Chemical composition of burnt smell caused by accidental fires: environmental contaminants

The chemical composition of the odors typical of fires has recently been deciphered. Basically the constituents are mixtures of acetophenone, benzyl alcohol, hydroxylated derivatives of benzaldehyde, methoxylated and/or alkylated phenols and naphthalene. This finding makes it possible to develop objective, practical analytic measurement methods for the burnt smell as a contribution to improving fire damage assessment and remediation monitoring. With the aid of an artificially produced burnt smell and a panel of testers the odor detection threshold of a test mixture was determined olfactometrically to 2 μg m⁻³. Using a defined burnt-smell atmosphere in a test chamber, analytical methods with active sampling, the adsorbents XAD 7 and TENAX TA, and GC/MS measurement were then optimized and tested with a view to being able to carry out sensitive quantitative measurement of burnt smells. A further practical method with particular application to the qualitative characterization of this odor is based on the use of a new SPME (solid-phase microextraction) field sampler with DVB/CAR/PDMS (divinylbenzene/Carboxen™/polydimethylsiloxane) fibers.     

Influence of heavy metals on the formation and the distribution behavior of PAH and PCDD/F during simulated fires

Combustion experiments were performed with an artificial fire load (polystyrene and quartz powder) in a laboratory scale incinerator in the presence of gaseous HCl to simulate accidental fire conditions. The aim of this investigation was to trace back the alterations of the formation and the distribution behavior of PAH and PCDD/PCDF to the presence of CuO or a mixture of metal oxides (CdO, CuO, Fe(2)O(3), PbO, MoO(3), ZnO). The total amount of the 16 PAH target compounds was reduced by the factor of 5-9 when the mixture of metal oxides was present rather than merely CuO. PAH patterns as well as their distribution behavior were significantly influenced by these oxides. In general, transportation inside the installation was enhanced for most of the 16 analyzed PAH. Only fluorene and dibenzo[a,h]anthracene were transported to a smaller extent. In contrast to PAH, total concentrations of PCDD were increased by factor 9 and of PCDF by factor 10, respectively, when CuO was present. Adding the mixture of metal oxides resulted in an increase of PCDD by factor 14 and of PCDF by factor 7. CuO and the mixture of metal oxides had a different influence on the PCDD/F homologue patterns. For instance, the HxCDF to OCDF ratio after incineration without any metal oxide was 1 to 6, whereas addition of CuO or the mixture of the metal oxides shifted the HxCDF to OCDF ratios towards 1 to 40 or 1 to 17, respectively. Combustion along with CuO increased transportation of higher chlorinated PCDF congeners, whereas the mixture of the metal oxides caused a strong decrease of PCDF distribution throughout the system.     

Recycling of flame retardants containing printed circuits: A study of the possible formation of polyhalogenated dibenzodioxins/-furans

The generation of halogenated dibenzo-p-dioxins/-furans could be expected during recycling of printed circuits containing flame retardants. The presence of precursor substances (e.g. flame retardants like tetrabromobis-phenol A or PCB), partly elevated temperatures, and catalytical effects of copper seem to represent typical formation conditions for “dioxins”. To control the possible contamination of granulated material and thus of work places, in a pilot plant a test run was carried out with a hammer mill and an impact grinder. The air samples examined did not contain PXDD/F residues and the shredded material was contaminated only with PBDD/F at very low concentrations (0.03 – 1.13 ng/g). A test with printed circuits under thermal stress up to 300 °C in an oven generated low amounts of PBDD/F (0.74 – 4.51 ng/g). These tests provide proof that printed circuits can be recycled.     

PSM in Böden:

The fate of pesticides in soil is incompletely described by the analytical determination of applied pesticides because a differentiation between the processes degradation and sorption which determine pesticide concentration in soils is not possible. By analyzing corresponding metabolites, degradation can be confirmed. Detailed mass balances considering the mineralization and formation of non-extractable residues are set up in closed model systems applying radiotracer techniques. This complex laboratory data can only be transferred to field conditions by mathematical modeling.     

Umwelt und Nachhaltigkeit im Jahr der Chemie

Ohne Zusammenfassung     

Retro-techno-economic evaluation of acetic acid production using cotton stalk as feedstock

In value-added chemical industries, use of agricultural wastes as raw materials remains to be a major challenge in commercialization due to lack of competitiveness with respect to petrochemical processes. This work presents the techno-economic analysis of a novel bioprocessing plant converting 356,400 MT/year cotton stalks into 147,000 MT/year acetic acid. A production scheme integrating lignin separation with the main bioconversion stages has been proposed. Techno-economic assessment was performed through economic feasibility and retro-techno-economic analysis (RTEA) methods. The RTEA method has been extended to include the estimation of research and development funding for improving economic feasibility. Carbon offset of the proposed technology has been estimated and carbon credit results have been incorporated into the economic feasibility metrics.     

Pestizide im Tabakrauch II. Pyrolyseverhalten von ausgewählten pestiziden beim Tabakrauchen

The fate of Lindan, DDT, Malathion, Monolinuron, Captan and Maneb during smoking process was studied and it was observed that the amount of unchanged pesticides in the mainstream smoke depends on steam volatility of the substances, while the vapor pressures have no significant influence.     

Vorkommen chlorierter Kohlenwasserstoffe in ausgewählten Umweltproben Nordgriechenlands (Xanthi)

Residues of persistent chlorinated hydrocarbons HCB, BHC isomers, Heptachlor and -epoxide, DDE, Aldrin, Dieldrin and PCBshave been analysed in selected environmental samples soil, grass roots, pine-needles, hen's eggs and sheep's milk from Northern Greece (Xanthi). Almost all samples have shown residues in a range of 0,1 – 10 ppb except eggs and milk, which have been partially contaminated with HCB (approx. 20 ppb), DDE (approx. 40 ppb) and Dieldrin (approx. 30 – 40 ppb) related to freshweight. The contamination levels have been in the same order of magnitude as in environmental samples from Germany except PCBs, which have been accumulated in German samples tendencially higher. All residues detected have been significantly lower than the limits allowed in food stuffs.