The Influence of oxygen concentration and of specific rate of growth on the kinetics of Penicillin production

1976 ◽  
Vol 18 (4) ◽  
pp. 493-512 ◽  
Author(s):  
A. R. Giona ◽  
R. De Santis ◽  
L. Marrelli ◽  
L. Toro
Keyword(s):  
Oxygen Concentration ◽  
Specific Rate ◽  
Penicillin Production ◽  
Rate Of Growth ◽  
Kinetics Of

Kinetics of synthesizing process for obtaining iron nanopowder by chemical-metallurgical method under isothermal conditions

2021 ◽  
pp. 72-77
Author(s):  
Tien Hiep Nguyen ◽  
◽  
Van Minh Nguyen ◽  
Keyword(s):  
Hydrogen Reduction ◽  
Average Particle Size ◽  
Chemical Deposition ◽  
Reduction Process ◽  
Nitrogen Adsorption ◽  
Specific Rate ◽  
Average Particle ◽  
Isothermal Conditions ◽  
Electron Microscopes ◽  
Kinetics Of

In this work the kinetics of synthesizing process of metallic iron nanopowder by hydrogen reduction from α-FeOOH hydroxide under isothermal conditions were studied. α-FeOOH nanopowder was prepared in advance by chemical deposition from aqueous solutions of iron nitrate Fe(NO3)3 (10 wt. %) and alkali NaOH (10 wt. %) at room temperature, pH = 11, under the condition of continuous stirring. The hydrogen reduction process of α-FeOOH nanopowder under isothermal conditions was carried out in a tube furnace in the temperature range from 390 to 470 °C. The study of the crystal structure and composition of the powders was performed by X-ray phase analysis. The specific surface area S of the samples was measured using BET method by low-temperature nitrogen adsorption. The average particle size D of powders was determined via the measured S value. The size characteristics and morphology of the particles were investigated by transmission and scanning electron microscopes. The calculation of the kinetic parameters of the hydrogen reduction process of α-FeOOH under isothermal conditions was carried out by the Gray-Weddington model and Arrhenius equation. It is shown that the rate constant of reduction at 470 °C is approximately 2.2 times higher than in the case at 390 °C. The effective activation energy of synthesizing process of iron nanopowder by hydrogen reduction from α-FeOOH was ~38 kJ/mol, which indicates a mixed reaction mode. In this case, the kinetics overall process is limited by both the kinetics of the chemical reaction and the kinetics of diffusion, respectively, an expedient way to accelerate the process by increasing the temperature or eliminate the diffusion layer of the reduction product by intensive mixing. It is show that Fe nanoparticles obtained by hydrogen reduction of its hydroxide at 410 °C, corresponding to the maximum specific rate of the reduction process, are mainly irregular in shape, evenly distributed, the size of which ranges from several dozens to 100 nm with an average value of 75 nm.

scholarly journals Influencing the growth kinetics of yeast strains with vitamin supplementation

2018 ◽  
pp. 113-115
Author(s):  
Judit Molnár ◽  
Erika Lakatos ◽  
Balázs Ásványi
Keyword(s):  
Corn Steep Liquor ◽  
Cell Mass ◽  
Single Cell Protein ◽  
Vitamin Supplementation ◽  
Cell Protein ◽  
Specific Rate ◽  
Yeast Strains ◽  
Matter Production ◽  
Steep Liquor ◽  
Kinetics Of

The aim of the current experiment was to optimize the creation process of single cell protein on plant-based substrate solution with the intention to improve end-product turn out by means of adding vitamin solution. Based on the results of the fermentation processes of yeast strains, it was concluded that the vitamin-supplementation produced its greatest effect on the dry matter production, primarily on the K. marxianus DSM 4908 strain, while it was less beneficent when it comes to the figures of wet cell mass. In addition, it can be assumed that vitamin supplementation increased the maximum specific rate of growth (μmax) and decreased the generation time (tg) significantly. In the case of the K. marxianus yeast strain on corn steep liquor treated with vitamin-supplementation, the highest (μmax) and the lowest (tg) data were observed [(0.226 h-1) and (4.4 h), respectively]. Based on the results it was found that K. marxianus DSM 4908 is expedient to be applied on corn steep liquor medium in order to determine its suitability to produce additive for feeding.

Kinetics of the Reaction Between S2O3-- and I3- in Aqueous Solution

1974 ◽  
Vol 29 (1) ◽  
pp. 141-144
Author(s):  
T. S. Rao ◽  
S. I. Mali
Keyword(s):  
Aqueous Solution ◽  
Reduction Potential ◽  
Frequency Factor ◽  
Effective Concentration ◽  
Specific Rate ◽  
Platinum Foil ◽  
First Order ◽  
Entropy Of Activation ◽  
Kinetics Of ◽  
Foil Electrode

The kinetics of the reaction between has been studied under conditions of production of iodine at a known rate by the persulfate-iodide reaction and its consumption by S2O3-- . The effective concentration of iodine during the steady state is measured from its reduction potential at a bright platinum foil electrode. The reaction is of first order with respect to I3- and S2O3-- individually and hence of over all second order. The specific rate is 1.51 X 105 M -1 sec-1 and the frequency factor is 1.69 × 1012 M -1 sec-1 at 25 °C. The energy of activation for the reaction is 9.58 × 103 cal/mole and the entropy of activation is -2.55 cal/mole deg.

The Role of Starting Potential in the Kinetics of Chemical Reactions under Electrodeless Discharge

1970 ◽  
Vol 25 (11) ◽  
pp. 1772
Author(s):  
T.S.R Ao ◽  
A. Patil
Keyword(s):  
Gas Phase ◽  
Chemical Reactions ◽  
Electric Discharge ◽  
Specific Rate ◽  
Gas Phase Reactions ◽  
Electrodeless Discharge ◽  
First Order ◽  
Kinetics Of

Abstract It has been shown that in kinetically first order gas phase reactions occuring under electric discharge, such as the decomposition of N2O, the application, at various initial pressures, of the same multiple of the respective starting potential ensures that the reaction occurs at the same specific rate.

A Raman Spectral Study of the Kinetics of Hydrolysis of Acetonitrile Catalyzed by Hg(II)

1975 ◽  
Vol 53 (3) ◽  
pp. 427-436 ◽  
Author(s):  
Yu-Keung Sze ◽  
Donald E. Irish
Keyword(s):  
Time Span ◽  
Water Molecules ◽  
Specific Rate ◽  
Ammine Complexes ◽  
Kinetics Of Hydrolysis ◽  
Specific Rate Constant ◽  
Rate Of Hydrolysis ◽  
Raman Spectral ◽  
Kinetics Of ◽  
Hydrolysis Of

Raman spectroscopy has been employed to follow the relatively slow rate of hydrolysis of acetonitrile, catalyzed by mercury(II). Raman lines at 2275 and 2305 cm−1 are characteristic of CH3CN bound to Hg2+, and are distinct from lines of bulk solvent. The intensities of these new lines decrease with time. From the intensities, concentrations of bound acetonitrile, [CH3CN]B were calculated for a time span of 400 min. The data fit a second order rate law: Rate = k[CH3CN]B[H2O]. The specific rate constant, k, obtained from four sets of data for the system Hg(ClO4)2–CH3CN–H2O equals 1.05 ± 0.06 × 10−4 mol−1 1 min−1 at 25 °C. The energy of activation is 18.9 kcal mol−1. In the proposed mechanism water molecules attack acetonitrile molecules which are bound to Hg2+ and form a mercury(II)–acetamide complex. Raman lines characteristic of this species are observed. This species slowly converts to mercury(II) ammine complexes and acetic acid. Anions which coordinate with Hg2+ more strongly than CH3CN, such as nitrate or acetate, slow or prevent the hydrolysis reaction.

scholarly journals The investigation of the kinetics of hydrochemical oxidation of metal sulphides with the aim of determination of the optimal conditions for the selective extraction of molybdenum from ores

2005 ◽  
Vol 41 (1) ◽  
pp. 33-45 ◽  
Author(s):  
V. Lutsik ◽  
A. Sobolev
Keyword(s):  
Rotation Frequency ◽  
Rotating Disk ◽  
Selective Extraction ◽  
Solution Temperature ◽  
Specific Rate ◽  
Disk Rotation ◽  
Diffusion Controlled ◽  
Kinetics Of Dissolution ◽  
Kinetics Of

The kinetics of the oxidation of molybdenyte, pyrite and sphalerite in solutions of nitric acid, hydrogen peroxide, and sodium hypochlorite was studied by the rotating disk method. The influence of the molar concentration of reagent, pH of solution, temperature, disk rotation frequency, and duration of measurements on the specific rate of hydrochemical oxidation of sulpfides was determined. The kinetic models allowing to calculate the dissolution rate of sulphides when these parameters change simultaneously were obtained. The conditions of kinetically and diffusion-controlled processes were detected. The details of mechanism of the studied processes were revealed. The nature of intermediate solid products, the reasons and the conditions of their formation as well as the character of their influence on the kinetics of dissolution processes were determined. The probable schemes of interactions corresponding to the observable kinetic dependences were offered. The conditions of the effective and selective molybdenum leaching directly from ore without its concentration were found.

Kinetics of the Rapid Reaction Cl2 + 2Br- → Br2 + 2Cl- in Aqueous Solution

1978 ◽  
Vol 33 (3) ◽  
pp. 391-392 ◽  
Author(s):  
T. S. Rao ◽  
S. I. Mali ◽  
V. T. Dangat
Keyword(s):  
Aqueous Solution ◽  
Energy Of Activation ◽  
Specific Rate ◽  
Rapid Reaction ◽  
Kinetics Of

AbstractA competition technique has been employed to study the kinetics of the rapid reaction Cl2+2Br- → Br2+ 2Cl- in aqueous solution. The specific rate at 25 °C and the energy of activation for the reaction are found to be 88.8 M-1s-1 and 71.1 kj mole-1, respectively.

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