ISSN 2305-6894

2015, Vol. 4, Issue 4 (pp. 284-394)

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

  • Yu. I. Kuznetsov
A. N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Leninskii pr. 31, Moscow, 119071 Russian Federation

Abstract: A survey of studies on the adsorption of organic corrosion inhibitors (CIs) on metals from acid and neutral solutions for the period 2005–2015 is presented. It is noted that in order to estimate the adsorption of CI in corrosive acid solutions, the electrochemical impedance spectroscopy method (EIS) remains the most valuable. However, even the use of EIS for building CI adsorption isotherms is an approximation, which demands selecting the optimum conditions to reduce errors (control electrode potential, minimizing the rate of electrode dissolution, etc.). Besides, the conclusions about the state of the adsorption system and mechanism of adsorption of chemical substances can be made, at least, based on results of determining both the adsorption energy and the adsorption process kinetics. Addition of such a study to measure the aftereffect and XPS studies of the protective film formed on the metal by a CI provides valuable information about the nature of its adsorption. In reviewing studies of CI adsorption in neutral aqueous solutions, much attention is paid to the in situ ellipsometry method. It is noted that the best conditions for such investigations may be produced on the surfaces of electrodes at potentials corresponding to the absence of intense cathodic hydrogen evolution or anodic dissolution of the metal. Examples of CI adsorption measurements by other in situ methods (EIS and electrochemical quartz microbalance, EQMB), the results of which are consistent with those of ellipsometry, are discussed. Results of successful application of ellipsometry in combination with the XPS studies of protective layers on various metals in the study of not only individual CIs but also mixtures thereof are provided. Ellipsometric studies have played an important role in the discovery of a new possibility of using CIs, which consists in successive formation of adsorption layers of different CIs on a metal (layer-by-layer coating).

Int. J. Corros. Scale Inhib., , 4, 284-310 PDF (604 K)
doi: 10.17675/2305-6894-2015-4-4-1

Mixed-surfactant aggregation, adsorption, and associated steel corrosion inhibition in salt solution

Metallurgical Engineering, University of Utah, 135 S 1460 E, Rm 412, Salt Lake City, UT, 84112, USA

Abstract: The corrosion inhibition efficiency of mixtures of three homologous benzalkonium chlorides (BAC) surfactants was investigated using electrochemical measurements and modeling. The surface aggregation concentration (sac) and critical micelle concentration (cmc) of surfactant are useful to evaluate inhibition efficiency. A new cmc prediction model for ternary mixed homologous surfactants of interest has been developed. The model is applicable over a wide concentration range of dissolved salt in solution. The combination of the modified Langmuir adsorption model and the cmc prediction model provides a potential method for inhibition efficiency prediction of various mixed homologous surfactant systems at various dissolved salt concentrations.

Int. J. Corros. Scale Inhib., , 4, 311-327 PDF (1 301 K)
doi: 10.17675/2305-6894-2015-4-4-2

Piezogravimetric investigation of heterocyclic compounds as potential inhibitors against copper corrosion in acidic media

  • , and
1 Functional Interfaces Group, Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, H. A. S., 1117 Budapest, Magyar tudósok körútja 2, Hungary
2 University of Novi Sad, Faculty of Sciences, Serbia

Abstract: Corrosion and inhibition processes can be followed by different in-situ methods at a nanometer scale. In this contribution, the corrosion breakdown potentials and inhibition efficiencies were evaluated using the electrochemical quartz crystal nanobalance (EQCN) technique, by recording linear potential scan for voltammetric (i–E) and piezogravimetric (m–E) characteristics. The effectiveness of thiazole derivatives, in an aggressive solution of 0.1 M Na2SO4, on the value of the breakdown potential of the copper electrode, was investigated. The investigated thiazole derivatives are: 5-benzylidene-2,4-dioxo tetrahydro-1,3-thiazole (5-BDT) 5-(4´-isopropylbenzylidene)-2,4-dioxotetrahydro-1,3-thiazole (5-IPBDT), 5-(3´-thenylidene)-2,4-dioxotetrahydro-1,3-thiazole (5-TDT) and 5-(3´,4´-dimetoxybenzylidene)-2,4-dioxotetrahydro-1,3-thiazole (5-MBDT). The inhibitor effectiveness was monitored and corrosion rates were determined. Previously found effects for some of the thiazole derivatives were confirmed. The most effective, among the tested thiazole derivatives against copper corrosion, was 5-IPBDT, due to the presence of the isopropyl functional group.

Int. J. Corros. Scale Inhib., , 4, 328-337 PDF (909 K)
doi: 10.17675/2305-6894-2015-4-4-3

Breakdown of passivity of nickel electrode in sulfuric acid and its inhibition by pyridinone derivatives using the galvanostatic polarization technique

  • , , and
1 Chemistry Department, Faculty of Science, Umm Al-Qura University, Makkah Al Mukaramh, Saudi Arabia
2 Chemistry Department, Faculty of Science, Banha Univeristy, Banha, Egypt
3 Chemistry Department, Faculty of Science, Zagazig Univeristy, Zagazig, Egypt

Abstract: The effect of Cl and Br anions as aggressive species to breakdown the passivity of Ni electrode in H2SO4 solution was studied using galvanostatic polarization technique. Low concentrations of these anions lower than 1×10–4 M have no effect on the passivity of nickel, while high concentrations of these anions destroy the passivity and initiate the pitting potential before the oxygen evolution region. Raising the solution temperature shifts the breakdown potential towards the more negative direction. This could be attributed to the more destruction of the passivity by halides anions with increasing temperature. The addition of some synthetic pyridinone derivatives to the aggressive chloride solutions shifts the pitting potential to more positive values indicating the resistance to pitting attack in chloride containing solution.

Int. J. Corros. Scale Inhib., , 4, 338-352 PDF (1 269 K)
doi: 10.17675/2305-6894-2015-4-4-4

The influence of alkalising amines on the film formation by oleyldiamine

  • , and
1 Kurita Europe APW GmbH, Giulinistraße 2, 67065 Ludwigshafen, Germany
2 Kurita France SAS, Z. I. Le Roineau, 72500 Vaas, France

Abstract: The film formation of film forming amines (FFAs), commonly used as corrosion inhibitors in water/steam cycles, has been subject of various studies. However, less is known of the impact of alkalising amines (AA) on the film formation. AAs have a solubilising effect on the FFA and as a consequence might indirectly influence the properties of the film. Therefore, the film formation of oleyldiamine, a commonly used FFA, on carbon steel has been studied with electrochemical impedance spectroscopy (EIS) in defined test water, containing 200 mg L–1 of NaCl, with and without the presence of different AAs. The studies have been carried out at two different pH values over an exposure time up to 5 h. All EIS spectra of the blank show one semi-circle, whereas two distinct semi-circles have been observed in the spectra of the test solutions with FFA. Therefore, the steel solution interface has been described by two different equivalent circuits using resistances and constant phase elements. All EIS spectra could be fitted with good agreement to the experimental data. The spectra showed significant and systematic changes throughout the exposure time. All polarisation resistances measured with FFA at pH 9.0 are much higher compared to the data obtained at pH 8.2. The polarisation resistance of the blank solution is strongly decreasing over time following roughly an exponential law and almost comes to a steady state after 5 hours. In contrast to this the solutions containing FFA show a linear increase of the polarisation resistance over time. Obviously the film formation has not yet completely been finished within the experimental period. The FFA solutions containing the two different AA show a similar behaviour over time and almost the same high polarisation resistance, reflecting the excellent corrosion protection. Overall, the data indicate that the film obtained with oleylamine in the solutions containing DEAE provides a slightly better protection than FFA solution with CHA. Thus, the more toxic CHA can be replaced by DEAE.

Int. J. Corros. Scale Inhib., , 4, 353-364 PDF (1 179 K)
doi: 10.17675/2305-6894-2015-4-4-5

Adsorption and corrosion inhibiting behavior of Passiflora foetida leaf extract on mild steel corrosion

  • , , , and
1 Department of Chemistry, Thiagarajar College, Madurai, India
2 Department of Civil Engineering, Fatima Michael College of Engineering and Technology, Madurai, India
3 Department of Chemical Engineering, National Taipei University of Technology, Taiwan

Abstract: Passiflora foetida leaf extract (PFLE) as a corrosion inhibitor in 1 M HCl was investigated by weight loss method and electrochemical techniques. Inhibition efficiency of PFLE was found to increase with increasing concentration. Polarization measurements revealed that the PFLE acted as a mixed type inhibitor. Nyquist plots showed that on increasing the PFLE concentration, the charge transfer resistance increased and double layer capacitance decreased. The adsorption of PFLE on mild steel obeyed the Langmuir adsorption isotherm. The maximum inhibition efficiency was found to be 94.61% at 313 K in the presence of 130 ppm of PFLE. SEM and AFM techniques confirmed the adsorption of PFLE on mild steel surface.

Int. J. Corros. Scale Inhib., , 4, 365-381 PDF (1 196 K)
doi: 10.17675/2305-6894-2015-4-4-6

Study of the temperature effect on electrochemical impedance spectra in presence of an inhibitor

  • , , and
1 Department of Physical Chemistry, University of Chemical Technology and Metallurgy, 8 Kl. Ohridski Blvd., 1756 Sofia, Bulgaria
2 Faculty of Chemistry, University of Sofia, 1 J. Baucher Ave, 1126 Sofia, Bulgaria

Abstract: The inhibitive properties of a quaternary ammonium salt displayed in case of mild steel corrosion in 1 M HCl are studied in the temperature range of 30–60°C. Electrochemical impedance spectroscopy and polarization resistance method are applied. A structural model describing the processes at the interface is advanced and its parameters are estimated. The data on the temperature effect in inhibitor’s presence and absence are juxtaposed. An interpretation of the results obtained is suggested.

Int. J. Corros. Scale Inhib., , 4, 382-393 PDF (1 251 K)
doi: 10.17675/2305-6894-2015-4-4-7

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