[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.