Soil cleaning by carbon dioxide extraction: A review

Supercritical carbon dioxide is a solvent for non‐polar solids and volatile compounds. It dissolves hydrocarbons, polyaromatic hydrocarbons (PAH's), chlorinated hydrocarbons (such as PCB's and dioxins), phenols, chlorinated phenols and many pesticides and herbicides. Supercritical carbon dioxide effectively extracts the non‐polar compounds from all soil types. The extraction of more polar compounds, such as chlorophenols and some pesticides requires that a polar compound, such as a short chain alcohol is added to the carbon dioxide. Carbon dioxide extraction is usually quicker and in cases more complete than the standard analytical methods which use organic liquid solvents as extraction medium. Supercritical carbon dioxide extraction is used by environmental analysis laboratories as a more efficient, occupationally more acceptable method for analyzing contaminated soils. Plans to construct transportable units for large scale soil cleaning have been published.