Nitrogen-containing five-membered heterocyclic compounds as corrosion inhibitors for metals in solutions of mineral acids – An overview

• Ya.G. Avdeev and Yu.I. Kuznetsov

A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Leninskii pr. 31, 119071 Moscow, Russian Federation

Abstract: The review describes the current state of studies in the field of protection of ferrous and nonferrous metals from corrosion in solutions of mineral and organic acids by N-containing five-membered heterocyclic compounds (NFHC). Literature data on the protection of various metals (steels, copper-, zinc-, and aluminum-based alloys) by these corrosion inhibitors (CIs) in acid solutions are generalized. The specifics of the mechanism of their protective effect are discussed. Analysis of data on the free adsorption energy of NFHC on the surface of various metals in acid media often allows assuming the chemisorption character of their interaction, which to a great extent explains the efficiency of these compounds in corrosion inhibition. The unique ability of composite NFHC-based CIs to protect metals in extremely corrosive media (high temperature acid solutions (t up to 200°C) and acid solutions containing Fe(III) salts) is discussed. The ability of such composite CIs to inhibit corrosion in such corrosive media is based on the ability of NFHCs to form polymolecular protective layers on the metal surface, with molecules in such layers being chemically bound with each other and with the metal surface. The chemical bonds between NFHC molecules in the protective layer result from the formation of a polymeric complex compound with the metal cations formed in the course of corrosion. It is shown that it is more expedient to use not individual NFHCs but NFHC-containing mixtures. The reference list includes 260 references.

Keywords: acid corrosion, corrosion inhibitors, metal, steel, nitrogen-containing heterocyclic compounds, pyrrole, pyrrolidine, pyrrolidone, pyrazole, pyrazoline, imidazole, imidazoline, imidazolidine, triazole, tetrazole, indole, benzimidazole, benzotriazole

Int. J. Corros. Scale Inhib., 2021, 10, no. 2, 480-540 PDF (1 342 K)
doi: 10.17675/2305-6894-2020-10-2-2

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