inhibitor, the maximal inhibition efficiency was 95.1%. Furthermore, the adsorption process was estimated and described using the Langmuir adsorption isotherm model. Scanning electron microscopy analysis confirmed the adsorption of 6-(4-bromophenylimino)guaiacol molecules on the mild steel surface and thereby shielding from corrosion. In addition, computer computations were carried out in order to establish a link between the electronic and structural properties of the tested inhibitor molecules. Chemical computation studies employing density function theory (DFT) were also conducted. The anticorrosion ability of the tested inhibitor is related to the computed chemical quantum parameters like highest occupied molecular orbital (E_HOMO) and lowest unoccupied molecular orbital (E_LUMO), energy gap (ΔE), global softness (σ), global hardness (η), electronegativity (χ), and fraction of electrons transferred (ΔN) and Mulliken charges on the atoms. These factors can be realized by the optimization of the investigated organic compound. The inhibitory mechanism was elicited based on experimental and theoretical findings. Theoretical and experimental findings are in agreement.

Keywords: Schiff base, mild steel, corrosion, HCl, weight loss, DFT

Int. J. Corros. Scale Inhib., 2022, 11, no. 4, 1435-1455
doi: 10.17675/2305-6894-2022-11-4-2

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