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by mscholz
3131 days ago
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HPLC separates molecules based on some chemical property. In this case, the N@C60 fullerenes are probably very slightly larger, distorted from pure icosahedral symmetry, or have different electronic structure to the plain C60. Chemically speaking, U235 is probably very much like U238 and the chemical compounds of the isotopes are probably chemically almost identical (since isotopic chemical reactivity depends basically on the so-called kinetic isotope effect, which is larger if there is a large difference in mass between isotopes). HPLC is basically a standard synthetic laboratory procedure and has no relevance (that I know of) to uranium separation aside from purifying bulk chemicals. |
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> In standard chromatography, substances having different chemical characteristics are separated by making them run a kind of gauntlet—an obstacle course that blocks the passage of one thing more than the other. HPLC works by using a pumped solvent (hence the term “high pressure”) to strip off the laid-down film of carbon fullerenes in such a way that the desired molecules—the fullerenes encasing nitrogen—are carried away preferentially.
My interpretation of that statement is that HPLC uses a solvent that manages to detach the slightly lighter (and/or less electrostatically-attracted-to-the-film) molecule first, giving it a head start down the diffusion tube, letting the tubes be really short, and thus giving you a tabletop device instead of capital equipment in a dedicated facility.
Maybe HPLC of N@C60 really leans on that differential-electrostatic-attraction property, but it seems like the process would still work to separate isotopes that differ only by molecular weight.
I'm not a chemist of any sort, though, so I'd be glad to "get schooled" here.