EDTA滴定法测定分银渣中的铅含量

采用氟化铵-盐酸-硝酸-高氯酸溶解样品,加入氢溴酸除去样品中的砷、锑、锡等共存元素,加入硫酸将样品中的铅转化为硫酸铅沉淀,通过过滤与其它元素分离,滴定前加入巯基乙酸掩蔽铋,在乙酸-乙酸钠缓冲体系下,以二甲酚橙为指示剂,建立了采用EDTA络合滴定法测定分银渣中铅含量的方法。实验方法用于测定分银渣中的铅含量,测定结果的相对标准偏差(RSD,n=11)为0.32%～0.90%,加标回收率为100%～102%。能够满足日常测定需求。

Determination of lead content in silver separating residue by EDTA titration method

The sample was dissolved with ammonium fluoride-hydrochloric acid-nitric acid-perchloric acid. The coexisting elements such as arsenic, antimony and tin were separated by acid-hydrobromic acid. Then, the sulphuric acid was added to promote the formation of lead sulfate precipitation, which was separated with the other elements by filtration. Before titration, mercaptoacetic acid was added into solution to eliminate the influence of bismuth. In acetic acid-sodium acetate buffer solution, the determination method of lead content in silver separating residue by EDTA titration was established by using xylenol orange as an indicator. The proposed method was used to determination of lead content in silver separating residue. The results showed that the relative standard deviations (RSD, n=11) was between 0.32% and 0.90%. The recovery rate of the determination method was between 99.98% and 101.91%. The optimized operation process is simple and satisfies the production requirements.