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The adsorption and inhibition effect of Ascorbyl palmitate (AP) on carbon steel in ethanol blended gasoline containing water as a contaminant (GE10+1%water) was studied by weight loss and electrochemical impedance spectroscopic (EIS) techniques. The results showed that the addition of ethanol and water to gasoline increase the corrosion rate of carbon steel. AP inhibits the corrosion of carbon steel in (GE10+1% water) solution to a remarkable extent. The adsorption of AP on the carbon steel surface was found to obey the Langmuir adsorption isotherm model. The values of activation energy (Ea) and various thermodynamic parameters were calculated and discussed. © 2013 Elsevier Ltd.


Farag A.A.,Egyptian Petroleum Research Institute | Hegazy M.A.,Egyptian Petroleum Research Institute
Corrosion Science | Year: 2013

The inhibition effect of three Schiff bases (SB-I, SB-II and SB-III) and its synergistic effect with KI on the corrosion of carbon steel in 0.5M H2SO4 solution was studied by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. Scanning electron microscopy (SEM) was used to characterize the steel surface. The inhibition efficiency increases with the concentration of the Schiff bases and increased further with the presence of KI. The thermodynamic parameters Kads and δG°ads are calculated and discussed. The probable inhibitive mechanism is proposed from the viewpoint of adsorption theory. © 2013 Elsevier Ltd.


Deyab M.A.,Egyptian Petroleum Research Institute
International Journal of Hydrogen Energy | Year: 2013

The purpose of this paper is to describe and evaluate the corrosion of carbon steel in crotonic acid for hydrogen production and using polysorbate 20 (NS), dioctyl sodium sulfosuccinate (AS) and benzalkonium chloride (CS) to control hydrogen evolution. Measurements were conducted in tested solutions using hydrogen evolution and electrochemical impedance spectroscopy (EIS) measurements and complemented by scan electron microscope (SEM) and energy dispersive X-ray (EDX) investigations. It is shown that the hydrogen generation rate obtained during the corrosion of carbon steel in crotonic acid increased with increase in acid concentration, temperature and immersion time. The addition of organic surfactants inhibits the hydrogen generation rate. The inhibition occurs through adsorption of organic surfactants on the metal surface. Adsorption processes followed the Langmuir isotherm. The order of effectiveness of the surfactants was AS > NS > CS. The values of activation energy (Ea) and heat of adsorption (Qads) were calculated and discussed. Copyright © 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.


Deyab M.A.,Egyptian Petroleum Research Institute
Journal of Industrial and Engineering Chemistry | Year: 2015

The inhibition of copper corrosion in 0.1 M HCl by Egyptian licorice extract was investigated by dc polarization, ac impedance techniques. A significant decrease in the corrosion rate of copper in 0.1. M HCl was observed in the presence of licorice extract. The corrosion rate was found to depend on the concentration of licorice extract, temperature and extraction solvent composition. The adsorption of licorice extract on copper surface obeys Temkin isotherm. Polarization data indicated that the licorice extract acts as a mixed-type inhibitor. The values of activation energy for copper corrosion and various thermodynamic parameters were calculated and discussed. © 2014 The Korean Society of Industrial and Engineering Chemistry.


The effect of addition of carbon nanotubes (CNTs) on the corrosion resistance of conductive polymer coating (polyaniline) that coated aluminum bipolar plates in acidic environment inside the PEM fuel cell (0.1 M H 2SO4) was investigated using electrical conductivity, polarization and electrochemical impedance spectroscopy (EIS) measurements. Scanning electron microscopy (SEM) was used to characterize the coating morphology. The results show that the addition of CNTs to polyaniline coating enhanced the electrical conductivity and the corrosion resistance of polyaniline polymer. The inhibition efficiency of polyaniline polymer increased with increasing CNTs concentration. The best inhibition was generally obtained at 0.8% CNTs concentration in the acidic medium. This was further confirmed by decreasing the oxygen and water permeability and increasing coating adhesion in the presence of CNTs. EIS measurements indicated that the incorporation of CNTs in coating increased both the charge transfer and pore resistances while reducing the double layer capacitance. © 2014 Elsevier B.V. All rights reserved.


Tawfik S.M.,Egyptian Petroleum Research Institute
RSC Advances | Year: 2015

Biopolymer alginate surfactant derivatives were synthesized and their influences as a novel corrosion inhibitor on carbon steel in 1 M HCl were studied using gravimetric, electrochemical, EDX and SEM techniques. The compounds obtained were characterized using FTIR, 1H NMR and UV-vis spectroscopy studies. The inhibition efficiency increased with the increase in concentration and reached a maximum of 96.27% for AS-Cu at 5 × 10-3 M concentration. Potentiodynamic polarization results reveal that alginate derivatives could be classified as mixed-type corrosion inhibitors with predominant control of the cathodic reaction. The extent of inhibition exhibits a positive trend with an increase in temperature. The Langmuir isotherm provides the best description of the adsorption nature of the inhibitor. The results of EIS indicate that both the charge transfer resistance and inhibition efficiency tend to increase by increasing the inhibitor concentration. The thermodynamic parameter and activation parameters were calculated to investigate the mechanism of inhibition. Also, the relationship between the chemical structure and inhibition efficiency of the inhibitor was discussed. © The Royal Society of Chemistry 2015.


Three cationic Schiff surfactants namely; N,N-dimethyl-4-(((1-methyl-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)imino)methyl)-N-octylbenzenaminium bromide (APS-8); N,N-dimethyl-4-(((1-methyl-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)imino)methyl)-N-dodecyl benzenaminium bromide (APS-12) and N,N-dimethyl-4-(((1-methyl-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)imino)methyl)-N-hexadecylbenzenaminium bromide (APS-16) were synthesized and confirmed. The corrosion of carbon steel in 1.0 M HCl solution at 20-60 °C was studied by weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS). The results show that synthesized cationic surfactants are excellent inhibitors even with very low concentration, and the adsorption on carbon steel surface obeys Langmuir adsorption isotherm. Polarization curves reveal that the synthesized inhibitors behave as a mixed-type inhibitor. Adsorption of used inhibitors led to a reduction in the double layer capacitance and an increase in the charge transfer resistance. Thermodynamic and activation parameters were discussed. Calculated ΔG°ads values indicated that the adsorption mechanism of the prepared cationic surfactants on carbon steel in 1 M HCl solution is a chemical adsorption. © 2015 Elsevier B.V.


Hegazy M.A.,Egyptian Petroleum Research Institute
Journal of Molecular Liquids | Year: 2015

Abstract The corrosion inhibition effect of novel cationic surfactant based on tolyltriazole on carbon steel in 7 M H3PO4 solution has been evaluated by weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) methods. The inhibition efficiency increases with increasing inhibitor concentration, but it decreases with increasing the temperature. The adsorption of inhibitor is mixed physical and chemical adsorption and found to obey the Langmuir adsorption isotherm. Data obtained from EIS studies were analyzed to model inhibition process through appropriate equivalent circuit model. Potentiodynamic polarization studies have shown that the inhibitor acts as a mixed type of inhibitor. Scanning Electron Microscopy (SEM) study also confirmed the protection of the metal surface by the used cationic surfactant. © 2015 Elsevier B.V. All rights reserved.


Deyab M.A.,Egyptian Petroleum Research Institute
Journal of Power Sources | Year: 2015

Polyoxyethylene (40) nonylphenyl ether as nonionic surfactant (PNE) has been tested as an inhibitor for zinc corrosion in alkaline electrolyte (7.0 M KOH) via potentiodynamic polarization together with electrochemical impedance spectroscopy (EIS) measurements. The surface characterization of zinc has been examined with scanning electron microscopy (SEM) and confirmed by infrared spectroscopy (FTIR). The Results show that PNE surfactant inhibits zinc corrosion in 7.0 M KOH solution and indicate that the inhibition capability increases with the concentration of PNE surfactant. The maximum inhibition efficiency has been obtained near to critical micelle concentration of PEN surfactant (CMC = 0.25 mM). The battery containing PNE surfactant exhibits better performance. PNE surfactant works as a mixed type inhibitor by physical adsorption. This adsorption obeys Freundlich adsorption isotherm. © 2015 Elsevier B.V. All rights reserved.


Hydroxyethyl cellulose (HEC) has been investigated as corrosion inhibitor for zinc-carbon battery by polarization and electrochemical impedance spectroscopy (EIS) measurements. The obtained results show that the maximum inhibition efficiency by HEC in 26% NH4Cl solution at 300 ppm and 298 K is 92.07%. Tafel polarization studies reveal that HEC acts as an efficient mixed inhibitor. The corrosion rate is suppressed by the adsorption of HEC on the zinc surface. HEC adsorption obeys the Langmuir isotherm and the thermodynamic parameters Kads and ΔGadso have been also calculated and discussed. Both physisorption and chemisorption may occur on the zinc surface. Surface characterization investigation using Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) is used to ascertain the nature of the protective film. © 2015 Elsevier B.V.

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