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Ultrasound induced cavitation and sonochemical effects

IP.com Disclosure Number: IPCOM000128115D
Original Publication Date: 1999-Dec-31
Included in the Prior Art Database: 2005-Sep-14
Document File: 7 page(s) / 25K

Publishing Venue

Software Patent Institute

Related People

Gong, Cuiling: AUTHOR [+3]

Related Documents

http://theses.mit.edu:80/Dienst/UI/2.0/Describe/0018.mit.theses/1999-79: URL

Abstract

The introduction of a strong acoustic field to an aqueous solution results in the generation of cavitation microbubbles. The non-linear motion of these microbubbles focuses energy from the macro-scale acoustic waves to the micro-scale vapor inside the bubbles. As a result, extremely high localized pressures on the order of hundreds of atmospheres and temperatures on the order of thousands of degrees Kelvin are generated. Under such extreme conditions molecular dissociation occurs and produces highly reactive free radicals. This phenomenon provides a means of "; burning "; substances in liquids and enhancing reactions that cannot be achieved by conventional means. Sonochemistry, the chemistry associated with this phenomenon, has found application in drug delivery, waste decomposition, water treatment, chemical reaction enhancement and numerous novel material processes. A theoretical framework that directly couples the dynamics of bubble motion and the associated kinetics of gas phase reactions is established for the first time in an attempt to understand the fundamental mechanisms of the sonochemical phenomenon. Several fundamental mechanisms, which are believed to be critical in understanding the unusual experimentally observed sonoluminescence and sonochemical behavior, are revealed. First, not all chemical reactions associated with bubble oscillation in a sound field have reached thermodynamic equilibrium. Second, chemical kinetics couples closely with the bubble motion and has significant impact on the dynamics of bubble motion when a bubble contains a combustible gas mixture. Third, the dissolved gases affect the activities of a sonochemical event through both thermal effect by changing the peak collapse temperatures in the bubble and chemical effect by directly participating in reactions. In addition, a laboratory scale sonochemical experiment is conducted to demonstrate the sonochemical effects as a result of ultrasonic irradiation in a Fricke solution. Effects of the dissolved gases on sonochemical activities are experimentally quantified and compared with the predicted results using the model developed in this thesis. Thesis Supervisor: Douglas P. Hart Title: Associate Professor [2]

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 This record is the front matter from a document that appears on a server at MIT and is used through permission from MIT. See http://theses.mit.edu:80/Dienst/UI/2.0/Describe/0018.mit.theses/1999-79 for copyright details and for the full document in image form.

Ultrasound Induced Cavitation and Sonochemical Effects

by

Culling Gong
B.S., Tsinghua University (1990) M.S., University of Minnesota (1993) Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology February 1999
SIGNATURE OF author: [[signature omitted]]

Department of Mechanical Engineering

January 8, 1999

CERTIFIED BY: [[SIGNATURE OMITTED]]

Douglas P. Hart

Associate Professor Thesis Supervisor

ACCEPTED BY: [[SIGNATURE OMITTED]]

Ain A. Sonin Chairman, Department Committee on Graduate Students ARCHIVES MASSACHUSETTS INSTITUTE OF TECHNOLOGY LIBRARIES JUL 12 1999

Massachusetts Institute of Technology Page 1 Dec 31, 1999

Page 2 of 7

Ultrasound induced cavitation and sonochemical effects

Ultrasound Induced Cavitation and Sonochemical Effects

by Cuiling Gong

Submitted to the Department of Mechanical Engineering on January 8, 1999, in partial fulfillment of the requirements for the degree of Doctor of Philosophy

Abstract

The introduction of a strong acoustic field to an aqueous solution results in the generation of cavitation microbubbles. The non-linear motion of these microbubbles focuses energy from the macro-scale acoustic waves to the micro-scale vapor inside the bubbles. As a result, extremely high localized pressures on the order of hundreds of atmospheres and temperatures on the order of thousands of degrees Kelvin are generated. Under such extreme conditions molecular dissociation occurs and produces highly reactive free radicals. This phenomenon provides a means of " burning " substances in liquids and enhancing reactions that cannot be achieved by conventional means. Sonochemistry, the chemistry associated with this phenomenon, has found application in drug delivery, waste decomposition, water treatment, chemical reaction enhancement and numerous novel material processes.

A theoretical framework that directly couples the dynamics of bubble motion and the associated kinetics of gas phase reactions is established for the first time in an attempt to understand the fundamental mechanisms of the sonochemical phenomenon. Several fundamental mechanisms, which are believed to be critical in understanding the unusual experimentally observed sonoluminescence and sonochemical behavior, are revealed. First, not all chemical reactions associated with bubble oscillation in a sound field have reached thermodynamic equilibrium. Second, chemical kinetics couples closely with the bubble motion and has significant impact on the dynamics of bubble motion when a bubble contains a combustible gas mixture. Third, the dissolved gases affect the activities of a sonochemical event through both thermal effect by changin...