Abstract：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.
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