Photodegradation kinetics of iopamidol by UV irradiation and enhanced formation of iodinated disinfection by-products in sequential oxidation processes.
The photochemical degradation of iopamidol with low-pressure UV lamps and the formation of iodinated disinfection by-products (I-DBPs) during sequential oxidation processes including chlorine, monochloramine and chlorine dioxide were investigated in this study. Iopamidol can be effectively decomposed by UV irradiation with pseudo-first order reaction kinetics. The evaluated quantum yield was found to be 0.03318 mol einstein(-1). Results showed that iopamidol degradation rate was significantly increased by higher UV intensity and lower initial iopamidol concentration. However, the effect of solution pH was negligible. Degradation of iopamidol by UV photolysis was subjected to deiodination and hydroxylation mechanisms. The main degradation products including -OH substitutes and iodide were identified by UPLC-ESI-MS and UPLC-UV, respectively. Increasing the intensity of UV irradiation promoted the release of iodide. Destruction pathways of iopamidol photolysis were proposed. Enhanced formation of I-DBPs were observed after iopamidol photolysis followed by disinfection processes including chlorine, monochloramine and chlorine dioxide. With the increase of UV fluence, I-DBPs formation were significantly promoted.
State Key Laboratory of Pollution Control and Resources Reuse, Key Laboratory of Yangtze Aquatic Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China.
Fu-Xiang
FX
Tian
State Key Laboratory of Pollution Control and Resources Reuse, Key Laboratory of Yangtze Aquatic Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China. Electronic address: tjwenwu@gmail.com.
Bin
B
Xu
Department of Safety, Health and Environmental Engineering, National Kaohsiung First University of Science and Technology, Kaohsiung 824, Taiwan, ROC.
Yi-Li
YL
Lin
College of Environmental and Chemical Engineering, Shanghai University of Electric Power, Shanghai 200090, PR China.
Chen-Yan
CY
Hu
State Key Laboratory of Pollution Control and Resources Reuse, Key Laboratory of Yangtze Aquatic Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China.
Tian-Yang
TY
Zhang
State Key Laboratory of Pollution Control and Resources Reuse, Key Laboratory of Yangtze Aquatic Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China.
Nai-Yun
NY
Gao
D002700:Chloramines / Q000737:chemistry; D002713:Chlorine / Q000737:chemistry; D017606:Chlorine Compounds / Q000737:chemistry; D003287:Contrast Media / Q000737:chemistry; D004203:Disinfection / Q000379:methods*; D004307:Dose-Response Relationship, Radiation; D006900:Hydroxylation; D007454:Iodides / Q000737:chemistry*; D007479:Iopamidol / Q000737:chemistry*; D007700:Kinetics; D010084:Oxidation-Reduction; D010087:Oxides / Q000737:chemistry; D010782:Photolysis; D021241:Spectrometry, Mass, Electrospray Ionization; D014466:Ultraviolet Rays; D014874:Water Pollutants, Chemical / Q000737:chemistry*
D002700:Chloramines; D017606:Chlorine Compounds; D003287:Contrast Media; D007454:Iodides; D010087:Oxides; D014874:Water Pollutants, Chemical; D002713:Chlorine; C025109:chlorine dioxide; D007479:Iopamidol; C030816:chloramine
Chlorine; Chlorine dioxide; Iodinated disinfection by-products (I-DBPs); Kinetics; Monochloramine; UV irradiation