用电位滴定法测定含锌硫化活性剂中锌含量

Determination of zinc ion content in zinc-containing curing activator by potentiometric titration

将含锌硫化活性剂直接溶解于盐酸溶液中,以乙二胺四乙酸二钠为滴定剂、铜离子选择电极为指示电极、银/氯化银为参比电极,采用电位滴定法测定含锌硫化活性剂中的锌含量。研究表明,硫酸铜的加入可增大滴定曲线的突跃范围,且铜离子选择电极在pH值为10的缓冲体系中灵敏度较高。采用电位滴定法测定2种含锌硫化活性剂中的锌离子含量及其回收率,并与原子发射光谱法进行比较,结果表明该两种硫化活性剂中锌离子含量回收率分别为100.13%和99.32%,且两种测试方法所得结果无明显差异,采用电位滴定法测定标准溶液中的锌离子含量并进行统计检验,结果显示测试值与标准值无明显差异,说明采用电位滴定法测定含锌硫化活性剂中锌含量可行有效。同时测定了混炼橡胶中硫化活性剂的锌离子含量,结果与理论计算值相近,故该方法同样适用于混炼橡胶中锌离子含量的测定。

Using Na2EDTA solution as titrant,copper ion-selective electrode as indicator electrode,Ag/AgCl electrode as reference electrode,zinc ion content in zinc-containing curing activator was determined by potentiometric titration.The results showed that the addition of copper sulfate solution could increase the titration-jump of zinc ion titration curve and copper ion-selective electrode was sensitive in buffer system with pH value 10.The contents and recovery rates of zinc ions in two kinds of zinc-containing curing activators were determined by potentiometric titration and compared with atomic emission spectrometry.The results showed that the recovery rates of zinc ions in the two kinds of curing activators were 100.13%and 99.32%respectively,and there was no significant difference in accuracy and precision between the two methods.Content of zinc ion in standard solution was determined by potentiometric titration method and verified statistically.The results showed that there was no significant difference between the test value and standard value,indicating that using potentiometric titration method to determine the zinc content in the zinc-containing curing activator was feasible and effective.At the same time,the contents of zinc ion in mixed rubbers were determined,which were similar to the theoretical calculation value.Therefore,the method was also suitable for the determination of zinc ion content in mixed rubber.