流动注射-电化学氧化法测定水体化学需氧量

Flow injection analysis of COD based on electrochemical oxidation method

采用硼掺杂金刚石(Boron-doped diamond,BDD)薄膜电极为工作电极,利用流动注射分析方法测定水体化学需氧量(COD),根据水样中有机物组分在工作电极表面氧化消耗的电量(Qoxidation)测定样品的COD值。考察了一些基本参数包括载液、工作电位、流速对检测信号的影响并选定了最佳检测条件。在最佳检测条件下,本法检测COD的线性范围为2.5~120 mg/L,检出限为1 mg/L。用该法测定化工厂和食品厂废水的COD值,相对标准偏差和回收率分别在2.4%~4.8%和96%~106%之间,且检测结果与国家标准方法(CODcr法)有良好的一致性。

A flow injection analysis(FIA) method for the determination of chemical oxygen demand(COD) based on boron-doped diamond(BDD) film electrode has been described.In this method,the electric quantity consumed by the electrochemical oxidation of the organic species existing in the water samples was defined as the measurement signal.The influence of several basic experimental parameters including supporting electrolyte,applied potential and flow rate on the response of the BDD electrode was investigated and the optimal operating conditions were obtained.Under optimal conditions,a linear range of 2.5～120 mg/L and a detection limit of 1 mg/L were obtained.The method has been applied to the determination of the COD of the waste water samples from chemical manufactory and food industry,the relative standard deviations(RSD) and recoveries were 2.4%～4.8% and 96%～106%,respectively.Additionally,the COD values of the real samples determined by the proposed method agreed well with those by the national standard dichromate method.