Interaction of engineered nanoparticles with hydrophobic organic pollutants

As nanomaterials become increasingly part of everyday consumer products, it is imperative to measure the potential release during production, use, and disposal, and assess their impact on human health and the ecosystem. This compels the research to better understand how the properties of engineered nanomaterials (ENM) lead to their accumulation and redistribution in the environment, whether they could become emerging pollutants or if can affect the mobility and bioavailability of other toxins. Organics pollutants that are liquid at room temperature associate with nanoparticles in an aqueous medium not only as molecules adsorbed on nanoparticles surfaces, but also as a discrete phase to form microscopic oil-nanoparticle aggregates. On the basis of our recent studies, pollutant-NP-aggregate formation is believed to be instrumental in an intended or unintended dispersion of organic pollutants. This knowledge would allow the use of environmentally friendly nanoparticles for cleanup of oil spills or other techniques such as surf washing. A better understanding of the nature and properties of pollutant-nanoparticle-aggregate will help predict the fate of pollutants in the aquatic environment. This work describes the various instruments and methods currently available for the detection and identification of pollutant-nanoparticle-aggregate. The sorptive properties of engineered nanomaterials (ENMs) were also investigated, with polyaromatic hydrocarbons and organochlorine pesticides used as model pollutants. Linear Freundlich adsorption constants for the ENMs were correlated with the octanol-water partitioning organic pollutants. The suspended particles from the water phase were separated, and the adsorbed substances were analyzed using a combination of thermal-chromatographic-mass spectroscopic techniques. Sorption of hydrophobic organic pollutants to nano-particles increased the concentration of contaminants in the aqueous phase as compared to the "real" partitioning due to the octanol-water partitioning. The effects water chemistry on the partitioning of hydrophobic pollutants to EMS were investigated. The effects of nano-materials on the mobility of pollutants that are commonly found at many sites have been studied. These compounds include aromatic hydrocarbons, and two and three-ring polyaromatic hydrocarbons that have relatively small water solubility. The high partitioning coefficient indicated engineered nanomaterials have the potential to increase the mobility of hydrophobic pollutants in aquatic environment.