Effects of metallic cations on desorption of polycyclic aromatic hydrocarbons from long-term contaminated soil

Effects of ion strength and ion types on desorption of polycyclic aromatic hydrocarbons(PAHs) were examined.Based on Pearson principle,the basic characteristics of phenanthrene(PHE),fluoranthene(FLU),pyrene(PYR) and benzo[k]fluoranthene(B[k]Fl) were calculated to determine their acidic-basic types.The experimental results indicated that ion strength was not the key controlling factor on PAHs desorption.The acidic-basic interaction between metallic ions with different hardness and PAHs was the key influencing point on the PAHs desorption level variation from the contaminated soil.Hard acidic metallic cations,such as Ba2+,Al3+ and Ca2+,can expedite PAHs desorption.In contrast,acidic cations,such as Hg2+ and Ag+,played an inhibition role.The borderline acidic cations,such as Cu2+,Fe2+ and Zn2+,can enhance PAHs desorption more significantly.