Adsorption Behavior of Platinum Group Metals onto a Silica-based (Crea+Dodec)/SiO₂-P Extraction Resin from Simulated High Level Liquid Waste

Abstract

Basic properties of a silica-based macroporous N’,N’-di-n-hexyl-thiodiglycolamide (Crea) extraction resin, (Crea+Dodec)/SiO₂-P were examined. This extraction resin was synthesized by impregnating Crea and its modifier, n-Dodecyl alcohol (Dodec) into the macroporous SiO₂-P support with a mean diameter of 50 μm. Adsorption behavior of platinum group metals (PGMs) and some fission product elements from simulated high level liquid waste onto the resin was investigated by batch experiment. It was found that (Crea+Dodec)/SiO₂-P extraction resin exhibited good adsorption selectivity for PGMs over other tested elements in 0.1-5.0 M HNO₃ solution. This resin showed strong affinity to Pd(II) especially in a short contact time but almost no adsorption for rare earth elements. Adsorption behavior of PGMs in experiment could be expressed by the Langmuir monomolecular layer adsorption mode. Meanwhile, adsorption results were fitted well with the pseudo-second order model and the rate-controlling step of this adsorption process was governed by the chemisorption process. In addition, the adsorption isotherms and thermodynamic parameters of tested elements were calculated by the Langmuir, Freundlich, and van’t Hoff equations, respectively.

Keywords:

• platinum group metals
• (Crea+Dodec)/SiO₂-P extraction resin
• extraction chromatography
• high level liquid waste