废水中EDTA与总重金属含量的同时测定

在被EDTA和重金属离子污染的废水中，由于它们之间的络合作用，很难用简单的方法测出二者的含量。本文在强酸性和加入助萃络合剂的条件下，使EDTA与重金属离子分离。采用离子缔合萃取法，将水中的重金属离子萃于有机相，用分光光度法可测定出水中EDTA的总浓度。另取一份平行样，加入过量且定量的EDTA标准溶液，同水中未与EDTA络合的重金属离子络合，再进行返滴定。通过萃取与返滴定的巧妙结合，可求出水中重金属离子的总量。本法操作简便、快速，不需大型仪器，特别适合于被EDTA和(或)重金属离子污染的废水测定。

Simple and simultaneous determination of EDTA and general heavy metals in wastewater

In the waste water polluted by EDTA and heavy metals, it is difficult to determination of its content by simple method because of complex formed. A new method is proposed as follows: In the presence of strong acid and aid-extraction complexing agents EDTA can be separated from EDTA-metal complex. The heavy metals are extracted to the organic phase by the ion association extraction and total amount of EDTA is analysed with spectrophotometry. Take a replicate sample and add EDTA standard solution of excess and fixed quantity to the sample, then carry out the back titration. The total content of heavy metals can be calculated by ingenious combination of extraction and back titration. This method is characterized in simpleness and time-saving without expensive instruments and specially adequate to determination of waste water polluted by EDTA and (or ) heavy metals.