Environment, health and safety

Which abatement method is appropriate for removing extremely stable, hard-to-decompose PFCs such as CF4 from tool exhaust?

  1. AA wet scrubber that only washes with water
  2. BAdsorption on activated carbon alone
  3. CMethods that decompose them at high temperature, such as combustion or plasma
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Answer: C. Methods that decompose them at high temperature, such as combustion or plasma

PFCs such as CF4 are chemically very stable and barely dissolve in water, so wet scrubbers and ordinary adsorption remove almost none of them. They are decomposed at high temperatures of around 1000 °C or more by combustion, electric heaters, plasma and the like, and the resulting hydrogen fluoride and other products are removed by a downstream wet scrubber.

  • A. PFCs barely dissolve in water, so washing with water alone cannot remove them.
  • B. Stable PFCs cannot be removed sufficiently by adsorption alone.
  • C. Correct. They are decomposed at high temperature and the products treated downstream.
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