酸化ニッケル中の介在金属ニッケルの定量

概要

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The decomposition condition of metallic nickel in nickel oxide by the bromine methanol solution was studied. As a result, it was made clear that the decomposition time of 20 sec and the temperature of 2030°C were suitable and the water content up to 4% was permissible when the bromine concentration was 4% (v/v) in methanol. Above this concentration, nickel oxide started to dissolve. Three types of nickel oxide are known, green (burned at 1000°C), grey (800°C) and black(500°C). The solubility of black sample differs from others extraordinarily. The black one is only decomposed with the bromine methanol solution even if the bromine concentration is 1%. It may be caused by its poor crystallization. For the decomposition of the metallic nickel in practical samples (for example Cuban green nickel oxide) the following method is recommended. The pulverized sample(0.3 g, about 200 mesh) is decomposed with 50 ml of the bromine methanol solution (bromine 4%) for 20 sec at room temperature. After filtration 5 ml of conc HCl is added to the solution, which is then heated to dryness on a water bath. A few drops of HNO3 are added and the dry deposit is dissolved in water. The nickel ion in an aliquot of the solution is determined by the Ce-EDTA substitution titration method. The proposed method was superior to the mercuric chloride decomposition method (with dimethylglyoxime colorimetric) or X-ray diffractometry.
社団法人日本分析化学会の論文