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三唑酮(Triadimefon,TDF),又名粉锈宁、百里通,是一种广泛用于植物病虫害防治的三唑类杀菌剂[1],具有高效、低毒、残留期长、内附性强等特点[2–4]。2015年我国TDF商品使用量为1.43万吨[5],受农业面源污染影响,TDF在不同水环境中被频繁检出。付岩[6]发现浙江诸暨稻田周围地表水中TDF的浓度高达到12 μg·L−1,附近鱼塘和河流也会受到影响,检出浓度为0.1—0.4 μg·L−1。刘娜等[7]调查了太湖流域饮用水源地、入湖河口及湖体中丰水期的TDF暴露水平,发现TDF的检出率为100%,检出浓度为0.002—0.007 μg·L−1。游明华[8]对九龙江的16个点位进行检测,发现丰水期TDF的检出率为43.8%。刘园等[9]调查了贵阳市4个主要集中式饮用水源地冬季枯水期的有机氯农药残留情况,发现TDF的检出率为36.4%,检出浓度为0.185—5.22 μg·L−1。Stamatis等[10]根据欧盟风险评估技术指南推荐的方法,计算出三唑酮的预测无观察效应浓度(predicted no effect concentration,PNEC)为0.34 μg·L−1。根据计算出的PNEC值,说明部分水环境中检出的三唑酮的浓度会对水生生物存在较高风险,可能会影响生态健康安全。
TDF不仅对水生生物具有急性致死、致畸以及慢性毒性效应[5,11–14],还能引起大鼠的运动活动增加和单胺代谢改变而发生病变[15],其在小鼠和大鼠的肝脏中具有致瘤性[16–17]。2006年欧盟(EU)将TDF列入具有内分泌-生殖干扰毒性的农药及其代谢产物名单。TDF不仅会破坏水生态环境,还对人类饮水安全和健康存在潜在的威胁[18]。常规水处理工艺是以降低原水浊度、除细菌等为主要目的,对TDF等农药的去除效果并不理想[19]。紫外/氯(UV/Cl)工艺被认为是一种有效的新兴高级氧化工艺,可用于微污染物降解[20–24],该体系具有高效、转化完全、降解反应时间短等优点。在UV/Cl体系中,氯发生光解反应,产生具有高氧化电位的羟基自由基(HO·)和包括Cl·和Cl2·–等的活性氯(reactive chlorine species,RCS)[25]。HO·和Cl·可以通过电子转移,脱氢和加成反应与有机污染反应[26–27]。在该体系中可以生成一级羟基自由基HO·和Cl·以及ClO·和Cl2·–,其过程如下式(1—5)所示[26,28–29]。HO·和RCS(即Cl·、ClO·和Cl2·–)共同作用,通过其高氧化性降解微污染物。
本研究在UV/Cl体系中降解TDF,考察了不同反应条件下TDF的降解效果,分别探究不同TDF浓度,不同次氯酸钠(NaClO)浓度,不同pH,溴离子(Br-)浓度和叔丁醇(t-BuOH)对降解效果的影响。利用超高效液相色谱质谱联用仪(UPLC-MS/MS)全扫描模式检测了降解反应中间产物,并推断了可能的降解路径,为去除水环境中的三唑类杀菌剂提供了技术和理论支持。
UV/Cl降解水中三唑酮的影响因素和机理
Influencing factors and mechanism of UV/Cl degradation of triazolone in water
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摘要: 采用UV/Cl高级氧化技术去除水中三唑酮(TDF),并研究了TDF在UV/Cl体系中的降解动力学、影响因素和降解机理。对比单独UV、单独次氯酸钠(NaClO)和UV/Cl的3种条件下TDF的降解效果,发现UV/Cl体系能有效降解TDF。考察了TDF的初始浓度、NaClO初始浓度、不同初始pH、溴离子(Br-)和叔丁醇(t-BuOH)对降解效果的影响。结果表明,UV/Cl降解TDF符合一级动力学方程。pH对降解反应有较大影响,在pH为3时,反应速率最慢,表观反应动力学常数(kobs)为0.0150 min−1;pH为11时,反应速率最快,kobs为0.211 min−1。Br−初始浓度为1 μmol·L−1时对降解反应有一定的抑制作用,当Br−初始浓度高于5 μmol·L−1时,Br−初始浓度越高对降解反应的促进作用越强。在UV/Cl体系中加入猝灭剂t-BuOH后,kobs降低了33.5%,表明UV/Cl体系中有HO·和Cl·参与反应。通过超高效液相色谱质谱联用仪(UPLC-MS/MS)全扫描模式鉴定了TDF降解的中间体,推断出7种可能的降解中间产物,UV/Cl降解TDF的反应机理包括亲电取代和消除等。Abstract: The UV/Cl was used to remove triazolone (TDF) in water, and the degradation kinetics and degradation mechanism of TDF in the UV/Cl system were studied. By comparing the degradation effects of UV alone, sodium hypochlorite (NaClO) alone, and UV/Cl system, it was found that the UV/Cl system can degrade TDF effectively. The influence factors of NaClO, TDF initial concentration, pH values, bromide ion (Br−) initial concentration and isopropanol (t-BuOH) were investigated in the degradation process. The results showed that the degradation of TDF by UV/Cl conformed to the first-order kinetic equation. pH has a great influence on the degradation reaction, the degradation rate was the slowest and fastest when the pH at 3 and 11, and the apparent reaction kinetic constant (kobs) was 0.0150 min−1 and 0.211 min−1, respectively; the inhibitory effect of the degradation reaction was found when the initial concentration of Br− was 1 μmol·L−1. When the initial concentration of Br− was higher than 5 μmol·L−1, the higher the initial concentration of Br−, the stronger the promotion effect on the degradation reaction. After added the quencher isopropanol (t-BuOH) to the UV/Cl system, the kobs was decreased by 33.5%. This indicated that HO· and Cl· were involved in the UV/Cl system. The intermediates of TDF degradation were identified by UPLC-MS/MS in full-scan mode, and seven possible degradation intermediates were proposed. The reaction mechanisms of UV/Cl system including electrophilic substitution and elimination.
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Key words:
- UV/Cl /
- triadimefon /
- reaction kinetics /
- degradation mechanism
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表 1 三唑酮的理化性质
Table 1. Physicochemical properties of triadimefon
目标物
Compound结构
Structure分子式
Molecular formula分子量
Molecular weightCAS 水溶解性/(g·100 mL−1)
Water solubility三唑酮 C14H16ClN3O2 293.7 43121-43-3 0.026 表 2 三唑酮液相洗脱梯度条件
Table 2. Triazolone liquid elution gradient conditions
时间/min
Time流速/(mL·min−1)
Flow rate流动相A/%
Mobile phase A流动相B/%
Mobile phase B0.00 0.400 80.0 20.0 0.50 0.400 80.0 20.0 3.50 0.400 5.0 95.0 4.70 0.400 5.0 95.0 4.80 0.400 80.0 20.0 5.50 0.400 80.0 20.0 表 3 TDF的UPLC-MS/MS参数
Table 3. UPLC-MS/MS parameters for the TDF
目标化合物Compound 母离子
Parent ion
(m/z)保留时间/min
Retention time子离子
Product ion
(m/z)锥孔电压/V
Cone voltage碰撞电压/V
Collision voltageTDF 294.06 2.61 197.08 16 14 225.02 16 12 -
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