Galvanic Interactions between Fe Electrodes in CO<sub>2 Saturated Solutions with Different pH

CORROSION ◽  
10.5006/3556 ◽  
2021 ◽  
Author(s):  
Angeire Huggins Gonzalez ◽  
Gerald Frankel ◽  
Jose Vera ◽  
William Durnie ◽  
Richard Woollam
Keyword(s):  
Photoelectron Spectroscopy ◽  
Driving Force ◽  
Open Circuit Potential ◽  
Oil And Gas Industry ◽  
Open Circuit ◽  
Bulk Solution ◽  
Co2 Corrosion ◽  
Galvanic Current ◽  
X Ray ◽  
The Difference

Localized CO2 corrosion is a very common problem in the oil and gas industry. Severe damage of the surface is attributed to the formation, and breakdown, of protective iron carbonate (FeCO3) scales. When the corrosion layer is compromised, the difference between the open circuit potential of the FeCO3-covered and non-covered regions act as the driving force for a galvanic interaction. Depending on the area ratio of the anodic and cathodic areas, the surface could suffer severe localized damage. The present study was focused on the galvanic interactions between iron samples in solutions with different pH. CO2 saturated 1% NaCl solutions with bulk pH of between 6 and 8 and temperature ranging from 20°C and 80°C were studied. A split cell allowed for customization of different environments in each of the half cells, along with simultaneous monitoring of the galvanic current and driving force as indicated by the difference in open circuit potential. Corrosion product layers were characterized using scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. The results indicated that the pH of the bulk solution plays a major role in the formation of protective FeCO3 scales. Fe exhibited passive-like behavior when immersed in a solution at 80°C with pH adjusted to 8. After reaching a passive-like behavior, Fe samples were cathodic when coupled to samples immersed in a solution with lower pH. The galvanic current decreased with increasing temperature and pH gradient.

Immobilization of Catalysts of Biological Interest on Porous Oxidized Silicon Surfaces

2008 ◽  
Vol 8 (7) ◽  
pp. 3570-3576 ◽  
Author(s):  
Wendel A. Alves ◽  
Pablo A. Fiorito ◽  
Gerard Froyer ◽  
Fady El Haber ◽  
Luc Vellutini ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Photoelectron Spectroscopy ◽  
Open Circuit Potential ◽  
Direct Electron Transfer ◽  
Open Circuit ◽  
Silicon Surfaces ◽  
Redox Mediators ◽  
X Ray ◽  
Biological Interest ◽  
Covalently Linked

The present paper deals with the immobilization of redox mediators and proteins onto protected porous silicon surfaces to obtain their direct electrochemical reactions and to retain their bioactivities. This paper shows that MP-11 and viologens are able to establish chemical bonds with 3-aminopropyltriethoxylsilane-modified porous silicon surface. The functionalization of the surfaces have been fully characterized by energy dispersive X-ray analysis (EDX) and X-ray photoelectron spectroscopy (XPS) to examine the immobilization of these mediators onto the solid surface. Amperometric and open circuit potential measurements have shown the direct electron transfer between glucose oxidase and the electrode in the presence of the viologen mediator covalently linked to the 3-aminopropyltriethoxylsilane (APTES)-modified porous silicon surfaces.

scholarly journals Χαρακτηρισμός πολυμερικών επιστρώσεων με νανοπερίεκτες σε μέταλλα για την προστασία τους από διάβρωση σε θαλάσσιο περιβάλλον

2012 ◽  
Author(s):  
Ανδρόνικος Μπαλάσκας
Keyword(s):  
Electrochemical Impedance Spectroscopy ◽  
Open Circuit Potential ◽  
Electrochemical Impedance ◽  
Open Circuit ◽  
X Ray Diffraction ◽  
X Ray ◽  
Organically Modified Silicates ◽  
Organically Modified ◽  
Ft Ir ◽  
Scanningelectron Microscopy

Υβριδικές επιστρώσεις οργανικά τροποποιημένων πυριτικών ενώσεων και εποξειδικώνρητινών (Organically Modified Silicates, ORMOSILs – epoxy) εφαρμόστηκαν στο κράμααργιλίου 2024-Τ3 και σε γαλβανισμένο χάλυβα σε υψηλές θερμοκρασίες (Hot Dip GalvanizedSteel, HDGS) προκειμένου αυτές να προστατεύσουν τα υποστρώματα από τη διάβρωση. Για τηνβελτίωση της αντοχής των επιστρώσεων στην διάβρωση ενσωματώθηκαν στην πολυμερικήμήτρα νανοπεριέκτες από μολυβδαινικό δημήτριο (CeMo) και οξείδιο του τιτανίου (TiO2),καθώς και pH-ευαίσθητα οργανικά νανοδοχεία πληρωμένα με τους αναστολείς διάβρωσης 2-μερκαπτοβενζοθειαζόλιο, 8-υδροξυκινολίνη, 1H-βενζοτριαζολο-4-σουλφονικό οξύ καιεξαφλουοροτιτανικό οξύ.Οι υβριδικές επιστρώσεις εφαρμόστηκαν στο υπόστρωμα με τη διαδικασία εμβάπτισης.Η μορφολογία των επιστρώσεων εξετάστηκε με ηλεκτρονική μικροσκοπία σάρωσης (ScanningElectron Microscopy (SEM)). Η σύνθεση και η δομή τους μελετήθηκε με υπέρυθρηΦασματοσκοπία μετασχηματισμού Fourier (FT-IR) και με μικροανάλυση με φθορισμομετρίαακτίνων Χ (Energy Dispersive X-Ray Analysis (EDX)). H ηλεκτροχημική φασματοσκοπίασύνθετης αντίστασης (Electrochemical Impedance Spectroscopy, EIS), η dc-πόλωση (dcpolarization)και η μέτριση ανοικτού δυναμικού (open circuit potential, OCP) χρησιμοποιήθηκανγια την αξιολόγηση των αντι-διαβρωτικών ιδιοτήτων των επιστρώσεων. Τα αποτελέσματαέδειξαν ότι οι επιστρώσεις με πληρωμένα νανοδοχεία έχουν αυξημένες αντιδιαβρωτικέςιδιότητες συγκριτικά με τις υπόλοιπες επιστρώσεις εμφανίζοντας και ιδιότητες αυτο-θεραπείας.Τέλος, συντέθηκαν νανόσφαιρες οξειδίου του χαλκού (Cu2O), οι οποίεςχαρακτηρίστηκαν με SEM, ηλεκτρονική μικροσκοπία διερχόμενης δέσμης (ΤransmissionΕlectron Μicroscopy (TEM)) και περίθλαση ακτίνων Χ (X ray Diffraction (XRD)). Οινανόσφαιρες στη συνέχεια πληρώθηκαν με ουσίες που δρουν ως βιοκτόνα και ενσωματώθηκανσε βαφές εμπορίου και σε επιστρώσεις βασισμένες σε εποξειδικές ενώσεις και μελετήθηκε ηδράση τους ως αντιαποθετικά αντιδραστήρια. Τα αποτελέσματα έδειξαν ότι οι επιστρώσεις μεπληρωμένες νανόσφαιρες Cu2O είχαν μεγαλύτερη αποτελεσματικότητα σε σύγκριση με τιςβαφές εμπορίου με βιοκτόνα μετά από έκθεση σε θαλάσσιο περιβάλλον.

Photovoltaic properties of silicon nanocrystals in silicon nitride prepared by ammonia sputtering

2015 ◽  
Vol 08 (05) ◽  
pp. 1550052
Author(s):  
Xiaobo Chen
Keyword(s):  
Silicon Nitride ◽  
Flow Rate ◽  
Photoelectron Spectroscopy ◽  
Silicon Nanocrystals ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Open Circuit ◽  
Photovoltaic Properties ◽  
X Ray ◽  
Xps Characterization

In this work, we present an investigation of the photovoltaic properties of low-temperature (700°C annealing temperature) prepared P -doped Silicon nanocrystals ( Si   NCs ) in silicon nitride by ammonia sputtering followed by rapid thermal annealing (RTA). We examined how the flow rate of NH3influenced the structural properties of the annealed films by using Raman scattering, grazing incidence X-ray diffraction (GI XRD) and transmission electron microscopy (TEM), it was found that the appropriate flow rate of NH3is 3 sccm. For the sample deposited at the flow rate of 3 sccm, TEM image showed that Si   NCs were formed with a mean size about 3.7 nm and the density of ~ 2.1 × 1012cm-2; X-ray photoelectron spectroscopy (XPS) characterization showed the existence of Si – P bonds, indicating effective P doping; the average absorptance of higher than 65% and a significant amount of photocurrent makes it suitable for photoactive. Moreover, the experimental P -doped Si   NCs : Si3N4/ p - Si heterojunction solar cell has been fabricated, and the device performance was studied. The photovoltaic device fabricated exhibits an open-circuit voltage (VOC) and a short-circuit current density (JSC) of 470 mV and 3.25 mA/cm2, respectively.

Efficient visible-light photocatalytic degradation of sulfadiazine sodium with hierarchical Bi7O9I3 under solar irradiation

2015 ◽  
Vol 72 (12) ◽  
pp. 2122-2131 ◽  
Author(s):  
MengMeng Xu ◽  
YaLei Zhao ◽  
QiShe Yan
Keyword(s):  
Visible Light ◽  
Photoelectron Spectroscopy ◽  
Oxygen Demand ◽  
Solar Irradiation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Optical Test ◽  
Different Seasons ◽  
Uv Visible ◽  
The Difference

Bi7O9I3, a kind of visible-light-responsive photocatalyst, with hierarchical micro/nano-architecture was successfully synthesized by oil-bath heating method, with ethylene glycol as solvent, and applied to degrade sulfonamide antibiotics. The as-prepared product was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-visible diffuse reflection spectra and scanning electron microscopy (SEM). XRD and XPS tests confirmed that the product was indeed Bi7O9I3. The result of SEM observation shows that the as-synthesized Bi7O9I3 consists of a large number of micro-sheets with parallel rectangle structure. The optical test exhibited strong photoabsorption in visible light irradiation, with 617 nm of absorption edges. Moreover, the difference in the photocatalytic efficiency of as-prepared Bi7O9I3 at different seasons of a whole year was investigated in this study. The chemical oxygen demand removal efficiency and concentration of NO3− and SO42– of solution after reaction were also researched to confirm whether degradation of the pollutant was complete; the results indicated a high mineralization capacity of Bi7O9I3. The as-synthesized Bi7O9I3 exhibits an excellent oxidizing capacity of sulfadiazine sodium and favorable stability during the photocatalytic reaction.

Aluminium corrosion studies. IV. Pitting corrosion

1978 ◽  
Vol 31 (5) ◽  
pp. 943 ◽  
Author(s):  
RT Lowson
Keyword(s):  
Open Circuit Potential ◽  
Chloride Concentration ◽  
Open Circuit ◽  
Aluminium Chloride ◽  
Bulk Solution ◽  
Pitting Potential ◽  
Functional Relationships ◽  
Corrosion Studies ◽  
Thermodynamic Equilibrium Condition ◽  
Chloride Activity

Measurements are reported for the variation of the open-circuit potential, Er, of aluminium in oxygen-saturated sodium salt solutions. The value of Er was independent of SO42- and NO3- concentrations and similar to the value obtained for water (0.04 (s.h.e.)). Er was a function of chloride concentration given by ������������������� Er = -0.475-0.060log[Cl-] V (s.h.e.) at 25�C. There was a less well defined relationship between Er and NO2-, I- and Br-, and a complex relationship with F-. ��� The potentiodynamic characteristics are reported for aluminium in 1-0.01 mol l-1 Cl- oxygen-saturated solutions. Functional relationships were found for E0, Ep, Es and E0' with chloride activity at 5, 25, 50 and 75°C. Hysteresis effects are reported. ��� The experimental results are interpreted in terms of a thermodynamic equilibrium condition between the surface oxide and soluble aluminium chloride. As the system oscillates across the equilibrium conditions the surface will passivate or pit. A critical bulk solution chloride concentration is necessary to maintain the growth of the pit; the experimental value was 1.6 mol l-1 Cl- and the corresponding open-circuit potential was Ecrit = -0.48 V (s.h.e.). The pitting potential, Ev, was interpreted as an overpotential, ηp, given by η = Ep,- Ep-Ecrit.

Corrosion Behavior of Surfaced AM50 Magnesium Alloys under Stress Conditions

2010 ◽  
Vol 95 ◽  
pp. 79-83
Author(s):  
Amir Eliezer
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloys ◽  
Open Circuit Potential ◽  
Electrochemical Impedance ◽  
Spinel Phase ◽  
Ceramic Coatings ◽  
Open Circuit ◽  
Stress Conditions ◽  
X Ray Diffraction ◽  
X Ray

Micro-arc oxidization of AM50 magnesium alloys was studied. The influence of micro-arc oxidization process was investigated; phase structure were analyzed using X-ray diffraction (XRD). Open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) were used to evaluate the corrosion resistance of ceramic coatings formed on magnesium alloys under stress conditions. XRD analyses indicate that the ceramic coatings fabricated on the surface of magnesium alloys by micro-arc oxidization are composed of spinel phase MgAl2O4 The corrosion resistance of ceramic coatings is improved compared with magnesium alloy substrate.

scholarly journals Adsorption of Strontium onto Synthetic Iron(III) Oxide up to High Ionic Strength Systems

Minerals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1093
Author(s):  
David García ◽  
Johannes Lützenkirchen ◽  
Maximilien Huguenel ◽  
Léa Calmels ◽  
Vladimir Petrov ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Surface Complexation ◽  
Pitzer Model ◽  
Bulk Solution ◽  
Iron Corrosion ◽  
Acid Base ◽  
Model Framework ◽  
Surface Complexes ◽  
X Ray ◽  
Aqueous Species

In this work, the adsorption behavior of Sr onto a synthetic iron(III) oxide (hematite with traces of goethite) has been studied. This solid, which might be considered a representative of Fe3+ solid phases (iron corrosion products), was characterized by X-Ray Diffraction (XRD) and X-Ray Photoelectron Spectroscopy (XPS), and its specific surface area was determined. Both XRD and XPS data are consistent with a mixed solid containing more than 90% hematite and 10% goethite. The solid was further characterized by fast acid-base titrations at different NaCl concentrations (from 0.1 to 5 M). Subsequently, for each background NaCl concentration used for the acid-base titrations, Sr-uptake experiments were carried out involving two different levels of Sr concentration (1·10−5 and 5·10−5 M, respectively) at constant solid concentration (7.3 g/L) as a function of −log([H+]/M). A Surface Complexation Model (SCM) was fitted to the experimental data, following a coupled Pitzer/surface complexation approach. The Pitzer model was applied to aqueous species. A Basic Stern Model was used for interfacial electrostatics of the system, which includes ion-specific effects via ion-specific pair-formation constants, whereas the Pitzer-approach involves ion-interaction parameters that enter the model through activity coefficients for aqueous species. A simple 1-pK model was applied (generic surface species, denoted as >XOH−1/2). Parameter fitting was carried out using the general parameter estimation software UCODE, coupled to a modified version of FITEQL2. The combined approach describes the full set of data reasonably well and involves two Sr-surface complexes, one of them including chloride. Monodentate and bidentate models were tested and were found to perform equally well. The SCM is particularly able to account for the incomplete uptake of Sr at higher salt levels, supporting the idea that adsorption models conventionally used in salt concentrations below 1 M are applicable to high salt concentrations if the correct activity corrections for the aqueous species are applied. This generates a self-consistent model framework involving a practical approach for semi-mechanistic SCMs. The model framework of coupling conventional electrostatic double layer models for the surface with a Pitzer approach for the bulk solution earlier tested with strongly adsorbing solutes is here shown to be successful for more weakly adsorbing solutes.

scholarly journals Corrosion behavior of GeO2 and Sc2O3 Coatings on AZ31 Alloy

2021 ◽  
Vol 37 (2) ◽  
pp. 433-439
Author(s):  
L. Sutha ◽  
A. Cyril
Keyword(s):  
Open Circuit Potential ◽  
Corrosion Current ◽  
Az31 Alloy ◽  
Germanium Dioxide ◽  
Electrode System ◽  
Open Circuit ◽  
X Ray ◽  
X Ray Crystallography ◽  
Corrosion Studies ◽  
Surface Examination

In this work, GeO2 (germanium dioxide) and Sc2O3 (scandium trioxide) were developed as coatings on AZ31 alloy using polymer binder. The coatings were characterized using X-ray crystallography procedure (XRD), infrared spectrum of absorption or emission of a solid procedure (FTIR), Raman spectroscopy procedure, surface examination by FESEM. The corrosion studies were analyzed using a three electrode system in 3.5% NaCl electrolyte. The bare AZ31 alloy showed open circuit potential (Ecorr) of -1.7 V (SCE) and the corrosion current density (icorr) of 3.4 x 10-4 mA/cm2, while the Sc2O3 coated AZ31 alloy exhibited Ecorr of -1.4 V (SCE) and the icorr of 5.4 x 10-9 mA/cm2 and while the GeO2 coated AZ31 alloy exhibited Ecorr of -1.3 V (SCE) and the icorr of 2.59 x 10-9 mA/cm2. The results reveal that the GeO2 coated AZ31 alloy demonstrated higher corrosion resistance than of bare AZ31 alloy and Sc2O3 coated AZ31 alloy.

scholarly journals Self-Regeneration Effect of Three-Way Catalysts during Thermal Aging Procedure

Catalysts ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1257
Author(s):  
Evgeny A. Alikin ◽  
Sergey P. Denisov ◽  
Konstantin V. Bubnov ◽  
Aleksey A. Vedyagin
Keyword(s):  
Photoelectron Spectroscopy ◽  
Nox Reduction ◽  
Catalytic Performance ◽  
Phase Changes ◽  
X Ray ◽  
Long Term Stability ◽  
Short Period ◽  
The Difference ◽  
Regeneration Effect ◽  
Model Engine

One of the most important features of the three-way catalysts is their long-term stability. However, quite often, promising catalytic compositions with excellent activity become deactivated after a relatively short period of exploitation due to various reasons. Therefore, a study on the onboard regeneration of the deactivated three-way catalysts remains its actuality. The present work is mainly focused on the self-regeneration effect of the rhodium-containing component. Aging of the catalysts in the standard and model engine braking regimes revealed the difference in the catalytic performance. Deactivated rhodium species turned to the active state as a result of rapid cooling in air flow from 1200 to 600 °C. The regenerated catalyst shows improved activity towards NOx reduction and, therefore, widened operation window, which indicates higher accessibility of the rhodium species. X-ray diffraction analysis of the aged catalysts does not reveal any noticeable phase changes. Contrary, significant changes in the Rh oxidation state were registered by X-ray photoelectron spectroscopy. The observed effect opens new horizons for the development of the onboard purification systems with prolonged exploitation lifetime.

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