Experimental and theoretical study of anion-exchange preparative chromatography for neptunium: the first application to thorium(IV) and its equilibrium and kinetics.

In order to study equilibrium and kinetic parameters in anion-exchange chromatography for preparatory purpose, a quantitative model for nonlinear anion-exchange chromatography in porous media was constructed, by paying special attention to interstitial length along void structure (cm) distinguished from apparent length (cm*). Langmuir-type adsorption isotherm for thorium(IV), as a natural substitution for neptunium(IV), in 6 mol dm(-3) nitric acid to anion-exchanger MSA-1 (200-400 mesh) was investigated in batch-wise and chromatographic experiments. The equilibrium parameters determined by batch-wise experiments determined as k=2.4x10(2) mol(-1) dm3 s(-1) and s0=0.5 mol dm(-3) agrees very well with the values of k=222 mol(-1) dm3 s(-1) and s0=0.5 mol dm(-3) derived from fitting by the numerical calculation. Kinetic parameters of ks and D affect band profile similarly, thereby maximum value of each parameter was evaluated as ks=1.3 mol(-1) dm3 s(-1) and D=9x10(-4) cm2 s(-1) by the numerical calculations.