Adsorption properties and behavior of the platinum group metals onto a silica-based (Crea + TOA)/SiO2–P adsorbent from simulated high level liquid waste of PUREX reprocessing

To separate platinum group metals (PGMs) from high level liquid waste (HLLW), a novel silica-based (Crea + TOA)/SiO2–P adsorbent was synthesized by impregnating Crea (N′,N′-di-n-hexyl-thiodiglycolamide) and TOA (trioctylamine) two extractants into the macroporous SiO2–P support with a mean diameter of 60 μm. Adsorption properties and behavior of PGMs from simulated HLLW onto the novel silica-based (Crea + TOA)/SiO2–P adsorbent were investigated by batch method. It was found that (Crea + TOA)/SiO2–P adsorbent exhibited good adsorption selectivity for PGMs over the other tested fission product element in a wide HNO3 concentration. This adsorbent showed strong affinity to Pd(II) but almost no adsorption for rare earth elements. Adsorption process of PGMs could be expressed by Langmuir monomolecular layer adsorption mode and be governed by the chemisorption process. In addition, the adsorption isotherms and thermodynamic parameters of tested elements were calculated by Langmuir equation, Freundlich equation and van’t Hoff equation, respectively.