双水相体系中镍的光谱性能及测定

本文研究了聚乙二醇 硫酸铵 锌试剂双水相体系中镍的光谱性能及测定。结果表明 ,该体系显色的最佳酸度为pH 8 5 ,络合物光谱最大吸收波长位于 6 75nm ,摩尔吸光系数ε=1 2 6× 10 4 L·mol- 1 ·cm- 1 ,Ni(Ⅱ )线性范围为 0 2～ 2 4 μg·mL 1 。Ni(Ⅱ )和锌试剂络合比为 1∶3。与一般水溶液光度法比较 ,络合物光谱最大吸收波长红移 10nm ,络合比增加 (由 1∶1到 1∶3) ,显色反应的灵敏度和稳定性提高。该方法用于铝合金中镍的测定 ,获得满意结果。

Study on the Determination and Spectral Characteristics of Nickel for Two-phase Aqueous Systems

The determination and spectral characteristics of nickel for polyethylene glycol-ammonium sulfate-zincon two-phase aqueous systems are studied in this paper. It is shown that the composition ratio of nickel to zincon is 1:3 at pH 8.5 and the maximum absorption is at 675 nm. The apparent molar absoptivity is epsilon = 1.26 x 10(4) L.mol-1.cm-1, and the Beer's law is obeyed in the range of 0.2 to 2.4 micrograms nickel per mL. Compared to a general water phase spectrophotometry, the maximum absorption wavelength of the complex shifts to the red wavelength, the molar ratio of metal ion to reagent increases, and the sensitivity and selectivity of the method increase. In addition, the presence of large amounts of other ions in the sample does not interfere with the determination of Ni(II) in this extraction process, because the PEG-Na2SO4-H2O solvent system is inflammable, nonvolatile and nontoxic. Low price and ability to recycle PEG make it an economic procedure. Environmental pollution is reduced. Moreover, the methods are more convenient and more rapid. The method has been applied to the determination of nickel in aluminium alloy with satisfactory results.