Supercritical carbon dioxide extraction of polycyclic aromatic hydrocarbons from contaminated soil

Thesis/Dissertation · Mon Jan 01 04:00:00 EST 1990

OSTI ID:7014892

Andrews, A T

Supercritical fluids (SCFs) can achieve high efficiencies in the extraction of organic contaminants from soil due the unique properties of a fluid in the vicinity of its critical point. However, the adsorptive interactions between a complex matrix such as soil, nonpolar organic species, and nonpolar SCFs are not well understood. The adsorptive behavior of several polycyclic aromatic hydrocarbons (PAHs) from supercritical carbon dioxide (SC CO[sub 2]) onto a sandy loam soil was characterized. Solubility and adsorption measurements were carried out in a novel apparatus which incorporated on-line sampling of high-pressure SC CO[sub 2] circulating through a fixed bed extractor. Data for solubility of phenanthrene, anthracene, triphenylene, chrysene and perylene in SC CO[sub 2] at temperatures ranging from 25 to 70C and fluid densities of 0.7 to 0.9 g/mL demonstrates a relationship between solubility and carbon number/angularity of the ring structure. PAH solubility follows a van't Hoff type functionality, with heats of solution, [Delta]H[sub sol], obtained from linear plots of ln [solubility] versus 1/T. Magnitudes of [Delta]H[sub sol], comprised of additive contributions of fusion and dilution, ranged from 9 to 11 kcal/mole, consistent with weak van der Waals solute/solvent interactions. Solubilities are enhanced by addition of a polar modifier. A solubility model, based on Scatchard-Hildebrand Regular Solution Theory, was developed to describe the P-T behavior of PAH solubility. Soil adsorption isotherms for these compounds are non-linear, and were described using Freundlich and Brunauer-Emmett-Teller adsorption models.

• Research Organization: Rutgers--the State Univ., New Brunswick, NJ (United States)
• OSTI ID: 7014892
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540220* -- Environment
Terrestrial-- Chemicals Monitoring & Transport-- (1990-)
ADSORPTION
AROMATICS
CLEANING
DECONTAMINATION
EXTRACTION
HYDROCARBONS
MANAGEMENT
MATERIALS RECOVERY
ORGANIC COMPOUNDS
POLYCYCLIC AROMATIC HYDROCARBONS
PROCESSING
REMEDIAL ACTION
SEPARATION PROCESSES
SOILS
SOLUBILITY
SORPTION
WASTE MANAGEMENT
WASTE PROCESSING