Technetium electrodeposition from aqueous formate solutions at graphite electrode: Electrochemical study

Recovery of technetium from aqueous formate buffer solutions of ionic stren gth mu = 1.0 was studied in the pH interval from 1.6 to 7.5 at graphite cat hode in an electrolytic cell with separated compartments was studied, using cyclic voltammetry (CV) and inverse stripping voltammetry (ISV) techniques . It has been shown that Tc electrodeposition process becomes possible at t he potentials of graphite cathode E-cath. < -0.6 V/SCE. Tc recovery from so lution was found to increase with the growth of the electrolyte pH and with the shift of the cathode potentials towards negative values. Using ISV tec hnique the half-wave potential value of Tc electrodeposition process has be en determined as E-1/2 = -0.72 +/- 0.02 V/SCE and was pH independent in the interval pH = 3.46 - 7.32. Mechanism of electrodeposition, including Tc(VI I)/Tc(IV) reduction in the solution followed by Tc(IV) hydrolysis at the el ectrode surface with formation of hydrated Tc oxide cathodic deposit has be en proposed. The further precision of the Tc(VII) electrochemical reduction mechanism in formate buffer media and optimization of the electrodepositio n process seems to be possible using additional analytical facilities excep t electrochemical methods.