Search results

1

Coal Char Kinetics of Oxidation and Gasification Reactions

100%

Lewtak R., Hercog J.

Chemical and Process Engineering

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2017

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vol. 38

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issue 1

2

Synthesis and un-isotherm kinetic study of some ferrocene acids

100%

Apreutesei D., Lisa G., Hurduc N., Scutaru D.

Open Chemistry

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2004

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vol. 2

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issue 4

553-562

EN

The goal of this paper is to study thermal stability of some ferrocenes with acidic functional groups. Some other kinetic characteristics such as critical temperature and the rate constant corresponding to maximal degradation speed have been also evaluated. The type of functional units adjacent to the ferrocenyl unit determines thermal stability of ferrocene compounds. Groups with a powerful withdrawing effect determine a decreasing of the temperatures at which the material starts to lose weight. If a very long alkyl chain is connected to the ferrocene unit, a shielding effect in respect to the other carboxylic groups was observed, with an increase of the thermal stability.

3

A Numerical Approach to Predict Sulphur Dioxide Emissions During Switchgrass Combustion

100%

Peters B., Smuła-Ostaszewska J.

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vol. 34

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issue 1

121-137

EN

The demand for a net reduction of carbon dioxide and restrictions on energy efficiency make thermal conversion of biomass a very attractive alternative for energy production. However, sulphur dioxide emissions are of major environmental concern and may lead to an increased corrosion rate of boilers in the absence of sulfatation reactions. Therefore, the objective of the present study is to evaluate the kinetics of formation of sulphur dioxide during switchgrass combustion. Experimental data that records the combustion process and the emission formation versus time, carried out by the National Renewable Energy Institute in Colorado (US), was used to evaluate the kinetic data. The combustion of switchgrass is described sufficiently accurate by the Discrete Particle Method (DPM). It predicts all major processes such as heating-up, pyrolysis, combustion of switchgrass by solving the differential conservation equations for mass and energy. The formation reactions of sulphur dioxide are approximated by an Arrhenius-like expression including a pre-exponential factor and an activation energy. Thus, the results predicted by the Discrete Particle Method were compared to measurements and the kinetic parameters were subsequently corrected by the least square method until the deviation between measurements and predictions was minimised. The determined kinetic data yielded good agreement between experimental data and predictions.

4

STABILITY STUDIES OF CEFTIOFUR SODIUM IN AQUEOUS SOLUTIONS AND IN THE SOLID PHASE

100%

Dołhań A., Sobczak A., Muszalska I., Medenecka B., Garbacki P., Tomczak S., Jelińska A.

Acta Poloniae Pharmaceutica - Drug Research

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2018

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vol. 75

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issue 6

1279-1286

EN

Ceftiofur sodium (CFT), a third-generation cephalosporin for parenteral use, is commonly used in veterinary medicine against aerobic Gram-positive and Gram-negative bacteria as well as certain anaerobes. Its broad spectrum of activity and resistance to beta-lactamases result from the presence of methoxyimino and aminothiazole moieties at C-7 in the cephalosporin structure. The aim of this study was a comprehensive evaluation of the stability of CFT in the solid phase and in aqueous solutions. A fast and sensitive HPLC isocratic method was used for the determination of CFT degradation in the solid phase and in aqueous solutions. CFT degradation occurred according to a first-order reaction depending on the substrate concentration. The kinetic and thermodynamic parameters of CFT degradation in the solid phase were calculated. General acid-base hydrolysis of CFT was not observed in the solutions of hydrochloric acid, sodium hydroxide, phosphate (pH 5.84 – 7.25), acetate (pH 3.65 – 5.48) and borate (pH 7.49 – 10.07) buffers. CFT was the most stable in the pH range 2 – 6. The susceptibility of CFT to degradation under the influence of stress factors (pH, temperature, buffer components concentration, relative air humidity) should be considered in terms of storage conditions and the preparation of the product for administration.

5

A Numerical Approach to Predict Sulphur Dioxide Emissions During Switchgrass Combustion

88%

Peters B., Smuła-Ostaszewska J.

Chemical and Process Engineering

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2013

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issue 1

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1 Tomczak S.

Coal Char Kinetics of Oxidation and Gasification Reactions

Synthesis and un-isotherm kinetic study of some ferrocene acids

A Numerical Approach to Predict Sulphur Dioxide Emissions During Switchgrass Combustion

STABILITY STUDIES OF CEFTIOFUR SODIUM IN AQUEOUS SOLUTIONS AND IN THE SOLID PHASE

A Numerical Approach to Predict Sulphur Dioxide Emissions During Switchgrass Combustion