Projekt

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Iron(III) precipitates formed by iron(II) oxidation in natural waters: Structure, reactivity and impact on arsenic

Titel Englisch Iron(III) precipitates formed by iron(II) oxidation in natural waters: Structure, reactivity and impact on arsenic
Gesuchsteller/in Voegelin Andreas
Nummer 132123
Förderungsinstrument Projektförderung (Abt. I-III)
Forschungseinrichtung Eawag
Hochschule Eidg. Anstalt für Wasserversorgung, Abwasserreinigung und Gewässerschutz - EAWAG
Hauptdisziplin Andere Gebiete der Umweltwissenschaften
Beginn/Ende 01.02.2011 - 31.03.2014
Bewilligter Betrag 198'448.00
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Alle Disziplinen (4)

Disziplin
Andere Gebiete der Umweltwissenschaften
Geochemie
Hydrologie, Limnologie, Glaziologie
Bodenkunde

Keywords (12)

iron; arsenic; phosphate; colloids; nanoparticles; oxidation; precipitation; adsorption; coagulation; structure; X-ray absorption spectroscopy; electron microscopy

Lay Summary (Englisch)

Lead
Lay summary
The oxidation of ferrous (Fe(II)) to ferric iron (Fe(III)) in waters containing phosphate, silicate, calcium (Ca) and trace elements results in short-range-ordered (SRO) Fe(III)-precipitates that control the cycling of major and trace elements at anoxic-oxic boundaries in natural and engineered systems. These precipitates largely vary in composition and degree of Fe(III) polymerization. Their structural diversity and resulting differences in colloidal and chemical behavior however are still poorly understood. The proposed project takes advantage of state-of-the-art synchrotron X-ray absorption spectroscopy (XAS) and analytical electron microscopy (AEM) for the study of SRO Fe(III)-precipitates formed under widely varying chemical conditions. It thereby aims at achieving a new level of understanding regarding the formation, structure and stability of SRO Fe(III)-precipitates and their role in the biogeochemical cycling of major and trace elements. Such mechanistic knowledge is increasingly important for the quantitative description of nutrient and contaminant behaviour in aquatic systems and improved water resource use and water treatment. Specifically, the proposed research will focus on the following four research questions:1) How do the kinetics of Fe oxidation, precipitation, and aggregation/coagulation affect the types, structure and nanometer- to micrometer-scale spatial arrangement of SRO Fe(III)-precipitates?2) How does the composition, structure, and morphology of Fe(III)-Ca-phosphates and -arsenates formed by Fe(II) oxidation in presence of phosphate or/and arsenate vary as a function of solution chemistry?3) How does the composition, structure and morphology of different SRO Fe(III)-precipitates change during aging and how do these changes affect their solubility?4) How does Fe oxidation, precipitation and aging affect the co-oxidation and co-transformation of As and what are the implications for As removal in water treatment and for biogeochemical As cycling?To address these questions, Fe(II) (and As(III)) oxidation experiments will be designed that capture the complex interplay of key parameters (concentrations of Fe(II), phosphate, silicate, Ca, As (III) or As(V); solution pH; O2 partial pressure; ionic strength) while being controlled enough to allow for a quantitative description and modeling of the observed processes. XAS will provide molecular-level insight into precipitate structure from the perspective of local element coordination, and AEM into particle composition, structure, and morphology from the nanometer- to the micrometer scale.
Direktlink auf Lay Summary Letzte Aktualisierung: 21.02.2013

Verantw. Gesuchsteller/in und weitere Gesuchstellende

Mitarbeitende

Publikationen

Publikation
Dynamic Fe-precipitate formation induced by Fe(II) oxidation in aerated phosphate-containing water
Voegelin Andreas, Senn Anna-Caterina, Kaegi Ralf, Hug Stephan J., Mangold S., Dynamic Fe-precipitate formation induced by Fe(II) oxidation in aerated phosphate-containing water, in Geochimica et Cosmochimica Acta.

Zusammenarbeit

Gruppe / Person Land
Formen der Zusammenarbeit
Synchrotron ANKA, Karlsruher Institut für Technologie Deutschland (Europa)
- Publikation
- Forschungsinfrastrukturen

Wissenschaftliche Veranstaltungen

Aktiver Beitrag

Titel Art des Beitrags Titel des Artikels oder Beitrages Datum Ort Beteiligte Personen
Goldschmidt Conference 2014 Vortrag im Rahmen einer Tagung Structure, composition and arsenate uptake of Fe oxidation products 08.06.2014 Sacramento, Vereinigte Staaten von Amerika Voegelin Andreas; Kägi Ralf; Hug Stephan; Senn Anna-Caterina;
Goldschmidt Conference 2014 Vortrag im Rahmen einer Tagung Natural nanoparticles: Formation and impact on trace elements 08.06.2014 Sacramento, Vereinigte Staaten von Amerika Voegelin Andreas;
International Seminar "Dynamic Processes in Capillary Fringes" Vortrag im Rahmen einer Tagung Formation of Fe precipitates at dynamic redox interfaces and their effect on trace elements 24.02.2014 Karlsruhe, Deutschland Voegelin Andreas;
11th Swiss Geoscience Meeting Vortrag im Rahmen einer Tagung Composition and structure of fresh and aged Fe oxidation products 15.11.2013 Lausanne, Schweiz Hug Stephan; Senn Anna-Caterina; Voegelin Andreas; Kägi Ralf;
Goldschmidt Conference 2013 Vortrag im Rahmen einer Tagung Arsenic sequestration by fresh and aged Fe oxidation products 25.08.2013 Florence, Italien Hug Stephan; Kägi Ralf; Senn Anna-Caterina; Voegelin Andreas;
Goldschmidt Conference 2013 Vortrag im Rahmen einer Tagung Composition and structure of fresh and aged Fe oxidation products 25.08.2013 Florence, Italien Hug Stephan; Senn Anna-Caterina; Voegelin Andreas; Kägi Ralf;
245th ACS National Meeting Vortrag im Rahmen einer Tagung Formation of iron(III)-phases and redox transformations upon aeration of natural and synthetic groundwaters containing Fe(II), silicate, phosphate, carbonate, and arsenic 07.04.2013 New Orleans, Vereinigte Staaten von Amerika Voegelin Andreas; Kägi Ralf; Hug Stephan; Senn Anna-Caterina;
6th IBP PhD Congress Poster Effects of dissolved P, Si and Ca on composition, structure and As uptake of fresh and aged Fe precipitates 05.04.2013 Dübendorf, Schweiz Senn Anna-Caterina; Voegelin Andreas; Kägi Ralf; Hug Stephan;
Monte Verità Conference "Iron Biogeochemistry - From Molecular Processes to Global Cycles" Vortrag im Rahmen einer Tagung Dynamic Fe precipitate formation during Fe(II) oxidation in phosphate-containing aqueous solutions 03.03.2013 Ascona, Schweiz Hug Stephan; Voegelin Andreas; Senn Anna-Caterina; Kägi Ralf;
Monte Verità Conference "Iron Biogeochemistry - From Molecular Processes to Global Cycles" Poster Effects of dissolved P, Si and Ca on composition, structure and As uptake of fresh and aged Fe precipitates 03.03.2013 Ascona, Schweiz Kägi Ralf; Voegelin Andreas; Senn Anna-Caterina; Hug Stephan;
10th Swiss Geoscience Meeting Vortrag im Rahmen einer Tagung Dynamic Fe precipitation by Fe(II) oxidation in water 16.11.2012 Bern, Schweiz Kägi Ralf; Hug Stephan; Senn Anna-Caterina; Voegelin Andreas;
10th Swiss Geoscience Meeting Poster Effects of P, Si and Ca on composition, structure and As uptake of fresh and aged Fe precipitates 16.11.2012 Bern, Schweiz Voegelin Andreas; Kägi Ralf; Senn Anna-Caterina;
4th ANKA / KNMF Joint Users Meeting Poster Dynamic Fe precipitate formation during Fe(II) oxidation in aerated phosphate-containing water 10.10.2012 Karlsruhe, Deutschland Voegelin Andreas; Senn Anna-Caterina; Hug Stephan; Kägi Ralf;
FIMIN-Workshop "Modelling of surface reactions of ferric (hydr)oxides" Poster ffects of dissolved P, Si and Ca on the composition and As uptake of Fe precipitates formed by Fe(II) oxidation by O2 08.10.2012 Bayreuth, Deutschland Voegelin Andreas; Hug Stephan; Senn Anna-Caterina; Kägi Ralf;
Eurosoil Conference 2012 Poster Phosphate-bearing Fe(III) precipitates forming by Fe(II) oxidation in water 02.07.2012 Bari, Italien Hug Stephan; Voegelin Andreas; Kägi Ralf; Schwarz Susanne;
Goldschmidt Conference 2012 Vortrag im Rahmen einer Tagung Dynamic precipitate formation during Fe(II) oxidation in aerated phosphate-containing water 24.06.2012 Montreal, Kanada Voegelin Andreas; Kägi Ralf;
3rd ANKA/KNMF Joint Users Meeting Poster New insight into the formation, structure and aging of iron oxidation products 13.10.2011 Karlsruhe, Deutschland Kägi Ralf; Schwarz Susanne; Hug Stephan; Voegelin Andreas;
Goldschmidt Conference 2011 Vortrag im Rahmen einer Tagung Nanoparticulate Fe(III)-precipitates forming by Fe(II) oxidation in water 14.08.2011 Prag, Tschechische Republik Voegelin Andreas; Hug Stephan; Kägi Ralf; Schwarz Susanne;


Verbundene Projekte

Nummer Titel Start Förderungsinstrument
113654 Arsenic Contamination of Paddy Soils through Irrigation Water in Bangladesh: Field Evidence and Investigation of Relevant Processes 01.01.2007 Projektförderung (Abt. I-III)
152993 Iron(III) precipitates formed by iron(II) oxidation in natural waters: Structure, reactivity and impact on arsenic 01.04.2014 Projektförderung (Abt. I-III)
124411 Diagenetic evolution and mineral composition of Fe/Mn layers in the sediments of Lake Baikal 01.08.2009 Projektförderung (Abt. I-III)
117933 Dynamics of Trace Metal Speciation in Periodically Reduced Soils 01.03.2008 Projektförderung (Abt. I-III)

Abstract

The oxidation of ferrous iron (Fe(II)) to ferric iron (Fe(III)) in waters containing phosphate, silicate, calcium (Ca) and trace elements results in short-range-ordered (SRO) Fe(III)-precipitates that control the cycling of major and trace elements at anoxic-oxic boundaries in natural and engineered systems. These precipitates largely vary in composition and degree of Fe(III) polymerization. Their structural diversity and resulting differences in colloidal and chemical behavior however are still poorly understood. Furthermore, although Fe(II) oxidation and Fe(III)-precipitates have long been studied, the full complexity of redox reactions involving Fe(II), reactive oxygen intermediates and trace elements, leading for example to co-oxidation of arsenic (As) and its incorporation into SRO Fe(III)-precipitates, has only received limited attention. The proposed project takes advantage of state-of-the-art synchrotron X-ray absorption spectroscopy (XAS) and analytical electron microscopy (AEM) for the study of SRO Fe(III)-precipitates formed under widely varying chemical conditions. It thereby aims at achieving a new level of understanding regarding the formation, structure and stability of SRO Fe(III)-precipitates and their role in the biogeochemical cycling of major and trace elements. Such mechanistic knowledge is increasingly important for the quantitative description of nutrient and contaminant behavior in aquatic systems and improved water resource use and water treatment. Specifically, the proposed research will focus on the following four research questions:1) How do the kinetics of Fe oxidation, precipitation, and aggregation/coagulation affect the types, structure and nanometer- to micrometer-scale spatial arrangement of SRO Fe(III)-precipitates?2) How does the composition, structure, and morphology of Fe(III)-Ca-phosphates and -arsenates formed by Fe(II) oxidation in presence of phosphate or/and arsenate vary as a function of solution chemistry?3) How does the composition, structure and morphology of different SRO Fe(III)-precipitates change during aging and how do these changes affect their solubility?4) How does Fe oxidation, precipitation and aging affect the co-oxidation and co-transformation of As and what are the implications for As removal in water treatment and for biogeochemical As cycling?To address these questions, Fe(II) (and As(III)) oxidation experiments will be designed that capture the complex interplay of key parameters (concentrations of Fe(II), phosphate, silicate, Ca, As (III) or As(V); solution pH; O2 partial pressure; ionic strength) while being controlled enough to allow for a quantitative description and modeling of the observed processes. XAS will provide molecular-level insight into precipitate structure from the perspective of local element coordination, and AEM into particle composition, structure, and morphology from the nanometer- to the micrometer scale.
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