EDTA滴定法测定再生锌原料中的锌含量

采用氟化铵-盐酸-硝酸-硫酸分解样品,氨水沉淀分离铁、锰、铅等共存元素,滤液中加入掩蔽剂掩蔽少量干扰元素,在pH=5～6的乙酸-乙酸钠缓冲溶液中,以二甲酚橙为指示剂,用EDTA标准滴定溶液滴定。测得结果为锌、镉合量,扣除镉量,即为锌量。方法用于测定再生锌原料中锌,结果的相对标准偏差(RSD,n=11)为0.15%～1.0%。按照实验方法对再生锌原料样品进行加标回收实验,回收率为99.1%～102%。能满足日常对再生锌原料中锌含量的检测要求。

Determination of zinc content in regenerated zinc material by EDTA

The new determination method of zinc in regenerated raw material is established. Sample is decomposed by ammonium fluoride-hydrochloric acid-nitric acid-sulfuric acid, and the coexisting elements such as iron, manganese and lead are separated by ammonia water precipitation. A small amount of interfering elements were masked by adding a masking agent to the filtrate, and the zinc in the filtrate was titrated with EDTA standard titration solution in an acetic acid-sodium acetate buffer solution of pH 5-6, using xylenol orange as an indicator. The measured results combined with the amount of zinc and cadmium, and the amount of zinc is obtained by deduction the amount of cadmium. The relative standard deviations(RSD, n=11) of determination result were between 0.15% and 1.03%.The recoveries in samples of silver slag were between 99.1% and 101.6%.This method could meet the requirements of daily analysis of zinc content in regenerated zinc material.