DOI: https://doi.org/10.55373/mjchem.v28i1.422

Keywords: Adsorption, H2SO4, metal surface, synthesis, weight loss

Abstract

In this study, the inhibitory performances of three pyridinium bromide derivatives, namely 1-benzyl-4-((3-(4-chlorobenzylidene)-2-oxocyclohexylidene)methyl)pyridin-1-ium bromide, C1; 4-((3-(4-chlorobenzylidene)-2-oxocyclohexylidene)methyl)-1-(2-oxopropyl)pyridin-1-ium bromide, C2; 4-((3-(4-chlorobenzylidene)-2-oxocyclohexylidene)methyl)-1-(2-oxo-2-phenylethyl)pyridin-1-ium bromide, C3, were investigated for mild steel corrosion in 1 M H₂SO₄ for 24 hours at 25˚C. The evaluation was conducted using the weight loss technique, while the molecular structures were confirmed by Proton Nuclear Magnetic Resonance (¹H-NMR) and Fourier Transform Infrared (FT-IR) Spectroscopy. The results showed that the inhibition efficiency (IE%) of all three compounds was strong and improved gradually as the inhibitor concentration increased. This improvement was attributable to increased adsorption of inhibitor molecules on the mild steel surface, resulting in higher surface coverage(θ). At the same time, the rate of corrosion decreased. Furthermore, the adsorption of the studied compounds on the surface of mild steel followed the Langmuir isotherm model, with high Kads values, which supported the substance's better inhibitive activity. The results indicated negative ΔG ads values, signifying that the adsorption of inhibitor molecules on the mild steel surface occurred spontaneously via a combined mechanism of physisorption and chemisorption. These results indicate that pyridinium bromide derivatives can act as promising and effective corrosion inhibitors for mild steel in acidic media.