Method for measuring content of chlorine in mixed acid electrolyte through potentiometric titration

Abstract

The invention discloses a method for measuring content of chlorine in a mixed acid electrolyte through potentiometric titration. According to the method, the chlorine content of a to-be-measured solution is titrated by adopting a silver nitrate standard solution, a titration end point is judged according to change of electric potential in a titration process, and the content of chloride ions in a tested sample is calculated according to the volume of the consumed silver nitration solution. By means of sample dilution and addition of an appropriate amount of nitric acid in a sample processing process, on one hand, the influence of other acid radicals in the sample on the titration is eliminated; on the other hand, trivalent vanadium ions in the solution are oxidized into tetravalent vanadium ions through addition of nitric acid, so that complexing capacity between the vanadium ions and the chloride ions is reduced, and the reaction of titrating the chloride ions by silver nitrate is enabled to be more smooth and more stable. According to the chloride ion concentration obtained by the test, a chloride ion masking agent is added through calculation, and the content of trivalent vanadium and tetravalent vanadium in the solution is measured with a potassium permanganate-potentiometric titration method. The method effectively avoids disturbance of the chloride ions on the vanadium measurement process and is fast and accurate.

Description

technical field [0001] The invention relates to the technical field of material measurement, in particular to a method for determining the content of main components in a mixed acid electrolyte by potentiometric titration. Background technique [0002] As an emerging energy storage battery, vanadium battery has been widely used in the field of new energy in recent years. Electrolyte, as the main energy storage medium, is the main component of vanadium batteries. The composition and concentration of acid groups in the electrolyte solution will affect the stability, viscosity, and conductivity of the solution, and ultimately affect the efficiency of the battery. By controlling the composition and concentration of the acid, the performance of the electrolyte can be greatly improved. Therefore, it is necessary to accurately measure the concentration of various acid radicals in order to adjust them in time. Chloride ion is an important part of acid radicals, and its rapid and a...

AI Technical Summary

Problems solved by technology

[0003] Traditional methods for detecting chloride ion content, such as the silver method, are not suitable for solutions containing vanadium ions with obvious colors

[0004] In addition, use a strong oxidant, such as potassium permanganate to fix the chlorine-containing vanadium solution, because potassium permanganate can oxidize chloride ions. In the process of oxidizing tetravalent vanadium, the electrode potential change behavior of the solution changes. , the curve jitters in the trivalent vanadium oxidation region, and suddenly disappears in the tetravalent oxidation region, so the potassium permanganate titration method cannot be used to directly measure the trivalent and tetravalent vanadium content in the electrolyte of the chlorine-containing all-vanadium redox flow battery

As a result, when producing and using mixed acid electrolytes, the state of the solution cannot be accurately measured, and a method is urgently needed to measure the valence state of vanadium.

Images