抄録
Combined or synergetic effect of titania photocatalysis and ultrasonication has been studied in recent. Most typical system for the combination is composed of the titania particles suspended in aqueous medium and 20-200 kHz ultrasound of general use. In this work, we employed fibrous titania prepared by a sol-gel coating on a metal fiber and high frequency ultrasound driven at 2.4 MHz and investigated the sono-photo synergetic effect using KI iodometry. It was found that the continuous bubbling through the sonication is quite effective in enhancing the KI index only at 2.4 MHz. One supporting data for this is that the degassing from water during the 2.4 MHz sonication was much more that that of the 200 kHz's or still standing. In addition, availability of the MHz sonication was conspicuous in the Ar/O_2 mixture. It can be inferred that oxygen-related active species whose lifetime are short for 200 kHz but is long for 2.4 MHz play an important role in the system. In the presence of titania fiber, the synergy index was found to be high compared to the other process. However, a large volume of the fiber in the solution may inhibit the propagation of ultrasound so far.
