Environmental implications of copper nanohybrids in natural waters

Academic Research Topics in Environmental Measurement and Monitoring
Oral Presentation

Prepared by A. Adeleye1, S. Pokhrel2, L. Mädler2, A. Keller1
1 - University of California Center for Environmental Implications of Nanotechnology, Bren School of Environmental Science & Management, Santa Barbara, California, 93106, United States
2 - Foundation Institute of Materials Science, Department of Production Engineering, University of Bremen, Bremen, , Germany


Contact Information: adeleye.adeyemi@epa.gov; 805-637-2111


ABSTRACT

Widely used engineered nanoparticles are often doped with other elements/compounds to improve their functionality and, at times, stability. However, the environmental implication of these nanohybrids are often not well-understood. In this study, the fate and effects of CuO doped with Fe (0 – 10%) was investigated. The colloidal stability of the Fe-doped CuO nanoparticles in aqueous media, as determined by their critical coagulation concentrations (CCC), decreased with increase in Fe-doping. However, decrease in the overall particle density lead to slower sedimentation of Fe-doped CuO than would have been predicted from their aggregation behavior. Nevertheless, more than 60% of the total nanoparticle/nanohybrid mass initially released into water settled out within 24 h regardless of Fe-doping. Most of the particles (? 50%) that remained suspended in water were larger than 200 nm, but transmission electron microscopy (TEM) analyses showed that these were mainly made up of aggregated nanosized particles, probably held together by van der Waals attraction. In addition, Fe-doping significantly affected CuO dissolution (p < 0.001). In general, Fe-doping promoted the leaching out of Cu ions from the Fe-doped CuO nanoparticles. Despite promoting the release of ionic Cu from the nanohybrids, Fe-doping did not increase the toxicity of CuO nanohybrids to marine phytoplankton, Isochrysis galbana at the concentrations tested (0.05 – 10 mg/L). Reactive oxygen species production in Isochrysis was also insignificant in these toxicity studies, with or without Fe-doping of CuO.