scholarly journals Effect of Mg Concentration on the Aluminothermic Reduction of Mn2O3 Particles Obtained from Cathodes of Discharged Alkaline Batteries: Mathematical Modeling and Experimental Results

Metals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 49
Author(s):  
Orlando Flores Dávila ◽  
Jesús Torres Torres ◽  
Alfredo Flores Valdes
Keyword(s):  
Molten Aluminum ◽  
Treatment Time ◽  
Chemical Reduction ◽  
Reduction Reaction ◽  
Solid Particles ◽  
Experimental Results ◽  
Aluminothermic Reduction ◽  
Magnesium Concentration ◽  
Reaction Products ◽  
Alkaline Batteries

This paper aimed at studying the effect of magnesium concentration in molten aluminum produced from beverage cans on the process of aluminothermic reduction of Mn2O3 particles obtained from the cathodes of discharged alkaline batteries. The experimental results were analyzed by using thermodynamic fundamentals and kinetic modeling, while the characterization of the reaction products obtained allowed the mechanism of the process to be described. It was found that the addition of magnesium improves the wettability of solid particles by molten aluminum, thus increasing the reaction and its subsequent incorporation into the molten aluminum solution of Mn released from the reduction reaction. This work was carried out using several initial magnesium concentrations; 1.0, 2.0, 3.0, and 4.0 wt %, under a constant temperature of 1073 K, a constant treatment time of 240 min, and a constant agitation speed of 200 rpm. The results show that the higher the initial magnesium concentration in the molten alloy, the higher the speed of the chemical reduction reaction of the Mn2O3 particles.

Effects of Production Methods on the Particle Morphology and Properties of Aqueous Au Nanofluids

2012 ◽  
Author(s):  
Ji-Hwan Lee ◽  
Seoung Youn Lee ◽  
Hyun Jin Kim ◽  
Seung-Hyun Lee ◽  
Seok Pil Jang ◽  
...  
Keyword(s):  
Particle Size ◽  
Chemical Reduction ◽  
Particle Morphology ◽  
Production Method ◽  
Reduction Reaction ◽  
Experimental Results ◽  
Production Methods ◽  
Transmission Electron ◽  
Custom Made ◽  
Dispersion State

In this study, the effects of nanofluid production methods on the particle morphology and properties of aqueous gold (Au) nanofluids are investigated using chemical reduction (referred as Turkevich method). Sonication method is used to provide energy for the production of Au nanofluids. Applied energy to the production of nanofluids and temperature of the reduction reaction are two main parameters in the production of aqueous Au nanofluids, affecting the particle size and dispersion state of Au nanofluids even though same production method is used. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) are used to characterize particle size, shape and distribution. The thermal conductivities of Au nanofluids are measured by the custom-made transient hot wire system. Uncertainty of the measurements is less than ±1.5%. The pH and electrical conductivities are also measured by commercial products in this study. Temperature range of measuring properties is 10–30 °C. Experimental results show that production methods can affect the particle morphology and transport properties of Au nanofluids. Sizes of produced Au nanoparticles are 20–40 nm depending on the production methods and parameters. Through characterization and experimental results of Au nanofluids, we found the optimum conditions for production of aqueous Au nanofluids which have high thermal conductivity, small particle size and well dispersed characteristics.

A Comparative Study of SHS Synthesis of TiB2 Cermets Powder by Magnesium Reduction and Aluminothermy Reduction

2012 ◽  
Vol 567 ◽  
pp. 33-36
Author(s):  
Hai Bo Wang ◽  
Xi Bao Wang ◽  
Hui Li
Keyword(s):  
Comparative Study ◽  
Reduction Reaction ◽  
Impurity Phase ◽  
Aluminothermic Reduction ◽  
Metal Reduction ◽  
Reaction Products ◽  
Pickling Process ◽  
Arc Heating

In this paper, metal reduction preparation of TiB2 powder via magnesium reduction and aluminothermic reduction were studied. The carbon rod arc heating generated from the spread of the reaction of TiB2，and then the examinations were performed after pickling, crushing and grinding such as SEM and XRD. The results showed that the aluminothermic reduction occurred into the powder impurity phase less, but the need for better technology separation of Al2O3. Magnesium reduction reaction products with more impurities, pickling process removes only the reactants of MgO and other impurities not removed in the air and impurities were analyzed and compared.

scholarly journals A Kinetic Study on the Preparation of AlNi Alloys by Aluminothermic Reduction of NiO Powders

Metals ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 675
Author(s):  
Cesar Beltran ◽  
Alfredo Valdes ◽  
Jesús Torres ◽  
Rocio Palacios
Keyword(s):  
Agitation Speed ◽  
Aluminothermic Reduction ◽  
Magnesium Concentration ◽  
Main Reaction ◽  
Powder Injection ◽  
Reaction Products ◽  
Mechanical Agitation ◽  
Melt Temperature ◽  
Kinetics Of ◽  
Parameters Of Interest

In this work, the experimental results obtained during the preparation of Al-Ni and Al-Ni-Mg alloys using the aluminothermic reduction of NiO by submerged powder injection, assisted with mechanical agitation are presented and discussed. The analyzed variables were melt temperature, agitation speed, and initial magnesium concentration in the molten alloy. For some of the experiments performed, it was found that the Ni concentration increased from 0 to about 3 wt-% after 90 min of treatment at constant temperature and constant agitation speed. In order to determine the values of the kinetic parameters of interest, such as the activation energy and the rate constants, the values of the results obtained were fitted to the kinetic formulae available. Moreover, the kinetics of the reaction were found to be governed by the diffusion of Al and Mg to the NiO boundary layer, where MgAl2O4 or Al2O3 were formed as the main reaction products. Finally, from a thermodynamic study of the system, the main reactions that took place are explained.

Aluminothermic Synthesis of Al2O3/ZrO2/SiC Composite Powders

1991 ◽  
Vol 249 ◽  
Author(s):  
J.P. Erauw
Keyword(s):  
Morphological Characteristics ◽  
Xrd Analysis ◽  
Reaction Scheme ◽  
Adiabatic Temperature ◽  
Experimental Results ◽  
Aluminothermic Reduction ◽  
Reaction Products ◽  
Composite Powders

ABSTRACTThe synthesis of Al2O3/ZrO2/ SiC composite powders by aluminothermic reduction of zircon in the presence of carbon is reported. The effect of the temperature on the progress of the reaction, as assessed by XRD analysis, is outlined. The morphological characteristics of the reaction products are described. Based on the experimental results, a reaction scheme is proposed. The possible propagation of the reaction is discussed in terms of the adiabatic temperature.

A new method for monitoring the redox potential of fuel salt based on the deposition of 95Nb on Hastelloy C276

2021 ◽  
Vol 109 (5) ◽  
pp. 357-365
Author(s):  
Zhiqiang Cheng ◽  
Zhongqi Zhao ◽  
Junxia Geng ◽  
Xiaohe Wang ◽  
Jifeng Hu ◽  
...  
Keyword(s):  
Redox Potential ◽  
Molten Salt ◽  
Specific Activity ◽  
Chemical Reduction ◽  
Quantitative Approach ◽  
Experimental Results ◽  
New Method ◽  
Molten Salt Reactor ◽  
Fuel Salt ◽  
Well Correlation

Abstract To develop the application of 95Nb as an indicator of redox potential for fuel salt in molten salt reactor (MSR), the specific activity of 95Nb in FLiBe salt and its deposition of 95Nb on Hastelloy C276 have been studied. Experimental results indicated that the amount of 95Nb deposited on Hastelloy C276 resulted from its chemical reduction exhibited a positive correlation with the decrease of 95Nb activity in FLiBe salt and the relative deposition coefficient of 95Nb to 103Ru appeared a well correlation with 95Nb activity in FLiBe salt. Both correlations implied that the measurement of 95Nb activity deposited on Hastelloy C276 specimen might provide a quantitative approach for monitoring the redox potential of fuel salt in MSR.

Reduction of NO2 in N2 by Non-Thermal Plasmas

1997 ◽  
Vol 2 (2) ◽  
Author(s):  
M. C. Hsiao ◽  
B. M. Penetrante ◽  
B. T. Merritt ◽  
G. E. Vogtlin ◽  
P. H. Wallman
Keyword(s):  
Chemical Reduction ◽  
Thermal Plasmas ◽  
Experimental Results

AbstractExperimental results on the chemical reduction of dilute concentrations of NO

Multi-Walled Carbon Nanotubes as Electrocatalyst Supports for H2O2 Reduction Reaction

2013 ◽  
Vol 860-863 ◽  
pp. 831-834
Author(s):  
Dan Zheng ◽  
Ting Fang Yang ◽  
Zhang Fei Guo
Keyword(s):  
Cyclic Voltammetry Curve ◽  
Chemical Reduction ◽  
Reduction Reaction ◽  
Carbon Substrate ◽  
Acid Media ◽  
Multi Walled Carbon Nanotube ◽  
Multi Walled Carbon Nanotubes ◽  
Current Densities ◽  
Reaction Activation Energy ◽  
Walled Carbon Nanotubes

This work studies the use of Multi-walled carbon nanotube (MWCNT) as catalyst supports for H2O2 electro-reduction in acid media. Using impregnation-chemical reduction method, we prepared Pt-Ag/CNTs, Pt-Co/CNTs, Pt-Ag/C and Pt-Co/C nanocatalysts. Four catalysts were analyzed by XRD and TEM. Their electrochemical performance was studied via cyclic voltammetry curve. The results show that: the nanoparticles have a better dispersion on CNTs substrate than on XC-72 carbon substrate. Comparing with Pt-Ag and Pt-Co on XC-72 carbon substrate, the H2O2 reduction reaction activation energy of catalysts on CNTs substrate is bigger, and the peak current densities of catalysts on CNTs substrate are larger than that on XC-72 carbon.

scholarly journals ELECTROCHEMICAL ACTIVITY OF PtM (M=Co, Cu, Ni) CATALYSTS SUPPORTED ON CARBON VULCAN FOR OXYGEN REDUCTION REACTION (ORR) IN FUEL CELLS

2018 ◽  
Vol 56 (2A) ◽  
pp. 81-88 ◽  
Author(s):  
Vu Thi Hong Phuong
Keyword(s):  
Fuel Cell ◽  
Proton Exchange Membrane ◽  
Chemical Reduction ◽  
Low Cost ◽  
Reduction Reaction ◽  
Proton Exchange ◽  
Carbon Powder ◽  
Galvanic Replacement ◽  
H2o2 Formation ◽  
Cost Efficient

PEMFC - proton exchange membrane fuel cell is electrochemical devices producing electricity and heat from reaction between a fuel (often hydrogen) and oxygen. Therefore, energy production is generally clean and effective without burning the fuel like the tradition way in combustion engines. The obstacles encountered fuel cell commercialization are mainly due to expensive catalyst materials (Platinum) and long-term instability performance. For this reason, numerous investigations have been undertaken with the goal of developing low-cost, efficient electrocatalysts that can be used as alternatives to Pt. In this paper, a two-step procedure at room temperature was applied to prepare a bimetallic Pt-M(M = metal) supported carbon Vulcan. First, the chemical reduction of M metal ions by sodium borohydride in the presence of carbon powder is performed. Second, the partial galvanic replacement of M particle layers by Pt is achieved upon immersion in a chloroplatinate solution. The major size of synthesized metallic particles was around 2-3 nm. From the slope of Koutecky-Levich plot for ORR using PtM/C materials as catalysts it was found that the overall electron transfer number ranged from 3 to 4, leading to the suggestion of H2O2 formation as an intermediate of the ORR.

Optimization of Agar Preparation Based on Transparency

2021 ◽  
Vol 1033 ◽  
pp. 103-108
Author(s):  
Ying Cai ◽  
Zhan Xia Wu ◽  
Zhao Yu Zhang ◽  
Zhang Hu
Keyword(s):  
Activated Carbon ◽  
Treatment Time ◽  
Orthogonal Experiment ◽  
Economic Benefits ◽  
Experimental Results ◽  
Practical Significance ◽  
Process Conditions ◽  
Processing Temperature ◽  
Experimental Conditions ◽  
Filtration Method

To meet the requirement for high transparency of agar gel used in tissue culture, bacteriological applications, and high-quality cosmetics and food, this study on improving the transparency of agar products was carried out by using activated carbon for decolorization and perlite for aiding filtration. The results showed that the pre-coating filtration method was better than that of the mixed slurry filtration, so an orthogonal experiment optimization was conducted using the pre-coating filtration method based on the single factor experimental results. The experimental results showed that the optimal process conditions based on the transparency index were: concentration of agar of 1.30%, activated carbon dosage of 0.80%, processing temperature of 95 °C, and treatment time of 20 min. Agar products with gel transparency of 58.93% and blue-ray whiteness value of 93.82 could be obtained under these experimental conditions. The order of the factors influencing the decolorization ratio of agar was as follows: activated carbon dosage > concentration of agar > processing temperature > treatment time. The experimental results provided effective procession methods for the production enterprises based on transparency and increased economic benefits, and it was of practical significance.

Solids Distribution in Sediment-Laden Open-Channel Flow: Experiment and Prediction

2020 ◽  
Author(s):  
Václav Matoušek ◽  
Jan Krupička ◽  
Tomáš Picek ◽  
Štěpán Zrostlik
Keyword(s):  
Channel Flow ◽  
Open Channel ◽  
Transport Model ◽  
Plane Surface ◽  
Open Channel Flow ◽  
Solid Particles ◽  
Experimental Results ◽  
Transport Layer ◽  
Experimental Investigations ◽  
Solids Concentration

Abstract Solid-liquid flow is studied in an open channel with a mobile bed at the condition of intense transport of solids. It is flow of high-concentrated mixture of coarse sediment and water over a plane surface of the bed eroded due to high bed shear. In the flow, solid particles are non-uniformly distributed across the flow depth. The flow develops a transport layer, adjacent to the the top of the bed, in which transported particles interact with each other. Results are presented of experimental investigations of the sediment-laden open-channel flow in a recirculating titling flume. The experiments included measurements (using ultrasonic techniques) of the distribution of solids velocity across the transport layer. The related distribution of solids concentration was deduced from the measured distribution of velocity and from other measured flow quantities. Since recently, a direct measurement of the solids distribution across the transport layer has been added to the experiments using a measuring technique svideo camera and a laser sheet. This work discusses results of combined measurements of the distributions of solids concentration and velocity in steady uniform turbulent flow for two lightweight solids fractions and various flow conditions (a broad range of the bed Shields parameter, discharge of solids, discharge of mixture, and the longitudinal slope of the bed). Furthermore, the camera-based measuring method and the deducing method for a determination of solids distribution are discussed and their results compared to show a good agreement in a majority of the test runs. The experimental results are compared with predictions of a recently developed bed-load transport model. Among other outputs, the model predicts the position of the top of the transport layer and the local velocity of sediment particles at this position. The presented model predictions agree well with experimental results based on the measured distibutions.

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