Supercritical fluid extraction of aromatic contaminants from a sandy loam soil

Abstract

Abstract Near‐critical fluids and liquefied gases can achieve high efficiencies in the extraction of organic contaminants from soil. Adsorptive behavior of several polycyclic aromatic hydrocarbons (PAHs) from supercritical carbon dioxide (SC CO 2 ) onto sandy loam‐type soil has been characterized. Data for the solubility of phenanthrene, anthracene, triphenylene, and perylene in SC CO 2 demonstrates a strong relationship between solubility and the carbon number and angularity of the ring structure. Soil adsorption isotherms for these compounds are non‐linear, and have been described using Freundlich and BET adsorption models. The slope of the adsorption isotherms has been correlated with PAH solubility on log‐log coordinates. Addition of polar modifiers, e.g. , water or methanol, dramatically reduces the PAH adsorption levels, indicating the importance of polar adsorption sites on soil surfaces.