纳米铁铜去除地下水中硝酸盐的实验研究

发布时间：2018-01-06 22:29

  本文关键词：纳米铁铜去除地下水中硝酸盐的实验研究　出处：《中国海洋大学》2015年硕士论文　论文类型：学位论文

  更多相关文章： 纳米铁铜 硝酸盐去除 无机阴离子 运移沉积

【摘要】：随着工业和农业的迅速发展,近些年硝酸盐已成为许多国家地下水中的常见污染物,并且污染日益严重。作为一种新的污染控制技术,将纳米零价铁及其复合材料应用于地下水硝酸盐污染修复,表现出了非常明显的优势,已成为环境研究热点方向。地下水成分复杂,共存离子对纳米铁系材料去除硝酸盐的影响目前没有系统的研究,而且比较贴近于实际地下水环境的砂柱、砂槽实验还很少,纳米颗粒在砂柱中的迁移沉积,以及对污染物的去除规律仍然不甚了解,因而非常有必要考虑地下水的实际水化学条件和水动力条件,对纳米铁系材料去除硝酸盐开展系统的砂柱、砂槽实验研究。基于上述考虑,本文采用液相还原法制备了纳米级Fe/Cu金属复合材料,采用TEM分析手段对纳米材料的结构进行了表征,并且将其用于硝酸盐污染物的去除。首先研究了初始硝酸盐浓度对硝酸盐去除的影响,确定了纳米铁铜的最佳投加量;在此基础上,考察了Cl", SO42-,HCO3和PO43-四种无机阴离子在纳米Fe/Cu颗粒投加不足和足量条件下对硝酸盐的去除以及还原产物的影响。另外,研究了富里酸,溶解氧对纳米Fe/Cu颗粒还原硝酸盐过程的影响。开展了纳米Fe/Cu双金属的砂柱注入实验研究,分析了石英砂粒径,纳米颗粒浓度和纳米颗粒体积对纳米颗粒迁移影响,以及石英砂粒径,纳米颗粒浓度,纳米颗粒体积和初始硝酸盐浓度对硝酸盐在砂柱中去除的影响。主要结论有以下几点：(1)纳米Fe/Cu足量时,硝酸盐被彻底还原,产物只有氨氮：纳米Fe/Ca不足时,硝酸盐不能被全部还原,产物为氨氮和亚硝酸盐。(2)当纳米颗粒的投加足量时,Cl-, SO42-, HCO3和PO43-对硝酸盐的去除均起到抑制作用,由大到小依次为：PO43SO42-HCO3-Cl-。其中P043-的作用几乎不受P043-浓度的影响,而SO42-,HCO3和C1-三种离子浓度越大,抑制作用越强。另外,SO42-,HCO3-和C1-对氨氮的生成有促进作用,由大到小依次为：SO42-HCO3-Cl-,且浓度越大,促进作用越强。原因是,P043-通过吸附作用占据铁表面的活性点位从而抑制硝酸盐还原;Cl-, SO42-, HCO3-与Fe(Ⅱ), Fe(Ⅲ)和OH-形成绿锈,可以促进硝酸盐还原成氨氮,从而增大氨氮在产物中的比例,进而降.低硝酸盐的去除率。当纳米铁铜投加足量时,SO42和HCO3-抑制硝酸盐和中间产物亚硝酸盐的还原,其作用大小顺序为：HCO3-SO42-,且浓度越大,作用越强,原因是,Fe(Ⅱ), Fe(Ⅲ)和OH-在SO42-或HCO3-的参与下形成了绿锈,而Cl促进了硝酸盐的还原,可能是因为Cl-与Fe(Ⅱ)/Fe(Ⅲ)发生络合作用,降低了铁的氧化产物在纳米颗粒上的沉积,从而提高了NO3-和NO2-与纳米颗粒的接触。(3)富里酸降低了纳米铁铜对硝酸盐的还原速率,对其去除率没有影响。而溶解氧降低了纳米铁铜对硝酸盐的还原速率和去除率。(4)纳米铁铜双金属颗粒在砂柱中的截留分布情况随介质粒径,颗粒浓度和颗粒体积的不同而不同,但均在砂柱的前半部分分布较多,离出口端愈近截留量愈小。纳米铁铜颗粒对硝酸盐的还原过程中,随着研究因素的不同,NO3--N,NH4+-N, NO2--N以及总氮的变化趋势相同。取样开始,因为纳米颗粒对硝酸盐的吸附作用,使得NO3--N和总氮量为零,随即被吸附的硝酸盐开始发生还原反应,因为纳米颗粒足量,所以产物只有氨氮,随着反应进行,纳米颗粒活性降低,NO3--N和NO2--N出现,同时氨氮量下降。NO3--N浓度随时间不断增大,NO2--N浓度先增大到最大浓度后下降,说明纳米颗粒已逐渐失去对硝酸盐的还原能力。(5)砂柱中介质粒径影响纳米铁铜双金属颗粒的迁移,粒径越大,越有利于纳米颗粒的迁移,但是介质粒径对硝酸盐的去除效果没有影响。纳米颗粒的注入体积对纳米颗粒在砂柱中的分布规律没有影响,但是注入体积越大,截留在砂柱中纳米颗粒的量越多,所以越有利于硝酸盐的还原。纳米颗粒的注入浓度越大,越有利于纳米颗粒的迁移,对硝酸盐的去除效果越佳。初始硝酸盐浓度越大,纳米颗粒维持反应活性的时间越短。
[Abstract]:With the rapid development of industry and agriculture in recent years, nitrate has become common in many countries of pollutants in groundwater, and pollution is becoming increasingly serious. As a new pollution control technology, nano zero valent iron and composite materials used in groundwater nitrate pollution remediation, showed very obvious advantages, has become a hot research environment the direction of groundwater. Complex components and coexisting ions on the effect of nano ferric nitrate removal material there is no system, and relatively close to the actual sand column groundwater environment, sand tank experiment is less, migration and deposition of nanoparticles in the sand column, and the pollutant removal law is still not fully understood, so it is necessary to consider the actual Groundwater Hydrochemical conditions and hydrodynamic conditions, the nanometer iron material on nitrate removal in sand column system, sand tank experiments. Based on the research The above considerations, this paper adopts liquid Fe/Cu nano metal composite material was prepared by reduction, by means of TEM analysis of nano materials were characterized, and used for the removal of nitrate pollutants. Firstly, the initial nitrate concentration on the nitrate removal effect, determine the best dosage of nano iron and copper add amount; on this basis, the effects of Cl, SO42-, and the effect on removal of nitrate reduction products of HCO3 and PO43- four kinds of inorganic anions and lack sufficient conditions in adding nano Fe/Cu particles. In addition, the study of fulvic acid, dissolved oxygen reduction effect of nitrate on the process of nano Fe/Cu particles. The sand column nano Fe/Cu double metal injection experiment, quartz sand particle size analysis, effects of the concentration of the nano particles and nano particle volume on migration of nanoparticles, and quartz sand particle size, particle concentration, particle Effect of volume and initial nitrate concentration on the removal of nitrate in the sand column. The main conclusions are as follows: (1) a sufficient amount of nano Fe/Cu, nitrate was completely restored, the only product of ammonia: nano Fe/Ca is insufficient, the nitrate can not be reduced completely, is the product of ammonia and nitrite (2.) when the nano particles added enough, Cl-, SO42-, HCO3 and PO43- on the removal of nitrate have played an inhibitory effect, from large to small is as follows: PO43SO42-HCO3-Cl-. the effect of P043- was not affected by the concentration of P043- and SO42-, HCO3 and C1- three kinds of ion concentration, inhibition stronger. In addition, SO42-, HCO3- and C1- to promote the production of ammonia, from large to small is as follows: SO42-HCO3-Cl-, and the higher the concentration, the stronger the effect of promoting. The reason is that the adsorption of P043- by occupying the active iron surface to point inhibition of nitrate reduction; Cl-, SO42-, HCO3-涓嶧e(鈪，

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