紫外-氯降解非那西丁影响因素及机理研究

Influencing Factors and Mechanism of Ultraviolet/Chlorine Degradation on Phenacetin

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/Cl2 was systemically investigated using UV/Cl2 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/cm2 and concentration of Cl2/H2O2 was 0.3 mmol/L, the first order rate constants (kobs) of UV/Cl2 was 4.3 and 8.4 times than that of Cl2 and UV/H2O2,respectively. As the chlorine concentration increased from 0.1 to 0.5 mmol/L, the corresponding kobs increased from 0.022 9 to 0.216 min-1. kobswas not significantly affected by pH. When the concentration of HCO3- increased from 0 to 10 mmol/L, the kobs decreased by 56.5%, and when the mass concentration of NOM increased from 0 to 10 mg/L, kobs decreased by 75.4%. The contribution of chlorination, hydroxyl radical(HO·) and active chlorine(RCS) to UV/Cl2 degradation of PNT at pH 7.2 was 26.33%, 14.6% and 59.07%, respectively. The UV/Cl2 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/Cl2.