低频无极灯降解偶氮染料酸性橙7

以40 W的新型低频感应无极灯(LFEL)作为反应光源,研究了其对于水中难生化降解偶氮染料酸性橙7(AO7)的降解效果.通过专用浸没式反应器研究了这种新型光源降解AO7的有效实验参数,并与传统汞灯光源做了降解AO7的实验对比,用GC-MS检测了主要降解产物小分子,探讨了LEEL对AO7的降解机制及反应活性物质(ROS).结果表明,LFEL对于水中的AO7染料具有较好的降解效果和较高的矿化率,在浸没式反应器中曝气量2 m3·min-1,AO7浓度为20 mg·L-1(7 L)在4 h的反应后能达到94.1%的降解率,而其降解能耗远低于传统汞灯光源.降解贡献来自于两个方面:直接吸收降解和间接通过活性物质(ROS)氧化作用.氧气是ROS的重要来源,加大曝气量会提高降解效率,反应过程中有臭氧的生成.添加淬灭剂显示,·OH对降解反应几乎无贡献,1O2和O2·-则是反应的主要活性物质.

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 (AO7)in water solution was studied. By applying a special reactor in which the light source was placed under the water, photodegradation efficiency of AO7 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 AO7 was also studied based on the degraded compounds and the reactive oxidation species (ROS). It was found that the degradation rate of AO7 could reach 94.1% under the conditions of aeration of 2 m³·min^-1, AO7 20 mg·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 ¹O₂ 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.