Thin layer spectroelectrochemical (RVC-OTTLE) studies of pertechnetate reduction in acidic media

The electroreduction of the pertechnetate ions has been examined in sulfuric acid solutions (0.5–4 M) using optically transparent thin layer spectroelectrochemical (RVC-OTTLE) cell. Soluble Tc(III), TcO(2+) and [Tc(μ-O)(2)Tc](3+/4+) species with absorption bands at 420–450, 400, and 502 nm, respectively, were found to be formed during the reduction of TcO(4) (−) ions. The strongly acidic medium was found to stabilize technetium ionic forms with lower oxidation states. Spectroelectrochemical measurements performed in 4 M H(2)SO(4) show different stability of dimeric structure of Tc(III, IV) and simple TcO(2+) ions. The monooxotechnetium(IV) ions can be electrooxidized at potentials lower than 0.6 V versus Ag,AgCl((sat.)) while dimeric structures of Tc, [Tc(μ-O)(2)Tc](3+/4+), are electrooxidized to pertechnetate ions at potentials higher than 0.8 V versus Ag,AgCl((sat.))