EDTA滴定法测定氧化锌浸出渣中铅含量

提出了一种采用EDTA滴定法测定含铁、硅较高的氧化锌浸出渣中铅的分析方法。将试样用盐酸和硝酸溶解, 加入氟化铵分解渣料中的硅酸盐, 使包裹在硅酸盐中铅全部溶解出来, 然后加入硫酸使铅形成硫酸铅沉淀, 过滤, 使铅与锌、铁等易溶于硫酸的共存元素分离。用乙酸-乙酸钠缓冲溶液溶解硫酸铅, 加入抗坏血酸掩蔽少量铁, 以二甲酚橙为指示剂, 在pH 5～6的条件下, 用EDTA标准溶液滴定溶液至亮黄色为终点。样品测定结果的相对标准偏差在0.23%～0.76 %之间, 平均加标回收率为100.2%。

Determination of lead in zinc oxide leaching residue by EDTA titrimetry

An analytical method was proposed for the determination of lead in zinc oxide leaching residue with higher iron and silicon by EDTA titrimetry. The sample was dissolved in hydrochloric acid and nitric acid, then ammonium fluoride was added to decompose the silicates and completely dissolve lead enclosed in the silicates. Sulfuric acid was added to form lead sulfate precipitate, which was filtered to separate lead from other coexisting elements liking zinc and iron soluble in sulfuric acid. Acetic acid-sodium acetate buffer solution was used to dissolve lead sulfate and ascorbic acid was added to mask the small amounts of iron. With xylenol orange as the indicator, at pH 5-6, EDTA standard solution was used to titrate the solution into the color of bright yellow as the end. The relative standard deviation of determination results was in the range of 0.23%-0.76% and the average recovery was 100.2 %.