Bioorganotone - Bestimmung der physikochemischen Eigenschaften eines neuen Materials
Zusammenfassung der Projektergebnisse
Soil microorganisms actively interact with clay minerals, altering their composition. Clays, known for their cation-holding capacity, are used in barrier systems. Microbes and minerals serve as natural binders for contaminants. Microbes, living or dead, can absorb heavy metals extensively, aided by substances like siderophores and EPS. These substances, primarily polysaccharides and proteins, help in metal absorption. Metal biosorption involves various mechanisms, including adsorption and co-precipitation with exudates, yet these interactions remain poorly understood. Thus, this project focused on studying the interactions between clays and microorganisms and their exudates to prepare and characterize bioorganic-modified clays. In kaolinite-based bio-clays, the mineral particles were primarily coated with bioorganics, with limited or no interlayer penetration. The arrangement on the clay surface depended on the size and structure of the bioorganics and the distribution and activity of the surface sites (both basal and edge surfaces). At low loads of bioorganic molecules, the clay surface distribution was determined by the most active surface sites in form of an incomplete monolayer. At high loading levels, the bioorganic molecules were distributed in a denser arrangement, which resulted in a bilayer or multilayer composition on the surface. In montmorillonite bio-clays, the bioorganic materials were distributed on the outer surfaces and/or in the interlayer galleries of the mineral particles. The arrangement and distribution were a function of the type, size and quantity of the bioorganic molecules/ions as well as the activity and distribution of the interaction sites of the clay layers (both basal and edge surfaces) and the expansion capability of the montmorillonite. Smaller molecules such as lecithin and DFOB, as well as larger components of EPS (e.g. chitosan), easily replaced the inorganic cations from the expanded interlayer space. EPS and biomass interacted preferentially with the outer clay surfaces, but partially penetrated into the interlayer galleries. The new modified bio-clays were different in structure and physicochemical properties compared to the parent material. The applied methods provided a good overview of the morphological, structural and physicochemical changes of the modified bio-clays with different properties.
Projektbezogene Publikationen (Auswahl)
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Structure and properties of bioorganoclays – Perspective hybrid materials. Gemeinsame Jahrestagung der Deutschen Bodenkundlichen Gesellschaft und der Bodenkundlichen Gesellschaft der Schweiz, Bern, 26.-28. August.
Poggenburg, C., Schampera, B., Schippers, A., Awuah, L., Marchanka, A., Kaufhold, S., Bachmann, J. & Guggenberger, G.
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Geometry and molecular arrangement of phosphatidylcholine-montmorillonite bioclays via classical molecular dynamics simulation. Applied Clay Science, 198, 105815.
Grančič, Peter & Tunega, Daniel
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Hydrophobicity and Charge Distribution Effects in the Formation of Bioorganoclays. Minerals, 11(10), 1102.
Grančič, Peter & Tunega, Daniel
