高锰酸钾法测定盐酸中化学需氧量

Optimization of COD(The Chemical Oxygen Demand)Test Method in Hydrochloric Acid

在高锰酸钾法测定工业盐酸中化学需氧量(COD)时,通过对盐酸试样先进行中和反应,排除氯离子对测试COD过程的干扰;通过加热沸腾试验,选择最佳时间为30 min,使COD测试数据的更加准确。精密度和准确度试验表明:对样品进行中和处理后再用高锰酸钾法测定COD,操作简单,测定结果的相对平均误差小于5%,平均加标回收率在98.0%~102.0%,能满足检测要求。

When using Potassium permanganate method testing COD value of Hydrochloric acid.Because there are lots of the chloride ion in the sample.GB/T15456-2008 Industrial circulating cooling water—Determination of the chemical oxygen demand—Potassium permanganate method unable to meet the requirements of analytical inspection.By adjusting the pH of the sample from the comparison experiment.Firstly,the neutralization reaction of the hydrochloric acid samples eliminated the interference of chloride ion on COD value.After that,heating digestion making the experiment data more accurate.Precision and accuracy tests indicate that the COD was measured with potassium permanganate after neutralizing the sample and the operation was simple.The relative average error difference between the measured results is less than 5%,and the average calc recovery rate is between 98.0%and 102.0%,which can meet the detection requirements.