抄録
In the present study, the effects of pressure (gauge pressure), temperature and frequency on sonochemical reaction were investigated using a flow-type sonochemical reactor equipped with PZT transducers which effectively oscillate at the frequencies of 500kHz, 1MHz and 1.6MHz. Potassium iodide dosimetry was used in order to evaluate the effects of the pressure, temperature and frequency on the sonochemical reaction rate constant(k_e) per unit the ultrasound power estimated by calorimetry (P_<us>[W]). At the frequency of 500kHz, the k_e/P_<US> decreased with an increase in the pressure under the constant temperature condition of 293, 313 or 333 K and no KI oxidation reaction proceeded at the pressures of more than 0.1MPa, probably due to partially suppression of the formation/growth of cavitation bubbles which are seeds required to form hotspots. At 353 and 373 K, on the other hand, the k_e/P_<US> increased with the pressure until reaching weakly peaks at 0.05 and 0.2MPa, respectively. It appears that, since vapor pressure of water solvent is higher at the higher temperature, cavitation bubbles are moderately formed even under higher gauge pressure conditions and chemical effect is induced via explosive collapse of the bubbles. At the frequencies of 1 and 1.6MHz, the k_e/P_<US> increased with the pressure until reaching its maximum value under the constant temperature condition of 313, 333, 353 or 373K. In the cases of 1.6 and 1MHz as compared with 500kHz under the same temperature condition, the k_e/P_<US> reached its maximum value at the higher pressure. In the present work, the highest k_e/P_<US> value was obtained under the operating condition of 0.1MPa, 333K and 1.6MHz.
