摘要：

采用重铬酸钾法测定废水中的COD_Cr，其中的氯离子也会被重铬酸钾氧化，从而使测定结果产生正误差，氯离子含量越高误差越大。在现有标准分析方法（重铬酸钾法）的基础上进行改进，通过增加掩蔽剂的方式掩蔽高浓度的氯离子，采用快速密闭消解法测定高氯废水中的COD_Cr。采用改进方法测定COD_Cr标样（含氯离子质量分数8%），RSD分别为6.58%（n=10）、5.47%（n=8）和5.02%（n=8）；采用改进方法测定废水样品（含氯离子质量分数7.76%）和加标样，平均加标回收率为93.9%。经验证，改进方法对于高氯低有机物废水中COD_Cr的测定具有良好的精密度和准确度，据此建立了氯离子质量分数不高于8%的高氯低COD_Cr废水COD_Cr的标准测定方法，方法COD_Cr检出限为6.3 mg/L，定量下限25 mg/L。该研究为高氯低COD_Cr废水无害化处理提供了快速可靠的COD_Cr测定方法。

关键词: COD_Cr, 高氯低有机物废水, 重铬酸钾法, 快速密闭消解法

Abstract:

There were positive errors because of chloride ions being also oxidized by potassium dichromate while potassium dichromate method was used to determine the COD_Cr of wastewater, and the errors were greater while the chloride ions content was higher. The existing standard analytical method(potassium dichromate method) was improved. The high concentration of chloride ion was masked by adding masking agent, and the COD_Cr of wastewater containing high chloride was determined by fast closed digestion method. The improved method was used to determine COD_Cr standard sample(containing 8% chloride), and RSD were 6.58%(n=10), 5.47%(n=8) and 5.02%(n=8). The improved method was used to determine the wastewater samples(containing 7.76% chlorine) and the added standard samples, the average addition recovery rate was 93.9%. It was proved that the improved method had good precision and accuracy in the determination of COD_Cr in high chlorine and low organic matter wastewater. A method for COD_Cr determination of high chlorine wastewater with chloride ion content of no more than 8% was established. The method detection limit was 6.3 mg/L, the quantitative lower limit was 25 mg/L. The problem of COD_Cr determination of high chlorine wastewater was solved, and a fast and reliable COD_Cr determination method was provided for the harmless treatment of wastewater with high chlorine and low COD_Cr.

Key words: COD_Cr, wastewater with high chlorine and low COD, potassium dichromate method, fast closed digestion method

中图分类号: 

• X832