微分脉冲伏安法测定硫酸锌溶液中铊

Determination of Thallium in Zinc Sulfate Solution by Differential Pulse Voltammetry

研究了微分脉冲伏安法测定复杂硫酸锌溶液体系中的铊。讨论了伏安图的形成、测定底液和pH值的选择。结果表明:在醋酸介质(pH=4.5±0.2)中,加入适量EDTA、聚乙二醇6000和抗坏血酸的测定体系,采用微分脉冲伏安法可直接测定铊。方法检出限为1.0×10-8g/L,千倍浓度的8种阳离子共存或单独存在时均不干扰测定。方法用于湿法炼锌中上清、一段净化后液、二段净化后液、电积新液、电积废液中铊的测定,相对标准偏差RSD分别为1.6%,2.5%,3.3%,8.3%,4.9%,铊加标回收率为98.4%～102.2%。方法灵敏、简单、快速,用来测定湿法炼锌各阶段硫酸锌溶液中的铊,结果满意。

A method for determination of thallium in complicated zinc sulfate solution system by differential pulse vohammetry was studied. The formation of vohammetry graph, base solution determination and the choice of pH value were discussed. The results showed that in acetic acid medium （pH=4.5±0.2）, by addition of small amount of EDTA, polyethylene glycol （PEG） 6000 and ascorbic acid into the analysis system, the thallium can be directly determined by differential pulse vohammetry. The detection limit of this method was 1.0X 10^-8 g/L. There was no interference detected which was caused by the eight cations either coexisting or individually existing in the solution with the concentration of 1 000 fold. This method has been successfully used to determine thallium in the middle-supernatant, the liquid after first purification, the liquid after the second purification, the fresh eleetrowinning liquid and the aged electrowinning liquid which were generated during the hydrometallurgy process of zinc. Relative standard deviation are less than or equal to 1.6%, 2.5%, 3.3%, 8.3%and 4.9%, and the recoveries of thallium are in the range of 98.4%～102.2%. The method is sensitive, simple and rapid.