On the Adsorption Kinetics and Equilibrium of Polyaromatic Hydrocarbonsfrom Aqueous Solutions

摘要

The purpose of the present work was to explore the removal of threepolycyclic aromatic hydrocarbons (naphthalene, fluorene and acenaphtene) (PAHs)from aqueous solution onto an activated carbon. The adsorption performance of thesecompounds (both kinetic and equilibrium) has been discussed in terms of theirchemical and physical properties. The results showed that the rate of adsorption wasstrongly dependent on the molecular size of the hydrocarbons. Thus, for example,steric hindrances associated with acenaphthene inhibited the accessibility of thiscompound to the high-energy sites. Under equilibrium conditions, the uptake seemedto be govemed by the carbon—PAH affinity, as the lowest uptake was obtained fornaphthalene which displayed the fastest adsorption rate. The interactions between thestudied pollutants and the activated carbon seemed to be controlled by two factors,viz. aromaticity and water solubility. As a general rule, the higher the number ofaromatic rings in the polycyclic hydrocarbon, the more favoured theadsorbate—carbon interactions. Analysis of the carbon after adsorption of the studied.hydrocarbons indicated that the accessibility restrictions to the porosity of the carboncan also lead to weaker interactions with the activated carbon.