紫外辐射对水中三氯生降解  

Degradation of triclosan by UV irradiation in water

作　　者：史鸿乐 刘义青 付永胜 楚英豪[2] SHI Hongle1, LIU Yiqing1 , FU Yongsheng1, CHU Yinghao2(1. Faeulty of Geoseienees and Environmental Engineering, Southwest Jiaotong University, Chengdu 611756 2. College of Arehiteeture ＆ Environment, Siehuan University, Chengdu 61006)

机构地区：[1]西南交通大学地球科学与环境工程学院,成都611756 [2]四川大学建筑与环境学院,成都610065

出　　处：《环境科学学报》2018年第4期1521-1528,共8页Acta Scientiae Circumstantiae

基　　金：长江上游水与资源管理的可持续利用联合研究项目(No.2012DFG91520);成都市科技局项目(No.2014-HM01-00278-SF)~~

摘　　要：三氯生(TCS)作为一种新兴的污染物在不同环境介质中(如生活污水、地表水、地下水和底泥)不断被检出,其在环境中可抑制某些藻类的生长发育、干扰人体激素的分泌、诱发抗药性细菌的出现,对人体健康和生态系统造成不利影响.本研究调查了紫外辐射对水中TCS的降解;考察了p H、天然有机物(NOM)、硝酸盐(NO-3)和碳酸氢盐(HCO-3)对TCS去除的影响;探讨了TCS的光解产物和转化机理.结果表明:TCS在紫外光照下降解符合准一级反应动力学.随着p H的升高,TCS的摩尔吸光系数逐渐增大,其降解效率也逐渐提高.相比于质子化形态的TCS,去质子化的TCS更容易发生光降解.NOM的存在会抑制水中TCS的光解,且NOM浓度越高,抑制作用越明显,这主要是由于NOM能够与TCS竞争入射的紫外光子.NO-3在紫外光照下可以产生羟基自由基(HO·),其在水中的存在可以加快TCS的降解.与单独存在NO-3相比,NO-3和HCO-3的共存可以进一步促进TCS的去除,这可能归因于HCO-3和HO·反应生成的碳酸根自由基(CO·-3).利用液相色谱——超高解析度四级杆飞行时间串联质谱仪(LC-QTOF/MS)检测到7种TCS光解产物,基于这些鉴定的反应产物提出TCS的可能降解机理主要包括3种不同的反应路径,分别为脱氯氢化、脱氯羟基化和醌化反应.Triclosan（ TCS）,an emerging contaminant,has been detected frequently in different environmental compartments,such as sewage,surface water,ground water and sediment throughout the world in recent years. Its occurrence in natural environment may have adverse impacts on human health and ecosystem through the inhibition for the growth of alage,disruption of hormone secretion and the development of drug resistant bacteria. The degradation of TCS under UV irradiation was thus investigated in this study. The effect of p H,natural organic matter（ NOM）,nitrate（ NO3^-） and bicarbonate（ HCO3^-） on the removal of TCS was also evaluated. Finally,the degradation products and transformation mechanism of TCS by UV photolysis was studied. The results showed that the degradation of TCS under UV irradiation followed the pseudo first-order kinetics. The molar absorption coefficient of TCS increased with the increase of p H,leading to the enhancement of its degradation efficiency. The deprotonated TCS could be photolyzed more easily than the protonated TCS. Due to the competition for the incident UV photon between NOM and TCS,the presence of NOM could inhibit the photolysis of TCS and the inhibiting effect enhanced with the increase in the concentration of NOM. Hydroxyl radical（ HO·） could be generated through NO3^- under UV irradiation,resulting in the improvement of TCS degradation. Compared to the presence of NO3^- only,the coexist of NO3^- and HCO3^- could effectively enhance the removal of TCS because of the generation of carbonate radical（ CO·3^-） through the reaction of HCO3^- and HO·. Seven degradation products of TCS were detected using a ultra-high definition accurate-mass quadrupole time-of-flight tandem mass spectrometer coupled with a high performance liquid spectrometer（ LC-QTOF/MS）. Based on these identified reaction products,the possible degradation mechanism of TCS by UV photolysis was proposed showing three different transformation pathways,including dechlorination-hydrogenation,dechlo

关 键 词：三氯生 紫外光解 光敏剂 羟基自由基 降解产物 

分 类 号：X703[环境科学与工程—环境工程]