Inhibitory protection of metals in acid solutions by hexamethylenetetramine. A review

• Ya.G. Avdeev

Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31-4, Leninsky prospect, 119071 Moscow, Russia

Abstract: Literature data on the protection of metals in acid solutions by adding hexamethylenetetramine (HMT) alone, products of its chemical modification, and mixed corrosion inhibitors containing HMT, have been summarized and analyzed. The physicochemical properties of HMT, information on the protection of various metals in acid media by HMT, and certain aspects of its inhibition mechanism are discussed. The effect of industrial inhibitors obtained by chemical modification of HMT (PB-5, PB-8/2, BA-6, PKU, PKU-M, PKU-3, PKU-E) and those containing HMT as a component of inhibitor mixtures (UM-1, UM-2, I-A-1, KI-1), on metal corrosion in various acid media is discussed. It is noted that the use of HMT in individual form for metal protection is not a promising approach. In contrast, the use of products of chemical modification of HMT or its addition to mixed corrosion inhibitors (CIs) allows one to achieve interesting results in the protection of metals in acid solutions. HMT is a convenient and cheap platform for making CIs by chemical modification. As a reactive compound, HMT easily enters into chemical reactions with various substances to form products consisting of mixtures of nitrogen-containing organic compounds with diverse structures. Such mixtures efficiently inhibit the corrosion of metals in acid media. When developing mixed corrosion inhibitors containing HMT, special attention should be paid to three-component mixtures. Such compositions allow one to achieve effective protection of steels in extremely corrosive media (high-temperature acid solutions and solutions containing Fe(III) salts). The bibliography includes 141 references.

Keywords: metals, acid corrosion, corrosion inhibitors, hexamethylenetetramine, urotropine, hexamine, urasal, methenamine

Int. J. Corros. Scale Inhib., 2025, 14, no. 3, 1241-1267
doi: 10.17675/2305-6894-2025-14-3-13

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