TY - JOUR

T1 - Insights into the interaction of iodide and iodine with Cu (II)-loaded bispicolylamine chelating resin and applications for nuclear waste treatment

AU - Robshaw, Thomas

AU - Griffiths, Sion M.

AU - Bezzina, James P.

AU - Waller, Archibald G. L.

AU - Hammond, Deborah B.

AU - van Meurs, Sandra

AU - Ogden, Mark

PY - 2020/6/15

Y1 - 2020/6/15

N2 - Radioiodine is a challenging contaminant to remove from aqueous wastestreams, resulting from spent nuclear fuel reprocessing. To create a selective, economical adsorbent, a Cu-loaded bispicolylamine chelating resin was produced, from commercially available reagents and its performance for removal of aqueous iodide and iodine was assessed. The resin possessed a large equilibrium uptake capacity of 305 ± 14 mg.g−1 iodide and 2940 ± 180 mg.g−1 total iodine. Performance was close to maximal over a pH range of 2–10. Capacity was reduced by ~55% by the addition of cocontaminants nitrate and molybdate, but resistance to suppression was greatly superior to non-modified polyamine resins, clearly seen in dynamic column experiments. The uptake mechanism was investigated spectroscopically and was found to proceed via ligand-exchange, with some in-situ REDOX chemistry occurring, resulting in the formation of Cu(I) and triiodide. The latter was concurrently adsorbed on to the resin and occupied both strong (Cu-associated) and weak (charge-transfer complex formation) binding sites. Thermal decomposition of the loaded resins revealed that the captured iodine was volatised at several different temperatures, according to strength of adsorption, but a large fraction was converted to stable CuI, suggesting a possible pathway towards volume-reduction and immobilisation as a final wasteform.

AB - Radioiodine is a challenging contaminant to remove from aqueous wastestreams, resulting from spent nuclear fuel reprocessing. To create a selective, economical adsorbent, a Cu-loaded bispicolylamine chelating resin was produced, from commercially available reagents and its performance for removal of aqueous iodide and iodine was assessed. The resin possessed a large equilibrium uptake capacity of 305 ± 14 mg.g−1 iodide and 2940 ± 180 mg.g−1 total iodine. Performance was close to maximal over a pH range of 2–10. Capacity was reduced by ~55% by the addition of cocontaminants nitrate and molybdate, but resistance to suppression was greatly superior to non-modified polyamine resins, clearly seen in dynamic column experiments. The uptake mechanism was investigated spectroscopically and was found to proceed via ligand-exchange, with some in-situ REDOX chemistry occurring, resulting in the formation of Cu(I) and triiodide. The latter was concurrently adsorbed on to the resin and occupied both strong (Cu-associated) and weak (charge-transfer complex formation) binding sites. Thermal decomposition of the loaded resins revealed that the captured iodine was volatised at several different temperatures, according to strength of adsorption, but a large fraction was converted to stable CuI, suggesting a possible pathway towards volume-reduction and immobilisation as a final wasteform.

KW - Bispicolylamine

KW - Adsorption

KW - Ion-exchange

KW - Spent nuclear fuel

KW - Radioiodine

KW - Metal-loaded resin

U2 - 10.1016/j.cej.2020.124647

DO - 10.1016/j.cej.2020.124647

M3 - Article

VL - 390

SP - 124647

JO - Chemical Engineering Journal

JF - Chemical Engineering Journal

SN - 1385-8947

ER -