分光光度法测定COD_(Cr)的试验条件选择

Selection of testing conditions of determining COD Cr by spectrophotography

用分光光度法测定水中化学需氧量ＣＯＤＣｒ，通过正交试验选择氧化的最佳选择。试验结果表明对ＣＯＤＣｒ值为５０～１０００ｍｇ／Ｌ的水样：氧化剂Ｋ２Ｃｒ２Ｏ７用量为０．２０～０．４０ｍｏｌ／Ｌ，催化剂Ａｇ２ＳＯ４用量为１０ｇ／ＬＨ２ＳＯ４，消解时间１０ｍｉｎ，加热温度１８０℃。用ＣＯＤＣｒ为１３８ｍｇ／Ｌ的质控标样进行验证试验，其绝对误差为０．５～３．０ｍｇ／Ｌ。与标准方法相比用分光光度法测定ＣＯＤＣｒ具有分析误差小，省时、省力，节约药剂的特点。

Spectrophotography was adopted to determine the COD Cr in water and the optimum condition was chosen by orthogonal test.The testing result indicated that,for water sample with 50～1000 mg/L of COD Cr ,the amount of oxidant K 2Cr 2O 7 was 0.20～0.40 mol/L,the amount of catalyzer Ag 2SO 4 10 g/L H 2SO 4 ,the time of eliminating decomposition 10 min,and the heating temperature 180℃.The absolute errors were 0.5～3.0 mg/L as testing and verifying quality control of standard sample by 138 mg/L of COD Cr .Compared with standard method,spectrophotography was characterized by less analyzing error,time,effort and dose.