紫外线及紫外线/过氧化氢处理对水溶液中对硫磷的降解及副产物生成情况
Degradation and byproduct formation of parathion in aqueous solutions by UV and UV/H(2)O(2) treatment.
作者信息
Wu Changlong, Linden Karl G
机构信息
Department of Civil and Environmental Engineering, Duke University, Durham, NC 27708-0287, USA.
出版信息
Water Res. 2008 Dec;42(19):4780-90. doi: 10.1016/j.watres.2008.08.023. Epub 2008 Sep 3.
The photodegradation of parathion in aqueous solutions by UV and UV/H(2)O(2) processes was evaluated. Direct photolysis of parathion both by LP (low pressure) and MP (medium pressure) lamps at pH 7 was very slow with quantum yields of 6.67+/-0.33x10(-4) and 6.00+/-1.06x10(-4)molE(-1), respectively. Hydrogen peroxide enhanced the photodegradation of parathion through the reaction between UV generated hydroxyl radical and parathion with a second-order reaction rate constant of 9.70+/-0.45x10(9)M(-1)s(-1). An optimum molar ratio between hydrogen peroxide and parathion was determined to be between 300 and 400. Photodegradation of parathion yielded several organic byproducts, of which the paraoxon, 4-nitrophenol, O,O,O-triethyl thiophosphate and O,O-diethyl-methyl thiophosphate were quantified and their occurrence during UV/H(2)O(2) processes were discussed. NO(2)(-), PO(4)(3-), NO(3)(-) and SO(4)(2-) were the major anionic byproducts of parathion photodegradation and their recover ratios were also discussed. A photodegradation scheme suggesting three simultaneous pathways was proposed in the study.
评估了水溶液中对硫磷通过紫外线和紫外线/过氧化氢工艺的光降解情况。在pH值为7时，用低压（LP）灯和中压（MP）灯对硫磷进行直接光解都非常缓慢，量子产率分别为6.67±0.33×10⁻⁴和6.00±1.06×10⁻⁴molE⁻¹。过氧化氢通过紫外线产生的羟基自由基与对硫磷之间的反应增强了对硫磷的光降解，二级反应速率常数为9.70±0.45×10⁹M⁻¹s⁻¹。确定过氧化氢与对硫磷之间的最佳摩尔比在300至400之间。对硫磷的光降解产生了几种有机副产物，其中对氧磷、4-硝基苯酚、O,O,O-三乙基硫代磷酸酯和O,O-二乙基-甲基硫代磷酸酯被定量，并讨论了它们在紫外线/过氧化氢工艺中的出现情况。NO₂⁻、PO₄³⁻、NO₃⁻和SO₄²⁻是对硫磷光降解的主要阴离子副产物，还讨论了它们的回收率。该研究提出了一个表明三种同时发生途径的光降解方案。
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