平面型氙准分子灯特性及其在降解水相枣红中的应用

The Characteristics of the Planar Xe Excimer Lamp and its Applications in Degradation of Claret Dye in Water

研究了平面型氙准分子灯的真空紫外(VUV)辐射特性,电源电压、频率和充气压强对辐射强度和效率均有影响.研究表明在正弦电压驱动下,充气压3×104Pa左右时有最佳辐射强度和效率.在本实验中用于水处理实验的氙准分子灯参数为电压4kV,频率20kHz,气压3.8×104Pa,对应的辐射功率为25.4mW(光子流量2.2×10-6einstein·min-1).选用偶氮类染料枣红作为被分解物质,发现氙准分子灯的172nm辐射能够有效地使枣红解离,解离反应呈准一级反应,解离速率为9.28×10-8mol·min-1,光量子产额4.2×10-2mol·einstein-1.有机物初始浓度、溶液pH值、光强等都会对解离率产生影响.在氙准分子灯和反应溶液不直接接触时,发现解离率和COD(化学需氧量)去除率并不一直随着光强增加而增大,而有一最佳值.

The vacuum ultraviolet (VUV) characteristic of planar Xe excimer lamp is studied. It is found that VUV intensity and efficiency of the Xe excimer lamp studied depend on many parameters including applied voltage, frequency, and gas pressure as well. When the lamp is driven by sinusoidal voltage, the optimum filling pressure corresponding to the maximum VUV radiation intensity and efficiency is about 3×10~4 Pa. The optimized parameters of the lamp for water treatment are found to be: voltage 4 kV, frequency 20 kHz, pressure 3.8×10~4 Pa while the radiation power of the lamp is 25.4 mW (equal to photon flow of 2.2×10^(-6) einstein·min^(-1)). The VUV radiation has proven to be an effective method to degrade claret which is a representive azo dye. Observations show that the decolorization of claret is of pseudo-first-order kinetics. The rate of disappearance of claret is 9.28×10^(-8) mol·min^(-1) and the quantum yield is 4.2×10^(-2) mol·einstein^(-1). Many factors such as initial concentration of organic substrate, the pH of the solution and VUV internsity affect the decolorization rate. When a thin air layer exists between the surface of the lamp and water solution, the effciency of decolorization and COD removal do not increased linearly with the radiation intensity but are optimized at certain VUV intensity.