Mixtures of sunflower oil diethanolamide with sulfur-containing organic substances as inhibitors of sulfuric acid corrosion of Steel 3

• A.G. Berezhnaya and V.V. Chernyavina

Southern Federal University, ul. Zorge 7, 344090 Rostov-on-Don, Russia

Abstract: The protective effect of sunflower oil diethanolamide (DEAS), Kaptax, phenylthiourea (PTU), diphenylthiourea (DPTU) and sodium diethyldithiocarbamate (DEDTC), as well as mixtures of DEAS with sulfur-containing organic substances during the corrosion of steel 3 in a 0.5 M sulfuric acid solution was studied using gravimetry, polarization curve recording and impedance spectroscopy. It was found that at the highest studied concentration of DEAS, Kaptax, DPTU, PTU and DEDTC provide protection of steel from corrosion in sulfuric acid by 93.0; 99.9; 98.7; 98.7, and 96.3% at a temperature of 25℃, respectively. A mixture of DEAS (0.5%) with organic sulfur-containing substances (5·10^–5…10^–3 M) protects steel at the specified temperature by 85.0–99.6%. As temperature increases, the effectiveness of most individual compounds decreases. Increased inhibition with a temperature increase to 60℃ is observed for inhibitor mixtures with the highest concentrations of the sulfur-containing component. The influence of the components and their mixtures on specific electrode reactions of the corrosion process was determined. The degree of surface coverage by inhibitors and the free energy of adsorption were determined.

Keywords: inhibitor, low-carbon steel, sulfuric acid, amides

Int. J. Corros. Scale Inhib., 2026, 15, no. 1, 395-404
doi: 10.17675/2305-6894-2026-15-1-20

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