【摘要】 为优化光降解法去除饮用水中的微囊藻毒素,分别用UVA(l=300~400nm)和UVC(l=253.7nm)2种紫外光源研究了紫外光波长对MC-RR降解效率的影响.结果表明,不同波段的紫外光具有不同的催化效率和降解中间产物.在UVA下照射12h后,MC-RR仍有30%~50%残余,同时产生2种几何异构体4(Z)-Adda-MC-RR和6(Z)-Adda-MC-RR,且二者在整个反应过程中保持恒定的比例.而在UVC下,MC-RR除生成2种异构体外,还生成中间产物[三环-Adda]MC-RR,在0.850mW/cm2光强下照射60min后,这些中间产物随MC-RR一起基本消失.两种情况下,MC-RR浓度随时间的变化均可用二级反应速率方程描述,表观反应速率常数(k)均随着光强度的增加而增大.尽管UVC强度仅为UVA的10%,但MC-RR在UVC下的反应速率常数却比UVA下高了近2个数量级.这表明,利用光降解技术去除饮水中的微囊藻毒素宜选用UVC光源.更多还原

【Abstract】 In order to optimize the technique of photodegradation for removing microcystins from drink water, the influence of UV wavelengths on the degradation efficiency of MC-RR was studied with two kinds of UV source, UVA (l=300~400nm) and UVC (l=253.7nm) respectively. Different UV wave band yielded different degradation efficiencies and intermediate products. After 12 hours of irradiation by UVA, there was still MC-RR residue of 30%~50%, meanwhile, two kinds of isomers 4(Z)-Adda-MC-RR and 6(Z)-Adda-MC-RR were produced, and their ratio kept constant during the whole process. At the irradiation of UVC, except these two isomers [Tricyclo-Adda]MC-RR was also found, and MC-RR as well as these intermediate products disappeared basically within 60 minutes at the irradiation intensity of 0.850mW/cm2. The change of MC-RR concentration with time under these two conditions could all be described with the second order reaction rate equation, showing the reaction rate constant increased with the enhancing of photo intensity. The rate reaction constant by UVC was two orders higher than that by UVA, even though UVC intensity was only 10% of UVA. These indicated that UVC source might be selected to use for application of photo degradation technique to remove microcystin from drink water.更多还原