Reduction of pertechnetate ions in nitric acid solutions by hydrazine

Reduction of pertechnetate ions in nitric and perchloric acid solutions has been studied by UV and visible spectroscopy. At [HNO3] approximately less than or equal to 8 M TcO4- reduction proceeds up to nitrate complexes of Tc(IV) via the intermediate stage Tc(V). At [HNO3] > 8 M the reduction reaches only up to Tc(V) which has been isolated in the form of a nitrate complex of the composition TcO(NO3)3.H2O. It has been noted that two-electron reduction in accordance with the reaction TcO4- + N2H5+ → Tc(V) + N2 + 2H2O + H+ is the stage that limits the total TcO4- reduction rate. The mechanism of the subsequent reactions has been discussed