School of Environmental Science and Engineering, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Sun Yat-sen University, Guangzhou, 510006, China.
School of Environmental Science and Engineering, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Sun Yat-sen University, Guangzhou, 510006, China.
Water Res. 2019 Nov 15;165:115023. doi: 10.1016/j.watres.2019.115023. Epub 2019 Aug 22.
Purine and pyrimidines are present an important pool of dissolved organic nitrogen in aqueous medias and also precursors of disinfection byproducts. The degradation kinetics of cytosine and adenine-model pyrimidine and purine compounds-were investigated along with their transformation pathways leading to the formation of disinfection byproducts during two typical multi-barrier disinfection processes: UV irradiation and UV/chlorine pretreatment followed by post-chlorination. UV irradiation followed by post-chlorination enhanced the degradation of cytosine and adenine (by 17.1 and 26.1%, respectively), but it also generated more byproduct precursors compared to chlorination alone. The presence of reactive species in the UV/chlorine treatment greatly enhanced cytosine and adenine degradation (by 61.8 and 123.0%) but generated even more disinfection byproducts. Compared to 24 h chlorination, the concentrations of byproducts increased by up to 361.6% for cytosine and 85.1% for adenine with longer UV/chlorine treatment (from 2 to 30 min). Thirty minutes of combined UV/chlorine treatment decreased the total organic chlorine produced from cytosine by 34.4% (from 233.8 to 153.3 μg Cl L) but it increased byproduct generation by 68.3% compared with 24 h of simple chlorination. The TOCl from adenine increased by 50.0% (from 9.2 to 18.4 μg Cl L) but byproduct generation was 11.0% less after 30 min of UV/chlorine pretreatment followed by 24 h of chlorination. The intermediates generated were analyzed in detail and multiple transformation pathways leading to byproduct formation are proposed.
嘌呤和嘧啶是水介质中溶解有机氮的重要来源，也是消毒副产物的前体。研究了胞嘧啶和腺嘌呤（嘧啶和嘌呤模型化合物）在两种典型的多屏障消毒过程中的降解动力学及其转化途径，导致消毒副产物的形成：紫外线照射和紫外线/氯预处理后再加氯。紫外线照射后再加氯可提高胞嘧啶和腺嘌呤的降解（分别提高 17.1%和 26.1%），但与单独氯化相比，也生成了更多的副产物前体。UV/氯处理中活性物质的存在大大提高了胞嘧啶和腺嘌呤的降解（分别提高了 61.8%和 123.0%），但生成了更多的消毒副产物。与 24 小时氯化相比，更长时间的 UV/氯处理（从 2 分钟到 30 分钟）使胞嘧啶的副产物浓度增加了高达 361.6%，腺嘌呤的副产物浓度增加了 85.1%。30 分钟的联合 UV/氯处理使胞嘧啶产生的总有机氯减少了 34.4%（从 233.8 减少到 153.3μg Cl L），但与 24 小时的简单氯化相比，副产物生成增加了 68.3%。腺嘌呤的 TOCl 增加了 50.0%（从 9.2 增加到 18.4μg Cl L），但经过 30 分钟的 UV/氯预处理和 24 小时的氯化后，副产物生成减少了 11.0%。详细分析了生成的中间体，并提出了导致副产物形成的多种转化途径。
