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题名: UV/H2O2降解水中医药类污染物的动力学与反应途径研究
作者: 袁芳
学位类别: 博士
答辩日期: 2010
授予单位: 中国科学院研究生院
授予地点: 北京
导师: 胡春
关键词: 医药与个人护理品 ; UV/H2O2 ; 反应动力学 ; 模型预测 ; 毒性
中文摘要:
      医药与个人护理品(PPCPs)广泛存在于地表水、地下水、饮用水、污泥和土壤等环境介质中,这类新型微污染物在环境中将长期存在,常规的水净化工艺又很难将其去除,污染不可避免,势必会危害到人类的健康。新的水处理技术的研究与应用,意义重大。UV/H2O2是一种能有效去除水中有机污染物的高级氧化技术,在饮用水和再生水的处理中已有应用。在实际工程应用中,所涉及到的下列问题,如水体中的NOM、NO3-、碱度等对污染物降解效率的影响,反应产物的生成与毒性的变化等,已引起了关注。本文的主要研究目的是建立适用于UV/H2O2体系,目标污染物降解的反应动力学模型;明确该体系中目标污染物降解、总有机碳(TOC)去除、物质毒性变化三者的关系,以及溴酸盐(BrO3-)副产物的生成情况。为UV/H2O2体系应用于含新型微污染物水体的处理,提供理论指导。 本文选取了7种常见于水环境中的医药类污染物(PhACs)作为研究对象,分别在超纯水(UW)、北京密云水库原水(SW)、北京第九自来水厂砂滤池出水(DW)以及北京高碑店污水处理厂二沉池出水(WW)中,进行UV/H2O2降解实验。7种PhACs分别是消炎止痛剂布洛芬(IBU)、安替比林(PZ),抗组胺剂苯海拉明(DP),抗癫痫药苯妥英(PHT),四环素类抗生素土霉素(OTC)、多西环素(DTC),以及喹诺酮类抗生素环丙沙星(CIP)。研究内容与结果如下: (1)研究了7种PhACs的UV直接光降解和UV/H2O2氧化降解的动力学,证实了两种工艺条件下PhACs的降解都符合拟一级反应动力学规律;测得了PhACs的摩尔消光系数(ε254nm)与光量子产率(f254nm)等参数;根据竞争动力学方法,求得了各PhACs与羟基自由基(·OH)的二级反应速率常数(kOH/PhACs)。阐明了污染物的UV直接光解与·OH氧化降解的竞争机制。 (2)针对实际水体中存在着的大量·OH焠灭剂对UV/H2O2工艺处理效率产生的影响,引入了ROH,UV概念。ROH,UV即单位紫外剂量,·OH的生成量;它是通过研究UV/H2O2体系,对氯苯甲酸(pCBA)在不同水体中的降解动力学而建立。利用ROH,UV,得到水体中各·OH焠灭剂的总的焠灭效应( ,S表示·OH焠灭剂的浓度,kOH/S表示·OH焠灭剂与·OH的二级反应速率常数), 由此可建立涵盖实际水体中·OH焠灭剂影响的,适用于UV/H2O2体系目标污染物降解的动力学速率常数预测模型。进而研究UV/H2O2体系,PhACs在3种不同水体(SW、DW、WW)中的降解动力学,对此模型进行验证;发现其能够较好实现污染物在不同水体中降解速率常数的有效预测。 (3)研究了UV/H2O2氧化降解PhACs的过程,考察了原始物降解、总有机碳(TOC)去除及生物毒性变化三者的关系,发现 IBU、OTC、DTC、CIP 4种PhACs能在较短时间内降解完全;且随着PhACs的快速降解,物质的生物毒性效应迅速减弱直至完全脱毒。但是PhACs降解过程中TOC去除缓慢,污染物的彻底矿化较难实现。研究结果证实污染物的脱毒比其矿化更易实现。 在工程应用中,生物毒性指标是影响UV/H2O2体系最佳反应时间的主要因素。 (4)研究了UV/H2O2处理含溴离子(Br-)水质,溴酸盐(BrO3-)副产物生成的可能性。H2O2的还原性以及UV对BrO3-光分解作用,阻断了Br-氧化生成BrO3-的途径,该处理工艺不存在溴酸盐副产物生成的风险。
英文摘要:       Trace amount of pharmaceutical and personal care products (PPCPs) has been detected in different compartments, e.g. surface water, ground water, drinking water, sewage, and soil, in many countries. These emerging micropollutants show a wide range of persistence in aquatic environments, and some of them are highly persistent. In addition, it could not be removed effectively by conventional water and wastewater treatment processes. In such cases, PPCPs would potentially impact ecosystem and human health. It is meaningful for the study on advanced treatment technologies for the removal of PPCPs. UV/H2O2 process, one of the UV-based advanced oxidation processes, is recognized as an effective waste water treatment technology in the degradation of organic micropollutants, and has been applied in the treatment of drinking water and reclaimed water. The studies on the influence of NOM, NO3-, and alkalinity on the treatment efficiency, the by-products formation, and the toxicity changes are very important in the practical application of UV/H2O2 process. The principal objectives of this research were to predict the degradation of target compounds, using mathematical model, to study the relationships among the degradation of target compound, the removal of TOC, and the toxity changes, and to investigate the formation of BrO3- in UV/H2O2 process. Seven pharmaceuticals (PhACs) were slected in this research, due to their high usage and presence in aquatic environments, which were ibuprofen (IBU), phenazone (PZ), diphenhydramine (DP), phenytoin (PHT), oxytetracycline (OTC), doxycycline (DTC), and ciprofloxacin (CIP). Direct and indirect photolysis of the selected PhACs were investigated in buffered ultrapure water (UW), local surface water (SW), and treated water from local municipal drinking water treatment plant (DW) and wastewater treatment plant (WW). The main results obtained are as follows: (1) Pseudo-first-order kinetics was observed for all of the seven selected PhACs, in both direct UV photolysis and UV/H2O2 process. In these experiments, the molar absorption coefficient (ε254nm) and quantum yields (f254nm) of PhACs were obtained, as well as the second-order rate constant of ·OH with the selected PhACs (kOH/PhACs). In the degradation of PhACs in UV/H2O2 process, there was a competitive reaction between the direct UV photolysis and the oxidation of ·OH. (2) The ·OH radical scavengers existing in water matrices affected the treatment efficiency of UV/H2O2 significantly. In this study, ROH, UV, which was defined as the experimentally determined ·OH radical exposure per UV fluence, and determined by examing the destruction of a probe compound, para-chlorobenzoic acid (pCBA) in water matrices, was utilized to calculate the overall effect of ·OH radical scavenging ( ) in SW, DW, and WW. Moreover, a mathematical model coupled by this scavenging contribution was obtained, to predict the oxidation rate constant of target compound in UV/H2O2 process. For the verification of this mathematical model, degradation kinetics of PhACs in SW, DW, and WW in UV/H2O2 process was investigated. Results showed that the oxidation rate constants of PhACs in these three water matrices were predicted well. (3) In UV/H2O2 process, IBU, OTC, DTC, and CIP, all of the four selected PhACs were completely degraded fastly, and with the decay of PhACs, toxicity decreased. While in this process, TOC was removed slowly. It was difficult for total mineralization of the selected PhACs. Detoxification was much easier than mineralization, so the optimal time for the degradation of pollutants in UV/H2O2 process would be determined by toxicity changes. (4) In UV/H2O2 process, when using bromine (Br-) as starting compound, bromate (BrO3-) formation does not occur, for the reduction of H2O2 and the photodegradation of BrO3- in direct UV photolysis.
内容类型: 学位论文
URI标识: http://ir.rcees.ac.cn/handle/311016/35019
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:
袁芳. UV/H2O2降解水中医药类污染物的动力学与反应途径研究[D]. 北京. 中国科学院研究生院. 2010.
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