2. Solvent extraction
In solvent extraction technology, PAHs are removed from soil
using an individual solvent or mixtures of solvents. The two steps
involved in the extraction of a compound from a solid matrix are
desorption from the binding site in (or on) the solid matrix followed
by elution from the solid into the extraction fluid [11].
Typically, mixtures of water and co-solvents or surfactants are used
to extract or wash PAHs from contaminated soil. Advancements
within this field include using non-toxic and biodegradable extraction
agents such as cyclodextrins and vegetable oil as well as using
supercritical and subcritical fluids. Table 3 summarises pertinent
references on the use of solvent extraction for the remediation of
PAH-contaminated soils.
2.1. Soil washing with water and organic solvents
Water and various solvents as well as mixtures of solvents have
been tested at laboratory scale using a rotating shaker to remove 19
PAHsfrom highly contaminated soil by Khodadoust et al. [12]. Using
a soil:solvent extraction ratio of 1 g:100 ml and extraction time of
24 h resulted in similar removal efficiencies of PAHs for ethanol,
2-propanol, acetone and 1-pentanol. Ternary mixtures of water, 1-
pentanol, and either ethanol or 2-propanol were also tested with a