scholarly journals Corrosion of low-carbon steel in sodium chloride solution containing a water-soluble fraction of humic acid

2021 ◽  
Author(s):  
Leoš DOSKOČIL ◽  
Tomáš HORÁK ◽  
Jiří HONČ
2020 ◽  
pp. 2050038
Author(s):  
QIONGWEI LI

Pitting corrosion of carbon steel in sodium chloride solution induced by Ce[Formula: see text] and the synergistic inhibition effects of Ce[Formula: see text] and Zn[Formula: see text]/SiO[Formula: see text] were investigated using in-situ observation and electrochemical methods. The results showed that the presence of Ce[Formula: see text] could result in severe pitting corrosion and a positive shift in the corrosion potential. It was found that individual Ce[Formula: see text], Zn[Formula: see text], or SiO[Formula: see text] had low inhibition efficiencies, whereas the combination of Ce[Formula: see text] and Zn[Formula: see text] or SiO[Formula: see text] proved to be highly effective in inhibiting the development of pits in two different ways and in enhancing the corrosion resistance. The pitting corrosion and inhibition mechanisms were discussed based on the results.


Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5392
Author(s):  
Yongyan Zhu ◽  
Jiayi Ding ◽  
Jianli Zhang ◽  
Liang Li

In this paper, effects of sodium phosphate (Na3PO4) and sodium nitrite (NaNO2) on the pitting corrosion of X70 carbon steel in 0.10 mol/L NaCl solution were investigated by potentiodynamic polarization technique, electrochemical impedance spectroscopy (EIS) method, scanning electron microscope (SEM) and scanning electrochemical microscope (SECM). The SECM equipment was used to observe the dynamic processes of the pitting corrosion in situ. Na3PO4 or NaNO2 in the sodium chloride solution decreased the local anodic dissolution and increased the pitting resistance of the specimen. By analysis and comparison, it can be concluded that the inhibition effect of Na3PO4 is mainly due to the formation of a salt film, while the corrosion inhibition of NaNO2 is principally attributed to a protective oxide film on the electrode surface.


Author(s):  
N. E. Kobzar ◽  
V. P. Mikhailov ◽  
V. V. Porseva

Introduction. Methyl-β-cyclodextrin is a potent acceptor of cellular membrane cholesterol and, at the same time, used as a solubilizer, which makes it a potential target for targeted delivery of hydrophobic compounds.Aim. To assess the effect of administration of methyl-β-cyclodextrin containing cholesterol on the degree of lung hydration and osmotic resistance of erythrocytes against the background of pulmonary edema in adult rats caused by the administration of mezaton.Materials and methods. We investigated the degree of hydration of the lungs by the value of the pulmonary coefficient and their dry residue. Osmotic resistance of erythrocytes were assessed by the intensity of their hemolysis in a series of hypotonic sodium chloride solutions in adult male Wistar rats (220±40 g) of the control group (intact, n=10) and two experimental groups with pulmonary edema caused by the administration of mezaton (n=10) and with the subsequent introduction of a water-soluble complex cholesterol-methyl-β-cyclodextrin against the background of the development of pulmonary edema (n=10). We used additional criteria for assessing the osmotic resistance of erythrocytes: minimum resistance – the concentration of sodium chloride solution, at which the first “weak” erythrocytes begin to hemolyze; maximum resistance is the concentration of sodium chloride solution at which all or almost all erythrocytes hemolyzed.Results. The introduction of mezaton led to the development of pronounced hemolysis and hydration of the lungs with the development of their edema and a narrowing of the range of minimum and maximum osmotic resistance of erythrocytes. The introduction of a complex of cholesterol with methyl-β-cyclodextrin after edemogenic exposure led to a decrease in the severity of pulmonary edema, determined by a decrease in the pulmonary coefficient and an increase in the dry residue, and to an increase in the osmotic resistance of erythrocytes with an expansion of the range of their minimum and maximum osmotic resistance.Conclusion. The introduction of a water-soluble complex of cholesterol with methyl-β-cyclodextrin against the background of the development of hemodynamic pulmonary edema significantly reduced the degree of hydration of the lungs, which combined with an increase in the osmotic resistance of erythrocytes.


2018 ◽  
Vol 149 ◽  
pp. 01050
Author(s):  
Mohammed Hassoune ◽  
Abdelillah Bezzar ◽  
Latéfa Sail ◽  
Fouad Ghomari

The inhibition of carbon steel corrosion in neutral sodium chloride solution by N,N'- Dimethylaminoethanol (DMEA), at different temperatures, was investigated using weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The results obtained confirm that DMEA is a good organic corrosion inhibitor for carbon steel in 0.5M of NaCl (concentration encountered in the Mediterranean seawater), over the whole range of temperatures studied. The inhibition efficiency (IE%) increases with increasing DMEA concentration; it reaches highest value for a concentration around 0.125 mol.L-1. Potentiodynamic polarization data show that, the compound studied in this research predominantly act as anodic-type inhibitor. The EIS study reveals that the addition of DMEA decreases the corrosion rate of carbon steel in neutral sodium chloride solution, due to the fact that the inhibitor molecules are strongly adsorbed on the active sites following Langmuir isotherm, thus leading to the formation of a stable protective film on the steel surface which is able to keep the metal/solution interface in a passive state. Furthermore, the values of the activation parameters, i.e. ΔHa and Ea obtained in this study indicate that the adsorption process of DMEA is endothermic and could be mainly attributed to chemisorption, respectively.


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