| dc.description.abstract | 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. | en_US |