Abstract
The effect of ultrasonic wave on degradation of an organic substance solution is investigated using the methylene blue as a modeling substance. The rate of decomposition of methylene blue is determined by measuring the change in light absorbance of the methylene blue solution. A great many cavitation hot spots can be evolved in the methylene blue solutions with various solvents. Experimental results indicate that the hydroxyl radical formed during the thermal decomposition of water molecule can decompose methylene blue due to its strong oxidizing action. The rate of decomposition is promoted in the case of the methylene blue solution with FeSO_4・7H_2O, in which Fe^<2+> ion acted as a catalyst. With respect to the effect of reactor conditions on the ultrasonic decomposition of organic substance, it was found that the differences of the materials and the shape have great influence on the decomposition rate of methylene blue. This is because resonance condition is changed, which in turn brings about the change of the temperature and the pressure achieved in the cavitation bubble and the incidence of acoustic cavitation. This fact suggests that the design of the resonance conditions in acoustic reactor is crucially important in the ultrasonic degradation of organic chemical substances.
