ISSN 2305-6894

Synthesis of oleic-imidazoline and investigation on its inhibition efficiency for the corrosion of low carbon steel in chloride environments

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1 Department of Chemistry, Faculty of Mathematics and Natural Sciences (FMIPA), Universitas Indonesia, Depok 16424, Indonesia
2 Department of Chemical Engineering, Faculty of Engineering, Universitas Indonesia, Depok 16424, Indonesia
3 Department of Chemistry, Faculty of Mathematics and Natural Sciences (FMIPA), Universitas Sumatera Utara, Medan 20155, Indonesia
4 PT Pertamina Research and Technology Center, Jl. Raya Bekasi Km.20, Pulogadung, Jakarta 13920, Indonesia

Abstract: Carbon steel is the principal material used in oil and gas production pipelines. However, carbon steel is vulnerable to corrosion by corrosive media it contacts, and this causes economic losses. The corrosion rate of carbon steel is inhibited by imidazoline, an organic corrosion inhibitor. In this study, oleic-imidazoline was successfully synthesized from triethylenetetramine and oleic acid under reflux at 100–140°C for 12 h. The synthesized compound was characterized for its structure by using FTIR, UV-Vis, NMR (1H and 13C), and LC-MS/MS spectral data. Oleic-imidazoline showed a maximum absorption peak at a wavelength of 203.8 nm (UV-Vis), absorption peaks at 1656.51 cm–1 belonging to C=N bond (FTIR), a peak at a chemical shift of 2.17 and 3.30–3.48 ppm indicating H–C–C=N and imidazoline ring proton, respectively (1H NMR), and a peak at the chemical shift of 164.6 ppm fitting C=N (13C NMR). LC-MS/MS showed that oleic-imidazoline was a major component in the synthesized compound with [M+H]+ 393.37 m/z at rt 10.87 min. The oleic-imidazoline’s performance as a corrosion inhibitor toward low carbon steel in a 1% NaCl solution was measured using two methods, which are Tafel polarization and weight loss. The highest inhibition efficiency percentage (%IE) resulted from the two methods are 83.26% and 83.33%, respectively. Oleic-imidazoline reveals good performance to inhibit the corrosion since this compound undergoes physisorption with slight chemisorption on low carbon steel in chloride environment.

Keywords: chloride environment, corrosion inhibitor, low carbon steel, oleic-imidazoline

Int. J. Corros. Scale Inhib., , 10, no. 3, 1282-1293
doi: 10.17675/2305-6894-2021-10-3-25

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