纳米零价铁对阳离子染料脱色降解的研究

发布时间：2018-01-03 17:13

本文关键词：纳米零价铁对阳离子染料脱色降解的研究　出处：《昆明理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：染料废水具有较高的稳定性和复杂的芳香结构特点,对染料废水的降解成为了关注热点。由于水体中存在染料,它的颜色直接影响水生生物的光合作用,其有毒性的致癌性则会影响水生生态系统和食物链,还会威胁到人类的健康。对于染料的降解,国内外研究者采用了不同方法,使难降解的有机物化学结构改变,提高了废水的生化性,对其毒性进行了消除或降低,以便使难以降解的有机物在后续的生化处理中得到彻底降解。近年来,纳米零价铁颗粒(nZVI)的高表面积体积比提供更多的活性位点,能有效地降解很多污染物等特点引起了广泛的重视。本文以阳离子染料亚甲基蓝和孔雀绿作为研究对象,利用改性后的纳米零价铁颗粒和通过绿茶提取物合成的纳米零价铁颗粒,对两种阳离子染料进行脱色降解反应,具体研究内容和结果如下：1.利用纳米零价铁去除水中各类污染物是近年来的研究热点,但纳米零价铁颗粒在水中的团聚会导致反应活性降低,本研究通过在纳米铁颗粒制备过程中添加分散剂聚丙烯酸(PAA),提高纳米零价铁的分散性,强化其在水中反应活性,通过聚丙烯酸改性合成纳米零价铁颗粒(PAA-Fe),并首次用于降解水中亚甲基蓝。对其进行扫描电镜(SEM)、透射电镜OEM)、X射线衍射(XRD)和比表面积表征分析,分析结果表明,与未改性原始纳米零价铁颗粒相比,PAA-Fe颗粒表面较光滑,团聚减少、颗粒粒径减小,比表面积增大。2.改性剂PAA添加浓度为0.1%时,经过60min降解反应,PAA改性纳米铁颗粒对亚甲基蓝的脱色率为98.84%,较未改性颗粒脱色率提高了27.32%。改性纳米铁颗粒对亚甲基蓝的脱色效果受初始溶液的pH值、初始溶液的浓度、PAA-Fe投加量和反应温度影响。PAA-Fe与亚甲基蓝的脱色反应符合假一级反应动力学规律,活化能为26.53 kJ/mol。3.在室温下以绿茶提取物作为还原剂制备纳米零价铁(G-Fe NPs),用于对孔雀绿进行脱色。因为绿茶提取物包含了丰富的咖啡因／多酚类,在合成纳米铁时即作为还原剂又作为覆盖剂。通过扫描电镜(SEM)和透射电镜(TEM), G-Fe NPs颗粒与硼氢化物合成的纳米铁颗粒(K-Fe NPs)对比,G-Fe NPs颗粒的团聚现象减少,并且反应活性有所增加。红外光谱(FTIR)分析可知G-Fe NPs表面有多酚化合物的基团键,说明了绿茶提取物可当作覆盖剂／稳定剂。4.经过60min降解反应,G-Fe颗粒对孔雀绿的脱色率为90.70%,相较K-Fe颗粒脱色率提高了27.44%。分别考察了G-Fe颗粒对孔雀绿的反应受溶液的pH、孔雀绿的初始浓度、G-Fe颗粒的投加量、反应温度的影响。实验结果表明,G-Fe NPs投加量和温度的增加,脱色率随着增大,而脱色率却随孔雀绿的初始浓度和pH的增大而降低。动力学研究说明G-Fe NPs对孔雀绿的脱色反应呈一级指数衰减趋势。
[Abstract]:Dye wastewater has high stability and complex aromatic structure characteristics, the degradation of dye wastewater has become a hot spot. Because of the existence of dyes in water, its color directly affects the photosynthesis of aquatic organisms. Its toxic carcinogenicity will affect aquatic ecosystem and food chain and threaten human health. Researchers at home and abroad have adopted different methods for the degradation of dyes. The chemical structure of refractory organic compounds is changed, the biochemistry of wastewater is improved, and its toxicity is eliminated or reduced, so that the refractory organic compounds can be completely degraded in the subsequent biochemical treatment. Nanocrystalline zero-valent iron particles (nZVI) have higher surface area volume than provide more active sites. In this paper, the cationic dye methylene blue and malachite green were used as the research objects. Two kinds of cationic dyes were decolorized and degraded by the modified nano-zero-valent iron particles and the nano-zero-valent iron particles synthesized by green tea extract. The specific research contents and results are as follows: 1. The removal of various pollutants in water by using nano-zero-valent iron is a hot topic in recent years, but the agglomeration of nano-zero-valent iron particles in water leads to the decrease of reaction activity. In this study, the dispersing agent polyacrylate PAA was added in the preparation of nano-iron particles to improve the dispersion of nano-zero-valent iron and enhance its reactivity in water. Nano-sized zero-valent iron particles (PAA-FeO) were synthesized by modification of polyacrylic acid and used for degradation of methylene blue in water for the first time. The results of X-ray diffraction (XRD) and specific surface area analysis showed that the surface surface of PAA-Fe particles was smooth, the agglomeration was less and the particle size was smaller than that of unmodified nano-zero-valent iron particles. When the concentration of modifier PAA was 0.1, the decolorization rate of methylene blue was 98.84% after 60min degradation reaction. The decolorization rate of the modified nanoparticles was 27.32 higher than that of the unmodified particles. The decolorization effect of the modified nano-iron particles on methylene blue was affected by the pH value of the initial solution and the initial concentration of the solution. The decolorization reaction between methylene blue and PAA-Fe was in accordance with the pseudo-first-order reaction kinetics. The activation energy is 26.53 kJ / mol 路3.The nanometer zero-valent iron (G-Fe NPs) was prepared by using green tea extract as reducing agent at room temperature. Used to decolorize malachite green because the green tea extract contains abundant caffeine / polyphenols. Nanocrystalline iron is used both as a reducer and as a covering agent by means of scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The agglomeration of G-Fe NPs particles was decreased compared with that of nano-iron particles synthesized by borohydride. The agglomeration of G-Fe NPs particles was decreased compared with that of G-Fe NPs particles. FTIR analysis showed that there were group bonds of polyphenols on the surface of G-Fe NPs. The results showed that green tea extract could be used as covering agent / stabilizer. The decolorization rate of G-Fe particles on malachite green was 90.70% after 60 min degradation. Compared with K-Fe particles, the decolorization rate of G-Fe particles was increased by 27.44%. The pH of solution and the dosage of G-Fe particles were investigated respectively in the reaction of G-Fe particles to malachite green. The experimental results show that the decolorization rate increases with the increase of the dosage and temperature of G-Fe NPs. However, the decolorization rate decreased with the increase of initial concentration and pH of malachite green. Kinetic study showed that the decolorization of malachite green by G-Fe NPs showed a first-order exponential decolorization trend.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X788

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