Sökning: "EXAFS"

Visar resultat 21 - 25 av 46 avhandlingar innehållade ordet EXAFS.

1. 21. Coordination Chemistry of Monocarboxylate and Aminocarboxylate Complexes at the Water/Goethite Interface

   Författare :Katarina Norén; Per Persson; Staffan Sjöberg; Stephan J. Hug; Umeå universitet; []
   Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; Acetate; benzoate; adsorption; surface complex; ternary surface complexes; ATR-FTIR spectroscopy; EXAFS spectroscopy.; cyclohexanecarboxylate; sarcosine; MIDA; EDDA; EDTA; gallium III ; goethite; mineral surface; Chemistry; Kemi;

   Sammanfattning : This thesis is a summary of five papers with focus on adsorption processes of various monocarboxylates and aminocarboxylates at the water/goethite interface. Interaction of organic acids at the water/mineral interfaces are of importance in biogeochemical processes, since such processes have potential to alter mobility and bioavailability of the acids and metal ions. LÄS MER

3. 22. Structure and bonding of sulfur-containing molecules and complexes

   Författare :Emiliana Damian Risberg; Magnus Sandström; Ingmar Persson; Tsun-Kong Sham; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Sulfur species; x-ray absorption and vibrational spectroscopy; TP-DFT calculations; Chemistry; Kemi; strukturkemi; Structural Chemistry;

   Sammanfattning : Synchrotron-based spectroscopic techniques enable investigations of the many important biological and environmental functions of the ubiquitous element sulfur. In this thesis the methods for interpreting sulfur K-edge X-ray absorption near edge structure (XANES) spectra are developed and applied for analyses of functional sulfur groups. LÄS MER

4. 23. Modeling of glyphosate and metal-glyphosate speciation in solution and at solution-mineral interfaces

   Författare :Caroline Jonsson; Staffan Sjöberg; Per Persson; Bernd Nowack; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; herbicide; glyphosate; surface complexation model; speciation; goethite; aged gamma-alumina; bayerite; manganite; cadmium II ; aluminium III ; potentiometric titration; adsorption; Chemistry; Kemi;

   Sammanfattning : Glyphosate (N-(phosphonomethyl)glycine, PMG, H3L) is a widely used organophosphorous herbicide. It interacts with metal ions and mineral surfaces, which may affect its mobility, degradation and bioavailability in the environment. However, these interactions are far from fully understood. LÄS MER

5. 24. New insights into solubility control mechanisms and the role of particle- and colloid-facilitated transport of metals in contaminated soils

   Författare :Åsa Löv; Sveriges lantbruksuniversitet; Sveriges lantbruksuniversitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

   Sammanfattning : Particle- and colloid-mediated transport of metals can be an important leaching pathway in contaminated soils, making it necessary to include this process in risk assessments of contaminant transport. In this thesis, mechanisms involved in transport of particulate, colloidal and truly dissolved lead, chromium, zinc, arsenic and antimony were studied in an irrigation experiment performed on intact soil columns from four historically contaminated soils. LÄS MER

7. 25. Hydration, solvation and hydrolysis of multicharged metal ions

   Författare :Natallia Torapava; Sveriges lantbruksuniversitet; Sveriges lantbruksuniversitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

   Sammanfattning : Structures of hydrated, solvated and hydrolyzed multicharged metal ions are determined by EXAFS and LAXS in solution, and by X-ray crystallography and EXAFS in the solid state. During hydrolysis, the nine-coordinate hydrated thorium(IV) ion is first transformed to a dimer, [Th₂(μ²-OH)₂(H₂O)₁₂]⁶⁺, then to a tetramer, [Th₄(μ²-OH)₈(H₂O)₁₆]⁸⁺, and finally to a hexamer, [Th₆(μ³-O₈)(H₂O)n]⁸⁺ with increasing pH and thorium(IV) concentration in an aqueous solution. LÄS MER