Crystallographically solids with well defined crystal structures are normally assumed to be highly ordered. However, it is not uncommon to find considerable degree of disorder amongst many of these crystalline substances. Disorder among crystalline substances often arise from the rotational motion which leads to the well known class of plastic crystalline substances. Typically, globular molecules such as methane, carbon tetrachloride or adamantane exhibit plastic crystalline phase with significant amount of orientational disorder. In many other substances, disorder arises from torsional motion as in the case of biphenyl, p- or o-terphenyls, stilbene or azobenzenes. In case of molecules with flexible segment, such as alkanes or surfactants, motion of the terminal methyl group or terminal ethyl group is responsible for the observed disorder. Chapter 1 discusses various aspects of disorder in crystals. A new pressure induced solid phase of biphenyl is reported at room temperature. Isothermal-isobaric ensemble variable shape simulation cell Monte Carlo calculations are reported on biphenyl at 300K as a function of pressure between 0-4 GPa. The potential proposed by Williams for inter-molecular and Benkert-Heine-Simmons(BHS) for intramolecular interactions have been employed. Different properties indicating changes in the crystal structure, molecular structure, distributions of inter- and intra-molecular energy are reported as a function of pressure. With increase in pressure beyond 0.8 GPa, the dihedral angle distribution undergoes a change from a bimodal to an unimodal distribution. The changes in IR and Raman spectra across the transition computed from ab initio calculations are in agreement with the experimental measurements. It is shown that at pressures larger than 0.8 GPa, competition between inter-molecular interactions with intra-molecular terms v/z., conjugation energy and the ortho-ortho repulsion favors a planar biphenyl due to better packing and consequently a predominant inter-molecular term. The exact value of the transition pressure will depend on the accuracy of the inter- and intra-molecular potentials employed here. p-terphenyl has been modeled at 300K and atmospheric pressure with different potential models. Modified Fihppini parameters for mtermolecular interactions and BHS potential for inter-ring torsion predict the structure of p-terphenyl reasonably well. Pressure variation calculations are carried out with this combination of inter- and intra-molecular potential. The structure as a function of pressure upto 5 GPa has been compared with experimental structure provided by Puschnig et al. The transformation of functional form of the potential energy curve (associated with the inter-ring flipping) from W-shaped to [/-shaped form as a function of pressure has been observed. This is in excellent agreement with previous studies of polyphenyls including biphenyl and p-hexaphenyl. The complete planarization of molecules occurs when the pressure range is 1.0 GPa-1.5 GPa. Molecular simulation of solid stilbene in the isothermal-isobaric ensemble with variable shape simulation are reported. Structure has been characterized by means of lattice parameters and radial distribution functions. Simulations show existence of pedal-like motion at higher temperatures in agreement with the recent X-ray diffraction measurements by Ogawa and co-workers and several others previously. Difference in energy between the major and minor conformers, barrier to conformational change at both the crystallographic sites have been calculated. Temperature dependence of the equilibrium constant between the two conformers as well as the rate of conversion between the con-formers at the two sites have been calculated. These are in agreement with the recent analysis by Harada and Ogawa of non-equilibrium states obtained by rapid cooling of stilbene. Volume and total intermolecular energy suggest existence of two transitions in agreement with previous Raman phonon spectroscopic and calorimetric studies. They seem to be associated with change from order to disorder at the two sites. Ab initio calculations coupled with simulations suggest that the disorder accounts for only a small part of the observed shortening in ethylene bond ength. A Monte Carlo simulation with variable shape simulation cell has been carried out on stilbene. The study attempts to investigate the disorder at various pressures upto 4 GPa. It is seen that the population of minor conformers at sites 1 and 2 decrease with increase in pressure. Population of minor conformers at site 2 decreases to zero by 1.5 GPa. In contrast, the population of minor conformers at site 1 remains finite for the runs reported here. It is seen that the population of minor conformers at site 1 is higher than at site 2 at room temperature which is to be expected on the basis of the activation energies. Associated changes in the unit cell as well as molecular conformation are discussed. Isothermal-isobaric ensemble Monte Carlo simulation of adamantane has been earned out with variable shape simulation cell. Low temperature crystalline phase and the room temperature plastic crystalline phases have been studied employing the Williams potential. We show that at room temperature, the plastic crystalline phase transforms to the crystalline phase on increase in pressure. Further, we show that this is the same phase as the low temperature ordered tetragonal phase of adamantane. The high pressure ordered phase appears to be characterized by a slightly larger shift of the first peak towards lower value of r in C-C, C-H and H-H rdfs as compared to the low temperature tetragonal phase. Co-existence curve between the crystalline and plastic crystalline phase has been obtained approximately upto a pressure of 4 GPa. We investigate the equation of state, variation of lattice parameters and the distortion of molecular geometry of low temperature phase of adamantane upto 26 GPa pressure. A rigid and a flexible model of adamantane have been studied using variable shape simulation within the isothermal-isobaric ensemble. Including six low frequency modes obtained from density functional theory carried out on a single-molecule has incorporated the flexibility. These calculations used Becke 3-parameter method and Lee-Yang-Parr electron correlation functional with 6-31G(d) basis set. The simulated equation of state and variation of c/a ratio as a function of pressure are compared with the experimental results. The results are in good agreement with high pressure experiments. Nature of distortion in molecular geometry obtained from the calculation are also in good agreement with the experiment.

This thesis describes the investigation of three aspects of the formation of secondary organic aerosol (SOA): * Aerosol formation from mixed precursors * Global modelling of SOA formation * Modelling of dynamics of SOA formation based on empirical data collected from smog chamber experiments. The formation and growth processes of secondary organic aerosol were investigated using smog chamber experimentation and modelling techniques to gain a better understanding of the application of SOA yield values in modelling both SOA mass and dynamics. Published SOA yields from a range of volatile organic compounds (VOCs) are used to model SOA mass on a local, regional or global scale, based on the assumption that the SOA yield of a mixture is the sum of the yields of the components. Experimental investigations into SOA yield from mixtures of VOC revealed potential uncertainties that would result from applying these yields to systems containing multiple VOCs. SOA formation in systems of toluene or m-xylene, compared with systems of these VOCs and propene, have shown that the introduction of propene (which has a zero SOA yield) to smog chamber photo-oxidations of toluene or m-xylene delays the formation and suppresses the overall yield of SOA from 450 to 90 µg m-3 ppm-1 for the toluene system and from 325 to 125 µg m-3 ppm-1 for the mvxylene system compared with systems of individual species without propene. The SOA partitioning yield data also indicates that partitioning of species to existing aerosol is suppressed in the mixed systems. Gas-phase modelling of these experiments showed that potential SOA species were expected to be formed sooner due to the increased system reactivity provided by propene. The observed delay in SOA nucleation, similar consumption rates of toluene and m-xylene in both the single and mixed systems and the gas-phase modelling results suggest that the addition of propene to hydrocarbon SOA systems modifies the gas-phase chemistry leading to the formation of potential SOA species from toluene and m-xylene. This result calls into question the bulk and partitioning yield values that have been published for pure substances as well as the validity of applying individual VOC yields to VOC mixture. Application of SOA yields to the global scale provides estimates of annual global SOA formation, global contributions from various VOCs and regional SOA distributions. Two SOA modules, using bulk and partitioning yield methods, were added to a global atmospheric chemical transport model, MOZART-2. The bulk yield method, representing the maximum possible global SOA burden, gave an annual production of 24.5 Tg of SOA, which is slightly lower than previous estimates (30 - 270 Tg yr-1). The partitioning method, which gives a more realistic estimate of SOA formation, produced 15.3 Tg yr-1; the biogenic fraction (13.6 Tg yr-1) compares to a previous estimate of biogenic SOA of 18.5 Tg yr-1 and 2.5 to 44 Tg yr- 1 using the partitioning method. Anthropogenic SOA contributions of 1.1 Tg yr-1 from MOZART-2 compared to recent estimates of 0.05 -2.62 Tg yr-1. SOA production was found to be dependent on oxidant availability and VOC emissions in South America and Asia. The partitioning method produced significantly less SOA due to limited availability of OC. Thepartitioning method also produced a peak SOA concentration of 10 µg m-3 over South America in September and showed that SOA is at maximum production for most of the year in Asia and Europe. The two SOA formation methods also provides data to analyse the restrictions to SOA formation in particular regions, based on the maximum amount of SOA able to form (bulk yield method) and the more realistic partitioning estimate from the same region. Limitations to SOA formation in a particular region can be attributed to deficiencies in OC availability or VOC oxidant concentrations. Comparisons to limited observational and modelled data suggest that the MOZART-2 SOA model provides a good representation of global averaged SOA. SOA mass concentrations, predicted by models such as MOZART-2, can be used in part to model the dynamics of an SOA population (e.g. size of particles, number concentrations etc.). Aerosol properties such as size and number concentration can then be used to estimate their effect on climate and health. The explicit representation of the processes that affect aerosol dynamics, such as nucleation, condensation, evaporation and coagulation can be complex and use significant computational resources. Simplification of the discrete coagulation equation and empirical coagulation coefficients for continuum and non-continuum regime diffusion kinetics provided a simplified method of coagulation capable of predicting the evolution of inert sodium chloride aerosol in chamber experiments. A variable coagulation coefficient (linked to the mean particle number concentration of each experiment) was developed. This method is an empirical surrogate for the standard coefficient corrections applied to Brownian based diffusion in the continuum regime to account for the different kinetic effects within the transition and free molecular diffusion regimes. This method removes the need for calculating individual coefficients for each particle interaction. Estimates of modeluncertainty show that within uncertainty limits the model provides a good representation of experimental data. Correlation and index of agreement (IOA) calculations revealed good statistical agreement between modelled and experimental. Some experiments showed degrees of coagulation under prediction using the variable coefficient technique. Investigations into the effect of aerosol type and size, temperature and humidity may be necessary to refine the variable coefficient calculation technique. The model showed little sensitivity to model time step and is capable of high resolution representation of the aerosol. Mass concentration is conserved within the model whereas some error due to numerical diffusion within the number concentrations results from the bin sectioning technique used. The simplicity of this sectioning method over other methods and the minimal effect of numerical diffusion establishes a simplified method of modelling relative to the high resolution of the aerosol distribution the model achieves. It is suggested that the efficiency improvements introduced by the approaches used in developing this model provide an efficient ultra-fine coagulation modelling for atmospheric models. A semi-empirical model for SOA dynamics (SPLAT) incorporating coagulation, nucleation, condensation and evaporation was developed. The aim of the model and the development process was to predict, with high resolution and minimal computational expense, the formation and growth of SOA given a SOA mass input as a function of time. The average size distribution profile from chamber experimental data was used as part of the nucleation module. This technique provided an alternative method of representing the particle distribution compared to those models that assume a single diameter of nucleated particle or a fixed log-normal mode for the entire evolution of SOA. All SPLAT simulations assume organic nucleation events within the experiments modelled, although it is stilluncertain whether they occur in the atmosphere. The modelled nucleation events have produced a single nucleation burst, a result of immediate domination of condensation as soon as nucleation occurs. This deficiency is likely to be a result of the assumption of free molecular diffusion for condensation. The rate of condensation, calculated at every time step, is based on the aerosol size distributed surface area and the particle-size-dependent saturation mass concentrations. The SPLAT coagulation module was a version of the model developed in Chapter 6. Comparisons between experimental and modelled data showed good agreement. These comparisons revealed the shortcomings in the nucleation module while a statistical analysis of the modelled and experimental data has shown SPLAT to be effective in modelling a range of SOA systems. The complexity introduced in modelling aerosol dynamics in high resolution is offset in SPLAT by efficiency improvements due to the insensitivity of the model to time step size and simplified methods of bin sectioning, nucleation, coagulation, condensation and evaporation. Published SOA yields can be applied to predict SOA mass at local, regional or global scales. Although previously unreported uncertainties in these yields have been shown to exist, the MOZART-2 global chemical transport model has shown that SOA mass concentration can be predicted with reasonable quality, considering the scale of the model and limited observational data. These global scale SOA mass predictions can be used purely for global burden and occurrence, or as the input for modelling the dynamics of an aerosol population, which is significant for estimating an aerosol population's effect on climate change and health. SOA mass concentrations from chamber experiments were used as input to a SOA dynamics model. This model (SPLAT) then predicted the evolution of particle number concentrations and size within these experiments based on this mass input. Application of the dynamics model to the output of the MOZART-2 model could then provide a comprehensive global scale SOA modelling package.

A geração de resíduos sólidos é inerente ao desenvolvimento humano. O concreto armado é um dos materiais mais utilizados pelo homem e tem o cimento Portland como seu principal constituinte, o qual é produzido pela moagem de clínquer e gesso. O clínquer pode ser definido como um mineral artificial, obtido a partir das reações físico-químicas de calcário, argila e corretivos a altas temperaturas, em forno rotativo industrial, mediante a queima de combustíveis fósseis. No início da década de 70 foram realizadas as primeiras experiências de substituição de combustíveis fósseis por resíduos industriais nos Estados Unidos e países europeus, através da técnica denominada co-processamento, resultando na manufatura de um produto ao mesmo tempo em que os resíduos eram eliminados. O co-processamento se baseia na recuperação da energia disponível nos resíduos, substituindo parte daquela fornecida pelos combustíveis tradicionais ou na substituição de matérias-primas por resíduos com características químicas semelhantes àquelas normalmente empregadas na produção do clínquer. No estado de São Paulo as primeiras iniciativas para a utilização de resíduos industriais em fornos de clínquer ocorreram no início da década de 90. A partir de 1997 os órgãos ambientais de alguns estados brasileiros normatizaram procedimentos de licenciamento da atividade que foi, posteriormente, uniformizada por norma em âmbito federal. No ano de 1995 a Companhia de Cimento Ribeirão Grande/SP, Brasil, iniciou os procedimentos visando a substituição parcial dos combustíveis utilizados nos fornos rotativos por uma mistura de resíduos industriais. No período de 1995 a 2002 foram realizadas campanhas de amostragens em chaminés para avaliação das emissões atmosféricas dos dois fornos de produção de clínquer. A análise dos resultados obtidos associada às demais informações disponíveis de monitoramento das características das matérias-primas e combustíveis utilizados, bem como dos produtos finais, clínquer e cimento, não evidenciou alterações significativas nos níveis de emissões atmosféricas, sobretudo de material particulado e óxidos de enxofre, que pudessem ser associadas à utilização dos resíduos. Foram confirmadas as baixas emissões de inorgânicos e evidenciado o papel representado pelos resíduos no aporte dessas substâncias no sistema-forno, concluindo-se que esse aporte pode ser tão ou mais importante pela via da alimentação da farinha, cujos teores estão associados às características das jazidas minerais utilizadas. Foi também confirmada a alta eficiência do sistema-forno na destruição e remoção dos compostos orgânicos perigosos alimentados durante os testes de queima. / The production of industrial residues in inherent to the human development. The cement concrete is one of the most used material, manly the type portland cement, which is constituted by grinding clinker and gypsum together. Clinker can be defined as an artificial mineral obtained by applying physico-chemical reactions, at very high temperatures, to an appropriated mixture of limestone, clay, and some other materials in a rotating industrial kiln wich burns fossil fuels. In the early 1970 decade occurred the first experiences substituting fossil fuels by organic residues in USA and Europe through a technique named co-processing that results the production of certain manufacture while eliminates residues. Co-processing is based in the recovery of thermal energy and/or the mass of some constituents from some residues, with the same chemical characteristics of normal sources of energy, then economizing fuels and mass constituents and making better use of residues, otherwise useless and environmentally polluters. In the state of São Paulo this practice began in early 1990 decade and by 1997 it was started the standardization of the rules for its use in some units of the federation. Later this activity was regulated by nationally approved standard rules. In 1995 the industry Companhia de Cimento Ribeirão Grande (CCRG), a cement plant located in the city of Ribeirão Grande, São Paulo state, Brazil, started procedures searching the partial substitution of the normal fuels by a mixture of industrial residues in its two rotating kilns. The gaseous emissions from the chimneys of these two clinker kilns were studied from 1995 to 2002 about the use of residues as part of the fuel. Analyses of the final results associated with other informations concerning to the quality of raw minerals, fuels and products did not show significant alterations in atmospheric emissions, mainly for particulate material and sulfur oxides, related with the use of residues. The emissions of inorganic continued to be low and not significantly altered by the presence of residues. It was possible to conclude that the alterations in inorganic emissions depend more from the quality of the raw minerals feed in the kilns, which is more difficult to control, than from the presence of residues being burn with the fuel. It was shown a high efficiency in the destruction of dangerous organic compounds feed in the cement kilns, under test conditions.

Abstract The releases of chlorinated volatile organic compounds (CVOCs) are controlled by strict regulations setting high demands for the abatement systems. Low temperature catalytic oxidation is a viable technology to economically destroy these often refractory emissions. Catalysts applied in the oxidation of CVOCs should be highly active and selective but also maintain a high resistance towards deactivation. In this study, a total of 33 different γ-Al2O3 containing metallic monoliths were studied in dichloromethane (DCM) and 25 of them in perchloroethylene (PCE) oxidation. The active compounds used were Pt, Pd, Rh or V2O5 alone or as mixtures. The catalysts were divided into three different testing sets: industrial, CVOC and research catalysts. ICP-OES, physisorption, chemisorption, XRD, UV-vis DRS, isotopic oxygen exchange, IC, NH3-TPD, H2-TPR and FESEM-EDS were used to characterise the catalysts. Screening of the industrial catalysts revealed that the addition of V2O5 improved the performance of the catalyst. DCM abatement was easily affected by the addition of VOC or water, but the effect on the PCE oxidation was only minor. Based on these screening tests, a set of CVOC catalysts were developed and installed into an industrial incinerator. The comparison between the laboratory and industrial scale studies showed that DCM oxidation in an industrial incinerator could be predicted relatively well. Instead, PCE was always seen to be oxidised far better in an industrial unit indicating that the transient oxidation conditions are beneficial for the PCE oxidation. Before starting the experiments with research catalysts, the water feed was optimised to 1.5 wt.%. Besides enhancing the HCl yields, water improved the DCM and PCE conversions. In the absence of oxygen, i.e. during destructive adsorption, the presence of water was seen to have an even more pronounced effect on the HCl formation and on the catalysts’ stability. In the DCM oxidation, the addition of the active compound on the catalyst support improved the selectivity, while the enhancing effect on the DCM conversion was only small. The high acidity together with the increased reducibility was seen to lead to an active catalyst. Among the research catalysts Pt/Al2O3 was the most active in the DCM oxidation. With PCE the addition of the active compound proved to be very beneficial also for the PCE conversion. Now Pt and Pd supported on Al2O3-CeO2 were the most active. The enhanced reducibility was seen to be the key feature of the catalyst in PCE oxidation. / Tiivistelmä Klooratuille orgaanisille hiilivedyille (CVOC) on asetettu tiukat päästörajoitukset niiden haitallisten vaikutusten takia. Tästä johtuen myös puhdistusmenetelmien tulee olla tehokkaita. Katalyyttinen puhdistus on teknologia, jolla nämä usein vaikeasti käsiteltävät yhdisteet voidaan taloudellisesti tuhota. Käytettävien katalyyttien tulee olla aktiivisia ja selektiivisiä sekä hyvin kestäviä. Tässä työssä tutkittiin yhteensä 33 erilaista γ-Al2O3-pohjaista hapetuskatalyyttiä metyleenikloridin (DCM) käsittelyssä, niistä 25 testattiin myös perkloorietyleenin (PCE) hapetuksessa. Aktiivisina metalleina katalyyteissä käytettiin platinaa, palladiumia, rhodiumia ja vanadiinia yksin tai seoksina. Katalyytit jaettiin kolmeen ryhmään: teolliset-, CVOC- ja tutkimuskatalyytit. Aktiivisuuskokeiden lisäksi katalyyttejä karakterisoitiin ICP-OES-, fysiorptio-, kemisorptio-, XRD-, UV-vis DRS-, isotooppivaihto-, IC-, NH3-TPD-, H2-TPR- ja FESEM-EDS-pintatutkimusmenetelmillä. Koetulokset osoittivat, että vanadiini paransi teollisuuskatalyyttien aktiivisuutta ja selektiivisyyttä. VOC-yhdisteen tai veden lisäys paransi DCM:n hapettumista, mutta PCE:n hapettumiseen niillä ei ollut vaikutusta. Testien perusteella kehitettiin CVOC-katalyytit, jotka asennettiin teolliseen polttolaitokseen. Laboratoriossa ja teollisuudessa tehdyissä testeissä havaittiin, että DCM:n hapettuminen oli laboratoriokokeiden perusteella ennustettavissa. Sen sijaan PCE hapettui teollisuudessa aina paljon paremmin kuin laboratorio-olosuhteissa. Tämä osoittaa, että muuttuvat hapettumisolosuhteet vaikuttivat positiivisesti PCE:n hapettumiseen. Veden määrä syöttövirrassa optimoitiin 1,5 %:iin ennen tutkimuskatalyyttien testausta. Selektiivisyyden lisäksi vesi paransi DCM:n ja PCE:n konversiota. Hapettomissa olosuhteissa, ts. tuhoavien adsorptiokokeiden aikana, vesi paransi reaktion selektiivisyyttä HCl:ksi ja CO2:ksi vielä entisestään. Tämän lisäksi vesi lisäsi katalyytin stabiilisuutta. DCM:n hapetuksessa aktiivisen metallin lisäys paransi selektiivisyyttä, mutta sen sijaan vaikutus DCM:n konversioon oli hyvin pieni. Tulokset osoittivat, että aktiivisella DCM:n hapetuskatalyytillä tulee olla korkea happamuus ja hyvä pelkistyvyys. Pt/Al2O3 oli testatuista tutkimuskatalyyteistä aktiivisin. PCE:n hapetuksessa aktiivisen metallin lisäys paransi selektiivisyyden lisäksi huomattavasti myös konversiota. Katalyytin lisääntyneen pelkistymiskyvyn todettiin olevan keskeisin ominaisuus PCE:n hapettumisessa. Pt/Al2O3-CeO2 ja Pd/Al2O3-CeO2 olivat tutkimuskatalyyteistä aktiivisimpia.

Il est reconnu que le benzène, le toluène, l’éthylbenzène et les isomères du xylène, composés organiques volatils (COVs) communément désignés BTEX, produisent des effets nocifs sur la santé humaine et sur les végétaux dépendamment de la durée et des niveaux d’exposition. Le benzène en particulier est classé cancérogène et une exposition à des concentrations supérieures à 64 g/m3 de benzène peut être fatale en 5–10 minutes. Par conséquent, la mesure en temps réel des BTEX dans l’air ambiant est essentielle pour détecter rapidement un danger associé à leur émission dans l’air et pour estimer les risques potentiels pour les êtres vivants et pour l’environnement. Dans cette thèse, une méthode d’analyse en temps réel des BTEX dans l’air ambiant a été développée et validée. La méthode est basée sur la technique d’échantillonnage direct de l’air couplée avec la spectrométrie de masse en tandem utilisant une source d’ionisation chimique à pression atmosphérique (APCI-MS/MS directe). La validation analytique a démontré la sensibilité (limite de détection LDM 1–2 μg/m3), la précision (coefficient de variation CV < 10%), l’exactitude (exactitude > 95%) et la sélectivité de la méthode. Des échantillons d’air ambiant provenant d’un site d’enfouissement de déchets industriels et de divers garages d’entretien automobile ont été analysés par la méthode développée. La comparaison des résultats avec ceux obtenus par la technique de chromatographie gazeuse on-line couplée avec un détecteur à ionisation de flamme (GC-FID) a donné des résultats similaires. La capacité de la méthode pour l’évaluation rapide des risques potentiels associés à une exposition aux BTEX a été prouvée à travers une étude de terrain avec analyse de risque pour la santé des travailleurs dans trois garages d’entretien automobile et par des expériences sous atmosphères simulées. Les concentrations mesurées dans l’air ambiant des garages étaient de 8,9–25 µg/m3 pour le benzène, 119–1156 µg/m3 pour le toluène, 9–70 µg/m3 pour l’éthylbenzène et 45–347 µg/m3 pour les xylènes. Une dose quotidienne environnementale totale entre 1,46 10-3 et 2,52 10-3 mg/kg/jour a été déterminée pour le benzène. Le risque de cancer lié à l’exposition environnementale totale au benzène estimé pour les travailleurs étudiés se situait entre 1,1 10-5 et 1,8 10-5. Une nouvelle méthode APCI-MS/MS a été également développée et validée pour l’analyse directe de l’octaméthylcyclotétrasiloxane (D4) et le décaméthylcyclopentasiloxane (D5) dans l’air et les biogaz. Le D4 et le D5 sont des siloxanes cycliques volatils largement utilisés comme solvants dans les processus industriels et les produits de consommation à la place des COVs précurseurs d’ozone troposphérique tels que les BTEX. Leur présence ubiquitaire dans les échantillons d’air ambiant, due à l’utilisation massive, suscite un besoin d’études de toxicité. De telles études requièrent des analyses qualitatives et quantitatives de traces de ces composés. Par ailleurs, la présence de traces de ces substances dans un biogaz entrave son utilisation comme source d’énergie renouvelable en causant des dommages coûteux à l’équipement. L’analyse des siloxanes dans un biogaz s’avère donc essentielle pour déterminer si le biogaz nécessite une purification avant son utilisation pour la production d’énergie. La méthode développée dans cette étude possède une bonne sensibilité (LDM 4–6 μg/m3), une bonne précision (CV < 10%), une bonne exactitude (> 93%) et une grande sélectivité. Il a été également démontré qu’en utilisant cette méthode avec l’hexaméthyl-d18-disiloxane comme étalon interne, la détection et la quantification du D4 et du D5 dans des échantillons réels de biogaz peuvent être accomplies avec une meilleure sensibilité (LDM ~ 2 μg/m3), une grande précision (CV < 5%) et une grande exactitude (> 97%). Une variété d’échantillons de biogaz prélevés au site d’enfouissement sanitaire du Complexe Environnemental de Saint-Michel à Montréal a été analysée avec succès par cette nouvelle méthode. Les concentrations mesurées étaient de 131–1275 µg/m3 pour le D4 et 250–6226 µg/m3 pour le D5. Ces résultats représentent les premières données rapportées dans la littérature sur la concentration des siloxanes D4 et D5 dans les biogaz d’enfouissement en fonction de l’âge des déchets. / It is known that benzene, toluene, ethylbenzene and xylene isomers, volatile organic compounds (VOCs) commonly called BTEX, have toxic health effects on humans and plants depending on duration and levels of exposure. Benzene in particular is classified carcinogenic, and exposure to benzene at concentrations above 64 g/m3 can be fatal within 5–10 minutes. Therefore, real-time monitoring of BTEX in ambient air is essential for the early warning detection associated with their release and in estimating the potential exposure risks to living beings and the environment. In this thesis, a real-time analysis method for BTEX in ambient air was developed and validated. The method is based on the direct-air sampling technique coupled with tandem mass spectrometry using atmospheric pressure chemical ionization (direct APCI-MS/MS). Validation of the method has shown that it is sensitive (limit of detection LOD 1–2 μg/m3), precise (relative standard deviation RSD < 10%), accurate (accuracy > 95%) and selective. Ambient air samples from an industrial waste landfill site and various automobile repair shops were analyzed by the developed method. Comparison of results with those obtained by online gas chromatography coupled with a flame ionization detector (GC-FID) technique exhibited similar results. The capacity of the method for the fast evaluation of potential risks associated with an exposure to BTEX has been demonstrated through a field study with health risk assessment for workers at three automobile repair shops and through experiments under simulated atmospheres. Concentrations measured in the ambient air of the garages were in the ranges of 8.9–25 µg/m3 for benzene, 119–1156 µg/m3 for toluene, 9–70 µg/m3 for ethylbenzene, and 45–347 µg/m3 for xylenes. A total environmental daily dose of 1.46 10-3–2.52 10-3 mg/kg/day was determined for benzene. The estimated cancer risk due to the total environmental exposure to benzene was between 1.1 10-5 and 1.8 10-5 for the workers studied. A novel APCI-MS/MS method was also developed and validated for the direct analysis of octamethylcyclotetrasiloxane (D4) and decamethylcyclopentasiloxane (D5) in air and biogases. D4 and D5 are cyclic volatile siloxanes widely used in industrial processes and consumer products as replacement solvents for the tropospheric ozone forming VOCs, such as BTEX. Their ubiquitous presence in ambient air samples, due to the growing consumption, raises the need for toxicity studies which require qualitative and quantitative trace analysis of these compounds. Furthermore, the presence of trace amounts of these substances in a biogas hampers its use as a source of renewable energy by causing expensive damages to the equipment. Thus, siloxane analysis of the biogas is essential in determining if purification is needed before the use for energy production. The method developed in this study for these aims has good sensitivity (LOD 4–6 μg/m3), good precision (RSD < 10%), good accuracy (> 93%) and high selectivity. It was also shown that by using this method with hexamethyl-d18-disiloxane as an internal standard, detection and quantification of D4 and D5 in real biogas samples can be done with a better sensitivity (LOD ~ 2 μg/m3), high precision (RSD < 5%), and high accuracy (> 97%). Various biogas samples collected from the landfill site of the Complexe Environnemental de Saint-Michel in Montreal have been successfully analyzed by this new method. Concentrations measured were in the ranges of 131–1275 µg/m3 for D4 and 250–6226 µg/m3 for D5. These results represent the first primary-literature-reported data on siloxanes D4 and D5 contents of landfill-derived biogases as a function of the refuse age.

Il est reconnu que le benzène, le toluène, l’éthylbenzène et les isomères du xylène, composés organiques volatils (COVs) communément désignés BTEX, produisent des effets nocifs sur la santé humaine et sur les végétaux dépendamment de la durée et des niveaux d’exposition. Le benzène en particulier est classé cancérogène et une exposition à des concentrations supérieures à 64 g/m3 de benzène peut être fatale en 5–10 minutes. Par conséquent, la mesure en temps réel des BTEX dans l’air ambiant est essentielle pour détecter rapidement un danger associé à leur émission dans l’air et pour estimer les risques potentiels pour les êtres vivants et pour l’environnement. Dans cette thèse, une méthode d’analyse en temps réel des BTEX dans l’air ambiant a été développée et validée. La méthode est basée sur la technique d’échantillonnage direct de l’air couplée avec la spectrométrie de masse en tandem utilisant une source d’ionisation chimique à pression atmosphérique (APCI-MS/MS directe). La validation analytique a démontré la sensibilité (limite de détection LDM 1–2 μg/m3), la précision (coefficient de variation CV < 10%), l’exactitude (exactitude > 95%) et la sélectivité de la méthode. Des échantillons d’air ambiant provenant d’un site d’enfouissement de déchets industriels et de divers garages d’entretien automobile ont été analysés par la méthode développée. La comparaison des résultats avec ceux obtenus par la technique de chromatographie gazeuse on-line couplée avec un détecteur à ionisation de flamme (GC-FID) a donné des résultats similaires. La capacité de la méthode pour l’évaluation rapide des risques potentiels associés à une exposition aux BTEX a été prouvée à travers une étude de terrain avec analyse de risque pour la santé des travailleurs dans trois garages d’entretien automobile et par des expériences sous atmosphères simulées. Les concentrations mesurées dans l’air ambiant des garages étaient de 8,9–25 µg/m3 pour le benzène, 119–1156 µg/m3 pour le toluène, 9–70 µg/m3 pour l’éthylbenzène et 45–347 µg/m3 pour les xylènes. Une dose quotidienne environnementale totale entre 1,46 10-3 et 2,52 10-3 mg/kg/jour a été déterminée pour le benzène. Le risque de cancer lié à l’exposition environnementale totale au benzène estimé pour les travailleurs étudiés se situait entre 1,1 10-5 et 1,8 10-5. Une nouvelle méthode APCI-MS/MS a été également développée et validée pour l’analyse directe de l’octaméthylcyclotétrasiloxane (D4) et le décaméthylcyclopentasiloxane (D5) dans l’air et les biogaz. Le D4 et le D5 sont des siloxanes cycliques volatils largement utilisés comme solvants dans les processus industriels et les produits de consommation à la place des COVs précurseurs d’ozone troposphérique tels que les BTEX. Leur présence ubiquitaire dans les échantillons d’air ambiant, due à l’utilisation massive, suscite un besoin d’études de toxicité. De telles études requièrent des analyses qualitatives et quantitatives de traces de ces composés. Par ailleurs, la présence de traces de ces substances dans un biogaz entrave son utilisation comme source d’énergie renouvelable en causant des dommages coûteux à l’équipement. L’analyse des siloxanes dans un biogaz s’avère donc essentielle pour déterminer si le biogaz nécessite une purification avant son utilisation pour la production d’énergie. La méthode développée dans cette étude possède une bonne sensibilité (LDM 4–6 μg/m3), une bonne précision (CV < 10%), une bonne exactitude (> 93%) et une grande sélectivité. Il a été également démontré qu’en utilisant cette méthode avec l’hexaméthyl-d18-disiloxane comme étalon interne, la détection et la quantification du D4 et du D5 dans des échantillons réels de biogaz peuvent être accomplies avec une meilleure sensibilité (LDM ~ 2 μg/m3), une grande précision (CV < 5%) et une grande exactitude (> 97%). Une variété d’échantillons de biogaz prélevés au site d’enfouissement sanitaire du Complexe Environnemental de Saint-Michel à Montréal a été analysée avec succès par cette nouvelle méthode. Les concentrations mesurées étaient de 131–1275 µg/m3 pour le D4 et 250–6226 µg/m3 pour le D5. Ces résultats représentent les premières données rapportées dans la littérature sur la concentration des siloxanes D4 et D5 dans les biogaz d’enfouissement en fonction de l’âge des déchets. / It is known that benzene, toluene, ethylbenzene and xylene isomers, volatile organic compounds (VOCs) commonly called BTEX, have toxic health effects on humans and plants depending on duration and levels of exposure. Benzene in particular is classified carcinogenic, and exposure to benzene at concentrations above 64 g/m3 can be fatal within 5–10 minutes. Therefore, real-time monitoring of BTEX in ambient air is essential for the early warning detection associated with their release and in estimating the potential exposure risks to living beings and the environment. In this thesis, a real-time analysis method for BTEX in ambient air was developed and validated. The method is based on the direct-air sampling technique coupled with tandem mass spectrometry using atmospheric pressure chemical ionization (direct APCI-MS/MS). Validation of the method has shown that it is sensitive (limit of detection LOD 1–2 μg/m3), precise (relative standard deviation RSD < 10%), accurate (accuracy > 95%) and selective. Ambient air samples from an industrial waste landfill site and various automobile repair shops were analyzed by the developed method. Comparison of results with those obtained by online gas chromatography coupled with a flame ionization detector (GC-FID) technique exhibited similar results. The capacity of the method for the fast evaluation of potential risks associated with an exposure to BTEX has been demonstrated through a field study with health risk assessment for workers at three automobile repair shops and through experiments under simulated atmospheres. Concentrations measured in the ambient air of the garages were in the ranges of 8.9–25 µg/m3 for benzene, 119–1156 µg/m3 for toluene, 9–70 µg/m3 for ethylbenzene, and 45–347 µg/m3 for xylenes. A total environmental daily dose of 1.46 10-3–2.52 10-3 mg/kg/day was determined for benzene. The estimated cancer risk due to the total environmental exposure to benzene was between 1.1 10-5 and 1.8 10-5 for the workers studied. A novel APCI-MS/MS method was also developed and validated for the direct analysis of octamethylcyclotetrasiloxane (D4) and decamethylcyclopentasiloxane (D5) in air and biogases. D4 and D5 are cyclic volatile siloxanes widely used in industrial processes and consumer products as replacement solvents for the tropospheric ozone forming VOCs, such as BTEX. Their ubiquitous presence in ambient air samples, due to the growing consumption, raises the need for toxicity studies which require qualitative and quantitative trace analysis of these compounds. Furthermore, the presence of trace amounts of these substances in a biogas hampers its use as a source of renewable energy by causing expensive damages to the equipment. Thus, siloxane analysis of the biogas is essential in determining if purification is needed before the use for energy production. The method developed in this study for these aims has good sensitivity (LOD 4–6 μg/m3), good precision (RSD < 10%), good accuracy (> 93%) and high selectivity. It was also shown that by using this method with hexamethyl-d18-disiloxane as an internal standard, detection and quantification of D4 and D5 in real biogas samples can be done with a better sensitivity (LOD ~ 2 μg/m3), high precision (RSD < 5%), and high accuracy (> 97%). Various biogas samples collected from the landfill site of the Complexe Environnemental de Saint-Michel in Montreal have been successfully analyzed by this new method. Concentrations measured were in the ranges of 131–1275 µg/m3 for D4 and 250–6226 µg/m3 for D5. These results represent the first primary-literature-reported data on siloxanes D4 and D5 contents of landfill-derived biogases as a function of the refuse age.

The use of pheromone-based or semiochemical lures and devices for the detection of insect pest population and monitoring in agriculture is a common practice. In many countries the use of these devices is exempt from registration requirements based on regulatory thresholds set by the relevant authorities, however, not in South Africa. The question arises whether the pheromones or semiochemicals dispensed through such devices, influence the naturally occurring compounds observed and whether a concern of toxicity and ecotoxicity is justified. A tomato field was selected in a commercial growing area of South Africa and a novel five-component lure, T.V. PheroLure®, was identified from a local manufacturer, Insect Science (Pty) Ltd. The T.V. PheroLure® consists of a Volatile Organic Compound (VOC) blend which is placed in a polyethylene bulb. Tomato VOCs were collected before, during and after the application of the T.V. PheroLure® which was used in combination with a yellow bucket funnel trap. The VOCs were collected at different heights (0 cm, 30 cm and 60 cm) of the tomato plants, from planting until harvest (22 weeks) and surrounding tomato fields without the T.V. PheroLure®. The results obtained indicated that: (i) the T.V. PheroLure® had no significant influence on the natural VOCs observed in the tomato field and (ii) that the height of sampling had no influence on VOCs observed. This study also indicated that apart from a slight increased contribution of limonene, there was no significant influence observed from the T.V. PheroLure® compounds on the natural background VOCs found in the tomato field. Therefore, it could be argued that the natural phenology of the plant has a greater influence on the VOCs observed than T.V. PheroLure® and that the concern of toxicity and ecotoxicity is unjustified when using these devices for monitoring purposes only. / Environmental Sciences / M. Sc. (Environmental Science)

Volatile Organic Compounds (VOCs) are commonly used as indicators of an organism's health, among other factors. Traditionally, gas chromatographs (GC) are used to classify these but are prohibitively expensive and impractical for field use. This thesis outlines the motivations, design, construction, and characterization of a portable GC. This proof-of-concept uses off-the-shelf components to show that the production of a device is feasible. It was able to successfully generate carrier gas from the surrounding air via filtration by activated carbon fiber filters. It was also able to reliably produce distinguishable peaks for acetone and hexane at retention times that were reasonable for a prototype system. With some modifications, this system has the strong potential for long-term implementation in the field.

In this research, a proton exchange membrane fuel cell (PEMFC) sensor was investigated for specific detection of volatile organic compounds (VOCs) for point-of-care (POC) diagnosis of the physiological conditions of humans. A PEMFC is an electrochemical transducer that converts chemical energy into electrical energy. A Redox reaction takes place at its electrodes whereas the volatile biomolecules (e.g. ethanol) are oxidized at the anode and ambient oxygen is reduced at the cathode. The compounds which were the focus of this investigation were ethanol (C2H5OH) and isoflurane (C3H2ClF5O), but theoretically, the sensor is not limited to only those VOCs given proper calibration. Detection in biosensing, which needs to be carried out in a controlled system, becomes complex in a multivariate environment. Major limitations of all types of biosensors would include poor selectivity, drifting, overlapping, and degradation of signals. Specific detection of VOCs in multi-dimensional environments is also a challenge in fuel cell sensing. Humidity, temperature, and the presence of other analytes interfere with the functionality of the fuel cell and provide false readings. Hence, accurate and precise quantification of VOC(s) and calibration are the major challenges when using PEMFC biosensor. To resolve this problem, a statistical model was derived for the calibration of PEMFC employing multivariate analysis, such as the “Principal Component Regression (PCR)” method for the sensing of VOC(s). PCR can correlate larger data sets and provides an accurate fitting between a known and an unknown data set. PCR improves calibration for multivariate conditions as compared to the overlapping signals obtained when using linear (univariate) regression models. Results show that this biosensor investigated has a 75% accuracy improvement over the commercial alcohol breathalyzer used in this study when detecting ethanol. When detecting isoflurane, this sensor has an average deviation in the steady-state response of ~14.29% from the gold-standard infrared spectroscopy system used in hospital operating theaters. The significance of this research lies in its versatility in dealing with the existing challenge of the accuracy and precision of the calibration of the PEMFC sensor. Also, this research may improve the diagnosis of several diseases through the detection of concerned biomarkers.

Indiana University-Purdue University Indianapolis (IUPUI) / The characterization of the nutrients nitrogen, phosphorus and carbon (NPC) export to streams during storms is an integral part of understanding processes affecting water quality. Despite the fact that excessive levels of these nutrients in the Mississippi River basin adversely affects water quality in the Gulf of Mexico, little research has been conducted on NPC dynamics during storms on larger (>20 km2) agriculturally dominated Midwestern watersheds. This project examined the storm export of nitrate, ammonium, total phosphorus, and dissolved organic carbon (DOC) in the upper Eagle Creek Watershed (UECW) (274 km2) in Central Indiana, USA. Water samples were collected during five winter and spring storms in 2007 and 2008 on the rising and falling limb of the hydrograph, in order to characterize NPC dynamics during storm events. Stream discharge and precipitation was monitored continuously, and major cations were used to examine changes in source water over the duration of the storm and assist in the determination of potential flowpaths. DOC, total P, and TKN (Total Kjeldahl Nitrogen) tended to peak with discharge, while nitrate usually exhibited a slight lag and peaked on the receding limb. Total phosphorus, NH3-, TKN, and DOC appear to be delivered to the stream primarily by overland flow. NO3--N appear to be delivered by a combination of tile drain and macropore flow. Overall UECW displayed smoother nutrient export patterns than smaller previously studied watersheds in the area suggesting that scale may influence nutrient export dynamics. Further research is underway on a 3000 km2 watershed in the area to further examine the role scale may play in nutrient export patterns.