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arXiv · 2102.02006

Inhibition of steel corrosion with imidazolium-based compounds -- experimental and theoretical study

Dominik Legut·Andrzej P. Kądzielawa·Petr Pánek·Kristýna Marková·Petra Váňová·Kateřina Konečná·Šárka Langová
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Abstract

This work aims to investigate the corrosion inhibition of the mild steel in the 1 M HCl solution by 1-octyl-3-methylimidazolium hydrogen sulphate 1-butyl-3-methylimidazolium hydrogen sulphate, and 1-octyl-3-methylimidazolium chloride, using electrochemical, weight loss, and surface analysis methods as well as the full quantum-mechanical treatment. Polarization measurements prove that studied compounds are mixed-type inhibitors with a predominantly anodic reaction. The inhibition efficiency obtained from the polarization curves is about 80-92% for all of the 1-octyl-3-methylimidazolium salts with a concentration higher than 0.005 mol/l, while it is much lower for 1-butyl-3-methylimidazolium hydrogen sulphate. The values measured in the weight loss experiments (after seven days) are to some extent higher (reaching up to 98% efficiency). Furthermore, we have shown that the influence of the alkyl chain length on the inhibition efficiency is much larger than that of the anion type. Furthermore, we obtain a realistic model of a single molecule on iron surface Fe(110) by applying the Density Functional Theory calculations. We use the state-of-the-art computational approach, including the meta-GGA strongly-constrained and appropriately normed semilocal density functional to model the electronic structure properties of both free and bounded-to-surface molecules of 1-butyl-, 1-hexyl-, and 1-octyl-3-methylimizadolium bromide, chloride, and hydrogen sulphate. From the calculations we extract, the HOMO/LUMO gap, hardness, electronegativity, and charge transfer of electrons from/to molecules-in-question. It supports the experimental findings and explains the influence of the alkyl chain length and the functional group on the inhibition process.

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Dominik Legut, Andrzej P. Kądzielawa, Petr Pánek, Kristýna Marková, Petra Váňová, Kateřina Konečná, Šárka Langová. 2021-07-30. Inhibition of steel corrosion with imidazolium-based compounds -- experimental and theoretical study. https://doi.org/10.1016/j.corsci.2021.109716

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