ISSN 2305-6894

2017, Vol. 6, Issue 3 (in progress)

Organic corrosion inhibitors: where are we now? A review. Part III. Passivation and the role of the chemical structure of organophosphates

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

Abstract: This article continues the review of studies (2006–2016) dealing with the passivation of various metals by solutions of organic corrosion inhibitors. It provides an overview of papers on the passivating properties of organophosphates, their complexes and salts. The results of corrosion and electrochemical studies, as well as studies on the composition and structural features of surface layers on metals by a variety of physicochemical methods are considered.

Int. J. Corros. Scale Inhib., 2017, 6, no. 3, 209-239 (PDF 1258 K)
doi: 10.17675/2305-6894-2017-6-3-1

The inhibition effect of o-nitrophenol and Zn2+ system
on corrosion of aluminium

      • D. Lakshmi,1 J. Sathiyabama2 and S. Rajendran2,3
1Department of Chemistry, M.V. Muthiah Government Arts College for Women, Dindigul-624001, Tamil Nadu, India
2Department of Chemistry, G.T.N.Arts College, Dindigul-624004, Tamil Nadu, India
3Department of Chemistry, St.Antony’s college of arts and sciences for women, Dindigul-624005, Tamil Nadu, India

Abstract: Corrosion inhibition of aluminum (6061) in aqueous solution at pH 11 by o-nitrophenol–Zn2+ systems has been reported. The study was carried out using classical weight loss method, potentiodynamic polarization study and Fourier Transform Infra-red Spectrocopy (FTIR) Technique. Experimental results indicated that the presence of o-nitrophenol–Zn2+ inhibit the corrosion of Al(6061). The inhibition efficiency (IE) has been determined by the classical weight loss method. The maximum inhibition efficiency offered by the o-nitrophenol 250 ppm and Zn2+ 50 ppm system is 94%. To determine the values of Linear polarization resistance (LPR) and corrosion current (Icorr), potentiodynamic polarization study has been used and it reveal that the inhibitor act as anodic inhibitor and it controls the anodic reaction. The protective film has been characterized by FTIR, SEM, EDAX and AFM. The protective film consists of Al3+–o-nitrophenol complex on the anodic metal surface. By using Density Functional Theory (DFT) various quantum chemical parameters such as EHOMO (highest occupied molecular orbital energy), ELUMO (lowest unoccupied molecular orbital energy), energy gap (ΔE), electron affinity (A), ionization potential (I), absolute electronegativity (χ), global hardness (η), softness (S), fraction of electrons transferred (ΔN) have been calculated and discussed. The theoretical results were found to be consistent with the experimental data generated. The inhibition efficiency of the inhibitor is evaluated by weight loss method.

Int. J. Corros. Scale Inhib., 2017, 6, no. 3, 240-261 (PDF 1806 K)
doi: 10.17675/2305-6894-2017-6-3-2

Laboratory assessment of inhibition efficiency and mechanism
of inhibitor blend (P22SU) on mild steel corrosion in high chloride containing water

      • A. Shaban,1 I. Felhosi1 and J. Telegdi1,2
1 Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, H-1117, Magyar tudósok körútja 2, Bp., Hungary
2 Óbuda University, Faculty of Light Industry and Environmental Engineering, H-1034, Doberdó u. 6., Bp., Hungary

Abstract: The corrosion inhibition process of phosphonic-acid based inhibitor blends (Corin P22SU), on mild steel corrosion in simulated cooling water (SCW) containing chloride ion has been investigated using electrochemical methods (impedance spectroscopy (EIS), open circuit potential (OCP) and visual characterization). The synergistic effect on the inhibition efficiency of the commercially produced (Corin P22SU) inhibitor with different concentrations of nitrite was examined. Inhibition activity increases with the increase of Corin P22SU concentration. The experimental parameters were concentration of the inhibitor, and soaking time. P22SU inhibits mild steel corrosion in near neutral and alkaline (pH ≤ 6) SCW. Inhibitive action was increased with the increase of soaking time up to six hours and afterwards. Based on the experimental results, mechanisms of action of Corin P22SU on mild steel corrosion inhibition in SCW have been proposed.

Int. J. Corros. Scale Inhib., 2017, 6, no. 3, 262-275 (PDF 1517 K)
doi: 10.17675/2305-6894-2017-6-3-3

Kinetic and morphological investigation of calcium sulfate dihydrate (gypsum) scale formation on heat exchanger surfaces in the presence of inhibitors

      • Z. Amjad
Walsh University, Department of Chemistry, Division of Mathematics and Sciences, 2020 E. Maple Street, North Canton, Ohio 44720

Abstract: The kinetics of calcium sulfate dihydrate (CaSO4·2H2O, gypsum) scale formation on heated metal surface from aqueous solution has been studied by a highly reproducible technique. It has been observed that gypsum growth takes place directly on heated metal surface without any bulk or spontaneous precipitation in the supersaturated solution. A variety of maleic acid based polymers with different functional groups have been examined for their inhibitory effect on gypsum growth. The results indicate that amount of gypsum scale formed on heated metal surface is strongly affected by polymer dosage and the functional groups present in the polymer. Scanning electron microscopic investigations of the gypsum crystals grown in the presence of anionic polymeric additives show that structures of these crystals are highly modified. Results on the performance of various surfactants and biocides are presented.

Int. J. Corros. Scale Inhib., 2017, 6, no. 3, 276-290 (PDF 2035 K)
doi: 10.17675/2305-6894-2017-6-3-4

Anthocyanins as a corrosion inhibitor for 2024-T3 aluminum alloys: a study of electrochemical behavior

      • A. Petersen, S.R. Rodrigues, V. Dalmoro, T. Falcadea and S.M. Tamborim
Post-Graduate Program in Chemistry, Federal University of Rio Grande do Sul, Avenida Bento Gonçalves, 9500, Porto Alegre, Brasil

Abstract: Grape anthocyanin efficiency as a corrosion inhibitor for 2024-T3 aluminum alloy was evaluated by electrochemical techniques such as, electrochemical impedance spectroscopy and cathodic and anodic potentiodynamic polarization. The inhibitor behavior for 2024-T3 aluminum alloy was investigated in 800, 1000, 2000, 3000, 5000 and 7200 ppm of the grape anthocyanin solution in the presence of 0.025 mol·L–1 NaCl. According to electrochemical impedance spectroscopy results, the measured point dispersion in the low frequencies region decreased when the 2024-T3 aluminum alloy immersion time in the grape anthocyanin solution increased from 1 h to 3 days. It was also observed for samples after 3 days immersion that there was a reduction in the inductive behavior in the same region, and a considerable increase in the polarization resistance and inhibition efficiency for the 1000 ppm grape anthocyanin sample. Under anodic and cathodic polarization a generally better performance was also observed in the anticorrosive properties as potential and current corrosion and anti-corrosion protection efficiency for the above mentioned concentration sample. The grape anthocyanin adsorption characteristics, on the AA2024-T3 indicated similar behavior to Langmuir isotherm.

Int. J. Corros. Scale Inhib., 2017, 6, no. 3, 291-306 (PDF 2084 K)
doi: 10.17675/2305-6894-2017-6-3-5

SVET study of the interaction of 2-mercaptobenzothiazole corrosion inhibitor with Au, Cu and Au–Cu galvanic pair

      • J.A. Ramírez-Cano,1 L. Veleva,1 B.M. Fernández-Pérez2 and R.M. Souto2
1Department of Applied Physics, Centre for Investigation and Advanced Studies (CINVESTAV), km. 6 Carr. Antigua a Progreso, AP 73, Cordemex, 97310 Merida, Yucatan, Mexico
2Department of Chemistry, Universidad de La Laguna, P.O. Box 456, 38200 La Laguna, Tenerife, Canary Islands, Spain

Abstract: This study reports an electrochemical investigation of the interaction between 2-mercaptobenzothiazole (2MBT), a corrosion inhibitor, and two noble metals (Cu and Au), either isolated or under galvanical coupling. The surface reactivity of the inhibitor-modified metals in chloride-containing aqueous solution of 0.1 mM NaCl was studied using the Scanning Vibrating Electrode Technique (SVET). The potential gradients in the electrolyte were detected by the SVET and converted to local ionic currents distributed at different anodic and cathodic sites, where electrochemical redox reactions are taking place. No external polarization was applied during SVET measurements, leaving the samples at the spontaneous free corrosion potential (FCP). The values of FCP showed that the metals are not protected by 2MBT. SVET revealed a moderate electrochemical activity of Au and very low in the case of Cu.

Int. J. Corros. Scale Inhib., 2017, 6, no. 3, 307-317 (PDF 1328 K)
doi: 10.17675/2305-6894-2017-6-3-6