A5079041687- Radioactive element chemistry and processing
- Nuclear Materials and Properties
- Radioactive contamination and transfer
- Chemical Synthesis and Characterization
- Nuclear and radioactivity studies
- Nuclear materials and radiation effects
- Geochemistry and Elemental Analysis
- Extraction and Separation Processes
- Graphite, nuclear technology, radiation studies
- Analytical chemistry methods development
- Groundwater flow and contamination studies
- Radioactivity and Radon Measurements
- Nuclear reactor physics and engineering
- Clay minerals and soil interactions
- Field-Flow Fractionation Techniques
- Minerals Flotation and Separation Techniques
- Geochemistry and Geologic Mapping
- Iron oxide chemistry and applications
- X-ray Spectroscopy and Fluorescence Analysis
- Rare-earth and actinide compounds
- Soil and Unsaturated Flow
- Nuclear Physics and Applications
- Concrete and Cement Materials Research
- Lanthanide and Transition Metal Complexes
- Mine drainage and remediation techniques
Karlsruhe Institute of Technology
2016-2025
Federal Office for the Safety of Nuclear Waste Management
2006-2024
Bergmann und Partner Rechtsanwälte
2022
Karlsruhe University of Education
2014-2018
Kerntechnische Entsorgung Karlsruhe (Germany)
2014-2015
FZI Research Center for Information Technology
2002-2012
Saarland University
1991-2012
Institute of Plasma Physics
2008
Chinese Academy of Sciences
2008
Scherrer (Switzerland)
2008
To identify the effect of humic acid (HA) and fulvic (FA) on sorption mechanism Eu(III) organic−inorganic colloids in environment at a molecular level, surface adsorbed/complexed hydrous alumina, HA-, FA-hydrous alumina hybrids were characterized by using X-ray photoelectron spectroscopy (XPS) time-resolved laser fluorescence (TRLFS). The experiments performed 0.1 mol/L KNO3 or NaClO4 under ambient conditions. pH values varied between 2 11 fixed concentration 6.0 × 10−7 4.3 10−5 mol/L....
Abstract One of the long standing debates in actinide chemistry is level localization and participation 5 f valence orbitals covalent bonds across series. Here we illuminate role uranium, neptunium plutonium chemical bonding using advanced spectroscopies: M 4,5 HR-XANES 3 d 4 RIXS. Results reveal that are active for uranium neptunium, shown by significant variations their evidenced spectra. In contrast, appear localized surprisingly insensitive to different environments. We envisage this...
Uranium redox states and speciation in magnetite nanoparticles coprecipitated with U(VI) for uranium loadings varying from 1000 to 10 000 ppm are investigated by X-ray absorption spectroscopy (XAS). It is demonstrated that the U M4 high energy resolution near edge structure (HR-XANES) method capable clearly characterize U(IV), U(V), existing simultaneously same sample. The contributions of three different quantified iterative transformation factor analysis (ITFA) method. L3 XAS transmission...
CAT-ACT-the hard X-ray beamline for CATalysis and ACTinide/radionuclide research at the KIT synchrotron radiation facility ANKA-is dedicated to spectroscopy, including "flux hungry" photon-in/photon-out correlative techniques combines state-of-the-art optics with a unique infrastructure radionuclide catalysis research. Measurements can be performed photon energies varying between 3.4 keV 55 keV, thus encompassing actinide M- L-edge or potassium K-edge up K-edges of lanthanide series such as...
The interaction of citrate with hydrated Portland cement and its main hydrates: C-S-H (0.8 ≤ Ca/Si 1.4), ettringite, monosulfo-, hemi- monocarboaluminate is investigated. solubility citrate-AFm citrate-AFt was determined. Batch sorption experiments at pH = 13.2 showed that sorbs relatively strongly on AFm phases ettringite. Citrate sorbed only the outer surfaces sites monosulfoaluminate, ettringite resulting in a low capacity ≈5–8 mmol/kg, while case hemicarboaluminate occurred also...
The present paper describes the surface complexation behaviour of trivalent metal ions, Am(III) and Eu(III), on well characterised γ-alumina. Experiments are conducted at different pH (4-8) ionic strength (0.001 - 0.1 M NaClO 4 ) either in presence or absence CO 2 . By varying ion concentration from 10 -9 to -4 mol/L, sorption isotherm is established under each given experimental condition. Different models applied results interpret appraise processes conditions. A comparison made with...
Since its inauguration in 2005, the INE-Beamline for actinide research at synchrotron source ANKA (KIT North Campus) provides dedicated instrumentation x-ray spectroscopic characterization of samples and other radioactive materials. R&D work beamline focuses on various aspects nuclear waste disposal within INE's mission to provide scientific basis assessing long-term safety a final repository. The is accessible radiochemistry community through proposal system European Union Integrated...
The size and shape of colloids released from a natural bentonite into low-mineralized groundwater are investigated using various colloid characterization methods. For the applied methods such as atomic force microscopy (AFM), laser-induced breakdown detection (UBD), photon correlation spectroscopy (PCS), flow field-flow fractionation coupled to ICP-mass spectrometric (FFFF-ICPMS), respective raw data have be corrected in order consider chemical composition well instrumental artifacts....
The natural association nature of the humic colloid-borne trace elements is investigated. Rare earth (REE) Th and U are chosen as naturally occurring representatives chemical homologues for actinides different oxidation states present in nuclear waste. Tri- tetravalent two investigated Gorleben groundwaters (Gohy-532 -2227) almost exclusively occur or fulvic species. Their desorption behavior from colloids examined unperturbed groundwater (pH ∼8) under anaerobic conditions (Ar/1% CO2) by...
Summary The influence of smectite colloids on the migration behaviour U(VI), Th(IV), Pu(IV), Am(III), Np(V), Sr(II) and Cs(I) is investigated within Colloid Radionuclide Retardation experiment (CRR). Two in situ experiments a well-characterized granitic fracture zone are carried out presence absence bentonite colloids. retardation observed field studies increases sequence Np(V)∼U(VI)<Sr(II)<Cs(I), where small fraction colloid borne breakthrough only stated for Am(III) Th/Pu(IV) mainly...
A high energy resolution x-ray absorption near-edge structure (XANES) spectroscopy study on ${\text{U}}^{4+}$ $({\text{UO}}_{2})$, ${\text{U}}^{5+}$ $([{\text{UO}}_{2}{\text{Py}}_{5}][{\text{KI}}_{2}{\text{Py}}_{2}])$, and ${\text{U}}^{6+}$ $[{\text{UO}}_{2}{({\text{NO}}_{3})}_{2}{({\text{H}}_{2}\text{O})}_{6}]$ demonstrates the potential of this experimental technique for qualitative/semiqualitative quantitative actinide speciation investigations. We observe a pre-edge feature with...
Abstract Sri Lanka has high background radiation due to naturally occurring radionuclides like U-238, Th-232, and K-40 containing minerals. This study investigates the radiological characteristics of soil samples from Matale District in central Lanka, focusing on thorium (Th) its potential mobility/bioavailability. Spectrometric data indicate that Th contributes most significantly elevated levels this area. Thorium, present at approximately 0.2 wt.% bulk soil, was analyzed across various...
Tc-gluconate complexes in aqueous systems were recently reported and characterized by Tc L3-edge X-ray absorption near-edge structure (XANES) measurements [Dardenne, K.; Inorg. Chem. 2021, 60, 12285–12298]. The puzzling result was that the XANES of sample containing Tc(IV)-gluconate species differs substantially from Tc(IV)O2(am,hyd) hydrous oxide reference sample, whereas K-edge spectra did not differ significantly. We studied this observation theoretically tracked unknown a three-step...
Summary Sorption of Cm(III) onto γ -alumina coated with humic acid (HA) is studied by the Time Resolved Laser Fluorescence Spectroscopy (TRLFS). The experiments are performed at 0.1 M NaClO 4 , 0.44 g/L -Al 2 O 3 10 mg/L HA and a metal ion concentration 2×10 -7 mol/L. At investigated pH range (4 to 10) completely sorbed γ-Al . excitation spectrum bound HA/ in wavelength 370-400 nm exhibits broad flat bands very different from those obtained for aquo Cm(III)- surface complex, respectively....