Supercritical fluid and Soxhlet extractions of organics from sediments
- Pacific Northwest Lab., Richland, WA (United States)
The authors evaluated solvent consumption, atmospheric emissions, and waste generation as factors contributing to environmental, safety, and health issues associated with the extraction of organic materials from sediments when commercially available supercritical fluid extraction (SFE) and Soxhlet extraction systems are used. They found that the Soxhlet system used 10 times as much solvent as the SFE system and released about 6 times the volume of solvent into the atmosphere. Although the total volume of solvent released was much greater for Soxhlet than for SFE extractions, the mean concentration of solvent in the exhaust air from operation of SFE was about 10 times higher because the SFE extraction was much quicker (40 min vs. 18--24 h). As a consequence, operation of Soxhlet or SFE systems under conditions that do not control vapor releases could lead to air concentrations that exceed threshold limit values (TLVs) provided as guidelines for industrial exposure. The releases at facility stacks could also exceed the ambient air concentration limits for hazardous chemicals. Soxhlet systems produced significant liquid waste and some solid hazardous waste. Although components of the SFE process did not produce any liquid waster, they did produce solid waste that may be hazardous unless the solvent modifiers are carefully selected and their concentrations controlled in the supercritical fluid.
- DOE Contract Number:
- AC06-76RL01830
- OSTI ID:
- 136712
- Journal Information:
- Chemical Health amp Safety, Journal Name: Chemical Health amp Safety Journal Issue: 5 Vol. 2; ISSN 1074-9098; ISSN CHLSEG
- Country of Publication:
- United States
- Language:
- English
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