Treatment of spent electropolishing solution for removal of cobalt-60
The Irradiated Materials Examination and Testing (IMET) Facility at Oak Ridge National Laboratory electropolishes various types of irradiated metal specimens prior to examination of metallurgical and mechanical properties. The standard electropolishing solution used at IMET for most specimens consists of a 7:1 methanol/sulfuric acid mixture, with smaller amounts of a 3:1 methanol/nitric acid solution and a 10:6:1 methanol/2-butoxyethanol/perchloric acid solution also being used. Cobalt-60 is the primary source of gamma radiation in the spent solutions, with lesser amounts from manganese-54 and iron-59. A treatment method is needed to remove most of the Co-60 from these solutions to allow the waste solutions to be contact-handled for disposal. A wide range of adsorbents was tested for removing cobalt from the electropolishing solutions. No adsorbent was found that would treat full strength solution, but a complexing ion exchange resin (Chelex 100, BioRad Labs, or Amberlite IRC-718, Rohm and Haas Co.) will remove cobalt and other heavy metals from partially neutralized (pH=3) solution. A 5 wt% sodium hydroxide solution is used for pH adjustment, since more concentrated caustic caused sodium sulfate precipitates to form. Lab-scale column tests have shown that about 10 bed volumes of methanol/sulfuric acid solution, 30 bed volumes of methanol/nitric acid solution or 15 bed volumes of methanol/2-butoxyethanol/perchloric acid solution can be treated prior to initial Co-60 breakthrough.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC05-96OR22464
- OSTI ID:
- 211395
- Report Number(s):
- CONF-960271-5; ON: DE96006725; TRN: 96:009361
- Resource Relation:
- Conference: American Institute of Chemical Engineers (AIChE) spring meeting, New Orleans, LA (United States), 26-29 Feb 1996; Other Information: PBD: Feb 1996
- Country of Publication:
- United States
- Language:
- English
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