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There are indications that the conditions within the bubble
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In summary, aqueous PCBs rapidly decompose when
exposed to ultrasound. Both thermolysis and free radical
attack are important pathways of PCB destruction. Our
conclusions are based upon monitoring the concentration
of the parent compounds, identifying and measuring the
formation of phenyl radical, and characterizing organic
byproducts during sonolysis. Furthermore, we compare
chloride ion recoveries and PCB destruction kinetics over a
range of ultrasonic frequencies. Ultrasonic irradiation is
optimal at 358 kHz, but the chloride recovery is optimal at
1071 kHz. The differential role of aqueous •OH attack was
confirmed over a range of ultrasonic frequencies.
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The authors wish to thank the United States Department of
Energy (DOE Grant Number DE-FG07-96ER14710) and the
Purdue Research Foundation (Award Number 6902644) for
funding these studies. We also thank Dr. Carl Wood and
Connie Bonham at the Mass Spectrometry Service Center of
Purdue University for analysis of mass spectra and Dr.
Michael Everly of The Jonathan W. Amy Facility for Chemical
Instrumentation (JAFCI) at Purdue University for help with
the ESR experiments.
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Received for review November 2, 1998. Revised manuscript
received May 11, 1999. Accepted November 2, 1999.
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