Extraction of phenanthrene and fluoranthene from contaminated sand using palm kernel and soybean oils

Experimental extraction tests are conducted to investigate feasibility of saturated palm kernel oil (PKO) and unsaturated soybean oil (SO) to extract polycyclic aromatic hydrocarbons (PAHs) from contaminated sand. The extraction rates and efficiencies for lowly contaminated (LC) and highly contaminated (HC) sands at temperatures of 30 °C and 70 °C are evaluated using empirical first order kinetic dissolution models. In LC sand, the extraction is dominated by the diffusion of PAHs adsorbed onto particle surfaces and the direct dissolution of PAH phase. In HC sand, a rapid diffusion of PAHs adsorbed onto particle surfaces and a direct dissolution of PAH phase occur followed by a slower diffusion of PAHs entrapped within the pores and micropores. Larger diffusion resistance during HC sand extractions results in an average 10.8% reduction in extraction efficiencies compared to LC sand. Increased temperature generally increases the mass transfer rates and extraction efficiencies. Additionally, the physicochemical properties of both oils and PAHs also determine the extent of PAH extraction into oil.

► Diffusion of PAHs from surfaces occurs in extraction from lowly contaminated sand.
► For highly contaminated sand, PAH extraction occurs via biphasic diffusion.
► PAH extraction efficiencies decrease in highly contaminated sand extractions.
► Higher temperature increases PAH mass transfer rates and extraction efficiencies.
► Differences in properties of oils and PAHs affect the extraction efficiencies.