硝酸银光度法测定工业硫酸锌中痕量砷

来源期刊：冶金分析2010年第6期

论文作者：江秋月

文章页码：66 - 68

关键词：工业硫酸锌； 砷； 硝酸银； 分光光度法

Key words：industrial zinc sulfate； arsenic； silver nitrate； spectrophotometry

摘    要：以聚乙烯醇为介质,硝酸银为显色剂,在乙醇体系中,采用分光光度法测定了工业硫酸锌中痕量砷。在1.8～3.6mol/L酸度下,硫酸锌中砷被锌粒还原成砷化氢气体逸出,用硝酸银-聚乙烯醇-乙醇溶液作为砷化氢的吸收剂,砷化氢将硝酸银还原成单质胶态银,在聚乙烯醇的作用下显黄色,其最大吸收峰位于400nm波长处,表观摩尔吸光系数为2.2×10⁵ L·mol^-1·cm^-1,砷的质量浓度在0～0.6mg/L范围内符合比尔定律。方法用于工业硫酸锌样品的分析,回收率在99%～103%之间,相对标准偏差为1.7%～2.4%,结果同DDTC-Ag光度法的测定结果相一致。

Abstract: In ethanol system, trace arsenic in industrial zinc sulfate was determined by spectrophotometry using polyvinyl alcohol as medium and silver nitrate as coloring reagent. The results showed that under the acidity of 1.8-3.6 mol/L, the arsenic in zinc sulfate was reduced to arsenic hydride gas by zinc particle, and after the released arsenic hydride gas was absorbed by silver nitrate-polyvinyl alcohol-ethanol solution, the silver nitrate was reduced by arsenic hydride to elemental colloid silver, which was yellow in the presence of polyvinyl alcohol. The maximum absorption wavelength was 400 nm, and the apparent molar absorptivity was 2.2×10⁵ L· moL^-1· cm^-1. Beer’s law was obeyed for arsenic over the mass concentration range of 0-0.6 mg/L. The method has been applied to the determination of arsenic in the industrial zinc sulfate. The recovery was in the range of 99%-103%, and the relative standard deviation (RSD, n=6) was 1.7%-2.4%. The determination results were consistent with those obtained by DDTC-Ag spectrophotometry.