First Report on a 1-Cycle Solid-Phase Extraction Method for Selective Separation of Am3+ and Eu3+: Use of BTP-Grafted Silica Decorated on Activated Carbon

A new composite sorbent material was prepared by grafting bis-triazinylpyridine (BTP) onto silica and then blending it with activated charcoal (AC–Si–BTP) for the selective separation of Am3+ over Eu3+ using a 1-cycle solid-phase extraction for the direct separation of lanthanides from actinides. BTP was attached to silica via a sulfonamide bond between R–BTP and amino silane, and the resulting Si–BTP was covalently bonded to activated carbon (AC) with a favorable orientation of the ligand coordination sites. The material exhibited a significantly large distribution coefficient for Am3+ over Eu3+ at lower acidities (<0.5 M HNO3), and the separation factor between the two metal ions was found to be maximum in 0.2 M HNO3 with a value of 110. The loading capacity of the material was 4.05 ± 0.12 mg of Eu per gram of the composite when investigated at pH 3. The radiation stability of the material was excellent when studied up to an absorbed dose of 1000 kGy. The material was tested for the separation of Am3+ and Eu3+ in a column mode, which gave selective loading of Am3+ over Eu3+. The reusability studies indicated slow leaching of the BTP fraction from the solid, with a resultant decrease of the Kd values with time. To address this issue, the material was embedded in polysulfone beads for a separate set of studies, but the separation efficiencies were found to be comparable.