双极性金属颗粒强化电化学法还原地下水硝酸盐的研究

发布时间：2018-06-02 19:10

本文选题：硝酸盐 + 电化学还原　；参考：《中国地质大学(北京)》2015年硕士论文

【摘要】：地下水是世界各国重要而又宝贵的资源,在人类生产生活中扮演着至关重要的角色。随着经济高速发展,过度的人类活动引发了地下水硝酸盐污染,成为世界所共同关注的环境问题。地下水中硝酸盐污染主要是由于氮肥的过度施用,还包括生活污水及工业废水的排放、污水灌溉、固体废弃物的淋滤下渗等。高浓度硝酸盐的地下水对人体健康有极大的潜在危害,故去除地下水中硝酸盐使其满足饮用水标准显得至关重要。电化学法去除地下水硝酸盐因具有处理周期短、环境友好以及投资成本低等优势而备受关注。然而,电化学方法在目前实际应用中存在能耗高、处理量少等问题,使其大规模的推广和应用受到了限制。本研究基于电化学法还原地下水中硝酸盐的理论,以Ti板为阴极,Ti/Ir O2-Pt为阳极,并向电化学系统中加入金属颗粒,建立双极性金属颗粒强化电化学系统。研究目的在于探讨Na Cl投加量、电流密度以及金属颗粒材料对金属颗粒强化电化学系统的影响,确定强化系统的最佳运行参数;通过比较不同金属颗粒填充方式下系统性能差异,揭示双极性金属颗粒的工作机理并验证其强化作用,深入阐述双极性金属颗粒强化电化学系统对地下水硝酸盐的去除机理,为金属颗粒强化电化学系统去除地下水中硝酸盐的实际应用提供理论基础。结果表明,Na Cl投加量为0.5 g/L,电流密度为20 m A/cm2为双极性金属颗粒强化电化学系统的最佳运行条件,Cu-Zn颗粒为该系统的最适填充材料。在此条件下,硝酸盐去除率为93.94%,能量损耗为58.60 k Wh/n-NO3--N,氮气选择性为80.43%。同时,验证了金属颗粒对电化学系统去除硝酸盐的强化作用,金属颗粒的添加使系统硝酸盐去除率提高了62.36%~78.9%,能量损耗减少3~5倍。通过比较不同金属颗粒填充方式下的系统性能发现,金属颗粒发生极化后,形成多个微小而又独立的电解池,在阴极半球表面发生还原反应,同时在阳极半球表面发生氧化反应,提供更多的反应表面,有效提高硝酸盐的去除速率和电流利用率,降低能量损耗,对电化学系统起到强化作用。同时,硝酸盐的还原和还原副产物的氧化也分别发生在阴极和阳极表面。
[Abstract]:Groundwater is an important and valuable resource in the world and plays a vital role in human production and life. With the rapid development of economy, excessive human activities have caused nitrate pollution in groundwater, which has become a common environmental problem in the world. Nitrate pollution in groundwater is mainly due to the excessive application of nitrogen fertilizer, including the discharge of domestic sewage and industrial wastewater, sewage irrigation, leaching and infiltration of solid waste, etc. The groundwater with high nitrate concentration has great potential harm to human health, so it is very important to remove nitrate from groundwater to meet the drinking water standard. Electrochemical removal of nitrate from groundwater has attracted much attention due to its advantages of short treatment period, environmental friendliness and low investment cost. However, the application of electrochemical method is limited because of its high energy consumption and low treatment capacity. Based on the theory of electrochemical reduction of nitrate in groundwater, Ti plate was used as cathode and Ti / ir O2-Pt as anode, and metal particles were added to electrochemical system to establish bipolar metal particle enhanced electrochemical system. The purpose of this study is to investigate the effects of NaCl dosage, current density and metal particle material on the electrochemical system strengthened by metal particles, and to determine the optimal operating parameters of the strengthening system. By comparing the system performance differences under different metal particle filling modes, the working mechanism of bipolar metal particles was revealed and its strengthening effect was verified, and the mechanism of nitrate removal from groundwater by electrochemical enhanced electrochemical system with bipolar metal particles was discussed in depth. It provides a theoretical basis for the practical application of metal particle enhanced electrochemical system to remove nitrate from groundwater. The results show that the best operation conditions of bipolar metal particle enhanced electrochemical system are the dosage of NaCl 0.5 g / L and the current density of 20 m A/cm2. The Cu-Zn particles are the most suitable filling materials for the system. Under these conditions, the removal rate of nitrate is 93.94 and the energy loss is 58.60k / n-NO3-N, and the selectivity of nitrogen is 80.43. At the same time, the enhancement effect of metal particles on the removal of nitrate in electrochemical system was verified. The removal rate of nitrate in the system was increased by 62.36 and 78.9, and the energy loss was reduced by 3 ~ 5 times with the addition of metal particles. By comparing the system performance of different metal particle filling methods, it is found that after the polarization of the metal particles, a number of small and independent electrolytic cells are formed and the reduction reaction takes place on the surface of the cathode hemisphere. At the same time, oxidation reaction takes place on the surface of the anode hemisphere to provide more reactive surfaces, which can effectively improve the removal rate of nitrate and current utilization, reduce the energy loss, and strengthen the electrochemical system. At the same time, the reduction of nitrate and the oxidation of reductive by-products also occur on the cathode and anode surface, respectively.
【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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