ISSN 2305-6894

2018, Vol. 7, Issue 4 (pp. 460-…)

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Nitrogen-containing six-membered heterocyclic compounds as corrosion inhibitors for metals in solutions of mineral acids – A review

  • Ya.G. Avdeev
A. N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Leninskii pr. 31, Moscow, 119071 Russian Federation

Abstract: The current state of studies on metal protection from corrosion in mineral acid solutions by six-membered N-containing heterocyclic compounds is reviewed. Literature data on the protection of various metals in acid solutions by these compounds are summarized. The specific features of their protective action mechanism are discussed. The feasibility of metal protection by formulations containing these compounds, even in high-temperature corrosion, is noted. N-Containing six-membered heterocyclic compounds are prone to adsorption on metal surfaces from mineral acid solutions. Based on the free adsorption energy values of these corrosion inhibitors (CIs) on metal surfaces, it can be deemed with high probability that they are mostly bound to a metal by physical forces, but upon adsorption on its surface they slow down the cathodic and anodic reactions, and eventually inhibit its corrosion. Compounds containing S atoms or bulky substituents are most interesting. These compounds are adsorbed on metals more strongly and behave as more efficient CIs. It often happens that such CIs hinder metal corrosion in HCl solutions but do it much more weakly in H2SO4, HClO4, and H3PO4. A known method for improving the protective effect of N-containing six-membered heterocyclic CIs in these media involves combining them with anionic additives, e.g., halide or rhodanide anions. The heterocycles discussed behave as CIs in “cold” solutions but lose these properties at higher temperatures. Examples of the use of six-membered N-containing heterocycles as CIs of various steels and non-ferrous metals (Al, Cu, Sn, Zn and their alloys) are available in literature. The industrial application of individual six-membered N-containing heterocycles and their derivatives for metal protection in acid media is of little promise and is unjustified. It is more appropriate to use these compounds as components of inhibitor mixtures. Mixed CIs containing these compounds can hinder corrosion even in such corrosive media as high-temperature HCl solutions or hot H3PO4 solutions. The base for creating prospective mixed corrosion inhibitors for metals in acids should be searched for among six-membered heterocyclic compounds containing two or more nitrogen atoms or compounds obtained from natural raw materials. The bibliography includes 150 references.

Int. J. Corros. Scale Inhib., , 4, 460-497 PDF (1 205 K)
doi: 10.17675/2305-6894-2018-7-4-1

Quantum chemical studies on inhibition activities of 2,3-dihydroxypropyl-sulfanyl derivative on carbon steel in acidic media

  • and
1 Department of Pure and Applied Chemistry, Ladoke Akintola University of Technology, P.M.B. 4000, Ogbomoso, Oyo State, Nigeria
2 Department of Chemistry, University of Ibadan, P.M.B. 5116, Ibadan, Oyo State, Nigeria

Abstract: The inhibiting activity of 3 sets of organic compounds ([2-[(2,3-dihydroxypropyl)sulfanyl]-N-octylacetamide (DSO), 2-[(2,3-dihydroxypropyl)sulfanyl]-N-decylacetamide (DSD) and 2-[(2,3-dihydroxypropyl)sulfanyl]-N-dodecylacetamide (DSDD)) were studied. The studied anti-corrosion compounds i.e. 2,3-dihydroxypropyl-sulfanyl derivatives were calculated using quantum chemical calculation and several descriptors (highest occupied molecular orbital energy (EHOMO), lowest unoccupied molecular orbital energy (ELUMO) and chemical reactivity indices (global electrophilicity index (ω), chemical hardness (η), electronegativity (χ), local reactivity index, electron affinity and ionization potential) which described the anti-corrosion properties of the studied compounds were obtained. Fukui Indices for nucleophilic and electrophilic Attacks for inhibitors i.e. [2-[(2,3-dihydroxypropyl)sulfanyl]-N-octylacetamide (DSO), 2-[(2,3-dihydroxypropyl)sulfanyl]-N-decylacetamide (DSD) and 2-[(2,3-dihydroxypropyl)¬sulfanyl]-N-dodecylacetamide (DSDD) were observed and sites for nucleophilic and electrophilic attacks for DSO were C6 (0.047) and O3 (0.170); for DSD, the utmost value for fk+ was found on C6 (0.047), and the highest value for fk- was located on C5 with 0.099 while the greatest value for fk+ was situated on C6 with 0.047 and the highest value for fk- is found on C3 and C4 with 0.053 each for the DSDD molecule. The molecules used in this study was calculated using quantum chemical calculation and it was achieved using Spartan 14. More so, the QSAR study using multiple linear regression method was executed using Gretl 1.9.8. The selected descriptors among the entire calculated descriptors were used in the development of quantitative structural activity relationship (QSAR) model and the developed model replicated the observed %IE. The correlation coefficient (R2) was calculated to be 0.926, cross validation (CV.R2) was 0.963 and adjusted R2 was 0.852. Also, ELUMO was the predominating parameter in the corrosion inhibition property of the studied compounds.

Int. J. Corros. Scale Inhib., , 4, 498-508 PDF (1 044 K)
doi: 10.17675/2305-6894-2018-7-4-2

Experimental, quantum chemical studies of oxazole derivatives as corrosion inhibitors on mild steel in molar hydrochloric acid medium

  • , , , , , , , and
1 Laboratory of Engineering, Electrochemistry, Modeling and Environment (LIEME), Faculty of Sciences, University Sidi Mohamed Ben Abdellah, Fez, Morocco
2 Laboratory of organical Chemistry (LOC), Faculty of sciences, University Sidi Mohamed Ben Abdellah, Fez, Morocco
3 Laboratory of Applied Analytical Chemistry Materials and Environment (LC2AME), Faculty of sciences, University of Mohammed Premier, Oujda, Morocco

Abstract: The corrosion inhibition performances of (4-ethyl-2-phenyl-4,5-dihydro-1,3-oxazol-4-yl)-methanol (C1); 4-{[(4-ethyl-2-phenyl-4,5-dihydro-1,3-oxazol-4-yl)methoxy]methyl}-benzene-1-sulfonate (C2) and 4-[(azidoxy)methyl]-4-ethyl-2-phenyl-4,5-dihydro-1,3-oxazole (C3) mild steel in molar hydrochloric solution have been evaluated by using gravimetric, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques as well as quantum chemical calculations. Results obtained reveal that these compounds reduce significantly the corrosion rate of mild steel, their inhibition efficiencies increased with inhibitor concentration. This behavior means that the inhibitive effect of the studied oxazole derivatives occur through the adsorption of inhibitor molecules on the metal surface. Polarization curves reveal that both compounds C1 and C3 act essentially as mixed type inhibitors with cathodic predominance effect, while the compound C2 can be classified as cathodic type inhibitor. EIS spectra obtained show a typical Nyquist plot with single semicircles shifted along the real impedance of x-axis. Impedance data are analyzed in term of the simple modified Randles equivalent circuit with one relaxation time constant. Indeed, a Constant phase element, CPE, is introduced in the circuit instead of a pure double layer capacitor in order to take into account the electrode surface heterogeneity. Adsorption of these inhibitors on the mild steel surface was found to obey the Langmuir adsorption isotherm. Some thermodynamic parameters were calculated and discussed. The correlation between inhibition efficiency and molecular structure of oxazole derivatives was theoretically studied via quantum chemical calculations using density functional theory (DFT) at B3LYP/6-31G (d,p). Results showed a general correlation between the computed descriptors and the experimental data.

Int. J. Corros. Scale Inhib., , 4, 509-527 PDF (1 213 K)
doi: 10.17675/2305-6894-2018-7-4-3

Influence of the acidity of the medium and the activity of chloride ions on kinetics of partial electrode reactions on steel with a superhydrophobic surface in chloride media

  • , , and
1 Tambov State Technical University, ul. Sovetskaya, 106, Tambov, 392000, Russian Federation
2 All-Russian Scientific Research Institute of Use of Machinery and Oil Products, Novo-Rubezhnyi per., 28, Tambov, 392022, Russian Federation
3 Derzhavin State University, ul. Internatsyonalnaya, 33, Tambov, 392000, Russian Federation
4 Angara GmbH, In der Steele 2, D-40599, Düsseldorf, Germany

Abstract: The electrochemical behavior of carbon steel with a superhydrophobic surface in weakly acid solutions with a constant ionic strength equal to 1 and a complex composition of the electrolyte x M HCl + (1–x) M NaCl with x = 0.0005–0.01 mol/L has been studied. The effect of the concentration (activity) of Cl anions was evaluated in NaCl solutions with variable concentrations in the range 0.0005–0.01 mol/L of the salt. To obtain a superhydrophobic coating, the metal surface was textured by IR laser radiation of nanosecond duration followed by chemisorption of MAF (methoxy-{3- [2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-pentadecafluorooctyl)oxy]propyl}silane from a solution of n-decane. The thickness of the superhydrophobic coating, including the textured metal layer and the adsorbed nanosize layer of the superhydrophobization agent (2–3 nm), was of the order of 100 μm. The wetting angle is 168.8±1.5°. The kinetic parameters of the hydrogen evolution reaction, accompanied by cathodic reduction of dissolved oxygen, and anodic ionization of the metal as a function of the acidity of the medium were obtained. With increasing duration of exposure, corrosion potential (Ecor) shifts to the region of more negative potentials and the most negative Ecor is observed at minimal HCl concentration. The steady state is achieved only after 120 hours and the corrosion potentials of the steel that corrodes in the active state assumes very negative values (–0.550 to –0.580 V) due to inhibition of the cathodic reaction. In media containing 0.0005–0.01 mol/L sodium chloride, the relationship between the kinetic parameters of the same electrode reactions and the activity of chloride ions (aCl-) has been studied. The anodic reaction is accelerated and the corrosion rate of the steel increases with an increase in the activity of chloride ions (1.0≤d lg ia/d lg aCl-≤2, 1.0≤d lg icor/d lg aCl-≤1.3). This may be a consequence of the participation of halogen anions in the anodic process.

Int. J. Corros. Scale Inhib., , 4, 528-541 PDF (827 K)
doi: 10.17675/2305-6894-2018-7-4-4

Inhibitory performance of some pyrazole derivatives against corrosion of mild steel in 1.0 M HCl: Electrochemical, MEB and theoretical studies

  • , , , , , and
1 Laboratoire d’Ingénierie d’Electrochimie de Modélisation et d’Environnement (LIEME) FSDM Fès, Morocco
2 Laboratoire National de Contrôle des Médicaments, D M P, Ministère de la Santé, Madinat Al Irnane, BP 6206, Rabat, Morocco

Abstract: In this study, we discussed the inhibition properties of three new Pyrazole derivatives (DPA, DPM and DPF) against the corrosion of mild steel in 1.0 M HCl, using the weight loss technique, the stationary method and the transitional method. The experimental results show that the inhibition properties increase with the concentration and can reach a limit value of 97% for the inhibitor DPA at 10–3 M. The curves of polarization show that the Pyrazole derivatives were a mixed inhibitor. The data obtained by electrochemical impedance spectroscopy were analyzed to be modeled by appropriate equivalent circuit models. The evolution of the temperature leads to a decrease in the inhibition efficiency of the Pyrazole compounds. Several adsorption isotherms have been modeled such as Langmuir, Temkin, Frumkin, Flory–Huggins, Freundlich and the kinetic thermodynamic model of El-Awady, in order to provide additional information on the inhibitory properties of the compounds studied. The coefficient of determination values of all the isotherms are very high, from the two models of Flory–Huggins and El-Awady we find that the adsorption of molecules on the surface of the steel moves more than a single molecule of water which is at odds with the Langmuir isotherm. Whereas the isotherms of Temkin and Frumkin suggest the existence of the lateral interactions between the adsorbed species. Scanning electron microscopy (SEM) and EDX analyzes were used to characterize the chemical composition of the film formed on the surface of the steel. Surface studies have shown that the inhibitory layer consists of an iron oxide/hydroxide mixture in which the N, F atoms are incorporated. The DFT studies have also been carried out for protonated form of the inhibitor molecules by considering that in acidic medium the heteroatoms of organic inhibitors easily undergo protonation. The experimental and density functional theory (DFT) studies were in good agreement.

Int. J. Corros. Scale Inhib., , 4, 542-569 PDF (1 608 K)
doi: 10.17675/2305-6894-2018-7-4-5

Influence of water-soluble monomers on the corrosion protection ability of chromium coatings obtained from Cr(III)-based solutions

  • and
1 Dmitry Mendeleev University of Chemical Technology of Russia, Miusskaya sq., 9, Moscow, 125047 Russian Federation
2 A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Leninskii pr., 31, Moscow, 119071 Russian Federation

Abstract: The effect of water-soluble electropolymerizable monomer additives in Cr(III) sulfate–oxalate electrolytes on the corrosion–electrochemical behavior of chromium coatings and their ability to protect the steel support is studied. The additives into the Cr(III) sulfate–oxalate electrolytes were caprolactam, aniline, and acrylamide. The XPS technique showed that both the surface and bulk layers of chromium coatings obtained from electrolytes with additives contain products of chemical or electrochemical conversions of caprolactam, aniline, and acrylamide, including their polystructures. It is found that caprolactam and aniline produce a positive effect on the protective ability of chromium coatings, while the protective ability of chromium coatings in the presence of acrylamide decreases. These properties are determined primarily by a decrease in the number of defects in chromium coatings in case of caprolactam and aniline and an increase in the number of cracks in the deposits in case of acrylamide. According to the earlier studies, the corrosion–electrochemical behavior of chromium coatings from Cr(III) sulfate–oxalate electrolytes in 0.5 M H2SO4 is determined primarily by the presence of the chromium carbide phase acting as a cathodic agent. The effect of additives on the anodic polarization curve in 0.5 M H2SO4 is most probably determined not only by an increase or decrease in the porosity of chromium deposits, but also by incorporation of the additives and products of their electrochemical conversion that, according to the literature, can act as corrosion inhibitors.

Int. J. Corros. Scale Inhib., , 4, 570-581 PDF (1 139 K)
doi: 10.17675/2305-6894-2018-7-4-6

Peculiarities of the effect of secondary amines with cyclic substituents on microbial steel corrosion

  • , , , , and
1 T.H. Shevchenko National University “Chernihiv Colehium”, 53 Hetmana Polubotka str., Chernihiv, 14013, Ukraine
2 National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”, 37 Peremohy Ave, Kyiv, 03056 Ukraine
3 Ukrainian State University of Chemical Technology, ave. Gagarin, 8, 49005, Dnipro, Ukraine

Abstract: The effect of secondary amines with cyclic substituents (triazoloazepine, unsubstituted phenyl or substituted phenyl ones) on the microbial corrosion of low-carbon steel induced by sulfate-reducing bacteria isolated from various technogenic media was studied. The compounds were obtained by reactions of 7-methoxy-3,4,5,6-tetrahydro-2H-azepine with hydrazides of substituted N-arylaminoacetic acids. It was found by gravimetric and electrochemical methods that secondary amines with p-methoxyphenyl and p-chlorophenyl substituents hinder steel corrosion in the neutral Postgate “B” water-salt medium, both in the presence of enrichment bacterial culture and the Desulfovibrio sp. M.4.1 strain. The highest inhibitive effect (a 2.13-fold corrosion rate decrease) is shown by the compound with the p-chlorophenyl substituent. It has been shown that the effect of concentration within 0.5–2.0 g/l on the efficiency of biocorrosion inhibition is insignificant. The results obtained were explained by the antimicrobial action of secondary amines on sulfate-reducing bacteria and their satellites (iron-reducing and denitrifying bacteria). Using energy dispersive spectroscopy, it has been shown that secondary amines studied can be adsorbed adsorb on mild steel surface under conditions of microbial corrosion in a water-salt medium with bacterial sulfate reduction. The surface layers were found to contain nitrogen contained in the elementary composition of the compounds, as well as chlorine in the case of the secondary amine with the p-chlorophenyl substituent. It has been found that the biofilm (a polymeric matrix consisting of bacterial excrements and corrosion products) is formed atop the film of adsorbed compounds. The inhibition effect is ensured only upon adsorption of compounds with antimicrobial properties toward sulfate-reducing bacteria. If secondary amines have no antimicrobial properties toward sulfate-reducing bacteria, iron sulfides are formed on the metal surface and microbial corrosion is accelerated.

Int. J. Corros. Scale Inhib., , 4, 582-592 PDF (1 036 K)
doi: 10.17675/2305-6894-2018-7-4-7

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