有机物强化电化学法去除地下水硝酸盐的研究

发布时间：2018-10-08 17:30

【摘要】：地下水是自然水文循环的重要组成部分,也是人类的一种重要饮用水源。近年来,随着工农业生产的迅速发展,大量含氮化肥的使用、生活污水和工业废水的不达标排放以及固体废弃物的淋滤下渗等导致地下水遭受到了严重的硝酸盐污染。长期饮用高含量硝酸盐氮的地下水将对人体健康产生严重的危害。因此,必须对其进行处理,以保证供水安全。与传统的物理化学以及生物处理技术相比,硝酸盐电化学具有效率高、投资成本低、操作简便、环境友好等优势。然而,目前电化学技术存在能耗高、电流效率低以及极板易钝化的问题,难以满足大规模的实际应用。因此,优化和改良传统的电化学体系,提高其性能是十分必要的。在硝酸盐电化学处理过程中,硝酸盐的还原速率主要受阴极材料的硝酸盐催化还原特性、阳极材料的氨氮氧化特性、电极板间距、电流密度、电解质性质等的影响。本研究主要研究了阴极材料、Na Cl浓度、电流密度和极板间距对硝酸盐还原的影响,并得出了最优的电化学还原硝酸盐条件:以Ti/Ir O2-Pt为阳极,Cu-Zn为阴极,极板间距为20 mm,电流密度为20 m A/cm2时,投加0.5 g/L Na Cl,1.5 g/L Na2SO4。在此条件下,硝酸盐的去除率达到72.1%,氨氮基本被氧化,出水中未检测到亚硝酸盐的存在。在本研究中,利用两种方法强化硝酸盐电化学去除效果:增强阴极的还原和抑制阳极的氧化。采用Ti/Ir O2-Pt阳极,Cu-Zn阴极,分别投加甲醇和水杨酸强化硝酸盐去除效果。电解甲醇,产生氢气,促进阴极还原。投加水杨酸,吸收羟基自由基,抑制阳极氧化。实验结果表明,投加0.0067 g/L的甲醇(100 mg/L COD),硝酸盐氮在180 min内,由50 mg/L降低到3.2 mg/L,硝酸盐的还原效率提高了16.5%;投加0.0316 g/L的水杨酸(20 mg/L COD),硝酸盐的还原速率提高了14.4%。尽管在反应过程中,投加了甲醇,以及产生了亚硝酸盐和氨氮等副产物,但最终被完全去除。综上,本研究能够提高地下水硝酸盐的去除效果,是一种高效的去除硝酸盐污染的方法。
[Abstract]:Groundwater is an important part of natural hydrological cycle and also an important drinking water source for human beings. In recent years, with the rapid development of industrial and agricultural production, the use of a large number of nitrogen-containing fertilizers, the discharge of domestic sewage and industrial wastewater, as well as the leaching and infiltration of solid wastes, the groundwater has been seriously polluted by nitrate. Drinking groundwater with high nitrate nitrogen for a long time will cause serious harm to human health. Therefore, it must be treated to ensure the safety of water supply. Compared with the traditional physical chemistry and biological treatment technology, nitrate electrochemistry has the advantages of high efficiency, low investment cost, simple operation and environmental friendliness. However, the current electrochemical technology has many problems, such as high energy consumption, low current efficiency and easy passivation of the electrode plate, so it is difficult to meet the practical application on a large scale. Therefore, it is necessary to optimize and improve the traditional electrochemical system and improve its performance. In the process of nitrate electrochemical treatment, the reduction rate of nitrate is mainly affected by the catalytic reduction characteristics of the cathode material, the characteristics of ammonia-nitrogen oxidation of the anode material, the electrode plate spacing, the current density and the electrolyte properties. The effects of Na Cl concentration, current density and plate spacing on nitrate reduction were studied in this paper. The optimal electrochemical reduction conditions of nitrate were obtained as follows: Ti/Ir O2-Pt as anode and Cu-Zn as cathode. When the plate spacing is 20 mm, and the current density is 20 m A/cm2, 0.5 g / L Na Cl,1.5 g / L Na2SO4. is added. Under these conditions, the removal rate of nitrate reached 72.1%, the ammonia nitrogen was basically oxidized, and no nitrite was detected in the effluent. In this study, two methods were used to enhance the electrochemical removal of nitrate: to enhance the reduction of the cathode and to inhibit the oxidation of the anode. The removal efficiency of nitrate was enhanced by adding methanol and salicylic acid into the Cu-Zn cathode of Ti/Ir O2-Pt anode. Electrolysis of methanol produces hydrogen and accelerates cathodic reduction. Add salicylic acid to absorb hydroxyl radical and inhibit anodic oxidation. The results showed that the reduction efficiency of 0.0067 g / L methanol (100 mg/L COD), nitrate nitrogen decreased from 50 mg/L to 3.2 mg/L, nitrate in 180 min) and 0.0316 g / L of salicylic acid (20 mg/L COD), nitrate) increased the reduction rate. Although methanol was added and nitrite and ammonia nitrogen were produced during the reaction, they were completely removed. In conclusion, this study can improve the removal effect of nitrate in groundwater, and it is an efficient method to remove nitrate pollution.
【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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