Study on separation of platinum group metals from high level liquid waste using macroporous (MOTDGA-TOA)/SiO2-P silica-based absorbent

To research recovering of platinum group metals (PGMs) from high level liquid waste (HLLW) by macroporous silica-based adsorbent, (MOTDGATOA)/SiO ₂-P was developed by impregnating two extractants of N,N'-dimethyl-N,N'-di-n-octyl-thiodiglycolamide (MOTDGA) and tri-n-octylamine (TOA) into a silica/polymer composite support (SiO₂-P). Adsorption of Ru(III), Rh(III) and Pd(II) were investigated in simulated HLLW by batch method. The adsorbent showed good uptake property for Pd(II). In addition, the combined use of MOTDGA and TOA improved adsorption of Ru(III) and Rh(III) better than the individual use of them. The usability of adsorbent in radiation fields was further confirmed by irradiation experiments. The adsorbent remained to have the uptake capability for PGMs at least absorbed dose of 100 kGy, corresponding with one adsorbed by the adsorbent, and showed good retention capability for Pd(II) even at the absorbed dose of 800 kGy. The chromatographic separation of metal ions was demonstrated with the adsorbent packed column, there is no influence of Re(VII) (instead of Tc) on the excellent separation behavior of Pd(II).