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Mercury binding on soil components
Janko, Jiří ; Navrátil, Tomáš (advisor) ; Chrastný, Vladislav (referee)
In this work, a new approach to mercury speciation study on solid samples was tested and verified. This approach is different from commonly applied sequential extraction techniques. Mercury speciation was expressed as a stability constant K, describing the bonding equilibrium between mercury and solid. Stability constant K was measured on soil sample from Příbram, which was characterised in detail (chemical analysis, powder XRD diffraction, thermo desorption analyses). Using solution of potassium resp. ammonium bromide, iodide and thiocyanate the K value was quantified in a wide concentration range. We showed that in mercury in studied sample was present in a single specie with pK 36. We discussed the effect of extractant concentration and experimental setting on resulting K. The result of extraction experiments was in accordance with thermo desorption results confirming mercury present as one specie bound onto clay matrices. As a profound difference in approach to common speciation extraction techniques, in which a set of operationally defined mercury fractions is obtained, the K value obtained in this work represents a thermodynamical parameter feasible for further mathematical processing. Thiocyanate was identified as a useful anion for extraction studies of mercury speciation on solid...
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Mercury binding on soil components
Janko, Jiří ; Navrátil, Tomáš (advisor) ; Chrastný, Vladislav (referee)
In this work, a new approach to mercury speciation study on solid samples was tested and verified. This approach is different from commonly applied sequential extraction techniques. Mercury speciation was expressed as a stability constant K, describing the bonding equilibrium between mercury and solid. Stability constant K was measured on soil sample from Příbram, which was characterised in detail (chemical analysis, powder XRD diffraction, thermo desorption analyses). Using solution of potassium resp. ammonium bromide, iodide and thiocyanate the K value was quantified in a wide concentration range. We showed that in mercury in studied sample was present in a single specie with pK 36. We discussed the effect of extractant concentration and experimental setting on resulting K. The result of extraction experiments was in accordance with thermo desorption results confirming mercury present as one specie bound onto clay matrices. As a profound difference in approach to common speciation extraction techniques, in which a set of operationally defined mercury fractions is obtained, the K value obtained in this work represents a thermodynamical parameter feasible for further mathematical processing. Thiocyanate was identified as a useful anion for extraction studies of mercury speciation on solid...
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Colloids in landfill waters and leachates
Janko, Jiří ; Ettler, Vojtěch (advisor) ; Matura, Marek (referee)
Contamination of surface water or groundwater by metals and/or metalloids, originating from landfill leachates is environmental concern in the vicinity of landfills designed for disposal for municipal solid waste (MSW). It is known that many organic compounds and metals/metalloids can be associated with colloids of the size 1 nm-1 μm. This relationship is mainly caused by the total surface area of colloids and consequently their binding capacity for contaminants occuring in the aqueous environment. In order to identify these associations in landfill leachates a cascade frontal filtration/ultra filtration is often adopted. Colloids obtained by this size-fractionation can be further studied by scanning electron microscope (SEM) or transmission electron microscope (TEM) coupled to energy dispersive spectroscopy (EDS). Typical example is a Vejen landfill in Denmark, which has been extensively studied, where leachate samples exhibited significant proportion of total metal content to be associated to colloids - Cd: 38-45%, Ni: 27-56%, Zn: 24-45%, Cu: 86-95% a Pb: 96-99%. Whereas Cd, Zn and Ni were mostly associated with smaller colloids (1-10 nm), other metals like Pb and Cu were bound to colloids of the size > 10 nm. A number of investigations from other landfill sites indicated similar results. Powered by TCPDF...
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