电位滴定法测定钒电池电解液中硫酸根

钒电池电解液的酸根组成和浓度会严重影响电池的效率,需要准确地测定各种酸根的浓度,以便及时地进行调节。重量法是测定硫酸根的经典方法,但操作步骤繁琐、耗时较长,不能满足过程控制调整的要求。实验采用EDTA络合钒,再以NaOH标准滴定溶液利用酸碱滴定法测定溶液中总氢离子浓度,根据样品中不同价态钒的浓度通过计算即可得到样品中硫酸根浓度,实现了电位滴定法对含钒电解液中硫酸根离子的检测。实验对EDTA加入量、EDTA加入形式进行优化。分别按照实验方法和重量法测定1个钒电池电解液中硫酸根,两种方法无显著性差异;按照实验方法对两个钒电池电解液样品中硫酸根进行加标回收试验,回收率为98.9%~100.0%;按照实验方法测定3个钒电池电解液样品中硫酸根,结果的相对标准偏差(RSD,n=5)为0.13%~1.2%。分别使用实验方法和重量法测定含有不同价态钒的3个钒电池电解液中硫酸根,结果相吻合。

Determination of sulfate in vanadium battery electrolyte by potentiometric titration

The composition and concentration of acid radicals in vanadium battery electrolyte can greatly influence on the battery efficiency. The concentrations of various acid radicals should be accurately determined for real-time adjustment. The gravimetry is the classic method for the determination of sulfate, but the operation is tedious and time-consuming, which cannot meet the adjustment requirements of process control. After complexing of vanadium with EDTA, the content of total hydrogen ions in solution was determined by acid-base titration using NaOH standard titration solution. According to the concentration of vanadium with different valences, the concentration of sulfate in sample could be calculated, thus realizing the determination of sulfate in vanadium electrolyte by potentiometric titration. The dosage and addition method of EDTA were optimized in experiments. The content of sulfate in one sample of vanadium battery electrolyte was determined according to the experimental method and gravimetry. There was no significant difference between two methods. The recovery test of sulfate in two samples of vanadium battery electrolyte was conducted according to the experimental method. The recoveries were between 98.9% and 100.0%. The concentration of sulfate in three samples of vanadium battery electrolyte was determined according to the experimental method. The relative standard deviations (RSD, n=5) of results were in range of 0.13%-1.2%. The concentration of sulfate in three samples of vanadium battery electrolyte with different valences of vanadium was determined according to the experimental method and gravimetry, respectively. The found results were consistent between two methods.