Study On Microwave Ultraviolet Lamp And Its Application In The Degradation Of Dyestuff Wastewater

Recently, people have paid more attention to photochemical technology in treating wastewater because its advantage, such as high efficient and degradation rate, cheap and practical use in treatment of organic pollutants. At present, the study of photochemical technology generally focuses on combination of oxidant, regeneration of catalyst and the optimization of treatment process. However, less report on the study of light sources. The light source is a very important part in the photochemical process. The structure, shape, excitation mode, area and strength of radiation and life are main factors influencing the effect of degradation. The light source also influence the the cost of investment and maintenance. This thesis investigates the characteristics of ultraviolet light generated from microwave energy and its use in the degradation of dye wastewater. The main parts of this thesis include:Analysis the characteristics of the microwave ultraviolet lamp(MWUVL)Using high sensitive photometer, some characteristics of MWUVL, including the spectral output, ignition time, re-ignition time, stabilization time and the temperature changes during the operation are investigated. The results show that the spectral distribution of the MWUVL is similar to middle-pressure mercury lamps. However, the largest output of the spectra band at 254nm is about 1.2 times to 500W conventional ultraviolet lamp (CUVL), and the intensities at 313nm and 365nm are less than those of CUVL. The ignition time, re-ignition time and stabilization time are 2.4s, 1.2s and 125s respectively, they are all shorter than those of CUVL. The optimum operation temperature 40oC gives maximum output of the radiation continuously. Studies on the relationship between the MWUVL parameters and its spectral characteristicsWith constant microwave frequency and power, the influence of the parameters of lamp, such as the argon pressure, the lamp volume and the quantity of mercury on the spectral characteristic of the lamp are investigated. The results show that the intensity of ultraviolet region and the UV ratio increases firstly, and then drops slowly when the Ar pressure increases. The radiation intensity in the UV region increases with the increase of mercury quantity or volume in the lamp, and the ratio of UV decreases slowly.Study on the degradation of two simulation dye wastewaters with MWUVLBy using an azo dye (reactive red X-3B) and an anthraquinone dye (reactive blue KN-R) as a model wastewater. The absorbance removal, pH and TOC were determined during photochemical reaction. The results show that in 110 min treatment time, the efficiency of absorbance and TOC removal of the reactive red X-3B dye were 96%and 66% respectively (initial concentration was 80mg/l). And those of the reactive blue KN-R were 73% and 33% respectively (initial concentration was 40mg/l). The degradation of MWUVL is far better than that of CUVL or microwave during the reaction.