纳米零价铁芬顿体系降解三氯乙烯实验研究

发布时间：2018-05-15 02:35

本文选题：纳米零价铁 + 壳-核结构　；参考：《中国地质大学(北京)》2015年硕士论文

【摘要】：随着经济的快速发展和人口的急剧增长,人类生活和生产过程中对地下水资源的需求量也不断增长。与此同时,在地下水的大量开发和利用过程中不可避免会遇到污染问题,其中三氯乙烯作为典型氯代有机污染受到人们的特别关注。近年来,研究者发现纳米零价铁可以应用于原位环境修复,由于纳米零价铁较大的比表面积和较高的反应活性,相比于传统的零价铁颗粒,纳米颗粒表现出更高的降解速率和更少的反应副产物。纳米零价铁颗粒在接触空气、水后会快速形成铁氧化物、铁氢氧化物的外壳,这种天然的壳-核结构在一定程度上降低了纳米零价铁的活性,但是其外壳可以提供Fenton氧化法所需要的二价铁和三价铁来源,因此壳-核结构的纳米零价铁作为Fenton体系的多相催化剂进行原位环境修复具有一定的潜力。本论文使用壳-核结构纳米零价铁作为Fenton体系的催化剂,在中酸性条件下,进行高浓度三氯乙烯降解实验,同时选择苯甲酸作为化学探针捕获Fenton体系产生的羟基自由基,通过XRD、TEM、XPS等表征手段,考虑到初始p H值对Fenton体系的影响,对比纳米磁铁矿的Fenton体系,探讨壳-核结构纳米零价铁的Fenton体系氧化降解TCE的反应机理,为纳米零价铁的Fenton体系应用于原位环境修复的场地试验以及实际污染修复提供了重要的理论基础和实际应用参考。本论文主要研究成果如下:(1)在中酸性条件下,壳-核结构纳米零价铁的Fenton体系可以对高浓度TCE进行高效、完全的氧化降解。(2)以苯甲酸作为化学探针,发现壳-核结构纳米零价铁的Fenton体系主要以产生强氧化性的羟基自由基对TCE进行氧化降解。(3)初始p H条件影响Fenton体系的氧化能力,酸性p H条件强于中性p H条件,且壳-核结构纳米零价铁有利用扩展Fenton体系的p H值适用范围。(4)壳-核结构纳米零价铁在Fenton体系中主要作为固体催化剂进行多相催化反应,外壳Fe3O4提供Fenton催化反应必需的Fe2+和Fe3+来源,内核Fe0提供电子加速Fenton链式催化反应的循环。相比于纳米磁铁矿,壳-核结构纳米零价铁的Fenton体系更适用于原位环境修复。
[Abstract]:With the rapid development of economy and the rapid growth of population, the demand for groundwater resources in human life and production process is also increasing. At the same time, pollution problems will inevitably be encountered in the development and utilization of groundwater, especially trichloroethylene as a typical chlorinated organic pollution. In recent years, researchers have found that nanocrystalline zero-valent iron can be used for in-situ environmental remediation. Due to its larger specific surface area and higher reactive activity, nano-zero-valent iron particles are more efficient than traditional zero-valent iron particles. Nanoparticles exhibit higher degradation rates and less byproducts. Nanocrystalline zero-valent iron particles will quickly form iron oxides, ferric hydroxide shells after contact with air, and this natural shell-core structure reduces the activity of nanoscale zero-valent iron to a certain extent. However, the shell can provide the bivalent and trivalent iron sources for the Fenton oxidation process. Therefore, the nano-zero-valent iron with shell-core structure can be used as a heterogeneous catalyst for the Fenton system for in situ environmental remediation. In this paper, the chi-core nanosized zero-valent iron was used as the catalyst for the Fenton system. The degradation of trichloroethylene was carried out under the medium acid condition. Benzoic acid was used as the chemical probe to capture the hydroxyl radical produced by the Fenton system. Considering the effect of initial pH value on Fenton system, compared with the Fenton system of nano-magnetite, the mechanism of oxidative degradation of TCE by Fenton system with shell core structure nano-zero valence iron was discussed. It provides an important theoretical basis and practical reference for the application of nano-zero-valent iron Fenton system in site tests of in-situ environmental remediation and the actual remediation of pollution. The main results of this paper are as follows: (1) in the presence of intermediate-acid conditions, the high concentration of TCE can be effectively degraded by Fenton system with zero-valence iron nanostructure, and benzoic acid is used as a chemical probe. It was found that the oxidation ability of TCE was affected by the initial pH condition of the Fenton system, which produced strongly oxidized hydroxyl radicals. The acidic pH condition was stronger than the neutral pH condition. In addition, nanocrystalline zero-valent iron with shell / core structure is mainly used as a solid catalyst for heterogeneous catalytic reaction in Fenton system by extending the pH value of Fenton system. The shell Fe3O4 provides the necessary Fe2 and Fe3 sources for the Fenton catalytic reaction, and the kernel Fe0 provides the electron accelerated Fenton chain reaction cycle. Compared with nanomagnetite, the Fenton system is more suitable for in situ environmental remediation.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X523

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