Grantee Research Project Results
Final Report: Fate and Transformation of C60 Nanoparticles in Water Treatment Processes
EPA Grant Number: R832526Title: Fate and Transformation of C60 Nanoparticles in Water Treatment Processes
Investigators: Kim, Jae Hyung , Hughes, Joseph
Institution: Georgia Institute of Technology
EPA Project Officer: Packard, Benjamin H
Project Period: September 1, 2005 through December 31, 2008
Project Amount: $375,000
RFA: Exploratory Research: Nanotechnology Research Grants Investigating Environmental and Human Health Effects of Manufactured Nanomaterials: A Joint Research Solicitation - EPA, NSF, NIOSH (2005) RFA Text | Recipients Lists
Research Category: Human Health , Safer Chemicals , Nanotechnology
Objective:
The environmental impact of carbon fullerenes is of great concern due to projections for bulk production in near future and the recent discovery that they form nano-scale water-stable aggregates upon release to water. Understanding the fate and the transformations of carbon fullerenes during water treatment, currently our first line of defense against ingestion pathways, is of particular importance. Human exposure to these materials via water ingestion will be strongly influenced by the behavior of these aggregates in potable water treatment systems. The objectives of the proposed research are to examine the fate of fullerenes in various physico-chemical processes in both natural and engineered environments. More specifically, the proposed project examined 1) the fate of model carbon nanometarials, carbon nanotube as a representative model compound, in natural waters, with special focus on elucidating the interaction with natural organic matter, 2) removal and transformation of model carbon nanomaterials by conventional water treatment proceses, 3) photochemical response of C60 as it is related to observed toxicological effects.
Summary/Accomplishments (Outputs/Outcomes):
The research discovered that multi-walled carbon nanotubes (MWNTs) were readily dispersed as an aqueous suspension in both model NOM (Suwannee River NOM (SR-NOM)) solutions and natural surface water (actual Suwannee River water with unaltered NOM background) which remained stable for over one month. These findings suggest that dispersal of carbon based nano-materials in the natural, aqueous environment might occur to unexpected extent following a mechanism that has not been previously considered in environmental fate and transport studies. Experiments performed with various NOM samples suggested that the degree of NOM adsorption varied greatly depending on the type of NOM and was proportional to the aromatic carbon content of NOM. The adsorption of NOM to MWNT was also dependent on water quality parameters: adsorption increased as pH decreased and ionic strength increased.
A series of studies were formed to assess the fate and transformation of C60 clusters during water treatment processes. Experiments performed with jar tests suggested that C60 colloidal aggregates were adequately removed by a series of alum coagulation, flocculation, sedimentation and filtration processes, while the efficiency of removal greatly depended on water quality parameters and coagulant dosage. Transformation of C60 by dissolved ozone and short-wavelength UV irradiation, common disinfection reagents was also studied. Reaction products were characterized by a battery of spectral analyses including NMR, XPS, ATR-IR, UV-Vis, MS-TOF (LDI) and determined to be a highly oxidized fullerenes. Further studies on ozone treated C60 suggested that oxidative transformation of C60 can lead to increased toxicity in addition to increased water solubility and reduced size.
Studies on photochemical reactivity of C60 demonstrated that, althought photoexicted C60 in the aqueous phase efficiently mediated transfer of absorbed energy to oxygen and produced singlet oxygen when associated with surfactant or polymer, when C60 was present as colloidal aggregate suspension, prepared through solvent exchange or sonication, this intrinsic character was lost. Similarly, C60 associated with surfactant mediated electron transfer from electron donor to oxygen producing superoxide radical, while C60 aggregates and C60 associated with polymer did not. These results suggest that the ability of C60 to mediate energy and electron transfer is affected by the degree of C60 aggregation in the aqueous phase as well as characteristics of associated stabilizing molecules. It was also found that THF peroxide forms during the preparation of aqueous stable C60 aggregates which strongly affects the reactivity of C60 in the aqueous phase.
Conclusions:
Conclusions from this multi-faceted reseaech include: 1) dispersal of carbon based nano-materials in the natural, aqueous environment might occur to unexpected extent following a mechanism that has not been previously considered in environmental fate and transport studies; 2) C60 colloidal aggregates are adequately removed by a series of alum coagulation, flocculation, sedimentation and filtration processes, while the efficiency of removal greatly depend on water quality parameters and coagulant dosage; 3) the photochemical reactivity of C60 in the aqueous phase, which has been linked to oxidative damage in biological systems in earlier studies, is strongly dependent on the media environment surrounding C60; 4) accurate assessment of C60 in environmental life cycles and impact should consider the transformation of C60 in the aqueous phase due to oxidation processes (e.g., ozonation and UV irradiation); oxidative transformation of C60 can lead to increased toxicity in addition to increased water solubility and reduced size; 5) formation of THF peroxide during the preparation of aqueous stable C60 aggregates provides another potential explanation for the reactivity and oxidative stress mechanisms of THF/nC60 system reported in the literature.
Journal Articles on this Report : 10 Displayed | Download in RIS Format
Other project views: | All 20 publications | 10 publications in selected types | All 10 journal articles |
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Cho M, Fortner JD, Hughes JB, Kim JH. Escherichia coli inactivation by water-soluble, ozonated C60 derivative:kinetics and mechanisms. Environmental Science & Technology 2009;43(19):7410-7415. |
R832526 (Final) |
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Fortner JD, Kim DI, Boyd AM, Falkner JC, Moran S, Colvin VL, Hughes JB, Kim J-H. Reaction of water stable C60 aggregates with ozone. Environmental Science & Technology 2007;41(21):7497-7502. |
R832526 (2007) R832526 (Final) |
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Hyung H, Fortner JD, Hughes JB, Kim J-H. Natural organic matter stabilizes carbon nanotubes in the aqueous phase. Environmental Science & Technology 2007;41(1):179-184. |
R832526 (2006) R832526 (2007) R832526 (Final) |
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Hyung H, Kim J-H. Natural organic matter (NOM) adsorption to multi-walled carbon nanotubes: effect of NOM characteristics and water quality parameters. Environmental Science & Technology 2008;42(12):4416-4421. |
R832526 (Final) |
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Hyung H, Kim J-H. Dispersion of C60 in natural water and removal by conventional drinking water treatment processes. Water Research 2009;43(9):2463-2470. |
R832526 (Final) |
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Lee J, Fortner JD, Hughes JB, Kim J-H. Photochemical production of reactive oxygen species by C60 in the aqueous phase during UV irradiation. Environmental Science & Technology 2007;41(7):2529-2535. |
R832526 (2007) R832526 (Final) |
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Lee J, Kim J-H. Effect of encapsulating agents on dispersion status and photochemical reactivity of C60 in the aqueous phase. Environmental Science & Technology 2008;42(5):1552-1557. |
R832526 (Final) |
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Lee J, Yamakoshi Y, Hughes JB, Kim J-H. Mechanism of C60 photoreactivity in water: fate of triplet state and radical anion and production of reactive oxygen species. Environmental Science & Technology 2008;42(9):3459-3464. |
R832526 (Final) |
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Lee J, Cho M, Fortner JD, Hughes JB, Kim J-H. Transformation of aggregated C60 in the aqueous phase by UV irradiation. Environmental Science & Technology 2009;43(13):4878-4883. |
R832526 (Final) |
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Zhang B, Cho M, Fortner JD, Lee J, Huang C-H, Hughes JB, Kim J-H. Delineating oxidative processes of aqueous C60 preparations: role of THF peroxide. Environmental Science & Technology 2009;43(1):108-113. |
R832526 (Final) |
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Supplemental Keywords:
C60, carbon nanotube, water treatment, coagulation, flocculation, sedimentation, jar test, ozone, UV, transformation, natural organic matter, isotherm, photochemistry, reactive oxygen species, THF, byproduct, toxicity, RFA, Health, Scientific Discipline, PHYSICAL ASPECTS, Water, Environmental Chemistry, Health Risk Assessment, Risk Assessments, Biochemistry, Physical Processes, Drinking Water, Engineering, Chemistry, & Physics, fate and transport, health effects, human health effects, carbon fullerene, epidemelogy, exposure, nanotechnology, other - risk assessment, particle exposure, community water system, ambient particle health effects, human exposure, engineered nanomaterials, toxicity, nanomaterials, water quality, cellular responses, drinking water contaminants, biochemical research, human health risk, drinking water systemProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.