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Effect of ultrasound on chemical reactions
2001 (English)Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

The use of ultrasound to enhance chemical reactions is termed “sonochemistry”. The literature studied in this area prove that ultrasound can enhance chemical reaction rates in a variety of reaction systems. It can successfully increase the conversion, improve the yield, change the reaction pathway and/or initiate the reaction in biological, chemical and electrochemical systems. High-power ultrasound produces this effect via cavitating bubbles formed by the sound wave propagating through the media. Each cavitation bubble including its direct environment acts as a localised micro-reactor that, in aqueous systems, generates pressures of hundreds of atmospheres and temperatures of thousands of degrees when collapsed. Reactions with single electron transfer (SET) mechanisms are the ones most effected by ultrasound according to the literature. The collapse of a cavitating bubble is also found to help crystallisation by forming seed-crystals. This study was made in order to learn more about ultrasound, to find out if AstraZeneca can benefit in any way from the positive effect of ultrasound and what kind of large-scale equipment are available on the market today. The method for this study was to make screening experiments on three different reactions and select one of them for a more intense study. Of the three reactions studied only one reaction, a slurry-reaction, seemed to be affected by sonication so it was selected for further experiments. This reaction is not a SET mechanism, but sonication contributes with other effects like improved mass transport, removal of unreactive surface coatings from particles and crushing of agglomerates. For the selected slurry-reaction, it looks like larger reactive surface area and the way of crystallisation of formed product are the reasons for enhanced reaction rate.

Place, publisher, year, edition, pages
2001.
Keyword [en]
Technology, Chemistry, ultrasound, sonochemistry, sonication, kavitation, reaction rate
Keyword [sv]
Teknik
Identifiers
URN: urn:nbn:se:ltu:diva-50647ISRN: LTU-EX--01/257--SELocal ID: 7e291222-4f8a-4082-8a17-08298e6d5d66OAI: oai:DiVA.org:ltu-50647DiVA: diva2:1024009
Subject / course
Student thesis, at least 30 credits
Educational program
Chemical Engineering, master's level
Examiners
Note
Validerat; 20101217 (root)Available from: 2016-10-04 Created: 2016-10-04Bibliographically approved

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  • apa
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  • ieee
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  • de-DE
  • en-GB
  • en-US
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