scholarly journals Molar Ratio Effect of Sodium to Chloride Ions on the Electrochemical Corrosion of Alloy 600 and SA508 in HCl + NaOH Mixtures

Materials ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1970
Author(s):  
Do Haeng Hur ◽  
Jeoh Han ◽  
Jun Choi
Keyword(s):  
Electrochemical Corrosion ◽  
Chloride Ion ◽  
Chloride Ions ◽  
Molar Ratio ◽  
Alloy 600 ◽  
Galvanic Coupling ◽  
Ratio Effect ◽  
Molar Ratios ◽  
Corrosion Rates ◽  
A Value

This study aims to investigate the molar ratio effect of sodium to chloride ions on the corrosion of an Alloy 600 steam generator tube and an SA508 tubesheet material. The corrosion behavior was evaluated in solutions with three different molar ratios of sodium to chloride ions using a potentiodynamic polarization method. The corrosion potentials and corrosion rates of both the two materials were significantly decreased as the molar ratio increased from 0.1 to 10. Therefore, it is recommended that the molar ratio control to a value of 1 is beneficial only when the crevice chemistry has a low molar ratio with an acidic pH. The corrosion potentials and corrosion rates were little affected by the total sodium and chloride ion concentrations. SA508 acted as an anode and its corrosion rate was accelerated by galvanic coupling with Alloy 600.

Effect of the Grain Size on Electrochemical Corrosion Behavior of Cu60Ni20Cr20 Alloys in Solutions Containing Chloride Ions

2012 ◽  
Vol 476-478 ◽  
pp. 16-20
Author(s):  
Guo De Li ◽  
Jing Bian ◽  
Zhong Qiu Cao ◽  
Ke Zhang ◽  
Ya Jun Fu
Keyword(s):  
Grain Size ◽  
Corrosion Behavior ◽  
Electrochemical Corrosion ◽  
Chloride Ion ◽  
Chloride Ions ◽  
Coarse Grained ◽  
Protective Film ◽  
Ion Concentrations ◽  
Corrosion Rates ◽  
Electrochemical Corrosion Behavior

The two Cu60Ni20Cr20alloys with the different grain size were prepared by conventional casting (CA) and mechanical alloying (MA) through hot pressing. Effect of the grain size on electrochemical corrosion behavior of the two Cu60Ni20Cr20 alloys was also studied in solutions containing chloride ions. Results show that the free corrosion potentials of the two alloys move toward to negative values, corrosion current densities increase and therefore corrosion rates become faster with the increment of chloride ion concentrations. CACu60Ni20Cr20alloy and MACu60Ni20Cr20alloy have passive phenomena in 0.05mol/L Na2SO4 neutral solution, but passive phenomena become weak or disappear when the chloride ions are added. Corrosion rates of the nanocrystalline MACu60Ni20Cr20alloy become slower than those of the coarse grained CACu60Ni20Cr20alloy in solutions containing the same chloride ion concentrations because MACu60Ni20Cr20alloy is able to produce large concentrations of grain boundaries and passive elements is able to diffuse quickly to form the protective film.

Electrochemical Corrosion Behavior of Cu-20Fe-12Cr Alloys with the Different Grain Size in Solutions Containing Chloride Ions

2011 ◽  
Vol 399-401 ◽  
pp. 655-661
Author(s):  
Zhong Qiu Cao ◽  
Rong Xue ◽  
Jing Bian ◽  
Ya Jun Fu
Keyword(s):  
Grain Size ◽  
Corrosion Behavior ◽  
Electrochemical Impedance ◽  
Electrochemical Corrosion ◽  
Chloride Ion ◽  
Chloride Ions ◽  
Ion Concentrations ◽  
Corrosion Rates ◽  
Electrochemical Corrosion Behavior ◽  
Different Grain Size

Electrochemical corrosion behavior of Cu-20Fe-12Cr alloys prepared by powder metallurgy (PM) and mechanical alloy (MA) with the different grain size was studied in solutions containing chloride ions. The free corrosion potentials move toward negative values and corrosion rates become faster with the increase of chloride ion concentrations for two alloys. Electrochemical impedance spectroscopy (EIS) plots of PMCu-20Fe-12Cr alloy are composed of a capacitive loop and a diffusion tail. Corrosion processes are controlled by diffusion. EIS plots of MACu-20Fe-12Cr alloy in Na2SO4 or 0.02mol.L-1NaCl solution are unable to have characteristics of Warburg impedance. Corrosion processes are controlled by electrochemical reactions. After chloride ion concentrations increase up to 0.05mol.L-1, their EIS plots are composed of double capacitive loops with a straight line induced Warburg resistance between two capacitive loops. The above EIS plots imply the existence of pitting corrosion. The corrosion rates of MACu-20Fe-12Cr alloy become faster than those of PMCu-20Fe-12Cr alloy because the reduction in the grain size of MACu-20Fe-12Cr alloy produces large concentrations of grain boundaries.

Effects of Compositions on the Chloride Ion Permeability of Geopolymer Concrete

2012 ◽  
Vol 450-451 ◽  
pp. 428-432
Author(s):  
Qing Wang ◽  
Jing Da ◽  
Cun Bao Zhang ◽  
Zhao Yang Ding ◽  
Zhi Tong Sui
Keyword(s):  
Chloride Ion ◽  
Cementitious Material ◽  
Molar Ratio ◽  
Geopolymer Concrete ◽  
Ion Permeability ◽  
Flux Method ◽  
Molar Ratios ◽  
Electric Flux ◽  
Better Than

The three key oxide molar ratios of geopolymer concrete were studied in this paper: n(SiO2)/n(Al2O3)，n(Na2O)/n(Al2O3) and n(H2O)/n(Na2O). The effect of each oxide molar ratio was assessed by electric flux method. It was found that resistance to chloride ion of geopolymer was increased with increasing n(SiO2)/n(Al2O3).However, there was a limit beyond which this performance improved; it performed better with the increasing of n(Na2O)/n(Al2O3) but worse with the increasing of n(H2O)/n(Na2O). With the same amount of cementitious material, resistance to chloride ion of geopolymer concrete was better than that of common concrete.

scholarly journals Sulfonated Hydrothermal Carbon-Based Catalyzed Esterification under Microwave Irradiation: Optimization and Kinetic Study

2020 ◽  
Vol 15 (2) ◽  
pp. 514-524
Author(s):  
Laddawan Tumkot ◽  
Armando T. Quitain ◽  
Tetsuya Kida ◽  
Navadol Laosiripojana ◽  
Artiwan Shotipruk ◽  
...  
Keyword(s):  
Microwave Irradiation ◽  
Reaction Rate Constant ◽  
Molar Ratio ◽  
Catalyst Loading ◽  
Esterification Reaction ◽  
Good Prediction ◽  
Molar Ratios ◽  
First Order Kinetics ◽  
A Value ◽  
Carbon Based

In this study, the esterification reaction of oleic acid (OA) with methanol was investigated in the presence of a sulfonated hydrothermal carbon-based catalyst under microwave irradiation. The reaction conditions were optimized using response surface methodology based on a central composite design. Three following variables were studied: methanol to OA molar ratios (2.5:1–7.5:1), reaction time (50–70 min) and catalyst loading (2–5 wt.%) to provide a statistical model with the coefficient of regression (R2) of 0.9407. Based on the model, the optimum OA conversion of 95.6% was predicted at 5.8:1 methanol to OA molar ratio, 60 min and 3.05 wt.% catalyst loading. The experimental validation indicated that the model gave a good prediction of OA conversion (2.8% error). Furthermore, the reaction was found to be reasonably described by the pseudo-first order kinetics. The dependency of the reaction rate constant on temperatures gave a value of the activation energy of 64 kJ/mol. Copyright © 2020 BCREC Group. All rights reserved 

scholarly journals Temperature dependent halogen activation by N2O5 reactions on halide-doped ice surfaces

2012 ◽  
Vol 12 (11) ◽  
pp. 5237-5247 ◽  
Author(s):  
F. D. Lopez-Hilfiker ◽  
K. Constantin ◽  
J. P. Kercher ◽  
J. A. Thornton
Keyword(s):  
Relative Yield ◽  
Chloride Ion ◽  
Chloride Ions ◽  
Molar Ratio ◽  
Ionization Mass ◽  
Polar Regions ◽  
Reaction Products ◽  
Starting Solution ◽  
Halogen Compounds ◽  
Almost All

Abstract. We examined the reaction of N2O5 on frozen halide salt solutions as a function of temperature and composition using a coated wall flow tube technique coupled to a chemical ionization mass spectrometer (CIMS). The molar yield of photo-labile halogen compounds was near unity for almost all conditions studied, with the observed reaction products being nitryl chloride (ClNO2) and/or molecular bromine (Br2). The relative yield of ClNO2 and Br2 depended on the ratio of bromide to chloride ions in the solutions used to form the ice. At a bromide to chloride ion molar ratio greater than 1/30 in the starting solution, Br2 was the dominant product otherwise ClNO2 was primarily produced on these near pH-neutral brines. We demonstrate that the competition between chlorine and bromine activation is a function of the ice/brine temperature presumably due to the preferential precipitation of NaCl hydrates from the brine below 250 K. Our results provide new experimental confirmation that the chemical environment of the brine layer changes with temperature and that these changes can directly affect multiphase chemistry. These findings have implications for modeling air-snow-ice interactions in polar regions and likely in polluted mid-latitude regions during winter as well.

scholarly journals Temperature dependent halogen activation by N<sub>2</sub>O<sub>5</sub> reactions on halide-doped ice surfaces

2012 ◽  
Vol 12 (2) ◽  
pp. 6085-6112 ◽  
Author(s):  
F. D. Lopez-Hilfiker ◽  
K. Constantin ◽  
J. P. Kercher ◽  
J. A. Thornton
Keyword(s):  
Relative Yield ◽  
Chloride Ion ◽  
Chloride Ions ◽  
Molar Ratio ◽  
Ionization Mass ◽  
Polar Regions ◽  
Reaction Products ◽  
Starting Solution ◽  
Halogen Compounds ◽  
Almost All

Abstract. We examined the reaction of N2O5 on frozen halide salt solutions as a function of temperature and composition using a coated wall flow tube technique coupled to a chemical ionization mass spectrometer (CIMS). The molar yield of photo-labile halogen compounds was near unity for almost all conditions studied, with the observed reaction products being nitryl chloride (ClNO2) and/or molecular bromine (Br2). The relative yield of ClNO2 and Br2 depended on the ratio of bromide to chloride ions in the solutions used to form the ice. At a bromide to chloride ion molar ratio greater than 1/30 in the starting solution, Br2 was the dominant product otherwise ClNO2 was primarily produced on these near pH-neutral brines. We demonstrate that the competition between chlorine and bromine activation is a function of the ice/brine temperature presumably due to the preferential precipitation of NaCl hydrates from the brine below 250 K. Our results provide new experimental confirmation that the chemical environment of the brine layer changes with temperature and that these changes can directly affect multiphase chemistry. These findings have implications for modeling air-snow-ice interactions in polar regions and likely in polluted mid-latitude regions during winter as well.

scholarly journals Experimental Study and Simulation Calculation of the Chloride Resistance of Concrete under Multiple Factors

2021 ◽  
Vol 11 (12) ◽  
pp. 5322
Author(s):  
Yang Ding ◽  
Tong-Lin Yang ◽  
Hui Liu ◽  
Zhen Han ◽  
Shuang-Xi Zhou ◽  
...  
Keyword(s):  
Hydrostatic Pressure ◽  
Penetration Depth ◽  
Chloride Ion ◽  
Cementitious Materials ◽  
Chloride Ions ◽  
Finite Element Software ◽  
Chloride Resistance ◽  
Simulation Calculation ◽  
Marine Concrete ◽  
Resistance Performance

Cement is widely used in marine concrete, and its resistance to chloride ion corrosion has been widely considered. In this paper, based on a laboratory test, the influence of different hydrostatic pressures, coarse aggregate contents and w/c ratios on the chloride resistance performance is analyzed. Based on COMSOL finite element software, a two-dimensional cementitious materials model is established, and the simulation results are compared with the experimental results. The results show that the penetration depth of chloride ions in cement increases with the increase of the w/c ratio. Under the hydrostatic pressure of 0 MPa, when the w/c ratio is 0.35, the penetration depth of chloride ions is 7.4 mm, and the simulation result is 8.0 mm. When the w/c ratio is 0.45, the penetration depth of chloride ions is 9.3 mm, and the simulation result is 9.9 mm. When the w/c ratio is 0.55, the penetration depth of chloride ions is 12.9 mm, and the simulation result is 12.1 mm. Under different hydrostatic pressures, the penetration depth of chloride ions obviously changes, and with the increase in hydrostatic pressure, the penetration depth of chloride ions deepens. Under the w/c ratio of 0.35, when the hydrostatic pressure is 0.5 MPa, the penetration depth of chloride ions is 11.3 mm, and the simulation result is 12.1 mm. When the hydrostatic pressure is 1.0 MPa, the penetration depth of chloride ions is 16.2 mm, and the simulation result is 17.5 mm.

scholarly journals Photocatalytic Reduction of CO2 to Methanol Using a Copper-Zirconia Imidazolate Framework

Catalysts ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 346
Author(s):  
Sonam Goyal ◽  
Maizatul Shima Shaharun ◽  
Ganaga Suriya Jayabal ◽  
Chong Fai Kait ◽  
Bawadi Abdullah ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Catalyst Support ◽  
Oxidation Potential ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
X Ray ◽  
Molar Ratios ◽  
Optimum Parameters ◽  
Reduction Of Co2 ◽  
Enhanced Yield

A set of novel photocatalysts, i.e., copper-zirconia imidazolate (CuZrIm) frameworks, were synthesized using different zirconia molar ratios (i.e., 0.5, 1, and 1.5 mmol). The photoreduction process of CO2 to methanol in a continuous-flow stirred photoreactor at pressure and temperature of 1 atm and 25 °C, respectively, was studied. The physicochemical properties of the synthesized catalysts were studied using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) spectroscopy. The highest methanol activity of 818.59 µmol/L.g was recorded when the CuZrIm1 catalyst with Cu/Zr/Im/NH4OH molar ratio of 2:1:4:2 (mmol/mmol/mmol/M) was employed. The enhanced yield is attributed to the presence of Cu2+ oxidation state and the uniformly dispersed active metals. The response surface methodology (RSM) was used to optimize the reaction parameters. The predicted results agreed well with the experimental ones with the correlation coefficient (R2) of 0.99. The optimization results showed that the highest methanol activity of 1054 µmol/L.g was recorded when the optimum parameters were employed, i.e., stirring rate (540 rpm), intensity of light (275 W/m2) and photocatalyst loading (1.3 g/L). The redox potential value for the CuZrIm1 shows that the reduction potential is −1.70 V and the oxidation potential is +1.28 V for the photoreduction of CO2 to methanol. The current work has established the potential utilization of the imidazolate framework as catalyst support for the photoreduction of CO2 to methanol.

scholarly journals Broadband dielectric spectroscopy for monitoring temperature-dependent chloride ion motion in BiOCl plates

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Adrian Radoń ◽  
Dariusz Łukowiec ◽  
Patryk Włodarczyk
Keyword(s):  
Electrical Conductivity ◽  
Dielectric Spectroscopy ◽  
Low Frequency ◽  
Chloride Ion ◽  
Ion Source ◽  
Chloride Ions ◽  
Ion Concentration ◽  
Broadband Dielectric Spectroscopy ◽  
Free Chloride ◽  
Structure Rebuilding

AbstractThe dielectric properties and electrical conduction mechanism of bismuth oxychloride (BiOCl) plates synthesized using chloramine-T as the chloride ion source were investigated. Thermally-activated structure rebuilding was monitored using broadband dielectric spectroscopy, which showed that the onset temperature of this process was 283 K. This rebuilding was related to the introduction of free chloride ions into [Bi2O2]2+ layers and their growth, which increased the intensity of the (101) diffraction peak. The electrical conductivity and dielectric permittivity were related to the movement of chloride ions between plates (in the low-frequency region), the interplanar motion of Cl− ions at higher frequencies, vibrations of these ions, and charge carrier hopping at frequencies above 10 kHz. The influence of the free chloride ion concentration on the electrical conductivity was also described. Structure rebuilding was associated with a lower concentration of free chloride ions, which significantly decreased the conductivity. According to the analysis, the BiOCl plate conductivity was related to the movement of Cl− ions, not electrons.

scholarly journals Lipozyme 435-Mediated Synthesis of Xylose Oleate in Methyl Ethyl Ketone

Molecules ◽  
2021 ◽  
Vol 26 (11) ◽  
pp. 3317
Author(s):  
Maria Carolina Pereira Gonçalves ◽  
Jéssica Cristina Amaral ◽  
Roberto Fernandez-Lafuente ◽  
Ruy de Sousa Junior ◽  
Paulo Waldir Tardioli
Keyword(s):  
Oleic Acid ◽  
Methyl Ethyl Ketone ◽  
Molar Ratio ◽  
Methyl Ethyl ◽  
Sugar Ester ◽  
Molar Ratios ◽  
Emulsion Capacity ◽  
Ping Pong ◽  
Commercial Sugar ◽  
Repeated Use

In this paper, we have performed the Lipozyme 435-catalyzed synthesis of xylose oleate in methyl ethyl ketone (MEK) from xylose and oleic acid. The effects of substrates’ molar ratios, reaction temperature, reaction time on esterification rates, and Lipozyme 435 reuse were studied. Results showed that an excess of oleic acid (xylose: oleic acid molar ratio of 1:5) significantly favored the reaction, yielding 98% of xylose conversion and 31% oleic acid conversion after 24 h-reaction (mainly to xylose mono- and dioleate, as confirmed by mass spectrometry). The highest Lipozyme 435 activities occurred between 55 and 70 °C. The predicted Ping Pong Bi Bi kinetic model fitted very well to the experimental data and there was no evidence of inhibitions in the range assessed. The reaction product was purified and presented an emulsion capacity close to that of a commercial sugar ester detergent. Finally, the repeated use of Lipozyme 435 showed a reduction in the reaction yields (by 48 and 19% in the xylose and oleic acid conversions, respectively), after ten 12 h-cycles.

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