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题名: 高锰酸钾、活性氯氧化微污染物的动力学研究
作者: 宋德安
学位类别: 博士
答辩日期: 2014
授予单位: 中国科学院研究生院
授予地点: 北京
导师: 刘会娟
关键词: 高锰酸根 ; permanganate ; 活性氯 ; free chlorine ; 微污染物 ; micropollutants ; 动力学 ; kinetics ; 机理 ; mechanism
其他题名: The kinetic investigations in the degradation of micropollutants by permanganate or free chlorine
中文摘要:       微污染物在地表水与地下水中的大量存在可能会对生态环境与人类健康造成长期的影响。使用高锰酸根或活性氯对微污染物进行氧化是目前常用的处理方法。然而,对于高锰酸根在不同pH 条件下氧化微污染物的动力学与机制还不是很清楚。而对于活性氯来说,测定微污染物快速氯化反应动力学过程还有很大的困难。 本文首先使用了停流光谱、液相色谱质谱以及理论计算等方法,研究了高锰酸钾在酸、碱、中性条件下对微污染物的氧化动力学与机制。在酸性条件下高锰酸根氧化磺胺甲恶唑的反应中,其速率控制步骤是高锰酸根对氮氢键的攻击。其中高锰酸根对氮氢键的氧化是一步反应,而质子化的高锰酸根对氮氢键的氧化是分步的电子质子转移反应。质谱分析中,磺胺甲恶唑的质子化位点在异恶唑环的氮原子上。碎片离子生成的主要途径是硫氮键与碳硫键的异裂以及氨基苯磺酸阳离子的分步重排。在中性与碱性的条件下,高锰酸钾与四环素的反应速率常数都是随着形态的变化而变化。中性条件下的反应路径是对双键与苯环结构的氧化。而碱性条件下是通过氢氧根离子与四环素复合从而生成了高活性的中间体,并使氧化反应优先发生在四环素的苯环结构上。在此过程中,四环素的分子最高占据轨道完成了从双键到苯环的转移。在中性条件下高锰酸钾氧化乙二胺四乙酸的反应中,反应速率常数也是随着pH 变化而变化的。 最后利用停流光谱、竞争动力学、显色剂三者结合的方式建立了测定快速氯化动力学的方法。首先建立了氯与二乙基对苯二胺(DPD)在pH=6.75-?8.90 以及温度18-?37oC 范围内的二级反应动力学模型。然后使用DPD 作为参照物探针,测定了四环素、氨以及四种氨基酸的二级氯化反应动力学常数。最后通过与文献报道的数据比较以及塔夫特方程理论分析的方式验证了方法的可行性。
英文摘要:
      The ubiquitous presence of micropollutants in surface and groudwater may cause long term effects on aquatic ecology and on human health. Chemical oxidation using permanganate or free chlorine is the commonly used method for treating micropollutants. However, the kinetics and mechanism remain unclear for the permanganate oxidation of micropollutants under different pH conditions. For rapid chlorination reactions, it is still a big challenge to determine their rate constants. In combination of stopped-flow spectrometer, LC-MS, and theoretical analysis, we investigated the kinetics and mechanism of the permanganate oxidation of micropollutants in acidic, neutral, and alkaline aqueous solutions. The rate-limiting step of acidic permanganate oxidation of sulfamethoxazole is the attack of permanganate at N-H bond. The results established that the N-H bond oxidation by MnO4– is a concerted mechanism, whereas the HMnO4 oxidation of N-H bond goes through a stepwise electron-proton transfer. In MS analysis, the protonation site of sulfamethoxazole was located at the nitrogen atom of the isoxazole ring. Formation of the fragment ions were recognized as the results of heterolytic S-N bond and C-S bond cleavage and was attributed to a stepwise rearrangement reaction. In neutral and alkaline aqueous solutions, the rate constants of the reactions between tetracycline and permanganate depended on the species distribution. The reaction in neutral pH condition was the permanganate oxidation of double bond and aromatic ring. The reaction in alkaline medium was the permanganate oxidation of a higher charge complex formed by tetracycline and hydroxide ion. This resulted in the transfer of HOMO from double bond to aromatic ring, leading to the selective oxidation of the phenolate-like moiety. In a more broad pH range, the pH-dependent kinetics was also found to be applicable in the permanganate oxidation of EDTA. Finally, we combined stopped-flow spectrometer, competition kinetics, and colorimetric reagent to propose a novel method to determine the rapid chlorination reactions. A kinetic equation was first derived to estimate the reaction rate constant of N,N-diethyl-p-phenylenediamine (DPD) towards chlorine under a given pH (6.75–8.90) and temperature condition (18–37 oC). By using DPD as a reference probe, we determined the chlorination rate constants of several representative compounds including tetracycline, ammonia, and four α-amino acids. The developed method was validated through comparing the experimentally measured chlorination rate constants of the selected compounds with those obtained or calculated from literature and analyzing with Taft’s correlation as well.
内容类型: 学位论文
URI标识: http://ir.rcees.ac.cn/handle/311016/35197
Appears in Collections:环境水质学国家重点实验室_学位论文

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Recommended Citation:
宋德安. 高锰酸钾、活性氯氧化微污染物的动力学研究[D]. 北京. 中国科学院研究生院. 2014.
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