Dissertations / Theses on the topic 'VOC (Volatile organic compounds)'

The central aim of this thesis is to support the efforts to counteract certain environmental problems caused by emissions of volatile organic compounds. The purpose of this work was (1) to develop a method to establish the amount of emitted substances from dryers, (2) to determine the effect of drying medium temperature and end moisture content of the processed material on emissions of monoterpenes and other hydrocarbons, (3) to examine the emissions of monoterpenes during production of pellets, and (4) to examine the natural emissions from forests with an eye to implications for modelling. The measurement method (1) resolves the difficulties caused by diffuse emissions, and also solves the problems associated with high moisture content of the drying medium. The basic idea is to use water vapour to determine the exhaust flow, while a dry ice trap is used both to preconcentrate emitted volatile organic compounds and to determine the moisture content of the drying medium. The method as used in this paper has an uncertainty of 13% using a 95% confidence interval. Emissions from a spouted bed (2) in continuous operation drying Norway spruce sawdust at temperatures of 140°C, 170°C or 200°C was analysed with FID and GC-MS. When the sawdust end moisture content was reduced below 10%wb, emissions of terpenes and volatile organic compounds per oven dry weight increased rapidly. Increased temperature of the drying medium increased the amounts of emitted monoterpenes when sawdust moisture content was below the fibre saturation point. Examination of sawdust and wood pellets from different pellets producers (3) revealed that most of the terpene emissions happened during the drying step, with rotary dryers causing higher emissions than steam dryers. Almost all of the volatile terpenes remaining in wood after drying were released during pelleting. When sawdust with higher moisture content was used in the pellets press, the terpene emissions were increased. Terpenes emitted naturally from vegetation can have an adverse environmental impact. Factors affecting terpene emissions from tree species in Sweden were reviewed (4). Models for prediction of terpene fluxes should include not only temperature but also light intensity, seasonal variation, and a base level of herbivory and insect predation. Prediction of high concentrations of ambient terpenes demand sufficient resolution to capture emission peaks e.g. those caused by bud break.

A variety of methods exist to remove volatile organic compound (VOC) air pollutants from contaminated gas streams. As regulatory and public opinion pressures increase, companies are searching for more effective methods to control these emissions. This document is intended as a guide to help determine if existing systems are adequate and to provide additional information to improve the efficiency of the systems. It explores conventional methods of controlling VOC emissions, as well as innovative technologies including membrane separation, plasma destruction, and ozone catalytic oxidation. The conventional technologies covered include condensation, adsorption, absorption (or scrubbing), thermal incineration, flaring, catalytic incineration, and biofiltration. Each chapter includes a description of the technology, a discussion of the types of systems available, notes on the design of the system, economic estimates, an explanation of potential problems, and a list of considerations for installation and maintenance concerns. The final chapter is dedicated to the preparation and characterization of metal catalysts which were developed to improve the reaction rate of VOCs using ozone as an oxidant.
Ph. D.

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.T his 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 adverse effects of contaminated outdoor air have been recognized and subject to control for many years. More recently environmental engineers and health professionals have become cognizant of the hazards associated with contaminated indoor air. It is now understood that contaminated indoor air negatively impacts human health, worker productivity, and physical property. Volatile organic compounds (VOCs) are a common class of indoor air pollutants. Building materials such as treated wood, pressed-wood products, wallboard, sealants, adhesives, floor coverings, and paints can be sources of VOC emissions. The knowledge-base necessary to develop effective solutions to indoor air quality problems requires an understanding of the emissions behavior of indoor materials. Environmental chambers are often utilized to characterize indoor material as sources of VOC emissions to indoor air. Chamber studies, although expensive and time consuming, can be utilized to provide estimates of the rates at which a particular material emits VOCs under a specific set of environmental conditions. By fitting curves to emissions data obtained through chamber studies, VOC emissions models have been constructed. These models are frequently empirical and as a consequence, 1) apply only to the specific material and environmental conditions investigated, 2) provide little understanding of the source/sink characteristics of the material, and 3) provide little knowledge of the mass transfer processes governing emissions behavior. As a result, our understanding of the mechanisms that control VOC emissions from indoor materials remains rudimentary. Physically-based models that describe the emissions characteristics of building materials would greatly facilitate the process of improving indoor air quality. Evidence exists suggesting well-established fundamental mass transfer mechanisms govern emissions from indoor materials. Of the various mechanisms governing emissions behaviors, diffusion appears to be one of the most significant. The primary objective of this research was to demonstrate that the VOC emissions source behavior of a diffusion-controlled homogenous building material could be predicted using a mechanistic mathematical model. A commercial grade sheet vinyl flooring (VF) was selected for study because VF is present in many residential and commercial buildings, is relatively homogenous, and has been shown to emit hazardous organic chemicals. If successful, this research would demonstrate that the proposed strategy could be generalized to other VOC sources using appropriately constructed mathematical models. Satisfying the research objective required development of a physically-based model to predict gas-phase VOC concentrations resulting from exposure to a diffusion-controlled material. Key parameters for this model are the solid-phase diffusion coefficient, D; the solid/air partition coefficient, K; and the initial solid-phase VOC concentration, C0. D and K have been previously quantified for only a few indoor materials and methods for determining C0 are rudimentary. Therefore, this research project required development and execution of methods for quantifying D, K, and C0. D and K were quantified using a recording microbalance. C0 was evaluated using a new technique of cryogenic milling followed by fluidized bed desorption. The model was validated by exposing a VF sample in an environmental chamber and directly measuring gas-phase VOC concentrations resulting from mass transfer from the solid material. Further model validation was achieved by directly measuring the VOC concentration profiles after exposure in environmental chambers. Because the key model parameters were quantified independently of chamber studies, the model validation process provided a rigorous test of the validity of the mass transfer model in particular and of the source characterization strategy in general. The results of this research contribute to our understanding of the fundamental mechanisms that govern emissions of VOCs from vinyl flooring and provide a sound theoretical foundation for characterization of a wide range of other sources of indoor VOCs. This understanding could facilitate product reformulation strategies aimed at preventing or reducing indoor air contamination. Mass transfer models could also be utilized to develop standards for the environmental performance of indoor materials. The proposed approach will prove useful in conjunction with broader studies on sick building syndrome to identify sources that may have a critical impact on the health and comfort of building occupants.
Ph. D.

Building materials are a major source of indoor air contaminants. Volatile organic compounds (VOCs) are an important class of contaminants prevalent in indoor air. Attempts have been made to model the emission of VOCs from building materials. Diffusion has been shown to control the rate of mass transfer within certain types of building materials. The primary objective of this research is to develop a fundamental diffusion-based model for single and double layer building materials. The single-layer model considers a slab of material located on the floor of a chamber or room with the material acting either as a source or a sink for VOCs. The behavior of the model is governed by the material phase diffusion coefficient (D), the material/air partition coefficient (K), the concentration of VOC in the influent air stream, and the initial concentration within the material phase. The single-layer model extends a previously developed version, incorporating the non-uniform initial concentration inside the building material and a transient influent concentration. Experimental work is performed to check the validity of the model. A steel chamber housing a piece of vinyl flooring is used to simulate building material within a room. D and K values for two representative VOCs, n-dodecane and phenol, are available from earlier experiments. These parameters are used in the model to predict the VOC concentration inside the chamber. The predicted values compare very well to the observed experimental data. A double layer version of the model is developed and studied from a theoretical perspective. The model also permits a time dependent influent concentration and a non-uniform initial concentration profile within each of the two layers. A parametric analysis is performed varying the ratio of the diffusion coefficients, the partition coefficients and the thickness of the two layers. Three cases of practical interest are studied using the double-layer model. The use of a thin low-permeability barrier layer placed on top of a building material is shown to hold considerable promise for reducing the emission rate of VOCs into indoor air.
Master of Science

Metabolomics is a post genomic field of research concerned with the study of low molecular weight compounds within a biological system permitting the investigation of the metabolite differences between natural and perturbed systems (such as cells, organs and tissues). Rapid identification and discrimination of biological samples based upon metabolic differences and physiological status in microbiology, mammalian systems (particularly for disease diagnosis), plants and food science is highly desirable. Volatile organic compound (VOC) profiling is a novel area of research where the composition of the VOCs emitted by the biological samples can be correlated to its origin and physiological status. The aim of this project was to investigate the applicability of VOC profiling as a potential complementary tool within metabolomics.In this project the discrimination of bacteria using a novel gas phase separation method was investigated and the development of VOC-based profiling tools for the collections of VOCs emitted from biological samples was also studied. The optimisation and validation of a high throughput method for VOC analysis was achieved and this was used to assess wound healing.VOC metabolite profiling was further extended to the discrimination of S. typhimurium contaminated meat; the study was conducted in parallel with metabolite profiling analysis for the analysis of non-volatile small molecules. Finally, enhanced vibrational spectroscopic techniques were applied to the characterisation and screening of dye molecules in contaminated foodstuffs using Raman spectroscopy. This thesis clearly demonstrates that VOC metabolic profiling is a complementary tool within the metabolomics toolbox, one of its great attractions is that it permits the characterisation of biological samples in a rapid and non-invasive manner. The technique provides detailed chemical information regarding the VOC composition present above the headspace of the sample and can be used to understand its physiological status and biological origin. VOCs metabolite profiling will become a valuable tool for non-invasive analysis of many biological systems. Raman spectroscopy is a sensitive and non-destructive technique which can generate detailed chemical and structural information regarding the analyte under investigation with little or no sample preparation needed. The effect of the weak Raman signal can be significantly amplified by coupling the analyte molecule to surfaces of nanoparticles and demonstrated that it is ideal for analysing aqueous dye solutions in a quantitative manner.

The focus of this dissertation is on the design and micro-fabrication of an all silicon gas chromatography column with a novel two dimensional resistive heater and on its integration with an ultra-low power Thermal Conductivity Detector (TCD) for fast separation and detection of Volatile Organic Compounds (VOC). The major limitations of the current MEMS-GC column are: direct bonding of silicon to silicon, and peak band broadening due to slow temperature programming. As part of this thesis, a new gold eutectic-fusion bonding technique is developed to improve the sealing of the column. Separation of BETX, alkane mixture and VOCs were demonstrated with the MEMS GC column. The time and power required to ramp and sustain the column’s temperature are very high for the current GC columns. To reduce the time required to separate the compounds, a new temperature gradient programming heating method was developed to generate temperature gradients along the length of the column. This novel heating method refocuses eluding bands and counteracts some of the chromatographic band spreading due to diffusion resulting in an improved separation performance. A low power TCD was packaged and tested in a GC by comparison against FID for the detection of a mixture of VOCs. It demonstrated low power operation of a few milliwatts and a very fast response. The MEMS-GC was also demonstrated for rapid detection of the VOC gases released by pathogenic species of Armillaria fungus.

Les composés organiques volatils (COV), les hydrocarbures saturés, insaturés et autres hydrocarbures substitués, jouent un rôle majeur dans la chimie atmosphérique. Ils sont principalement émis par des sources anthropiques et biogéniques dans l'atmosphère; ils sont également transformés in situ par des réactions chimiques, et plus spécifiquement par photo-oxydation conduisant à la formation d'ozone (O3) et d'aérosol organique secondaire (SOA). En modifiant la fraction organique des particules d'aérosol, les COV modifient l'équilibre radiatif de la Terre par un effet direct (absorption et diffusion du rayonnement solaire) ou par un effet indirect en altérant les propriétés microphysiques des nuages. Ils présentent également un effet direct sur la santé humaine et l'environnement. Au cours de leur transport atmosphérique, les COV et leurs produits d'oxydation, les composés organiques volatils oxygénés (OVOC), peuvent se répartir entre les phases gazeuses et aqueuses en fonction de leur solubilité. Les nuages ​​ont un effet significatif sur la chimie troposphérique en redistribuant les traces de constituants entre les phases et en fournissant de l'eau liquide dans laquelle la chimie de la phase aqueuse peut avoir lieu. En effet, pendant la durée de vie des nuages, les composés chimiques et notamment les COV se transforment efficacement car les nuages ​​favorisent le développement d'une «chimie multiphasique». Cette dernière présente plusieurs particularités. Premièrement, les processus photochimiques à l'intérieur des gouttelettes sont importants dans la transformation des composés chimiques. Deuxièmement, les réactions chimiques aqueuses sont efficaces et peuvent être plus rapides que les réactions équivalentes en phase gazeuse. Cela peut être lié à la présence d'oxydants puissants tels que le peroxyde d'hydrogène H2O2 ou les ions métalliques de transition (TMI), qui participent à la formation de radicaux tels que les radicaux hydroxyles (HO •) qui favorisent les processus d'oxydation. De plus, la présence de micro-organismes viables a été mise en évidence et a montré sa participation aux transformations des espèces chimiques. Enfin, ces transformations dans les nuages ​​sont également fortement perturbées par des processus microphysiques qui contrôlent la formation, la durée de vie et dissipation des nuages. Ces processus redistribueront les espèces chimiques entre les différents réservoirs (eau de nuages, pluie, phase particulaire, phase gazeuse et phase de glace solide). Dans ce cadre, la transformation des COV dans le milieu nuageux peut conduire à la production de composés secondaires contribuant à la formation de SOA, appelés «nuage aqSOA». Cette masse d'aérosol organique secondaire produite pendant la durée de vie du nuage pourrait expliquer en partie l'ubiquité des petits acides dicarboxyliques et céto et des composés de haut poids moléculaire mesurés dans les particules d'aérosol, l'eau de brouillard, l'eau de nuage ou l'eau de pluie à de nombreux endroits, car ils n'ont ni sources d'émission directe ni aucune source importante identifiée en phase gazeuse. Cette masse d'aqSOA reste en phase particulaire après évaporation des nuages ​​impliquant une modification des propriétés (micro) physiques et chimiques des particules d'aérosol (taille des particules, composition chimique, morphologie). Ceci conduit à des modifications de leurs impacts sur les cycles consécutifs de nuages ​​ou de brouillard (effets indirects des aérosols) et de leurs interactions avec les rayonnements entrants par diffusion / absorption (effet direct des aérosols). (...)
Volatile Organic Compounds (VOC), including saturated, unsaturated, and other substituted hydrocarbons, play a major role in atmospheric chemistry. They are primarily emitted by anthropogenic and biogenic sources into the atmosphere; they are also transformed in situ by chemical reactions, and more specifically, by photo-oxidation leading to the formation of ozone (O3) and Secondary Organic Aerosol (SOA). By altering the organic fraction of aerosol particles, VOC modify the Earth’s radiative balance through a direct effect (absorption and scattering of solar radiation) or through indirect effect by altering cloud microphysical properties. They also present a direct effect on human health and on the environment.During their atmospheric transport, VOC and their oxidation products, Oxygenated Volatile Organic Compounds (OVOC), may partition between the gaseous and aqueous phases depending on their solubility. Clouds have a significant effect on tropospheric chemistry by redistributing trace constituents between phases and by providing liquid water in which aqueous phase chemistry can take place. Indeed, during the cloud lifetime, chemical compounds and particularly VOC are efficiently transformed since clouds favor the development of complex “multiphase chemistry”. The latter presents several particularities. First, photochemical processes inside the droplets are important in the transformation of chemical compounds. Second, aqueous chemical reactions are efficient and can be faster than the equivalent reactions in the gas phase. This can be related to the presence of strong oxidants such as hydrogen peroxide H2O2 or Transition Metal Ions (TMI), which participate in the formation of radicals such as hydroxyl radicals (HO•) that favor oxidation processes. Furthermore, the presence of viable microorganisms has been highlighted and shown to participate in transformations of the chemical species. Finally, these transformations in clouds are also strongly perturbed by microphysical processes that control formation, lifetime and dissipation of clouds. These processes will redistribute the chemical species between the different reservoirs (cloud water, rain, particle phase, gaseous phase, and solid ice phase). In this frame, the transformation of VOC in the cloud medium can lead to the production of secondary compounds contributing to SOA formation, reported as “cloud aqSOA”. This secondary organic aerosol mass produced during the cloud lifetime could explain in part the ubiquity of small dicarboxylic and keto acids and high molecular-weight compounds measured in aerosol particles, fog water, cloud water, or rainwater at many locations, as they have neither substantial direct emission sources nor any identified important source in the gas phase. This aqSOA mass stays in the particle phase after cloud evaporation implying a modification of the (micro)physical and chemical properties of aerosol particles (particle size, chemical composition, morphology). This leads to modifications of their impacts on consecutive cloud or fog cycles (aerosol indirect effects) and of their interactions with incoming radiation by scattering/absorbing (aerosol direct effect). (...)

The widespread usage of products containing volatile organic compounds (VOC) has lead to a general human exposure to these chemicals in work places or homes being suspected to contribute to the growing incidence of environmental diseases. Since the causal molecular mechanisms for the development of these disorders are not completely understood, the overall objective of this thesis was to investigate VOC-mediated molecular effects on human lung cells in vitro at VOC concentrations comparable to exposure scenarios below current occupational limits. Although differential expression of single proteins in response to VOCs has been reported, effects on complex protein networks (proteome) have not been investigated. However, this information is indispensable when trying to ascertain a mechanism for VOC action on the cellular level and establishing preventive strategies. For this study, the alveolar epithelial cell line A549 has been used. This cell line, cultured in a two-phase (air/liquid) model allows the most direct exposure and had been successfully applied for the analysis of inflammatory effects in response to VOCs. Mass spectrometric identification of 266 protein spots provided the first proteomic map of A549 cell line to this extent that may foster future work with this frequently used cellular model. The distribution of three typical air contaminants, monochlorobenzene (CB), styrene and 1,2 dichlorobenzene (1,2-DCB), between gas and liquid phase of the exposure model has been analyzed by gas chromatography. The obtained VOC partitioning was in agreement with available literature data. Subsequently the adapted in vitro system has been successfully employed to characterize the effects of the aromatic compound styrene on the proteome of A549 cells (Chapter 4). Initially, the cell toxicity has been assessed in order to ensure that most of the concentrations used in the following proteomic approach were not cytotoxic. Significant changes in abundance and phosphorylation in the total soluble protein fraction of A549 cells have been detected following styrene exposure. All proteins have been identified using mass spectrometry and the main cellular functions have been assigned. Validation experiments on protein and transcript level confirmed the results of the 2-DE experiments. From the results, two main cellular pathways have been identified that were induced by styrene: the cellular oxidative stress response combined with moderate pro-apoptotic signaling. Measurement of cellular reactive oxygen species (ROS) as well as the styrene-mediated induction of oxidative stress marker proteins confirmed the hypothesis of oxidative stress as the main molecular response mechanism. Finally, adducts of cellular proteins with the reactive styrene metabolite styrene 7,8 oxide (SO) have been identified. Especially the SO-adducts observed at both the reactive centers of thioredoxin reductase 1, which is a key element in the control of the cellular redox state, may be involved in styrene-induced ROS formation and apoptosis. A similar proteomic approach has been carried out with the halobenzenes CB and 1,2-DCB (Chapter 5). In accordance with previous findings, cell toxicity assessment showed enhanced toxicity compared to the one caused by styrene. Significant changes in abundance and phosphorylation of total soluble proteins of A549 cells have been detected following exposure to subtoxic concentrations of CB and 1,2-DCB. All proteins have been identified using mass spectrometry and the main cellular functions have been assigned. As for the styrene experiment, the results indicated two main pathways to be affected in the presence of chlorinated benzenes, cell death signaling and oxidative stress response. The strong induction of pro-apoptotic signaling has been confirmed for both treatments by detection of the cleavage of caspase 3. Likewise, the induction of redox-sensitive protein species could be correlated to an increased cellular level of ROS observed following CB treatment. Finally, common mechanisms in the cellular response to aromatic VOCs have been investigated (Chapter 6). A similar number (4.6-6.9%) of all quantified protein spots showed differential expression (p<0.05) following cell exposure to styrene, CB or 1,2-DCB. However, not more than three protein spots showed significant regulation in the same direction for all three volatile compounds: voltage-dependent anion-selective channel protein 2, peroxiredoxin 1 and elongation factor 2. However, all of these proteins are important molecular targets in stress- and cell death-related signaling pathways.
Die vermehrte Verwendung von Produkten, welche flüchtige organische Substanzen (VOC - volatile organic compound) enthalten, hat eine generelle Exposition der Bevölkerung mit diesen Substanzen an Arbeitsplätzen aber auch in Wohnräumen bedingt. VOCs stehen im Verdacht, zur zunehmenden Inzidenz umweltbedingter Erkrankungen beizutragen. Da die molekularen Ursachen dieser Erkrankungen bisher noch unverstanden sind, war es ein übergeordnetes Ziel dieser Arbeit, VOC-vermittelte molekulare Effekte in menschlichen Lungenepithelzellen anhand eines in vitro Modells zu untersuchen. Dabei sollten vor allem Konzentrationen unterhalb der gültigen Arbeitsplatzgrenzwerte untersucht werden. Obwohl Effekte auf einzelne Proteine bekannt sind, wurden bisher keine Effekte der VOC-Exposition auf das komplexe Netzwerk der zellulären Proteine (Proteom) untersucht. Dieses Wissen ist essentiell, um induzierte zelluläre Mechanismen zu verstehen und Strategien zu deren Vermeidung zu entwickeln. Für die hier durchgeführten Untersuchungen wurde die Lungenepithelzelllinie A549 in einem Zweiphasenexpositionsmodell eingesetzt. Dieses ermöglichte eine möglichst direkte zelluläre Exposition und wurde bereits erfolgreich verwendet, um durch VOC hervorgerufene Entzündungseffekte zu identifizieren. Die massen-spektrometrische Identifikation von 266 Proteinflecken lieferte die erste umfassende Proteomkarte der A549 Zelllinie, welche nachfolgende Untersuchungen mit diesem häufig verwendeten Zelltyp erleichtern wird. Zusätzlich wurde die Verteilung der drei gängigen Luftkontaminanten Chlorbenzol (CB), Styrol and 1,2-Dichlorobenzol (1,2-DCB) zwischen den beiden Phasen (gas/flüssig) des Expositionsmodells gaschromatographisch bestimmt. Die Verteilung entsprach den verfügbaren Literaturdaten. Anschließend wurde das modifizierte Expositionsmodell erfolgreich eingesetzt, um styrol-vermittelte Effekte auf das Proteom der A549 Zellen zu charakterisieren (Kapitel 4). Zu Beginn erfolgte die Erfassung der Zelltoxizität der Substanz, um sicher zu stellen, daß der überwiegende Teil der späteren Expositionsexperimente mit subtoxischen Konzentrationen durchgeführt wird. Es konnte eine signifikant veränderte Expression und Phosphorylierung der löslichen Proteinfraktion der A549 Zellen als Reaktion auf die Styrolexposition festgestellt werden. Die regulierten Proteine wurden massenspektrometrisch identifiziert und ihre wichtigsten Funktionen wurden zugewiesen. Validierungsexperimente auf Protein- und auf Transkriptebene bestätigten die 2-DE Ergebnisse. Insgesamt konnte die zelluläre Reaktion durch die styrol-vermittelte Induktion zweier zentraler Mechanismen erklärt werden: oxidativer zellulärer Stress und beginnende Apoptose. Folgeexperimente wie die Messung der Menge der zellulären reaktiven Sauerstoffspezies (ROS) und die Induktion von redox-sensitiven Markerproteinen konnte die Hypothese eines styrol-induzierten oxidativen Milieus bestätigen. Schließlich wurden Proteinaddukte des reaktiven Styrolmetaboliten Styrol 7,8 epoxide (SO) identifiziert. Besonders die SO-Addukte, welche and den beiden aktiven Zentren der Thioredoxin Reduktase 1 gefunden wurden könnten eine wichtige Rolle bei der styrol-induzierten ROS-Bildung sowie der beginnenden Apoptose spielen. In Analogie zum Styrolexperiment wurden die Effekte der halogenierten Benzole CB und 1,2-DCB untersucht (Kapitel 5). Es konnten ebenfalls sämtliche Proteine identifiziert und die wichtigsten zellulären Funktionen zugewiesen werden. Diese Substanzen modulierten ebenfalls apoptotische Signalwege und die zelluläre Antwort auf oxidativen Streß. Der beobachtete starke pro-apoptotische Effekt konnte für beide Substanzen mit der Spaltung der Caspase 3 nachgewiesen werden. Weiterhin konnte für CB die Induktion redox-sensitiver Proteinspezies mit einem beobachteten höherem Gehalt an ROS erklärt werden. Schließlich wurden ähnliche Mechanismen der zellulären Antwort auf die Exposition mit den drei untersuchten aromatischen VOCs diskutiert (Kapitel 6). Alle getesteten VOCs verursachten eine vergleichbare differentielle Expression (p<0,05) von 4,6-6,9% aller quantifizierten Proteinspezies. Nur drei Proteinspots wurden dabei gemeinsam für alle VOCs reguliert: voltage-dependent anion-selective channel protein 2, peroxiredoxin 1 and elongation factor 2. Allerdings gehören diese drei Proteine zu wichtigen zellulären Zielstrukturen der Signalwege für Stressantwort und Zelltod.

Ce travail de thèse vise à caractériser l’interaction entre composés organiques volatils et poussières minérales atmosphériques. Les COV sélectionnés sont l’isopropanol (IPA), l’isoprène (ISP) et l’acide acétique (AcA). Cinq échantillons naturels de poussières minérales provenant de zones désertiques situées dans plusieurs régions du globe ont été retenus.Il a été mis en évidence que l’origine et donc la composition chimique des poussières naturelles joue un rôle majeur dans la nature de leur interaction avec les COV. Plus particulièrement, les coefficients de capture tendent à croître avec les rapports élémentaires Al/Si et Fe/Si. De plus, il est montré que l’interaction entre COV et poussières est fortement impactée par l’humidité relative et la température.Plusieurs modes d’interaction entre les COV et les poussières étudiés ont été mis en évidence : physisorption, chimisorption ou adsorption réactive. Ils dépendent de la composition chimique des poussières et de la structure des COV. En fonction du mode d’interaction, ces processus hétérogènes peuvent être considérés comme des puits de COV primaires voire des sources de COV secondaires en phase gazeuse. Ce travail met en lumière la contribution des processus hétérogènes dans l’atmosphère
This thesis investigates the interactions of volatile organic compounds (VOCs) with natural mineral dust samples. The VOCs used are isopropanol (IPA), isoprene (ISP) and acetic acid (AcA). Five natural mineral dust samples originating from various desert regions all over the world are used in this study.It is evidenced that the origin, I.E. the chemical composition, of the natural dust sample plays a significant role in defining the nature of its interaction with the VOCs. In particular, an increase of uptake is observed with increasing Al/Si and Fe/Si elemental rations. Moreover, the dust-VOC interaction is evidenced as being highly impacted by relative humidity and temperature.Various interactions modes have been evidenced between dust and VOCs such as physisorption, chemisorption and reactive sorption depending on the chemical composition of the dust and the structure of the VOC. Depending on the interaction mode, heterogeneous processes can act as a sink of primary VOCs or even a soure of secondary oxygenated VOCs in the gas phase. This work emphasiez the contribution of heterogeneous processes to the atmosphere

The research focuses on the environmental problem of volatile organic compounds in ambient air of petrol filling stations. The literature review of the issues, arising from petrol-related VOCs, with actual and proposed VOC emissions trends in Europe, have been performed. Besides petrol filling station’s typical technology layout, petrol nature and composition, applicable petrol vapour recovery solutions and their efficiency were examinated. The volatile organic compounds’ experimental research in two petrol stations of typical technology layout in Vilnius city under similar extreme meteorological conditions (VOC air pollution episodes with low winds, stable stratification and suspended photochemical removal) is done. The emitted from petrol stations VOC experiment is based on air pumped sampling in glass gas pipette and further determination using gas chromatography with flame ionization detector. The experimental results, presented by means of tables and diagrams, are analysed and discussed. The available results of the experiment are loaded into the environmental model “ALOHA” for air pollution evaluation and concentrations prediction in the ambient air under different meteorological conditions and technological emergency situations (petrol spillage) at petrol filling station. The research is summarized in conclusions and recommendations.
Tyrimas skirtas aplinkos oro taršos problemai lakiaisiais organiniais junginiais, išsiskiriančiais nuo benzino degalinių. Atlikta svarstomos aplinkosauginės problemos literatūros apžvalga. Apžvelgti oro taršos pasekmės skatinamos LOJ išsiskyrimų nuo benzino degalinių, aktualios ir numatomos LOJ emisijų tendencijos Europoje, tipinis benzino degalinės technologijos išsidėstymas, benzino sudėtis ir svarbiausios LOJ garų formavimui benzino savybės, taikomi garų grąžinimo sprendiniai ir jų efektyvumas. Detaliai aprašytas LOJ eksperimentinis tyrimas, atliktas dviejose Vilniaus miesto tipinės technologijos degalinėse esant panašioms kraštutinėms (LOJ taršos epizodai prie silpnų vėjų, stabilios stratifikacijos ir suspenduoto fotocheminio šalinimo) meteorologiniams sąlygoms. LOJ mėginių ėmimui panaudotas aktyvus metodas su aspiracija į dujines pipetes, LOJ koncentracijos nustatytos dujinės chromatografijos su liepsnos jonizacijos detektoriumi metodu. Tyrimo rezultatai, pateikti lentelių ir diagramų pavidalu, aptarti ir įvertinti. Eksperimento duomenys įkelti į oro kokybės modelį “ALOHA”, siekiant nustatyti LOJ pernašą ir sudaryti LOJ koncentracijų prognozė benzino degalinių aplinkos ore prie skirtingų meteorologinių parametrų ir avarinių technologinių situacijų (benzino išsiliejimas). Tiriamąjį darbą reziumuoja išvados ir rekomendacijos.

Content: As it is known in the tanning sector, in recent times, the so-called wet-white and/or metal-free concepts have had a certain increase. For example, in the automotive sector, the wet-white tanning system, carried out with glutaraldehyde and tannins, has been widely diffused. In fact, car manufacturers offer, for interior furnishings, leather not only for high-end cars but increasingly also in the lower segments. The components on which the leather upholstery is applied are mainly steering wheel, seats, dashboard and panels. Therefore, the use of leather also in this context must be able to meet both the aesthetic/performance criteria and the environmental ones; environmental criteria should also consider the air quality of the interior of a motor vehicle. In practice, the interior furniture consisting of finished leather must be able to release a few volatile substances and, at the same time, provide a typical smell of leather. Considering, therefore, the diffusion of alternative chrome tanning systems for the different uses, in this work, wet-white (glutaraldehyde and tannins) will be investigated, both from the point of view of the performance characteristics and from the ecotoxicological ones. and leathers deriving from the latest generation of metal-free tanning. For the characterization of Volatile Organic Compounds (VOC) the GC-MS will be used coupled with the 'Purge and Trap' technique with the aim of obtaining information on the new substances used in the wetwhite / metal free production process and then avoiding undesired effects during use (eg bad smell, SVHC substances, etc.) Take-Away: metal-free automotive VOC

Humans today spend most of their time in various indoor settings such as housing, schools and workplaces. The quality of the indoor environment is therefore of great significance for our wellbeing. However, it has been suggested that the indoor environment contains over 6000 organic compounds, such as various volatile organic compounds (VOC). Around 500 of these compounds is believed to be due to emissions from different surrounding building materials such as insulation, plastic film, sealants and flooring. This study targeted building materials from three low energy preschools that were sampled and analyzed for emissions of VOCs and nine different organophosphate flame retardant compounds (OPFR) using a gas chromatograph coupled to a mass spectrometer (GC/MS). Low energy buildings are buildings that is particularly air tight to be so energy efficient as possible. The study uses a qualitative approach and therefore mainly identifies possible contribution from building materials to indoor environment. More than 100 different VOCs was identified and the most noticeable were meta-, ortho- and para-xylene, toluene, n-hexane and propylene glycol, all but the last compound is associated with hazardous health effects. The building materials that emitted the largest amounts of VOCs was sealants and adhesives. Linoleum flooring and acrylic was also large emitters. Tris(1-chloro-2-propyl) phosphate (TCIPP) were identified in all samples and all nine targeted OPFR compounds were identified in the various material samples and dust samples. T-Flex tape and plastic film was the sample materials that emitted most OPFR compounds.

There are few published direct measurements of the atmosphere-surface exchange of volatile organic compounds (VOCs), particularly for biogenic VOCs (BVOCs). Global modelling of atmospheric chemistry and transport of BVOCs has large uncertainties due to the very small number of measurements in tropical regions, which are responsible for half the global BVOC emissions. This thesis presents direct measurements of concentrations and ecosystem fluxes of BVOCs in different regions (Tropics, Mediterranean) using the approach of virtual disjunct eddy covariance (vDEC) combined with proton transfer reaction mass spectrometry (PTR-MS) – a real-time BVOC sensor. The field measurements also included methodological developments of the vDEC/PTR-MS approach, which will be of value to the wider flux measurement community. A novel approach to determining the lag time between the vertical wind measurement and the air concentration measurement has been developed that will greatly reduce the uncertainty in the derived flux measurements. In the laboratory, the selectivity of PTR-MS was investigated by designing an alternating drift-voltage mode (AD-PTR-MS) to discriminate between structural isomers detected at the same m/z channel, with monoterpenes used as model compounds. The results of the measurements, particularly from the rainforest and oil palm plantations in Borneo, are novel and therefore provide important experimental constraints on models of atmospheric emissions, chemistry and transport. For example, although parameters which work reasonably well can be derived for model algorithms for the emission of isoprene from the rainforest, their performance over oil palms was less good, because of circadian controls of emissions from oil palms. However, the larger problem is the measured basal emission rates (BERs) which are significantly smaller than those used by default in the global MEGAN model. Another novel finding was the high deposition velocities of MVK and MACR (isoprene first order oxidation products) which at the oil palm plantation commonly exceeded 1 cm s-1; this result has implications for atmospheric modelling. The successful field results relied on significant developments in software for data acquisition and processing, and operational optimisation of the PTR-MS instruments in the extreme humidity encountered during the fieldwork in Borneo.

Exhaled breath is a rich and complex matrix containing many hundreds of compounds. Every breath offers the potential of a non-invasive measurement of the biochemical processes occurring in the human body and it is this notion that has led to the application of breath analysis for the detection of disease. With the majority of research in the field being focused on the detection of biomarkers, little has been presented on how the seemingly homeostatic matrix of breath varies during the course of normal life events. The research in this thesis describes how a subject's emotional state, physical state, and daily activities can alter the composition of exhaled breath.

In this study, atmospheric levels and sources of VOCs at Aliaga industrial area was investigated. For this, VOC concentrations were measured at two monitoring stations through winter and summer campaigns in 2005 and 2006. Sampling stations were located in downtown Aliaga and downwind of industrial facilities, approximately 500 m to the south east of Horozgedigi village. After the summer sampling, another temporary station was installed in between PETKIM and TÜ
PRAS, named as TÜ
PRAS Station to generate TÜ
PRAS and PETKIM profiles. More than 50 species were measured in all stations. In all stations, toluene has the highest contribution to total VOC concentration. Toluene is followed by m,p-xylene and benzene. While higher concentrations of traffic related VOCs were measured at Aliaga station, VOCs from industrial solvents and industrial processes were higher at Horozgedigi station. The concentration levels in Aliaga and Horozgedigi are found to be comparable to the other industrial regions reported in the literature. Investigation of episodes, diurnal variations of VOCs and meteorological parameters showed that PETKIM and TÜ
PRAS emissions affect the concentrations levels at Horozgedigi and Aliaga stations. Source profiles of PETKIM and TÜ
PRAS are determined by using the TÜ
PRAS station data set. 2-methyl-hexane, benzene and 2,2,3-tri-methyl-butane+2,3-di-methyl-pentane are found to be good markers of PETKIM emissions. Ten different VOC sources were identified in the region. These were gasoline exhaust, diesel exhaust, natural gas use, gasoline evaporation, industrial emissions-1, natural gas construction, non-industrial solvent use, industrial emissions-2, PETKIM emissions, and mixed emissions from PETKIM and shipbreaking facilities.

Escalating energy and environmental issues are driving researchers and industries throughout the world to study gas separation. Being common toxic gases, volatile organic compounds (VOCs) must be removed from the atmosphere. When compared to the conventional adsorption process, e.g. packed bed to separate VOC, the adsorbent hollow fibre has exhibited advantages in low-pressure drop, easy operation and lower capital cost with high adsorption performance. This research investigates the optimisation and development of single and multi-channel adsorbent hollow fibres to improve the mechanical properties, flexibility, adsorbent loading and enhance adsorption capacity. These fibres are made up of an adsorbent (13X zeolite, HiSiv 1000 zeolite powder and HiSiv 3000 zeolite powder) held together with a polymer (polyethersulfone) binder through wet/wet spinning followed by a phase inversion process. Single adsorbent hollow fibres were optimised by changing the ratio of adsorbent to the polymer, the viscosity of polymer/adsorbent/solvent mixtures, the pre-treatment temperature and by adding a pore former. This optimal recipe of polymer/adsorbent/solvent mixtures was then used to fabricate tri-lobe and hexagonal multi-channel adsorbent hollow fibre. The adsorption performance and mechanical properties of these multi-channel fibres were compared to those of the single adsorbent hollow fibres. Dynamic adsorption challenges were carried out using n-butane as the VOC model gas to provide breakthrough curves using a flame ionisation detector (FID) hydrocarbon analyser. Scanning electron microscopy (SEM) was used to characterise the surface and porous structures of the different adsorbent hollow fibres formation. Adsorption isotherm experiments were also used to measure the surface area of adsorbent hollow fibres. In order to understand the transport mechanism of gases through adsorbent hollow fibres, single and multi-channel fibres were modelled using a computational fluid dynamics (CFD) using COMSOL software 5.2, thus enabling the prediction of breakthrough time and mass transfer for the new geometries of adsorbent hollow fibre.

2017 - 2018
In the last decades, atmospheric pollution has become an increasingly alarming problem, due to its adverse effects at the global, regional and local scales. In this context, the emissions of Greenhouse Gases (GHGs), Volatile Organic Compounds (VOCs) and odours from chemical manufacturing plants, petrochemical sector and other hazardous sources pose a major challenge. Global warming, due to increased GHGs level in the atmosphere, has been identified as one of the key challenges in this century. Indeed, the impacts of global warming have caused severe damages towards human and environment ecosystem. VOCs are included among the priority gaseous organic contaminants, with BTEX identified among the most dangerous for human health. They are also considered responsible for the photochemical pollution as a result of their reaction in the atmosphere with nitrogen oxides in presence of solar radiation. In addition, their tendency to volatilize readily to the atmosphere leads to problems connected to odour annoyance. These aspects triggered the enforcement of stricter regulations and, consequently, boosted the necessity of properly manage atmospheric emissions. The conventional chemical-physical processes mainly used for the treatment of these kinds of emissions envisage the contaminants transfer to other phases and, thus, the necessity of further treatments. Biological processes and Advanced Oxidation Processes (AOPs), instead, are able to support the degradation and mineralization of organic compounds, resulting in more effective solutions. Furthermore, AOPs applied as pretreatments at biological processes may improve VOCs biotreatability and control the accumulation of biomass. Moreover, since the biological treatment of high concentrations of VOCs might cause a limitation of the oxygen available for the aerobic degradation due to the reduced water-solubility of this compound, the synergic activity of microalgae and bacteria represents an efficient alternative to support the simultaneous abatement of CO2 and VOCs. In algal-bacterial photo-bioreactors, microalgae produce oxygen during the photosynthetic process in the presence of light and CO2, while heterotrophic bacteria utilize the additional O2 supply to accelerate the oxidation of organic compounds. In turn, the CO2 resulting from the mineralization process is fixed by the microalgae. Mechanisms underlying microalgae activity might not only prevent oxygen limitation but also enhance the biodegradability of the target VOC. In this context is framed the research activity discussed in the present work, aimed to:  the comparative evaluation of UV-assisted ozonation and its combination with conventional processes in different operating conditions;  the comparative evaluation of two different biological reactors and the assessment of their continuous toluene degradation performances under different operating conditions;  the scale-up of the proposed systems and the assessment of the technical feasibility. To this end, experimental activity was structured in two main steps:  the first one was focused on the assessment of ozone and photolysis effectiveness in promoting toluene degradation;  the second part was focused on the assessment of enhanced biological processes for the continuous removal of gaseous toluene. The first part of the research, focused on the comparative assessment of different configuration of AOPs systems, was performed at the Sanitary Environmental Engineering division (SEED) of Salerno University. Toluene was identified as target compound for the experimental activities. A lab-scale UV/O3 reactor was investigated for the degradation of VOCs emissions under different operating conditions, in order to highlight the influence of the inlet concentrations and the ozone dosages. A novel configuration with an additional scrubbing phase is proposed and assessed to improve the removal efficiency and to prevent the release of polluting intermediates of the single-step process. The combined system boosted higher performance and stability compared to the stand-alone (UV/O3) process along with a more economical and environmental sustainability. In the second phase, the experimental activity was performed at the Department of Chemical Engineering and Environmental Technology of Valladolid University. The experimental activity aimed at evaluating and systematically comparing the continuous toluene degradation performance of the proposed biological reactors, a conventional bacterial Biotrickilng Filter (BTF) and an innovative Tubular Photo-BioReactor (TPBR). Different operating conditions have been investigated, varying the Empty Bed Residence Time (EBRT) and the toluene inlet concentration to gradually increase the Inlet Load (IL) entering the systems. Toluene mass transfer tests have been carried out in order to determine the limiting stage, and a final robustness test performed to assess the capacity of the systems to face inlet load fluctuations. The results obtained demonstrated the potential of the synergic effects between bacteria and microalgae. The higher DO concentrations ensured oxygen availability for the microbial community and improved the process performances. The carbon dioxide released from mineralization process was utilized for the valuable biomass production. Conventional processes with AOPs pretreatment and microalgae-bacteria consortium inoculation thus represent innovative and promising methods for the increase of treatment efficiencies, biomass valorization and GHGs reduction. The combination of conventional and advanced processes represents a sustainable platform to reduce the emission of undesirable byproducts, besides treating high concentrations of VOC. [edited by Author]
XXXI ciclo

Tidigare studier har visat att äggläggande malariavektorer attraheras till vissa flyktiga organiska ämnen (VOC) som finns i olika gräsarter. Syftet med den här studien var att verifiera att flyktiga organiska ämnen finns i fyra olika gräsarter från Kenya; Panicum repens,Cynodon dactylon och Cyperus papyrus med Pennisetum setaceum rubrum som kontroll förde andra gräsarterna. För att analysera de flyktiga organiska ämnena extraherades gräset medhjälp av ultraljudsextraktion (UAE) och fastfasextraktion (SPE). De flyktiga organiska ämnena analyserades med gaskromatografi- masspektrometri (GC-MS). På grund av utbrottet av COVID-19 så analyserades istället resultat från en tidigare studie som använde samma metod. Det visades att Cyperus rotundus innehöll flera olika terpener och det antogs att Cyperus papyrus också innehåller några av dess föreningar. Det drogs också slutsatsen attbåde UAE och SPE ska användas för att ge bästa resultat med avseende på mängden analytersom extraherats. Fortsättningsvis så drogs slutsatsen att då UAE ska användas så är acetonitril att föredra över metanol som lösningsmedel. Den här studien är en översikt av den tidigare nämnda metodiken.

Many industrial processes handling organic solvents produce volatile organic compounds (VOCs). These VOCs not only cause environmental pollution, but also represent an economic loss. VOC removal and recovery have become a big issue that needs to be addressed. Traditional techniques for VOCs removal include carbon adsorption, condensation, and absorption, and none is efficient enough to meet every need. Membrane separation has emerged as an excellent alternative or complementary technology for VOC separation. Separation of VOCs from nitrogen by composite hollow fiber membranes is studied in this thesis. Microporous hollow fiber membranes were spun from polyvinylidene fluoride (PVDF) using the phase inversion method, and the hollow fibers were coated with a thin layer of poly(ether block amide) (PEBA), thereby forming composite membranes. PVDF was chosen as the substrate material because of its excellent thermal and chemical stabilities and good mechanical strength, and PEBA was selected as the active separating layer because of its good permselectivity and film forming properties. In PEBA polymer, the hard polyamide blocks provide high mechanical strength, and the soft polyether blocks provide flexibility and elasticity. This study is focused on the preparation and characterization of PEBA/PVDF composite hollow fiber membranes. The membranes were tested for the removal of representative VOCs including hexane, heptane and cyclohexane, which are the main components of gasoline, and dimethyl carbonate (DMC), ethanol, methanol, and methyl t-butyl ether (MTBE) that are the oxygenates and octane number enhancers of gasoline. The separation of gasoline vapor from nitrogen was also investigated. It was found that the PEBA/PVDF composite hollow fiber membranes are effective for the separation of hydrocarbon vapors from nitrogen. The effects of hollow fiber membrane preparation conditions on the membrane performance were studied, and the separation performance of the composite hollow fiber membranes at various operating conditions (e. g. feed concentration, operating temperature) was evaluated.

Non-thermal plasma generated in a dielectric barrier packed-bed reactor has been used for the remediation of chlorinated volatile organic compounds. Chlorinated VOCs are important air pollutant gases which affect both the environment and human health. This thesis uses non-thermal plasma generated in single and multiple packed-bed plasma reactors for the decomposition of dichloromethane (CH2Cl2, DCM) and methyl chloride (CH3Cl). The overall aim of this thesis is to optimize the removal efficiency of DCM and CH3Cl in air plasma by investigating the influence of key process parameters. This thesis starts by investigating the influence of process parameters such as oxygen concentration, initial VOC concentration, energy density, and plasma residence time and background gas on the removal efficiency of both DCM and CH3Cl. Results of these investigations showed maximum removal efficiency with the addition of 2 to 4 % oxygen to nitrogen plasma. Oxygen concentrations in excess of 4 % decreased the decomposition of chlorinated VOCs as a result of ozone and NOx formation. This was improved by adding an alkene, propylene (C3H6), to the gas stream. With propylene additives, the maximum remediation of DCM was achieved in air plasma. It is thought that adding propylene resulted in the generation of more active radicals that play an important role in the decomposition process of DCM as well as a further oxidation of NO to NO2. Results in the single bed also showed that increasing the residence time increased the removal efficiency of chlorinated VOCs in plasma. This was optimized by designing a multiple packed-bed reactor consisting of three packed-bed cells in series, giving a total residence time of 4.2 seconds in the plasma region of the reactor. This reactor was used for both the removal of DCM, and a mixture of DCM and C3H6 in a nitrogen-oxygen gas mixture. A maximum removal efficiency of about 85 % for DCM was achieved in air plasma with the use of three plasma cells and the addition of C3H6 to the gas stream. Nitrogen oxides are air pollutants which are formed as by-products during the decomposition of chlorinated VOCs in plasmas containing nitrogen and oxygen. Results illustrate that the addition of a mixture of DCM and C3H6 resulted in the formation of the lowest concentration of nitric oxide, whilst the total nitrogen oxides concentrations did not increase. A summary of the findings of this work is presented in chapter eight as well as further work. To conclude, the maximum removal efficiency of dichloromethane was achieved in air plasma with the addition of 1000 ppm of propylene and the use of three packed-bed plasma cells in series. The lowest concentration of nitric oxide was formed in this situation.

Els compostos orgànics volàtils biogènics (COVBs) juguen un paper important en l'ecologia i la química atmosfèrica. Les emissions d'aquests COVBs pels ecosistemes terrestres són degudes principalment a les plantes i estan molt influenciades per les variacions en les variables ambientals i, per tant, es veuen afectades per l'augment del canvi ambiental global. No obstant això, aquestes emissions i les seves influències no són ben conegudes en els ecosistemes mediterranis. Si bé els COVBs del sòl aparentment tenen un paper menor en la química atmosfèrica, per la seva fracció generalment baixa pel que fa a les emissions totals dels ecosistemes de tipus mediterrani, tenen un paper ecològic important en els processos del sòl. Molts estudis anteriors sobre COVs del sòl han analitzat els fluxos, mentre que les concentracions reals de COVs en els sòls dels ecosistemes mediterranis no s'han considerat fins ara. En aquest treball, faig el seguiment d'experiments de manipulació ambiental en ecosistemes típics mediterranis per estudiar els intercanvis de COVs, incloses les emissions de les plantes, i els intercanvis i concentracions de sòls, i els factors que els determinen. L'arbust Erica multiflora L., espècie abundant en matolls mediterranis i l'arbre Quercus ilex L., espècie dominant en molts boscos mediterranis van ser les espècies estudiades, la primera al Parc Natural de Garraf (matoll) i la segona en les Muntanyes de Prades (bosc), dos ecosistemes típicament mediterranis. Les dues espècies van emetre terpens, però només es va detectar una emissió significativa d’isoprè en E. multiflora. Les emissions d'isoprenoides van augmentar amb la temperatura de l'aire i generalment van disminuir a mesura que augmentava la humitat del sòl. Les emissions de terpens van augmentar sinèrgicament a causa de l'estrès per calor i la sequera a l'estiu. La fertilització amb nitrogen no va afectar significativament l'emissió de isoprè, però va augmentar significativament les emissions totals de terpens i va disminuir la seva diversitat. Per als sòls dels mateixos ecosistemes de matolls i boscos d'alzines, els de matolls van mostrar concentracions totals de COVs més altes que els boscos. Les concentracions de metanol, àcid acètic, formaldehid, etanol i acetaldehid van ser els compostos dominants en ambdós ecosistemes. La temperatura del sòl i el contingut d'aigua, el flux de CO2 i l'activitat enzimàtica van ser les millors variables explicatives de la variació en les concentracions de COVs del sòl en els dos ecosistemes: hi va haver una associació més forta entre la concentració de compostos dominants, excepte el formaldehid, amb la temperatura del sòl i / o el flux de CO2 que amb el contingut d'aigua del sòl. L'activitat dels enzims que degraden el C i el N es va associar positivament amb la concentració de COVs, segons l'ecosistema, i es va correlacionar constantment amb un alt contingut d'aigua en el sòl. També vaig analitzar una gespa mediterrània amb arbres de Pinus pinea L. Vaig quantificar l'intercanvi d'isoprenoides entre el sòl (amb fullaraca) i l'atmosfera al llarg d'un gradient horitzontal des dels troncs de Pinus pinea. Les emissions d'isoprenoides van ser majors i més diverses, i també es poden estimar aproximadament pel pes sec de la fullaraca a prop del tronc, on la fullaraca d'acícules era més densa. Les taxes d'intercanvi es van correlacionar positivament amb la temperatura del sòl i negativament amb la humitat del sòl a la zona de gespa a cel obert. En conclusió, es poden esperar més emissions de COVBs a causa dels augments en les emissions foliars, i els intercanvis i concentracions de sòls com a resultat del canvi climàtic a la regió mediterrània.
Los compuestos orgánicos volátiles biogénicos (COVBs) juegan un papel importante en la ecología y la química atmosférica. Las emisiones de éstos por los ecosistemas terrestres son debidas principalmente a las plantas y están muy influenciadas por las variaciones en las variables ambientales y, por lo tanto, se ven afectadas por el aumento del cambio ambiental global. Sin embargo, estas emisiones y sus influencias no son bien conocidas en los ecosistemas mediterráneos. Si bien los COVBs del suelo aparentemente desempeñan un papel menor en la química atmosférica, debido a su fracción generalmente baja con respecto a las emisiones totales de los ecosistemas de tipo mediterráneo, desempeñan un papel ecológico importante en los procesos del suelo. Muchos estudios anteriores sobre COVs del suelo han analizado los flujos, mientras que las concentraciones reales de COVs en los suelos de los ecosistemas mediterráneos no se han considerado. En este trabajo, realizo el seguimiento de experimentos de manipulación ambiental en ecosistemas típicos mediterráneos para estudiar los intercambios de COVs, incluidas las emisiones de las plantas, y los intercambios y concentraciones de suelos, y los factores que los determinan. El arbusto Erica multiflora L., especie abundante en matorrales mediterráneos y el árbol Quercus ilex L., especie dominante en muchos bosques mediterráneos fueron las especies estudiadas, la primera en el Parque Natural del Garraf (matorral) y la segunda en Les Muntanyes de Prades (bosque), dos ecosistemas típicamente mediterráneos. Ambas especies emitieron terpenos, pero sólo se detectó una emisión significativa de isopreno en E. multiflora. Las emisiones de isoprenoides aumentaron con la temperatura del aire y generalmente disminuyeron a medida que aumentaba la humedad del suelo. Las emisiones de terpenos aumentaron sinérgicamente debido al estrés por calor y la sequía en verano. El fertilizante nitrogenado no afectó significativamente la emisión de isopreno, pero aumentó significativamente las emisiones totales de terpenos y disminuyó su diversidad. Para los suelos de los mismos ecosistemas de matorrales y bosques de encinas, los de matorrales mostraron concentraciones totales de COVs más altas que los bosques. Las concentraciones de metanol, ácido acético, formaldehído, etanol y acetaldehído fueron los compuestos dominantes en ambos ecosistemas. La temperatura del suelo y el contenido de agua, el flujo de CO2 y la actividad enzimática fueron las mejores variables explicativas de la variación en las concentraciones de COVs del suelo en los dos ecosistemas: hubo una asociación más fuerte entre la concentración de compuestos dominantes, excepto el formaldehído, con la temperatura del suelo y / o el flujo de CO2 que con el contenido de agua del suelo. La actividad de las enzimas que degradan el C y el N se asoció positivamente con la concentración de COVs, según el ecosistema, y se correlacionó constantemente con un alto contenido de agua en el suelo. También muestreé un césped mediterráneo con árboles de Pinus pinea L. Cuantifiqué el intercambio de isoprenoides entre el suelo (con hojarasca) y la atmósfera a lo largo de un gradiente horizontal desde los troncos de Pinus pinea. Las emisiones de isoprenoides fueron mayores y más diversas, y también pueden estimarse aproximadamente por el peso seco de la hojarasca cerca del tronco, donde la hojarasca de acículas era más densa. Las tasas de intercambio se correlacionaron positivamente con la temperatura del suelo y negativamente con la humedad del suelo en la zona de césped en cielo abierto. En conclusión, se pueden esperar mayores emisiones de COVBs debido a los aumentos en las emisiones foliares, y los intercambios y concentraciones en los suelos como resultado del cambio climático en la región mediterránea.
Biogenic volatile organic compounds (BVOCs) play important roles in ecology and atmospheric chemistry. Their emissions from terrestrial ecosystems are driven mainly by plants, and are greatly influenced by the variations in environmental variables and therefore are altered by increasing global environmental change (GEC). However, these emissions and their influences are not well known in natural Mediterranean ecosystems. While soil BVOCs apparently play a minor role in atmospheric chemistry, owing to their usually low fraction with respect to the total ecosystem emissions in Mediterranean-type ecosystems, they play important ecological roles in soil processes. Much previous studies on soil VOCs have looked at fluxes, while the actual VOC concentrations in soils from Mediterranean ecosystems have never been considered. In this work, I carry out the monitoring of environmental manipulation experiments in typical Mediterranean ecosystems to study the exchanges of VOCs, including emissions from plants, and exchanges and concentrations of soils, and their possible drivers. The shrub Erica multiflora L. abundant species in Mediterranean shrublands and the tree Quercus ilex L. dominant species in many Mediterranean forests were the species studied, the former in the Garraf Natural Park (shrubland) and the latter in Les Muntanyes de Prades (forest), two typically Mediterranean ecosystems. Both species emitted terpenes, but a significant emission of isoprene was only detected from E. multiflora. Isoprenoid emissions increased with air temperature and generally decreased as the amount of soil moisture increased. Terpene emissions increased synergistically due to heat stress and drought in summer. Nitrogenous fertilizer did not significantly affect the emission of isoprene, but it significantly increased the total emissions of terpenes and decreased their diversity. The results suggest that higher isoprenoid emissions can be expected as the Mediterranean region becomes warmer and drier over the next few decades and that N deposition could further stimulate these emissions. For the soils of the same shrubland and holm oak forest ecosystems, those of shrubland showed higher total VOC concentrations than forest. The concentrations of methanol, acetic acid, formaldehyde, ethanol, and acetaldehyde were the dominant compounds in both ecosystems. Soil temperature and water content, CO2 efflux, and enzyme activity were the best explanatory variables for variation in soil VOC concentrations in the two ecosystems: there was a stronger association between concentration of dominant compounds, except formaldehyde, with soil temperature and/or CO2 efflux than with soil water content. Activity of C- and N-degrading enzymes was positively associated with the concentration of VOCs, depending on ecosystem, and consistently correlated with high soil water content. In the holm oak forest soils, net photosynthetic rate (A) was positively correlated with soil concentration of monoterpenes. These results show that soil VOC concentrations in these Mediterranean ecosystems are driven by soil temperature and water content, and microbial activity, in combination with ecosystem plant activity. I also analyzed a Mediterranean turf with Pinus pinea L. trees. I quantified the exchange of isoprenoids between soil (with litter) and atmosphere along a horizontal gradient from the trunks of Pinus pinea. Isoprenoid emissions were greatest and most diverse, and also can be roughly estimated by litter dry weight near the trunk, where the needle litter was denser. Irregular emission and adsorption of isoprenoids with low exchange rates were recorded, and exchange rates were correlated positively with soil temperature and negatively with soil moisture in open turf. In conclusion, higher BVOC emissions can be expected owing to the increases in foliar emissions, and exchanges and concentrations of soils, and N deposition will also further stimulate these emission trends by increasing foliar isoprenoid emissions in the warmer and drier conditions predicted for the coming decades in the Mediterranean region.
Universitat Autònoma de Barcelona. Programa de Doctorat en Ecologia Terrestre

This dissertation investigates unexplained vapor intrusion field data sets that have been observed at hazardous waste sites, including: 1) non-linear soil gas concentration trends between the VOC source (i.e. contaminated groundwater plume) and the ground surface; and, 2) alternative pathways that serve as entry points for vapors to infiltrate into buildings and serve to increase VOC exposure risks as compared to the classic vapor intrusion model, which primarily considered foundation cracks as the route for vapor entry. The overall hypothesis of this research is that theoretical knowledge of fate and transport processes can be systematically applied to vapor intrusion field data using a multiple lines of evidence approach to improve the science-based understanding of how and when vapor intrusion exposure risks will pose increased exposure risk; and, ultimately this knowledge can be used to develop policies that reduce exposure risks. The first objective of this research involved numerical modeling, field sampling and laboratory tests to investigate which factors influence soil gas transport within the subsurface. Combining results of all of these studies provide improved understanding of which factors influence VOC fate and transport within the subsurface. Importantly, the results demonstrate a non-linear trend between the VOC source concentration in the subsurface and the ground surface concentration at the study site, which disagrees with many vapor intrusion conceptual models. Ultimately, the source concentration may not be a good predictor of shallow soil gas concentrations. Laboratory tests described the effect of soil characteristics such as the soil water content on VOC vapor diffusion. The numerical model was able to explain specific conditions that could not be described by the field and laboratory data alone. A paper was published that summarizes the major outcomes from this objective (Pennell et al, 2016). The second objective of this research investigated preferential pathways for VOC vapor migration into buildings. Sewer systems can act as important pathways for vapor intrusion. The research objective is to evaluate conditions that increase the potential for inhalation exposure risks via vapor intrusion thorough sewer systems into indoor spaces. A field study was conducted in California over a 4-year period to investigate the spatial and temporal variability of alternative pathways (e.g. aging infrastructure piping systems) within the context of vapor intrusion exposure risks. A paper was published that summarizes the major outcomes from the field study (Roghani et al. 2018). The final research objective involved the development of a numerical model to describe VOC fate and transport within a sewer system. The numerical model predicts VOC mass transport. The model results were compared to the field data and provides insight about the role preferential pathways play in increasing VOC exposure risks.

The maintenance or replacement of deteriorated pipes and culverts is a constant and significant concern for municipalities and transportation agencies in the United States (Donaldson and Wallingford, 2010). Trenchless technologies and especially the Cured-in-place pipe (CIPP) method have become increasingly common ways to preserve infrastructures owing to their feasibility, cost-effectiveness, and fewer social impacts (Jung and Sinha, 2007). Therefore, there is a growing need to understand the direct and indirect effects of pipeline rehabilitation activities on the environment. Nearly all past CIPP studies have focused on its mechanical properties, and its environmental impacts are poorly investigated and documented (Allouche et al. 2012). Sewer pipelines and storm-water culverts are administered by municipalities and transportation agencies who bear the responsibility for rehabilitation and renewal of these infrastructures. In consequence, they rarely allow sampling and research projects in the field due to liability issues. This is a main obstacle to conducting comprehensive, precise, and unbiased research on CIPP environmental impacts and to date, the degree of relevant health effects and related environmental impacts have remained unknown. Numerous building indoor air contamination incidents indicate that work is needed to understand the magnitude of styrene emission from CIPP sanitary sewer repairs. The main goal of this study was to better comprehend Volatile Organic Compounds emission at three CIPP sanitary sewer installation sites in one U.S. city. Results showed that CIPP chemical emissions may be a health risk to workers and nearby building inhabitants. Additional testing and investigations regarding chemical emissions from CIPP should be commissioned to fill in the environmental and public health knowledge gaps. The acute and chronic chemical exposure risks of CIPP chemical steam constituents and styrene to sensitive populations should be further examined. Other goals of this study were to estimate the magnitude of solid waste generated as well as the amount of certain criteria air pollutants and greenhouse gases emitted from onsite heavy equipment for both CIPP and open-cut sites in a U.S city. The results indicated that the amount of open-cut related solid waste, criteria air pollutants, and greenhouse gases were greater than those during CIPP activities. Additional work is needed to quantify pollutant emissions from CIPP and open-cut activities and consider emissions from a cradle-to-grave standpoint.

The maintenance or replacement of deteriorated pipes and culverts is a constant and significant concern for municipalities and transportation agencies in the United States (Donaldson and Wallingford, 2010). Trenchless technologies and especially the Curedin- place pipe (CIPP) method have become increasingly common ways to preserve infrastructures owing to their feasibility, cost-effectiveness, and fewer social impacts (Jung and Sinha, 2007). Therefore, there is a growing need to understand the direct and indirect effects of pipeline rehabilitation activities on the environment. Nearly all past CIPP studies have focused on its mechanical properties, and its environmental impacts are poorly investigated and documented (Allouche et al. 2012). Sewer pipelines and storm-water culverts are administered by municipalities and transportation agencies who bear the responsibility for rehabilitation and renewal of these infrastructures. In consequence, they rarely allow sampling and research projects in the field due to liability issues. This is a main obstacle to conducting comprehensive, precise, and unbiased research on CIPP environmental impacts and to date, the degree of relevant health effects and related environmental impacts have remained unknown.

Numerous building indoor air contamination incidents indicate that work is needed to understand the magnitude of styrene emission from CIPP sanitary sewer repairs. The main goal of this study was to better comprehend Volatile Organic Compounds emission at three CIPP sanitary sewer installation sites in one U.S. city. Results showed that CIPP chemical emissions may be a health risk to workers and nearby building inhabitants. Additional testing and investigations regarding chemical emissions from CIPP should be commissioned to fill in the environmental and public health knowledge gaps. The acute and chronic chemical exposure risks of CIPP chemical steam constituents and styrene to sensitive populations should be further examined.

Thesis (MSc)--Stellenbosch University, 2012.
ENGLISH ABSTRACT: The need to analyse and detect volatile organic compounds (VOCs) at trace levels has led to the development of specialized sample preparation techniques. The requirement for trace analysis of VOCs stems from the negative effects they have on the environmental and human health. Methods for the analysis of non-polar VOCs commonly found as trace contaminants in water and analysis of more polar oxygenated compounds commonly found in zero-VOC water-based paints were developed. Solid phase micro extraction (SPME) was employed and extraction of the majority of the target analytes could be achieved at levels below 0.3 μg.l-1. In an attempt to further improve the detection of these two target analyte groups, novel materials based on poly(dimethyl siloxane) (PDMS) were investigated as possible extraction phases for VOCs, with the focus specifically on the analysis of the polar analytes in paint. Conventional free radical polymerization was used to synthesize poly(methyl methacrylate-graft-poly(dimethyl siloxane) (PMMA-g-PDMS), poly(methacrylic acid)-graft-poly(dimethyl siloxane) (PMAA-g-PDMS), polystyrene-graftpoly( dimethyl siloxane) (PSty-g-PDMS) and poly(butyl acrylate)-graft–poly(dimethyl siloxane) (PBA-g-PDMS). These polymers have a copolymer functionality which presents a series of different polarities. The MMA-g-PDMS and MAA-g-PDMS as well as the homopolymers were electrospun into nanofibers. The low glass transition temperature and molecular weight of the PBAg- PDMS meant that this polymer could not be electrospun. Scanning electron microscopy (SEM) was used to study the fiber morphology of the electrospun fibers and the non-beaded fibers were further investigated. Polyacrylonitrile-graft-poly(dimethyl siloxane) (PAN-g-PDMS) previously synthesized and electrospun by another member of the group were also investigated for use as possible extraction material in volatile analysis. The thermal stability of the nanofibers at 200°C was studied using thermal gravimetric analysis (TGA). This property is important since after the target analytes are extracted using the nanofibers, elevated temperatures are used to thermally desorp the volatile analytes from the extraction materials prior to GC analysis. The PAN-g-PDMS, MMA-g-PDMS and PMMA showed no significant weight loss during thermal evaluation, however, it was observed that the PMMA and PMMA-g-PDMS nanofibers looses their nanostructure and that the PAN-g-PDMS nanofibers changes colour from white to yellow to rust brown. The polymers based on MAA showed weight losses of more than 10% after one hour of exposure to the elevated temperatures, but the nanostructure remained intact. The PAN-g-PDMS, PMAA-g-PDMS and PMAA nanofibers were evaluated as possible extraction materials for VOC analysis. The nanofibers were evaluated using a similar approach to that of stir bar sorptive extraction (SBSE). Headspace sorptive extraction (HSSE) using a commercially available PDMS stir bar and the novel materials were used to evaluate the extraction efficiency of the different materials. The optimized extraction method developed using SPME were employed for the extraction using the nanofibers and PDMS stir bar. It was noted that the nanofibers lose their extraction capabilities during the first extraction/desorption cycle possibly due to thermal degradation therefore each of the materials can only be used in a single extraction. The majority of the non-polar analytes were extracted using the nanofibers at levels of 500 μg.l-1, however it was noted that the commercially available SPME extraction materials and the PDMS stir bar had superior extraction efficiencies for the specific target analytes. In the evaluation of the nanofibers for extraction of the more polar oxygenated analytes it was noted that 2-Ethylhexylacrylate was the only analyte to be extracted by all of the materials. The PAN-g-PDMS extracted three of the four analytes at levels of 100 μg.l-1. At lower analyte concentrations of 10 μg.l-1 only two of the four acrylate compounds were detected using the PAN-g-PDMS nanofibers. Ethyl acrylate was not extracted by any of the novel materials, whereas in SPME using the CAR/PDMS fiber, the LOD was determined to be below 1 μg.l-1. Although these materials were not superior to the commercially available phases, this is only the case for the specific target analytes analyzed.
AFRIKAANSE OPSOMMING: Die behoefte vir die analiese van vlugtige organiese verbindings (VOS) op spoorvlak, het gelei tot die ontwikkeling van gespesialiseerde monster voorbereidingstegnieke. Die vereiste vir die spoor analiese van die VOS het ontstaan uit die negatiewe uitwerking wat hierdie stowwe het op die omgewing en menslike gesondheid. Metodes vir die analiese van nie-polêre VOS wat algemeen voorkom as spoorkontaminante in water en polêre suurstofryke verbindings wat algemeen voorkom in nul-VOS water-gebaseerde verf was ontwikkel. Soliede fase mikro-ekstraksie (SFME) was gebruik, en die ekstraksie van die meerderheid van die teikenstowwe kon gedoen word op vlakke laer as 0,3 μg.l-1. In 'n poging om die opsporing van hierdie twee teiken analietgroepe verder te verbeter, is nuwe materiale gebaseer op polidimetielsiloksaan (PDMS), ondersoek as moontlik ekstraksiefases vir VOS, met die fokus spesifiek op die analiese van die polêre stowwe in verf. ’n Konvensionele vrye radikaal polimerisasieproses was gebruik om poli (metiel- metakrilaat)-entpoli( dimetielsiloksaan) (PMMA-g-PDMS), poli(metakrilaatsuur)-ent–poli (dimetielsiloksaan) (PMAA-g-PDMS), polistireen-ent-poli(dimetielsiloksaan) (PSty-g-PDMS) en poli(butielakrilaat)- ent-poli(dimetielsiloksaan) (PBA-g-PDMS) te sintetiseer. Hierdie ko-polimere het 'n kopolimeer funksionaliteit wat 'n reeks van verskillende polariteite bied. Die MMA-g-PDMS en MAA-g-PDMS sowel as die homopolimere was ge-elektrospin in orde om nanovesels te vorm. Die lae glasoorgangstemperatuur en molekulêre gewig van die PBA-g-PDMS het beteken dat hierdie polimeer nie elektrospin kon word nie. Skandeerelektronmikroskopie (SEM) was gebruik om die veselmorfologie van die ge-elektrospinde vesels te bestudeer en die nanovesels wat ’n eweredige oppervlak gehad het, was verder ondersoek. Poliakrilonitriel-ent-poli(dimetielsiloksaan) (PAN-g- PDMS) wat voorheen gesintetiseer en ge-elektrospin was deur 'n ander lid van die groep is ook ondersoek vir gebruik as moontlik ekstraksiemateriaal vir die analiese van vlugtige stowwe. Die termiese stabiliteit van die nanovesels was by 200°C bestudeer met behulp van ‘n termiese gravimetriese analiese (TGA) instrument. Hierdie eienskap is belangrik, aangesien die teikenstowwe by hoë temperature van die nanovesels gedesorbeer word voor die GC-analiese. Die PAN-g-PDMS, MMA-g-PDMS en PMMA het geen beduidende gewigsverlies tydens termiese evaluering gehad nie, alhoewel dit egter waargeneem was dat die PMMA en PMMA-g-PDMS nanovesels hulle nanostruktuur verloor en dat die PAN-g-PDMS nanovesels se kleur verander van wit na geel na roesbruin gedurende die termiese analiese. Die polimere wat gebaseer was op MAA het ’n gewigs-verlies van meer as 10% getoon na 'n uur van blootstelling aan die verhoogde temperature, maar die nanostruktuur het ongeskonde gebly. Die PAN-g-PDMS, PMAA-g-PDMS en PMAA nanovesels was geëvalueer as moontlike ekstraksiemateriale vir VOS-analiese. Die nanovesels was geëvalueer met 'n soortgelyke benadering tot dié van “stir bar“ sorpsie ekstraksie (SBSE). Bo-ruimte sorpsie ekstrasie is gebruik om die ekstraksie-doeltreffendheid van die verskillende materiale (kommersiële PDMS en nanovesels) te evalueer. Die geoptimaliseerde ekstraksiemetode ontwikkel in SFME was gebruik vir die ekstraksie van die VOS met die nanovesels en die PDMS “stir bar“. Dit was waargeneem dat die nanovesels hul ekstraksievermoë verloor tydens die eerste ekstraksie/desorpsie siklus, moontlik as gevolg van termiese degradasie dus, kon die materiale slegs ‘n enkele maal gebruik word vir die ekstraksie. Die meerderheid van die nie-polêre stowwe was ge-ëkstraeer deur gebruik te maak van die nanovesels op vlakke van 500 μg.l -1, maar die kommersieel beskikbare SFME ekstraksie materiale en die PDMS “stir bar“ se ekstraksie-doeltreffendheid vir die spesifieke stowwe was beter. In die evaluering van die nanovesels vir die ekstraksie van die meer polêre suurstofryke stowwe was daar waargeneem dat 2- etielheksielakrilaat die enigste analiet was wat ge-ëkstraeer was deur al die materiale. Die PAN-g- PDMS kon drie van die vier polêre stowwe op vlakke van 100 μg.l-1 opspoor. By laer analietkonsentrasies van 10 μg.l-1 kon slegs twee van die vier akrilaat verbindings opgespoor word deur gebruik te maak van hierdie nanovesels. Etielakrilaat was nie ge-ëkstraeer deur enige van die nuwe materiale nie, terwyl in SFME met die gebruik van die CAR/ PDMS vesel, die analiet op vlakke onder 1 μg.l-1 opgespoor kon word. Alhoewel hierdie nuwe materiale nie beter is as die kommersieel beskikbare ekstraksiemateriale nie is dit net die geval vir die spesifieke teiken analietgroepe wat ondersoek was in hierdie studie.

With the increasing time people spend indoors, the indoor environment quality draws more and more attention. The concentration of indoor pollutants is usually much higher than outdoors, in which volatile organic compounds (VOCs) and mold/mildew are both major pollutants and cause many health problems to residents. Efforts devoted from academy and industry to protecting people from indoor environment problems are apparently not sufficient. Photocatalysts, such as TiO2, WO and ZnO, can absorb light photons and react with O2 and H2O to generate highly oxidative radicals, which can oxidize VOCs and disinfect microorganisms. Recently, this photocatalytic oxidation (PCO) technology has been intensively studied to reduce VOCs and disinfect bacteria in the indoor environment. Few papers address the indoor mold/mildew problem, and this research therefore endeavors to do so. The objectives are to evaluate the effectiveness of PCO technology to resist mold/mildew growth and prevent VOC emission from building materials under either UV or visible light irradiation. The models, including linear regression, logistic regression, and numerical model, are also built for interpreting experimental results and for predicting performance in application. The mold/mildew resistance of different PCO gels was examined using accelerated mold/mildew growth agar plate tests. These gels included TiO2 only and TiO2 in combination with H2O2 and with Ag. Without the application of PCO gels, no mold/mildew inhibition was observed from UV (365 nm) or visible light. Under UV light irradiation, the TiO2 gel achieved complete mold/mildew inhibition. Without light, a 12-day delay of mold growth was obtained using the Ag-TiO2/H2O2 gel. Under visible light irradiation, the Ag-TiO2/H2O2 gel was also the most effective PCO gel with a 8-day delay of mold growth, which, however, was shorter than the same gel in the condition of no light with a 10-day delay due to the light-induced deterioration of the Ag-TiO2. The reduction of VOC emission from PCO gel (TiO2 gel and Ag-TiO2/H2O2 gel) coated building materials under UV or visible light irradiation was also confirmed by small chamber tests (the Ag-TiO2/H2O2 gel with above 50% reduction of total VOC emission). A linear model was obtained for the Ag-TiO2/H2O2 gel in the condition of no light, with respect to the correlation between the delay of mold growth and the gel ingredients. A logistic model was created for predicting the probability of mold growth on different TiO2 gels with different UV light exposure time at different intensities. A numerical model was developed with better accuracy than the previous one for VOC emission from PCO gel coated building materials. This study showed that the PCO gel might be a promising multifunctional material in resisting mold/mildew growth and preventing VOC emission in the indoor environment (The TiO2 gel for complete mold/mildew inhibition and the Ag-TiO2/H2O2 gel for delay of mold growth in emergency situations and reduction of VOC emission from building materials). More stable Ag-TiO2 or other visible-light-driven photocatalysts are needed in future research because of the deterioration of the current one.

Emissions from Particles and Volatile Organic Compounds (VOC) in Falun.-How is the emission divided between particles and VOC?

This study investigates the air quality in Falun, a small city in central Sweden, with a focus on particles and volatile organic compounds (VOC). Falun is located in a valley which makes it sensitive to inversions, when the vertical mixing of air over the city is prevented. When this happens emissions over the city can stay for days and the pollution levels can be high. The report is based upon a literature review, calculation of emissions from traffic and a survey of industrial emissions. Emission of VOCs can be dangerous to people and contributes to the production of ground- level ozone. Particles can be a carrier for other dangerous compounds. The result shows that high pollution levels caused by inversions can happen. The temperature, wind and temperature differences show that inversions during the winter months are possible up to half of the time. Emissions from cars and industries are a problem. The municipality forced to control air pollution and in Swedish law there is a threshold value for both particles and the volatile organic compounds benzene. Spreading of pollution in air in Falun is centered around the emission sourses. Because it´s hard to prevent inversions, the municipality must focus on reducing emission of pollutants. This can be done through road planning and diverting traffic to other routes around the city.

This thesis reports the investigations of sheep wool’s ability to sorb volatile and very volatile organic compounds (v/VOCs). Indoor air quality and occupants health can be adversely affected by the presence of even low gaseous concentrations of v/VOCs. Sheep wool’s fibres, with their keratinous chemical functionalities, provide platforms for sorption of the said compounds. Wools from different breeds of sheep are studied with regards to the sorption of four volatile organic compounds in their gaseous state, which represents a wide range of polarity and basic chemical diversity: formaldehyde, toluene, limonene and dodecane. A gas-tight set-up was constructed and analytical techniques were optimised. It was found that there is variation between the different wool types in addition to difference between scoured and unscoured wools. Total sorption capacity of formaldehyde is also examined, with variations opposing the trend seen for the sorption of the more non-polar VOCs at low concentrations. Sorption patterns were studied with respect to increasing concentrations. Characteristics of the different wool types are reported and linked to the observed sorption behaviour. Moisture uptake is studied across different wool types and the use of the Vrentas-Vrentas mathematical model is discussed. The mean cluster size of water molecules in the wool fibres is compared. The sorption kinetic behaviour of the wool fibres is analysed using the Parallel Exponential Kinetic model, and the sorption parameters were used to calculate the modulus of the wool fibres. Chemical and mechanical modifications along with the use of additives are studied to enhance wool’s sorption ability. Adding polar functionalities onto the fibres’ surface hinders total sorption capacity of formaldehyde and the sorption of all four v/VOCs at low concentrations. Adding a large non-polar functionality also hinders total sorption capacity of formaldehyde, but increases the sorption at low concentrations of non-polar compounds without reducing the sorption of polar formaldehyde. Ball milling increases surface area and the sorption of all four compounds at low concentrations. Carbon fibre as an additive excels at the sorption of non-polar compounds, whereas a coating of chitosan increases the total sorption capacity of formaldehyde without effecting the sorption patterns of any of the v/VOCs at low concentrations. The effect of the modifications on other fibre properties is also reported.

This thesis concerns the development of semiochemical identification expertise and methodology at the University of Pretoria. The Eucalyptus snout beetle Gonipterus scutellatus was used as a model insect in developing these methods, firstly because it is a known pest in the Eucalyptus forestry industry of South Africa. Secondly, nothing is known about its chemical ecology and lastly, it is a relatively large insect that is easily worked on. Three main techniques were used namely: Electroantennography (EAG), Gas Chromatography Electroantennography Detection (GC-EAD) and Gas Chromatog- raphy Mass Spectrometry (GC-MS). EAG was used to difierentiate and identify certain Eucalyptus species that were expected to contain compounds that may function as either kairomones or allomones for G. scutellatus. The EAG process revealed that G. scutellatus responds more intensely to damaged Eucalyptus leaves as compared to undamaged leaves. The crushed foliage of the known hosts Eucalyptus globulus and E. viminalis gave larger responses than the crushed foliage from a known non-host E. citriodora. We sampled the volatiles from the crushed foliage of these three species and tentatively identified sixteen compounds from the E. globulus volatile profile that was antennally active for G. scutellatus females. The presence of these volatiles were subsequently investigated for E. viminalis and E. citriodora. The green leaf volatiles, (Z)-3 hexenyl acetate, (Z)-3-hexen-1-ol and (E)-2-hexenal and aromatic compounds, 2-phenylethanol, benzyl acetate and ethylphenylacetate often gave larger responses than the terpenes such as α-pinene, β-pinene and camphene. Crushed E. globulus leaves contained 2-phenyl ethanol, benzyl acetate, ethylphenylacetate, eucalyptol, α-pinene, (Z)-3 hexenyl acetate, (Z)-3-hexen-1-ol and (E)-2-hexenal that were antennally active. The E. viminalis profile had very little 2-phenylethanol and virtually no benzyl acetate. The E. citriodora volatile profile contained very little (Z)-3-hexen-1-ol, (E)-2-hexenal, 2-phenylethanol, benzyl acetate and ethylphenylacetate. These compounds may influence the host selection behaviour of G. scutellatusfemales. These volatiles can be tested in a behavioural bioassay in order to determine their effect on the Eucalyptus snout beetle G. scutellatus.
Dissertation (MSc)--University of Pretoria, 2010.
Chemistry
unrestricted

Flüchtige organische Verbindungen (Volatile organic compounds (VOC)) sind ubiquitär vorkommende kohlenstoffhaltige Substanzen. Untersuchungen haben relevante VOC-Konzentrationen im Inneren von Gebäuden nachgewiesen. Da der Innenraum zum typischen Aufenthaltsort des modernen Menschen geworden ist, sind diese Schadstoffe in das Interesse der Forschung gerückt. Kinder reagieren unter Schadstoffexposition besonders sensibel, denn viele wichtige Organsysteme befinden sich noch in ihrer Entwicklung. In der vorliegenden Arbeit wurden Leipziger Daten der LISA-Studie („Einfluss von Lebensbedingungen und Verhaltensweisen auf die Entwicklung von Immunsystem und Allergien im Ost-West-Vergleich“) hinsichtlich möglicher Effekte einer VOC-Exposition auf Erkrankungen der Kinder im 4. Lebensjahr analysiert. Bei der LISA-Studie handelt es sich um eine multizentrische prospektive Geburts-Kohortenstudie, in die von November 1997 bis Januar 1999 insgesamt 3097 gesunde und reife Neugeborene deutscher Herkunft mit einem Geburtsgewicht > 2500 g rekrutiert wurden. Die Berechnungen der vorliegenden Arbeit erfolgten mit VOC-Messwerten um den 3. Geburtstag der Kinder. Die jeweiligen logistischen Regressionsmodelle wurden auf das Geschlecht, die atopische Familienanamnese, eine passive Tabakrauchexposition, das Aufstellen neuer Möbel im Kinderzimmer, Renovierungen und die Erneuerung des Fußbodenbelags in der Wohnung adjustiert. Es ließen sich VOC bestimmen, die bei Konzentrationserhöhungen eine erhöhte Chance für eine akute Bronchitis zur Folge hatten. Als Risikofaktor einer akuten Bronchitis ließ sich außerdem die Erneuerung des Fußbodenbelags in der Wohnung ermitteln. Während sich für eine akute Bronchitis in Abhängigkeit der VOC-Konzentration erstmals eine Dosis-Wirkungs-Kurve ableiten ließ, war dies für allergische Erkrankungen nicht möglich. Weitere Untersuchungen sind notwendig um Pathomechanismen der VOC-Einwirkungen auf den kindlichen Organismus aufzuklären.