火焰原子吸收光谱法间接测定氧化锌烟尘中氯

以稀硝酸溶解样品,然后向样品溶液中加入过量Ag⁺标准溶液,溶液中的微量Cl^-会与定量的Ag⁺形成氯化银胶体,加热煮沸溶液使氯化银胶体迅速凝聚并完全沉淀,采用火焰原子吸收光谱法测定滤液中剩余的Ag⁺量,通过换算间接得出氧化锌烟尘中的氯含量。讨论了共存离子的干扰、试样溶解条件、沉淀反应时间和测定介质,确定了最佳实验条件。采用实验方法测定烟化炉氧化锌烟尘和回转窑氧化锌烟尘中氯的含量,测得结果与氯化银比浊法基本一致,相对标准偏差(n=5)为0.65%～0.89%,回收率为99%～101%。

Indirect determination of chlorine in zinc oxide dust by flame atomic absorption spectrometry

The sample was dissolved in diluted nitric acid. Then, excessive Ag⁺ standard solution was added into the sample solution. Trace Cl^- in sample solution would quantitatively reacted with Ag⁺ to form silver chloride colloid. The solution was heated and boiled to agglutinate rapidly and completely precipitate silver chloride colloid. The residual Ag⁺ content in filtrate was determined by flame atomic absorption spectrometry. Then, the content of chlorine in zinc oxide dust could be indirectly obtained. The interference of coexisting ions, the dissolution conditions of sample, the reaction time of precipitation and determination medium were discussed to obtain the optimal experimental conditions. The proposed method was applied to the determination of chlorine content in zinc oxide dust of fuming furnace and rotary kiln. The results were basically consistent with those obtained by silver chloride turbidimetry. The relative standard deviations (RSD, n=5) were 0.65%-0.89%. The recoveries were between 99% and 101%.