Some imidazolines and their mixtures with inorganic anions as inhibitors of acid corrosion of steel

• A.G. Berezhnaya¹, E.S. Khudoleeva² and V.V. Chernyavina¹

¹ Southern Federal University, st. Bolshaya Sadovaya 105/46, 344046, Rostov-on-Don, Russian Federation
² NPO NIIPAV, 62 Khimikov st., 347366, Volgodonsk, Rostov region, Russian Federation

Abstract: The effect of aminoethyloleylimidazoline (I), hydroxyethyloleylimidazole (II), diethylene-diaminoleylimidazoline (III), potassium chloride, rhodanide, and iodide, as well as their mixtures on the corrosion of low-carbon steel in 15% sulfuric acid was studied by gravimetric method, by recording polarization curves, and by electrochemical impedance spectroscopy. It was shown that the investigated imidazolines at a concentration of 0.5 wt% protect steel by 74–96% in the temperature range of 20–80°С. The degree of protection by inorganic anions in the concentration range of 10^–4–10^–2 mol/L varies from 67 to 99% at 20°C, depending on their nature. It was found that mixtures of imidazolines with the inorganic anions are more effective inhibitors of steel corrosion in sulfuric acid. They provide 95–99% protection of steel at 80°C. The additives studied and their mixtures are mixed-type inhibitors. The inhibitory effect of the additives is due to a change in the structure of the electric double layer, the effective activation energy for corrosion, and blocking of a part of the steel surface.

Keywords: corrosion, low-carbon steel, sulfuric acid, inhibitor, imidazolines, potassium halides, potassium thiocyanate

Int. J. Corros. Scale Inhib., 2021, 10, no. 2, 649-661 PDF (717 K)
doi: 10.17675/2305-6894-2021-10-2-11

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