title: Electron efficiency of nZVI does not change with variation of environmental parameters.
abstract: Nanoscale zero-valent iron particles (nZVI) are already applied for in-situ dechlorination of halogenated organic contaminants in the field. We performed batch experiments whereby trichloroethene (TCE) was dehalogenated by nZVI under different environmental conditions that are relevant in practice. The tested conditions include different ionic strengths, addition of polyelectrolytes (carboxymethylcellulose and ligninsulphonate), lowered temperature, dissolved oxygen and different particle contents. Particle properties were determined by Mössbauer spectroscopy, XRD, TEM, SEM, AAS and laser obscuration time measurements. TCE dehalogenation and H2 evolution were decelerated by reduced ionic strength, addition of polyelectrolytes, temperature reduction, the presence of dissolved oxygen and reduced particle content. The partitioning of released electrons between reactions with the contaminant vs. with water (selectivity) was low, independent of the tested conditions. Basically out of hundred electrons that were released via nZVI oxidation only 3.1±1.4 were used for TCE dehalogenation. Even lower selectivities were observed at TCE concentrations below 3.5 mg l(-1), hence particle modifications and/or combination of nZVI with other remediation technologies seem to be necessary to reach target concentrations for remediation. Our results suggest that selectivity is particle intrinsic and not as much condition dependent, hence particle synthesis and potential particle modifications of nZVI particles may be more important for optimization of the pollutant degradation rate, than tested environmental conditions.
authors.affiliation: AIT Austrian Institute of Technology GmbH, Konrad-Lorenz-Straße 24, 3430 Tulln a.d. Donau, Austria. Electronic address: philipp.schoeftner@ait.ac.at.
authors.forename: Philipp
authors.initials: P
authors.lastname: Schöftner
authors.affiliation: AIT Austrian Institute of Technology GmbH, Konrad-Lorenz-Straße 24, 3430 Tulln a.d. Donau, Austria.
authors.forename: Georg
authors.initials: G
authors.lastname: Waldner
authors.affiliation: Salzburg University, FB Materialforschung und Physik, Hellbrunnerstr. 34, 5020 Salzburg, Austria. Electronic address: werner.lottermoser@sbg.ac.at.
authors.forename: Werner
authors.initials: W
authors.lastname: Lottermoser
authors.affiliation: Technical University of Vienna, Universitäre Service-Einrichtung für Transmissionselektronenmikroskopie - USTEM. Electronic address: stoeger@ustem.tuwien.ac.at.
authors.forename: Michael
authors.initials: M
authors.lastname: Stöger-Pollach
authors.affiliation: Keller Grundbau Ges. mbH, Mariahilfer Straße 127a, 1150 Vienna, Austria. Electronic address: p.freitag@kellergrundbau.at.
authors.forename: Peter
authors.initials: P
authors.lastname: Freitag
authors.affiliation: AIT Austrian Institute of Technology GmbH, Konrad-Lorenz-Straße 24, 3430 Tulln a.d. Donau, Austria. Electronic address: thomas.reichenauer@ait.ac.at.
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Reichenauer
mesh_terms: D004583:Electrons; D007501:Iron / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D008956:Models, Chemical
chemical_list: D007501:Iron
keywords: Dechlorination; Halogenated hydrocarbons; TCE; nZVI