EDTA滴定法在氰化液体钙含量测定中的应用

Application of EDTA titration in calcium determination of liquid cyanide

由于氰化液体的特殊性,其成分组成相当复杂。利用不同的消除方法进行掩蔽处理,程序繁杂,操作时间长,并且结果不易掌控。本方法用适当的酸处理氰化液体,破坏氰化液体中氰的络合物并赶除氰化氢后,在pH=6～9时,用六次甲基四胺和铜试剂沉淀分离干扰元素,然后用盐酸羟胺还原微量锰为低价而消除干扰,用三乙醇胺掩蔽残留的微量铝、铁等,在pH=12～12.5时,以钙试剂为指示剂,用EDTA标准溶液滴定钙,从而计算出钙的含量。结果表明:相对标准偏差RSD=0.26%,小于一般滴定操作要求的0.30%,钙的回收率在98%～99%。

The components of cyanide liquid are complex due to its specificity. The process of using different ways to eliminate masking treatment is cumbersome, long-running and difficult to control. This method uses the proper acid to treat the cyanide liquid. The cyanide complex is destroyed and hydrogen cyanide is eliminated. At the pH =6 ～ 9, the interference elements are separated using six methyl tetramine and copper reagent precipitate. At the pH=12 ～ 12. 5, with calcium reagent as the indicator, with EDTA standard solution titration of calcium, the calcium content is calculated and the results show that standard deviation RSD =0. 26%, is less than 0. 30% of the general titration operating requirements. The recovery rate of calcium is from 98% to 99%.