复杂高铋物料中铅的Na2EDTA滴定法测定

复杂高铋物料中，铋、砷、锑、锡四元素含量高且共存时会影响铅的测定。特别是铋含量高时对铅的测定影响大。实验用EDTA—酒石酸联合掩蔽铋、砷、锑、锡，在稀硫酸介质中以硫酸钾为沉淀剂，使铅生成硫酸铅钾复盐沉淀而与铋、砷、锑、锡、铁、铜、锌、铝、钴、镍等干扰离子分离，沉淀以乙酸-乙酸钠浸取，二甲酚橙为指示剂，Na2EDTA滴定法测定铅。试验进一步优化了测定条件，确定最佳条件：硫酸（1 1）加入量为7mL、硫酸钾用量为5g、煮沸时为5min、沉淀陈化时间为2h、EDTA 50g/L 加入量为10mL、酒石酸用量为0.5g，铅的回收率99.70% ～100.65%。将实验方法应用于测定复杂高铋物料中铅，标样BY0111-1与给定值一致，相对标准偏差（n=11）RSD 0.20%～0.23%，满足生产测试要求。

Determination of lead in complex and high bismuth materials by Na2EDTA titration method

The content of bismuth, arsenic, antimony and tin in complex and high bismuth materials can affect the determination of lead. Especially when the content of bismuth is high, the determination of lead is very important. Experiment with EDTA - tartaric acid combined masking, bismuth, arsenic, antimony, tin in dilute sulphuric acid medium with potassium sulfate as precipitant, lead generation lead sulfate potassium double salt precipitation with bismuth, arsenic, antimony, tin, iron, copper, zinc, aluminum, cobalt, nickel and other interference ions separation, precipitation with sodium acetate - acetic acid leaching, xylenol orange as the indicator, Na2EDTA titration method to determine the lead. Test to optimize the measurement condition, the optimum conditions, the amount of sulfuric acid (1 1) for 7 ml, the dosage of potassium sulfate for 5 g, boil for 5 min, when precipitation aging time is 2 h, 50 g/L EDTA addition amount to 10 ml, tartaric acid dosage is 0.5 g, the lead recovery is 99.70% ~ 100.65%. The experimental method was applied to the determination of lead in the complex high-bismuth materials. The sample BY0111-1 was consistent with the given value, and the relative standard deviation (n=11) RSD was 0.20% ~ 0.23%, which met the production test requirements.