Protection of low-carbon steel in phosphoric acid solutions by mixtures of a substituted triazole with sulfur-containing compounds

Abstract

Based on IFKhAN-92 inhibitor, which is a substituted triazole, and sulfur-containing additives, efficient mixtures have been developed that protect low-carbon steel in phosphoric acid solutions in a broad range of acid concentrations (2.0-8.0 M) and temperatures (0-95C). . However, only some of them (triazoles and sulfur-containing compounds) provide a high protection degree, Z  90%. A promising method to prevent steel corrosion in phosphoric acid solutions involves mixed inhibitors. Various additives are used to enhance the effect of inhibitors: halide anions for quaternary ammonium salts and purine derivatives [13,14], cerium (IV) cations for sodium oleate [15], and uracil for a substituted tetrazole [16]. Addition of sulfur-containing compounds makes it possible to use the "PKU" industrial inhibitor in these media [17]. Based on IFKhAN-92, a triazole derivative, we have developed efficient inhibitor blends for the protection of low-carbon steels in mineral acid solutions [18,19]. It appeared expedient to develop a formulation for the protection of low-carbon steel in phosphoric acid solutions based on IFKhAN-92 inhibitor. Experimental procedureThe corrosion rate of St3 low-carbon steel in H 3 PO 4 solutions was determined from the mass loss of specimens (at least three specimens per experimental point) sized 50.0 mm  20.0 mm  1.5 mm, using 50 ml of the acid solution per specimen, in the temperature range

Protection of metals in phosphoric acid solutions by corrosion inhibitors. A review

“…For example, the corrosion rate (k) of St3 steel (content in mass percent, %: 0.14-0.22 С, 0.05-0.17 Si, 0.40-0.65 Mn, up to 0.30 Ni, up to 0.30 Cu, up to 0.30 Cr, up to 0.08 As, up to 0.05 P, up to 0.05 S, balance Fe) in 2 М H 3 PO 4 (0-95С) is from 2.4 to 520 g/(m 2 h). A growth in acid concentration (С) in the solution (60С) from 1 to 8 M accelerates corrosion from 29 to 190 g/(m 2 h) [11]. Similar trends in the behavior of low-carbon steels were found elsewhere [12][13][14][15].…”

“…In practical terms, the use of mixtures of triazole derivatives with S-containing compounds seems promising. Such formulations based on 3-substituted 1,2,4-triazole, the IFKhAN-92 CI, efficiently inhibit low carbon steel corrosion [11,124,125], although individual components of these mixtures do it poorly (Figure 1). Mixtures of this triazole with anionic sulphur-containing additives (KNCS, DDTC, Na 2 S) give the maximum reduction of corrosion: they provide at least 10 times smaller k values than KI-containing formulations.…”

Protection of nickel-chromium steel in sulfuric acid solution by a substituted triazole

“…We studied KI, KBr, and KCNS, which enhance the protective effect of triazoles in corrosion of low-carbon steel in mineral acid solutions [18,19], as additives to IFKhAN-92 inhibitor.…”

Organic corrosion inhibitors: where are we now? Part I. Adsorption

“…They have led to the development of a CI having high efficiency not only in solutions of various acids but also in media containing hydrogen sulfide [17][18][19][20][21][22][23][24]. The main component of this inhibitor is a triazole derivative (IFKhAN-92) characterized by the ability to protect steel and other metals at elevated temperatures up to 200C.…”