Influence of metal ion on sorption of p-nitrophenol onto sediment in the presence of cetylpyridinium chloride

Heavy metals and surfactants have a significant effect on the sorption of organic contaminants. In this study, batch equilibrium experiments were carried out to investigate the influence of Pb(NO3)2 on the sorption of p-nitrophenol (PNP) onto sediments in the presence of cationic surfactant cetylpyridinium chloride (CPC). Results indicated that in the complex system containing PNP, Pb(NO3)2 and CPC, the sorption of PNP decreased with increasing concentration of Pb(NO3)2 due primarily to competing for adsorption sites. Likewise, partitioning of PNP in adsorbed surfactant layers and micelles decreased with increasing level of Pb(NO3)2. Moreover, the influence of different metal ions (Pb2+, Cd2+, Zn2+) was examined and results indicated that the presence of heavy metals inhibited the sorption of PNP in the order: Pb2+ > Cd2+ > Zn2+. The competitive effect of the heavy metals was in agreement with the hydration energy and hydrated radius. The results are believed to provide a useful insight into describing the transport and fate of PNP in natural environments.