scholarly journals A STUDY ON THE KINETICS OF OXYGEN REDUCTION FOCOAR

2018 ◽  
Vol 55 (5B) ◽  
pp. 111
Author(s):  
Le Quoc Khanh
Keyword(s):  
Oxygen Reduction ◽  
Oxygen Concentration ◽  
Reduction Rate ◽  
Reduction Process ◽  
Oxygen Depletion ◽  
Reducing Agent ◽  
Time Interval ◽  
Low Oxygen ◽  
Living Organisms ◽  
Kinetics Of

          In poor oxygenated environments the oxidation and growth of the living organisms are slowed or stopped, so that food is better preserved. The most appropriate method for oxygen depletion in the air-tight minienvironment is oxygen reduction with iron-based reducing agent, which can reduce the air oxygen concentration to about 0 %, and maintain this low oxygen concentration long during storage. This paper studies the kinetics of oxygen reduction by reducing agent FOCOAR in an airtight minienvironment under isobaric conditions. The kinetics of the reduction process calculated according to the relation vav = [21 % - (end) ] / tend, in which vav is average reduction rate, (end) is oxygen concentration at the end of the experiment, tend is total time needed for the oxygen reduction experiment. Instantaneous reduction rate vred was calculated according to equation vred = ∆/△t, in which ∆is oxygen concentration reduced in time △t, and △t = ti+1 - ti is time interval for oxygen reduction. It is found that vav depends on the quantity of reducing agent FOCOAR, and in certain time interval varies as linear function of reduction time, corresponding to constant vred.  The kinetic result allows an estimating the amount of the reducing agent FOCOAR needed for a preserve minienvironment.

scholarly journals Reduction Mechanism of Fine Hematite Ore Particles in Suspension

2021 ◽  
Author(s):  
Zhiyuan Chen ◽  
Christiaan Zeilstra ◽  
Jan van der Stel ◽  
Jilt Sietsma ◽  
Yongxiang Yang
Keyword(s):  
Particle Size ◽  
Temperature Drop ◽  
Reduction Rate ◽  
Reduction Process ◽  
Reciprocal Relationship ◽  
Drop Tube ◽  
Surface Nucleation ◽  
Order Of Magnitude ◽  
Relationship Of ◽  
Kinetics Of

AbstractIn order to understand the pre-reduction behaviour of fine hematite particles in the HIsarna process, change of morphology, phase and crystallography during the reduction were investigated in the high temperature drop tube furnace. Polycrystalline magnetite shell formed within 200 ms during the reduction. The grain size of the magnetite is in the order of magnitude of 10 µm. Lath magnetite was observed in the partly reduced samples. The grain boundary of magnetite was reduced to molten FeO firstly, and then the particle turned to be a droplet. The Johnson-Mehl-Avrami-Kolmogorov model is proposed to describe the kinetics of the reduction process. Both bulk and surface nucleation occurred during the reduction, which leads to the effect of size on the reduction rate in the nucleation and growth process. As a result, the reduction rate constant of hematite particles increases with the increasing particle size until 85 µm. It then decreases with a reciprocal relationship of the particle size above 85 µm.

Metallurgical Behavior of Adjusted Converter Slag in Reduction Process

2011 ◽  
Vol 299-300 ◽  
pp. 310-313
Author(s):  
Min Chen ◽  
Zhen Tian ◽  
Qing Xian Yu ◽  
Zhen Feng Gao
Keyword(s):  
Mass Fraction ◽  
Slag Composition ◽  
Converter Slag ◽  
Reduction Rate ◽  
Selective Reduction ◽  
Reduction Process ◽  
Reducing Agent ◽  
Metal Phase ◽  
Reduction Temperature

The metallurgical behavior of adjusted converter slag components during the selective reduction process were investigated by thermodynamic calculating with different modified slag composition, addition of reducing agent and reduction temperature. The activities of main slag components were drawn from the calculated values. The results showed that the activity of SiO2increased with increment of its mass fraction in slag. The solubility of SiO2increased with increment of temperature. The selective reduction was promoted by selecting the appropriate amount of modifier. Reduction order was elucidated in this paper, Fe was reduced from the slag followed by P, Mn and Si and the reduction rate of Si could reach about 51%. The metal phase was rich in Fe, Si, Mn and P as a result of the selective reduction.

scholarly journals Kinetics of extracting magnesium from prefabricated pellets by silicothermic process under flowing argon atmosphere

2020 ◽  
pp. 31-31
Author(s):  
J.-H. Guo ◽  
D.-X. Fu ◽  
J.-B. Han ◽  
Z.-H. Ji ◽  
Z.-H. Dou ◽  
...  
Keyword(s):  
Diffusion Process ◽  
Atmospheric Pressure ◽  
Gas Flow ◽  
Continuous Production ◽  
Reduction Rate ◽  
Reduction Process ◽  
Control Step ◽  
Isothermal Kinetic ◽  
Carrier Gas Flow ◽  
Kinetics Of

The Pidgeon process is the main extraction method of magnesium, but its continuous production cannot be achieved due to the switch between vacuum and atmospheric pressure. Therefore, it is vital to realize continuous extraction of magnesium under atmospheric pressure. In this paper, the process of extracting magnesium from prefabricated pellets in flowing argon was proposed. The isothermal kinetic analysis of the reduction process was carried out, the results showed that the reduction process was controlled by diffusion process in 1 h, and the apparent activation energy of extracting magnesium from prefabricated pellets in flowing argon was 218.75 kJ/mol. Then the influence of experimental factors on the reduction rate was explored, including briquetting pressure, carrier gas flow rate, ferrosilicon content, reaction temperature and time. Through analysis and calculation, it was concluded that the main control step of diffusion process was silicon diffusion.

scholarly journals Statistical Optimisation and Kinetic Studies of Molybdenum Reduction Using a Psychrotolerant Marine Bacteria Isolated from Antarctica

2021 ◽  
Vol 9 (6) ◽  
pp. 648
Author(s):  
Syazani Darham ◽  
Khadijah Nabilah Mohd Zahri ◽  
Azham Zulkharnain ◽  
Suriana Sabri ◽  
Claudio Gomez-Fuentes ◽  
...  
Keyword(s):  
Marine Bacteria ◽  
Culture Media ◽  
Reduction Rate ◽  
Reduction Process ◽  
Kinetic Studies ◽  
Best Fitting ◽  
Industrial Use ◽  
Kinetics Of ◽  
Fitting Model ◽  
Potential Use

The extensive industrial use of the heavy metal molybdenum (Mo) has led to an emerging global pollution with its traces that can even be found in Antarctica. In response, a reduction process that transforms hexamolybdate (Mo6+) to a less toxic compound, Mo-blue, using microorganisms provides a sustainable remediation approach. The aim of this study was to investigate the reduction of Mo by a psychrotolerant Antarctic marine bacterium, Marinomonas sp. strain AQ5-A9. Mo reduction was optimised using One-Factor-At-a-Time (OFAT) and Response Surface Methodology (RSM). Subsequently, Mo reduction kinetics were further studied. OFAT results showed that maximum Mo reduction occurred in culture media conditions of pH 6.0 and 50 ppt salinity at 15 °C, with initial sucrose, nitrogen and molybdate concentrations of 2.0%, 3.0 g/L and 10 mM, respectively. Further optimization using RSM identified improved optimum conditions of pH 6.0 and 47 ppt salinity at 16 °C, with initial sucrose, nitrogen and molybdate concentrations of 1.8%, 2.25 g/L and 16 mM, respectively. Investigation of the kinetics of Mo reduction revealed Aiba as the best-fitting model. The calculated Aiba coefficient of maximum Mo reduction rate (µmax) was 0.067 h−1. The data obtained support the potential use of marine bacteria in the bioremediation of Mo.

Effect of low oxygen concentration on activation of inflammation by Helicobacter pylori

2021 ◽  
Vol 560 ◽  
pp. 179-185
Author(s):  
Adiza Abass ◽  
Tokuju Okano ◽  
Kotchakorn Boonyaleka ◽  
Ryo Kinoshita-Daitoku ◽  
Shoji Yamaoka ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Oxygen Concentration ◽  
Low Oxygen ◽  
Low Oxygen Concentration

The Constant Low Oxygen Concentration in All the Target Cells for Mouse Tail Radionecrosis

1982 ◽  
Vol 92 (1) ◽  
pp. 172 ◽  
Author(s):  
J. H. Hendry ◽  
J. V. Moore ◽  
B. W. Hodgson ◽  
J. P. Keene
Keyword(s):  
Oxygen Concentration ◽  
Target Cells ◽  
Low Oxygen ◽  
Low Oxygen Concentration

Polyelectrolyte–single wall carbon nanotube composite as an effective cathode catalyst for air-cathode microbial fuel cells

2014 ◽  
Vol 70 (10) ◽  
pp. 1610-1616 ◽  
Author(s):  
Huanan Wu ◽  
Min Lu ◽  
Lin Guo ◽  
Leonard Guan Hong Bay ◽  
Zheng Zhang ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Carbon Nanotube ◽  
Oxygen Reduction ◽  
Microbial Fuel Cells ◽  
Reduction Process ◽  
Air Cathode ◽  
Single Wall Carbon Nanotube ◽  
Single Wall Carbon ◽  
Cathode Catalysts ◽  
Metal Free

Polyelectrolyte–single wall carbon nanotube (SCNT) composites are prepared by a solution-based method and used as metal-free cathode catalysts for oxygen reduction reaction (ORR) in air-cathode microbial fuel cells (MFCs). In this study, two types of polyelectrolytes, polydiallyldimethylammonium chloride (PDDA) and poly[bis(2-chloroethyl)ether-alt-1,3-bis[3-(dimethylamino)propyl]urea] (PEPU) are applied to decorate the SCNTs and the resulting catalysts exhibit remarkable catalytic ability toward ORR in MFC applications. The enhanced catalytic ability could be attributed to the positively charged quaternary ammonium sites of polyelectrolytes, which increase the oxygen affinity of SCNTs and reduce activation energy in the oxygen reduction process. It is also found that PEPU–SCNT composite-based MFCs show efficient performance with maximum power density of 270.1 mW m−2, comparable to MFCs with the benchmark Pt/C catalyst (375.3 mW m−2), while PDDA–SCNT composite-based MFCs produce 188.9 mW m−2. These results indicate that PEPU–SCNT and PDDA–SCNT catalysts are promising candidates as metal-free cathode catalysts for ORR in MFCs and could facilitate MFC scaling up and commercialization.

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