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Technology Research of Graphene Supported Nanometer Iron Removal of Nitrate Nitrogen in Groundwater

Author: LiBin
Tutor: YangShengKe
School: Chang'an University
Course: Architecture and Civil Engineering
Keywords: graphene load iron nanoparticles nano-iron groundwater nitrate nitrogen removal rate
CLC: X523
Type: Master's thesis
Year: 2013
Downloads: 36
Quote: 0
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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-、SO42-、PO43-also have an impact on the removal effect ofnitrate nitrogen, the impact in descending order: PO4<sup>3-、SO42-、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.

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CLC: > Environmental science, safety science > Environmental pollution and its prevention > Water pollution and its control > Groundwater
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