还原性物质对化学需氧量(COD)测定的影响及消除方法

On the Effect of Reducible Substances on COD Determination and elimination

文中论述了还原性物质Cl-、NO2-、Fe2+、S2-、NH3、NH4+等离子对化学需氧量测定的影响,着重探讨了消除上述离子的方法及原理,从而得出消除氯离子干扰可用银柱法的结论,特别是高氯离子浓度(>20 000mg/L)的水样,其效果更佳。NO2-的干扰可通过加入氨基磺酸来消除。Fe2+,S2-干扰可通过在水样中通入空气,使之氧化除去来加以消除。NH3或NH4+干扰的消除,可通过除去水中的氯离子或用低浓度的K2Cr2O7溶液测定来加以消除。

The effects of reducible maters for example Cl^-,NO2^-,Fe^2＋,S^2-.NH3,NH^4＋ etc, on measurement of chemical oxygen demand were discussed, the emphases of discussion were focused on degradation methods and principles of mentioned substances, thereby arrived a conclusion that silver column method can be used for interference elimination of chloride ion, in particular this method is fruitful to water sample of heavy-chloride concentration （〉20 000 mg/L）, the method of sulfamie acid accession can be used to the interference elimination of NO2^-, the oxidation process of which air were insufllated into water sample to fulfill oxidation of Fe^2＋, S^2- can be used to interference elimination of Fe^2＋, S^2-. on the other hand the method of eliminating chloride in water sample and that of using low concentration of K2Cr2O7 solution were can be used to he interference elimination of NH3 and NH^4＋.