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What procedures would be available to remove SF6 from a sample (or stream) of gas?

The ideal answer would be a list of options. If it helps, please assume the rest of the sample consists of noble gases, although something that would work in presence of other impurities would be even better.

Specific example sample if it helps:

  • Impurities: 0.1% water vapour. Otherwise Ar 30%, Kr 39.8%, Xe 30%.
  • Volume: 300 mL.
  • Effectiveness: at least 80% after one or more passes.
  • Concentration of SF6 in initial sample: 0.1%.
Cedric Knight
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    Multiple stages of ultra-centrifugation? – Ed V Aug 13 '22 at 18:07
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    How much SF6 in the stream? Really hard in general… – Jon Custer Aug 13 '22 at 18:28
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    SF6 is very non-polar, and it must soluble in a lot of solvents (basically scrubbing process)...check in these directions as well, or what about condensation? – AChem Aug 13 '22 at 18:58
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    If you want to focus on SF6, you could have edited your previous question and include only SF6. In this way, your question could have been reopened. – Nilay Ghosh Aug 14 '22 at 06:40
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    You're asking much too general for any sensible answer. What other impurities?! You can obviously freeze it at -80dC. If that's not what you want, you should say so. And what concentration does it have? How effective do you want your removal? – Karl Aug 14 '22 at 17:56
  • Is this related to your other question about removing fluorinated stuff from the atmosphere? If so, on what order of magnitude do you want to operate? – Karl Aug 14 '22 at 17:59
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    Please consider this an independent question (the consensus seems to be it would have little bearing on the other). Magnitude: say 330 mL. Effectiveness: anything over 80%. Concentration: I wanted to leave that open, but say 0.1%. I couldn't resist some complicating factors, but the simple case is just with argon, krypton and xenon, as already obtained from distillation, The ideal answer would be a list of options. Will add this. – Cedric Knight Aug 14 '22 at 20:16
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    Apparently, sulfur hexafluoride reacts exothermically with solid lithium. So dry the gas mixture you posit and run it through the lithium. Of course, if nitrogen were present, then this would not be feasible. – Ed V Aug 14 '22 at 21:26

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Per a source: "Efficient Removal of Sulfur Hexafluoride (SF6) Through Reacting with Recycled Electroplating Sludge" by Jia Zhang. A link to abstract, and quoting:

This paper reports that recycled electroplating sludge is able to efficiently remove greenhouse gas sulfur hexafluoride (SF6). The removal process involves various reactions of SF6 with the recycled sludge. Remarkably, the sludge completely removed SF6 at a capacity of 1.10 mmol/g (SF6/sludge) at 600 °C. More importantly, the evolved gases were SO2, SiF4, and a limited amount of HF, with no toxic SOF4, SO2F2, or SF4 being detected. These generated gases can be readily captured and removed by NaOH solution. The reacted solids were further found to be various metal fluorides, thus revealing that SF6 removal takes place by reacting with various metal oxides and silicate in the sludge. Moreover, the kinetic investigation revealed that the SF6 reaction with the sludge is a first-order chemically controlled process. This research thus demonstrates that the waste electroplating sludge can be potentially used as an effective removal agent for one of the notorious greenhouse gases, SF6.

Hope this helps.

AJKOER
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