Koldioxidutsläpp (CO2) från energiproduktionsindustrin och transportsektorn globalt påverkar miljön negativt. Länder har enats om att minska utsläppen för att nå målet om en genomsnittlig temperaturökning på 1,5 °C till 2030. Trots detta förväntas de globala utsläppen av CO2 från fossila bränslen och industriella processer vara cirka 40 Gton per år fram till 2100. För att dra nytta av CO2-utsläppen och skapa värdefulla produkter med negativa utsläpp är mineralkarbonatisering en önskvärd process. Denna process innebär att CO2 och mineraler löses upp i en alkalisk lösning och bildar stabila produkter. Faktorer som partikelstorlek hos mineralerna och CO2-lösningshastigheten påverkar mineralkarbonatiseringens hastighet. Experiment utfördes med en batchreaktor från Paebbl AB och en matematisk modell utvecklades i Matlab. Resultaten jämfördes för olika partikelstorlekar i tre motståndsfall. Större partikelstorlek hos olivin visade sig öka tiden för total konvertering, oavsett motståndstyp. De modellerade motstånden beskrev inte tillräckligt processen och indikerade att alla tre motstånd har en samtidig och enhetlig effekt på olivinmineralisering, utöver eventuella begränsningar som föroreningar och biprodukter. Mineraliseringsexperiment med 20 μm partiklar under en timme gav 34,4% omvandling, medan 10 μm partiklar under två timmar gav 46,7% omvandling. En inledande undersökning av massöverföringsbegränsningar visade att CO2-lösningshastigheten inte är den begränsande faktorn, utan lägre omrörningshastigheter och beteendet hos (CO2 + olivin)-systemet behöver ytterligare studeras. Framtida forskning bör fokusera på att lösa dessa begränsningar. / Carbon dioxide (CO2) emissions from the energy production industry and the transportation sector globally negatively affect the environment. A prominent example is the interconnection of carbon with the greenhouse effect. Countries have agreed to mitigate their emissions and try to fulfill the target of 1.5 oC average temperature increase by 2030, but in order to do so the global emissions of CO2 from fossil fuels and industrial processes will still lead up to the astonishing amount of 40 Gtons of CO2 each year until 2100.  It is apparent that processes that try to take advantage of the emitted CO2 creating valuable products with negative emissions are highly desired. One of these is mineral carbonation, where CO2 and minerals dissolve in an alkaline solution and form stable products. Many factors affect the rate at which mineral carbonation happens. The effect of the particle size of the mineral in the process will be investigated, along the CO2 dissolution rate through the overall gas-liquid mass transfer coefficient (kLa), in order to get a better understanding of the process. Experiments were conducted with a batch reactor provided by Paebbl AB and a mathematical model was developed in Matlab. The experimental and numerical results, in regards to the particle size, were then compared for the cases of three resistances. This model can be developed further for use in a continuous mineralization process. The results revealed that increasing the particle size of olivine leads to a significant increase in the time required for total conversion, irrespective of the resistance type. The modelled resistances were found to inadequately describe the process, suggesting a simultaneous and uniform effect of all three resistances on olivine mineralization, in addition to the effect of other possible limitations such as impurities and by-products. Mineralization experiments with 20μm particles and a duration of 1 hour led to 34.4% conversion, whereas experiments with 10μm particles and a duration of 2 hours resulted in 46.7% conversion. Finally, the initial investigation of the mass transfer limitations in a system of CO2 and water led to an average kLa coefficient of 191 h-1, suggesting that the CO2 dissolution rate is not the limiting factor. However, the impact of lower stirring rates remains unexplored due to the absence of appropriate instrumentation and the behaviour of the (CO2 + olivine) system should also be studied. Future research should aim to address these limitations.

Title: Formation and transformation of atmospheric aerosol in boundary layer Author: Mgr. Adéla Holubová Šmejkalová Institute: Institute for Environmental Studies Supervisor: Ing. Vladimír Ždímal, Dr., Institute of Chemical Process Fundamen- tals of the CAS Training workplace: Institute of Chemical Process Fundamentals of the CAS Abstract: The experimental measurement of aerosol clusters from 1.17 nm in size was carried out from August 2016 till December 2018 at the National Atmospheric Observatory Košetice. Atmospheric conditions leading to aerosol clusters stabili- zation, fresh particles formation and particle growth were analyzed. Data of days with no new particle formation confrmed the connection between mixing layer height development and decrease of total aerosol number concentration together with lower gaseous pollutant concentrations. On the contrary, new particle for- mation process overcomes dilution of the atmosphere by increasing the number of freshly nucleated particles. Only decreasing gaseous pollutant concentrations were observed during these events. The atmospheric boundary layer was high du- ring new particle formation events that can mean enrichment of the atmosphere by other components transported by long-range transport or some transfer from the free troposphere. The measurement in...

Addition of nano particles to cooling fluids has shown marked improvement in the heat transfer capabilities. Nanofluids, liquids that contain dispersed nanoparticles, are an emerging class of fluids that have great potential in many applications. There is a need to understand the fundamental behavior of nano dispersed particles with respect to their agglomeration characteristics and how it relates to the heat transfer capability. Such an understanding is important for the development and commercialization of nanofluids. In this work, the stability of nano particles was studied by measuring the zeta potential of colloidal particles, particle concentration and size. Two different sizes of silica nano particles, 10 nm and 20 nm are used in this investigation at 0.2 vol. % and 0.5 vol. % concentrations. The measurements were made in deionized (DI) water, buffer solutions at various pH, DI water plus HCl acid solution (acidic pH) and DI water plus NaOH solution (basic pH). The stability or instability of silica dispersions in these solutions was related to the zeta potential of colloidal particles and confirmed by particle sizing measurements and independently by TEM observations. Low zeta potentials resulted in agglomeration as expected and the measured particle size was greater. The heat transfer characteristics of stable or unstable silica dispersions using the above solutions were experimentally determined by measuring heat flux as a function of temperature differential between a nichrome wire and the surrounding fluid. These experiments allowed the determination of the critical heat flux (CHF), which was then related to the dispersion characteristics of the nanosilica in various fluids described above. The thickness of the diffuse layer on nano particles was computed and experimentally confirmed in selected conditions for which there was no agglomeration. As the thickness of the diffuse layer decreased due to the increase in salt content or the ionic content, the electrostatic force of repulsion cease to exist and Van der Waal's force of agglomeration prevailed causing the particles to agglomerate affecting the CHF. The 10nm size silica particle dispersions showed better heat transfer characteristics compared to 20nm dispersion. It was also observed that at low zeta potential values, where agglomeration prevailed in the dispersion, the silica nano particles had a tendency to deposit on the nickel chromium wire used in CHF experiments. The thickness of the deposition was measured and the results show that with a very high deposition, CHF is enhanced due to the porosity on the wire. The 10nm size silica particles show higher CHF compared to 20nm silica particles. In addition, for both 10nm and 20nm silica particles, 0.5 vol. % concentration yielded higher heat transfer compared to 0.2 vol. % concentration. It is believed that although CHF is significantly increased with nano silica containing fluids compared to pure fluids, formation of particle clusters in unstable slurries will lead to detrimental long time performance, compared to that with stable silica dispersions.

Return liquor from thermal hydrolysis process (THP) can significantly add to the nitrogen load of a wastewater treatment plant (WWTP) and introduce UV quenching substances to the wastewater stream when recycled. While there are mature technologies in place to handle the inorganic nitrogen produced due to the thermal pretreatment, organic nitrogen remains a parameter of concern for utilities employing THP pretreatment. The impact of operating conditions of the THP on dissolved organic nitrogen (DON) and UV absorbance in return liquor was investigated. Operating conditions studied were (1) operating temperature (2) solids retention time (SRT) in the anaerobic digester (3) THP flash pressure (4) the effect of co-digestion of sewage sludge with food waste and, (5) polymer conditioning. Operating temperature and polymer dose had the most significant impact on DON and UV quenching. It was found that an increase in operating temperature resulted in an increase in DON, which was primarily contributed by the hydrophilic fraction. An increase in temperature also resulted in increased UV254 absorbance. However, this trend was not linear and the increase was more pronounced when the temperature was increased from 150 C to 170 C. Increasing flash pressure from 25 psi to 45 psi did not have a significant impact on the return liquor. However, increasing the flash pressure to 75 psi increased the DON and UV254 absorbing compounds. Co-digesting the sludge with food waste resulted in a slight increase in DON and a decrease in dissolved organic carbon (DOC) and UV quenching compounds. Increasing the SRT from 10 days to 15 days resulted in a slight decrease in DON but did not have any impact on UV254 absorbance. Overall, it can be concluded that optimizing operating conditions of thermal hydrolysis process can result in decreased DON and UV quenching compounds in the recycle stream. / Master of Science

The process of milling drugs to obtain samples with a desirable particle size range has been widely used in the pharmaceutical industry, especially for the production of drugs for inhalation. However by subjecting materials to milling techniques surfaces may become thermodynamically activated which may in turn lead to formation of amorphous material. Polymorphic conversions have also been noted after milling of certain materials. Salt and cocrystal formation is a good way of enhancing the properties of an API but little or no work has been published which investigates the stability of these entities when subjected to milling. Different milling techniques (ball and jet) and temperatures (ambient and cryogenic) were used to investigate the milling behaviour of polymorphs, salts and cocrystals. All materials were analysed by XRPD and DSC to investigate any physical changes, i.e. changes in melting point and by inverse gas chromatography (IGC) to investigate whether any changes in the surface energetics occurred as a result of milling. Another aim of this thesis was to see if it was possible to predict the milling behaviour of polymorphs by calculating the attachment energies of the different crystal facets using Materials Studio 4.0. These results were compared to the IGC data to see if the predicted surface changes had occurred. The data collected in this study showed that different milling techniques can have a different effect on the same material. For example ball milling at ambient temperature and jet micronisation of the SFZ tosylate salt caused a notable increase in the melting point of the material whereas ball milling at cryogenic temperatures did not cause this to happen. The IGC data collected for this form also showed a contrast between cryomilling and the other two techniques. The study also showed that the formation of salts and cocrystals does not necessarily offer any increased stability in terms of physical properties or surface energetics. Changes in melting point were observed for the SFZ tosylate salt and the IMC:Benzamide cocrystal. Changes in the specific surface energies were also observed indicating that the nature of the surfaces was also changing. The materials which appeared to be affected the least were the two stable polymorphs, gamma IMC and SFZ III. The computational approach used has many limitations. The software does not allow for conversion to the amorphous form or polymorphic conversions. Such conversions were seen to occur, particularly for the metastable polymorphs used, meaning that this computational approach may only be suitable for stable polymorphs.

Fuktbevarare är de produkter som oftast skrivs och rekommenderas av dermatologer, och den vanligaste typen av fuktgivare är lotioner och krämer. Dessa produkter är emulsioner, vilka ofta innehåller medicinsk vit olja (MWO) på grund av deras skyddande egenskaper samt enastående hudkompabilitet. Traditionellt så har de MWO som används varit parafinska. Då naftenoljor ofta har visat sig ha bättre emulsions stabilitet, har detta examensarbete ämnat attjämföra emulsions stabiliteten för Nynas ABs nya MWO, N-MWO, med en parafinsk motsvarighet, P-MWO. Jämförelsen av de två oljorna genomfördes genom att variera följande faktorer: olje- och emulgator typ, koncentration av emulgator samt både med och utan parfym. De två emulgator system som användes bestod av Promulgen D (en kommersiell produkt från Lubrizol) samt kombinationen av Tween 80 och Span 20. Bättre emulsionsstabilitet och mindre droppstorlek och fördelning utficks då högre koncentration Promulgen D användes. En högre koncentration av Tween 80 och Span 20 gav dock inte samma gynnsamma effekt. Resultaten från samtliga tester påvisade att emulsions stabiliteten inte påverkades utav parfym. Det som istället gav störst påverkan var typ av emulgator. De prover som innehöll P-MWO samt Tween 80 och Span 20 fasseparerade. Detta berodde dock troligen mer på att P-MWO inte var kompatibel med dessa emulgatorer eftersom oljetypen inte påverkade emulsionsstabiliteten när Promulgen D användes som emulgator. / Moisturizers are the most prescribed products in dermatology, and the most common type of moisturizer delivery systems are lotions and creams. These are emulsions and often contain medical white oil (MWO) due to their protective properties and excellent skin compatibility. The MWO used in cosmetics have traditionally been paraffinic. However, as naphthenic oils often have been proven to create better emulsion stability, this thesis aimed to compare Nynas AB's new MWO, N-MWO, with a paraffinic oil, P-MWO, with similar properties regarding their emulsion stability. The two oils were compared by analyzing their emulsion stability using a rheometer and a Mastersizer 3000 while varying the following factors: type of oil, type of emulsifier, emulsifier concentration, and with and without perfume. The two emulsifying systems used were the commercial product Promulgen D from Lubrizol and the combination of Tween 80 and Span 20. Better emulsion stability and smaller droplet size distribution were obtained when a higher content of Promulgen D was added. However, a higher concentration of Tween 80 and Span 20 did not have the same favorable effect. The results showed that the addition of perfume had no effect, while the type of emulsifier influenced the emulsion stability the most. The samples made from Supela 240 and Tween 80 and Span 20 phase separated. This was more likely due to P-MWOs incompatibility with these emulsifiers as oil type did not influence the emulsion stability when Promulgen D was used as an emulsifier.

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Twin screw wet granulation has been proved as a feasible alternative for traditional batch granulation process due to its continuous processing feature; considered as a significant processing method especially in the pharmaceutical industry. This thesis will explore the processibility of twin screw wet granulation with various formulations. The first section of the thesis focused on examining the processibility of wet granulation in a twin screw while using various grades of hydroxypropyl methylcellulose (HPMC) as an extended-release excipient. The method to find the processibility was by modifying the liquid-to-solid ratio for each formulation. The process window was defined by examining the amount of granules that fall in a pre-determined acceptable size range. This part focused on three substitution types of HPMC (Type 2910, Type 2208, and Type 2906) that varied in molecular weights. It was found that only Type 2910 HPMC showed a shift in the process window (also known as granulation range) in relation to the molecular weight of the formulations. A higher demand for binder liquid was found for higher molecular weight Type 2910 HPMC in order to form granules with acceptable sizes. The second part of this thesis was focused on understanding the process variables that might influence the processibility of the HPMC formulations. This part examined the impact of feed rate on the granulation range of Type 2910 HPMC specifically was examined. Multiple feed rates were tested, and it was found that the granulation range for lower molecular weight Type 2910 HPMC was easier to shrink when higher feed rates were applied. A transition in the granule formation method from liquid-bridging to compaction with respect to the feed rate was found for low molecular weight HPMC, whereas the high molecular weight HPMC always formed granules through compaction at all feed rates due to strong water retainability. / Thesis / Master of Applied Science (MASc)

Concrete is the most widely used man-made material in the world. Its versatility, strength, and relative ease of construction allow it to be used in the majority of civil infrastructure. However, concrete production plays a significant role in greenhouse gas emissions, accounting for around 8% of CO2 emissions worldwide. This thesis aims to reduce the demand for cement in concrete construction, thus reducing the carbon footprint of the concrete, by focusing on classifying and determining the effectiveness of seven different quarry by-products as partial replacements of cement. Several methods were utilized in this study to characterize the quarry by-products: particle size distribution, helium pycnometry, X-Ray diffraction, X-Ray fluorescence, scanning electron microscopy, and a modified ASTM C1897 Method A that utilizes isothermal calorimetry and thermogravimetric analysis. These various methods allowed for the determination of the physical properties (e.g., gradation, specific gravity, and morphology) and the chemical properties (e.g., mineralogy and reactivity in a cementitious system). The quarry by-products were classified as four granites, two limestones, and one greenstone. These quarry by-products were found to be non-pozzolanic and non-hydraulic. However, there are indications that there may be reactions with the various clays and feldspars in the quarry by-products with calcium hydroxide, which suggests a degree of reactivity that is not necessarily pozzolanic or hydraulic. / Master of Science / Concrete is the most widely used man-made material in the world. Its versatility, strength, and relative ease of construction allow it to be used in the majority of civil infrastructure. However, concrete production plays a significant role in greenhouse gas emissions, accounting for around 8% of CO2 emissions worldwide. This thesis aims to reduce the demand for cement in concrete construction, thus reducing the carbon footprint of the concrete, by focusing on classifying and determining the effectiveness of seven different quarry by-products as partial replacements of cement. Several methods were utilized in this study to determine the physical properties (e.g., gradation, specific gravity, and morphology) and the chemical properties (e.g., mineralogy and reactivity in a cementitious solution) of the materials. The quarry by-products were classified as four granites, two limestones, and one greenstone. In general, these quarry by-products were not found to be reactive as a supplementary cementitious material, although the data may suggest some degree of reactivity between calcium hydroxide and the clays and/or feldspars in the quarry by-products.

Ultrasound directed self-assembly (DSA) utilizes the acoustic radiation force associated with a standing ultrasound wave field to organize particles dispersed in a fluid medium into specific patterns. The ability to tailor the organization and packing density of spherical particles using ultrasound DSA in a viscous fluid medium is crucial in the context of (additive) manufacturing of engineered materials with tailored properties. However, the fundamental physics of the ultrasound DSA process in a viscous fluid medium, and the relationship between the ultrasound DSA process parameters and the specific patterns of particles that result from it, are not well-understood. Researchers have theoretically described the acoustic radiation force and the acoustic interaction force that act on spherical particles in a standing ultrasound wave field in both inviscid and viscous media. In addition, they have solved the forward and inverse ultrasound DSA problem in an inviscid medium, in which they relate the patterns of particles and the ultrasound DSA operating parameters. However, no theoretical model exists that allows simulating the steady-state and transient local particle packing density in a viscous medium during ultrasound DSA. Thus, in this dissertation, we (i) theoretically derive and experimentally validate a model to determine the steady-state locations where spherical particles assemble during ultrasound DSA as a function of medium viscosity and particle volume fraction. (ii) We also theoretically derive and experimentally validate a model to quantify the steady-state and transient local packing density of spherical particles within the pattern features that result from ultrasound DSA. Using these models, we quantify and predict the locations where spherical particles assemble during ultrasound DSA in a viscous medium, considering the effects of medium viscosity and particle volume fraction. We demonstrate that the deviation between locations where particles assemble in viscous and inviscid media first increases and then decreases with increasing particle volume fraction and medium viscosity, which we explain by means of the sound propagation velocity of the mixture. In addition, we quantify and predict the steady-state and transient local packing density of spherical particles within the pattern features, using ultrasound DSA in combination with vat photopolymerization (VP). We show that the steady-state local particle packing density increases with increasing particle volume fraction and increases with decreasing particle size. We also show that the transient local particle packing density increases with increasing particle volume fraction, decreasing particle size, and decreasing fluid medium viscosity. Increasing particle size and decreasing fluid medium viscosity decreases the time to reach steady-state. Finally, we implement single and multiple scattering in the calculation of the acoustic radiation force for spherical particles in a viscous medium and quantify their relative contributions to the calculation of the acoustic radiation force as a function of ultrasound DSA operating parameters and material properties. We demonstrate that the deviation between considering single and multiple scattering may reach up to 100%, depending on the ultrasound DSA process parameters and material properties. Also, increasing the particle volume fraction increases the need to account for multiple scattering. Quantifying and predicting the local packing density of spherical particles during ultrasound DSA in a viscous medium, as a function of ultrasound DSA process parameters is crucial towards using ultrasound DSA in engineering applications, in particular (additive) manufacturing of engineered polymer matrix composite materials with tailored properties whose properties depend on the spatial organization and packing density of particles in the matrix material. / Doctor of Philosophy / Ultrasound directed self-assembly (DSA) is a technique that uses ultrasound waves to arrange small particles submerged in a fluid into specific patterns. When combined with other manufacturing techniques, ultrasound DSA can be used to fabricate composite materials that derive their properties from the spatial organization of particles in a matrix material. However, ultrasound DSA in viscous fluids is not well-understood. Researchers have studied the forces associated with ultrasound waves that move small spherical particles in an inviscid fluid medium (fluids that experience little to no internal resistance to flow), and they have demonstrated intricate control of the patterns of particles that form using ultrasound DSA. However, that knowledge is not currently available for ultrasound DSA in viscous media. In this dissertation, we develop and evaluate theoretical models to understand ultrasound DSA of small spherical particles in a viscous fluid medium. We simulate where particles organize and how densely they pack together. We also determine the difference of the time-dependent motion of particles in a viscous fluid compared to that in an inviscid fluid medium and relate the difference to the number of particles submerged in the fluid and the viscosity of the fluid. Additionally, we examine the effect of particle size and fluid viscosity on the speed by which the particles reach their final location. We also study how ultrasound waves interact with multiple small particles in a viscous fluid, focusing on the forces that move these particles. We explore two models that account for single and multiple ultrasound wave scattering. Scattering is the process by which ultrasound waves deflect in different directions when they encounter a particle. The results show that the difference between single and multiple scattering models can be significant, depending on the ultrasound DSA process parameters and the properties of the fluid and particles. In general, the importance of accounting for multiple scattering increases with the number of particles submerged in the fluid. Understanding particle packing density when using ultrasound DSA in a viscous fluid is essential in many engineering applications, in particular manufacturing of composite materials that derive their properties from the spatial arrangement of particles in a matrix material.