EDTA滴定法测定含铋铅精矿中铅

国标方法测定铋含量高的铅精矿中的铅存在铋干扰消除不好,步骤繁琐等问题。实验通过用盐酸、硝酸和硫酸溶解样品,再用氢溴酸处理除去砷、锑和锡,以酒石酸络合大部分的铋,过滤硫酸铅,硫酸洗液洗涤后将硫酸铅沉淀连同滤纸合并一起,加入45mL醋酸-醋酸钠溶液并煮沸5min后,用水稀释至150mL,依次加入5mL柠檬酸钠溶液、4滴二甲酚橙溶液和2mL硫代乙醇酸(1+99)以消除铋干扰,EDTA滴定法测定铅含量。通过步骤优化,起到了对滤液中铅量的系统偏差修正作用,硫酸铅沉淀连同滤纸一起溶解滴定,无需单独测定滤液、滤渣,并将硫酸铅沉淀放置时间缩短为1h。经国家标准物质GBW07167和标样BY0111-1验证,结果与认定值及国标方法的测定值吻合;实验方法铅测定结果的相对标准偏差(RSD,n=12)分别为0.15%和0.09%。

Determination of lead in bismuth-containing lead concentrate by EDTA titration method

The determination method of lead in lead concentrate with high content bismuth by national standard method has some problems such as difficulty in interference elimination and complicated operation steps. The sample was dissolved with hydrochloric acid, nitric acid and sulfuric acid. Then arsenic,antimony and tin were removed by hydrobromic acid treatment. Most of bismuth was complexed with tartaric acid. The lead sulfate was filtrated followed by washing with sulfuric acid solution. The lead sulfate precipitate together with filter paper was boiled in 45 mL of acetic acid-sodium acetate solution for 5 min. After dilution to 150 mL with water, 5 mL of sodium citrate solution, 4 drops of xylenol orange solution and 2 mL of mercaptoacetic acid (1+99) were added to eliminate the interference of bismuth. The content of lead was finally determined by EDTA titration. The systematic deviation of lead content in filtrate was modified by procedure optimization. The lead sulfate precipitate together with filter paper was dissolved and titrated,so the single determination of filtrate and residue was not required. Moreover, the placing period of lead sulfate precipitate was shortened to 1 h. The proposed method was verified using national certified reference material GBW07167 and standard sample BY0111-1. The found results were consistent with the certified values and those obtained by national standard method. The relative standard deviation (RSD, n=12) was 0.15% and 0.09%, respectively.