2005 Progress Report: Transformation of Halogenated PBTs with Nanoscale Bimetallic Particles

EPA Grant Number: GR832225
Alternative EPA Grant Number: R832225
Title: Transformation of Halogenated PBTs with Nanoscale Bimetallic Particles
Investigators: Zhang, Wei-xian
Institution: Lehigh University
EPA Project Officer: Hahn, Intaek
Project Period: January 1, 2005 through December 31, 2007 (Extended to December 31, 2008)
Project Period Covered by this Report: January 1, 2005 through December 31, 2006
Project Amount: $325,000
RFA: Exploratory Research to Anticipate Future Environmental Issues: Impacts of Manufactured Nanomaterials on Human Health and the Environment (2003) RFA Text |  Recipients Lists
Research Category: Nanotechnology , Health Effects , Hazardous Waste/Remediation , Health , Safer Chemicals

Objective:

The objective of this research project is to develop nanoscale bimetallic particles (e.g., Fe-Pd) with sizes in the range of 1-100 nm for treatment of hydrophobic, persistent bioaccumulative toxic compounds (PBTs) such as polychlorinated biphenyls (PCBs), DDT, and lindane.

Progress Summary:

State-of-the-art techniques of nanomaterial synthesis and characterization have been tested to synthesize novel bimetallic zero-valent iron (ZVI) nanoparticles for PBT treatment. The design principles of biomedical drug delivery reagents have been adapted to derivitize the iron nanoparticle surface. For example, negatively charged polyelectrolytes have been found to be effective for enhancing the mobility of iron nanoparticles in groundwater. The synthesized nanoparticles have been assessed for their rate and extent of PBT transformation. Model compounds selected for treatment in this research include: PCBs, hexachlorocyclohexanes (HCHs), chlorinated benzenes, and phenols. Progress in three aspects of this work is summarized in this progress report.

Characterization of ZVI Nanoparticles

In this work, a systematic characterization of the iron nanoparticles prepared with the method of ferric iron reduction by sodium borohydride was performed. This work confirms the core-shell structure of the ZVI nanoparticles. Particle size, size distribution, and surface composition were characterized by transmission electron microscopy, X-ray diffraction, high resolution X-ray photoelectron spectroscopy (XPS), X-ray absorption near edge structure, and acoustic/electroacoustic spectrometry. BET surface area, zeta (ζ) potential, isoelectric point (IEP), solution standard electrode potential, and pH were also measured. Methods and results obtained from this work may foster better understanding, facilitate information exchange, and contribute to further research and development of iron nanoparticles for environmental and other applications. Details can be found in Sun, et al. (2006).

Preparation of Mobile ZVI Nanoparticles

A method for the synthesis of fully dispersed and reactive nanoscale particles of ZVI has been developed. In this work, polyvinyl alcohol-co-vinyl acetate-co-itaconic acid (PV3A), a nontoxic and biodegradable surfactant, is utilized to disperse the nanoscale ZVI (nZVI). The addition of PV3A affected three key surface-related changes, which led to significant enhancements in particle stability and subsurface mobility potential. These included: (1) a reduction of the mean nZVI particle size from 105 nm to 15 nm, (2) a reduction of the zeta (ζ) potential from +20 mV to -80 mV at neutral pH, and (3) a shift of the IEP from pH @ 8.1 to 4.5. XPS confirmed the sorption of PV3A on the nanoparticle surface and the existence of ZVI (Fe0) in the nZVI mass. The appreciably smaller mean particle sizes and the ability to remain in suspension should translate into greatly improved subsurface mobility potential. Two publications on this work are under preparation.

Application of ZVI Nanoparticles for Treatment of Hexachlorocyclohexanes (HCHs)

In this work, groundwater and aquifer samples from a site contaminated by HCHs (C6H6Cl6) were exposed to nanoscale iron particles to evaluate the technology as a potential remediation method. The total HCH burden in site groundwater was approximately 1,500 mg/L. In general, batch experiments with 2.2-27.0 g/L iron nanoparticles showed that more than 95 percent of the HCHs were removed from solution within 48 hours. The reactivity trend γ @ α > β> δ was observed in terms of the rate of disappearance from solution. This trend appears to be correlated with the orientation (axial vs. equatorial) of the chlorine atoms lost in the dihalo elimination steps. Rate constants normalized to the iron surface area concentration, kN1, ranged from 5.4 x 10-4 to 8.8 x 10-4 L/m2-hr. The observed pseudo first-order rate constants (kobs) were in the range of 0.04–0.65 hr-1, comparable to previously determined values for lindane (γ-HCH). Post test extractions of the reactor contents detected little HCH remaining in solution or on the solid surfaces, reinforcing the contention that reaction rather than sorption was the operative mechanism for the HCH removal. This work demonstrates the potential of nZVI nanoparticles for PBT treatment, which is the focus of this EPA STAR project.

Two publications on this topic are in preparation.

Future Activities:

Our work plan for the next 12-18 months includes the three aspects of nZVI nanoparticles described below.

Reaction Mechanisms of nZVI With PBTs

Although chlorinated aliphatic compounds have been studied extensively, chlorinated aliphatic cyclic and aromatic compounds have received far less attention. Without doubt, chlorinated aliphatic cyclic and aromatic compounds are more complicated with lower solubility in water, react more slowly with nZVI, and often generate more intermediates and byproducts. Limited research indicates that iron nanoparticles do exhibit fairly high reactivity toward these compounds even though some researches with micro- and millimeter iron particles reported little reactions. We plan to exam the reactions of nZVI with a series of chlorinated benzene. Additional study is also planed on the degradation of lindane (γ-HCH), one of the most widely used organochlorine pesticides.

Transport and Reactions of the Nanoparticles in Porous Media

This will be studied in laboratory soil columns. Surface modified ZVI nanoparticles will be used in this work. Furthermore, fluorescent tagging methods will be used for detailed microscopic analysis of particle transport, deposition, and reaction in porous media.

Supported Zero-Valent Metal Nanoparticles

Although it is well recognized that zero-valent metal nanoparticles are powerful remediants for chlorinated organics and for reducible metal ions such as Cr(VI) and Pb(II), the colloidal chemistry of these particles is such that they tend to agglomerate and adhere strongly to soil surfaces. This is probably the single most important technical problem associated with nZVI application. We have adapted some of the design principles of biomedical drug delivery methods to the problem of improving the permeability of metal nanoparticles through soils. The supports investigated to date have been negatively charged to inhibit binding to clay platelets and other negatively charged soil particles. We have identified two promising support materials, hydrophilic carbon and poly(acrylic acid), for zero valent bimetallic particles. Both supports impart a negative surface charge to the colloidal metals, greatly enhancing the stability of aqueous suspensions and their permeability in model soils.


Journal Articles on this Report : 9 Displayed | Download in RIS Format

Other project views: All 68 publications 28 publications in selected types All 28 journal articles
Type Citation Project Document Sources
Journal Article Cao J, Clasen P, Zhang W-X. Nanoporous zero-valent iron. Journal of Materials Research 2005;20(12):3238-3243. GR832225 (2005)
GR832225 (2006)
GR832225 (Final)
R829625 (Final)
  • Abstract: Journal of Materials Research-Abstract
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  • Journal Article Cao J, Elliott D, Zhang W-X. Perchlorate reduction by nanoscale iron particles. Journal of Nanoparticle Research 2005;7(4-5):499-506. GR832225 (2005)
    GR832225 (2006)
    GR832225 (Final)
    R829625 (2003)
    R829625 (Final)
  • Full-text: CMS-Full Text PDF
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  • Abstract: Springer-Abstract
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  • Journal Article Cao J, Zhang W-X. Stabilization of chromium ore processing residue (COPR) with nanoscale iron particles. Journal of Hazardous Materials 2006;132(2-3):213-219. GR832225 (2005)
    GR832225 (2006)
    GR832225 (Final)
    R829625 (Final)
  • Abstract from PubMed
  • Full-text: ScienceDirect-Full Text HTML
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  • Abstract: ScienceDirect-Abstract
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  • Other: ScienceDirect-Full Text PDF
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  • Journal Article Li X-Q, Zhang W-X. Iron nanoparticles: the core-shell structure and unique properties for Ni(II) sequestration. Langmuir 2006;22(10):4638-4642. GR832225 (2005)
    GR832225 (2006)
    GR832225 (Final)
    R829625 (Final)
  • Abstract from PubMed
  • Abstract: ACS-Abstract
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  • Journal Article Lien H-L, Zhang W-X. Hydrodechlorination of chlorinated ethanes by nanoscale Pd/Fe bimetallic particles. Journal of Environmental Engineering-ASCE 2005;131(1):4-10. GR832225 (2005)
    GR832225 (2006)
    GR832225 (Final)
    R829625 (2003)
    R829625 (Final)
  • Full-text: National University of Kaohsiung-Full Text PDF
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  • Abstract: ASCE-Abstract
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  • Journal Article Mace C, Desrocher S, Gheorghiu F, Kane A, Pupeza M, Cernik M, Kvapil P, Venkatakrishnan R, Zhang W-X. Nanotechnology and groundwater remediation: a step forward in technology understanding. Remediation 2006;16(2):23-33. GR832225 (2005)
    GR832225 (2006)
    GR832225 (Final)
    R829625 (Final)
  • Abstract: Wiley Online-Abstract
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  • Journal Article Sun Y-P, Li X-Q, Cao JS, Zhang W-X, Wang HP. Characterization of zero-valent iron nanoparticles. Advances in Colloid and Interface Science 2006;120(1-3):47-56. GR832225 (2005)
    GR832225 (2006)
    GR832225 (Final)
    R829625 (Final)
  • Abstract from PubMed
  • Full-text: National Cheng Kung University-Full Text PDF
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  • Abstract: ScienceDirect-Abstract
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  • Journal Article Zhang W-X, Karn B. Nanoscale environmental science and technology: challenges and opportunities. Environmental Science & Technology 2005;39(5):94A-95A. GR832225 (2005)
    GR832225 (2006)
    GR832225 (Final)
    R829625 (Final)
  • Abstract from PubMed
  • Full-text: ES&T-Full Text PDF
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  • Abstract: ES&T-Abstract
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  • Journal Article Zhang W-X, Elliott DW. Applications of iron nanoparticles for groundwater remediation. Remediation 2006;16(2):7-21. GR832225 (2005)
    GR832225 (2006)
    GR832225 (Final)
    R829625 (Final)
  • Abstract: Wiley-Abstract
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  • Supplemental Keywords:

    ground water, nanoparticles, nanotechnology, organics, PBTs, pesticides, remediation, soil, sediments, bioengineering.,, RFA, Scientific Discipline, Waste, Sustainable Industry/Business, Remediation, Environmental Chemistry, Sustainable Environment, Technology for Sustainable Environment, Biochemistry, New/Innovative technologies, Environmental Engineering, nanoparticle remediation, decontamination, bioengineering, persistant bioaccumulative toxic compounds, biodegradation, remediation technologies, nanotechnology, environmental sustainability, bio-engineering, nanocatalysts, environmentally applicable nanoparticles, biotechnology, sustainability, nanoscale bimetallic particles, innovative technologies, nanoparticle based remediation

    Progress and Final Reports:

    Original Abstract
  • 2006 Progress Report
  • 2007
  • Final Report