METHOD FOR DETERMINING FLUORIDE AND TETRAFLUOROBORATE IONS IN THEIR JOINT PRESENCE

Claims

A method for determining fluoride and tetrafluoroborate ions in their joint presence by a direct potentiometric method using a lanthanum fluoride ion-selective electrode and a reference electrode, including the construction of a calibration curve using standard solutions, wherein the construction of a calibration curve for the lanthanum fluoride ion-selective electrode is carried out using standard solutions of NaF with concentrations of 10 -6 -10 -2 mol / l and simultaneously carry out direct potentiometric measurement of tetrafluoroborate ions using a nitrate-selective electrode converted to tetrafluoroborate-selective form with a membrane made of polyvinyl chloride, quaternary ammonium base and dibutyl phthalate, and a reference electrode, including the construction of a calibration curve using standard solutions of KBF4 with concentrations of 10 -6 -10 -2mol / l, all electrodes are immersed in the analyzed solution containing electrolyte from a spent supercapacitor, washed from the cell in an ultrasonic bath or manually, characterized in that the washing time is 10 minutes, the analyzed electrolytes contain acetonitrile 75-85%, methylcyclopentyl ether 15-25%, the operating voltage is 2.7-3.0 V, charge-discharge cycles 10,000, or the analyzed electrolytes contain acetonitrile 75-100%, methylcyclopentyl ether 0-25%, the operating voltage is 3.5-4.0 V.