Selective separations of Am(III)/Eu(III) using heterocyclic bistriazinyl phosphonate grafted zirconia and titania solid phase extractants

Surface functionalization of metal oxides with phosphonic acid monolayers by covalent bonding enables the generation of robust hybrid materials with enhanced separation properties. Mesoporous crystalline zirconia and titania serve as applicable inorganic supports with high thermal stability and resistance to oxidation, acidity and radiolysis. We have fabricated selective solid phase extractants that efficiently separate americium and europium from each other, via straightforward grafting of the zirconia and titania surfaces with N- and S-donor complexing agents, namely 2,6-bis-triazolyl-pyridine derivatives. Separation factors (Am/Eu) up to 13 were obtained in binary solution at pH 2 and preference for Am over Eu was observed even in Eu excess solution. These stable hybrid materials can be utilized for separation purposes without substantial degradation, providing advantageous reusability and a greener option in comparison to commonly used solvent extraction methods.