| 英文摘要 |
For varying wastewater quality and the need of environmental protection, in-situ analysis of chemical oxygen demand (COD) has become more and more important. Also, although the in-situ analysis of metal ions have been developed for decades, there are still many problems. Thus, one objective of this project is to continue the study of previous year and to review related literatures and techniques. For the in-situ analysis of metal ions, there are techniques based on colorimetry, ionic exchange electrodes, UV-Vis spectrophotometry, and anodic stripping voltammetry. Though ionic exchange electrode have been used widely for in-situ monitoring of metal ions, the speciation of metal ions cannot be obtained and there is no electrode for several metal ions, such as mercury and arsenic. The anodic stripping voltammetry has found to be a promising technique for many rare elements. The main goal of this project is to develop a SWCNTs/ TiO2 composite modified electrode for the analysis of COD via linear scanning voltammetry (LSV). Defunctionalization has been conducted via heat treatment and neutralization by alkaline solution. The surface physical and chemical properties of SWCNTs/TiO2 composite treated by various conditions have been investigated. It is determined that the heat treatment at 300℃is the most suitable defunctionlization condition. The scan rates and pH values of modeled and real wastewater have been determined. Maybe because the compounds which have contribution to COD are small, therefore, it is found that the scan rate has no significant influence for the oxidation peak potential. It is also found that the correlation between oxidation peak current and COD concentration changes as the COD concentration increases. Analysis of KHP solution by defunctionalized SWCNT/TiO2 modified GCE electrode has shown that the stability and the sensitivity LSV method are improved. The defunctionlized SWCNT/ TiO2 modified GCE electrode is then further used to examine the response of peak current to the wastewater. It is found that the peak current are in good relationship with the COD obtained by standard method when the wastewater is treated (or about to discharge). However, LSV method may not be suitable for raw wastewater before any treatment due to the complicated composition and the size of the organic pollutants.
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