ALGINATE POLYELECTROLYTE IONOTROPIC GELS .15. PHYSICOCHEMICAL PROPERTIES OF URANYL ALGINATE COMPLEX ESPECIALLY THE CHEMICAL-EQUILIBRIUM ANDELECTRICAL-CONDUCTIVITY RELATED TO THE COORDINATION GEOMETRY

The heterogeneous equilibrium for exchange of UO22+ counter-ions in ur anyl alginate exchange resin by H+ ions has been investigated using ti trimetric and spectrophotometric techniques. The thermodynamic equilib rium constant was found to be 15.51 +/- 0.33 at 25-degrees-C. The elec trical conductivity of uranyl alginate in the form of circular discs h as been examined as a function of temperature. The Arrhenius plot of l og delta versus 1/T showed a complicated behaviour where three regions of conduction were separated by two distinct transition zones. This b ehaviour was interpreted by the transfer of electrons from alginate to the cross-linked uranyl ion with formation of free radicals and urani um ions of lower oxidation states in a sequence, followed by dimerizat ion of these radicals in the final stages. The X-ray diffraction patte rn indicated that the uranyl alginate complex is amorphous in nature. Infrared absorption spectra indicated the presence of UO22+ chelated t o the alginate macromolecular chains, and displayed gamma(a) CO2 and g amma(s) CO2- in the ranges of 1591 and 1410 cm-1 respectively. Two geo metrical structures for chelation of UO22+ with the functional groups of alginate macromolecules have been suggested.