PNNL

Abstract

Evaluation of suitability of Fe0, or zero valent iron (ZVI) for Tc sequestration paves the way to the iron-based waste form development and contributes to remediation of contaminated plumes and nuclear wastes disposal. Although reduction of 99Tc7+ with metallic iron and iron minerals has been studied, behavior of the system under the elevated Tc loading and at the equilibria with aerobic environment has not been investigated. Here we examine granular ZVI as a promising waste form material for reductive sequestration of 99Tc7+ and conduct comprehensive comparative analysis of iron mineral phases formation and transformation in the presence and absence of Tc. Our results indicate beneficial effect of concomitant Fe0 oxidative transformation on the reduction of TcO4- and its partial structural incorporation into magnetite, i.e. non-stoichiometric magnetite. Moreover, for the first time we report suppressed iron oxidation and retarded transformation of ferrihydrite into magnetite in the presence of Tc.