Photodegradation of etridiazole by UV radiation during drinking water treatment.
Photodegradation of etridiazole by UV radiation during drinking water treatment.
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DOI：
10.1016/j.chemosphere.2009.04.052
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发表时间：
2009-07
期刊：
影响因子：
8.8
通讯作者：
Chao Liu;Z. Qiang;Fang Tian;Tao Zhang
中科院分区：
文献类型：
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作者：
Chao Liu;Z. Qiang;Fang Tian;Tao Zhang
研究了在254 nm紫外光照射下，乙咪唑（ETZ）在水中的光降解。结果表明，模拟的一级速率常数随ETZ初始浓度的增加而减小（即，5、20和30μM），在6.0 - 8.0范围内未显示任何pH依赖性。在pH 7.0时，量子产率为0.46±0.02molE− 1。在ETZ光降解过程中，产生了0 ~ 1.0μM的痕量H2 O2。直接光降解是负责的ETZ在蒸馏水中的紫外线辐射的分解。3种有机副产物分别为5-乙氧基-3-二氯甲基-1，2，4-噻二唑、5-乙氧基-1，2，4-噻二唑-3-羧酸和5-乙氧基-3-羟基-1，2，4-噻二唑。初始ETZ中约90%的氯质量在光降解结束时以Cl−形式释放。相反，硫酸盐和硝酸盐的形成是微不足道的。一般来说，ETZ在地下水中的衰减速度比在砂过滤水或地表水中快。可以合理推断，在大多数采用紫外线辐射消毒的水处理厂，ETZ在典型的40 mJcm − 2紫外线剂量下可能无法有效去除。
The photodegradation of etridiazole (ETZ) in water by UV radiation at 254nm was investigated. Results indicate that the simulated first-order rate constants decreased with the increase of initial ETZ concentration (i.e., 5, 20 and 30μM), and did not show any pH dependence within the range from 6.0 to 8.0. The quantum yield was 0.46±0.02molE−1at pH 7.0. H2O2was generated at trace levels in the range from 0 to 1.0μM during photodegradation of ETZ. Direct photodegradation was responsible for the decomposition of ETZ in distilled water by UV radiation. Three organic byproducts were identified: 5-ethoxy-3-dichloromethyl-1,2,4-thiadiazole, 5-ethoxy-1,2,4-thiadiazole-3-carboxylic acid and 5-ethoxy-3-hydroxyl-1,2,4-thiadiazole. About 90% of chloro mass in the initial ETZ was released as Cl−at the end of photodegradation. In contrast, the formation of sulfate and nitrate was insignificant. In general, ETZ decayed more quickly in groundwater than in sand-filtered or surface water. It is reasonably deduced that ETZ may not get removed effectively under a typical UV dose of 40mJcm−2at most water treatment plants that employ UV radiation for disinfection.