The influence of natural organic matter (NOM) on the desorption kinetics of pyrene and naphthalene from quartz

The influence of natural organic matter (NOM) on the desorption kinetics of pyrene and naphthalene adsorbed on quartz was examined in batch experiment s. Online determination of the concentration of the polycyclic aromatic hyd rocarbons (PAH) in the aqueous phase was performed using fluorescence detec tion. Desorption experiments were done in a Completely Mixed Batch Reactor (CMBR) using PAH loaded quartz as model soil. A diluted pyrophosphate extra ct and a water extract of a well characterized soil, water of a bog lake (H ohlohsee, Black Forest), and deionized water were used as aqueous phases. T he experimental data were fitted to two mathematical models: (1) an empiric al model and (2) the diffusion film model. Both models were able to describ e the concentration profile of the dissolved PAH quite well. Whereas the de sorption rate of naphthalene decreased in the presence of NOM, no significa nt influence of NOM on the desorption kinetics of pyrene was observed. In t his context, neither the origin nor the concentration of the different NOM had a significant impact on the values obtained. (C) 1999 Elsevier Science Ltd. All rights reserved.