Supercritical fluid (SCF) extraction is a promising new technique for the cleanup of soils, sediments, and sludges that are contaminated with hazardous wastes. The ability of SCFs to solubilize heavy molecular weight organics is well-documented. In this investigation, supercritical carbon dioxide (SC-CO2) with a single entrainer, either methanol or toluene, is compared to pure CO2; comparison is made on the basis of extraction rate and efficiency of removal of DDT from contaminated soils. The supercritical mixtures at 100 atm and either 40 or 80 °C were continuously passed through a fixed bed of 10 g of soil. The most effective solvent system, SC-CO2with 5 wt % (6.8 mol %) methanol at 40 °C and a flow rate of 0.7 g/s, was able to leach approximately 95% of the DDT from the soil in under 5 min, as compared to either pure CO2or CO2with 5 wt % (2.5 mol %) toluene at the same conditions, which could only extract 70% in 10 min.
No takes yet. Share an insight, caveat, or question.
Dooley et al. (1987) studied this question.