水酸化鉄沈澱に対するコバルト共沈量の測定(第1～2報)

Solutions containing various percentages of ferric chloride and cobalt chloride, including radioactive cobalt-60, were made slightly acid with hydrochloric acid, and treated with zinc oxide suspended in water until the required pH for the coagulation of hydrous ferric oxide was reached. The precipitate was dissolved in hydrochloric acid, made strongly alkaline with sodium hydroxide, filtered, washed with water, dried, and weighed as Fe2O3 and Co3O4, from which the radioactivity was estimated. The amount of cobalt coprecipitated was determined by comparing it with the radioactivity of the standard samples. The same determination was carried out by a colorimetric method using nitroso-R-salt, and a similar result was obtained. It was found that the actual amount of coprecipitation with hydrous ferric oxide increases with an increase of the amount of cobalt added, however, the lower the ratio of cobalt included, the greater is the ratio of the amount of coprecipitation referred to the amount of cobalt included. The loss of cobalt is more than 1% when the content of cobalt is less than 3%, and less than 1% when the content of cobalt is more than 3%.Hydrochloric acid solutions containing various parts of ferric chloride, cupric chloride and cobalt chloride, including radioactive cobalt-60, and sulfuric acid solutions containing various parts of ferric sulfate and cobalt sulfate, including radioactive 60CoSO4, were treated respectively, with zinc oxide.The amount of cobalt coprecipitated was determined by measuring the radioactivity of cobalt-60.Considerably large amount of cobalt was found to be coprecipitated in the presence of sulfuric acid or cupric chloride compared with the case of hydrochloric acid solution.