Protection of steel in solutions of sulfuric and phosphoric acid by inhibitors based on pharmaceuticals

• Ya.G. Avdeev¹, K.L. Anfilov², Yu.I. Kuznetsov¹, V.A. Guzeeva², M.E. Ivanova² and A.S. Leont’yeva²

¹ A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Leninsky pr. 31, 119071 Moscow, Russian Federation
² Federal State Budgetary Educational Institution of Higher Education “Bauman Moscow State Technical University” (Kaluga Branch), Bazhenov str. 2, 248000 Kaluga, Russian Federation

Abstract: The effect of two veterinary drugs (tricillin and oxytetracycline) on the corrosion of St3 steel in solutions of sulfuric and phosphoric acids (20–95°C) has been studied by long-term corrosion tests (up to 7 days). It has been found that these drugs taken separately fail to provide significant protection of steel in the environments studied. Their use as two-component mixtures with NH₄NCS is more promising. A composite inhibitor of 0.1–0.2% oxytetracycline +0.01% NH₄NCS has been suggested. It can provide efficient long-term protection of steel in H₂SO₄ solutions in a wide range of acid concentrations (0.25–2.00 M) and temperatures t=20–80°С. This mixture significantly slows down the corrosion of low-carbon steel in 1.00 M H₃PO₄ at temperatures up to 95°C, limiting its corrosion rate to 10 g/(m²·h). The suggested formulation is not inferior in terms of steel corrosion inhibition efficiency in H₂SO₄ and H₃PO₄ solutions to a similar mixed inhibitor developed on the basis of сocamidopropyl betaine, an industrial surfactant.

Keywords: corrosion, corrosion inhibitors, pharmaceuticals, low carbon steel, sulfuric acid, phosphoric acid, oxytetracycline

Int. J. Corros. Scale Inhib., 2024, 13, no. 3, 1541-1552
doi: 10.17675/2305-6894-2024-13-3-10

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