The immobilization of 99Tc in the environment has usually been achieved via reduction of the prevalent TcO4- anion to relatively insoluble TcO2Tc(IV) species. This species is then typically immobilized in glass or ceramic materials for long-term storage. Recently, our laboratory has been studying the use of small metal-oxide clusters called polyoxometalates (POMs) to act as both reducing agent and chelator for the 99Tc upon UV irradiation. The work presented here will discuss the use of both Keggin-type polyoxometalates and the semiconductor system TiO2 for the reduction of TcO4- to lower valent species. The degree of reduction of the Tc within the POM system is dependent on irradiation time and the heteroatom of the POM. The TiO2 system can reduce up to 95% TcO4- within 16 hours of irradiation. EXAFS and XANES show that technetium was reduced to the +4 oxidation state. The Tc, in both cases, is free in solution and bound to the surface of the POM and TiO2 in a pseudo-octahedral environment.

?Reduction of pertechnetate via metal oxide semiconductors

246th National Meeting (2013)

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