Project
Back to overview
Iron(III) precipitates formed by iron(II) oxidation in natural waters: Structure, reactivity and impact on arsenic
English title |
Iron(III) precipitates formed by iron(II) oxidation in natural waters: Structure, reactivity and impact on arsenic |
Applicant |
Voegelin Andreas
|
Number |
132123 |
Funding scheme |
Project funding
|
Research institution |
Swiss Federal Institute of Aquatic Science and Technology (EAWAG)
|
Institution of higher education |
Swiss Federal Institute of Aquatic Science and Technology - EAWAG |
Main discipline |
Other disciplines of Environmental Sciences |
Start/End |
01.02.2011 - 31.03.2014 |
Approved amount |
198'448.00 |
Show all
All Disciplines (4)
Other disciplines of Environmental Sciences |
Hydrology, Limnology, Glaciology |
Keywords (12)
iron; arsenic; phosphate; colloids; nanoparticles; oxidation; precipitation; adsorption; coagulation; structure; X-ray absorption spectroscopy; electron microscopy
Lay Summary (English)
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.
|
Responsible applicant and co-applicants
Employees
Publications
Voegelin Andreas, Senn Anna-Caterina, Kaegi Ralf, Hug Stephan J., Mangold S. (2013), Dynamic Fe-precipitate formation induced by Fe(II) oxidation in aerated phosphate-containing water, in
Geochimica et Cosmochimica Acta, 117, 216-231.
Collaboration
Synchrotron ANKA, Karlsruher Institut für Technologie |
Germany (Europe) |
|
- Publication - Research Infrastructure |
Scientific events
Active participation
Title |
Type of contribution |
Title of article or contribution |
Date |
Place |
Persons involved |
Goldschmidt Conference 2014
|
Talk given at a conference
|
Natural nanoparticles: Formation and impact on trace elements
|
08.06.2014
|
Sacramento, United States of America
|
Voegelin Andreas;
|
International Seminar "Dynamic Processes in Capillary Fringes"
|
Talk given at a conference
|
Formation of Fe precipitates at dynamic redox interfaces and their effect on trace elements
|
24.02.2014
|
Karlsruhe, Germany
|
Voegelin Andreas;
|
245th ACS National Meeting
|
Talk given at a conference
|
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, United States of America
|
Voegelin Andreas; Senn Anna-Caterina; Hug Stephan; Kägi Ralf;
|
Monte Verità Conference "Iron Biogeochemistry - From Molecular Processes to Global Cycles"
|
Talk given at a conference
|
Dynamic Fe precipitate formation during Fe(II) oxidation in phosphate-containing aqueous solutions
|
03.03.2013
|
Ascona, Switzerland
|
Senn Anna-Caterina; Hug Stephan; Voegelin Andreas; 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, Switzerland
|
Voegelin Andreas; Senn Anna-Caterina; Kägi Ralf; Hug Stephan;
|
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, Germany
|
Senn Anna-Caterina; Voegelin Andreas; Hug Stephan; Kägi Ralf;
|
Goldschmidt Conference 2012
|
Talk given at a conference
|
Dynamic precipitate formation during Fe(II) oxidation in aerated phosphate-containing water
|
24.06.2012
|
Montreal, Canada
|
Voegelin Andreas; Kägi Ralf;
|
Associated projects
Number |
Title |
Start |
Funding scheme |
113654
|
Arsenic Contamination of Paddy Soils through Irrigation Water in Bangladesh: Field Evidence and Investigation of Relevant Processes |
01.01.2007 |
Project funding |
152993
|
Iron(III) precipitates formed by iron(II) oxidation in natural waters: Structure, reactivity and impact on arsenic |
01.04.2014 |
Project funding |
124411
|
Diagenetic evolution and mineral composition of Fe/Mn layers in the sediments of Lake Baikal |
01.08.2009 |
Project funding |
117933
|
Dynamics of Trace Metal Speciation in Periodically Reduced Soils |
01.03.2008 |
Project funding |
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.
-