Adsorption of PAHs on the Sediments from the Yellow River Delta as a Function of Particle Size and Salinity

In a seawater environment, the particle size of sediment and salinity play an important role in the adsorption behaviors of polycyclic aromatic hydrocarbons (PAHs) on sediment. In this study, batch adsorption experiments were carried out with the sediments from the Yellow River Delta (YRD) to explore the effect of particle size and salinity on the adsorption behaviors of phenanthrene (Phe), fluoranthene (Fla), and pyrene (Pyr). Adsorption isotherms of PAHs on different-sized sediments can be described by a Freundlich model with the correlation coefficients ranging from 0.96 to 0.99. The adsorption capacity of PAHs was in reverse proportion to the particle size of the sediments and in direct proportion to salinity. The sediments with smaller particle size possessed higher content of aromatic and fat components, which had strong adsorption capacity toward PAHs. Salinity influenced the adsorption behaviors of PAHs by changing the solubility of PAHs and the physicochemical properties of the sediments. The salting-out constants of Phe, Fla, and Pyr were in the range of 0.292 to 0.296, 0.230 to 0.289, and 0.293 to 0.307 l/mol, respectively. These research findings are of importance to an assessment of the fate and transport of PAHs in seawater-sediment systems.