三维电极微生物燃料电池高级氧化水中对硝基苯酚研究

发布时间：2018-02-24 16:48

本文关键词： 三维电极微生物燃料电池过氧化氢高级氧化对硝基苯酚　出处：《天津大学》2015年博士论文　论文类型：学位论文

【摘要】：水中难降解有机污染物的有效去除是环境领域研究的热点,并且能源短缺问题促使清洁的工程技术研发成为紧迫的课题。本文构建新型三维电极微生物燃料电池(MFC),通过对氧还原阴极的研究将MFC从产电装置转变为生产过氧化氢的反应器,并引入微生物电解电池的概念,达到增加过氧化氢产量的目的;并在此基础上,通过外加或负载铁离子的方式构建三维电极MFC-Fenton系统,处理水中对硝基苯酚(PNP)污染,实现阳极室和阴极室同步处理有机废水。主要研究内容和结果如下:制备碳-PTFE颗粒电极用于MFC阴极生产过氧化氢,实验证明其是有效的阳极有机物降解和阴极过氧化氢制备的系统。石墨-PTFE颗粒电极MFC(MFC-GPEs)在过氧化氢制备性能上有很好的表现,但产电性能较差。MFC-GPEs在相对较高的电流密度下运行24 h后,过氧化氢浓度达到196.50mg·L~(-1),COD去除率为84%。在MFC-GPEs外加电压,对其阳极COD去除性能和阴极过氧化氢产量提高具有积极的影响。但是,过高的电压将引起阴极副反应产生氢气降低过氧化氢的产量。综合考虑过氧化氢产量,MFC电流效率和阳极COD去除率,最佳外加电压是0.4 V。此时,MFC在外电阻10Ω下运行8 h,以2.12 kg·m-3·day~(-1)的生产速率生产过氧化氢705.6 mg·L~(-1)。生产1 kg过氧化氢输入的能量为0.659 kWh。在MFC-GPEs阴极外加亚铁离子构建MFC-Fenton系统,由于PNP被吸附在颗粒电极的表面增加了其反应机会从而提高了PNP去除效率。较低的阴极液初始pH值,中等的亚铁离子投加量以及较小的外电阻更有利于该系统降解水中PNP。当系统在初始PNP浓度50 mg·L~(-1),亚铁离子投加量0.025 mol·L~(-1),pH为3和外电阻为20Ω的最佳参数下运行8 h,PNP降解率达到了95.7%。系统运行9个周期,其PNP降解率均可稳定在90%并能够持续输出电能。在GPEs表面负载铁氧化物制备复合电极(FO/GPEs),使用复合电极的MFC系统具有较佳的产电性能、原位电化学制备H2O2能力和催化Fenton反应能力,且表现出中性条件下运行的可行性。在中性条件下,PNP降解率(8 h)和TOC去除率(64 h)均达到85%左右。该系统的降解机理是典型Haber Weiss机理和表面异相催化反应的结合。
[Abstract]:The effective removal of refractory organic pollutants in water is a hot topic in the field of environment. The problem of energy shortage makes the research and development of clean engineering technology urgent. In this paper, a new type of three-dimensional electrode microbial fuel cell (MFCs) is constructed, and the oxygen reduction cathode is studied to transform MFC from an electric device to a reactor for producing hydrogen peroxide. The concept of microbial electrolytic battery was introduced to increase the production of hydrogen peroxide, and on this basis, a three-dimensional electrode MFC-Fenton system was constructed by adding or loading iron ions to treat the pollution of p-nitrophenol in water. The main research contents and results are as follows: preparation of carbon-PTFE particle electrode for MFC cathode to produce hydrogen peroxide. It is proved by experiments that it is an effective system for anodic organic degradation and cathodic hydrogen peroxide preparation. The graphite PTFE particle electrode MFCMFC-GPEs has a good performance in the preparation of hydrogen peroxide. However, after running at a relatively high current density for 24 hours, the hydrogen peroxide concentration reached 196.50 mg 路L ~ (-1) and the removal rate of hydrogen peroxide was 84%. Under the applied voltage of MFC-GPEs, it had a positive effect on the removal performance of anode COD and the increase of hydrogen peroxide production at cathode. If the voltage is too high, hydrogen will be produced in the cathode side reaction to reduce the hydrogen peroxide production. Considering the hydrogen peroxide output, the current efficiency of the MFC and the removal rate of the anode COD will be taken into account. The optimum applied voltage is 0.4 V. at this time, the hydrogen peroxide is 705.6 mg 路L ~ (-1) 路L ~ (-1) hydrogen peroxide is produced at the production rate of 2.12 kg 路m ~ (-3) 路d ~ (-1) at an external resistance of 10 惟 for 8 h. The input energy of producing 1 kg hydrogen peroxide is 0.659 kWh. the MFC-Fenton system is constructed by adding ferrous ions to the MFC-GPEs cathode. Because PNP is adsorbed on the surface of the particle electrode, the reaction chance is increased and the removal efficiency of PNP is improved. When the initial concentration of PNP was 50 mg 路L ~ (-1), the dosage of Fe ~ (2 +) was 0.025 mol 路L ~ (-1) (pH = 3) and the external resistance was 20 惟, the system could degrade PNPs for 8 h. The system runs for 9 cycles. The PNP degradation rate of the composite electrode is stable at 90% and the electric energy can be continuously produced. The MFC system using the composite electrode has better electrical properties, in situ electrochemical preparation of H _ 2O _ 2 and catalyzing the Fenton reaction, when the composite electrode is prepared by iron oxide on the surface of GPEs. Under neutral conditions, the degradation rate of PNPs and the removal efficiency of TOC reached about 85%. The degradation mechanism of the system is the combination of typical Haber Weiss mechanism and surface heterogeneous catalytic reaction.
【学位授予单位】：天津大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TM911.45

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