Imidazole−Fe Interaction in an Aqueous Chloride Medium: Effect of Cathodic Reduction of the Native Oxide

Abstract

The effect of the reduction of the native surface oxide of Fe on the binding of imidazole (as a corrosion inhibitor) with Fe in an aqueous brine solution has been addressed here. The surface interactions and corrosion inhibition efficiency were studied using X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS). It was shown that imidazole dissolved in brine bonds with the unreduced iron oxide surface via pyrrole-type nitrogen. However, surface interactions with Fe occur via both pyridine-type and pyrrole-type nitrogen atoms when imidazole is added to brine containing a cathodically reduced iron surface. The packing density of imidazole is found to be higher in the latter case with a corresponding increase in the corrosion inhibition efficiency.

Biologically inspired pteridine redox centres for rechargeable batteries

“…The peak in the N 1s spectra of the as-prepared electrode (full-width at half-maximum, FWHM: 2.23 eV) was broadened during the discharged state (FWHM: 2.57 eV) and then recovered after recharge (FWHM: 2.25 eV), which shifted the peak to lower energies and then back to the initial value. For the as-prepared electrode, the N 1s spectrum could be deconvoluted into two peaks with the same FWHM of 1.60 eV centred at 399.15 and 400.15 eV, which were assigned to conjugated (sp 2 ) -N ¼ and non-conjugated (sp 3 ) -NH-groups, respectively 31 . After discharge, an additional peak evolved at a lower binding energy, 398.40 eV, while the -N ¼ peak (399.15 eV) decreased, implying that reduction occurred at nitrogen atoms in the pyrazine ring.…”

Comparison of corrosion inhibitor performance based on green corrosion inhibitor of extract leaf tobacco and commercial imidazoline inhibitor in a sweet environment at carbon steel AISI 1045 in NaCl 3.5% solution

“…The presence of an amine functional group (N-H) present at the head of the imidazoline molecular structure, indicating the presence of an electron donor provided by the nitrogen atom in the pyrine to Fe of the test sample. Thus, a strong reaction exists between the imidazoline inhibitor and the test sample and a passive layer that protects the metal from corrosion [22]. The presence of a C-H bond as a branch chain indicates the presence of a hydrocarbon group on the metal surface.…”

“…The nitrogen atoms in pyridine will donate their electrons to Fe by chemisorption. While the electron pair on a nitrogen atom of Pyrrole, it is required for the stabilization of the aromatic chains of the head group of the imidazoline structure [22]. Then the non-polar hydrocarbon tail of this inhibitor molecule lies vertically to the metal surface.…”

“…The nitrogen atoms in pyridine will donate their electrons to Fe 2+ by chemisorption. While the electron pair on a nitrogen atom of Pyrrole is required for the stabilization of the aromatic chains at the head of the imidazoline structure and for forming complex compounds Fe 24 N 10 [22].…”

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

“…Current calculations are therefore more relevant for the reduced patches at the surface, where the oxide film has been breached. 17 Moreover, for obvious modelling reasons we also consider the adsorption at the metal/vacuum interface, although with respect to corrosion and its inhibition, the solid/water interface is far more appropriate. Current calculations are therefore to be taken only as a first crude attempt to address the inhibitor-surface bonding.…”