ISSN 2305-6894

New quinoxaline derivative as a green corrosion inhibitor for mild steel in mild acidic medium: Electrochemical and theoretical studies

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1 Laboratory of Separation Procedures, Faculty of Sciences, Ibn Tofail University, Kenitra, Box 133, Kenitra, Morocco
2 Laboratory of Medicinal Chemistry, Faculty of Medicine and Pharmacy, Mohammed V University, Rabat, 10170 Rabat, Morocco
3 Laboratory of Physical Chemistry, Faculty of Sciences, Moulay Ismail University, Meknès, Morocco
4 Department of Chemistry, AN-Najah National University P.O. Box 7, Nablus, Palestine
5 Institut Supérieur des Professions Infirmières et Techniques de Santé, ISPITS-Fès, Hôpital Elghassani, Fes, Morocco
6 Laboratory of Materials, Nanotechnology and Environment, Faculty of Sciences, Mohammed V University, Av. Ibn Battouta, Box 1014 Agdal-Rabat, Morocco

Abstract: The influence of new quinoxaline derivative namely (E)-3-(4-methylstyryl)quinoxalin-2(1H)-one (QNMS) on the corrosion of mild steel in 1 M HCl was studied using using Tafel polarization and electrochemical impedance spectroscopy. Quantum chemical calculations were performed using methods based on density functional theory (DFT / B3LYP) and Monte Carlo simulations (MCs). The inhibitor studied [(E)-3-(4-methylstyryl)quinoxalin-2(1H)-one (QNMS)] showed a maximum inhibition efficiency of 91% at 10–3 M. Adsorption of QNMS on mild steel surface follows the Langmuir adsorption isotherm in order to discover the mode of adsorption process, various thermodynamic and activation parameters were evaluated. Potentiodynamic polarization studies show that QNMS compound acts as a mixed inhibitor. Data obtained from EIS measurements were analyzed to model the corrosion inhibition process through the appropriate equivalent circuit model. The EIS data bring that, the development of a protective layer of QNMS increases the charge transfer resistance and decreases the double layer capacitance of mild steel in acid medium. Quantum chemical calculations were employed to study the electronic properties of QNMS to ascertain the correlation between the inhibitory effect and the molecular structure. Both the experimental and theoretical (EHOMO, ELUMO, ΔE, µ, ΔN,... and Monte Carlo simulation) results are in good agreement with each other in this regard and confirm that QNMS is an effective inhibitor.

Keywords: mild steel, HCl, corrosion inhibition, quinoxaline, DFT, Monte Carlo simulations

Int. J. Corros. Scale Inhib., , 2, 241-256 PDF (869 K)
doi: 10.17675/2305-6894-2019-8-2-6

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