中压紫外对碘酸根的降解及后续氯胺化I-THM生成特性
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摘要
以碘酸根为研究对象,研究中压紫外对碘酸根的降解速率,天然有机物及共存碘离子对其降解速率影响,在此基础上,采用氯胺消毒方式,考察溶液pH、氯胺投加量及溴离子浓度对碘代消毒副产物的生成影响.研究发现,饮用水中压紫外消毒工艺对碘酸根具有明显降解作用,其光反应产物为碘离子.降解过程符合拟一级反应动力学方程,中压紫外光强为8.5mW/cm~2时,其拟一级反应速率常数为(0.403±0.059)×10~(-3)s~(-1).水中天然有机物(NOM)可促进紫外光对碘酸根的降解,而初始碘离子浓度会抑制碘酸根降解.含碘酸盐原水经中压紫外光照射后,后续氯胺消毒工艺将大量产生碘代三卤甲烷(I-THMs).因此在采用中压紫外/氯胺联合消毒的净水工艺中,碘酸根转化后形成碘代消毒副产物的风险应当引起关注.
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~(-3)s~(-1) when the UV intensity was 8.5mW/cm~2.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.
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~(-3)s~(-1) when the UV intensity was 8.5mW/cm~2.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.
引文
[1]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.
[2]刘列钧,王海燕,李秀维,等.我国水源型高碘地区水碘形态的研究[J].疾病监测,2012,(11):891-3.
[3]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 UV254-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.
[11]黄河,徐斌,朱文倩,等.长江沿线城市水源氯(胺)化消毒副产物生成潜能研究[J].中国环境科学,2014,34(10):2497-504.
[12]Phillip N H,G Rten E,Diyamando?lu 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.
[2]刘列钧,王海燕,李秀维,等.我国水源型高碘地区水碘形态的研究[J].疾病监测,2012,(11):891-3.
[3]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 UV254-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.
[11]黄河,徐斌,朱文倩,等.长江沿线城市水源氯(胺)化消毒副产物生成潜能研究[J].中国环境科学,2014,34(10):2497-504.
[12]Phillip N H,G Rten E,Diyamando?lu 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.