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Abstract

The results of studies on the disintegration kinetics of the yeast Saccharomyces cerevisiae are presented. The process was carried out in a 500 W ultrasonic homogenizer equipped with a spherical working chamber with a volume of 100 cm 3. The concentration of the suspension of microorganisms was 0.05 g d.m./cm 3. The continuous phase was water solution containing 0.15 M NaCl and 4 mM K 2HPO 4. The kinetics of cell disruption were studied by the direct method. The theory of random transformation of dispersed matter was used to analyze the process. There was significant variation in the size of yeast cells. The range of changes in the values of parameters describing the size of microorganisms was divided into size classes. The kinetics of cell disruption in individual classes was described by a first-order linear differential equation. During the implosion of cavitation bubbles, the transformation volume of individual microorganisms is generated. It has been shown that as the volume of cells in subsequent size classes increases, their transformation volumes do not increase significantly. The safe volume for cells remains unchanged. As the size of the microorganisms increased, there was no increase in the constant rate of cell disruption.
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Authors and Affiliations

Anna Kacprowicz
1
ORCID: ORCID
Marek Solecki
1
ORCID: ORCID

  1. Lodz University of Technology, Faculty of Process and Environmental Engineering, Wolczanska 213, 93-005 Lodz, Poland
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Abstract

A catalytic combustion of organic admixtures of air belongs to the basic technologies of gas purification. A macrokinetics of admixtures combustion over the porous catalysts was described. The theoretical approach is in agreement with standard description of macrokinetics of the catalytic processes. The relationship between the fundamental magnitudes: observed process rate r*, reaction rate r in the kinetic zone, and a coefficient of the surface utilization η in the form r*= r · η have been described. These magnitudes combines the Thiele module φ. A kinetics equation for the isothermal and non-isothermal conditions was provided. The influence of mass and heat transfer in the catalyst grain on the course of the process was described by means of the surface utilization coefficient η. An equation describing this coefficient for both isothermal and non-isothermal conditions was given. The second part of this work concerns the application of theory. When the composition of purified gas is continuously varied, a quantitative approach is rather impossible. The theory was used for the qualitative analysis of process on the basis of the experimental results. A fulfillment of the first-order kinetics means that the degree of admixtures conversion does not depend on their initial concentrations. A non-isothermicity of the catalyst grain is expressed in such a way that the process rate observed over the large porous grains of the catalyst can be higher than the reaction rate in the kinetic zone. A temperature deference between the catalyst grains and flowing gas causes that the reactor can be stably operated at varied concentrations of admixtures and temperature over a relatively wide range. It was also demonstrated that the flammable admixtures may advantageously influence the conversion of hardly combustible admixtures

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Authors and Affiliations

Jerzy Straszko
Wiesław Parus
Wojciech Paterkowski

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