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Environmental Factors And Surface Properties Of Nanoparticles Governing Their Fate, Reactivity, And Mobility
Citation:
SCHECKEL, K. G., S. R. AL-ABED, T. P. LUXTON, T. M. TOLAYMAT, H. Choi, A. M. El Badawy, S. Joo, K. Loftspring, AND G. Silva. Environmental Factors And Surface Properties Of Nanoparticles Governing Their Fate, Reactivity, And Mobility. Presented at 10th International Conference on the Biogeochemistry of Trace Elements, Chihuahua, MEXICO, July 13 - 18, 2009.
Impact/Purpose:
To provide an array of topics concerning the basic principles of nanoparticles with some examples of environmental interaction nanoparticles.
Description:
The application of nanoparticles (NPs) for industrial processes and consumer products is rising at an exponential rate. While NPs are leading to new discoveries and improvements in our daily lives, little consideration is put forth to understand the impact of NPs in the environment. Effort has been put forth to protect manufacturing workers and to produce nanoparticles via green processes (cradle-to-gate), but once the NP product is placed in the commercial market there is little knowledge on the gate-to-grave aspects that may impact human health and the natural environment. The environmental impact of nanoparticles provides many unanswered questions related to fate, reactivity, and mobility. Not only does one need to consider the environmental conditions in which the NPs will reside once in a natural system, but also the unique surface properties of the NPs. The USEPA is actively pursuing research on the potential negative and positive influences of NPs in the environment. Our research has explored environmental conditions and capping agents that direct the surface properties of NPs. Additionally, experiments to examine the fate of nanoparticles as a function of aging time shows that some forms of NPs are not stable in the environment. Lastly, the use of NPs for remediation is being explored for the reductive dechlorination of organic contaminants. Factors such as pH, ionic strength, and valence of counterions in solution with NPs have significant influence on the surface charge and particle size. Further, the capping agents of synthesized NPs are susceptible to influences of solution properties. Once NPs enter the environment, toxicological studies are conducted assuming that the nanoparticle will remain in its manufactured form. Thermodynamics dictate that the environmental conditions in which the NPs interact in a natural system will reduce the nanoparticle to its lowest energy state. Experiments to evaluate the long-term speciation of ZnO and Ag nanoparticles were conducted in simple batch reactors coupled with X-ray absorption spectroscopy (XAS) to identify speciation. Commercial ZnO NPs quickly converted to zinc hydroxide-like and sorbed Zn species within a manner of hours. Silver NPs in a chlorine-free environment remained as Ag NPs; however, in chlorine containing experiment, the presence of AgCl was confirmed. Polychlorinated Biphenyls (PCBs) are a risk management challenge due to their persistency and prevalence in the environment. Utilizing an innovative bimetallic Pd/Fe-impregnated granular activated carbon (GAC) for the simultaneous adsorption and dechlorination of PCBs, USEPA researchers are developing effective remediation methods to deal with contaminated sediments. Manufactured nanoparticles in the environment can be a real concern if a basic knowledge of their fate, reactivity, and mobility is not understood. Further, the right experiments must be done. Focus solely on pure reaction systems will address some concerns, but environmental scientists need to explore the complexity of NPs under environmental conditions where mineral surfaces and organic matter will surely add difficulty to the research. This presentation will provide an array of topics concerning the basic principles of nanoparticles with some examples of environmental interaction nanoparticles.
URLs/Downloads:
FOR FURTHER INFORMATION_PRINCIPAL INVESTIGATOR.PDF (PDF, NA pp, 5 KB, about PDF)Environmental Factors And Surface Properties Of Nanoparticles Governing Their Fate, Reactivity, And Mobility (PDF, NA pp, 10 KB, about PDF)