Removal of polycyclic aromatic hydrocarbons from contaminated soil by aqueous DNA solution

An aqueous DNA solution was applied for the extraction of polycyclic aromatic hydrocarbons (PAHs) from a spiked soil. Solubilities of 0.56, 11.78, and 11.24 mg L(-1) for anthracene, phenanthrene, and pyrene, respectively, were achieved after 1 day equilibration in 1% DNA. Using a spiked soil that contained 72 mg kg(-1) anthracene, 102 mg kg(-1) phenanthrene, and 99 mg kg(-1) pyrene, extractions of close to 88, 78, and 94%, respectively, were attained with 5% DNA at a 1:50 soil/extractant ratio. Maximum PAH dissolution occurred after 4-6 h. Comparative tests showed the main advantage of DNA over methyl-beta- and gamma-cyclodextrins and Tween 80 for pyrene removal. An ionic strength of 0.1 M NaCl was found necessary for maximum PAH dissolution and extraction. The performance of hexane regenerated DNA also remained stable after three stages of recycling. These results show the huge potential of DNA as an aqueous washing agent for PAH-contaminated soil.