Abstract
Hydrazone [N,N′-bis[2-hydroxynaphthylidene]amino]oxamide] derived from the condensation of ethanedihydrazide with 2-hydroxynaphthalene-1-carbaldehyde was synthesized and assessed on the basis of elemental analysis (CHN) and spectral (IR, mass, 13C/1H NMR and UV-Vis) measurements. The influence of N,N-bis([2-hydroxynaphthylidene]amino)oxamide (HAO) in terms of the inhibition of iron corrosion in concentrated sodium chloride solution (3.5 wt.% NaCl) after various exposure periods was assessed. Numerous electrochemical and spectroscopic assessment techniques were performed. Cyclic potentiodynamic polarization experiments indicated that the presence of HAO and its increased concentration decreased the corrosion of iron in NaCl solution by decreasing the corrosion values, anodic and cathodic currents, and corrosion rate. The electrochemical impedance spectroscopy results showed that HAO molecules greatly increased the corrosion resistance. The chronoamperometric experiments performed at −475 mV (Ag/AgCl) revealed that the HAO molecules decreased the absolute currents and reduced the probability of the occurrence of pitting corrosion. The effect of HAO on the inhibition of iron corrosion was also confirmed through scanning electron microscopy micrographs and energy-dispersive X-ray profile analyses, which proved that the surface of the iron sample exposed to chloride solution alone was pitted, while the presence of HAO molecules reduced the severity of the pitting corrosion. The results confirmed that the presence of HAO molecules inhibits the corrosion of iron and this impact increased when the exposure time was increased to 48 h.
Highlights
N,N -bis[2-hydroxynaphthylidene]amino]oxamide is an example of polyfunctional hydrazones, which are organic compounds that have fascinating biological properties, such as anti-inflammatory, analgesic, anticonvulsant, antitumor, and anti-HIV properties [1]
In view of the inhibitive impacts of organic compounds containing N and O heteroatoms, we were motivated to investigate the influence of small concentrations of a synthesized aromatic hydrazone named N,N -bis[2-hydroxynaphthylidene]amino]oxamide (HAO) on the corrosion of pure iron in freely aerated 3.5% NaCl solutions after exposure periods of 1 and 48 h
The N,N -bis[2-hydroxynaphthylidene]amino]oxamide inhibitor was isolated in a pure form
Summary
N,N -bis[2-hydroxynaphthylidene]amino]oxamide is an example of polyfunctional hydrazones, which are organic compounds that have fascinating biological properties, such as anti-inflammatory, analgesic, anticonvulsant, antitumor, and anti-HIV properties [1]. N,N -bis[2-hydroxynaphthylidene]amino]oxamide, which is regarded as one of the hydrazone compounds, was employed as a corrosion inhibitor towards the aluminum, copper, and carbon-steel in 1M HCl solutions using traditional weight loss measurements [25,26,27]. The organic compounds containing heteroatoms such as nitrogen, oxygen, phosphor, and sulfur, as well as multiple bonds in their molecular structures, are mostly proficient inhibitors of metallic corrosion (M = copper, iron, aluminum, etc.) in NaCl brine and other media through eliminating the undesirable destructive influence of the corrosive media towards the metal surface [28,29,30,31,32]. In view of the inhibitive impacts of organic compounds containing N and O heteroatoms, we were motivated to investigate the influence of small concentrations of a synthesized aromatic hydrazone named N,N -bis[2-hydroxynaphthylidene]amino]oxamide (HAO) on the corrosion of pure iron in freely aerated 3.5% NaCl solutions after exposure periods of 1 and 48 h. EIS plots were obtained from the open-circuit potential values at a frequency scan range of 100,000 to 0.1 Hz with ±5 mV amplitude sinusoidal wave perturbation
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