Department of Safety Health and Environmental Engineering, Ming Chi University of Technology, Taipei County, Taiwan.
Chemosphere. 2011 Jan;82(2):229-36. doi: 10.1016/j.chemosphere.2010.10.016. Epub 2010 Oct 28.
The purpose of this study is to investigate parathion degradation by Fenton process in neutral environment. The initial parathion concentration for all the degradation experiments was 20 ppm. For hydrogen ion effect on Fenton degradation, the pH varied from 2 to 8 at the [H₂O₂] to [Fe²(+)] ratio of 2-2 mM, and the result showed pH 3 as the most effective environment for parathion degradation by Fenton process. Apparent degradation was also observed at pH 7. The subsequent analysis for parathion degradation was conducted at pH 7 because most environmental parathion exists in the neutral environment. Comparing the parathion degradation results at various Fenton dosages revealed that at Fe²(+) concentrations of 0.5, 1.0 and 1.5 mM, the Fenton reagent ratio ([H₂O₂]/[Fe²(+)]) for best-removing performance were found as 4, 3, and 2, resulting in the removal efficiencies of 19%, 48% and 36%, respectively. Further increase in Fe²(+) concentration did not cause any increase of the optimum Fenton reagent ratio for the best parathion removal. The result from LC-MS also indicated that hydroxyl radicals might attack the PS double bond, the single bonds connecting nitro-group, nitrophenol, or the single bond within ethyl groups of parathion molecules forming paraoxons, nitrophenols, nitrate/nitrite, thiophosphates, and other smaller molecules. Lastly, the parathion degradation by Fenton process at the presence of humic acids was investigated, and the results showed that the presence of 10 mg L⁻¹ of humic acids in the aqueous solution enhanced the parathion removal by Fenton process twice as much as that without the presence of humic acids.
本研究旨在探讨芬顿工艺在中性环境中对硫磷的降解作用。所有降解实验的初始硫磷浓度均为 20ppm。对于氢离子对芬顿降解的影响，在[H₂O₂]与[Fe²(+)]的比值为 2-2mM 时，pH 值从 2 变化到 8，结果表明 pH 值为 3 时是芬顿工艺降解硫磷的最有效环境。在 pH 值为 7 时也观察到明显的降解。由于大多数环境中的硫磷都存在于中性环境中，因此后续的硫磷降解分析在 pH 值为 7 时进行。比较不同芬顿剂量下的硫磷降解结果表明，在 Fe²(+)浓度为 0.5、1.0 和 1.5mM 时，去除效果最佳的芬顿试剂比例([H₂O₂]/[Fe²(+)])分别为 4、3 和 2，去除效率分别为 19%、48%和 36%。进一步增加 Fe²(+)浓度不会导致最佳芬顿试剂比例的任何增加，从而获得最佳的硫磷去除效果。LC-MS 的结果还表明，羟基自由基可能攻击 PS 双键、连接硝基基团的单键、硝基苯酚或硫磷分子中乙基的单键，形成对氧磷、硝基苯酚、硝酸盐/亚硝酸盐、硫代磷酸盐和其他较小的分子。最后，研究了腐殖酸存在下芬顿工艺对硫磷的降解作用，结果表明，在水溶液中存在 10mg/L 的腐殖酸时，芬顿工艺对硫磷的去除率比不存在腐殖酸时提高了两倍。
