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在线水质监测亟需快速、准确的电化学COD传感器.以电化学沉积法制备的石墨基β-PbO2电极材料为工作电极时,其阳极响应电流强度Iresp与电解液中的有机物COD理论值之间呈良好的线性关系(R2>0.99),这是其作为COD电化学传感器的良好基础.然而,不同种类有机物的COD理论值(CODTh)与Iresp间的线性系数相差达1~2.3倍,该现象将影响真实水样的COD测定准确性.本研究通过电化学反应机理分析,认为扩散控制和电化学矿化反应控制二者之间的差异是造成不同种类有机物Iresp-CODTh线性斜率不同的主要原因.藉此,本研究建议在采用恒电位法测试COD值时,加强搅拌、增加电极表面吸附活性位点数量以及使用混合水样制作标线等方法提高测定准确性.
Electrochemical COD sensor is urgently needed for on-line water quality monitoring.When the graphite-based β-PbO2 electrode material prepared by electrochemical deposition is the working electrode, the relationship between the anode response current Iresp and the theoretical COD of organic compounds in the electrolyte (R2> 0.99), which is a good basis for COD electrochemical sensor.However, the difference between COD theoretical value (CODTh) and linear coefficient between Iresp and different kinds of organic matter is 1 ~ 2.3 times, Will affect the accuracy of COD determination of real water samples.In this study, electrochemical reaction mechanism analysis shows that the difference between diffusion control and electrochemical mineralization control is the main reason for the different linear slopes of Iresp-CODTh Therefore, this study proposed to increase the agitation, increase the number of active sites adsorbed on the electrode surface, and use the mixed water sample to make the markings to improve the determination accuracy when using the constant potential method to test the COD value.