Vapor Phase Emissions Research Articles

Characterization of PFAS Air Emissions from Thermal Application of Fluoropolymer Dispersions on Fabrics

ABSTRACT During thermal processes utilized in affixing fluoropolymer coatings to fibers and fabrics, coating components are vaporized. It is suspected that per- and polyfluoroalkyl substances (PFAS) from the dispersions may undergo chemical transformations at the temperatures used, leading to emitted PFAS thermal byproducts. It is important to characterize these emissions to support evaluation of resulting environmental and health impacts. In this study, a bench-scale system was built to simulate this industrial process via thermal application of dispersions to fiberglass utilizing relevant temperatures and residence times in sequential drying, baking, and sintering steps. Experiments were performed with two commercially available dispersions and a simple model mixture containing a single PFAS species (6:2 fluorotelomer alcohol [6:2 FTOH]). Vapor-phase emissions were sampled and characterized by several off-line and real-time mass spectrometry techniques for targeted and non-targeted PFAS. Results indicate multiple PFAS thermal transformation products and multiple non-halogenated organic species were emitted from the exit of the high temperature third (sintering) furnace when 6:2 FTOH was the only PFAS present in the aqueous mixture. This finding supports the hypothesis that temperatures typical of these industrial furnaces may also induce chemical transformations within the fluorinated air emissions. Experiments using the two commercial fluoropolymer dispersions indicate air emissions of part-per-million by volume (ppmv) concentrations of heptafluoropropyl-1,2,2,2-tetrafluoroethyl ether (Fluoroether E1), as well as other PFAS at operationally relevant temperatures. We suspect that E1 is a direct thermal decomposition product (via decarboxylation) of 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy)propanoic acid (commonly referred to as HFPO-DA) present in the dispersions. Other thermal decomposition products, including the monomer, tetrafluoroethene, may originate from the PFAS used to stabilize the dispersion or from the polymer particles in suspension. This study represents the first researcher-built coating application simulator to report nontargeted PFAS emission characterization, real-time analyses, and the quantification of 30 volatile target PFAS.

Characterization of Gas and Particulate Phase Organic Emissions (C9-C37) from a Diesel Engine and the Effect of Abatement Devices.

Particulate and vapor phase emissions in the diluted exhaust of a light-duty diesel engine designed for Euro 5 application have been sampled. The engine was operated in three modes, and samples were collected from the exhaust without aftertreatment but also with aftertreatment by an exhaust oxidation catalyst and particle filter. The samples were analyzed by two-dimensional gas chromatography with time-of-flight mass spectral detection. The results show overall removal efficiencies for the organic compound mass by the combination of oxidation catalyst and particle filter of 50, 56, and 74% for the high-speed/high-load, low-speed/low-load, and high-speed/low-load conditions respectively. The results are clearly indicative of substantial repartitioning of the particulate and vapor components within the abatement devices and show an apparently reduced efficiency for the removal of high-molecular-weight alkanes under high-speed/high-load conditions relative to lower-molecular-weight compounds, although this may be due to alkane formation by thermocracking of other species. A notable feature is the presence of oxygenated compounds in the emissions, which are not present in the fuel. These are increased under high-speed/high-load conditions, and the results suggest the formation in the aftertreatment devices as well as in the combustion process.

Modelling of propane emissions from a tank containing a liquefied phase

During gas-phase release from the tank containing liquefied gas, the phenomenon of boiling, heat transfer from moist air to the tank, heat exchange between shell, liquid, and vapor, and mass loss can be observed. The aim of this paper is modelling the thermal response of the tank containing liquefied gas during jet emission of the vapor phase. The model takes into account heat exchange between air, tank’s shell, liquid phase, vapor phase and mass balance. The proposed model predicts: pressure inside the tank, tank’s shell temperature in part with liquid and vapor, the temperature of the liquid phase and vapor phase, and mass loss from the tank. The results of the theoretical model were compared with experimental results. An experiment based on the typical home container for LPG, containing 10 kg of propane (27 dm3 volume) was conducted. In general, the proposed model predicts well the changes in measured parameters temperatures and pressure - during vapor phase emission from a tank containing liquefied gas.

Vanadium and tungsten release from V-based selective catalytic reduction diesel aftertreatment

Vanadium-based selective catalytic reduction (V-SCR) catalysts are currently used for the reduction of nitrogen oxides (NOx) in worldwide diesel applications including Euro IV, V, and VI as well as U.S. nonroad Tier 4 Final. Although V-SCR catalysts are attractive because of their high NOx conversion, low cost, resistance to sulfur poisoning, and ability to reduce hydrocarbon emissions, there is concern that V-SCR washcoat material (e.g., vanadium and tungsten) and its derivatives may be released into the atmosphere, potentially harming human health and the environment. In this study, vanadium and tungsten release measurements are made with both a reactor- and engine-based approach in order to determine the potential release of these metals from diesel exhaust aftertreatment systems that contain a V-SCR catalyst. Results for a commercially available V-SCR reveal that both V and W release begin at 500 °C, and both reactor- and engine-based methods are capable of measuring qualitatively similar release. Emissions with the engine-based method are higher at all temperatures evaluated, likely due to this method's ability to capture particle-phase and vapor-phase emissions which become particle-bound after their evolution from the catalyst surface. Certification relevant data (NRTC and NRSC) from a nonroad engine is used to understand probable emissions from V-SCR aftertreatment architectures. Finally, results from a V-SCR catalyst formulated for improved thermal durability illustrate that it is possible to increase the maximum temperature for V-SCR catalysts. This comprehensive understanding of the temperature dependence of vanadium and tungsten volatility can be used to further analyze the full impact of diesel aftertreatment on exhaust emissions and their impact on human health and environmental toxicity.

ChemInform Abstract: Phosphorescent State of p-Fluorobenzaldehyde

Phosphorescence spectra of p-fluorobenzaldehyde have been observed in (i) the vapor phase at room temperature and in (ii) methylcyclohexane and (iii) methyl benzoate matrices at 4.2 K. From the vibrational analysis and deuteration effect it is established that the phosphorescent state is nπ* in cases i and ii while it is ππ* in case iii. A close similarity between the vapor phase emission spectra of p-fluorobenzaldehyde and benzaldehyde leads us to the conclusion that the substitution of the fluorine atom for the para hydrogen atom of benzaldehyde has little effect to the both triplet states. Several experimental data for low frequency vibrations in the excited 3nπ* state will be given by analyzing hot sequence bands of the vapor phosphorescence spectrum.

Interspecies and interregional comparisons of the chemistry of PAHs and trace elements in mosses Hylocomium splendens (Hedw.) B.S.G. and Pleurozium schreberi (Brid.) Mitt. from Poland and Alaska

Comparative biogeochemical studies performed on the same plant species in remote areas enable pinpointing interspecies and interregional differences of chemical composition. This report presents baseline concentrations of PAHs and trace elements in moss species Hylocomium splendens and Pleurozium schreberi from the Holy Cross Mountains (south-central Poland) (HCM) and Wrangell–Saint Elias National Park and Preserve (Alaska) and Denali National Park and Preserve (Alaska). Total PAH concentrations in the mosses of HCM were in the range of 473–2970 μg kg −1 (dry weight basis; DW), whereas those in the same species of Alaska were 80–3390 μg kg −1 DW. Nearly all the moss samples displayed the similar ring sequence: 3 > 4 > 5 > 6 for the PAHs. The 3 + 4 ring/total PAH ratios show statistically significant differences between HCM (0.73) and Alaska (0.91). The elevated concentrations of PAHs observed in some sampling locations of the Alaskan parks were linked to local combustion of wood, with a component of vehicle particle- and vapor-phase emissions. In HCM, the principal source of PAH emissions has been linked to residential and industrial combustion of coal and vehicle traffic. In contrast to HCM, the Alaskan mosses were distinctly elevated in most of the trace elements, bearing a signature of the underlying geology. H. splendens and P. schreberi showed diverse bioaccumulative capabilities of PAHs in all three study areas.

Speciation and quantification of vapor phases in soy biodiesel and waste cooking oil biodiesel

This study characterizes the compositions of two biodiesel vapors, soy biodiesel and waste cooking oil biodiesel, to provide a comprehensive understanding of biodiesels. Vapor phases were sampled by purging oil vapors through thermal desorption tubes which were then analyzed by the thermal desorption/GC/MS system. The results show that the compounds of biodiesel vapors can be divided into four groups. They include methyl esters (the main biodiesel components), oxygenated chemicals, alkanes and alkenes, and aromatics. The first two chemical groups are only found in biodiesel vapors, not in the diesel vapor emissions. The percentages of mean concentrations for methyl esters, oxygenated chemicals, alkanes and alkenes, and aromatics are 66.1%, 22.8%, 4.8% and 6.4%, respectively for soy biodiesel, and 35.8%, 35.9%, 27.9% and 0.3%, respectively for waste cooking oil biodiesel at a temperature of 25 ± 2 °C. These results show that biodiesels have fewer chemicals and lower concentrations in vapor phase than petroleum diesel, and the total emission rates are between one-sixteenth and one-sixth of that of diesel emission, corresponding to fuel evaporative emissions of loading losses of between 106 μg l −1 and 283 μg l −1. Although diesels generate more vapor phase emissions, biodiesels still generate considerable amount of vapor emissions, particularly the emissions from methyl esters and oxygenated chemicals. These two chemical groups are more reactive than alkanes and aromatics. Therefore, speciation and quantification of biodiesel vapor phases are important.

99/02029 Trace metal partitioning when firing pulverized coal and coal-water slurry fuel: Nodelman, I. G. et al. Prepr. Extract Abstr. ACS Natl. Meet., Am. Chem. Soc., Div. Environ. Chem., 1998, 38, (2), 169–172

Major environmental issues are now coming to the forefront in all parts of the globe with increased public awareness of the human health effects and the possible effects on our global environment. Modern control technologies, when implemented, have significantly reduced air pollution emissions that are a result of coal combustion during this century. However, the emissions have not been completely eliminated. On this basis, a study was conducted to determine the efficacy of carboxylic calcium and magnesium salts (e.g., calcium magnesium acetate or CMA, CaMg2 (CH3CO2)6) for the simultaneous removal of SO2 and NOx in oxygen-lean atmospheres. Experiments were performed in a high-temperature furnace that stimulated the post-flame environment of a coal-fired boiler by providing similar temperatures and partial pressures of SO2, NOx, CO2, and O2. When injected into a hot environment, the salts calcined and formed highly porous ‘popcorn’-like cenospheres. Residual MgO and/or CaCO3 and CaO reacted heterogeneously with SO2, and oxygen to form MgSO4 and/or CaSO4. The organic components — which can be manufactured from wastes such as sewage sludge — reduced NOx to N2 efficiently in a moderately fuel rich atmosphere. Dry-injected CMA particles at a CaS ratio of 2, residence time of 1 s and bulk equivalence ratio of 1.3 removed over 90% of SO2 and NOx at gas temperatures ≥950°C. When the furnace isothermal zone was ≤950°C, CaO was essentially inert in the furnace quenching zone, while MgO continued to sorb SO2 as the gas temperature cooled at a rate of — 130°C/s. Hence, the removal of SO2 by CMA could continue for nearly the entire residence time of emissions in the exhaust stream of a power plant. The composition of the calcined salts was used to interpret the results of a cenosphere sulfation model. The sulfation kinetics of Ca-containing calcined residues were found to be bounded by those of pure CaO and pure CaCO3. The high solubility of the carboxylic acid salts makes them excellent candidates for wet injection. Fine mists of CMA sprayed in the furnace at temperatures between 850 and 1050°C, removed 90% of SO2 at a CaS molar ratio of 1, about half of the amount used in the dry injection experiments to achieve a similar SO2 reduction. The NOx reduction chemistry was not affected by water when CMA was sprayed at a CaS ratio of 1, i.e., the same reduction efficiency was achieved as with dry injection (25–30%). Thus, while a substantial degree of success has been achieved in controlling SO2 and NOx emissions, unfortunately, the emissions that are currently unable to be controlled include vapor and particulate emissions within the respirable range. The respirable particulates encompass heavy metals, polyaromatic hydrocarbons, and volatile organics and have the ability to penetrate into the lungs. The vapor phase emissions comprise mercury, arsenic, and selenium. Most of the mercury vapor emissions are unable to be controlled by the current technologies of the electrostatic precipitator or the baghouse. Some of the potential emissions are known to be carcinogens. Therefore, new or improved current technologies for emission control are being developed in hopes of reducing the potential effects. Because previous interest for control technology was directed toward the control of acid rain precursors (sulfur dioxide and nitrogen oxides emissions), and laboratory studies revealed that the injection of calcium magnesium acetate (CMA) into the combustion chamber significantly reduces both levels of emissions, the effect of this sorbent on mercury vapor capture was investigated suing CMA ash after combustion with the gases (SO2 and NOx). Also, the effect of calcium magnesium carbonate (dolomite, CMC), currently being injected into industrial furnaces, was investigated utilizing the same combustion conditions as CMA. In addition, CMA when calcined forms cenospheres which possess thin porous walls with blowholes that enable mercury vapor and respirable particulates to penetrate into the interior of the particle. Thus, these CMA-ash cenospheres have higher porosity and surface area that provides more area for capture and reactions to occur than CMC ash. Experiments for mercury capture have demonstrated that CMA ash combusted with the gases SO2NOx provided the greatest removal (40%); CMC at the same conditions exhibited only 4% removal. Furthermore, in separate experiments using a model particulate (FeSO4), CMA ash was able to capture more of these model air particulates than the CMC ash after combustion suggesting an even further role of CMA in particulate toxin capture. Analysis of ‘spent’ CMA or CMA ‘ash’ from the laboratory furnace, which was combusted with SO2NOx revealed substantial amounts of elemental sulfur, while no elemental sulfur was present on CMA ash which was combusted in the furnace without SO2NOx. These results suggest that CMA pyrolysis serves to reduce SO2 to elemental sulfur and indicating that HgS(s) formation is feasible, thus suggesting the scavenger value of CMA in capturing mercury vapor.

99/02031 Use of coal combustion byproducts in infrastructure projects - a total benefit option: Militaru, C. and Humphrey, H. J. Proc., Annu. Meet. Air Waste Manage. Assoc., 1996, 89, ra11401, 1–12

Major environmental issues are now coming to the forefront in all parts of the globe with increased public awareness of the human health effects and the possible effects on our global environment. Modern control technologies, when implemented, have significantly reduced air pollution emissions that are a result of coal combustion during this century. However, the emissions have not been completely eliminated. On this basis, a study was conducted to determine the efficacy of carboxylic calcium and magnesium salts (e.g., calcium magnesium acetate or CMA, CaMg2 (CH3CO2)6) for the simultaneous removal of SO2 and NOx in oxygen-lean atmospheres. Experiments were performed in a high-temperature furnace that stimulated the post-flame environment of a coal-fired boiler by providing similar temperatures and partial pressures of SO2, NOx, CO2, and O2. When injected into a hot environment, the salts calcined and formed highly porous ‘popcorn’-like cenospheres. Residual MgO and/or CaCO3 and CaO reacted heterogeneously with SO2, and oxygen to form MgSO4 and/or CaSO4. The organic components — which can be manufactured from wastes such as sewage sludge — reduced NOx to N2 efficiently in a moderately fuel rich atmosphere. Dry-injected CMA particles at a CaS ratio of 2, residence time of 1 s and bulk equivalence ratio of 1.3 removed over 90% of SO2 and NOx at gas temperatures ≥950°C. When the furnace isothermal zone was ≤950°C, CaO was essentially inert in the furnace quenching zone, while MgO continued to sorb SO2 as the gas temperature cooled at a rate of — 130°C/s. Hence, the removal of SO2 by CMA could continue for nearly the entire residence time of emissions in the exhaust stream of a power plant. The composition of the calcined salts was used to interpret the results of a cenosphere sulfation model. The sulfation kinetics of Ca-containing calcined residues were found to be bounded by those of pure CaO and pure CaCO3. The high solubility of the carboxylic acid salts makes them excellent candidates for wet injection. Fine mists of CMA sprayed in the furnace at temperatures between 850 and 1050°C, removed 90% of SO2 at a CaS molar ratio of 1, about half of the amount used in the dry injection experiments to achieve a similar SO2 reduction. The NOx reduction chemistry was not affected by water when CMA was sprayed at a CaS ratio of 1, i.e., the same reduction efficiency was achieved as with dry injection (25–30%). Thus, while a substantial degree of success has been achieved in controlling SO2 and NOx emissions, unfortunately, the emissions that are currently unable to be controlled include vapor and particulate emissions within the respirable range. The respirable particulates encompass heavy metals, polyaromatic hydrocarbons, and volatile organics and have the ability to penetrate into the lungs. The vapor phase emissions comprise mercury, arsenic, and selenium. Most of the mercury vapor emissions are unable to be controlled by the current technologies of the electrostatic precipitator or the baghouse. Some of the potential emissions are known to be carcinogens. Therefore, new or improved current technologies for emission control are being developed in hopes of reducing the potential effects. Because previous interest for control technology was directed toward the control of acid rain precursors (sulfur dioxide and nitrogen oxides emissions), and laboratory studies revealed that the injection of calcium magnesium acetate (CMA) into the combustion chamber significantly reduces both levels of emissions, the effect of this sorbent on mercury vapor capture was investigated suing CMA ash after combustion with the gases (SO2 and NOx). Also, the effect of calcium magnesium carbonate (dolomite, CMC), currently being injected into industrial furnaces, was investigated utilizing the same combustion conditions as CMA. In addition, CMA when calcined forms cenospheres which possess thin porous walls with blowholes that enable mercury vapor and respirable particulates to penetrate into the interior of the particle. Thus, these CMA-ash cenospheres have higher porosity and surface area that provides more area for capture and reactions to occur than CMC ash. Experiments for mercury capture have demonstrated that CMA ash combusted with the gases SO2NOx provided the greatest removal (40%); CMC at the same conditions exhibited only 4% removal. Furthermore, in separate experiments using a model particulate (FeSO4), CMA ash was able to capture more of these model air particulates than the CMC ash after combustion suggesting an even further role of CMA in particulate toxin capture. Analysis of ‘spent’ CMA or CMA ‘ash’ from the laboratory furnace, which was combusted with SO2NOx revealed substantial amounts of elemental sulfur, while no elemental sulfur was present on CMA ash which was combusted in the furnace without SO2NOx. These results suggest that CMA pyrolysis serves to reduce SO2 to elemental sulfur and indicating that HgS(s) formation is feasible, thus suggesting the scavenger value of CMA in capturing mercury vapor.

99/02032 Commercial nuclear reactor loose part monitor setpoints: Persio, J. V. Progress in Nuclear Energy, 1999, 34, (3), 203–211

Major environmental issues are now coming to the forefront in all parts of the globe with increased public awareness of the human health effects and the possible effects on our global environment. Modern control technologies, when implemented, have significantly reduced air pollution emissions that are a result of coal combustion during this century. However, the emissions have not been completely eliminated. On this basis, a study was conducted to determine the efficacy of carboxylic calcium and magnesium salts (e.g., calcium magnesium acetate or CMA, CaMg2 (CH3CO2)6) for the simultaneous removal of SO2 and NOx in oxygen-lean atmospheres. Experiments were performed in a high-temperature furnace that stimulated the post-flame environment of a coal-fired boiler by providing similar temperatures and partial pressures of SO2, NOx, CO2, and O2. When injected into a hot environment, the salts calcined and formed highly porous ‘popcorn’-like cenospheres. Residual MgO and/or CaCO3 and CaO reacted heterogeneously with SO2, and oxygen to form MgSO4 and/or CaSO4. The organic components — which can be manufactured from wastes such as sewage sludge — reduced NOx to N2 efficiently in a moderately fuel rich atmosphere. Dry-injected CMA particles at a CaS ratio of 2, residence time of 1 s and bulk equivalence ratio of 1.3 removed over 90% of SO2 and NOx at gas temperatures ≥950°C. When the furnace isothermal zone was ≤950°C, CaO was essentially inert in the furnace quenching zone, while MgO continued to sorb SO2 as the gas temperature cooled at a rate of — 130°C/s. Hence, the removal of SO2 by CMA could continue for nearly the entire residence time of emissions in the exhaust stream of a power plant. The composition of the calcined salts was used to interpret the results of a cenosphere sulfation model. The sulfation kinetics of Ca-containing calcined residues were found to be bounded by those of pure CaO and pure CaCO3. The high solubility of the carboxylic acid salts makes them excellent candidates for wet injection. Fine mists of CMA sprayed in the furnace at temperatures between 850 and 1050°C, removed 90% of SO2 at a CaS molar ratio of 1, about half of the amount used in the dry injection experiments to achieve a similar SO2 reduction. The NOx reduction chemistry was not affected by water when CMA was sprayed at a CaS ratio of 1, i.e., the same reduction efficiency was achieved as with dry injection (25–30%). Thus, while a substantial degree of success has been achieved in controlling SO2 and NOx emissions, unfortunately, the emissions that are currently unable to be controlled include vapor and particulate emissions within the respirable range. The respirable particulates encompass heavy metals, polyaromatic hydrocarbons, and volatile organics and have the ability to penetrate into the lungs. The vapor phase emissions comprise mercury, arsenic, and selenium. Most of the mercury vapor emissions are unable to be controlled by the current technologies of the electrostatic precipitator or the baghouse. Some of the potential emissions are known to be carcinogens. Therefore, new or improved current technologies for emission control are being developed in hopes of reducing the potential effects. Because previous interest for control technology was directed toward the control of acid rain precursors (sulfur dioxide and nitrogen oxides emissions), and laboratory studies revealed that the injection of calcium magnesium acetate (CMA) into the combustion chamber significantly reduces both levels of emissions, the effect of this sorbent on mercury vapor capture was investigated suing CMA ash after combustion with the gases (SO2 and NOx). Also, the effect of calcium magnesium carbonate (dolomite, CMC), currently being injected into industrial furnaces, was investigated utilizing the same combustion conditions as CMA. In addition, CMA when calcined forms cenospheres which possess thin porous walls with blowholes that enable mercury vapor and respirable particulates to penetrate into the interior of the particle. Thus, these CMA-ash cenospheres have higher porosity and surface area that provides more area for capture and reactions to occur than CMC ash. Experiments for mercury capture have demonstrated that CMA ash combusted with the gases SO2NOx provided the greatest removal (40%); CMC at the same conditions exhibited only 4% removal. Furthermore, in separate experiments using a model particulate (FeSO4), CMA ash was able to capture more of these model air particulates than the CMC ash after combustion suggesting an even further role of CMA in particulate toxin capture. Analysis of ‘spent’ CMA or CMA ‘ash’ from the laboratory furnace, which was combusted with SO2NOx revealed substantial amounts of elemental sulfur, while no elemental sulfur was present on CMA ash which was combusted in the furnace without SO2NOx. These results suggest that CMA pyrolysis serves to reduce SO2 to elemental sulfur and indicating that HgS(s) formation is feasible, thus suggesting the scavenger value of CMA in capturing mercury vapor.

Modeling the Reduction of Vapor Phase Emissions from Surface Soils Due to Soil Matrix Effects: Porosity/Tortuosity Concepts

ABSTRACT A major route for transport of volatile organic compounds within porous media is vapor phase diffusion. The diffusion rate through a porous medium is less than that through free-air due to the decreased cross-sectional area available for gas movement and the increased path length due to pore tortuosity. Numerous empirical expressions have been published that relate the diffusion coefficient in porous media to the diffusion coefficient in free-air (unobstructed gas phase). Published measurements of relative diffusivity and air-filled porosity were combined into a database. Empirical expressions available in the literature, including the popular Millington-Quirk equation, were evaluated along with a fourth-degree polynomial expression developed by the authors to determine the best type of equation to predict relative diffusivity as a function of air-filled porosity over the domain of values for porosity ranging from 0.071 to 1 for different types of materials. Mean square deviations were used as the statistical test to compare equations. The polynomial expression developed in this project produced a significantly different effective diffusion coefficient (1.3 x 10-6 m2/sec) compared to values of 9.2 x 10-6 m2/sec and 3.1 x 10-6 m2/ sec predicted by forms of the Millington-Quirk equation for a specific case.

Control of air toxin particulate and vapor emissions after coal combustion utilizing calcium magnesium acetate

Control of air toxin particulate and vapor emissions after coal combustion utilizing calcium magnesium acetate

Phosphorescent State of p-Fluorobenzaldehyde

Abstract Phosphorescence spectra of p-fluorobenzaldehyde have been observed in (i) the vapor phase at room temperature and in (ii) methylcyclohexane and (iii) methyl benzoate matrices at 4.2 K. From the vibrational analysis and deuteration effect it is established that the phosphorescent state is nπ* in cases i and ii while it is ππ* in case iii. A close similarity between the vapor phase emission spectra of p-fluorobenzaldehyde and benzaldehyde leads us to the conclusion that the substitution of the fluorine atom for the para hydrogen atom of benzaldehyde has little effect to the both triplet states. Several experimental data for low frequency vibrations in the excited 3nπ* state will be given by analyzing hot sequence bands of the vapor phosphorescence spectrum.

Chemical and Toxicological Characterization of Residential Oil Burner Emissions: II. Mutagenic, Tumorigenic, and Potential Teratogenic Activity

Extracts of effluents from a modern residential oil burner have been evaluated in several toxicological assay systems. Bacterial mutagens were detected in extracts from both the particulate and vapor phase emissions. Effluents from continuous operation were an order of magnitude less mutagenic than those from cyclic (5 min on, 10 min off) operations. No difference in the yield of bacterial mutagens per gram of fuel burned was found between cyclic operation under low and moderate sooting conditions. On the basis of elution behavior from alumina it appeared that the bacterial mutagens collected from high sooting effluents were more polar than those from low sooting effluent. An extract that was mutagenic in bacteria did not induce a significant increase in mutation frequency to human lymphoblasts. No evidence of tumorigenicity was observed in a limited number of newborn mice after IP injection of effluent extract when compared to historical control data. Putative nonmutagenic teratogens were detected in effluent using an attachment inhibition assay. The level of these agents was reduced in effluents from continuous oil burner operation.

Chemical and toxicological characterization of residential oil burner emissions: II. Mutagenic, tumorigenic, and potential teratogenic activity.

Extracts of effluents from a modern residential oil burner have been evaluated in several toxicological assay systems. Bacterial mutagens were detected in extracts from both the particulate and vapor phase emissions. Effluents from continuous operation were an order of magnitude less mutagenic than those from cyclic (5 min on, 10 min off) operations. No difference in the yield of bacterial mutagens per gram of fuel burned was found between cyclic operation under low and moderate sooting conditions. On the basis of elution behavior from alumina it appeared that the bacterial mutagens collected from high sooting effluents were more polar than those from low sooting effluent. An extract that was mutagenic in bacteria did not induce a significant increase in mutation frequency to human lymphoblasts. No evidence of tumorigenicity was observed in a limited number of newborn mice after IP injection of effluent extract when compared to historical control data. Putative nonmutagenic teratogens were detected in effluent using an attachment inhibition assay. The level of these agents was reduced in effluents from continuous oil burner operation.

Spectrally separated fluorescence emissions for diesel fuel droplets and vapor

Spectrally separated fluorescence emissions from liquid and vapor diesel fuel can be obtained by adding an exciplex-forming molecule to the fuel. The exciplex emission dominates the condensed phase emission, while the monomer emission dominates the vapor phase emission. In particular with the naphthalene/tetramethyl-p-phenylene diamine system, the liquid and vapor phase emissions peak at 470 and 380 nm, respectively. Results for droplets at 110 and 250°C are presented.

Models of mechanisms for the vapor phase emission of hazardous chemicals from landfills

Quantities of hazardous chemicals have been placed in sanitary landfills in conjunction with solid waste. This paper presents three vapor phase transport mechanisms: molecular diffusion, bio-gas convection, and barometric pressure pumping. These mechanisms are incorporated into a dynamic model that simulates the emission flux rate of chemicals, as a function of landfill and environmental variables. The simulation model is driven by time-varying atmospheric pressure fluctuations. Darcy's law is used to simulate gas movement through the landfill cap material to and from the landfill cells. With all mechanisms operative, a rate of 290 g benzene/m 2 d was obtained from the model using benzene as a test chemical. Atmospheric pressure fluctuations pump toxic vapors and gases from the storage cells of hazardous waste landfills to the air above. This pumping enhances the vapor phase molecular diffusion process. The calculated benzene flux rate with diffusion and atmosphere pumping was 13 g/m 2 d. Uncertainties and limitations of the model are considered which include: vapor and gas circulation in and between cells, adsorption onto solids and multi-cell landfills. The model presented is a practical tool for initial evaluation studies of volatile chemical emissions from landfills and provides a basis upon which to construct more realistic simulation models.