Alkyl pyridine ionic liquid as a green corrosion inhibitor for mild steel in acidic medium

Abstract

Using electrochemical measurements, the corrosion inhibition performance of pyridine bromide ionic liquid corrosion inhibitors on low carbon steel was evaluated under different concentrations and alkyl chain lengths of anions. The optimal process conditions were obtained: at 25 °C, in a 1 M HCl corrosion medium, the 1-dodecyl-3-methylpyridine bromide ionic liquid ([C₁₂Py]Br) exhibited the best corrosion inhibition effect, with maximum inhibition rates of 94.1%. The study mechanism showed that the adsorption process was a mixed adsorption dominated by chemical adsorption. Surface analysis (SEM/EDS, XPS) and quantum chemistry results verified that [C_nPy]Br could form a protective film on the surface of low carbon steel and inhibit its corrosion. In addition, molecular dynamics simulations were used to analyze the adsorption behavior of corrosion inhibitor molecules on the Fe(110) surface, and the formation sequence of bond and non-bond interactions in the Fe corrosion inhibitor molecular system on the Fe(110) surface was obtained, which was consistent with the experimentally determined corrosion inhibition efficiency. The radial distribution function (RDF) showed that the adsorption mode of the corrosion inhibitor on the metal surface was a mixed adsorption dominated by chemical adsorption and supplemented by physical adsorption.