Supercritical fluid extraction of polycyclic aromatic hydrocarbon mixtures from contaminated soils

Journal Article · Sun Feb 01 04:00:00 EST 1998 · Industrial and Engineering Chemistry Research

DOI:https://doi.org/10.1021/ie9704105· OSTI ID:605712

Becnel, J M; Dooley, K M ^[1]

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1. Louisiana State Univ., Baton Rouge, LA (United States). Dept. of Chemical Engineering

Highly contaminated (with PAHs) topsoils were extracted with supercritical CO{sub 2} to determine the feasibility and mechanism of supercritical fluid extraction (SFE). Effects of supercritical fluid (SCF) density, temperature, and cosolvent type and amount and of slurrying the soil with water were investigated. Experiments were conducted at 308--343 K and 450--850 kg/m{sup 3} CO{sub 2} density. Water and methanol were used as cosolvents in some experiments, at 0.3--6 wt %. For extractions at an {approximately} 1,000 phase ratio (wt of CO{sub 2}/wt of soil), near-complete contaminant removal was achieved. For an {approximately} 200 phase ratio at 323 K and 13.8 MPa, > 95% of two-ring PAHs and > 80% of three-ring and heavier PAHs were extracted. Using soil slurries with water had little effect on the total recoveries. Changes in SCF density also had little influence on SFE, while temperature increases improved both initial rates of extraction and total recoveries. Addition of cosolvents generally hindered extraction of the contaminants. These results are used to show that, at typical conditions for CO{sub 2}-based soil extractions, the solubility of the contaminant in the SCF does not limit SFE. Other internal resistances are important, such as desorption from and diffusion within the polymeric soil organic matter.

• OSTI ID: 605712
• Journal Information: Industrial and Engineering Chemistry Research, Journal Name: Industrial and Engineering Chemistry Research Journal Issue: 2 Vol. 37; ISSN IECRED; ISSN 0888-5885
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
CARBON DIOXIDE
PARAMETRIC ANALYSIS
POLYCYCLIC AROMATIC HYDROCARBONS
REMEDIAL ACTION
SOILS
SUPERCRITICAL GAS EXTRACTION