| Abstract
| - Polychlorinated biphenyls (PCBs) are pollutants ofenvironmental concern due to their widespread presenceand persistence. The sonolytic destruction of aqueouspolychlorinated biphenyls (PCBs) is reported in this article.The kinetics and transformation pathways were investigatedat multiple frequencies and with various analyticaltools. The pseudo-first-order rate constants for 2-PCB (4.6μM), 4-PCB (5.4 μM), and 2,4,5-PCB (7.6 × 10-2 μM)were 2.1 × 10-3 ± 2.8 × 10 -5 s-1, 1.6 × 10-3 ± 3.4 ×10-5 s-1, and 2.6 × 10-3 ± 9.4 × 10 -5 s-1, respectively, whenAr-saturated solutions were sonicated at 20 kHz and anacoustic intensity of 30.8 W cm-2. Chlorine recovery aschloride ion was 77%, 79%, and 70% for 2-PCB, 4-PCB, and2,4,5-PCB under the same conditions. Electron spinresonance (ESR) experiments demonstrated that phenylradical was formed during sonolysis of 2-PCB and 4-PCB.The formation of biphenyl, which was detected by massspectroscopy, also indicates PCB dechlorination duringsonication. Ethyl benzene, diethylbiphenyl, dibutylbiphenyl,phenol, propylphenol, and di-tert-butyl phenol were alsodetected by mass spectroscopy as products of PCB sonication.The kinetics of 2-PCB composition as well as the role ofaqueous hydroxyl radical were examined at 20, 205, 358, 618,and 1071 kHz. The ultrasonic frequency significantlyimpacted the reaction rate and chloride recovery.
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