Mixtures of berberine and dihydroberberine with sulfur-containing compounds as steel corrosion inhibitors in sulfuric acid

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

Southern Federal University, Bolshaya Sadovaya street 105/46, 344046 Rostov-on-Don, Russian Federation

Abstract: The inhibiting effect of berberine, dihydroberberine, phenylthiourea, diphenylthiourea, 2-mercaptobenzothiazole, and sodium diethyldithiocarbamate on the corrosion of low-carbon steel in sulfuric acid has been studied. It has been shown that in the concentration range of 10^–5–10^–4 mol/L at 25°C, these organic compounds decrease the corrosion rate of steel. Depending on the concentration, the protective efficiency of the compounds ranges within 34–94%. The efficiency decreases with an increase in temperature. The inhibitory effect of some compounds changes to corrosion stimulation at temperatures above 60°C. The compounds studied inhibitor the cathodic evolution of hydrogen, owing to which they reduce the corrosion rate of steel. It has been shown that mixtures of berberine and dihydroberberine with sulfur-containing organic compounds are more efficient as steel corrosion inhibitors. The protective effect of the mixtures on steel corrosion is 85–99.7% at 25°C. It has been found that in the majority of mixtures, the components strengthen the protective effects of each other. It has been shown that in the presence of mixtures in sulfuric acid, the effective activation energy of the corrosion process increases significantly and the capacitance of the double electrical layer decreases. Inhibitor mixtures inhibit both electrode reactions.

Keywords: acid corrosion, inhibitor mixtures, berberine, dihydroberberine, phenylthiourea, diphenylthiourea, Kaptax, sodium diethyldithiocarbamate, sulfuric acid

Int. J. Corros. Scale Inhib., 2022, 11, no. 3, 941-955
doi: 10.17675/2305-6894-2022-11-3-3

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