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Oxygen reduction on Cu in near-neutral 5% NaCl and its subsequent inhibition by Cr(VI) and Ce(III) compounds has been examined using stationary and rotating Cu electrodes. The results show that Cr(VI) is a highly efficient inhibitor not matched by comparable concentrations of Ce(III) in its effect. Results suggest (i) bulk reduction of Cr(VI) to a...
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Context 1
... cations appear to have no inhibiting influence in the -0.6 V to -0.8 V region where Cr(VI) lowers reduction currents. Figure 2 shows the diffusion limited currents obtained for a Cu RDE biased at -0.7 V as a function of the reciprocal diffusion layer thickness, δ -1 , where δ = 1.75ω -1/2 ν -1/6 D. 1/2 The current depends on the hydrodynamically defined diffusion length in the absence of any inhibitor. Addition of 0.01 M Cr(VI) virtually eliminates rotation rate dependence and lowers the current. ...
Context 2
... of 0.01 M Cr(VI) virtually eliminates rotation rate dependence and lowers the current. A 100-fold difference between the Cr(VI) inhibited and inhibitor free currents requires as determined by extrapolation (Figure 2) a δ of 2.6 µm, a scale typical for the cathodes on Al 2024 T3 in 5% NaCl. ...
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Citations
... If there is a difference in corrosion potential (E corr ) values between the presence and absence of synthetic molecules of more than 85 mV, the inhibitor molecules are classified as cathodic or anodic, but this did not happen since the displacement in corrosion potential values is less than 85 mV. However, a little change in the E corr (63 mV) and a small change in (ß a & ß c ) on the rise in the dose of the used inhibitors revealed that these compounds work as mixed type inhibitors 60,61 . The corrosion current density www.nature.com/scientificreports/ ...
Two 3D-supramolecular coordination polymers (SCP1 & SCP2) have been synthesized and characterized by physicochemical and spectroscopic methods. In a solution of 1.0 M HCl, SCPs were used to prevent corrosion of carbon steel (CS). The inhibition productivity (%η) rises as the synthetic inhibitor dose rises, and the opposite is true as the temperature rises. The study was carried out using chemical (mass loss, ML) and electrochemical ( potentiodynamic polarization, PDP and electrochemical impedance microscopy, EIS) techniques, which showed %η reached to 93.1% and 92.5% for SCP1 & SCP2, respectively at 21 × 10⁻⁶ M, 25 °C. For the polarization results, SCPs behave as mixed-type inhibitors. With increasing doses of SCPs, the charge transfer resistance grew and the double layer's capacitance lowered. The creation of a monolayer on the surface of CS was demonstrated by the finding that the adsorption of SCPs on its surface followed the Henry adsorption isotherm. The parameters of thermodynamics were computed and explained. The physical adsorption of SCPs on the surface of CS is shown by the lowering values of free energy (∆Goads < − 20 kJ mol⁻¹) and increasing the activation energy (E*a) values in presence of SCP1 & SCP2 than in their absence. Atomic force microscope (AFM) and scanning electron microscopy (SEM) demonstrated the development of a protective thin film of SCPs precipitated on the surface of CS. There is a strong matching between results obtained from experimental and theoretical studies. Results from each approach that was used were consistent.
... this section, SECM experiments were designed to confirm the presence of Cu particles deposits on post-exposed samples and prove that these deposits can act as local cathodes (i.e., catalytic areas) to reduce oxygen (ORR). 28,29 The SECM experiments were carried out in the Cl electrolyte. The SECM competition mode was used to seek areas with high ORR activity as local cathodes. ...
The corrosion mechanism of microporous nickel-chromium multilayer coatings was studied at localised scale by Scanning Electrochemical Microscopy (SECM) after exposure to an aggressive electrolyte (chloride-based one at pH 3.1 containing cupric ions). The open circuit potential was initially monitored during 22 h, followed by a detailed characterisation using Glow Discharge-Optical Emission Spectroscopy and Field Emission Scanning Electron Microscope. Interestingly, Cu deposition occurs over the surface of the microporous nickel layer, and it is located on spots where micro-discontinuities (i.e., cracks and pores) of the outermost Cr layer are present. The application of different operation modes of the SECM (i.e., redox competition and surface generation/tip collection) not only reveals such copper deposits (which were identified after monitoring their catalytic capabilities for oxygen reduction reaction) but also confirms the stepwise reduction of Cu ²⁺ to Cu ⁰ (via intermediate species of Cu ⁺ ) during the corrosion process. The impact of metallic copper particles in the local pH due to their catalytic activity could also explain why the microporous nickel layer is not corroded after exposure to such electrolyte.
... U zavisnosti od operativnh uslova (brzine grijanja i vremena boravka) piroliza mikroalgi se dijeli na sporu (najčešće 10˚C/min) i brzu pirolizu (najčešće više od 100˚C/s) [43]. Bioulje dobijeno brzom pirolizom ima manju viskoznost i veću toplotnu moć od mikroalgalnog biogoriva dobijenog sporom pirolizom [44]. ...
... Copper has a powerful ability to neutralize infectious viruses such as bronchitis virus, poliovirus, human immunodeficiency virus (HIV-1), norovirus and other unilateral or bilateral DNA and RNA viruses [44]. One of the causes of high speed A. Mitovski et al. ...
... If the change in corrosion potential (E corr ) values is greater than 85 mV in the presence and absence of synthetic molecule, the inhibitor molecules are classified as cathodic or anodic type, and this did not happen because the corrosion potential values displacement less than 85 mV. The corrosion current density diminished with increasing the doses of the synthetic compounds but the small change of the E corr (63 mV) and the slightly change of ( a & c ) on rising the doses of the utilized inhibitors, this revealed that these compounds act as mixed type inhibitors [44,45]. The (η Tafel %) was calculated from PP curves as follows: 3.6.2. ...
SADRŽAJ – CONTENT
Milica Preradović, Saša Papuga
Third generation biofuels – cultivation methods and technologies for processing of microalgal biofuels ........................................................................ 249
Mihailo Mrdak, Časlav Lačnjevac, Marko Rakin, Đorđe Janaćković, Darko Veljić, Darko Bajić
Characterisation of biocompatible layers of ZrO28%Y2O used in combination with other ceramics to modify the surface of implants ............. 262
Slobodan Cvetković, Mirjana Kijevčanin
Balancing of energy flows in a life cycle of thermal energy production from biogas ................... 269
Josephath Jeyabal Maria Praveena, Jeyaraj Angelin Clara, Susai Santhammal Rajendran, Antony John Amalraj
Inhibition of corrosion of mild steel in well water by an aqueous extract of soapnut (Sapindus Trifoliatus) ................................................................... 277
Slađana Tanasković, Mirjana Antonijević-Nikolić, Branka Dražić
Thermal behavior and biological activity of [Co2(Cl)2 tpmc](BF4)2 complex ................................... 291
Aleksandra Mitovski, Vesna Grekulović, Nada Štrbac, Sanja Milutinović Jovanović, Kristina Božinović, Milica Zdravković
Antimicrobial properties of copper and its alloys through the prism of the current SARS CoV-2 pandemic ..................................................................... 297 Victor David Arockiaraj Mallika Jeslina, Suyambulingam Jone Kirubavathy, Abdulhameed Al-Hashem, Susai Santhammal Rajendran RM Joany, Caslav Lacnjevac
Inhibition of corrosion of mild steel by an alcoholic extract of a seaweed Sargassum muticum ....................................................................... 304
Abd El-Aziz S. Fouda, Safaa Eldin H. Etaiw, Essam El-Waseef
Synthesis of two supramolecular coordination polymers and electrochemical evaluation of their corrosion inhibition performance on corrosion of Carbon Steel in Acidic medium ................................. 316
Imo Ejeagba Okorie, Nwokorie Romanus Chukwudi
A review of fungal influenced corrosion of metals . 333
Leonid Dvorkin, Lyudmila Nihaeva
Modified supersulfated cements ............................... 340 Manuscript preparation - Uputstvo za pripremu rada..... 349
Advertisements - Reklame ................................................ 353
... If the change in corrosion potential (E corr ) values is greater than 85 mV in the presence and absence of synthetic molecule, the inhibitor molecules are classified as cathodic or anodic type, and this did not happen because the corrosion potential values displacement less than 85 mV. The corrosion current density diminished with increasing the doses of the synthetic compounds but the small change of the E corr (63 mV) and the slightly change of ( a & c ) on rising the doses of the utilized inhibitors, this revealed that these compounds act as mixed type inhibitors [44,45]. The (η Tafel %) was calculated from PP curves as follows: 3.6.2. ...
The effect of the SCPs-[CuII(en)2] [CuI (CN)2]2. H2O] (SCP1) and {[H2DAB] [Cu4(CN)6].2H2O} (SCP2) as corrosion inhibitors for carbon steel (CS) was studied in 1.0M HCl solution. As the synthesized inhibitor dose increases, the inhibition productivity (%e) increases reaching to 90.3% and 89.9% at 21x10-6M dose for SCP2 and SCP1, respectively. This result evidenced by mass loss (ML) investigated at three different temperatures 25-35-45oC, while potentiodynamic polarization (PP), electrochemical impedance spectroscopy (EIS), and electrochemical frequency modulation technique (EFM) were tested at 25°C. The synthesized inhibitors adsorbed on the CS surface physically allowing Henry isotherm. The results displayed that the synthesized inhibitors are excellent and their (%e) was significantly increased by raising the dose and decreased by raising the temperature. Polarization curves revealed that the synthesized inhibitors act as mixed type. The thermodynamic parameters were calculated and discussed. The protection was confirmed by the creation of the thin film of inhibitors precipitated on the surface of CS.
... The potential of corrosion, E corr has no shift; therefore, the organic derivatives may be assumed as mixed-type inhibitors. The corrosion inhibition efficiency was calculated according to following equation [22]: IE Tafel % = [(I°c orr -I corr ) / I°c orr ] × 100 Where, I corr and I 0 corr represent inhibited and uninhibited corrosion current, respectively. ...
In this study, the electro-chemical behavior of Udimet700 alloys is studied in acidic media at 25°C. It deals with the corrosion inhibition process of nickel-based (Udimet700) alloy in 1M-HCl solution by some organic derivatives. The methods used include electro-chemical frequency modulation technique, electro-chemical impedance spectroscopy, and potentio-dynamic polarization. The derivatives are considered as mixed-type inhibitor depending on potentio-dynamic polarization analysis. Scanning electron microscope examination is executed to study the morphology of Udimet700 surface after immersion in a solution in the case of presence and absence of derivatives. The results of this research reveal that the inhibitors are absorbed by Udimet700 alloy surface and they insulate it from the acidic medium. The compound (C 16 H 17) among the tested organic derivatives plays the best role as an inhibitor of the alloy in 1M-HCl.
... The corrosion inhibition efficiency might have been computed as shown [36] in equation (1): ...
Corrosion behavior of composite Udimet 700 with (5%& 10%) alumina powder superalloys was studied in 1 M
HCl using some new organic compounds “4-((4-aminophenyl) diazenyl) benzene-1,2-disulfonic acid (compound
I), N-(benzo[d] thiazol-2-yl) -2-cyanoacetamide (compound II) and ethyl (E)-2-cyano-2- (2-(1,5-dimethyl-3-oxo-
2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)hydrazono) acetate (compound III)”. Electrochemical studies were carried
out, utilizing potentiodynamic polarization, electrochemical impedance spectroscopic and electrochemical frequency
modulation methods. Tafel plots demonstrate that the presence of organic compounds lightly affects the
general shape of the polarization bends at 25 �C and acts as a mixed-type inhibitor. The adsorption isotherm
model of these compounds on Udimet 700 surface followed Langmuir adsorption isotherm in 1 M HCl solution.
The Nyquist plots yield good semicircles, whose radius of curvature increases with expanding the concentration
of the tried inhibitors. EFM demonstrated that, the non– straight reaction includes sufficient data about the
corroding cycle so that, the current of corrosion can be computed straightforwardly. SEM studies reveal that, the
surface morphology shows a marked change in the surface properties after using the organic derivatives.
Theoretically by quantum chemical calculations using DFT method fit with theoretical methods.
... A specific interaction between some functional groups, which contain atoms such as nitrogen, oxygen and sulfur, due to their free and alone electron pairs, and metal surface is the main action of these inhibitors. Recently, there has been a big interest among scientific community the interest on the naturally occurring inhibitors extracted from leaves, roots and fruits because of the existence of this type of atoms contained in organic compounds [14][15][16] with conjugated double bonds and polar functional groups [17][18][19][20] that has been proved to efficiently inhibit copper corrosion. Some plants had been studied as corrosion inhibitors such as Salvia officinalis [21], Musa paradisica [22], Capsicum annuum [23], Adhotada vasica [24], among others. ...
The effect of plasma pre-oxidation on the effect of the inhibition performance of N-[2-[(2-hydroxyethyl) amino] ethyl]-amide extracted from coffee bagasse for Cu in 3.5% NaCl has been investigated by using electrochemical techniques. Electrochemical impedance spectroscopy, potentiodynamic polarization curves and linear polarization resistance (LPR) measurements were the employed techniques. Results have shown that the corrosion rate of Cu was decreased and the properties of the passive film formed by the inhibitor were improved. Corrosion protection given by the inhibitor and pre-oxidizing treatment improves as time elapses due to an increase of the surface area covered by the corrosion products layer. This has been explained in terms of a better adherence of the inhibitor-formed film to the metal which by pre-oxidizing.
... Corrosion inhibitors are substances which, when added in a small concentration to a corrosive media, decrease or prevent the reaction of metal with the media [13]. Most of the wellknown corrosion inhibitors are organic compounds [14][15][16][17][18][19][20]. Organic compounds containing functional groups with heteroatom such as oxygen, nitrogen and sulphur are capable of donating valence electrons. ...
The inhibition effect of potassium gluconate on the corrosion behaviour of mild steel in 0.5 M HCl at ambient temperature has been examined by open circuit potential and potentiodynamic polarization measurements. Morphology of the mild steel specimens was studied using scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectrometer (EDS) before and after corrosion tests. The corrosion rate decreased with an increase in inhibitor concentration. The inhibition efficiency increased with increasing concentration of inhibitors. Results show that potassium gluconate is a mixed type inhibitor; the adsorption of the inhibitor on the mild steel surface is in agreement with Frumkin, Langmuir, and Freundlich adsorption isotherm. The grey relational model used corresponds with the experimental results.
... The use of organic inhibitors containing polar groups including nitrogen, sulphur and oxygen [11][12][13][14][15][16] is one of the most important methods in the protection of copper against corrosion. It has been reported that heterocyclic compounds with polar functional groups and conjugated double bonds [17][18][19][20] can be used to inhibit copper corrosion. ...
A palm-oil modified hydroxyethyl imidazoline has been used as corrosion inhibitor for Cu in 3.5 % NaCl solution by using potectiodynamic polarization curves, linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS) measurements. Results showed that modified imidazoline acts as good inhibitor for Cu and its efficiency increases with increasing its concentration and exposure time. It was found that modified imidazoline contains compounds with heteroatoms within their molecular structure which act as sites to be chemically adsorbed on to the Cu surface, by following a Langmuir type of isotherm, to form protective corrosion products
... Copper and its alloys are widely used in industrial and atmospheric applications, electric wires, electronic building construction, etc., due to their excellent properties like thermal and electric conductivity, low cost and abundancy [1][2][3][4][5]. However, it is not immune to corrosion attack. ...
... Organic inhibitors are one of the most used methods in order to prevent and control corrosion. The main action of these inhibitors is a specific interaction between some functional groups and metal surface through heteroatoms such as nitrogen, oxygen and sulfur, which play a crucial role due to their free and alone electron pairs [5][6][7][8]. For instance, Tavakoli et al. [9] inhibition effects of sodium dodecylbenzenesulphonate (SDBS) and 2-mercaptobenzoxazole (2-MBO) on corrosion of copper in sulphuric acid solution have been studied using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization curves. ...
... I.E.100 (Rp1 -Rp2)/ Rp1 (5) where Rp1 is the polarization resistance with inhibitor and Rp2 the polarization resistance without inhibitor and the change in the I.E. value with time at the different inhibitor concentrations in Fig. 4. It can be seen that efficiency values rapidly increases, reaching a steady state value in less than 5 hours of exposure to the electrolyte. ...
The inhibition effect of a palm-oil modified hydroxyethyl imidazoline on the corrosion of copper in 1.0 M sulphuric acid (H2SO4) has been studied by using potentiodynamic polarization curves, linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS) measurements. Modified imidazoline resulted a good corrosion inhibitor for Cu in acid environment, with its inhibition efficiency increasing with its concentration, reaching its highest value when 10 ppm are added, but it decreased with a further increase in its concentration. Additionally, inhibitor efficiency increased with an increase in the immersion time. Polarization curves showed that modified imidazoline suppresses in a greater extent the cathodic oxygen reduction reaction than the anodic dissolution, acting, therefore, as a mixed type of inhibitor. EIS data indicated the decrease in the double layer capacitance and an increase in the charge transfer resistance due to the adsorption of the modified imidazoline on to the copper surface, with the formation of protective corrosion products.
