EDTA滴定法测定含锌物料中氧化锌

Determination of Zinc Oxide Content in Zinc Containing Materials by EDTA Titration

采用氯化铵-氨水体系溶解试样,干过滤后,向移取的滤液中加入氯化钡和硫酸共沉淀铅离子,过滤分离硫酸铅沉淀,向滤液中加人抗坏血酸、氟化钾、硫代硫酸钠等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氧化锌、水溶性锌和镉合量,扣除由原子吸收光谱法测得的水溶性锌量和镉量,即为氧化锌量。对总氨浓度、氯化铵-氨水浓度比、溶液加入量、搅拌时间、共存离子干扰、精密度等进行了实验,建立了EDTA滴定法测定含锌物料中氧化锌物相的分析方法。实验证明,氧化锌含量在24%~83%时,方法精密度(RSD)为0.25%~0.54%,加标回收率在99%~104%,完全满足含锌物料中氧化锌的测定要求。

A new method for the determination of zinc oxide in zinc containing material was established. The sample was dissolved with ammonium chloride-ammonia, and after dry filtering, barium chloride and sulfuric acid were added into the filtrate to precipitate lead ions. The lead sulfate precipitation was separated by filtering. Masking agent such as ascorbic acid, potassium fluoride and sodium thiosulfate were added into the filtrate to mask the small amount of interference ions. In the eth＇anoie acid-sodium acetate buffer solution with pH=5~6 and with xylenol orange as the indicator, the solutions were titrated with Na2EDTA standard solution. The total amount of zinc oxide, water soluble zinc and cadmium in the filtrate were obtained from the titration results. The zinc oxide content was calculated by deducting the amount of cadmium and water soluble zinc, which were separately determined by flame atomic absorption spectrometry, from the total amount of zinc oxide, water soluble zinc and cadmium. Various experimental conditions and factors, such as total amount of ammonium, ratio of ammonium chloride to ammonia, solution addition amount, stirring time, co-existing ions interference, and precision, etc. , were studied. An analytical method for the determination of zinc oxide phase in zinc containing materials by EDTA titration method was established. The effect of various experimental conditions was studied in detail. The results showed that the precision （RSD） of this method was between 0.25% and 0.54% and the recovery rate was in the range of 99% to 104%, when the zinc oxide content was between 24% and 83%. This method can meet the requirement for the determination of zinc oxide content in zinc containing materials.