氯离子选择电极法测碳酸钴中Cl-含量

Determination of Cl-Content in Cobalt Carbonate by Chloride Ion Selective Electrode Method

碳酸钴中Cl-含量控制是衡量碳酸钴洗涤工艺稳定性的关键指标,常规检测Cl-的方法为硝酸银比浊法,但因钴离子的颜色干扰严重,造成分析结果不稳定不准确。本文采用氯离子选择电极方法来测量碳酸钴中的Cl-含量,通过离子强度剂用量实验、酸度调节剂选择和用量实验,酸溶法与水浸法对比实验,以及氯离子选择电极测量稳定性实验。总结出最佳分析条件:用5 mL硝酸(1+1)将碳酸钴全部溶解,5 mL硝酸钾作离子强度剂,20 mL柠檬酸三钠做酸度调节剂并络合钴离子,用离子计检测碳酸钴中Cl-含量。该方法精密度良好,标准偏差为0.005 7%,RSD为3.35%。该方法回收情况良好,回收率96.3%~103.3%。

The control of Cl-content in cobalt carbonate is a key index to measure the stability of cobalt carbonate washing process. The conventional method to detect Cl-ion is silver nitrate turbidimetric method. However, due to the serious color interference of cobalt ions, the analysis results are unstable and inaccurate. In this paper, the Cl-content in cobalt carbonate was measured by the method of chloride ion selective electrode. The ion strength agent dosage experiment, acidity regulator selection and dosage experiment, acid solution method and water immersion method comparison experiment, as well as the chloride ion selective electrode stability test were conducted. An optimal analysis conditions is summarized: 5 mL nitric acid(1+1) was used to dissolve all cobalt carbonate, 5 mL potassium nitrate was used as ionic strength agent, 20 mL trisodium citrate was used as acidity regulator and the cobalt ion was complexed, and the Cl-content in cobalt carbonate was detected by ion meter. The method had good precision, the standard deviation was 0.005 7%, the RSD was 3.35% and the recovery rate was 96.3%~103.3%.