Sökning: "exafs"
Visar resultat 21 - 25 av 46 avhandlingar innehållade ordet exafs.
21. Coordination Chemistry of Monocarboxylate and Aminocarboxylate Complexes at the Water/Goethite Interface
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
22. Structure and bonding of sulfur-containing molecules and complexes
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
23. Modeling of glyphosate and metal-glyphosate speciation in solution and at solution-mineral interfaces
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
24. New insights into solubility control mechanisms and the role of particle- and colloid-facilitated transport of metals in contaminated soils
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
25. Hydration, solvation and hydrolysis of multicharged metal ions
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