高级氧化处理程序对除草剂丁基拉草及乐灭草之降解.docVIP

高級氧化處理程序對除草劑丁基拉草及樂滅草之降解 Photodegradation of Herbicides Butachlor and Oxadiazon Using Advanced Oxidation Processes 研究生: 劉碧松 Bisong Liu 指導教授: 林耀堅 Yaw-Jian Lin [摘要]In the past few decades, there is significant increase of pesticide usage to support the increasing demand of food production in Taiwan. Butachlor and oxadiazon are the most widely used herbicides in Taiwan. Due to their relatively high stability and retardation factors, butachlor and oxadiazon were persistent environmental pollutants in waters. The treatment of organic contaminants such as pesticides through photodegradation is a valuable technique. Butachlor and oxadiazon samples in water were treated using direct photodegradation, TiO2 photocatalysis and photo-Fenton. The experimental factors include pesticide concentrations, reaction vessles, different light sources, exposure time, H2O2 and Fe2+ concentrations and pH on the degradation of butachlor and oxadiazon. Degradation rates, rate constant, half lives, degree of mineralization and toxicity have been studied. The degradation rates had been increased with the increase of pesticide concentrations. Using quartz vessels and UV can efficiently degrade butachlor and oxadiazon. Photo-Fenton is the best method to degrade butachlor and oxadiazon. The toxicity of samples on the direct and indirect photodegradation showed only slightly difference with the increase of exposure time. In the mineralization of butachlor and oxadiazon, with the exposure time increased, total organic carbon TOC were decreased on the direct and TiO2 photodegradation of samples. In the photo-Fenton system, TOC were increased with the increase of exposure time that may be caused by unstable by-products. On the direct and TiO2 photodegradation, Cl- concentrations had been increased with exposure time. This indicated that dechlorination is the degradation route of butachlor and oxadiazon. Keywords：Butachlor Oxadiazon Advanced Oxadiazon Processes AOPs TiO2 photocatalysis photo-Fento