Design of an adsorbent-bearing silica Schiff base ligand for the highly efficient removal of uranium and thorium in acidic solutions

摘要

This report describes the design and development of functionalized silica particles using tethered Schiff base ligands for uranium extraction from rare earth element leach liquors. We evaluated different grafting approaches (both one- and two-sided tethering); and found the maximum U(VI) adsorption capacity for the functionalized silica was 95 +/- 2 mg g(-1). The functionalized particles demonstrated a very high degree of affinity for the uranyl and thorium ions with K-d values at pH 6 exceeding 19,000 and 900,000 mL g(-1), respectively. This selectivity for these ions is better than most metal ions present in leach liquors, and the extraction kinetics are faster than pure Schiff base crystals. The Schiff-base-functionalized silica particles also exhibited a high degree of reusability over five cycles of loading-elution in the conditions tested.