A spectroelectrochemical study of the technetium(IV)/technetium(III) couple in bicarbonate solutions

Spectroelectrochemistry at an optically transparent electrode, in conjunction with controlled potential coulometry, has been used to study the Tc(IV)/Tc(III) redox couple in aqueous bicarbonate solutions. The complexation provided by bicarbonate/carbonate ions was found to stabilize both Tc(IV) and Tc(III). The uv–visible absorption spectra for technetium(III) and technetium(IV) carbonate complexes are described. The redox potential for the Tc(IV)/Tc(III) couple, as well as the number of electrons, the number of carbonate groups, and the number of hydroxyl groups exchanged during the redox process in bicarbonate media are reported.