Stable containment of radionuclides on the nanoscale by cut single-wall carbon nanotubes

The physisorption of radiolabeled (125)I(-) ions from aqueous solution and the Brunauer-Emmett-Teller (BET) surface areas of various carbonaceous materials [HiPco single-wall carbon nanotubes (SWNTs), F-SWNTs, cut SWNTs, charcoal, graphite, F-graphite and C(60)] have been measured and compared. By far, cut SWNTs (mainly 20-50 nm lengths) displayed the largest surface area of the materials (1180 m(2).g(-1)), being approximately double that of uncut SWNT and charcoal. At low concentrations of (125)I(-), nearly all of the (125)I(-) was adsorbed from aqueous solution within 1 min at room temperature by the cut SWNTs, uncut SWNTs, and charcoal; the other materials showed much less adsorption under the same conditions. Once adsorbed, the (125)I(-) wash-off rate by pure water was highly variable but was especially slow for cut SWNTs (t(1/2) approximately 2720 h) compared to the other materials; wash-off of (125)I(-) by an aqueous H(2)O(2) solution was even slower (t(1/2) approximately 14 300 h). Taken together, these data demonstrate the greatly increased surface area and dramatically enhanced retention properties of cut SWNTs over uncut SWNTs.