Photodegradation of iodate by medium-pressure UV irradiation and formation of I-THM in sequential chloramination
ZHANG Fan, XU Bin, WANG Zhen, WANG An-qi
State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China
Abstract：Effects of Natural Organic Matter (NOM), iodide on the degradation of iodate by medium-pressure UV were investigated. Effects of solution pH, chloramine dosage, and bromide concentration on the formation of iodinated trihalomethanes (I-THMs) during post-chloramination were also studied. It was found that iodate can be degraded by medium pressure UV irradiation. The pseudo-first-order reaction rate constant was determined to be (0.403±0.059)×10-3s-1 when the UV intensity was 8.5mW/cm2. The reaction could be promoted by the addition of NOM but impeded by the addition of iodide. I-THMs could be formed if water containing iodate was treated with UV/chloramination process. Therefore, special attention should be paid to iodate as a kind of I-THM precursor in drinking water treatment plants when medium-pressure UV/chloramination disinfection process was applied.
张帆, 徐斌, 王震, 王安琪. 中压紫外对碘酸根的降解及后续氯胺化I-THM生成特性[J]. 中国环境科学, 2017, 37(2): 592-597.
ZHANG Fan, XU Bin, WANG Zhen, WANG An-qi. Photodegradation of iodate by medium-pressure UV irradiation and formation of I-THM in sequential chloramination. CHINA ENVIRONMENTAL SCIENCECE, 2017, 37(2): 592-597.
Gong T, Zhang X. Determination of iodide, iodate and organoiodine in waters with a new total organic iodine measurement approach[J]. Water research, 2013,47(17):6660-9.
Zhang T Y, Lin Y L, Wang A Q, et al. Formation of iodinated trihalomethanes during UV/chloramination with iodate as the iodine source[J]. Water Research, 2016,98:199-205.
[4]
Farkas L, Klein F. On the Photo-Chemistry of Some Ions in Solution[J]. The Journal of Chemical Physics, 1948,16(9):886-93.
[5]
Rahn R O, Bolton J, Stefan M I. The lodide/lodate actinometer in UV disinfection:Determination of the fluence rate distribution in UV reactors[J]. Photochemistry and photobiology, 2006,82(2):611-5.
[6]
Saunders R W, Kumar R, Macdonald S M, et al. Insights into the photochemical transformation of iodine in aqueous systems:Humic acid photosensitized reduction of iodate[J]. Environmental Science & Technology, 2012,46(21):11854-61.
[7]
Kulovaara M, Corin N, Backlund P, et al. Impact of UV 254-radiation on aquatic humic substances[J]. Chemosphere, 1996,33(5):783-90.
[8]
Ye T, Xu B, Lin Y L, et al. Formation of iodinated disinfection by-products during oxidation of iodide-containing water with potassium permanganate[J]. Journal of Hazardous Materials, 2012,241:348-54.
[9]
Rahn R O. Potassium iodide as a chemical actinometer for 254nm radiation:use of lodate as an electron scavenger[J]. Photochemistry and Photobiology, 1997,66(4):450-5.
[10]
Bichsel Y, Von Gunten U. Oxidation of iodide and hypoiodous acid in the disinfection of natural waters[J]. Environmental Science & Technology, 1999,33(22):4040-5.
Phillip N H, G Rten E, Diyamandoğlu V. Transformation of bromine species during decomposition of bromate under UV light from low pressure mercury vapor lamps[J]. Ozone:Science and Engineering, 2006,28(4):217-28.
[13]
Wang Z, Xu B, Lin Y-L, et al. A comparison of iodinated trihalomethane formation from iodide and iopamidol in the presence of organic precursors during monochloramination[J]. Chemical Engineering Journal, 2014,257:292-8.
[14]
Trofe T W, Inman G W, Johnson J D. Kinetics of monochloramine decomposition in the presence of bromide[J]. Environmental Science & Technology, 1980,14(5):544-9.
[15]
Bousher A, Brimblecombe P, Midgley D. Kinetics of reactions in solutions containing monochloramine and bromide[J]. Water Research, 1989,23(8):1049-58.
[16]
Hua G, Reckhow D A, Kim J. Effect of bromide and iodide ions on the formation and speciation of disinfection byproducts during chlorination[J]. Environmental Science & Technology, 2006, 40(9):3050-6.
