紫外-氯降解非那西丁影响因素及机理研究
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摘要
采用紫外/氯(UV/Cl_2)高级氧化工艺,研究了其对水体中的新兴污染物非那西丁(PNT)的降解效果。结果表明,PNT的降解遵循准1级动力学,在pH为7.2,UV辐照度59μW/cm~2,Cl_2和H_2O_2的浓度分别是0.3 mmol/L时,UV/Cl_2降解PNT的第1阶速率常数k_(obs)分别是Cl_2和UV/H_2O_2的4.3和8.4倍。随着Cl_2的浓度从0.1 mmol/L增加到0.5 mmol/L,相应的k_(obs)从0.022 9 min~(-1)增加到了0.216 min~(-1)。k_(obs)受pH的影响不显著,当HCO_3-浓度从0增加到10 mmol/L时,k_(obs)减少56.5%,当NOM的质量浓度从0增加到10 mg/L时,k_(obs)减少75.4%。pH为7.2时,氯化、羟自由基(HO·)和活性氯(RCS)对UV/Cl_2降解PNT的贡献分别为26.33%、14.6%和59.07%。UV/Cl_2对PNT具有明显的降解效果,且会受到Cl_2含量、碱度和NOM的影响,HO·及RCS的存在是UV/Cl_2强化降解PNT的主要原因。
The degradation of the emerging pollutant phenacetin(PNT) in water by UV/Cl_2 was systemically investigated using UV/Cl_2 advanced oxidation process(AOP). The results showed that the degradation of PNT followed the quasi-first-order kinetics. When the pH was 7.2, UV irradiance was 59 μW/cm~2 and concentration of Cl_2/H_2O_2 was 0.3 mmol/L, the first order rate constants (kobs) of UV/Cl_2 was 4.3 and 8.4 times than that of Cl_2 and UV/H_2O_2,respectively. As the chlorine concentration increased from 0.1 to 0.5 mmol/L, the corresponding k_(obs) increased from 0.022 9 to 0.216 min~(-1). k_(obs)was not significantly affected by pH. When the concentration of HCO_3- increased from 0 to 10 mmol/L, the k_(obs) decreased by 56.5%, and when the mass concentration of NOM increased from 0 to 10 mg/L, k_(obs) decreased by 75.4%. The contribution of chlorination, hydroxyl radical(HO·) and active chlorine(RCS) to UV/Cl_2 degradation of PNT at pH 7.2 was 26.33%, 14.6% and 59.07%, respectively. The UV/Cl_2 process had obvious degradation effect on PNT, which was affected by chlorine content, alkalinity and NOM. The presence of HO·and RCS was the main reason for the enhanced degradation of PNT by UV/Cl_2.
The degradation of the emerging pollutant phenacetin(PNT) in water by UV/Cl_2 was systemically investigated using UV/Cl_2 advanced oxidation process(AOP). The results showed that the degradation of PNT followed the quasi-first-order kinetics. When the pH was 7.2, UV irradiance was 59 μW/cm~2 and concentration of Cl_2/H_2O_2 was 0.3 mmol/L, the first order rate constants (kobs) of UV/Cl_2 was 4.3 and 8.4 times than that of Cl_2 and UV/H_2O_2,respectively. As the chlorine concentration increased from 0.1 to 0.5 mmol/L, the corresponding k_(obs) increased from 0.022 9 to 0.216 min~(-1). k_(obs)was not significantly affected by pH. When the concentration of HCO_3- increased from 0 to 10 mmol/L, the k_(obs) decreased by 56.5%, and when the mass concentration of NOM increased from 0 to 10 mg/L, k_(obs) decreased by 75.4%. The contribution of chlorination, hydroxyl radical(HO·) and active chlorine(RCS) to UV/Cl_2 degradation of PNT at pH 7.2 was 26.33%, 14.6% and 59.07%, respectively. The UV/Cl_2 process had obvious degradation effect on PNT, which was affected by chlorine content, alkalinity and NOM. The presence of HO·and RCS was the main reason for the enhanced degradation of PNT by UV/Cl_2.
引文
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[4]BENITEZ F J,REAL F J,ACERO J L.et al.Removal of selected pharmaceuticals in waters by photochemical processes[J].J Chem Technol Biotechnol,2009,84(8):1186-1195.
[5]ACERO J L,JAVIER BENITEZ F,REAL F J.et al.Kinetics of aqueous chlorination of some pharmaceuticals and their elimination from water matrices[J].Water Res,2010,44(14):4158-4170.
[6]WOLS B A,HOFMAN-CARIS C H M.Review of photochemical reaction constants of organic micropollutants required for UV advanced oxidation processes in water[J].Water Res,2012,46(9):2815-2827.
[7]YANG Y,PIGNATELLO J J,MA J.et al.Effect of matrix components on UV/H2O2and UV/S2O82-advanced oxidation processes for trace organic degradation in reverse osmosis brines from municipal wastewater reuse facilities[J].Water Res,2016,89:192-200.
[8]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].J Hazard Mater,2016,307:119-126.
[9]NAM S W,YOON Y,CHOI D J,et al.Degradation characteristics of metoprolol during UV/chlorination reaction and a factorial design optimization[J].J Hazard Mater,2015,285:453-463.
[10]SICHEL C,GARCIA C,ANDRE K.Feasibility studies:UV/chlorine advanced oxidation treatment for the removal of emerging contaminants[J].Water Res,2011,45(19):6371-6380.
[11]WANG D,BOLTON J R,HOFMANN R.Medium pressure UVcombined with chlorine advanced oxidation for trichloroethylene destruction in a model water[J].Water Res,2012,46(15):4677-4686.
[12]APHA A,WEF.Standard methods for the examination of water and wastewater,20th ed[J].American Public Health Assoc,1998,
[13]CRITTENDEN J C,HU S M,HAND D W,et al.A kinetic model for H2O2/UV process in a completely mixed batch reactor[J].Water Res,1999,33(10):2315-2328.
[14]FENG Y,SMITH D W,BOLTON J R.Photolysis of aqueous free chlorine species(NOCI and OCl-)with 254 nm ultraviolet light[J].Journal of Environmental Engineering and Science,2007,6(3):277-284.
[15]HERRMANN H.On the photolysis of simple anions and neutral molecules as sources of O-/OH,SOx-and Cl in aqueous solution[J].Physical Chemistry Chemical Physics,2007,9(30):3935-3964.
[16]WATTS M J,LINDEN K G.Chlorine photolysis and subsequent OH radical production during UV treatment of chlorinated water[J].Water Res,2007,41(13):2871-2878.
[17]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.
[18]BEITZ T,BECHMANN W,MITZNER R.Investigations of reactions of selected azaarenes with radicals in water.2.Chlorine and bromine radicals[J].Journal of Physical Chemistry A,1998,102(34):6766-6771.
[19]MARTIRE D O,ROSSO J A,BERTOLOTTI S,et al.Kinetic study of the reactions of chlorine atoms and Cl(2)(center dot-)radical anions in aqueous solutions.II.Toluene,benzoic acid,and chlorobenzene[J].Journal of Physical Chemistry A,2001,105(22):5385-5392.
[20]LEE C,YOON J,VON GUNTEN U.Oxidative degradation of N-nitrosodimethylamine by conventional ozonation and the advanced oxidation process ozone/hydrogen peroxide[J].Water Res,2007,41(3):581-590.
[21]HASEGAWA K,NETA P.Rate constants and mechanisms of reaction of Cl2-radicals[J].J.Phys.Chem,1978,82(8):854-857.
[22]BUXTON G V,GREENSTOCK C L,HELMAN W P,et al.Criticalreview of rate constants for reactions of hydrated electrons,hydrogenatoms and hydroxyl radicals(·OH/O·-)in aqueous-solution[J].Journal of Physical and Chemical Reference Data,1988,17(2):513-886.