氧化铒催化微波消解快速测定化学需氧量

RAPID DETERMINATION OF COD_(Cr) OF DOMESTIC SEWAGE——DIGESTION OF SAMPLE BY MICRO-WAVE HEATING CATALYZED WITH ERBIUM OXIDE

建立了一种测定化学需氧量(COD)的新方法。在体积比为4∶1的硫酸和磷酸混酸溶液中,重铬酸钾作氧化剂,氧化铒(Ⅲ)催化微波消解生活污水,过量重铬酸钾用1,10 菲绕啉指示,硫酸亚铁铵标准溶液滴定。对邻苯二甲酸氢钾标准溶液和生活污水进行了测定。测定结果,回收率为99.6%～101.2%,8次平行测定的相对标准偏差为1.9%～2.7%。方法准确、简单、快速。

In the determination of COD_(Cr) of domestic sewage, the sample was digested in a mixed acid (conc. H_2SO_4+conc. H_3PO_4=4+1) by heating in a micro-wave oven. The potassium dichromate standard solution was added as oxidizing agent and erbium oxide (Er_2O_3) added as catalyst. After the digestion was completed, excess of the dichromate in the solution was back-titrated with standard ferrous ammonium sulfate solution using (1,10-phenanthroline) as indicator. By this new method, the time of digestion was shortened from 2h to only 7min. The proposed method has been applied to the analysis of standard potassium biphthalate and domestic sewage samples, giving RSD′s (n=8) in the range from 1.9% to 2.7%. Recoveries in the range of 99.6%～101.2% were obtained.