| Abstract: | 化學需氧量（COD）為環境水體有機污染物含量及水質監測的重要指標之一。傳統COD分析方法仍存在許多缺點，例如：分析時間長、氧化能力受限、高毒性試劑的二次污染等。而電化學方法不僅具有快速分析、高靈敏度、環境友善等優點，還可應用於現場監測及分析，使其逐漸受到關注。
本研究透過溶膠-凝膠法製備二氧化鈦/單壁奈米碳管複合材料並用於修飾電極，以線性掃描伏安法（LSV）在最佳掃描條件（電解質為0.1 M氯化鈉緩衝溶液、掃描速度為0.1 V s–1）下進行水樣之COD分析，包括模擬水樣及真實水樣。其中，模擬水樣分為單一水樣及多成分水樣，單一水樣由鄰苯二甲酸氫鉀、葡萄糖、水楊酸、對-硝基苯酚、甘胺酸、菸鹼酸、四甲基氫氧化銨等有機物配製。多成分水樣則以鄰苯二甲酸氫鉀、水楊酸、對-硝基苯酚三個有機物組合作為分析代表，在不同理論需氧量比例的情況下，探討有機物在電極上的競爭和協同作用。結果顯示，兩種水樣分析所得的峰值電流與理論需氧量皆呈現正相關。真實水樣的分析中，將修飾電極用於測定平鎮工業區污水廠之進流水及放流水，發現LSV與COD標準方法具有相似的趨勢，LSV所建立的擬合方程對於工業廢水的COD量測是可行的。對於修飾電極的再現性及穩定性分析，相對標準偏差分別為4.87%及6.34%。證實了修飾電極在快速量測COD方面具有良好的潛力。
;Chemical oxygen demand (COD) is one of the important indicators to understand the pollution by organic compounds and is usually monitored. The traditional COD analysis methods have disadvantages, such as long-term analysis time, limited oxidation capacity, and secondary pollution of highly toxic reagents. The electrochemical method not only has the advantages of rapid analysis, high sensitivity and environmental friendliness, but also can be applied to on-site monitoring and analysis, so that it has broad prospect.
In this study, the TiO2/single-walled carbon nanotubes (SWCNT) composite was prepared by sol-gel method and used to modify glassy carbon electrode (GCE). The COD analysis of synthetic water and real water was performed by linear sweep voltammetry (LSV) under the optimal scanning conditions (the electrolyte was 0.1 M NaCl and the scanning rate is 0.1 V s–1). The synthetic water were divided into single-compound and multi-compounds systems. The single-compound synthetic water were made of potassium hydrogen phthalate (KHP), glucose, salicylic acid (SA), 4 nitrophenol (4-NP), glycine, nicotinic acid (NA), and tetramethylammonium hydroxide (TMAH). For the multi-compounds synthetic water, KHP, SA, and 4-NP were selected, and the competition and synergetic effects between organic compounds on electrodes were discussed. The results show that peak current obtained from both single-compound and multi-compounds synthetic water were positively correlated with ThOD. For real water samples, the prepared TiO2/SWCNT/GCE was used to determine COD in the influent and effluent obtained from the wastewater treatment plant of Pingzhen Industrial Park. It was found that the LSV and COD standard methods have similar tendency, and the fitting equation established by LSV was feasible for COD measurement of industrial wastewater. For the reproducibility and long-term stability analysis of the TiO2/SWCNT/GCE, the RSD were 4.87% and 6.34%, respectively. Therefore, it is confirmed that the TiO2/SWCNT/GCE has great potential in rapid determination of COD. |
