| With the increasing 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 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 photoelectric characteristic, metal oxides 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 measurement 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.In this paper, the metal oxides with electrocatalytic or photocatalytic ability were prepared. The electrocatalytic or photocatalytic oxidation of organic compounds was discussed. And the two new COD measurement methods using these oxides were proposed. The measuring principle was based on the signals that were produced in the process of electrocatalytic or photocatalytic oxidation proportional to the quantity of organic compounds. The two new methods were characterized by low detection, wide... |
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