【作者】 艾仕云；

【导师】 金利通；

【作者基本信息】 华东师范大学 ， 分析化学， 2004， 博士

【摘要】 随着环境污染的日益严重，环保部门对环境的监测力度不断加大。其中监测设备的高科技化是现代化监测的标志。水质的污染是环境污染的一大方面，污水能否达标排放由污水的污染指数决定，其中最重要的指标是污水的COD值。COD是指在一定条件下，水体中有机物或其它还原性物质被强氧化剂氧化所消耗的氧化剂所对应的氧的物质浓度，以氧的mg1^-1来表示。测定过程中有机物或其它还原性物质的氧化程度决定了测定COD结果的准确程度。纳米半导体氧化物具有特异光电特性，其在电或光激发下，能产生具有强氧化性的含氧自由基（如羟基自由基（HO·））等一类强氧化剂，可将水中污染物完全电催化或光催化降解为水和二氧化碳。利用此原理可望实现有机污染物的快速氧化，通过安培法或光度法来确定水体中有机物的含量。从而实现对有机污染物的快速、实时监测，为环境污染物的监测提供一种全新的理念和思路。 本论文分为三个层次，首先在制备了多种纳米半导体氧化物的基础上，探讨了提高纳米半导体氧化物电催化或光催化活性的性能和提高其催化氧化有机物的最佳途径；然后利用毛细管电泳-安培检测（CZE-AD）技术和自旋捕捉-电子自旋共振（ESR）等方法，检测了纳米半导体催化氧化体系中，活性物种羟基自由基（HO·）的存在，为羟基自由基的检测和揭示纳米半导体氧化物的氧化机理提供了有用的分析检测手段；最后探讨了利用纳米半导体氧化物作为电催化或光催化催化剂用于COD监测，研究了测定COD的原理，并在此基础上开发和研制了“快速在线COD电化学监测仪”和“COD快速光分析仪”等监测仪器。这些工作的开展将纳米科学与分析化学有机的结合起来，为深入研究纳米材料的催化氧化机理和其在分析化学中的应用提供了理论根据，对纳米技术、分析化学、环境化学、环境监测以及分析仪器的开发都具有重要的意义。 （1） 综述部分 该部分从纳米材料的发展、纳米半导体氧化物的制备和在环境分析中的应用的研究及进展、纳米半导体催化氧化原理及含氧自由基的测定的研究和进展以及废水体系中COD快速监测仪开发的现状四个方面进行阐述，对当前本领域的现状与进展做了较为详纳米半导体氧化物的制备及其在化学需氧量检测中应用的研究细的概括和综述。（2）纳米PbO:修饰电极的制备及表征 作为一种阳极材料，PbO:导电性好、氧过电位高，且对氧化剂和强酸惰性好，对阳极氧转化反应有很高的电催化活性，因而近年来引起了人们极大的关注。PbO:修饰电极可通过电沉积的方法从含低价态的Pb2+溶液中制得，它的电催化活性主要取决于沉积Pbo:修饰膜的结构、表面形貌和相态，而这些与沉积条件有极大的关系。本部分利用Pt旋转圆盘电极研究了PbO:修饰电极的制备条件和PbO:修饰膜的形成机理。详细讨论了F’、Ce（川）以及其它过渡金属阳离子掺杂剂对PbO:修饰膜的影响。利用循环伏安、XRD、SEM、AFM和STM等手段考察了修饰电极的表面形貌和组成。通过对不同掺杂剂的选择，成功地制备了纳米PbO:修饰电极。（3）纳米Pbo:修饰电极电催化氧化性能的研究 一般地，好的电催化阳极材料应满足两个条件，一是有高的过电位，二是在电极表面有多的催化活性位点，能提高电极表面水分解生成HO.的速率。本部分利用旋转圆盘电极对纳米PbO:修饰电极的电催化氧化性能进行了初步的研究。实验表明由于电极表面PbO:晶粒呈纳米结构，使纳米PbO:修饰电极表面具有大的比表面积，高的表面活性中心，良好的导电性及宏观隧道效应，使得纳米PbO:修饰电极对有机物有很好的催化氧化性能，用安培法测定了多种有机物在纳米PbO:修饰电极上的电流响应。实验表明，纳米PbO:修饰电极可以作为电化学传感器用于有机化合物的测定。 （4）纳米PbOZ修饰电极电催化氧化机理的研究 近年来，金属氧化物阳极材料在电合成、污水处理等领域得到了很大的发展，但对其表面的氧转化反应机理的认识研究还很不足。本部分用循环伏安和毛细管电泳一安培检测技术（CZE一AO）研究了纳米PbOZ修饰电极表面氧转换反应中轻基自由基（·OH）的产生及其与水杨酸反应的机理。实验表明，在纳米Pbo:电极上HZO于1 .ov一1 .4v分解形成·OH，而Pt电极此现象不明显。探索了用CZE一AD间接测定·OH的优化条件，实验发现，当用水杨酸捕获纳米PbOZ修饰电极表面产生的·OH时，形成的轻基化产物2，5一二轻基苯甲酸（2，5一DHBA）多于2，3一二轻基苯甲酸（2，3一DHBA），这可能是由于在捕获·OH前水杨酸首先在纳米PbO:修饰电极表面形成了活性芳香环自由基，·OH优先进攻芳香环的5一位的结果。 （5）纳米PbO:传感器测定c0D的研究 COO被普遍用作衡量废水中有机物污染程度的一个参数。常用的COD测定方法有华东师范大学申请博士学位论文纳米半导体城化物的制备及其在化学需氧量检测中应用的研究高锰酸盐指数法和重铬酸钾氧化法。这些方法耗时长，操作过程繁琐，且需使用昂贵（AgZSO;）或有毒（Hgs04）的试剂。近年来，电化学法测定COO值得到了发展和关注。本部分研究了以纳米PbO:修饰电极为电化学传感器测定化学需氧量（COD）更多还原

【Abstract】 With the increasingly severe environmental pollution, the department of environmental protection is attaching greater importance on the environmental detection. The advance of the detective equipment is the indication of the modern detection. The water pollution is a large aspect of the environmental pollution. Whether the sewage can reach the emission standard is determined by the contaminative index of the sewage, among which the most important is the COD value of the sewage. COD is defined as the amount of oxygen equivalents consumed in the oxidation of organic compounds by strong oxidizing agents such as dichromate or permanganate and is expressed by quantity (mg l-1) of oxygen. The accuracy is determined by the oxidizing extent of the organic compounds or other reductive substances. With its special photoelectrical characteristic, nano-semiconductor oxide can produce strong oxidizing agents which include oxygenic radicals such as HO-, through which the pollutant in the aqueous system will experience electrocatalytic or photocatalytic process and then be reduced into water and carbon dioxide. On the basis of this theory, the fast oxidation of the organic pollutants and the measure of the quantity of the organic compounds in the aqueous system through amperometry or photometry can be achieved, which will bring about the fast and on-line detection of the organic pollutants and provide a brand new concept and method.This dissertation fell into three hierarchical levels and ten sections. Firstly, on the basis of the preparation of many kinds of nano-semiconductor oxides, how to improve the electrocatalytic or photocatalytic property of the nano-semiconductor oxides and how to optimize the best path of the oxidation of the organic compounds were discussed. Then the existence of HO-, the active substance, was detected in the catalyticai and oxidizing system of the nano-semiconductor by CZE-AD, ESR, etc, which provided a useful analytical and detective method for the detection ofthe HO- and display the oxidizing mechanism of the nano-semiconductor. Lastly, the optimal technological conditions of the detection of the COD by making use of nano- semiconductor as the catalyst in the electrocatalytic or photocatalytic reaction was discussed and its basic theory, on which some detective equipments such as "fast on-line COD electrochemical detector" and "fast COD photoanalytic instrument" were developed. These works combined the nano-science with analytical chemistry and provided an effective method for further researching the oxidizing and catalytic mechanism of the nanomaterials, their application in the analytical chemistry and the development of the products, which had a deep meaning in the nanotechnology, analytical chemistry, environmental chemistry, environmental detection and the development of the analytical instruments.(1) Critical ReviewsIn this part, four parts, that is, the development of the nanomaterial, the preparation of the nano-semiconductor oxides and their application and development in the environmental analysis, the oxidizing and catalytic mechanism of the nano-semiconductor and the research on the measurement of the oxygen containing radicals and the current circumstances of the development of the fast COD detector in the waste water system were discussed and a detail outline and review of the development in the current area was introduced.(2) Preparation and characterization of nano-PbOz modified electrodeOf late, there is a great interest in the improvement of lead dioxide as an anode material owing to its high electrical conductivity, large oxygen overpotential and chemical inertness. PbO2 can be obtained as anodic deposits from solutions of the low-valence ions. Its electrocatalytic activity depends upon its structure, morphology and phase composition, which are highly relied on deposition methods. In this chapter, a lead dioxide film modified electrode was prepared at platinum substrate and its deposition conditions and formation mechanism were studied. The effect of F", Ce3更多还原