【作者】 朱晔；

【导师】 李健生；

【作者基本信息】 南京理工大学 ， 环境工程， 2012， 硕士

【摘要】 纳米零价铁(NZVI)具有粒径小、比表面积大、反应活性高的特点,在环境修复与治理领域受到人们的广泛关注。但是,NZVI面临的易团聚、易被氧化的缺点限制了其在实际中的广泛应用。因此,提高NZVI的稳定性、保持其活性是目前的研究热点之一。本文以有序介孔材料SBA-15作为载体负载NZVI增强其在空气中的稳定性,保持其活性,同时利用SBA-15的吸附性能来提高污染物的去除速率。采用等体积浸渍—焙烧—氢气还原法合成出一种集吸附和还原于一体的SBA-15负载NZVI复合材料(NZVI/SBA-15),通过X射线衍射(XRD)、透射电镜(TEM),氮气吸附/脱附等对材料进行结构表征。论文进一步考察了复合材料对水中微量硝基苯的吸附降解性能,讨论了不同反应条件对硝基苯降解效率的影响,并研究了硝基苯的反应途径及复合材料对硝基苯的降解机理。结果表明：(1)随着铁负载量的增加,复合材料的有序度逐渐减弱,比表面积、孔容孔径也逐渐降低,但仍保持介孔材料的特性。纳米铁以α-Fe0的形态均匀单一的分散在SBA-15的孔道内。未负载的NZVI团聚现象严重,粒径较大。(2)反应12h后,SBA-15、NZVI、NZVI/SBA-15复合材料对溶液中硝基苯的去除率分别为51.59%、56.01%、94.94%。复合材料对硝基苯较高的去除率归因于载体吸附和NZVI还原的协同作用。(3)溶液中硝基苯的去除率随着铁负载量及复合材料的投加量增加而提高,酸性条件有利于降解反应的进行,碱性条件阻碍反应的进行,随着溶液初始浓度的逐渐增大,硝基苯的去除率逐渐降低。(4)硝基苯的降解途径是：硝基苯→亚硝基苯→苯基羟胺→苯胺。NZVI直接还原硝基苯以及Fe2+辅助还原硝基苯是该体系主要的反应机理。更多还原

【Abstract】 Due to its tiny size, its large surface area and high surface reactivity, NZVI has been considered as a promising environmental remediation technology. However, NZVI is prone to agglomerate and easily oxidized by oxygen when exposed to air, leading to restrict its application. Therefore, the study on the enhancement of the stability of NZVI and its high surface reactivity has become the hot topics in related researches.In this present study, we chose SBA-15 as a support material to produce stable NZVI dispersions. Moreover, due to its high adsorption capacity SBA-15 can increase the degradation efficiency of pollutants dramatically. The NZVI/SBA-15 composite was synthesized by incipient wetness impregnation, calcinations and reduction, which exhibited the synergetic effect of high adsorption capacity of SBA-15 and high reducibility of NZVI. The NZVI/SBA-15 composite was characterized by X-ray diffraction(XRD), transmission electron microscopy(TEM), and N2 adsorption/desorption. Furthermore, the adsorption and degradation process of nitrobenzene on NZVI/SBA-15 composite was investigated, and the effect factors of nitrobenzene removal were discussed. The pathway of NZVI reducing nitrobenzene and the reduction mechanism of nitrobenzene was also researched. The results showed that:(1) with increasing the percentage of iron species in NZVI/SBA-15 composite, the orderity、the BET surface area and the total pore volume decreased, but still maintained the structure of SBA-15.α-Fe0 nanoparticles were well dispersed in the channels of SBA-15. However, agglomeration of iron particals unsupported took place, leading to increase its partical size.(2) The removal rate of nitrobenzene from aqueous solution on SBA-15, NZVI and NZVI/SBA-15 composite was 51.59%.56.01% and 94.94% respectively after 12h of reaction. The nitrobenzene removal rate by the NZVI/SBA-15 composite was enhanced apparently owing to the synergetic effect of high adsorption capacity of SBA-15 and high reducibility of NZVI.(3) The removal rate of nitrobenzene increased as the percentage of iron species in NZVI/SBA-15 composite and dosage increased. The acidic condition was conducive to enhancement of reaction rate, but the alkaline condition prevented the reaction rate. The removal rate of nitrobenzene decreased as the initial concentration of nitrobenzene increased.(4) The pathway of nitrobenzene reduction by NZVI was described as:nitrobenzene→nitrosobenzene→phenylhyoxylamine→aniline. It was the Fe2+ associated with the iron in the NZVI/SBA-15 composite that was mainly responsible for nitrobenzene reduction.更多还原