Liquid-liquid Phase Separation and Efflorescence in Mixed Organic/inorganic Aerosol Particles PDF Download

Author: Viorela-Gabriela Ciobanu
Publisher:
ISBN:
Category :
Languages : en
Pages : 164

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Author: David L. Topping
Publisher: John Wiley & Sons
ISBN: 1119625653
Category : Science
Languages : en
Pages : 372

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INTRODUCTION TO AEROSOL MODELLING Introduction to Aerosol Modelling: From Theory to Code An aerosol particle is defined as a solid or liquid particle suspended in a carrier gas. Whilst we often treat scientific challenges in a siloed way, aerosol particles are of interest across many disciplines. For example, atmospheric aerosol particles are key determinants of air quality and climate change. Knowledge of aerosol physics and generation mechanisms is key to efficient fuel delivery and drug delivery to the lungs. Likewise, various manufacturing processes require optimal generation, delivery and removal of aerosol particles in a range of conditions. There is a natural tendency for the aerosol scientist to therefore work at the interface of the traditional academic subjects of physics, chemistry, biology, mathematics and computing. The impacts that aerosol particles have are linked to their evolving chemical and physical characteristics. Likewise, the chemical and physical characteristic of aerosol particles reflect their sources and subsequent processes they have been subject to. Computational models are not only essential for constructing evidence-based understanding of important aerosol processes, but also to predict change and impact. Whilst existing textbooks provide an overview of theoretical frameworks on which aerosol models are based, there is a significant gap in reference material that provide training in translating theory into code. The purpose of this book is to provide readers with exactly that. In following the content provided in this book, you will be able to reproduce models of key processes that can either be used in isolation or brought together to construct a demonstrator 0D box-model of a coupled gaseous-particulate system. You may be reading this book as an undergraduate, postgraduate, seasoned researcher in the private/public sector or as someone who wishes to better understand the pathways to aerosol model development. Wherever you position yourself, it is hoped that the tools you will learn through this book will provide you with the basis to develop your own platforms and to ensure the next generation of aerosol modellers are equipped with foundational skills to address future challenges in aerosol science.

Author: Emily Jean Ott
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Aerosol particles can have a variety of compositions which determines their origin and their phase transitions. They can exist in the atmosphere where they are emitted from a variety of natural and anthropogenic sources. Aerosol particles can impact the climate directly though interacting with radiation or indirectly by nucleating cloud droplets and the clouds interacting with the sun. Aerosols can also impact health through the respiratory system. Additionally, aerosols can be used for synthetic purposes where they are created purposely for pharmaceutical or material creation along with many other applications. Understanding the factors that influence phase transitions that a particle may undergo is a prerequisite to understanding both atmospheric aerosol and synthetic aerosol. Several of these factors are investigated. First, the impact of the average ratio of oxygen to carbon (O:C) atoms in the organic molecules through the addition of sucrose to aerosol particles is studied using optical microscopy. A variety of organic molecules and salts combinations which are able to undergo phase separation were studied. The organic/inorganic mixtures exhibit a mixture both high and low separation relative humidities. Then sucrose was added until the particles no longer exhibit phase separation. Particles with higher separation relative humidities in the absence of sucrose required larger quantities of sucrose in order to inhibit phase separation. Additionally, phase separation was seen at higher O:C values than published previously, showing that while average O:C is a good indicator of phase separation, the precise composition of the particles is more important. The morphology of polymer/polymer aerosol particles according to their size was determined. In agreement with previous work, large particles undergo liquid-liquid phase separation while small particles remain homogeneous. Polyethylene glycol with dextran was used as well as polystyrene sulfonate with polyvinyl alcohol. Both of these systems inhibited phase separation at small sizes. To understand the size dependent morphology of polymer/polymer systems, different molecular weight mixtures of the polymers were studied. As the molecular weight of the polymers increased, smaller and smaller aerosol particles were able to undergo phase separation. This was further confirmed with a simple model based on the equations of phase separation and Flory-Huggins theory of a binary system which also showed the decrease in the size of the smallest phase separated particle as the molecular weight of the polymers increase in the size regime studied. The project created novel polymer materials and investigated the phase separation of polymer/polymer systems in confinement. The phase separation of submicron aerosol particles with different salts was investigated to determine the influence of different anions on the size dependent morphology of aerosol particles. The ammonium, sodium, chloride and sulfate ions were used. TEM was used to determine that sodium salts transition to homogenous particles at smaller sizes than their comparable ammonium salt. This difference is likely due to the softness of the ammonium ion when compared to the hardness of the sodium ion. This study provides insights into the size dependent morphology of sea spray aerosol may differ from that of continental aerosol in addition to increasing our understanding of how cations and anions impact phase transitions under confinement. These studies combined increase knowledge of confined phase transitions. While the O:C ratio has been studied before, the importance of the actual composition over the average O:C ratio has now been shown which is useful in understanding atmospheric aerosol particles. The presence of a size dependent morphology for polymer-polymer systems has been shown and modeled in addition to the development of novel polymeric materials. The phase separation differences between ammonium containing aerosols and sodium containing aerosols provides key insights into the differences between continental aerosol and sea spray aerosol in addition to contributing new information about the importance of cations in liquid-liquid phase separation of confined systems. Through these studies both atmospheric aerosol and synthetic aerosol are now better understood.

Author: Yue Zhang
Publisher: American Chemical Society
ISBN: 0841299293
Category : Science
Languages : en
Pages : 176

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The uncertainties in the aerosol effects on radiative forcing limit our knowledge of climate change, presenting us with an important research challenge. Aerosols in Atmospheric Chemistry introduces basic concepts about the characterization, formation, and impacts of ambient aerosol particles as an introduction to graduate students new to the field. Each chapter also provides an up-to-date synopsis of the latest knowledge of aerosol particles in atmospheric chemistry.

Author: V. Faye McNeill
Publisher: Springer
ISBN: 3642412157
Category : Science
Languages : en
Pages : 267

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Christian George, Barbara D’Anna, Hartmut Herrmann, Christian Weller, Veronica Vaida, D. J. Donaldson, Thorsten Bartels-Rausch, Markus Ammann - Emerging Areas in Atmospheric Photochemistry. Lisa Whalley, Daniel Stone, Dwayne Heard - New Insights into the Tropospheric Oxidation of Isoprene: Combining Field Measurements, Laboratory Studies, Chemical Modelling and Quantum Theory. Neil M. Donahue, Allen L. Robinson, Erica R. Trump, Ilona Riipinen, Jesse H. Kroll - Volatility and Aging of Atmospheric Organic Aerosol. P. A. Ariya, G. Kos, R. Mortazavi, E. D. Hudson, V. Kanthasamy, N. Eltouny, J. Sun, C. Wilde - Bio-Organic Materials in the Atmosphere and Snow: Measurement and Characterization. V. Faye McNeill, Neha Sareen, Allison N. Schwier - Surface-Active Organics in Atmospheric Aerosols.

Author: Theresa M. Kucinski
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Aerosols are suspended liquid or solid particles that are ubiquitous in the atmosphere. These particles can affect the climate directly by absorbing/scattering radiation or indirectly by helping the formation of clouds. Aerosol particles have an overall net cooling effect, however, there is a large uncertainty associated with the magnitude of cooling. A portion of this uncertainty is due to an incomplete understanding of the chemical and physical properties of particles. Aerosol particles also exist over a large range of sizes which can alter these properties due to size effects, that would require parameterization. Properties that need to be further explored include morphology, phase transitions, and their respective size dependence. This dissertation explores size effects associated with liquid-liquid phase separation (LLPS) and the development of a new method to study phase transitions in submicron particles. Previously, we found that LLPS is a size-dependent process in submicron particles consisting of an organic compound and a single salt component. The size-dependence produces large particles that phase separate while small particles remain homogeneous. Particles in the atmosphere are complex and can contain hundreds of organic compounds. To expand the size-dependence study to better mimic ambient aerosol, we studied particles consisting of complex organic mixtures and ammonium sulfate. The organic mixtures included: dicarboxylic acids (DCA), complex organic mixtures (COM), and [alpha]-pinene secondary organic matter (SOM). We imaged the particles with cryogenic- transmission electron microscopy (cryo-TEM) and all systems displayed size-dependent morphology. Additionally, we observed the presence of three-phase particles in addition to 'channel' morphology. Our results provide further evidence that size-dependent LLPS may be relevant for ambient aerosol. Studying phase transitions in individual submicron particles proves to be difficult with currently available techniques. We present a new method that flash freezes particles to create snapshots into the phase transition process for submicron particles. This method uses vitrification, which is a technique which cools the sample rapidly such that crystallization is avoided and the humidified properties are retained. A temperature controlled flow tube is use to vitrify the particles at several relative humidity (RH) points followed by imaging with cryo-TEM. The method was verified using efflorescence of potassium salts. Additionally, we demonstrate the ability to image the process of LLPS in submicron particles consisting of 2-methylglutaric acid (2-MGA) and ammonium sulfate. We applied the flash freeze technique to study the dynamics of LLPS in submicron particles. In particular, we studied separation relative humidity (SRH), which is defined as the RH that separation occurs, for 2-MGA/ammonium sulfate, 1,2,6-hexantriol/ammonium sulfate, and COM/ammonium sulfate. Particles were vitrified and imaged above phase separation, throughout the process of separation, and until LLPS reaches final maturation. We found that the onset of separation is lower for submicron particles than for particles several micrometers in diameter, indicating a potential shift in the phase diagrams. Additionally, the average SRH is significantly lower for submicron particles in the nucleation and growth regime compared to bulk systems. The decrease in SRH indicates a need for new parameterizations to accurately define particles in models. We also found that the dynamics of separation is a random process that is not dependent on size except for the smallest particles which remain homogeneous throughout. The onset of separation occurs over a large range of RH and our results suggest that this is a result of the energy barrier associated with nucleating a new phase.

Author: Peter Warneck
Publisher: Springer Science & Business Media
ISBN: 3642614450
Category : Science
Languages : en
Pages : 270

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The "European Experiment on the Transport and Transformation of Environmentally Relevant Trace Constituents over Europe" (EUROTRAC) was established in 1986 to tackle the scientific problem and combine the expertise, knowledge and resources in Europe, in order to apply them over a large region covering the greater part of the continent. EUROTRAC is a coordinated multidisciplinary scientific research project involving field measurements, laboratory studies, instrument development and development of comprehensive computer models for the simulation of the physical and chemical processes in the lower atmosphere.

Author:
Publisher: ScholarlyEditions
ISBN: 1481674331
Category : Science
Languages : en
Pages : 346

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Chlorides—Advances in Research and Application: 2013 Edition is a ScholarlyEditions™ book that delivers timely, authoritative, and comprehensive information about Cadmium Chloride. The editors have built Chlorides—Advances in Research and Application: 2013 Edition on the vast information databases of ScholarlyNews.™ You can expect the information about Cadmium Chloride in this book to be deeper than what you can access anywhere else, as well as consistently reliable, authoritative, informed, and relevant. The content of Chlorides—Advances in Research and Application: 2013 Edition has been produced by the world’s leading scientists, engineers, analysts, research institutions, and companies. All of the content is from peer-reviewed sources, and all of it is written, assembled, and edited by the editors at ScholarlyEditions™ and available exclusively from us. You now have a source you can cite with authority, confidence, and credibility. More information is available at http://www.ScholarlyEditions.com/.

Author: Yuan You
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 5

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Ambient aerosols are frequently composed of hygroscopic inorganic salts such as chlorides, sulfates and nitrates in either pure or mixed forms. Such inorganic salt aerosols exhibit the properties of deliquescence and efflorescence in air. The phase transformation from a solid particle to a saline droplet usually occurs spontaneously when atmospheric relative humidity reaches a level specific to the chemical composition of the aerosol particle. Conversely, when relative humidity decreases and becomes low enough, a saline droplet will evaporate and suddenly crystallize, expelling all its water content. Information on the composition and temperature dependence of these properties is required in mathematical models for describing the dynamic and transport behavior of ambient aerosols. Experiments are carried out in the temperature range 5--35°C, using single particles individually suspended in an electrodynamic cell that can be evacuated and back filled with water vapor. The phase transformation of the aerosol particle is monitored by laser light scattering and the relative humidity at the transition point is determined by directly measuring the water vapor pressure in the cell. Results are obtained for particles containing either a single salt or a preselected mixture of NaCl, KCl, NaNO3, Na2SO4 and (NH4)2SO4, which are common constituents of ambient aerosols. A theoretical model on the composition and temperature dependence of the deliquescence properties is developed for single and two-salt aerosol systems.