A5045330091- Water Treatment and Disinfection
- Radioactive element chemistry and processing
- Microbial bioremediation and biosurfactants
- Iron oxide chemistry and applications
- Chemical Reactions and Isotopes
- Isotope Analysis in Ecology
- Chemical Analysis and Environmental Impact
- Toxic Organic Pollutants Impact
- Pharmaceutical and Antibiotic Environmental Impacts
- Environmental remediation with nanomaterials
- Groundwater and Isotope Geochemistry
- Analytical chemistry methods development
- Clay minerals and soil interactions
- Microbial Fuel Cells and Bioremediation
- Pesticide and Herbicide Environmental Studies
- Groundwater flow and contamination studies
- Electrochemical Analysis and Applications
- Marine and coastal ecosystems
- Metal-Catalyzed Oxygenation Mechanisms
- Advanced oxidation water treatment
- Wastewater Treatment and Nitrogen Removal
- Mass Spectrometry Techniques and Applications
- Chemical Synthesis and Characterization
- Extraction and Separation Processes
- Analytical Chemistry and Chromatography
Swiss Federal Institute of Aquatic Science and Technology
2016-2025
ETH Zurich
2015-2025
ZHAW Zurich University of Applied Sciences
2020
Helmholtz Zentrum München
2011-2017
University of Neuchâtel
2017
Agroscope
2017
Institute of Groundwater Ecology
2017
Technical University of Munich
2017
Oregon Health & Science University
2009
University of Iowa
2009
Water quality issues are a major challenge that humanity is facing in the twenty-first century. Here, we review main groups of aquatic contaminants, their effects on human health, and approaches to mitigate pollution freshwater resources. Emphasis placed chemical pollution, particularly inorganic organic micropollutants including toxic metals metalloids as well large variety synthetic chemicals. Some aspects waterborne diseases urgent need for improved sanitation developing countries also...
Contamination of soils and aquifers with (poly)nitroaromatic compounds ((P)NACs) is a widespread problem. This work demonstrates that (P)NACs such as the explosive 2,4,6-trinitrotoluene (TNT) can be completely reduced to corresponding aromatic polyamines by Fe(II) present at surface Fe(III)(hydr)oxides or, less efficiently, hydroquinone moieties (natural) organic matter in presence H2S. The reduction kinetics were investigated sterile batch systems well columns containing either FeOOH-coated...
Mineral-bound Fe(II) species represent important natural reductants of pollutants in the anaerobic subsurface. At clay minerals, three types fundamentally different chemical environments may be present simultaneously, i.e., structural Fe(II), complexed by surface hydroxyl groups, and bound ion exchange. We investigated accessibility reactivity these suspensions two minerals containing either ferrous iron-bearing nontronite or iron-free hectorite. Nitroaromatic compounds (NACs) exhibiting...
The factors controlling rates of contaminant reduction by magnetite (Fe3O4) are poorly understood. Here, we measured the three ArNO2 compounds particles ranging from highly oxidized (x = Fe2+/Fe3+ 0.31) to fully stoichiometric 0.50). Rates became almost 5 orders magnitude faster as particle stoichiometry increased x 0.31 0.50. To evaluate what was rate reduction, apparent 15N kinetic isotope effects (15N-AKIE) values for nitrobenzene and open-circuit potentials (EOCP). 15N-AKIE were greater...
Solid-phase microextraction (SPME) coupled to gas chromatography/isotope ratio mass spectrometry was used determine the delta15N and delta13C signatures of selected nitroaromatic contaminants such as explosive 2,4,6-trinitrotoluene (TNT) for derivation isotopic enrichment factors contaminant transformation. Parameters efficient extraction compounds (NACs) substituted anilines from water samples were evaluated by SPME-GC/MS. determined SPME-GC/IRMS elemental analyzer IRMS (EA-IRMS) in good...
Structural Fe in clay minerals is an important redox-active species many pristine and contaminated environments as well engineered systems. Understanding the extent kinetics of redox reactions involving Fe-bearing has been challenging due to inability relate structural Fe2+/Fetotal fractions fundamental properties, such reduction potentials (EH). Here, we overcame this challenge by using mediated electrochemical (MER) oxidation (MEO) characterize fraction (Fe2+/Fetotal) smectites over a wide...
Clay minerals often contain redox-active structural iron that participates in electron transfer reactions with environmental pollutants, bacteria, and biological nutrients. Measuring the redox properties of Fe clay using electrochemical approaches, however, has proven to be difficult due a lack reactivity between electrodes. Here, we overcome this limitation by one-electron-transfer mediating compounds facilitate vitreous carbon working electrode an cell. Using approach, electron-accepting...
Structural Fe in clay minerals is an important, albeit poorly characterized, redox-active phase found many natural and engineered environments. This work develops experimental approach to directly assess the redox properties of a Fe-bearing smectite (ferruginous smectite, SWa-1, 12.6 wt % Fe) with mediated electrochemical reduction (MER) oxidation (MEO). By utilizing suite one-electron-transfer mediating compounds facilitate electron transfer between structural SWa-1 working electrode, we...
Benzotriazoles are widely used domestic and industrial corrosion inhibitors have become omnipresent organic micropollutants in the aquatic environment. Here, range of aerobic biological degradation mechanisms benzotriazoles activated sludge was investigated. Degradation pathways were elucidated by identifying transient persistent transformation products batch experiments using liquid chromatography–high-resolution tandem mass spectrometry (LC-HR-MS/MS). In addition, initial reactions studied...
Iron is present in virtually all terrestrial and aquatic environments, where it participates redox reactions with surrounding metals, organic compounds, contaminants, microorganisms. The rates extent of these strongly depend on the speciation Fe2+ Fe3+ phases, although underlying reasons remain unclear. In particular, numerous studies have observed that associated iron oxide surfaces (i.e., oxide-associated Fe2+) often reduces oxidized contaminants much faster than aqueous alone. Here, we...
Electron transfer to ferric iron in (oxyhydr-)oxides (hereafter oxides) is a critical step many processes that are central the biogeochemical cycling of elements and pollutant dynamics. Understanding these requires analytical approaches allow for characterizing reactivity oxides toward reduction under controlled thermodynamic boundary conditions. Here, we used mediated electrochemical (MER) follow changes oxide extents rates during abiotic ferrous iron-induced transformation six-line...
Ferrous iron formed during microbial ferric reduction induces phase transformations of poorly crystalline into more and thermodynamically stable (oxyhydr)oxides. Yet, characterizing the resulting decreases in reactivity remaining oxide toward (i.e., its reducibility) has been challenging. Here, we used six-line ferrihydrite by Shewanella oneidensis MR-1 as a model system to demonstrate that mediated electrochemical (MER) allows directly following reducibility transformation goethite...
Reductive transformation reactions involving mineral-bound Fe2+ species are of great relevance for the fate groundwater contaminants. For clay minerals, which ubiquitously present in soils and sediments, factors determining reactivity structural surface-bound not well understood. We investigated availability suspensions chemically reduced montmorillonite (SAz-1) as oxidized nontronite (SWa-1, ferruginous smectite) using two acetylnitrobenzene isomers reactive probe compounds. The analyses...
The biogeochemical processes controlling the reductive transformation of contaminants in an anaerobic aquifer were inferred from relative reactivity patterns redox-sensitive probe compounds. fate five nitroaromatic compounds (NACs) was monitored under different redox conditions a landfill leachate plume sandy aquifer. Results field experiments (continuous injection and situ microcosms) compared to findings laboratory batch column (using matrix model systems for sulfate- iron-reducing...
Structural Fe(II) in clay minerals is an important source of electron equivalents for the reductive transformation contaminants anoxic environments. We investigated which factors control reactivity smectites including total Fe content, Fe(II)/total ratio, and excess negative charge localization using 10 nitroaromatic compounds (NACs) as reactive probe molecules. Based on evidence from this work previous spectroscopic studies redox reactions iron-rich smectites, we propose a kinetic model...
ADVERTISEMENT RETURN TO ISSUEPREVFeatureNEXTAssessing Transformation Processes of Organic Compounds Using Stable Isotope FractionationCompound-specific stable isotope analysis makes it possible to infer the origin and transformation pathways organic compounds.Thomas B. Hofstetter*, René P. Schwarzenbach, Stefano M. BernasconiView Author Information Swiss Federal Institute Technology (ETH) ZurichCite this: Environ. Sci. Technol. 2008, 42, 21, 7737–7743Publication Date (Web):October 30,...
Ferrous iron associated with clay minerals can be important for the reductive transformation of organic contaminants in anoxic soils and groundwaters. We investigated reactivity structural Fe(II) ferruginous smectite reduction a series polychlorinated alkanes (hexa-, penta-, 1,1,1,2-and 1,1,2,2-tetrachloroethane, carbon tetrachloride (CCl4)) laboratory batch reactors. Evaluation reaction kinetics, product distribution, C-isotope fractionation suggest that ethanes containing three alpha-Cl...