Recovery of ReO4− by weakly basic anion exchangers: Modeling of sorption equilibrium and rate

Equilibria and dynamics of rhenium uptake from nitrate, chloride and sulfate matrices using weak base anion exchangers have been studied. Gel-type IRA-67 containing tertiary amine groups and macroporous WP-1 containing primary, secondary and tertiary groups were used. Experimental equilibrium and batch kinetic data were correlated using various ion exchange and intra-particle diffusion models. For both exchangers, best correlation was found with the exchange/protonation model including Donnan exclusion and with the surface complexation model. Explicit models requiring no iterations are less accurate but correlate the data satisfactorily. Approximate solution of the Nernst-Planck model was found adequate for correlation of the uptake rates in base-form and fully protonated exchangers.