[Efficient Photolysis of Acid Orange 7 Using Low-frequency Electrodeless Lamp]

Using the low-frequency electrodeless lamp (LFEL) of 40 watts, the photodegradation of Acid orange 7 (A07) in water solution was studied. By applying a special reactor in which the light source was placed under the water, photodegradation efficiency of A07 using LFEL was compared with that using common UV mercury lamp. A few small degradation products were detected by GC-MS. The photodegradation mechanism of A07 was also studied based on the degraded compounds and the reactive oxidation species (ROS). It was found that the degradation rate of A07 could reach 94.1% under the conditions of aeration of 2 m3 x min(-1), AO7 20 mg x L(-1) of 7 L and 4 h reaction. The experimental results demonstrated that the degradation ability could be attributed to two aspects: the direct degradation and the indirect degradation of oxidation by ROS. Oxygen is an important source of ROS and providing more air could increase the degradation rate, and detectable ozone was produced when LFEL was working. Quenching tests showed that (1)O2 and O2*- were the key active species and *OH nearly had no function, which also indicated that the concentration of dissolved oxygen ( DO) was a key factor for the degradation.