Abstract: In this paper,the reaction mechanism of UV/chlorine process is fully discussed and the effects of UV wavelength,concentration of free chlorine,pH value and background substances in water on the process are introduced.The degradation mechanism of pollutants in water is described.Finally,the current status,challenges and future directions are also summarized.
[1] Xiang Y,Fang J,Shang C.Kinetics and pathways of ibuprofen degradation by the UV/chlorine advanced oxidation process[J].Water Research,2016,90:301-308. [2] Jin J,El-Din M G,Bolton J R.Assessment of the UV/chlorine process as an advanced oxidation process[J].Water Research,2011,45(4):1890-1896. [3] Sichel C,Garcia C,Andre K.Feasibility studies:UV/chlorine advanced oxidation treatment for the removal of emerging contaminants[J].Water Research,2011,45(19):6371-6380. [4] Kwon M,Yoon Y,Kim S,et al.Removal of sulfamethoxazole,ibuprofen and nitrobenzene by UV and UV/chlorine processes:A comparative evaluation of 275 nm LED-UV and 254 nm LP-UV[J].Science of the Total Environment,2018,637:1351-1357. [5] Li M,Xu B,Liungai Z,et al.The removal of estrogenic activity with UV/chlorine technology and identification of novel estrogenic disinfection by-products[J].Journal of Hazardous Materials,2016,307:119-126. [6] Wang W L,Wu Q Y,Huang N,et al.Synergistic effect between UV and chlorine (UV/chlorine) on the degradation of carbamazepine:Influence factors and radical species[J].Water Research,2016,98:190-198. [7] Huang N,Wang T,Wang W L,et al.UV/chlorine as an advanced oxidation process for the degradation of benzalkonium chloride:Synergistic effect,transformation products and toxicity evaluation[J].Water Research,2017,114:246-253. [8] Fang J,Fu Y,Shang C.The roles of reactive species in micropollutant degradation in the UV/free chlorine system[J].Environmental Science & Technology,2014,48(3):1859-1868. [9] Wang W L,Wu Q Y,Li Z M,et al.Light-emitting diodes as an emerging UV source for UV/chlorine oxidation:Carbamazepine degradation and toxicity changes[J].Chemical Engineering Journal,2017,310:148-156. [10] Zhu Y,Wu M,Gao N,et al.Degradation of phenacetin by the UV/chlorine advanced oxidation process:Kinetics,pathways,and toxicity evaluation[J].Chemical Engineering Journal,2018,335:520-529. [11] Kim T K,Moon B R,Kim T,et al.Degradation mechanisms of geosmin and 2-MIB during UV photolysis and UV/chlorine reactions[J].Chemosphere,2016,162:157-164. [12] Wu Z,Guo K,Fang J,et al.Factors affecting the roles of reactive species in the degradation of micropollutants by the UV/chlorine process[J].Water Research,2017,126:351-360. [13] Kong X,Jiang J,Ma J,et al.Degradation of atrazine by UV/chlorine:Efficiency,influencing factors,and products[J].Water Research,2016,90:15-23. [14] Wu Z,Fang J,Xiang Y,et al.Roles of reactive chlorine species in trimethoprim degradation in the UV/chlorine process:Kinetics and transformation pathways[J].Water Research,2016,104:272-282. [15] Wang D,Bolton J R,Hofmann R.Medium pressure UV combined with chlorine advanced oxidation for trichloroethylene destruction in a model water[J].Water Research,2012,46(15):4677-4686. [16] Watts M J,Linden K G.Chlorine photolysis and subsequent OH radical production during UV treatment of chlorinated water[J].Water Research,2007,41(13):2871-2878. [17] Modirshahla N M,Behnajady M A.Photooxidative degradation of malachite green (MG) by UV/H2O2:Influence of operational parameters[J].Dyes & Pigments,2006,70(1):54-59. [18] Wang A Q,Lin Y L,Xu B,et al.Kinetics and modeling of iodoform degradation during UV/chlorine advanced oxidation process[J].Chemical Engineering Journal,2017,323:312-319. [19] Guo Z B,Lin Y L,Xu B,et al.Degradation of chlortoluron during UV irradiation and UV/chlorine processes and formation of disinfection by-products in sequential chlorination[J].Chemical Engineering Journal,2016,283:412-419. [20] Kong X,Jiang J,Ma J,et al.Comparative investigation of X-ray contrast medium degradation by UV/chlorine and UV/H2O2[J].Chemosphere,2018,193:655-663. [21] Wang W L,Zhang X,Wu Q Y,et al.Degradation of natural organic matter by UV/chlorine oxidation:Molecular decomposition,formation of oxidation byproducts and cytotoxicity[J].Water Research,2017,124:251-258. [22] Zhang R,Sun P,Boyer T H,et al.Degradation of pharmaceuticals and metabolite in synthetic human urine by UV,UV/H2O2,and UV/PDS[J].Environmental Science & Technology,2015,49(5):3056-3066. [23] Kong X,Wu Z,Ren Z,et al.Degradation of lipid regulators by the UV/chlorine process:Radical mechanisms,chlorine oxide radical (ClO·)-mediated transformation pathways and toxicity changes[J].Water Research,2018,137:242-250. [24] Wang Z,Lin Y L,Xu B,et al.Degradation of iohexol by UV/chlorine process and formation of iodinated trihalomethanes during post-chlorination[J].Chemical Engineering Journal,2016,283:1090-1096. [25] Sun P,Lee W N,Zhang R,et al.Degradation of DEET and Caffeine under UV/Chlorine and Simulated Sunlight/Chlorine Conditions[J].Environmental Science & Technology,2016,50(24):13265-13273. [26] Khan J A,He X,Shah,et al.Kinetic and mechanism investigation on the photochemical degradation of atrazine with activated H2O2,S2O82- and HSO5-[J].Chemical Engineering Journal,2014,252(18):393-403. [27] Dodd M C,Huang C H.Transformation of the antibacterial agent sulfamethoxazole in reactions with chlorine:Kinetics,mechanisms,and pathways[J].Environmental Science & Technology,2004,38(21):5607-5615. [28] Acero J L,Benitez F J,Real F J,et al.Kinetics of aqueous chlorination of some pharmaceuticals and their elimination from water matrices[J].Water Research,2010,44(14):4158-4170. [29] Dong H,Qiang Z,Lian J,et al.Degradation of nitro-based pharmaceuticals by UV photolysis:Kinetics and simultaneous reduction on halonitromethanes formation potential[J].Water Research,2017,119:83-90. [30] Cimetiere N,Laat J D.Effects of UV-dechloramination of swimming pool water on the formation of disinfection by-products:A lab-scale study[J].Microchemical Journal,2014,112(112):34-41.
