电位滴定法测定锂离子电池废料中钴

Determination of Cobalt in Lithium Ion Battery Waste by Potentiometric Titration Method

采用电位滴定法测定锂离子电池废料中钴含量。本文考察了溶样方法、共存元素干扰、柠檬酸铵-氯化铵-氨水溶液用量、铁氰化钾溶液用量及共存元素干扰等因素对测定的影响。研究发现:用盐酸和硝酸溶解试样,在柠檬酸盐存在的氨性溶液中,加入过量的铁氰化钾将钴(Ⅱ)定量的氧化为钴(Ⅲ),用钴溶液对过量的铁氰化钾进行电位滴定。对于低锰试样,锰(Ⅱ)也被铁氰化钾定量的氧化为锰(Ⅲ),测定结果为钴锰的合量,将锰含量校正为钴含量后减去即为试样的钴含量。对于高锰试样,需采用氯酸钾将锰(Ⅱ)氧化为二氧化锰后过滤分离消除锰干扰,对滴定液中锰含量校正和二氧化锰渣中钴含量进行补正。对实际废料测定结果表明:相对标准偏差不大于0.50%,加标回收率为99.7%~100.3%。

The content of cobalt in lithium ion battery waste was determined by potentiometric titration.The effects of sample dissolving method,interference of coexisting elements,amount of ammonium citrate ammonium chloride ammonia solution,amount of potassium ferricyanide solution and interference of coexisting elements on the determination were investigated.It is found that the sample is dissolved with hydrochloric acid and nitric acid,and the excess potassium ferricyanide is added to the ammonia solution in the presence of citrate to quantitatively oxidize Co(II) to Co(III).The excess potassium ferricyanide is potentiometric titrated with cobalt solution.For the low manganese sample,Mn(II) is also quantitatively oxidized to Mn(III) by potassium ferricyanide.The determination result is the combined amount of cobalt and manganese.The cobalt content of the sample is subtracted after the manganese content is corrected to the cobalt content.For high manganese samples,potassium chlorate should be used to oxidize Mn(II) into manganese dioxide,then filter and separate to eliminate manganese interference,and correct the manganese content in titrant and the cobalt content in manganese dioxide residue.The results show that the relative standard deviation is less than 0.50 %and the recovery is 99.7 %~100.3 %.