THE INFLUENCE OF GRAIN SIZE OF PURE IRON METAL ON CORROSION INHIBITION IN PRESENCE OF SODIUM NITRITE

2012 ◽  
Vol 05 ◽  
pp. 793-800 ◽  
Author(s):  
VAHID AFSHARI ◽  
CHANGIZ DEHGHANIAN
Keyword(s):  
Grain Size ◽  
Aqueous Solutions ◽  
Corrosion Inhibition ◽  
Sodium Nitrite ◽  
Active Sites ◽  
Electrochemical Impedance ◽  
Standard Free Energy ◽  
Charge Transfer Resistance ◽  
Free Energy Of Adsorption ◽  
Transfer Resistance

The effects of grain size reduction on the corrosion inhibition of sodium nitrite were investigated using polarization curves and electrochemical impedance spectroscopy (EIS). Nanocrystalline iron (~ 45 nm) was produced by pulse electrodeposition using citric acid bath. The grain size of a nanocrystalline surface was analyzed by X-ray diffractometry (XRD) and field emission scanning electron microscopy (FESEM). The most intensive first-order peak (211) of the XRD patterns was taken for detailed analysis using a Gaussian fitting curve. The tests were carried out in 25 mg / l NaCl + 57 mg / l Na 2 SO 4 with different concentration of sodium nitrite aqueous solutions. The results revealed that due to the adsorption process which leads to the formation of a protective layer with a greater charge transfer resistance the inhibition effect and corrosion protection of sodium nitrite inhibitor in near-neutral aqueous solutions increased as the grain size decreased from microcrystalline to nanocrystalline. The standard free energy of adsorption ( ΔGads ) revealed a strong interaction between inhibitor and nanocrystalline surface. This was attributed to the increased number of the active sites caused by nanocrystalline surface.

scholarly journals Electrochemical Study on Corrosion Inhibition of Copper in Hydrochloric Acid Medium and the Rotating Ring-Disc Voltammetry for Studying the Dissolution

2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
A. K. Satpati ◽  
A. V. R. Reddy
Keyword(s):  
Hydrochloric Acid ◽  
Acid Medium ◽  
Corrosion Inhibition ◽  
Electrochemical Impedance ◽  
Electrochemical Techniques ◽  
Standard Free Energy ◽  
Charge Transfer Resistance ◽  
Standard Free Energy Change ◽  
Transfer Resistance ◽  
Hydrochloric Acid Medium

Dissolution characteristics of copper in hydrochloric acid medium and the effect of 4-amino 1,2,4-triazole (ATA) on the corrosion process have been studied using conventional electrochemical techniques and rotating ring-disc electrodes (RRDEs). Corrosion potential () and corrosion current density () were obtained by Tafel extrapolation methods. Charge transfer resistance () and double-layer capacitance () were obtained from the electrochemical impedance spectroscopy (EIS). ATA was shown to be an effective inhibitor for the copper-corrosion inhibition in acid medium. The corrosion rate was retarded in presence of inhibitors mainly because of the adsorption of the inhibitor on the electrode surface. Adsorption of the inhibitor on the metal surface was found to follow the Langmuir adsorption isotherm. Standard free energy change of the adsorption process () was calculated to be −54.3 kJ mol−1; such a large negative value of suggests the prescence of a chemisorption process.

scholarly journals Combined Experimental and Theoretical Insights into the Corrosion Inhibition Activity on Carbon Steel Iron of Phosphonic Acids

Molecules ◽  
2020 ◽  
Vol 26 (1) ◽  
pp. 135
Author(s):  
Aurelia Visa ◽  
Nicoleta Plesu ◽  
Bianca Maranescu ◽  
Gheorghe Ilia ◽  
Ana Borota ◽  
...  
Keyword(s):  
Carbon Steel ◽  
Corrosion Inhibition ◽  
Density Functional ◽  
Energy Gap ◽  
Electrochemical Impedance ◽  
Charge Transfer Resistance ◽  
Phosphonic Acids ◽  
Transfer Resistance ◽  
Potential Map ◽  
Chlorine Ions

The inhibition effect of N,N′-phosphonomethylglycine (PMG) and vinyl phosphonic acid (VPA) on the 3% NaCl acidic solution corrosion of carbon steel iron was studied at different immersion times by potentiodynamic polarization, electrochemical impedance spectroscopy, attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, and computational methods. It is found from the polarization studies that PMG and VPA behave as mixed-type inhibitors in NaCl. Values of charge transfer resistance (Rct) and double layer capacitance (Cdl) in the absence and presence of inhibitors are determined. The PMG and VPA inhibitors were capable of inhibiting the corrosion process up to ≈91% and ≈85%, respectively. In the presence of PMG, the synergic effect of chlorine ions was observed. Density functional theory (DFT) was engaged to establish the adsorption site of PMG, VPA, and their deprotonated states. For studied compounds, the resulted values of ELUMO, EHOMO, energy gap (∆E), dipole moment (μ), electronic hardness (η), global softness (σ), electrophilic index (ω), and the electronic potential map are in concordance with the experimental data results regarding their corrosion inhibition behavior and adsorption on the metal surface.

BENIGN APPROACH OF CANTHIUM PARVIFLORUM AS A BIOINHIBITOR FOR MILD STEEL CORROSION IN 0.5 M H2SO4 MEDIUM

2020 ◽  
Vol 27 (09) ◽  
pp. 1950208
Author(s):  
K. A. KARTHICK ◽  
D. S. BHUVANESHWARI ◽  
D. UMAPATHI ◽  
PANDIAN BOTHI RAJA
Keyword(s):  
Charge Transfer ◽  
Mild Steel ◽  
Electrochemical Impedance ◽  
Measurement Techniques ◽  
Charge Transfer Resistance ◽  
Effect Of Temperature ◽  
Adsorption Model ◽  
Free Energy Of Adsorption ◽  
Transfer Resistance ◽  
Vis Spectroscopy

Canthium parviflorum leaf extract (CPLE) was utilized for corrosion prevention against mild steel (MS) in 0.5[Formula: see text]mol[Formula: see text]L[Formula: see text] H2SO4 test medium. Standard corrosion measurement techniques (gravimetric and electrochemical) were employed for this purpose. Gravimetric tests clearly confirmed that the prepared CPLE efficiently performs as corrosion inhibitor. Potentiodynamic polarization measurements (PPM) and electrochemical impedance spectroscopy (EIS) measurements were performed in order to analyze the charge transfer process of CPLE. Polarization curves indicate that CPLE acts through mixed mode inhibition. Impedance study reveals that the CPLE additives enhances the charge transfer resistance values and conversely decreases values of double layer capacitance. Scanning electron microscopy (SEM), Ultraviolet-Visible (UV-Vis) spectroscopy analysis and Fourier-Transform Infrared spectroscopy (FTIR) were done to confirm the Fe-CPLE complex formation on MS. The effect of temperature reveals that the inhibition efficiency increases with decrease in temperature and increase in concentration of CPLE (maximum of 4[Formula: see text]mg[Formula: see text]L[Formula: see text]). The adsorption of CPLE shows that it obeys Langmuir’s isotherm model with free energy of adsorption, [Formula: see text][Formula: see text]kJ mol[Formula: see text]. A suitable adsorption model is also proposed.

scholarly journals Comparative Studies on the Corrosion Inhibition of Three Different Organic Heterocyclic Compounds as Corrosion Inhibitors for Mild Steel in Hydrochloric Acid

2020 ◽  
Vol 64 (4) ◽  
Author(s):  
Zineb Tribak ◽  
Mohammed Khalid Skalli ◽  
Omar Senhaji
Keyword(s):  
Hydrochloric Acid ◽  
Mild Steel ◽  
Corrosion Inhibition ◽  
Inhibition Efficiency ◽  
Charge Transfer Resistance ◽  
Protective Film ◽  
Free Energy Of Adsorption ◽  
Electron Microscopic ◽  
Transfer Resistance ◽  
Model Free

Abstract. Three organic inhibitors, based 5-Chloroisatin’s bases, namely, 1-allyl-5-chloro-indoline-2,3-dione (TZACI). 5-chloro-1-(2-(dimethylamino) ethyl) indoline-2,3-dione (TZCDI),5-chloro-1-octylindoline-2,3-dione (TZCOI) were influence on corrosion inhibition of mild steel in 1.0M hydrochloric acid solution. The inhibition efficiency increased with the increase of a compound concentration in the case of these three inhibitors, which have the mixed type behavior proposed by the polarization studies. Impedance measurements showed that after the addition of inhibitors, charge-transfer resistance increased and double-layer capacitance decreased, involving increased inhibition efficiency. The adsorption of three inhibitors on a steel surface obeyed Langmuir model. Free energy of adsorption showed that the type of adsorption was physical for TZACI and chemical for the TZCDI, TZCOI. Scanning electron microscopic analyses confirm the formation of the protective film on the surface.

Improvement of Ti/RuO2–IrO2 Anode Lifetime and Electrocatalytical Properties by Using an Eco-Friendly Thermal Decomposition Method Using Polyvinyl Alcohol as Solvent

2019 ◽  
Author(s):  
Charlys Bezerra ◽  
Géssica Santos ◽  
Marilia Pupo ◽  
Maria Gomes ◽  
Ronaldo Silva ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Polyvinyl Alcohol ◽  
High Efficiency ◽  
Electrochemical Impedance ◽  
Pechini Method ◽  
Low Cost ◽  
Charge Transfer Resistance ◽  
Transfer Resistance ◽  
Calcination Temperatures ◽  
Service Lifetime

<p>Electrochemical oxidation processes are promising solutions for wastewater treatment due to their high efficiency, easy control and versatility. Mixed metal oxides (MMO) anodes are particularly attractive due to their low cost and specific catalytic properties. Here, we propose an innovative thermal decomposition methodology using <a>polyvinyl alcohol (PVA)</a> as a solvent to prepare Ti/RuO<sub>2</sub>–IrO<sub>2</sub> anodes. Comparative anodes were prepared by conventional method employing a polymeric precursor solvent (Pechini method). The calcination temperatures studied were 300, 400 and 500 °C. The physical characterisation of all materials was performed by X-ray diffraction and scanning electron microscopy coupled with energy dispersive spectroscopy, while electrochemical characterisation was done by cyclic voltammetry, accelerated service lifetime and electrochemical impedance spectroscopy. Both RuO<sub>2</sub> and IrO<sub>2</sub> have rutile-type structures for all anodes. Rougher and more compact surfaces are formed for the anodes prepared using PVA. Amongst temperatures studied, 300 °C using PVA as solvent is the most suitable one to produce anodes with expressive increase in voltammetric charge (250%) and accelerated service lifetime (4.3 times longer) besides reducing charge-transfer resistance (8 times lower). Moreover, the electrocatalytic activity of the anodes synthesised with PVA toward the Reactive Blue 21 dye removal in chloride medium (100 % in 30 min) is higher than that prepared by Pechini method (60 min). Additionally, the removal total organic carbon point out improved mineralisation potential of PVA anodes. Finally, this study reports a novel methodology using PVA as solvent to synthesise Ti/RuO<sub>2</sub>–IrO<sub>2</sub> anodes with improved properties that can be further extended to synthesise other MMO compositions.</p>

scholarly journals Electrochemical Immunosensor for the Quantification of S100B at Clinically Relevant Levels Using a Cysteamine Modified Surface

Sensors ◽  
2021 ◽  
Vol 21 (6) ◽  
pp. 1929
Author(s):  
Alexander Rodríguez ◽  
Francisco Burgos-Flórez ◽  
José D. Posada ◽  
Eliana Cervera ◽  
Valtencir Zucolotto ◽  
...  
Keyword(s):  
Frequency Analysis ◽  
Surface Characterization ◽  
Electrochemical Impedance ◽  
Limit Of Detection ◽  
Neuronal Damage ◽  
Charge Transfer Resistance ◽  
Single Frequency ◽  
Response Analysis ◽  
Transfer Resistance ◽  
Therapeutic Decisions

Neuronal damage secondary to traumatic brain injury (TBI) is a rapidly evolving condition, which requires therapeutic decisions based on the timely identification of clinical deterioration. Changes in S100B biomarker levels are associated with TBI severity and patient outcome. The S100B quantification is often difficult since standard immunoassays are time-consuming, costly, and require extensive expertise. A zero-length cross-linking approach on a cysteamine self-assembled monolayer (SAM) was performed to immobilize anti-S100B monoclonal antibodies onto both planar (AuEs) and interdigitated (AuIDEs) gold electrodes via carbonyl-bond. Surface characterization was performed by atomic force microscopy (AFM) and specular-reflectance FTIR for each functionalization step. Biosensor response was studied using the change in charge-transfer resistance (Rct) from electrochemical impedance spectroscopy (EIS) in potassium ferrocyanide, with [S100B] ranging 10–1000 pg/mL. A single-frequency analysis for capacitances was also performed in AuIDEs. Full factorial designs were applied to assess biosensor sensitivity, specificity, and limit-of-detection (LOD). Higher Rct values were found with increased S100B concentration in both platforms. LODs were 18 pg/mL(AuES) and 6 pg/mL(AuIDEs). AuIDEs provide a simpler manufacturing protocol, with reduced fabrication time and possibly costs, simpler electrochemical response analysis, and could be used for single-frequency analysis for monitoring capacitance changes related to S100B levels.

scholarly journals Influence of HAP on the Morpho-Structural Properties and Corrosion Resistance of ZrO2-Based Composites for Biomedical Applications

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 202
Author(s):  
Réka Barabás ◽  
Carmen Ioana Fort ◽  
Graziella Liana Turdean ◽  
Liliana Bizo
Keyword(s):  
Electrochemical Impedance ◽  
Artificial Saliva ◽  
Synergetic Effect ◽  
Composite Layer ◽  
Charge Transfer Resistance ◽  
Processing Route ◽  
Dental Alloys ◽  
Metallic Electrode ◽  
Transfer Resistance ◽  
X Ray

In the present work, ZrO2-based composites were prepared by adding different amounts of antibacterial magnesium oxide and bioactive and biocompatible hydroxyapatite (HAP) to the inert zirconia. The composites were synthesized by the conventional ceramic processing route and morpho-structurally analyzed by X-ray powder diffraction (XRPD) and scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS). Two metallic dental alloys (i.e., Ni–Cr and Co–Cr) coated with a chitosan (Chit) membrane containing the prepared composites were exposed to aerated artificial saliva solutions of different pHs (i.e., 4.3, 5, 6) and the corrosion resistances were investigated by electrochemical impedance spectroscopy technique. The obtained results using the two investigated metallic dental alloys shown quasi-similar anticorrosive properties, having quasi-similar charge transfer resistance, when coated with different ZrO2-based composites. This behavior could be explained by the synergetic effect between the diffusion process through the Chit-composite layer and the roughness of the metallic electrode surface.

scholarly journals Spilanthes acmella Leaves Extract for Corrosion Inhibition in Acid Medium

Coatings ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 106
Author(s):  
Akbar Ali Samsath Begum ◽  
Raja Mohamed Abdul Vahith ◽  
Vijay Kotra ◽  
Mohammed Rafi Shaik ◽  
Abdelatty Abdelgawad ◽  
...  
Keyword(s):  
Mild Steel ◽  
Corrosion Inhibition ◽  
Active Sites ◽  
Inhibition Efficiency ◽  
Electrochemical Impedance ◽  
Film Formation ◽  
Protective Film ◽  
Surface Protection ◽  
Tafel Polarization ◽  
Spilanthes Acmella

In the present study, the corrosion inhibition effect of Spilanthes acmella aqueous leaves extract (SA-LE) on mild steel was investigated in 1.0 M HCl solution at different temperature using weight loss, Tafel polarization, linear polarization resistance (LPR), and electrochemical impedance (EIS) measurements. Adsorption of inhibitor on the surface of the mild steel obeyed both Langmuir and Temkin adsorption isotherms. The thermodynamic and kinetic parameters were also calculated to determine the mechanism of corrosion inhibition. The inhibition efficiency was found to increase with an increase in the inhibitor concentration i.e., Spilanthes acmella aqueous leaves extract, however, the inhibition efficiency decreased with an increase in the temperature. The phytochemical constituents with functional groups including electronegative hetero atoms such as N, O, and S in the extract adsorbed on the metal surface are found responsible for the effective performance of the inhibitor, which was confirmed by Fourier-transform infrared spectroscopy (FT-IR) and ultraviolet–visible spectroscopic (UV-Vis) studies. Protective film formation against corrosion was confirmed by scanning electron microscopy (SEM), atomic force microscopy (AFM), and contact angle studies. The result shows that the leaves extract acts as corrosion inhibitor and is able to promote surface protection by blocking active sites on the metal.

scholarly journals Corrosion behaviors of 316 stainless steel and Inconel 625 alloy in chloride molten salts for solar energy storage

2020 ◽  
Vol 39 (1) ◽  
pp. 340-350
Author(s):  
Mingjing Wang ◽  
Song Zeng ◽  
Huihui Zhang ◽  
Ming Zhu ◽  
Chengxin Lei ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Molten Salt ◽  
Electrochemical Impedance ◽  
Charge Transfer Resistance ◽  
Inconel 625 ◽  
Transfer Resistance ◽  
316 Stainless Steel ◽  
Corrosion Rates ◽  
Inconel 625 Alloy ◽  
Corrosion Behaviors

AbstractCorrosion behaviors of 316 stainless steel (316 ss) and Inconel 625 alloy in molten NaCl–KCl–ZnCl2 at 700°C and 900°C were investigated by immersion tests and electrochemical methods, including potentiodynamic polarization and electrochemical impedance spectroscopy. X-ray diffraction and scanning electron microscopy/energy dispersive spectroscopy were used to analyze the phases and microstructures of the corrosion products. Inconel 625 alloy and 316 ss exhibited high corrosion rates in molten chlorides, and the corrosion rates of these two alloys accelerated when the temperature increased from 700°C to 900°C. The results of the electrochemical tests showed that both alloys exhibited active corrosion in chloride molten salt, and the current density of 316 ss in chloride molten salt at 700°C was 2.756 mA/cm−2, which is about three times the value for Inconel 625 alloy; and the values of the charge transfer resistance (Rt) for Inconel 625 were larger than those for 316 ss. The corrosion of these two alloys is owing to the preferred oxidation of Cr in chloride molten salt, and the corrosion layer was mainly ZnCr2O4 which was loose and porous and showed poor adherence to metal.

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