【作者】 李斌；

【导师】 杨胜科； 程东会；

【作者基本信息】 长安大学 ， 建筑与土木工程（专业学位）， 2013， 硕士

【摘要】 近年来随着经济及工农业的快速发展，地下水污染也越来越严重。硝酸盐氮已成为进入水体最频繁的污染物之一，且污染具有日益恶化的趋势，地下水硝酸盐氮污染已成为全世界关注的热点。由于硝酸盐氮污染的危害性及紧迫性，地下水硝酸盐氮的去除技术研究成为一个热点。纳米材料具有比表面积大，活性强等特点，能够快速的去除有机物、硝酸盐及重金属等污染物，因而受到更多研究者的关注，纳米技术的发展为地下水处理提供了更多的研究思路。已有研究表明，纳米铁对硝酸盐氮有较高的去除率，但还原产物主要为氨氮，生成率高达90%以上，且初始反应速率不是很高，不能很好的适应高浓度硝酸盐氮去除。因此，开展地下水硝酸盐氮污染治理理论与技术方法研究，探讨高效简便的地下水硝酸盐氮处理方法，仍然是地下水污染治理研究工作的重要内容，具有重要的理论价值和现实意义。因此本文以石墨烯为载体，采用液相还原法将纳米铁负载于石墨烯上，然后进行去除硝酸盐的静态实验，在比较研究还原铁粉、纳米铁与石墨烯负载纳米铁去除能力的基础上，深入研究了石墨烯负载量、硝酸盐氮初始浓度、pH、溶解氧和共存离子等因素对去除效果的影响，探讨了石墨烯负载纳米铁去除硝酸盐的反应机理。论文的主要研究结论如下：（1）还原铁粉在中性条件下基本不与硝酸盐反应，只有在较低pH条件下才对硝酸盐氮有较好的去除效果；纳米铁在中性条件下即能较好的去除硝酸盐氮，90分钟去除率即能达到80%以上，当硝酸盐氮初始浓度为50mg/L时，纳米铁去除硝酸盐氮反应符合一级反应动力学方程。（2）石墨烯负载纳米铁去除硝酸盐氮效率明显高于纳米铁，且氨氮生成率为79%左右，较之纳米铁有所降低。石墨烯与纳米铁最佳负载比为5：1；在石墨烯负载纳米铁投加量相同情况下，随着硝酸盐氮初始浓度的增大，去除率有所下降；较低pH，能够不同程度的提高去除率，主要是因为较低pH能够及时更新石墨烯负载纳米铁反应面；水中溶解氧浓度越大，石墨烯负载纳米铁对硝酸盐氮去除效率越低，这是因为溶解氧氧化纳米铁，降低了还原硝酸盐氮的能力；共存离子Cl-、SO₄^2-、PO₄^3-对去除硝酸盐氮效果均有影响，影响程度由大到小依次为：PO4_<sup>3-、SO₄^2-、Cl^-。（3）通过对石墨烯负载纳米铁与硝酸盐反应0、30、90分钟后剩余物进行SEM研究发现，制备的纳米铁为颗粒状球体，直径为20⁸0nm，随着反应的进行，颗粒状的纳米铁逐渐被消耗，变成絮状物；经动力学研究表明，石墨烯负载纳米铁与硝酸盐的反应级数n=0.45，表明该反应不是一个简单的一级化学反应，而是一个由化学反应、吸附/解吸等的组成的复杂过程。更多还原

【Abstract】 In recent years, with the rapid development of economy, industry and agriculture,groundwater pollution is becoming more and more serious. Nitrate nitrogen has become oneof the most frequent contaminants to enter the body of water, which becomes more and moreserious. Groundwater nitrate nitrogen pollution and removal of technical studies have becomethe focus of attention around the world. Nano-materials can remove organics, nitrates, heavymetals and other pollutants quickly, with the feature of being active and with large surfacearea. Therefore, subject with more attention from researchers and the development ofnanotechnology provides more research ideas for groundwater treatment. Studies have shownthat nanoscale iron nitrate nitrogen has higher removal rate, but it still has many problems.For example, it has a reduction product ammonia generation rate of more than90%, the initialreaction rate is not high and it can’t treat the high concentration of nitrate nitrogen effectively.Therefore, to carry out groundwater nitrate nitrogen pollution control theory and technologymethods, study on an efficient and simple approach for groundwater nitrate nitrogen is still animportant content of the groundwater pollution control. It has an important theoretical andpractical significance.In this paper, we take liquid phase reduction method and load Nanoscale iron in graphenand then have static experiments. We compared the study of reduced iron powder, ironnano-graphene, load nanoscale iron removal capacity on the basis of removal capacity. Weexplore graphene load, initial concentration of nitrate nitrogen, initial pH, dissolved oxygenand ions on the removal, the graphene load nanoscale iron nitrate removal reactionmechanism, and analysis of various factors that affect the removal rate. The main researchresults are as follow：（1）The iron powder under neutral conditions with nitrate does not react actually. Itworks well only in the lower pH conditions. Nano-iron under neutral conditions can be abetter removal of nitrate nitrogen and remove rate is able to achieve more than80%within90minutes. When the initial concentration of Nano-iron is about50mg/L, nitrate nitrogen removal reaction is equivalent to first-order kinetics equation.（2）Using Graphene load nanoscale iron to remove the nitrate nitrogen was significantlyhigher than nano-iron, and the ammonia generated rate is about79%only, which is a littlelower than Nano-iron. When the Load ratio of Graphene with nanoscale iron reaches5:1, itwill be the best. With the increase of initial concentration of nitrate nitrogen, lower initial pH,the degrees of removal rate can be proved to vary, mainly because lower pH can update theload of graphene nano-iron reaction sites. The greater of the concentration of dissolvedoxygen in the water, the lower the nitrate nitrogen removal efficiency will be, which isbecause the dissolved oxygen nanoscale iron oxide decrease the ability to reduce nitratenitrogen; The coexisting ions Cl-、SO₄^2-、PO₄^3-also have an impact on the removal effect ofnitrate nitrogen, the impact in descending order: PO4_<sup>3-、SO₄^2-、Cl^-.（3）It can be obtained by SEM study of reaction residues about0,30,90minutes, Theparticle size of nanocrystalline iron for20to80nm, As the reaction proceeds, the nanoparticulate iron is gradually consumed, and it becomes floc.; Kinetic studies have shown thatgraphene load nanoscale iron and nitrate reaction order is about0.45which means thereaction is not a simple first-order reaction, but rather a set of redox reactions and adsorptionprocess for the integration of complex reactions.更多还原