2006 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, 2006 through December 31, 2007
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 goal of this research is to develop nanoscale bimetallic particles (e.g., Fe-Pd, Fe-Ni, Fe-Ag) 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.

Specific objectives for this research include: (1) development of novel synthetic methods to produce nanoparticles with targeted sizes, enhanced reactivity, and subsurface transport characteristics; (2) evaluation of the iron nanoparticles for PBT transformation; (3) assessment of the injection, transport, reaction, and long-term performance characteristics of iron nanoparticles in porous media; and (4) microscopic analyses of soil-nanoparticle-PBT interactions.

Progress Summary:

State-of-the-art techniques of nanomaterial synthesis and characterization have been tested for the synthesis of novel bimetallic zero-valent iron (ZVI) nanoparticles for PBT treatment. The design principles of biomedical drug delivery reagents have been applied to derivitize the iron nanoparticle surface. For example, negatively charged polyelectrolytes have been found to be effective to enhance mobility of iron nanoparticles in groundwater. The synthesized nanoparticles have been assessed for their rate and extent of PBT transformation. Model compounds selected for this research include: PCBs, hexachlorocyclohexanes (HCHs), chlorinated benzenes, and phenols. Particularly, progress in various aspects of our 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 (TEM), X-ray diffraction (XRD), high resolution X-ray photoelectron spectroscopy (HR-XPS), X-ray absorption near edge structure (XANES), and acoustic/electroacoustic spectrometry. BET surface area, zeta (ζ) potential, isoelectric point (IEP), and solution Eh 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 (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 symbol 8.1 to 4.5. XPS confirmed the sorption of PV3A on the nanoparticle surface and also the existence of ZVI (Fe0) in the nZVI mass. The appreciably smaller mean particle sizes and ability to remain in suspension should translate into greatly improved subsurface mobility potential.

Results of this work will be in publication soon (Sun, et al. 2007).

Application of ZVI Nanoparticles for Treatment of Hexachlorocyclohexanes (HCHs)

In this work, groundwater and aquifer samples from a site contaminated by hexachlorocyclohexanes (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 μg/L. In general, batch experiments with 2.2–27.0 g/L iron nanoparticles showed that more than 95% of the HCHs were removed from solution within 48 hours. The reactivity trend γ symbol 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 dihaloelimination steps. Rate constants normalized to the iron surface area concentration, kN1, ranged from 5.4x10-4 to 8.8x10-4 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 U.S. Environmental Protection Agency (EPA) Science To Achieve Results (STAR) project.

Partial results have been included in Li, et al. (2006). Two additional manuscripts on this topic are under review.

Stabilization of Biosolids with Nanoscale nZVI

Biosolids are the treated organic residuals, also known as sludge, that are generated from domestic wastewater treatment plants. According to the EPA, over 7 million tons (dry weight) of biosolids are generated every year in the United States by the more than 16,000 wastewater treatment plants, and a large portion of these biosolids is disposed of on land. Nuisance odors, potential pathogen transmission, and the presence of toxic and persistent chemicals and metals in biosolids have, for the most part, limited the use of land applications.

We have tested ZVI nanoparticles for the treatment and stabilization of biosolids. Iron nanoparticles have been shown to form stable and nonvolatile surface complexes with malodorous sulfur compounds such as hydrogen sulfide and methyl sulfides. The end products from the nanoparticle reactions are iron oxides and oxyhydroxides, similar to the ubiquitous iron minerals in the environment. Due to the large surface area and high surface reactivity, only a relatively low dose (<0.1% wt) of iron nanoparticles is needed for effective biosolids stabilization.

The iron nanoparticle technology may thus offer an economically and environmentally sustainable and unique solution to one of the most vexing environmental problems. This work has been recently published (Li, et al., 2007).

nZVIThe Core-Shell Structure and Unique Properties for Ni(II) Sequestration

More recent research suggests that iron nanoparticles function as a sorbent and a reductant for the sequestration of Ni(II) in water. A relatively high capacity of nickel removal is observed (0.13 g Ni/g Fe, or 4.43 meq Ni(II)/g), which is over 100% higher than the best inorganic sorbents available. HR-XPS confirms that the ZVI nanoparticles have a core-shell structure and exhibit characteristics of both hydrous iron oxides (i.e., as a sorbent) and metallic iron (i.e., as a reductant). Ni(II) quickly forms a surface complex and is then reduced to metallic nickel on the nanoparticle surface. The dual properties of iron nanoparticles may offer efficient and unique solutions for the separation and transformation of metal ions and other environmental contaminants.

This work has been recently published (Li and Zhang, 2006).

Sequestration of Metal Cations with ZVI NanoparticlesA Study with HR-XPS

In this work, applications of nZVI for removal of metal cations in water are investigated with the result that nZVI has much larger capacity than conventional materials for the sequestration of Zn(II), Cd(II), Pb(II), Ni(II), Cu(II), and Ag(I). Characterizations with HR-XPS confirm that the iron nanoparticles have a core-shell structure, which leads to exceptional properties for concurrent sorption and reductive precipitation of metal ions. For metal ions such as Zn(II) and Cd(II) with standard potential E0 very close to or more negative than that of iron (-0.41 V), the removal mechanism is sorption/surface complex formation. For metals with E0 greatly more positive than iron, for instance Cu(II), Ag(I), and Hg(II), the removal mechanism is predominantly reduction. Metals with E0 slightly more positive than iron, for example Ni(II) and Pb(II), can be immobilized at the nanoparticle surface by both sorption and reduction. The dual sorption and reduction mechanisms on top of the large surface of nanosized particles produce rapid reaction and high removal efficiency, and offer nZVI as a highly efficient material for treatment and immobilization of toxic heavy metals.

This work has been recently accepted for publication (Li and Zhang, accepted, 2007).

Future Activities:

Our work plan for the next 12-18 months includes the following three aspects of nZVI nanoparticles:

(1) Reaction mechanisms of nZVI with PBTs. While chlorinated aliphatic C1 and C2 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 research with micro- and milli-meter iron particles reported little or no reactions. We plan to examine the reactions of nZVI with a series of chlorinated benzene. Additional study is also planned on the degradation of lindane (g-hexachlorocyclohexanes, g-HCH), one of the most widely used organochlorine pesticides.

(2) Transport and reactions of the nanoparticles in porous media will be studied in laboratory soil columns. The 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.

(3) Zero-valent metal nanoparticles supported on various substrates will be synthesized and investigated.While 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 reagents 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.

References:

Li XQ, Elliott DW, Wei-xian Zhang. Zero-valent iron nanoparticles for abatement of environmental pollutants: materials and engineering aspects. Critical Reviews in Solid State and Materials Sciences 2006;31:111-122.

Li, XQ and Zhang, WX.. Iron Nanoparticles: Core-shell structure and unique properties for Ni (II) sequestration. Langmuir 2006;22(10):4638-4642.

Li, XQ, Brown DG, and Zhang, WX. Iron particles for stabilization of biosolids. Journal of Nanoparticle Research 2007;9(2):233-243.

Sun Y-P, Li X-q, Cao J, Zhang W-x, Wang HP. Characterization of zero-valent iron nanoparticles. Advances in Colloid and Interface Science 2006;120(1-3):47-56.

Sun Y, Wang P, Zhang WX. 2007. Dispersion and transport of iron nanoparticles in porous media. Colloids and Surfaces A (accepted, 2007).


Journal Articles on this Report : 15 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 Li X-Q, Elliott DW, Zhang W-X. Zero-valent iron nanoparticles for abatement of environmental pollutants: materials and engineering aspects. Critical Reviews in Solid State and Materials Sciences 2006;31(4):111-122. GR832225 (2006)
    GR832225 (Final)
  • Full-text: gitech-Full Text PDF
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  • Abstract: Taylor&Francis-Abstract
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  • Journal Article Li X-Q, Brown DG, Zhang W-X. Stabilization of biosolids with nanoscale zero-valent iron (nZVI). Journal of Nanoparticle Research 2007;9(2):233-243. GR832225 (2006)
    GR832225 (Final)
  • Full-text: Springer-Full Text PDF
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  • Abstract: Springer-Abstract
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  • Journal Article Li X-Q, Zhang W-X. Sequestration of metal cations with zerovalent iron nanoparticles – a study with high resolution X-ray photoelectron spectroscopy (HR-XPS). Journal of Physical Chemistry C 2007;111(19):6939-6946. GR832225 (2006)
    GR832225 (Final)
  • 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 Lien H-L, Zhang W-X. Removal of methyl tert-butyl ether (MTBE) with Nafion. Journal of Hazardous Materials 2007;144(1-2):194-199. GR832225 (2006)
    GR832225 (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 Lien H-L, Elliott DW, Sun Y-P, Zhang W-X. Recent progress in zero-valent iron nanoparticles for groundwater remediation. Journal of Environmental Engineering and Management 2006;16(6):371-380. GR832225 (2006)
    GR832225 (Final)
  • Full-text: JEEM-Full Text PDF
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  • Abstract: JEEM-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, Zhang W-X, Wang HP. A method for the preparation of stable dispersion of zero-valent iron nanoparticles. Colloids and Surfaces A: Physicochemical and Engineering Aspects 2007;308(1-3):60-66. GR832225 (2006)
    GR832225 (Final)
  • Abstract: ScienceDirect-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, and sediments,, 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
  • 2005 Progress Report
  • 2007
  • Final Report