Development of novel bifunctional anion exchange resins with improved selectivity for pertechnetate sorption from contaminated groundwater

The present study evaluated a new class of bifunctional anion-exchange resi ns with improved selectivity and sorption kinetics for removing pertechneta te (TcO4-) from contaminated groundwater. Both laboratory-column and field flow-through experiments were performed, and results indicated that superio r performance of the bifunctional resins has been achieved through the use of two quaternary ammonium groups,;one having long chains (trihexylamine) f or higher selectivity for poorly hydrated large anions and one having short er chains (triethylamine) for enhanced kinetics and exchange capacity. Fiel d results indicated that the bifunctional resin performed similar to 5 time s better than one of the best commercial monofunctional anion-exchange resi ns (e.g., Purolite A-520E) with respect to the removal of TcO4- from contam inated groundwater, Less than 3% of TcO4- breakthrough was observed after s imilar to 700 000 bed volumes (BV) of contaminated groundwater had been tre ated by the bifunctional resin column (at a flow rate of similar to 6 BV/mi n) at the U.S. Department of Energy's Paducah Gaseous Diffusion Plant site. The results also demonstrate that the new resin is particularly effective in removing low revels of TcO4- (e.g., at nmol/L range), and a cost saving may be realized by using the bifunctional resins for the treatment of large quantities of contaminated groundwater because of its increased selectivit y, treatment efficiency, and longevity. The new resin may also be applied f or the efficient treatment of other poorly hydrated large anions such as pe rchlorate (ClO4-) from contaminated groundwater or surface water.