scholarly journals Oxidation of glucose and arabinose mixtures over Au/Al2O3

2020 ◽  
Author(s):  
Sebastian Franz ◽  
Nataliya D. Shcherban ◽  
Irina L. Simakova ◽  
Markus Peurla ◽  
Kari Eränen ◽  
...  
Keyword(s):  
Experimental Data ◽  
Kinetic Model ◽  
Partial Pressure ◽  
Catalytic Oxidation ◽  
Batch Reactor ◽  
Oxidation Reactions ◽  
Partial Pressure Of Oxygen ◽  
Oxidation Of Glucose

Abstract Oxidation of a mixture of glucose and arabinose over 1% Au deposited on alumina was investigated in a semi-batch reactor varying pH, temperature and partial pressure of oxygen. Elevation of the latter enhancing the rate induced also losses in selectivity to aldonic acids. A kinetic model representing the catalytic oxidation reactions of arabinose and glucose along with respective isomerization to fructose and ribulose was developed. Calculations based on the model were able to describe experimental data in a reliable way.

Leaching Behaviour of Metals from a Sphalerite Concentrate in Sulfuric Acid-Oxygen System

2011 ◽  
Vol 201-203 ◽  
pp. 1725-1731
Author(s):  
Cun Xiong Li ◽  
Chang Wei ◽  
Hong Sheng Xu ◽  
Ji Qiang Liao ◽  
Zhi Gan Deng ◽  
...  
Keyword(s):  
Experimental Data ◽  
Particle Size ◽  
Sulfuric Acid ◽  
Partial Pressure ◽  
Elemental Sulphur ◽  
Partial Pressure Of Oxygen ◽  
Mineralogical Analysis ◽  
Oxygen System ◽  
Copper Indium ◽  
Leaching Behaviour

Leaching behaviors of zinc, copper, indium and iron from a sphalerite concentrate in sulfuric acid-oxygen system has been investigated in the present paper. Various parameters were studied including particle size, concentration of sulfuric acid, partial pressure of oxygen, leaching temperature, and leaching time. The experimental data indicated that under the typical plant conditions employed up to 99% zinc , 85% copper and 90% indium extraction were achieved. The mineralogical analysis of the residue showed that the main minerals are elemental sulphur, unreacted pyrite and quartz, the amount of sulphide sulphur oxidized to sulfur during leaching is 81%. This process provides an effective way for the extraction of zinc, copper and indium from sphalerite concentrate.

scholarly journals Uptake of divalent manganese from aqueous solution using cation exchange resins

2016 ◽  
Vol 12 (4) ◽  
pp. 4312-4323
Author(s):  
Ayman Abdallah Ahmed
Keyword(s):  
Experimental Data ◽  
Aqueous Solution ◽  
Kinetic Model ◽  
Cation Exchange ◽  
Batch Reactor ◽  
Kinetic Equations ◽  
Correlation Coefficients ◽  
Manganese Removal ◽  
Cation Exchange Resins ◽  
Exchange Resins

The present work deals with the removal of highly toxic manganese ion from aqueous solution using cation exchange resins namely, Amberjet 1500H, Amberjet 1300H and Amberlite IRC86. The study was carried out in media of various ionic strengths (1.98-9.98 mmol/L), different resin dose (0.25-8.0 gm) and a wide solution acidity range (0.001-1.0 M), in addition to at three temperatures (293-318 K).The aim of this study was to understand the mechanisms that govern manganese removal and find a suitable equilibrium isotherm and kinetic model for the manganese removal in a batch reactor. The experimental isotherm data were analyzed using the Langmuir, Freundlich, Temkin and Dubinin–Radushkevich (D–R) equations. The experimental data were analyzed using four adsorption kinetic models – the pseudo first- and second-order, intraparticle diffusion and the Elovich equations – to determine the best fit equation for the adsorption of manganese ions onto the resins. The rate constants, equilibrium capacities and related correlation coefficients for each kinetic model were calculated and discussed. Also, predicted qt values from the kinetic equations were compared with the experimental data. Thermodynamic parameters, involving ΔH, ΔS and ΔG were also calculated from graphical interpretation of the experimental data

scholarly journals Calculation of the optical transmittance in cadmium oxide by considering oxygen plasma

2018 ◽  
Vol 39 (1) ◽  
pp. 65-74
Author(s):  
M. A. Grado-Caffaro ◽  
M. Grado-Caffaro
Keyword(s):  
Experimental Data ◽  
Partial Pressure ◽  
Cadmium Oxide ◽  
Detailed Comparison ◽  
Optical Transmittance ◽  
Deposition Process ◽  
Visible Range ◽  
Experimental Measurements ◽  
Partial Pressure Of Oxygen ◽  
Physical Quantities

Abstract By considering the partial pressure of oxygen in the deposition process of cadmium oxide, we calculate the maximum transmittance of cadmium oxide in the visible range, which is achieved at the so-called optimum partial pressure of oxygen, this value of pressure being a key figure of merit. Our formulation agrees with experimental measurements and is consistent with the so-called plasma-optical effect. At this point, an exhaustive evaluation of previous experimental data is performed by doing a detailed comparison among the results from different authors and by performing numerical estimations (including estimations from experimental data) of relevant physical quantities. In fact, a comprehensive discussion relative to comparison between experimental measurements and our theoretical results is presented.

Interaction of H2O, O2 and H2 with Proton Conducting Oxides Based on Lanthanum Scandates

2019 ◽  
pp. 88-100
Author(s):  
A. S. Farlenkov ◽  
N. A. Zhuravlev ◽  
Т. A. Denisova ◽  
М. V. Ananyev
Keyword(s):  
Water Vapor ◽  
Partial Pressure ◽  
Gas Phase ◽  
Molecular Hydrogen ◽  
Proton Magnetic Resonance ◽  
Partial Pressure Of Oxygen ◽  
Proton Conducting ◽  
Conducting Oxides ◽  
Temperature Range ◽  
Apparent Level

The research uses the method of high-temperature thermogravimetric analysis to study the processes of interaction of the gas phase in the temperature range 300–950 °C in the partial pressure ranges of oxygen 8.1–50.7 kPa, water 6.1–24.3 kPa and hydrogen 4.1 kPa with La1–xSrxScO3–α oxides (x = 0; 0.04; 0.09). In the case of an increase in the partial pressure of water vapor at a constant partial pressure of oxygen (or hydrogen) in the gas phase, the apparent level of saturation of protons is shown to increase. An increase in the apparent level of saturation of protons of the sample also occurs with an increase in the partial pressure of oxygen at a constant partial pressure of water vapor in the gas phase. The paper discusses the causes of the observed processes. The research uses the hydrogen isotope exchange method with the equilibration of the isotope composition of the gas phase to study the incorporation of hydrogen into the structure of proton-conducting oxides based on strontium-doped lanthanum scandates. The concentrations of protons and deuterons were determined in the temperature range of 300–800 °C and a hydrogen pressure of 0.2 kPa for La0.91Sr0.09ScO3–α oxide. The paper discusses the role of oxygen vacancies in the process of incorporation of protons and deuterons from the atmosphere of molecular hydrogen into the structure of the proton conducting oxides La1–xSrxScO3–α (x = 0; 0.04; 0.09). The proton magnetic resonance method was used to study the local structure in the temperature range 23–110 °C at a rotation speed of 10 kHz (MAS) for La0.96Sr0.04ScO3–α oxide after thermogravimetric measurements in an atmosphere containing water vapor, and after exposures in molecular hydrogen atmosphere. The existence of proton defects incorporated into the volume of the investigated proton oxide from both the atmosphere containing water and the atmosphere containing molecular hydrogen is unambiguously shown. The paper considers the effect of the contributions of the volume and surface of La0.96Sr0.04ScO3–α oxide on the shape of the proton magnetic resonance spectra.

Achieving Procedure of a Kinetic Model to Predict the Influence of the Process Global Temperature on a Technological Alcoholic Fermentation II. An Arrhenius type Kinetic Model

2008 ◽  
Vol 59 (4) ◽  
Author(s):  
Neculai Catalin Lungu ◽  
Maria Alexandroaei
Keyword(s):  
Experimental Data ◽  
Saccharomyces Cerevisiae ◽  
Kinetic Model ◽  
Economic Efficiency ◽  
Fermentation Process ◽  
Alcoholic Fermentation ◽  
Global Temperature ◽  
Medium Temperature ◽  
Biotechnological Process

The aim of the present work is to offer a practical methodology to realise an Arrhenius type kinetic model for a biotechnological process of alcoholic fermentation based on the Saccharomyces cerevisiae yeast. Using the experimental data we can correlate the medium temperature of fermentation with the time needed for a fermentation process under imposed conditions of economic efficiency.

Diffusion model for deposition of epitaxial GaAs layers prepared by the MOCVD method

1991 ◽  
Vol 56 (10) ◽  
pp. 2020-2029
Author(s):  
Jindřich Leitner ◽  
Petr Voňka ◽  
Josef Stejskal ◽  
Přemysl Klíma ◽  
Rudolf Hladina
Keyword(s):  
Experimental Data ◽  
Growth Rate ◽  
Kinetic Model ◽  
Gas Phase ◽  
Substrate Surface ◽  
Deposition Process ◽  
Hydrogen Atmosphere ◽  
Epitaxial Gaas ◽  
Kinetics Of ◽  
Good Agreement

The authors proposed and treated quantitatively a kinetic model for deposition of epitaxial GaAs layers prepared by reaction of trimethylgallium with arsine in hydrogen atmosphere. The transport of gallium to the surface of the substrate is considered as the controlling process. The influence of the rate of chemical reactions in the gas phase and on the substrate surface on the kinetics of the deposition process is neglected. The calculated dependence of the growth rate of the layers on the conditions of the deposition is in a good agreement with experimental data in the temperature range from 600 to 800°C.

Biorhythm of the partial pressure of oxygen in uterine and fetal tissues

1981 ◽  
Vol 92 (4) ◽  
pp. 1305-1307
Author(s):  
A. Ya. Chizhov ◽  
V. G. Filimonov ◽  
Yu. M. Karash ◽  
R. B. Strelkov
Keyword(s):  
Partial Pressure ◽  
Partial Pressure Of Oxygen ◽  
Fetal Tissues

Gas phase interaction with catalytic oxidation reactions

1972 ◽  
Vol 326 (1565) ◽  
pp. 215-227 ◽  
Keyword(s):  
Carbon Dioxide ◽  
Maleic Anhydride ◽  
Catalytic Oxidation ◽  
Gas Phase ◽  
Major Part ◽  
Oxidation Reactions ◽  
Mixed Gas ◽  
Kinetics Of ◽  
Oxidation Of Benzene ◽  
Homogeneous Decomposition

Studies of the catalytic oxidation of benzene to maleic anhydride and carbon dioxide over vanadia/molybdena catalysts show that the major part of the reaction involves interacting gas and gas-solid processes. The results are consistent with a mechanism in which a benzeneoxygen adduct is formed catalytically, desorbs and then reacts to give maleic anhydride entirely in the gas phase. On the basis of this proposed mechanism, the kinetics of individual reactions have been investigated in some depth. The over-oxidation of maleic anhydride has been found to be not significant under the conditions of reaction. The kinetic relationships governing the homogeneous decomposition of the adduct and the oxidation of the adduct to maleic anhydride and to carbon dioxide have been established. The results show that essentially all of the anhydride originates from mixed gas-solid/gas reaction while substantial amounts of carbon dioxide are produced entirely catalytically.

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