Equilibrium Batch Experiments with Six Polycyclic Aromatic Hydrocarbons and Two Aquifer Materials

Abstract

Batch experiments were carried out to investigate the adsorption of six polycyclic aromatic hydrocarbons (PAH) (naphthalene, fluorene, phenanthrene, anthracene, fluoranthene, and pyrene) by two aquifer materials. The results show that the adsorption of these PAH is adequately described by the linear isotherm model. Adsorption of naphthalene or fluorene in a mixture with other PAH was suppressed slightly compared to measurements when only one compound was in solution. Regression equations relating the slope of the linear isotherm (kd) to the coefficient of partition between octanol and water (Kow) of the compounds and the fraction of organic carbon (foc) of the material predicted the order of adsorption of the six PAH, but the predicted and measured values of Kd differ by a factor of up to four. Predictions based on the solubility of the PAH gave larger differences from the measured results and did not agree with the measured order of adsorption of these compounds. The adsorption and desorption of fluorene were found to be hysteretic.