测定水样化学需氧量的方法比较

Comparison of Methods for Determining Chemical Oxygen Demand

利用2种浓度不同的重铬酸钾消解测定化学需氧量(COD),并通过标准样品和实际样品对不同方法的准确度进行了验证。当COD浓度在50~250 mg/L之间且氯离子浓度<2000mg/L时,可以采取减少取样体积的方式用低浓度重铬酸钾消解,此方法适合测定浑浊度小的水样;当COD浓度在100~250 mg/L之间且氯离子含量<1000mg/L时,可以选择低浓度或高浓度重铬酸钾进行消解法;当COD浓度>250 mg/L且氯离子浓度<1000mg/L时,应选择高浓度重铬酸钾进行消解。

The chemical oxygen demand(COD)was determined by digestion with two different concentrations of potas-sium dichromate,and the accuracy of the different methods was verified by standard samples and actual samples.When the COD concentration is between 50 mg/L and 250mg/L and the chloride ion concentration is less than 2000mg/L,it can be digested with low-concentration potassium dichromate by reducing the sampling volume.This method is suitable for measuring water samples with low turbidity.When the COD concentration is between 100 mg/L and 250mg/L and the chloride ion content is less than 1000 mg/L,low or high concentration of potassium dichromate can be selected for the digestion.When the COD concentration is greater than 250 mg/L and the chloride ion content is less than 1000mg/L,a high concentration of potassium dichromate should be selected for digestion.