P07 炭酸水素ナトリウム添加によるソノケミカル反応速度の増減(ポスターセッション)

抄録

Sonolysis of 0.1MKI-NaHCO_3 solution was carried out under Ar by an ultrasonic extraction apparatus (Honda Electronics UMS, 200 kHz and maximum power 15 W). The rate of sono-oxidation was evaluated by potassium iodide (KI) dosimetry at 355 nm using UV-Vis spectrophotometer (JASCO V-650). We had more rate below 1.5 mM NaHCO_3-KI solution compared with the KI solution without NaHCO_3. Over 1.5 mM solution of NaHCO_3, on the contrary, the rate fell down. Thus, sono-oxidation rate of I^- depended on concentration of NaHCO_3. We also observed multi-bubble sonoluminescence (MBSL) of NaHCO_3 solution. The intensity of MBSL fell down with concentration of NaHCO_3. Namely, cavitation intensity decreases in the presence of NaHCO_3 because NaHCO_3 reacts to CO_2 during sonication and the temperature in bubbles fall down by CO_2. The rate of sono-oxidation, however, increased in the solution with a small amount of NaHCO_3. It has been known that CO_2 quenches ^.H radicals, which are produced from solvent (H_2O). Remaining ^.OH radicals oxidize I^-. Therefore, NaHCO_3 in an aqueous solution could play the role of rate control of sono-oxidation under ultrasonic irradiation.