The electrochemical reduction mechanism of Fe3O4 in NaCl-CaCl2 melts

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Hui Li ◽  
Lei Jia ◽  
Weigang Cao ◽  
Jinglong Liang ◽  
Le Wang ◽  
...  
Keyword(s):  
Electrochemical Method ◽  
Early Stage ◽  
Cell Voltage ◽  
Transformation Process ◽  
Main Reaction ◽  
Electrolysis Time ◽  
Reduction Mechanism ◽  
Step Process ◽  
Constant Cell ◽  
Electrolysis Products

AbstractIn order to study the process of Fe3O4 reduction by melt electro-deoxidation. Electrochemical method was used to analyze the reduction mechanism of Fe3O4 in NaCl-CaCl2 melts. The effects of cell voltage and time on the product were discussed through constant cell voltage electrolysis. The results showed: (1) The reduction of solid Fe3O4 to metallic Fe is a two-step process for obtaining electrons. (2) The transformation process (600 min, 0–1.0 V) of the electrolysis products with the increase of the cell voltage is as follows: Fe3O4 → FeO → FeO + Fe → Fe. (3) The intermediate product Ca2Fe2O5 was formed (2.0 V, 10–300 min), which inhibited the deoxygenation process in the early stage of the reaction. When the electrolysis time exceeds 60 min, the main reaction is the reduction of Ca2Fe2O5 to Fe.

An Electrochemical Method for the Preparation of Al-Mg Master Alloys from MgO

2010 ◽  
Vol 650 ◽  
pp. 260-264 ◽  
Author(s):  
Da Li Cao ◽  
Ji Kun Wang ◽  
Si Chen Guo ◽  
Qin Hong Fang ◽  
Zhong Ning Shi
Keyword(s):  
Formation Mechanism ◽  
Master Alloy ◽  
Phase Structure ◽  
Electrochemical Method ◽  
Single Phase ◽  
Cell Voltage ◽  
Electrolysis Time ◽  
Electrolysis Process ◽  
Master Alloys ◽  
Mg Content

The electrochemical formation of Al-Mg master alloys were investigated in NaCl-MgF2-MgO melt at 850°C. The results revealed that cell voltage was nearly constant during electrolysis process, Mg content in Al-Mg master alloys increased with increasing of electrolysis time when Mg content was less 7.03mass%, Mg content in Al-Mg master alloys can be up to 7.03mass% for 4h electrolysis. The results of XRD indicated that phase structure of the Al-7.03Mg mass% alloy existed single phase α-Al, MgCl2 and NaMgF3 in electrolyte were observed after electrolysis. And the formation mechanism of Al-Mg master alloy was discussed as well.

Electrochemical recovery of Ni metallic in molten salts from spent lithium-ion battery

2020 ◽  
Vol 18 (8) ◽  
Author(s):  
Jinglong Liang ◽  
Jing Wang ◽  
Hui Li ◽  
Chenxiao Li ◽  
Hongyan Yan ◽  
...  
Keyword(s):  
Molten Salt ◽  
Lithium Ion Battery ◽  
Electrochemical Reduction ◽  
Lithium Ion ◽  
Cell Voltage ◽  
Metallic Nickel ◽  
Molten Salt Electrolysis ◽  
Reduction Behavior ◽  
Urgent Task ◽  
Constant Cell

AbstractMassive deployment of lithium-ion battery inevitably causes a large amount of solid waste. To be sustainably implemented, technologies capable of reducing environmental impacts and recovering resources from spent lithium-ion battery have been an urgent task. The electrochemical reduction of LiNiO2 to metallic nickel has been reported, which is a typical cathode material of lithium-ion battery. In this paper, the electrochemical reduction behavior of LiNiO2 is studied at 750 °C in the eutectic NaCl-CaCl2 molten salt, and the constant cell voltage electrolysis of LiNiO2 is carried out. The results show that Ni(III) is reduced to metallic nickel by a two-step process, Ni(III) → Ni(II) → Ni, which is quasi-reversible controlled by diffusion and electron transfer. After electrolysis for 6 h at 1.4 V, the surface of LiNiO2 cathode is reduced to metallic nickel, with NiO and a small amount of Li0.4Ni1.6O2 detected inside the partially reduced cathode. After prolonging the electrolysis time to 12 h, LiNiO2 is fully electroreduced to metallic nickel, achieving a high current efficiency of 98.60%. The present work highlights that molten salt electrolysis could be an effective protocol for reclamation of spent lithium-ion battery.

scholarly journals Kinetics of CxNy formation on electrode surface using the electrochemical method

2008 ◽  
Vol 40 (2) ◽  
pp. 147-154
Author(s):  
A. Chekhovskii ◽  
T. Tomila ◽  
A. Ragulya ◽  
I. Timofeeva ◽  
A. Ivanchuk ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Ir Spectroscopy ◽  
Electrode Material ◽  
Electrode Surface ◽  
Electrochemical Method ◽  
Deposition Process ◽  
Absorption Bands ◽  
X Ray ◽  
Kinetics Of ◽  
Electrolysis Products

Powded CxNy coatings were deposited from acetonitrile on Ni, Si, and C surfaces at a voltage 500-2000 V by the electrochemical method. Electrolysis products were analyzed by IR spectroscopy, X-ray phase analysis and electron microscopy. According to FTIR data, at frequencies 1370 and 1530 cm-1, absorption bands characteristic for stretching C-N and C=N oscillations are observed. The obtained results indicate that the deposition process occurs in a different manner in each specific case, i.e., the kinetics of the electrode depends on the electrode material (Ni, Si, and C).

Preparation of Al-Sc Alloy by LiF-ScF3-ScCl3 Molten Salt Electrolysis

2011 ◽  
Vol 675-677 ◽  
pp. 1125-1128 ◽  
Author(s):  
Rui Guo ◽  
Xiu Jing Zhai ◽  
Ting An Zhang
Keyword(s):  
Molten Salt ◽  
Base Alloy ◽  
Process Condition ◽  
Cell Voltage ◽  
Scandium Oxide ◽  
Raw Material ◽  
Electrolysis Time ◽  
Molten Salt Electrolysis ◽  
Aluminum Base Alloy ◽  
Aluminum Base

The paper studied the preparation of Al-Sc alloy by molten salt electrolysis. LiF-ScF3-ScCl3 as the electrolyte, Sc2O3 as raw material, liquid Al as cathode and graphite as anode. The process condition of preparating Al-Sc alloy includes the influence of current density, electrolysis time, temperature of electrolysis, Back EMF, content of Sc in alloy and current efficiency.The content of Sc in alloy prepared by this method has reached to the maximum of 3.437%. The components of alloys showed by SEM were uniform, it is applicable for commercial purposes. Preparation of Al-Sc alloys with scandium oxide as raw materials, it not only reduce environment pollution, but also decease the cost of production. It is reported in many documents, preparing aluminum base alloy by the method of molten salt electrolysis[1-3], people could make many alloys such as Al-Ce、Al-La、Al-RE、Al-Ti、Al-Si-Ti in the aluminum cell, also the method to prepare some rare earth alloys such as Al-Sr、Nd-Fe、La-Ni was reported[4,5]. Use the method of electrolysis to produce some aluminum base alloy with high-melting-point , difficult to restore , high-priced element is a good method because it is technological process is brief, economy is rational, the technology is feasible, this viewpoint is broadly approved in the world[6]. It isn’t necessary to use high-priced Sc as raw material in preparing Al-Sc alloy with molten salt electrolysis, it could control the Sc amounts in the alloy through the different current efficiency and electrolysis time, production in this method could be continuous or semi-continuous, so it is easy to be automatic controlled. A new molten salt system is used in this paper, we use molten salt electrolysis to produce Al-Sc alloy, take scandium oxide as raw material, through the study of the effect of the current intensity，electrolysis time and the electrolysis temperature , Back EMF and cell voltage, the final production Al-Sc alloy contains Sc 2~6%.

scholarly journals Use of Coal Bottom Ash and CaO-CaCl2-Activated GGBFS Binder in the Manufacturing of Artificial Fine Aggregates through Cold-Bonded Pelletization

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5598
Author(s):  
Dongho Jeon ◽  
Woo Sung Yum ◽  
Haemin Song ◽  
Seyoon Yoon ◽  
Younghoon Bae ◽  
...  
Keyword(s):  
Early Stage ◽  
Bottom Ash ◽  
Relative Weight ◽  
Main Reaction ◽  
Reaction Products ◽  
Coal Bottom Ash ◽  
Heavy Metal Leaching ◽  
Granulated Blast Furnace Slag ◽  
Fine Aggregates ◽  
Cementless Binder

This study investigated the use of coal bottom ash (bottom ash) and CaO-CaCl2-activated ground granulated blast furnace slag (GGBFS) binder in the manufacturing of artificial fine aggregates using cold-bonded pelletization. Mixture samples were prepared with varying added contents of bottom ash of varying added contents of bottom ash relative to the weight of the cementless binder (= GGBFS + quicklime (CaO) + calcium chloride (CaCl2)). In the system, the added bottom ash was not simply an inert filler but was dissolved at an early stage. As the ionic concentrations of Ca and Si increased due to dissolved bottom ash, calcium silicate hydrate (C-S-H) formed both earlier and at higher levels, which increased the strength of the earlier stages. However, the added bottom ash did not affect the total quantities of main reaction products, C-S-H and hydrocalumite, in later phases (e.g., 28 days), but simply accelerated the binder reaction until it had occurred for 14 days. After considering both the mechanical strength and the pelletizing formability of all the mixtures, the proportion with 40 relative weight of bottom ash was selected for the manufacturing of pilot samples of aggregates. The produced fine aggregates had a water absorption rate of 9.83% and demonstrated a much smaller amount of heavy metal leaching than the raw bottom ash.

The Preparation of Size-Controlled Antimony Nanoparticles by Electrochemical Method

2013 ◽  
Vol 562-565 ◽  
pp. 716-720
Author(s):  
Jian Lin Xu ◽  
Jia Wang ◽  
Li Hui Zhang ◽  
Lei Niu ◽  
Jian Bin Zhang ◽  
...  
Keyword(s):  
Particle Size ◽  
Current Density ◽  
Electrochemical Method ◽  
Infrared Absorption Spectrum ◽  
Average Diameter ◽  
Electrolysis Time ◽  
Electrochemical Technology ◽  
Transmission Electron ◽  
Means Of Transmission ◽  
Size Controlled

This paper prepared some antimony nanoparticles with different particle size by electrochemical method. A method of preparing size-controlled antimony nanoparticles was established in the hydrochloric acid solution, which alkyphenol ethoxylates emulsifier was used as surface dispersants by electrochemical technology based on the optimization of the preparation technology. Those obtained antimony nanoparticles was characterized and analyzed by means of transmission electron microscopy (TEM), Fourier transform infrared absorption spectrum (FT-IR), X-ray diffraction (XRD). The experiment results show that alkyphenol ethoxylates emulsifier can effectively coat on the surface of antimony nanoparticles, current density and electrolysis time have an important influence on the particle size of those obtained antimony nanoparticles. When the current density is 25mA/cm2 and electrolysis time is 30minutes, spherical antimony nanoparticles with an average diameter of 12nm and good dispersion can be prepared.

Alkali-Heat Treatment of Ti-6Al-4V to Hydroxyapatite Coating Using Electrophoretic Method

2020 ◽  
Vol 846 ◽  
pp. 175-180 ◽  
Author(s):  
Sugeng Supriadi ◽  
Sri Lubriandini Putri ◽  
Rizkijanuar Ramadhan ◽  
Bambang Suharno
Keyword(s):  
Heat Treatment ◽  
Room Temperature ◽  
Alkali Treatment ◽  
Cell Voltage ◽  
Deposition Process ◽  
Vacuum Furnace ◽  
Electrophoretic Method ◽  
Coating Delamination ◽  
Constant Cell ◽  
Poor Adhesion

The deposition of hydroxyapatite has been applied to enhance the bioactivity of Ti-6Al-4V as implant materials. However, the hydroxyapatite has poor adhesion strength to a substrate which can lead to coating delamination. In this study, we combine the alkali-heat treatment of Ti-6Al-4V and the electrophoretic coating process of the hydroxyapatite to obtain the strong mechanical interlocking. The Ti-6Al-4V implants were etched in Kroll solution before the alkali-treatment was performed using 5M and 10M NaOH at 24, 48 and 72 hours and thermally stabilized at 600°C and 800°C for 1 hour using a stepwise heating rate of 5°C per min. The electrophoretic deposition process conducted at a constant cell voltage of 20 V for 10 min at room temperature and then sintered in a vacuum furnace at 800°C. The result shows that the feather-like structure on Ti-6Al-4V surface was created by incorporating sodium ions onto the Ti-6Al-4V surface during alkali-treatment using NaOH 5M for 48h and stabilized using heat treatment at 600°C where the hydroxyapatite filled the interspaces to become integrated with the feather-like structure so that the osseointegration can occur as the bioactivity increased.

Kaolinization of 2:1 type clay minerals with different swelling properties

2020 ◽  
Vol 105 (5) ◽  
pp. 687-696 ◽  
Author(s):  
Shangying Li ◽  
Hongping He ◽  
Qi Tao ◽  
Jianxi Zhu ◽  
Wei Tan ◽  
...  
Keyword(s):  
Clay Minerals ◽  
Early Stage ◽  
Transformation Process ◽  
Mineral Particle ◽  
Transformation Mechanism ◽  
Swelling Properties ◽  
Swelling Clay ◽  
Intermediate Phases ◽  
Swelling Clay Minerals ◽  
Study Laboratory

Abstract Kaolinization of 2:1 type clay minerals commonly occurs in the supergene environments of the Earth, which plays critical roles in many geochemical and environmental processes. However, the transformation mechanism involved and the specific behavior of 2:1 type swelling and non-swelling clay minerals during kaolinization remain poorly understood. In this study, laboratory experiments on the kaolinization of montmorillonite (swelling), illite (non-swelling), and rectorite (partially swelling) were carried out to investigate the kaolinization mechanism of 2:1 type clay minerals and to evaluate whether swelling and non-swelling layers of 2:1 type clay minerals perform differently or not in their kaolinization processes. The results show that montmorillonite, illite, and rectorite in acidic Al3+-containing solutions can be transformed into kaolinite, whereas such transformation is hard to take place in Al3+-free solutions. Part of the Al3+ in the solutions was exchanged into the interlayer spaces of swelling clay minerals at the early stage and resulted in the formation of hydroxy-aluminosilicate (HAS) interlayers, but they show no influence on the transformation process. Interstratified kaolinite-smectite (K-S), kaolinite-illite (K-I), and kaolinite-rectorite (K-R) formed as the intermediate phases during the transformations of the three different precursor minerals, respectively. The results obtained in this study demonstrate that 2:1 type clay minerals, including both swelling and non-swelling ones, can be transformed into kaolinite via a local dissolution-crystallization mechanism, which starts mainly from the layer edges rather than the basal surfaces. Due to different dissolution rates from domain to domain within a precursor mineral particle, the layers with a low dissolution rate become “splints,” while the dissolved elements are concentrated between two “splints,” leading to precipitation of kaolinite along the basal surfaces of precursor minerals. The size and stacking order of the newly formed kaolinite strongly depend on the morphology and property of the precursor minerals. These findings not only are of importance for better understanding the transformation procedures between different clay minerals and the mechanisms involved but also provide new insights for well understanding mineral-water interactions that are central to all geochemical processes.

β-Adrenergic modulation of L-type Ca2+-channel currents in early-stage embryonic mouse heart

1999 ◽  
Vol 276 (2) ◽  
pp. H608-H613 ◽  
Author(s):  
Weiran Liu ◽  
Kenji Yasui ◽  
Akiko Arai ◽  
Kaichiro Kamiya ◽  
Jianhua Cheng ◽  
...  
Keyword(s):  
Action Potential ◽  
Ventricular Myocytes ◽  
Early Stage ◽  
Cell Voltage ◽  
Mouse Heart ◽  
Embryonic Mouse ◽  
Adrenergic Modulation ◽  
Beating Rate ◽  
Β Adrenergic Receptors ◽  
Channel Currents

Little information is available concerning the modulation of cardiac function by β-adrenergic agonists in early-stage embryonic mammalian heart. We have examined the effects of isoproterenol (Iso) on the spontaneous beating rate and action potential (AP) configuration in embryonic mouse hearts at 9.5 days postcoitum (dpc), just 1 day after they started to beat. Iso (3 μM) increased the spontaneous beating rate in whole hearts, dissected ventricles, and isolated ventricular myocytes. In ventricular myocytes, Iso also increased the slope of the pacemaker potential and the action potential duration but decreased the maximum upstroke velocity. In whole cell voltage-clamp experiments, the Ca2+-channel currents were measured as Ba2+ currents ( I Ba). In 9.5-dpc myocytes, I Ba was enhanced significantly from −4.7 ± 0.9 to −6.7 ± 1.2 pA/pF (by 52.4 ± 14.8%, n = 10) after the application of Iso. Propranolol (3 μM) reversed the effect of Iso. Forskolin (For, 10 μM) produced an increase in I Ba by 95.5 ± 18.8% ( n = 8). In ventricular myocytes at a late embryonic stage (18 dpc), 3 μM Iso caused an appreciably greater increase in I Ba from −6.2 ± 0.5 to −14.5 ± 2.2 pA/pF (by 137.8 ± 33.0%, n = 8), whereas the increase in I Ba by 10 μM For (by 120.0 ± 23.0%, n = 7) was comparable to that observed in the early stage (9.5 dpc). These results indicate that the L-type Ca2+-channel currents are modulated by β-adrenergic receptors in the embryonic mouse heart as early as 9.5 dpc, probably via a cAMP-dependent pathway.

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