溶解性有机质对羟基自由基氧化降解有机污染物的影响
发布时间：2018-08-25 13:09
【摘要】：溶解性有机质(DOM)是环境中普遍存在的一类结构组分复杂的混合有机质,其官能团种类丰富,能够通过多种机制与环境中的有机污染物(OPs)发生相互作用,改变污染物环境归趋。由于DOM本身既可以与自由基反应,又可能通过结合作用影响OPs在水中的形态,从而影响OPs与自由基的反应。羟基自由基(·O功是一种氧化能力极强的自由基,不仅在自然界中广泛存在,而且经常被用在高级氧化体系中去除OPs。本研究通过光照H2O2产生-OH,首先考察了不同来源和结构的DOM与-OH的反应能力,并进一步研究了DOM对一系列受到广泛关注、在环境中经常检出的OPs与·OH的反应的影响。本研究的结果与发现,可以为揭示自然水环境中DOM对·OH与OPs反应的影响及机制提供理论依据,也可以为以-OH为基础的高级氧化体系的设计提供参考。采用总有机碳分析仪、紫外-可见吸收光谱以及荧光激发-发射光谱(EEMs)对5种不同来源DOM与·OH的反应过程进行了表征,以考察DOM来源和类别对其与-OH反应的影响。结果表明,不同来源DOM与·OH的反应能力存在显著差异,陆源DOM比水源DOM表现出更强的反应能力。DOM与·OH的反应表现为准一级动力学,以DOC变化表征的矿化速率常数kDOC与DOM的芳香碳/脂肪碳(Caro/Cali)有较好的相关性,说明芳香性碳对DOM与OH的反应具有重要贡献。以光吸收参数Absave表征的衰减速率常数与kDOC也表现出良好的相关性。因来源与类别的差异,不同DOM不仅初始的三维荧光光谱EEMs)存在差别,而且·OH氧化过程中EEMs的变化也表现出显著的不同。本研究选取了9种不同类别和性质的OPs,考察了DOM对其与·OH反应的影响。研究发现,DOM存在会显著抑制-OH对OPs氧化的准一级速率常数(k'1OH),k'1OH被抑制高达62%-91%。对于具有较强疏水性的OPs, DOM还会显著影响其与·OH的二级反应速率常数(k2OH)。同一种腐殖酸LHA对7种OPs的k20H抑制程度与OPs的疏水性(logKOW)呈正相关。logKOW一般与DOM与OPs的结合常数(logKDOC)具有很好的相关性,说明DOM结合作用对·OH氧化OPs反应存在重要影响。不同种类DOM对疏水性有机物(HOCs)与·OH反应的影响不同。随着DOM浓度增加,HOCs的DOM结合态比例相对增多,抑制效应增强。不同H2O2浓度下,DOM对·OH与多环芳烃芘、菲反应的k'1OH的抑制程度没有显著差异。
[Abstract]:Dissolved organic matter (DOM) is a kind of mixed organic matter with complex structural components in the environment. Its functional groups are abundant and can change the environmental trend of pollutants by interacting with (OPs), an organic pollutant in the environment, through a variety of mechanisms. Because DOM itself can react with free radical and possibly affect the form of OPs in water by binding effect, thus affect the reaction of OPs with free radical. Hydroxyl radical (O work) is a kind of radical with strong oxidation ability. It not only exists widely in nature, but also is often used to remove OPs. in advanced oxidation system. In this study, H2O2 was used to produce -OH. Firstly, the reaction ability of DOM from different sources and structures with -OH was investigated, and the effect of DOM on a series of reactions between OPs and OH, which were widely concerned and frequently detected in the environment, was studied. The results and findings of this study can provide theoretical basis for revealing the effect and mechanism of DOM on the reaction between OH and OPs in natural water environment, and can also provide a reference for the design of advanced oxidation system based on -OH. The reaction process of DOM with OH from five different sources was characterized by total organic carbon analyzer, UV-Vis absorption spectrum and fluorescence excitation emission spectroscopy (EEMs) to investigate the effect of the source and type of DOM on the reaction with -OH. The results showed that there was significant difference in the reaction ability between DOM and OH from different sources, and the reaction ability of terrestrial DOM was stronger than that of source DOM. Dom and OH showed quasi-first-order kinetics. The mineralization rate constant kDOC, which is characterized by the change of DOC, has a good correlation with the aromatic carbon / fatty carbon (Caro/Cali) of DOM, which indicates that aromatic carbon plays an important role in the reaction between DOM and OH. The attenuation rate constant characterized by optical absorption parameter (Absave) also showed a good correlation with kDOC. Because of the difference of source and category, not only the initial three dimensional fluorescence spectra (EEMs) of different DOM are different, but also the changes of EEMs in the process of OH oxidation are obviously different. In this study, nine different types and properties of OPs, were selected to investigate the effect of DOM on the reaction with OH. It is found that the presence of Dom can significantly inhibit the quasi-first-order rate constant (k'1OH) of the oxidation of OPs by -OH up to 62-91. The second order reaction rate constant (k2OH) of OPs, DOM with strong hydrophobicity was also significantly affected. The degree of inhibition of k20H of seven OPs by the same humic acid LHA was positively correlated with the hydrophobic (logKOW) of OPs. LogKOW generally had a good correlation with the binding constant (logKDOC) of DOM and OPs, indicating that DOM binding has an important effect on OH oxidative OPs reaction. Different kinds of DOM have different effects on the reaction of hydrophobic organic compounds (HOCs) with OH. With the increase of DOM concentration, the proportion of DOM binding state of HOCs increased relatively, and the inhibitory effect was enhanced. There was no significant difference in the inhibition of k'1OH between OH and polycyclic aromatic hydrocarbons pyrene and phenanthrene at different concentrations of H2O2.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X505
本文编号：2202977
[Abstract]:Dissolved organic matter (DOM) is a kind of mixed organic matter with complex structural components in the environment. Its functional groups are abundant and can change the environmental trend of pollutants by interacting with (OPs), an organic pollutant in the environment, through a variety of mechanisms. Because DOM itself can react with free radical and possibly affect the form of OPs in water by binding effect, thus affect the reaction of OPs with free radical. Hydroxyl radical (O work) is a kind of radical with strong oxidation ability. It not only exists widely in nature, but also is often used to remove OPs. in advanced oxidation system. In this study, H2O2 was used to produce -OH. Firstly, the reaction ability of DOM from different sources and structures with -OH was investigated, and the effect of DOM on a series of reactions between OPs and OH, which were widely concerned and frequently detected in the environment, was studied. The results and findings of this study can provide theoretical basis for revealing the effect and mechanism of DOM on the reaction between OH and OPs in natural water environment, and can also provide a reference for the design of advanced oxidation system based on -OH. The reaction process of DOM with OH from five different sources was characterized by total organic carbon analyzer, UV-Vis absorption spectrum and fluorescence excitation emission spectroscopy (EEMs) to investigate the effect of the source and type of DOM on the reaction with -OH. The results showed that there was significant difference in the reaction ability between DOM and OH from different sources, and the reaction ability of terrestrial DOM was stronger than that of source DOM. Dom and OH showed quasi-first-order kinetics. The mineralization rate constant kDOC, which is characterized by the change of DOC, has a good correlation with the aromatic carbon / fatty carbon (Caro/Cali) of DOM, which indicates that aromatic carbon plays an important role in the reaction between DOM and OH. The attenuation rate constant characterized by optical absorption parameter (Absave) also showed a good correlation with kDOC. Because of the difference of source and category, not only the initial three dimensional fluorescence spectra (EEMs) of different DOM are different, but also the changes of EEMs in the process of OH oxidation are obviously different. In this study, nine different types and properties of OPs, were selected to investigate the effect of DOM on the reaction with OH. It is found that the presence of Dom can significantly inhibit the quasi-first-order rate constant (k'1OH) of the oxidation of OPs by -OH up to 62-91. The second order reaction rate constant (k2OH) of OPs, DOM with strong hydrophobicity was also significantly affected. The degree of inhibition of k20H of seven OPs by the same humic acid LHA was positively correlated with the hydrophobic (logKOW) of OPs. LogKOW generally had a good correlation with the binding constant (logKDOC) of DOM and OPs, indicating that DOM binding has an important effect on OH oxidative OPs reaction. Different kinds of DOM have different effects on the reaction of hydrophobic organic compounds (HOCs) with OH. With the increase of DOM concentration, the proportion of DOM binding state of HOCs increased relatively, and the inhibitory effect was enhanced. There was no significant difference in the inhibition of k'1OH between OH and polycyclic aromatic hydrocarbons pyrene and phenanthrene at different concentrations of H2O2.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X505
【参考文献】
相关硕士学位论文 前1条
1 王晓晨;溶解性有机质对两种典型雄性激素光解的影响[D];大连理工大学;2013年
，本文编号：2202977
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