镉镍电池正极物质中钴含量的测定

Determination of cobalt content in positive material for Ni-Cd battery

镉镍电池正极物质中钴含量的测定 ,以前采用硫氰酸铵和钴形成兰色配合物 ,再用异戊醇萃取 ,经过吸光度测量 ,计算出钴含量 ,当钴和铁共有时 ,铁和硫氰酸铵生成红色配合物 ,一块被异戊醇萃取 ,对钴的测定带来干扰。为了消除铁的干扰 ,拟采用氨水和钴形成配合物 ,利用此配合物的颜色对钴作比色分析 ,探讨了镍、铁的干扰和氨水与钴形成配合物的条件。本方法的回收率为 95 %～ 10 2 % ,相对标准偏差≤ 2 .9% ,钴测定范围在 1%～ 10 %

Previously, cobalt content in the positive material of Ni Cd battery was determined by means of adding NH 4CNS and cobalt to form blue compound and extracting with(CH 3) 2CHCH 2CH 2OH.After photometry measurement, the content was calculated. However, when iron and cobalt co exist, iron react with NH 4CNS to form red compound, which is extracted by (CH 3) 2CHCH 2CH 2OH, and the reaction disturbed cobalt determinnation. To eliminate the disturbance, aqueous ammonia and cobalt was added to form compound, whose color is used for colorimetric analysis to determine cobalt content. The formation conditons of the compound made from cobalt and aqueous ammonia and the disturbance of iron and nickel were investigated. The recycling rate to the method is 95%-102% and its relative standard deviation is not more than 2.9%. Determination range of cobalt content by the method is 1%-10%.