Combined sonochemical and short-wavelength UV degradation of hydrophobic perfluorinated compounds.

Perfluorochemicals (PFCs), which are common in the aquatic environment, are toxic substances that have high chemical and heat resistance because of their strong C-F bonds. We investigated the effect of ultrasonication and short-wavelength UV irradiation on the degradation of perfluorooctane, perfluoropropionic acid, and perfluorooctanoic acid, which are examples of hydrophobic, hydrophilic, and intermediate PFCs, respectively. The results confirmed that ultrasonication was more effective for decomposing hydrophobic PFCs and UV irradiation was more effective for decomposing hydrophilic PFCs.

Effect of ultrasonic frequency on size distributions of nanosized mist generated by ultrasonic atomization.

Ultrasonic atomization is used to produce fine liquid mists with diameter ranges below 100nm. We investigated the effect of the frequency on the size distribution of ultrasonic mist. A bimodal distribution was obtained for the mist generated by ultrasonic atomization with a wide-range particle spectrometer.