Inhibitive Properties and Surface Morphology of a Group of Heterocyclic Diazoles as Inhibitors for Acidic Iron Corrosion

Abstract

The heterocyclic diazoles 3-amino-1H-isoindole, indazole, imidazole, 4-bromoimidazole, 4-methylimidazole, pyrazole, 4-nitropyrazole, and 4-sulfopyrazole were investigated as corrosion inhibitors of iron in 1 M HCl using ac and dc techniques. The polarization curves showed a decrease in corrosion current for the inhibitor-containing solution. Impedance spectra demonstrate that the charge-transfer resistance in the presence of these inhibitors was greater than in inhibitor-free solution, except for 4-nitropyrazole. The resistance increased with inhibitor concentration and with immersion time. The structural and electronic parameters of these diazoles were calculated using computational methodologies. The elemental composition and the speciation of the treated surfaces were investigated via XPS measurements, and morphological changes were monitored by vertical scanning interferometery.

Structural and mechanical properties of radiofrequency N2/H2cold plasma-nitrided C38 carbon steel

“…[27]. Finally, the small peak may be assigned to the oxygen atom of adsorbed water with characteristic binding energy of 533.1 ± 0.2 eV [28].…”

Evaluation of alkaloids extract of Retama monosperma (L.) Boiss. stems as a green corrosion inhibitor for carbon steel in pickling acidic medium by means of gravimetric, AC impedance and surface studies

“…The first two peaks correspond to the binding energy of the O 2-and OH -ions [45], in agreement with the presence of the iron oxide/hydroxide layer as detected in the Fe 2p 3/2 spectrum. The third peak at 532.7 eV may be assigned to oxygen of adsorbed water [46]. However, it is not possible to separate contributions of organic oxygen (O in carbonyl) since O 1s signal [47].…”

Effect of Mercapto and Methyl Groups on the Efficiency of Imidazole and Benzimidazole-based Inhibitors of Iron Corrosion

“…The Xray photoelectron spectra of iron and its oxides is well known. 6,31 Due to unpaired electrons in the valence band, iron compounds show a complex structure related to the multiplet splitting. 32 The center of main Fe 2p 3/2 peak in metallic iron is located at binding energy, E b , 706.8 eV, whereas the second peak of lower intensity is located at 711.4 eV.…”

“…Heterocyclic diazoles were also shown to be good inhibitors for iron in 1 M HCl. 6 Three types of iron species were identified on the inhibited surface: FeOOH, Fe 2 O 3 and Fe 3 O 4 . It was suggested that good inhibition agent should form an insoluble complex or surface species with low hydroxide content.…”

“…In slightly acidic solution more studies have been performed than in neutral chloride solution. [5][6][7][8][9] Combined electrochemical and computational HOMO/LUMO type study was performed for different imidazole-based inhibitors on iron in 1 M HCl. 5 The inhibition efficiency increased with increasing electron donating ability being the highest for amino-containing inhibitors.…”