| 摘要: | 化學需氧量(chemical oxygen demand ,COD)是水質評估的重要分析參數之一。 傳統 COD 標準方法分析時間長、氧化能力有限、且會用到有毒的試劑會對環境 造成二次污染等缺點。而電化學方法不僅具有分析快速、靈敏度高、環境友好等 優點，而且可應用於現場監測分析，具有良好應用前景。 本研究採用溶膠凝膠法製備了 TiO2/ SWCNT(titanium dioxide/single-walled carbon nanotubes)複合材料，並將其應用於玻璃碳電極(glassy carbon electrode, GCE)上。通過線性掃描伏安法(linear sweep voltammetry ,LSV)對模擬水樣和真實 水樣進行 COD 分析。為了評估該修飾電極的有效性，透過在水中混合幾種具有 代表性的有機化合物來製備模擬水樣。這些有機化合物分為三類。第一種是常用 於 COD 分析的標準樣品第二種是工業廢水中常見的污染物及環境中之自然水體 中常見的天然有機物。單一化合物的模擬水樣中獲得的峰值電流與理論需氧量 (theoretical oxygen demand ,ThOD)呈正相關，並且針對常見的 COD 干擾物進行討 論，發現過高濃度的鐵離子以及亞硝酸鹽氮會對電極在測定上造成干擾。最後對 實際水樣進行分析研究，實際水樣分別選用學校內的中大湖、百花川、北區生活 污水及工業區污水進行電化學分析。為了獲得不同的 COD 值將真實水樣稀釋成 不同濃度，部分水體中稀釋後的峰值電流會與 COD 呈負相關，為進一步確認原 因分析了相同基質下的真實水樣，在此操作條下峰值電流則與 COD 呈正相關， ii 這可能是因為水體中的某種物質遮蔽了電極訊號導致水樣稀釋後的峰值電流反 而會上升。 在相同的基質下即使為不同天不同電極測定的水樣，透過 ECSA 計算可以減 少因為電極活性不同所造成的誤差，結果表示用 LSV 建立的擬合方程對較穩定 的水樣進行 COD 的測定是可行的，TiO2/SWCNT/GCE 在三個月中測定不同真實 水樣後，其峰值電流平均為 300μA，RSD 為 6.29%證實 TiO2/SWCNT/GCE 電極 具有良好的長效性。;Chemical oxygen demand (COD) is one of the crucial parameters for water quality assessment. Traditional COD standard methods have disadvantages such as lengthy analysis time, limited oxidation capability, and the use of toxic chemicals leading to secondary pollution. Electrochemical methods offer advantages such as rapid analysis, high sensitivity, and environmental friendliness. Moreover, they can be applied for onsite monitoring, showing promising applications. In this study, a sol-gel method was employed to prepare TiO2/SWCNT composite material, which was applied onto a glassy carbon electrode (GCE). COD analysis of single-compound synthetic water and real water samples was conducted using linear sweep voltammetry (LSV). To evaluate the effectiveness of the modified electrode, simulated water samples were prepared by mixing several representative organic compounds, categorized into three types. The first type comprised standard samples commonly used in COD analysis, the second type included pollutants found in industrial wastewater, and the third type consisted of naturally occurring organic substances in environmental water bodies. The peak currents obtained from single-compound simulated samples were positively correlated with Theoretical oxygen demand (ThOD), and discussion on common COD interferents revealed interference from high concentrations of iron ions and nitrate nitrogen. iv Finally, real water samples from different sources, including Zhongda Lake, Baihua River, North District domestic sewage, and industrial zone wastewater, were analyzed using electrochemical methods. Dilution of real water samples to obtain different COD concentrations showed a negative correlation between peak currents and COD in some water bodies. Further analysis of real water samples with the same matrix under similar conditions demonstrated a positive correlation between peak currents and COD, possibly due to a substance in the water masking the electrode signal, causing an increase in peak currents after dilution. ECSA calculations for samples with the same matrix and different electrodes, even on different days, helped reduce errors arising from varying electrode activity. The results indicated that establishing a fitting equation using LSV for stable water samples is feasible. After three months of analyzing different real water samples, the average peak current for TiO2/SWCNT/GCE was 300 μA with an RSD of 6.29%, confirming the electrode′s excellent long-term stability. |
