» Uranium Extraction By Amorphous Modified Titanium And Zirconium Phosphates

Uranium Extraction By Amorphous Modified Titanium And Zirconium Phosphates

V.V. Strelko, O.I. Zakutevsky, I.Z. Zhuravlev,T.S. Psareva, V.A. Kanibolotsky

Institute for Sorption and Endoecology Problems, Ukrainian National Academy of Sciences, General Naymov st. 13, 03680 Kiev, Ukraine

Designed in Institute of Sorption and Endoecology Problems amorphous granulated modified titanium and zirconium phosphates differ from crystalline types of phosphates. Due to the optimal size of granules and developed porosity they can be utilized in sorption columns with low hydrodynamic drag force, that uncloses perspectives of building on the basis of these ion exchangers of effective sorption technologies of extraction, concentrating and high effective purification of materials [1,2].

The literary data testify that the real exchange capacities of amorphous titanium and zirconium phosphates do not exceed half from the theoretically calculated quantities.

In the present work we have made the attempt to increase ion-exchange capacity and porosity of amorphous titanium and zirconium phosphates for score of introduction in working reagents mixture of tervalent metals (Al3+, Fe3+) salt solutions. It was supposed, that the tervalent metal cations will play a role of template-cations, linking part of phosphate groups of ion exchangers during their synthesis. When washing of such phosphate hydrogels the tervalent cations - templates should be washed from gel in solution, owing to what the part of free phosphate groups, bounded with titanium and zirconium should be higher, than for ion-exchangers, obtained by an ordinary method. It is possible to suggest, that the ion-exchangers of such type will show increased ion-exchange capacity relatively to three-valent ions – templates, and also towards uranium ions, showing high affinity to phosphate ligands [3]. We have comprehensively investigated a uranium sorption from water solutions of uranyl acetate UO2 (CH3COO)2·2Н2О by the modified with Al3+ or Fe3+ ions hydrogenous and potassium forms of TiP and ZrP. The kinetics of uranium uptake by all samples testifies to two-stage character of sorption process: a

rapid first stage, during which sorb more than 85 % of uranium and time-lagged second stage when 15 % of stayed uranium are extracted.

The isotherms of uranium sorption by modified TiP and ZrP, testify that sorption capacity of ion exchangers in the hydrogenous form is much higher than one in the potassium form as a result of uranyl ions high affinity to a ion exchangers surface.

Thus, the titanium and zirconium phosphates in the hydrogenous form, modified with Al3+ or Fe3+ ions in the process of gelation are characterized by heightened values of specific surface.

These sorbents show high ion-exchange capacity up to 1,7 meq/g (229,5mg/g) relatively to uranil ions. Ion exchange capacity weakly depends from рН in a broad enough interval.

Therefore it is possible to think, that the designed sorbents are quite perspective for purification of underground, artesian 15, and also utilized waters of Atomic Power Plants 16 from uranium, transuranium elements. Actinides can be concentrated for analytical definition purposes from acid complicate composition solutions too.