Actinide coordination sphere in various U, Np and Pu nitrato coordination complexes

Waste management of nuclear fuel represents one of the major environmental concerns of the decade. To recycle fissile valuable materials, intimate knowledge of complexation mechanisms involved in the solvent extraction processes is indispensable. Evolution of the actinide coordination sphere of AnO₂(NO₃)₂TBP-type complexes (An = U, Np, Pu; TBP = tributylphosphate) with the actinide valence state have been probed by XAS at the metal L_III edge. Dramatic changes in the actinide coordination sphere appeared when the An(VI) metal is reduced to An(IV). However, no significant evolution in the actinide environment has been noticed across the series UO₂²⁺, NpO₂²⁺ and PuO₂²⁺.