Chromatographic separation of platinum group metals from simulated high level liquid waste using macroporous silica-based adsorbents

To separate platinum group metals (PGMs) from high level liquid waste, three novel macroporous silica-based adsorbents, namely, (Crea+Dodec)/SiO₂-P, (Crea+TOA)/SiO₂-P and (MOTDGA+TOA)/SiO₂-P, were synthesized by introducing extractants Crea (N',N'-di-n-hexyl-thiodiglycolamide), TOA (Tri-n-octylamine), MOTDGA (N,N'-dimethyl-N,N'-di-n-octyl-thiodiglycolamide) along with theirs modifier, Dodec (n-dodecyl alcohol), into 50μm diameter SiO₂-P particles by impregnation. Chromatographic separation of PGMs from simulated high level liquid waste was investigated by column method. It was found that 100% of Pd(II) and Re(VII) could be eluted out from simulate HLLW in 3.0M HNO₃ solution using three adsorbents. For Ru(III) and Rh(III), high temperature has distinct effect on the adsorption rate and a further study for Ru(III) and Rh(III) is necessary to separate them from HLLW completely. In all six column experiments, a relatively satisfactory chromatographic separation operating for PGMs from simulated HLLW was obtained using (Crea+TOA)/SiO₂-P adsorbent packed column at 323K.