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本文研究了一种测定水样中化学耗氧量(COD)的新方法——双中间体库仑法(以下简称(DIC法)。方法基于在1.2M HNO_3和1.5M H_2SO_4混合介质中。电生CeⅣ作氧化剂以消化水样样品,过量的CeⅣ以电生FeⅡ反滴,根据所消耗的电生CeⅣ的时间而算出COD值。并将该法与高锰酸钾标准方法进行了比较。文中还对电生CⅣ和FeⅡ的电流效率以及影响电流效率的因素进行了讨论;也对某些纯有机化合物的COD值及氯离子对测定COD的影响进行了研究。DIC法操作简便、快速、重现性好,便于仪器化,可用于测定天然水及任何污水样品的COD。
A new method for the determination of chemical oxygen demand (COD) in water samples, the double intermediate coulometric method (DIC method), was studied in this paper.The method was based on the mixed media of 1.2 M HNO 3 and 1.5 M H 2 SO 4. Ce Ⅳ was used as oxidant to digest water sample, excess Ce Ⅳ was titrated electronically by FeⅡ, COD was calculated according to consumed time of electrogenic Ce Ⅳ, and the method was compared with the standard method of potassium permanganate. The current efficiency of C IV and FeⅡ and the factors that affect the current efficiency are discussed, and the COD value of some pure organic compounds and the effect of chloride ion on the determination of COD are also studied.The DIC method is simple, rapid and reproducible Good, easy to instrument, can be used to determine natural water and any sewage samples COD.