硝酸银自动电位滴定法测定铜电解液中氯离子时稳定剂的影响

Influence of stabilizer on determination of chloride ion in copper electrolyte by silver nitrate automatic potentiometric titration

针对电位滴定法测定氯电位较不稳定的特点，建立了小剂量异丙醇作为稳定剂，自动电位滴定法测定铜电解液中氯离子含量的方法。确定的实验方法如下：准确移取10.00mL铜电解液样品于50mL烧杯中，控制反应温度为20～30℃，加入2mL异丙醇，加水至5OmL左右，将银复合电极和滴头冲洗干净插入待测液中，选择搅拌器转速为625r／min，用1.0100moL／L硝酸银标准溶液进行滴定。干扰试验表明，铜电解液样品中的硫酸和铜基体及其他共存元素对氯离子测定的影响可忽略。将实验方法用于铜电解液实际样品中氯的测定，测得结果与比浊法基本一致，相对标准偏差（RSD，n=5）不小于0．74％，回收率为98％～102％。

The potential was not stable in determination of chloride ion by potentiometric titration.To solve this problem,a determination method of chloride ion content in copper electrolyte was established by automatic potentiometric titration with small dose isopropanol as stabilizer.The experimental method was described as follows:10.00 mL of copper electrolyte sample was accurately transferred into 50 mL beaker;the reaction temperature was controlled at 20-30°C;after adding 2mL of isopropanol,the solution was diluted with water to about 50mL;after the silver combination electrode and dropper were washed with water and then inserted into testing solution,the rotate speed of stirrer was control at 625r/min;finally,the solution was titrated with 0.010 0moL/L silver nitrate standard solution.The interference test indicated that the influence of sulfuric acid,copper matrix and other coexisting elements in copper electrolyte sample on the determination of chloride ion could be ignored.The proposed method was applied to the determination of chloride ion in copper electrolyte actual sample.The results were basically consistent with those obtained by turbidimetry.The relative standard deviation(RSD,n=5)was less than 0.74%.The recoveries were between 98% and 102%.