Cette étude s’inscrit dans le cadre de l’amélioration des connaissances liées à l’évaporation d’aérosols liquides semi-volatils collectés sur des filtres à fibres. Le phénomène d’évaporation d’aérosols collectés sur médias fibreux induit des problèmes de sécurité avec notamment une surexposition des salariés aux vapeurs, à l’aval des systèmes généraux de filtration de l’air. De plus, lors des contrôles des concentrations atmosphériques des aérosols, l’évaporation induit une sous-estimation de la phase particulaire de l’aérosol prélevé qui est problématique en termes de prévention de l’exposition. L’objectif de ces travaux a donc été de produire de nombreux résultats expérimentaux afin, d’une part, de compléter les rares présents dans la littérature et, d’autre part, d’améliorer les modèles théoriques développés précédemment. Deux approches expérimentales ont été menées afin d’identifier le processus d’évaporation d’un aérosol collecté. La première, nommée approche globale, permet de suivre l’évaporation de l’aérosol par la quantification des vapeurs à l’aval du filtre, au cours du temps. La seconde, nommée approche microscopique, étudie l’évaporation de gouttes collectées sur les fibres d’une fibre à l’échelle microscopique. Les deux approches réalisées lors de ces travaux s’accordent sur le fait que l’évaporation d’un aérosol liquide semi-volatil ne peut être modélisée par les modèles proposés par la littérature. Des hypothèses ont été avancées afin d’expliquer la divergence de cinétique d’évaporation entre la théorie et les expérimentations / This study falls within the scope of improving knowledge concerning evaporation of semi-volatile liquid aerosols collected on fibrous filters. Under these conditions, the aerosol evaporation phenomenon causes problems of safety, in particular over-exposure of employees to vapours downstream of general air filtering systems. Furthermore, when controlling aerosol atmospheric concentrations, evaporation results in under-estimation of the sampled aerosol particle phase and this is clearly problematic in exposure prevention terms. The aim of this work was therefore to record a large number of experimental data, both to make up for their scarcity in the literature and to improve previously developed theoretical models. Two experimental approaches were implemented to identify the evaporation process for a collected aerosol. The first, termed the global approach, allowed us to monitor aerosol evaporation by measuring vapour quantity downstream of the filter with respect to time. The second, microscopic, approach considers evaporation of droplets collected on the filter fibres on a microscopic scale. The two approaches implemented during this research lead to agreement on the fact that evaporation of a liquid semi-volatile aerosol cannot be satisfactorily represented by the theoretical models proposed in the literature. Hypotheses are advanced to explain the divergence in evaporation kinetics between theoretical and experimental work

Volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs) constitute important classes of indoor contaminants. Emissions of VOCs and SVOCs from myriad building materials and consumer products cause high indoor concentrations with health risks that may be orders-of-magnitude greater than outdoors. The need to control VOC and SVOC emissions from interior materials and thereby reduce indoor concentrations is made more urgent by the prevailing drive for air-tight, energy efficient buildings. To develop low-emission products, emission rates are usually measured in emission chambers. However, there are three significant problems associated with chamber tests: (1) VOC emissions testing procedures of individual laboratories are frequently subject to error and uncertainty; (2) SVOC emissions testing in chambers is extremely difficult and time-consuming, and also subject to error and uncertainty; and (3) chamber tests provide little insight into the mechanisms controlling emissions. This research aimed to solve these problems by developing reference materials for VOC and SVOC emissions testing. Formaldehyde was studied separately from other VOCs because of its unusual properties. Emission mechanisms, and the related modeling approaches for predicting emissions, were investigated by reviewing the literature and performing chamber studies. Based on the internally controlled VOC and formaldehyde emission mechanisms, diffusion-controlled reference materials, which mimic real sources, were created for VOCs and formaldehyde. Approaches for developing externally controlled reference materials for SVOC emissions testing were also explored. Appropriate mechanistic models can predict the true emission rates of the reference materials and therefore provide reference values to validate emissions testing results and certify procedures of individual laboratories. The potential of a solid phase microextraction (SPME) method was also evaluated and found to be a promising technique that can be used in chamber tests to simplify and improve sampling and analytical procedures. This research elucidates the mass-transfer mechanisms of VOC and SVOC emissions and provides practical approaches for developing reference materials for emissions testing. The fundamental understanding and methodological advances will enhance indoor air quality science, improve the emissions testing industry, and provide a sound basis on which to develop standards and regulations. / Ph. D.

The investigation of the atmospheric fate and transport of semi-volatile organic compounds (SOCs) often requires the sampling of large volumes of air (>100 m3) in a relatively short period of time. Conventionally high-volume pumps are not suitable for remote areas without access to reliable network power. We have developed a flow through sampler for such situations. It consists of a horizontally-oriented flow-tube, that can collect gaseous and particle-bound SOCs from large volumes of air by turning into the wind and having the wind blow through a porous sampling medium such as polyurethane foam. Through both indoor and outdoor experiments, we quantified its air sampling rate (through battery operated anemometers inside and outside of the flow tube), its sampling efficiency (by theoretical plate number analysis of the break-though curves for PCBs, PAHs, OCPs and PBDEs), and its accuracy (by comparison of concentrations, time trends, temperature dependences and isomer ratios with those obtained by conventional high-volume sampling) under conditions of constant and variable meteorological conditions (wind speed, temperature). The flow-through sampler was deployed to monitor SOC concentrations at a remote Chinese research station located close to Nam Co Lake, Tibet. During the campaign, fifteen 1 month-long samples were taken, corresponding to sample volumes between 5,000 and 20,000 m3. Despite those large sample volumes, only HCB and HCHs experienced break-through, but application of frontal chromatograph theory allows the estimation of breakthrough-corrected air concentrations even for those relatively volatile SOCs. The pesticide levels at Nam Co are generally very low. Most pesticides had higher levels during summer, resulting in a strong temperature dependence. This is correlated with air mass origin across the Himalayas in the Gangetic plains of India and Bangladesh. The flow through sampler constitutes a feasible method for reliably and quantitatively collecting SOCs from large air volumes.

Submitted by Márcio Justi Laranja (marciojusti21@gmail.com) on 2018-05-28T15:19:36Z No. of bitstreams: 1 dissertação(versão final).pdf: 4313795 bytes, checksum: fef2f9c53ba336958ef95fc671df0d72 (MD5) / Approved for entry into archive by Paula Torres Monteiro da Torres (paulatms@sjrp.unesp.br) on 2018-05-28T16:41:46Z (GMT) No. of bitstreams: 1 laranja_mj_me_sjrp_int.pdf: 4313795 bytes, checksum: fef2f9c53ba336958ef95fc671df0d72 (MD5) / Made available in DSpace on 2018-05-28T16:41:46Z (GMT). No. of bitstreams: 1 laranja_mj_me_sjrp_int.pdf: 4313795 bytes, checksum: fef2f9c53ba336958ef95fc671df0d72 (MD5) Previous issue date: 2018-05-18 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A carbonização hidrotérmica (CHT) é um processo de conversão termoquímica, capaz de usar uma biomassa úmida como matéria-prima e convertê-la em um produto sólido rico em carbono orgânico, denominado carvão hidrotérmico, passível de aplicação ao solo. No processo também é obtida como produto uma fração líquida contendo uma variedade de compostos orgânicos de interesse comercial e/ou tóxicos ao ambiente, denominada água de processo. Nesse trabalho, bagaço de cana e/ou vinhaça foram submetidos ao processo de CHT, sob diferentes condições reacionais. Assim, foram avaliados os efeitos do tipo de biomassa e das variáveis do processo (tempo, temperatura e porcentagem de adição de ácido fosfórico) sobre a composição do carvão hidrotérmico e da água de processo, em relação aos compostos orgânicos semivoláteis (SVOC) e voláteis (VOC). Para isso, foi realizada a extração de SVOC no carvão hidrotérmico e na água de processo utilizando extração ultrassônica e extração líquido-líquido, respectivamente. Já os VOC foram extraídos com o método do headspace associado à microextração em fase sólida (HS-SPME). Os compostos orgânicos foram identificados por cromatografia em fase gasosa acoplada à espectrometria de massas (GC-MS). Os principais SVOC identificados no carvão hidrotérmico foram fenóis, ácidos carboxílicos, cetonas e compostos nitrogenados, indicando que este material contém funções orgânicas importantes e incorporação de nitrogênio, sendo estas características desejáveis para uma possível aplicação em solo. O tipo de biomassa carbonizada, a temperatura e adição de ácido fosfórico (H3PO4) durante o processo CHT mostraram ter grande influência nos SVOC identificados tanto no carvão hidrotérmico quanto na água de processo, enquanto o efeito do tempo não foi significativo. Condições de temperatura elevada e maior porcentagem de H3PO4 promoveram, respectivamente, maior aromatização e funcionalização do carvão hidrotérmico. Além disso, a adição de ácido na CHT provocou a diminuição de compostos fenólicos e furânicos e aumento de ácidos carboxílicos e cetonas na água de processo. Os principais VOC identificados foram aldeídos, cetonas, fenóis, furanos e compostos nitrogenados. O aumento da temperatura promoveu a degradação dos aldeídos e aumento de cetonas e fenóis no carvão hidrotérmico. Já a adição de H3PO4 afetou a degradação dos compostos nitrogenados no carvão hidrotérmico e na água de processo. / Hydrothermal carbonization (HTC) is a thermochemical conversion process, able to use a moisture biomass as raw material and convert it into a solid product rich in organic carbon, called hydrochar, amenable to application to the soil. In the process, a liquid fraction is also obtained as product containing a variety of organic compounds, of commercial interest and/or toxic to the environment, called process water. In this work, sugarcane bagasse and vinasse were submitted to the HTC process, in different reaction conditions. Thus, the effects of the biomass type and the process variables were evaluated (time, temperature and percentage of phosphoric acid addition) on the composition of hydrochar and process water in the case of semi-volatile organic compounds (SVOC) and volatile organic compounds (VOC). For this, the SVOC extraction from the hydrochar and the process water were performed using ultrasonic extraction and liquid-liquid extraction, respectively. The VOC extraction was performed by headspace-solid phase microextraction (HS-SPME) method. The identification of organic compounds was performed by gas chromatography-mass spectrometry (GC-MS). The SVOC were identified, with mainly phenols, carboxylic acids, ketones and nitrogen compounds obtained, indicating that the hydrochar produced contains important organic functions and nitrogen incorporation into the material, desirable characteristics for a soil application. The pattern of SVOC obtained both in hydrochar and in process water showed great dependence on the type of carbonized biomass and with the carbonization temperature and phosphoric acid addition, while the effect of time was not significant. High temperature and higher H3PO4 percentage conditions promoted, respectively, greater aromatization and functionalization of the hydrochar. Furthermore, the addition of acid in HTC caused the decrease of phenolic compounds and furans and increased carboxylic acids and ketones in process water. The VOC were identified, with mainly aldehydes, ketones, phenols, furans and nitrogen compounds. The increase in temperature promoted degradation of aldehydes and increase of ketones and phenols in the hydrochar. On the other hand, the H3PO4 addiction affected the degradation of the nitrogen compounds in the hydrochar and process water.

The investigation of the atmospheric fate and transport of semi-volatile organic compounds (SOCs) often requires the sampling of large volumes of air (>100 m3) in a relatively short period of time. Conventionally high-volume pumps are not suitable for remote areas without access to reliable network power. We have developed a flow through sampler for such situations. It consists of a horizontally-oriented flow-tube, that can collect gaseous and particle-bound SOCs from large volumes of air by turning into the wind and having the wind blow through a porous sampling medium such as polyurethane foam. Through both indoor and outdoor experiments, we quantified its air sampling rate (through battery operated anemometers inside and outside of the flow tube), its sampling efficiency (by theoretical plate number analysis of the break-though curves for PCBs, PAHs, OCPs and PBDEs), and its accuracy (by comparison of concentrations, time trends, temperature dependences and isomer ratios with those obtained by conventional high-volume sampling) under conditions of constant and variable meteorological conditions (wind speed, temperature). The flow-through sampler was deployed to monitor SOC concentrations at a remote Chinese research station located close to Nam Co Lake, Tibet. During the campaign, fifteen 1 month-long samples were taken, corresponding to sample volumes between 5,000 and 20,000 m3. Despite those large sample volumes, only HCB and HCHs experienced break-through, but application of frontal chromatograph theory allows the estimation of breakthrough-corrected air concentrations even for those relatively volatile SOCs. The pesticide levels at Nam Co are generally very low. Most pesticides had higher levels during summer, resulting in a strong temperature dependence. This is correlated with air mass origin across the Himalayas in the Gangetic plains of India and Bangladesh. The flow through sampler constitutes a feasible method for reliably and quantitatively collecting SOCs from large air volumes.

No description available.

The promulgation of revised standards for atmospheric fine particles (PM2.5) by the US EPA has sparked renewed interest in the ability to accurately measure and characterize suspended atmospheric particulate matter. Semi-volatile material (SVM), consisting of ammonium nitrate and semi-volatile organic material (SVOM), is not accurately measured by EPA accepted methods such as the Federal reference method (FRM) or Tapered Element Oscillating Microbalance (TEOM). However, SVM is often a major fraction of urban aerosols. Recent advances in atmospheric sampling instrumentation allowed for the semi-continuous characterization of urban PM2.5, including SVM. The Filter Dynamic Measurement System (FDMS) was shown to measure total PM2.5 mass including semi-volatile species. Validation of the FDMS was performed by comparison with the particle concentrator-Brigham Young University organic sampling system (PC-BOSS) and the real-time total ambient mass sampler (RAMS). Semi-continuous ambient particulate concentrations of sulfate, nitrate and ammonium ion were measured by a newly developed Dionex instrument which was field tested and validated for the first time in Fresno, CA. Either a modified Sunset Laboratory carbon monitor, collocated with a conventional Sunset carbon monitor employing a common inlet, or the newly developed dual-oven Sunset monitor allowed for the semi-continuous determination of both nonvolatile and semi-volatile organic material. This was the first attempt to characterize both nonvolatile and semi-volatile fractions of an urban aerosol in a semi-continuous manner using all semi-continuous instruments. A suite of instruments for semi-continuous PM2.5 monitoring was recommended including, an R&P FDMS for the measurement of PM2.5 mass, a dual-oven Sunset monitor for the measurement of nonvolatile and semi-volatile carbonaceous species, and a Dionex GP-IC for the measurement of inorganic species. A TEOM monitor is also recommended to measure nonvolatile PM2.5 mass. Using these instruments, semi-continuous mass closure was obtained for the first time during a study conducted in Riverside, CA. The advantage of using semi-continuous sampler data in the application of source apportionment was elucidated. Local aerosols are often impacted by short-term pollution episodes that cannot be temporally resolved using integrated samplers. One-h averaged data applied to source apportionment models was shown to increase the power of the model to predict sources, both primary and secondary, that exhibit diurnal short-term episodes.

Modern indoor environments contain a vast array of contaminating sources. Emissions from these sources produce contaminant concentrations that are substantially higher indoors than outside. Because we spend most of our time indoors, exposure to indoor pollutants may be orders-of-magnitude greater than that experienced outdoors. Phthalate esters have been recognized as major indoor pollutants. They are mainly used as plasticizers to enhance the flexibility of polyvinylchloride (PVC) products, as well as in humectants, emollients, and antifoaming agents. Phthalates are found in a wide range of consumer products including floor and wall coverings, car interior trim, floor tiles, gloves, footwear, insulation on wiring, and artificial leather. Because these phthalate additives are not chemically bound to the polymer matrix, slow emission from the products to the surrounding air or other media usually occurs. Biomonitoring data suggest that over 75% of the U.S. population is exposed to phthalates. The ubiquitous exposure to phthalates is of concern because toxicological investigations have demonstrated considerable adverse health effects of phthalates and their metabolites. Studies have shown that exposure to phthalates results in profound and irreversible changes in the development of the reproductive tract, especially in males, raising the possibility that phthalate exposures could be the leading cause of reproductive disorders in humans. In addition, effects such as increases in prenatal mortality, reduced growth and birth weight, skeletal, visceral, and external malformations are possibly associated with phthalate exposure. Epidemiologic studies in children also show associations between phthalate exposure in the home and the risk of asthma and allergies. Given the ubiquitous nature of phthalates in the environment and the potential for adverse human health impacts, there is a critical need to understand indoor emissions of phthalates and to identify the most important sources and pathways of exposure. In this study, a model that integrates the fundamental mechanisms governing emissions of semi-volatile organic compounds (SVOCs) from polymeric materials and their subsequent interaction with indoor surfaces and airborne particles was developed. The emissions model is consistent with analogous mechanistic models that predict emission of volatile organic compounds (VOCs) from building materials. Reasonable agreement between model predictions and gas-phase di-2-ethylhexyl phthalate (DEHP) concentrations was achieved for data collected in a previously published experimental study that measured emissions of DEHP from vinyl flooring in two very different chambers. The analysis showed that while emissions of highly volatile VOCs are subject to “internal“ control (through the material-phase diffusion coefficient), emissions of the very low volatility SVOCs are subject to “external“– control (through partitioning into the gas phase, the convective mass transfer coefficient, and adsorption onto interior surfaces). Because of the difficulties associated with sampling and analysis of SVOCs, only a few chamber studies quantifying their emissions from building materials and consumer products are available. To more rigorously validate the SVOCs emission model and more completely understand the mechanisms governing the release of phthalate from polymeric building materials, the emission of DEHP from vinyl flooring was studied for up to 140 days in a specially-designed stainless steel chamber. In the duplicate chamber study, the gas-phase concentration in the chamber increased slowly and reached a steady state level of 0.9 µg/m3 after 30 days. By increasing the area of vinyl flooring and decreasing that of the stainless steel surface in the chamber, the time to reach steady state was significantly reduced, compared to the previous study (1 month vs. 5 months). The adsorption isotherm of DEHP on the interior stainless steel chamber surface was explicitly measured using two different methods (solvent extraction and thermal desorption). Strong adsorption of DEHP onto the stainless steel surface was observed and found to follow a simple linear relationship. In addition, parameters measured in the experiments were then applied in the fundamental SVOCs emission model. Good agreement was obtained between the predictions of the model and the gas-phase DEHP chamber concentrations, without resorting to fitting of model parameters. These chamber studies have shown that the tendency of SVOCs to adsorb strongly to interior surfaces has a very strong influence on the emission rate. Compared to the experimental chamber systems, however, the real indoor environment has many other types of surface that will adsorb phthalates to different extents. The emission rate measured in a test chamber may therefore be quite different to the emission rate from the same material in the indoor environment. For this reason, both a two-room model and a more representative three-compartment model were developed successively to estimate the emission rate of DEHP from vinyl flooring, the evolving gas-phase and adsorbed surface concentrations, and human exposures (via inhalation, dermal absorption and oral ingestion of dust) in a realistic indoor environment. Adsorption isotherms for phthalates and plasticizers on interior surfaces, such as carpet, wood, dust and human skin, were derived from previous field and laboratory studies. A subsequent sensitivity analysis revealed that the vinyl flooring source characteristics, as well as mass-transfer coefficients and ventilation rates, are important variables influencing the steady-state DEHP concentration and resulting exposures. A simple uncertainty analysis suggested that residential exposure to DEHP originating from vinyl flooring may fall somewhere between about 5 µg/kg/d and 180 µg/kg/d. The roughly 40-fold range in exposure reveals the inherent difficulty in using biomonitoring results to identify specific sources of exposure in the general population. This research represents the first attempt to explicitly elucidate the fundamental mechanisms governing the release of phthalates from polymeric building materials as well as their subsequent interaction with interior surfaces. The mechanistic models developed can most likely be extended to predict concentration and exposure arising from other sources of phthalates, other sources of other semi-volatile organic compounds (such as biocides and flame retardants), as well as emissions into other environmental media (food, water, saliva, and even blood). The results will be of value to architects, governments, manufacturers, and engineers who wish to specify low-emitting green materials for healthy buildings. It will permit health professionals to identify and control health risks associated with many of the SVOCs used in indoor materials and consumer products in a relatively inexpensive way. / Ph. D.

If sufficiently persistent, semi-volatile organic contaminants (SVOCs) can travel long distances through the atmosphere from their points of release and become concentrated in cold, remote regions. As air is sampled for SVOCs to establish both their presence and the success of emission reduction efforts, it becomes helpful to determine sampling site proximity to sources and the origin of the sampled air masses. Comparing three increasingly sophisticated methods for quantifying source proximity of sampling locations, it was judged necessary to account for the actual history of the sampled air through construction of an airshed, especially if wind is highly directional and population distribution is very non-uniform. The airshed concept was improved upon by introducing a ‘geodesic’ grid of equally spaced cells, rather than a simple latitude/longitude grid, to avoid distortion near Earth’s poles and to allow for the comparison of airshed shapes. Assuming that a perfectly round airshed reveals no information about sources allows the significance of each cell of an airshed to be judged based on its departure from roundness. Combining air-mass histories with a 2 year-long series of SVOC air concentrations at Little Fox Lake in Canada’s Yukon Territory did not identify distinct source regions for most analytes, although γ-hexachlorocyclohexane appears to originate broadly in north-eastern Russia and/or Alaska. Based on this remoteness from sources, the site is judged to be well suited to monitor changes in the hemispheric background concentrations of SVOCs. A model-based exploration revealed wet-gaseous deposition as the dominant process responsible for cold-trapping SVOCs in mountain soils. Such cold trapping is particularly effective if precipitation rate increases with altitude and if temperature differences along the mountain are large. Considerable sensitivity of the modeled extent of cold-trapping to parameters as diverse as scale, mean temperature, atmospheric particle concentration and time relative to emission maxima is consistent with the wide variety of observed enrichment behaviour. Concentration gradients of polycyclic aromatic hydrocarbons and polychlorinated biphenyls in air and soil measured on four Western Canadian mountains with variable distance from sources revealed source proximity as the main driver of concentrations at both the whole-mountain scale and along individual mountain transects.

If sufficiently persistent, semi-volatile organic contaminants (SVOCs) can travel long distances through the atmosphere from their points of release and become concentrated in cold, remote regions. As air is sampled for SVOCs to establish both their presence and the success of emission reduction efforts, it becomes helpful to determine sampling site proximity to sources and the origin of the sampled air masses. Comparing three increasingly sophisticated methods for quantifying source proximity of sampling locations, it was judged necessary to account for the actual history of the sampled air through construction of an airshed, especially if wind is highly directional and population distribution is very non-uniform. The airshed concept was improved upon by introducing a ‘geodesic’ grid of equally spaced cells, rather than a simple latitude/longitude grid, to avoid distortion near Earth’s poles and to allow for the comparison of airshed shapes. Assuming that a perfectly round airshed reveals no information about sources allows the significance of each cell of an airshed to be judged based on its departure from roundness. Combining air-mass histories with a 2 year-long series of SVOC air concentrations at Little Fox Lake in Canada’s Yukon Territory did not identify distinct source regions for most analytes, although γ-hexachlorocyclohexane appears to originate broadly in north-eastern Russia and/or Alaska. Based on this remoteness from sources, the site is judged to be well suited to monitor changes in the hemispheric background concentrations of SVOCs. A model-based exploration revealed wet-gaseous deposition as the dominant process responsible for cold-trapping SVOCs in mountain soils. Such cold trapping is particularly effective if precipitation rate increases with altitude and if temperature differences along the mountain are large. Considerable sensitivity of the modeled extent of cold-trapping to parameters as diverse as scale, mean temperature, atmospheric particle concentration and time relative to emission maxima is consistent with the wide variety of observed enrichment behaviour. Concentration gradients of polycyclic aromatic hydrocarbons and polychlorinated biphenyls in air and soil measured on four Western Canadian mountains with variable distance from sources revealed source proximity as the main driver of concentrations at both the whole-mountain scale and along individual mountain transects.