Vladimír Pekárek

Effects of oxygen on formation of PCB and PCDD/F on extracted fly ash in the presence of carbon and cupric salt

The effect of oxygen-nitrogen atmosphere (N2 + 10%O2, N2 + 1%O2 and 99.999% N2) on the formation of PCB, PCDD and PCDF by the de novo synthetic reactions in the system consisting of extracted fly ash (from municipal waste incinerators--MWI), activated carbon, CuCl2 x 2H2O and NaCl at 340 degrees C was studied. The content of PCDD/F for systems with 10%O2, 1%O2 and 99.999% N2 was decreasing and corresponded to 17,304, 5544, and 1437 ng/sample. In all studied systems the isomer OCDD/F was prevailing. The content of PCBs in the same system was also decreasing from 1214 to 166 ng/g. Formation of nonortho PCB was relatively high compared to the system where only nitrogen was present. The possible mechanism of formation is outlined.

Dechlorination of polychlorinated biphenyls, dibenzo-p-dioxins and dibenzofurans on fly ash

Dechlorination of commercial mixtures of polychlorinated biphenyls (PCB) as well as polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans (PCDF) on extracted and non-extracted fly ash obtained from municipal waste incinerator (MWI) was studied in closed systems under nitrogen atmosphere at temperatures of 260 degrees C and 340 degrees C. Decomposition results (given as the difference between PCB or PCDD/F molar amounts before and after the experiment (in %) due predominantly to dechlorination reactions) and detoxification data (expressed similarly but related to toxic PCB and PCDD/F congeners only and given in I-TEQ units) are reported. Detoxification of Delor 105/80T at 260 degrees C and 340 degrees C at a loading of 0.65 wt%, was 99.48% and 100%, respectively. The decomposition of Delor 103 at 340 degrees C and for the loading of 0.75 wt%, corresponded to 99.99%. The detoxification capability of PCDD/Fs on extracted and non-extracted fly ash for loading of 130 and 264 ng/0.4 g of fly ash at 340 degrees C made 96 and 98%, respectively.

The effect of oils on PAH, PCDD, PCDF, and PCB emissions from a spark engine fueled with leaded gasoline

The effect of synthetic and mineral oils on the formation of polyaromatic hydrocarbons (PAHs), polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), and biphenyls (PCBs) in emissions from a spark ignition engine was studied on a Skoda Favorit engine fueled with leaded gasoline. The test cycle simulated urban traffic conditions on a chassis dynamometer, in accordance with the ECC 83.00 test. The data for selected PAHs as well as PCDDs, PCDFs, and PCBs congener profiles are presented. PCDD/Fs emissions for an unused oil and the oil after 10000-km operation varied from 300 to 2000 fmol/m3, PCBs emissions from 75 to 178 pmol/m3, and PAHs emissions from 150 to 420 microg/m3. The content of PCBs in oils varied from 2 to 920 mg/kg.

Effect of fuels and domestic heating appliance types on emission factors of selected organic pollutants

This study reports on the first complex data set of emission factors (EFs) of selected pollutants from combustion of five fuel types (lignite, bituminous coal, spruce, beech, and maize) in six different domestic heating appliances of various combustion designs. The effect of fuel as well as the effect of boiler type was studied. In total, 46 combustion runs were performed, during which numerous EFs were measured, including the EFs of particulate matter (PM), carbon monoxide, polyaromatic hydrocarbons (PAH), hexachlorobenzene (HxCBz), polychlorinated dibenzo-p-dioxins and furans (PCDD/F), etc. The highest EFs of nonchlorinated pollutants were measured for old-type boilers with over-fire and under-fire designs and with manual stoking and natural draft. Emissions of the above-mentioned pollutants from modern-type boilers (automatic, downdraft) were 10 times lower or more. The decisive factor for emission rate of nonchlorinated pollutants was the type of appliance; the type of fuel plays only a minor role. Emissions of chlorinated pollutants were proportional mainly to the chlorine content in fuel, but the type of appliance also influenced the rate of emissions significantly. Surprisingly, higher EFs of PCDD/F from combustion of chlorinated bituminous coal were observed for modern-type boilers (downdraft, automatic) than for old-type ones. On the other hand, when bituminous coal was burned, higher emissions of HxCBz were found for old-type boilers than for modern-type ones.

Effect of reaction time on PCDD and PCDF formation by de novo synthetic reactions under oxygen deficient and rich atmosphere

The effect of reaction time on formation of polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans (PCDF) was studied under laboratory conditions in the system containing municipal waste incineration fly ash, activated carbon and copper chloride dihydrate at 300 degrees C in 99.999% N2 and N2 + 10% O2 atmosphere. The concentrations of tetra- to octa-chlorinated isomers as well as I-TEQ concentrations of toxic congeners are reported. The mechanism of PCDD and PCDF formation from chlorophenols and chlorinated biphenyls is discussed in the light of the time changes of PCDD/PCDF ratios.

Thermochemical properties and relative stability of polychlorinated biphenyls

The values of thermochemical quantities (enthalpy and Gibbs energy of formation, entropy and molar heat capacity) in the ideal gas state and dihedral angles for all 209 polychlorinated biphenyls were obtained by the Benson contribution method and ab initio calculations. The di-, tri- and tetra-ortho-chlorinated biphenyls are related with properties of WHO non-ortho- and mono-ortho-biphenyls in connection with their potential human toxicities.

The effect of transient operations on the levels and congener profiles of PCBz, PCPh and PCDD/F in raw flue gases of MSWI plant.

The concentrations and congener profiles of polychlorinated benzenes, phenols, dibenzo-p-dioxin and dibenzofurans, measured in raw flue gases of a real MSWI plant, are discussed in this paper. The data covers steady-state and transient operation conditions, including the memory effect period close to two shutdowns. The highest levels of concentrations of the pollutants were observed the first day after the shutdown with subsequent gradual decrease towards steady-state values. The conditions of the steady-state period prior to shutdown are decisive for the increase of start-up values, memory effect values and memory effect length. We found that the above-mentioned pollutants had a different length of the memory effect period. It can be concluded that under plant transient operation the formation of pollutants by the de novo synthesis is higher than under steady-state conditions.