ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Influence of different anions on the corrosion-inhibition performance of pyridyl ionic liquids

Lei Fan, Yuan Gao, Qiang Bi, Long Shi, Changbin Tang, Chengxian Yin, and Juanqin Xue

State Key Laboratory for Performance and Structure Safety of Petroleum Tubular Goods and Equipment Materials, Xi’an, China

E-mail: biq@xauat.edu.cn

Received: 28 July 2023  Accepted: 1 October 2023

Abstract:

In this study, it was possible to investigate the effect of pyridine-type ionic liquids with the bromides Br⁻, BF₄⁻ and PF₆⁻ in N-butyl-4-methylpyridine (B4MePyBr), N-butyl-4-methylpyridinium tetrafluoroborate (B4MePyBF₄) and N-butyl-4-methylpyridinium hexafluorophosphate (B4MePyPF₆) as the anions on the reduction of corrosion on N80 steel in hydrochloric acid solution. A loss-in-weight test showed that the corrosion-inhibition efficiency increased with an increase of the corrosion inhibitor concentration, and the corrosion-inhibition efficiency reached 87.1% when B4MePyBF₄ was added at a concentration of 10.0 mmol·L⁻¹ at 25 °C. The corrosion-inhibition efficiency of the three followed B4MePyBF₄ > B4MePyBr > B4MePyPF₆. Surface morphology tests showed that the corrosion inhibitors were effectively adsorbed on the carbon steel surface and the adsorbed film layer was tight. Quantum calculations showed that the LUMO and HOMO orbital energy polarities of B4MePyBF₄ were the smallest, indicating that it most strongly adsorbed on the metal surface and had the best retardation effect, which was consistent with the actual experimental results.

Graphical abstract

The corrosion-inhibition behavior of B4MePyBF₄, B4MePyBr, and B4MePyPF₆ in hydrochloric acid on N80 steel was investigated. The corrosion-inhibition efficiency increased with corrosion inhibitor concentration. The corrosion-inhibition efficiency of the three followed the trend B4MePyBF₄ > B4MePyBr > B4MePyPF₆.

Keywords: Ionic liquids; Corrosion inhibitors; Hydrochloric acid; N80 steel; Orbital energy polarities

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-023-03131-5

Chemical Papers 78 (2) 927–936 (2024)