DETERMINATION OF THE OXIDATION STATE OF RHENIUM IN RHENIUM-MDP(HEDP)

The oxidation state of rhenium in Re MDP(HEDP) is studied by the method of extraction and potential titration. The experiment results are shown as follows: (1) As the pH of Re MDP reaction system reduced, the average oxidation state of rhenium droped. Re MDP of low valence is oxidized to Re(Ⅴ) MDP when it is titrated by I 3 - at pH 2.0; (2) The oxidation state of rhenium in Re HEDP is mostly +4 valence. The Re(Ⅳ) HEDP is oxidized to Re(Ⅴ) HEDP when it is titrated by I 3 - at pH 2.5; (3)ReO 4 - is only reduced by Sn 2+ in the reduction system of Vc+Sn 2+ , but Vc is oxidized earlier than Sn 2+ when it is titrated by I 3 -.