【作者】 喻德忠；

【导师】 蔡汝秀；

【作者基本信息】 武汉大学 ， 分析化学， 2004， 博士

【摘要】 纳米科学技术是上世纪八十年代末诞生并正在蓬勃发展的一种高新科技,它的内容是在纳米尺寸范围内认识和改造自然,通过直接操纵和安排原子分子而创造新物质。纳米材料是纳米科技的基础,被誉为21世纪最有前途的材料。纳米材料一般是指尺寸在1nm到100nm之间的粒子,是处在原子簇和宏观物体交界的过渡区域。纳米材料分为两个层次,即纳米超微粒子与纳米固体材料,纳米超微粒子指的是粒子尺寸为1～100nm的超微粒子;纳米固体是指由纳米超微粒子制成的固体材料。由于纳米粒子本身的结构和特性决定了纳米固体材料的许多新特性。它所具有的体积效应、表面效应、量子尺寸效应和宏观量子隧道效应使得纳米材料在固体力学、电学、磁学、光学和化学活性等方面具有奇特的性能,因而在许多方面有着广阔的应用前景。 环境污染是全世界所关注的问题,能否有效地治理环境污染,对于保护环境、维持生态平衡、实现可持续发展具有重大意义。半导体纳米材料由于具有独特的光化学反应活性、双电层羟基配位吸附特性以及高比表面积,已引起了人们的广泛兴趣。近年来,具有半导体特性的金属氧化物纳米粒子,如纳米二氧化钛、纳米硫化镉等,在光降解处理环境污染物中得到了广泛的应用.但这类处理方法常需要光催化活性很高的纳米’TiO₂和人工光源,光量子效率低;光催化剂不易固定;反应酸度较高,需在通入O₂或N₂的条件下进行且要求被处理体系具有良好的透光性,在实际应用中受到了限制。因此,如何利用纳米材料的独特性质,在较简单的工艺条件下,有效地处理环境污染物,一直是一个具有挑战性和开拓性的课题。 染料污染处理是目前国内外学者所面临的难点问题之一,染料污染主要有偶氮类染料污染、罗丹明染料污染等。近年来,纳米二氧化钛由于其独特的性质,在光催化降解处理染料污染中得到了广泛的应用,但研究对象多为偶氮类染料,对罗丹明染料的处理及光解机理研究,有关报道则较少。 环境分析是环境污染物治理的眼睛,有着举足轻重的作用,但在实际工作中,环境样品的成分经常非常复杂,由于基体干扰及分析方法灵敏度等原因,往往不能更多还原

【Abstract】 Nanometer science & technology has been rapidly developing ever since 1980’s, which means recognizing and reconstructing the nature on the level of nanometer size, and also creating new substances through directly driving atoms and molecules. Nanometer sized materials, as the basis of nanometer science & technology, are considered as the most promising materials in the 21^th century. Generally speaking, nanometer sized materials refer to those particles sized between 1-100 nm, which falls into the interface area of atom clusters and macroscopical substances. Nanometer sized material is classified into two levels: nanometer particles and nanometer sized solid materials, the former refers to ultra-micro particles sized in l-100nm, and the later is just the solid material made from such particles. The special structure of nanometer particles has resulted in many unique properties of nanometer sized solid materials. That is to say, the volume effect, surface effect, quantum effect and macroscopical tunnel effect have lead to its special characteristics in mechanics, electrics, magnetics, optics and chemical activity, and thus decided the wide application foreground in many fields.Environment pollution is an issue attracted the scientists all over the world. Whether environment pollution can be controlled effectively or not is very significant in protecting environment, maintaining zoology balance and achieving sustained development. Nanometer-sized semiconductor materials are characterized with photochemical reaction activity, double electrical layers hydroxide conjugate adsorption and higher specific surface area, which have attracted many researchers. In recent years, metal oxides semiconductors, such as nanometer-sized TiO₂ and CdS, have been applied widely in photo-degradating the environmental pollutants. However, this kind of methods based on nanometer-sized TiO₂ which has high photo- catalyzing activity is always faced with some problems, i.e., a manual light source is needed, photons efficiency is rather poor, immobilization of the photo catalyzer is difficult, strong acid reaction medium is needed, additional introduction of O₂ or N₂ into the system is necessary and the taken system must be light-pervious. Hence the application of the methods is limited. Therefore, to deal with the environmental pollutants with using nanometer-sized materials under relatively simple technical conditions has all the times been a challenging and innovative subject.Dealing with the dye pollution is one of the difficult matters that confront scholars all over the world. Dye pollution mainly comes from the azo dyes and rhodamine dyes.During recent years, nano-TiO2 has been applied widely in photodegradation of the environmental pollutions due to its specific characteres, whereas the studied objects are usually the azo dyes and reports on the treatment and degradation mechanism of rhodamine dyes are relatively less seen.Environmental analysis is the eye of environmental pollutants control, which is very important. However, in the practical work, the environmental samples are very complex and difficult to analyze because of the background interference and restriction of sensitivity of analysis methods. Solid-phase micro-extraction is an effective technique for separating and concentrating. The property of the adsorption materials used is a crucial factor affecting the analytical sensitivity and the selectivity. Thus, to find the new excellent adsorption materials is a significant job.The elemental chemical speciation points at the actual forms of elements and compounds existmg in certain ionic or molecular formation. Various form of an element will present quite different environmental behaviors and biological toxicity as well as different availability. So, it is much more significant to study the form of trace element than to analyze its concentration. Obviously, it is highly depended on new methods of form analysis.It is always demanded a quite high sensitivity and selectivity in form analysis, what is more, the formation of the object should be kept unchanged during the sampling and analyzing procedure. Therefore, form analysis is usually more difficult than quantitative determination of an element or a compound, and it is always connected with separation and concentrating operations.Nowadays, various of separation techniques have been applied in form analysis, which include HPLC, IC, SFC, GC, CZE, and so on. However, these separation techniques always need particular instruments with high cost.Adsorption materials have also been applied in form analysis today. On basis of the difference in adsorbing ability of the materials between different forms, some formation is concentrated or eliminated so as to facilitate the subsequent determination.In this thesis, the work is focused on the application of nanometer sized metal oxides in the fields described above, which mainly includes the following aspects.1. Three kinds of nanometer metal oxide powder were synthesized with Sol-Gel method. The diameter of powder was controlled with surfactants. The average diameter and specific surface area were measured. The synthesis condition, average diameter, specific surface area, stability and photo-catalyzing activity of the three oxides werecompared systematically.2. The photo-chemical reactivity of nanometer ZnO was applied in photo-degradation of Rhodamine dye. Dynamic molecular spectroscopy was used to trace the kinetics and mechanism of dye on the surface of ZnO. The applicability of nanometer sized ZnO in photo-degradation of rhodamine dye is studied.3. Adsorption behaviors of several metal ions, to say, V（V）,Cr（VI）,Mo（VI） and W（VI） on nanometer ZrO2 and Fe2O3 were studied systematically. Factors affecting the adsorption and diluting of these ions were examined. Special emphasis was put on the study of Cr（VI）, a kind of highly toxic pollutant, thus a new method for treating Cr（VI） ion was built up based on the adsorption power ofZrOi and Fe2O3.4. Adsorption behaviors of V（V） on nanometer ZrO2 was studied and a separation and pre-concentration method for trace amount of V（V） in environmental samples was proposed. The sensitivity and selectivity of the method was much higher than existing methods.5. Adsorption behaviors of three kinds of azo dyes on nanometer ZrO2 were studied. Experimental conditions were optimized and the possibility of eliminating pollution of dyes with nanometer ZrO2 was discussed.6. Adsorption behaviors of As（III）/As（V） on Z1O2 as well as affecting factors including the diluting conditions were studied with spectrophotometry, hence the application of ZrO2 in form analysis was looked in.7. Based upon the above work, the adsorption mechanism of these nanometer sized metal oxides was discussed preliminarily. And the possibility of reusing these metal oxides was studied.更多还原