Power generation from biomass is a substantial source of ashes, the extent of which depends on the type of biomass fuel and technology of combustion being used. The current study focuses on comparison of ashes with a special emphasis on hazardous organic compounds, particularly the polycyclic aromatic hydrocarbons (PAHs) fraction, present in ash. The reason is that ashes from combustion of wood or straw are considered as fertilizers in agricultural soils. Ash samples were therefore collected from power plants in the Czech Republic coming from combustion of wood chips, sawdust, bark and straw. The organic fraction was separated by extraction, the final determination of PAHs was performed by GC-UV. The total concentration of PAHs was found to be in the range 15-733 μ g/kg. These compounds are formed during the pyrolysis stage of the combustion process by the secondary ar omatization reactions in char at temperatures above 400 °C. The created PAHs are bound in the porous unburned carbon. For a more detailed qualitative analysis of other organic compounds the GC-MS was used. Higher and branched aliphatic hydrocarbons, ketones, amides and phthalates in the sample with the highest unburned carbon content were found., Pavel Straka and Martina Havelcová., and Obsahuje bibliografické odkazy
A combined sorbent was prepared by impregnation of lignite mined in the South Moravian Coalfield, Czech Republic, with chitosan. Sorption performance of the combined sorbent and the untreated lignite was tested for Co(II), Cu(II), and Cd(II) in equilibrium sorption experiments with respect to pH and metal concentration. The amount of metal retained by the sorbent was determined by instrumental neutron activation analysis in the short time irradiation mode with epithermal neutrons. For pH~5, sorption isotherms were determined and fitted using the Langmuir and Freundlich models. The results have been compared with those obtained previously for similar combined sorbent based on naturally oxidized coal mined in the Sokolov Basin, Czech Republic. It has been shown that the effect of chitosan on sorption efficiency of the chitosan-doped coal sorbents strongly depends on solution pH, and type of coal and metal., Martina Havelcová, Jiří Mizera, Vladimír Machovič, Lenka Borecká, Oldřich Přibyl and Ivana Krausová., and Obsahuje bibliografii