Experimental and theoretical evaluation of (iso)quinolinium bromide derivatives as corrosion inhibitors of steel E24 in 0.5 M H2SO4 solution

• M.E. Said^1,2, H. Allal^1,3, B. Mezhoud^1,4, M. Bouchouit¹, A. Chibani¹ and A. Bouraiou¹

¹ Unité de Recherche de CHimie de l′Environnement, et Moléculaire Structurale, CHEMS, Université des Frères Mentouri, Constantine, Algeria
² Faculté de Technologie-BP 166 Université Mohamed Boudief M’sila 28000, Algeria
³ Département Génie des Procédés, Faculté Génie des Procédés, Université Salah Boubnider Constantine 3, Constantine, Algeria
⁴ Faculté des sciences Exactes et Informatique, Université Mouhamed Seddik Benyahial de Jijel BP 98 Ouled Aissa, Jijel 18000, Algeria

Abstract: The ability of (2-methoxy-2-oxoethyl)quinolinium bromide (Qui⁺, Br^–) and (2-methoxy-2-oxoethyl) iso quinolinium bromide (isoQui⁺, Br^–) were investigated for corrosion inhibition of mild steel E24 in H₂SO₄ by impedance spectroscopy and potentiodynamic polarization measurements. A series of experiments with various inhibitor concentrations were conducted. The results show that the corrosion rate decreases, inhibition efficiencies increase, and surface coverage increase with increasing inhibitor concentration. Potentiostatic polarization revealed that both inhibitors affected cathodic and anodic reactions, making them inhibitors of a mixed type with a significant cathodic inhibitory character. Several adsorption isotherms, including Langmuir, Temkin, and Frumkin, were investigated to understand the inhibitor’s adsorption behaviour. The adsorption of both compounds on a mild steel surface obeys Langmuir’s adsorption isotherm. In addition, the values of ΔG⁰_ads showed a physisorption effect for the two prepared inhibitors. To compare the chemical reactivity of Qui⁺, Br^– and isoQui⁺, Br^– and study the interactions between inhibitor molecules and the steel surface, different quantum chemical descriptors have been calculated, such as E_HOMO, E_LUMO, ΔE, χ, η, σ and ΔN. The results obtained reveal that the Qui⁺, Br^– has higher electronegativity (χ), global softness (σ), and global electrophilicity (ω) than the isoQui⁺, Br^– compound. The order of IE determined from experimental measurements is successfully supported by theoretical analysis.

Keywords: corrosion inhibitors, steel corrosion, quinolinium salt, electrochemical measurements

Int. J. Corros. Scale Inhib., 2023, 12, no. 2, 679-695
doi: 10.17675/2305-6894-2023-12-2-16

Download PDF (Total downloads: 100)

Back to this issue content: 2023, Vol. 12, Issue 2 (pp. 366-810)