A STUDY OF INTERACTIONS BETWEEN SOIL FRACTIONS AND PAH COMPOUNDS IN THERMAL-DESORPTION OF CONTAMINATED SOILS

The interactions between three polynuclear aromatic hydrocarbons (PAHs ), namely fluorene, naphthalene and anthracene, and three fractions of a soil, namely fulvic acid (FA), humic acid (HA) and humin/inorganic fractions, were studied experimentally. Prepared PAH + soil fraction b inary mixtures, with PAH concentrations ranging over 0.8-7 mass%, were tested using a differential scanning calorimeter (DSC) over a tempera ture range of 20-390 degrees C. The DSC thermograms for the PAH + HA m ixtures showed distinctly different characteristics compared to mixtur es with the other two soil fractions, where the endothermic peak for t he vaporization of the PAH was absent. With the aid of vapour-liquid f lash calculations, the lack of the boiling point peak is interpreted t o be due to the liquid-phase miscibility of the PAHs and the HA fracti on. Implications of the DSC results on the design and performance of t he thermal desorption process are discussed.