To see the other types of publications on this topic, follow the link: Continuous flow.
Dissertations / Theses on the topic 'Continuous flow'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Continuous flow.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Faizullah, Azad Tawfiq. "Continuous flow injection analysis." Thesis, University of Hull, 1985. http://hydra.hull.ac.uk/resources/hull:16437.
Full text
2
Pal, S. "Understanding flow of solid in continuous flow reactors." Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2019. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/5989.
Full text
3
McPake, Christopher C. "New continuous flow oxidation methodology." Thesis, Durham University, 2011. http://etheses.dur.ac.uk/3244/.
Full textAbstract:
The HOF.MeCN complex, formed from the reaction of elementary fluorine with aqueous acetonitrile, was discovered by Shlomo Rozen in 1987 and, in a series of publications, he demonstrated that the complex is a uniquely effective electrophilic oxygen transfer agent. However, it is estimated that the HOF.MeCN complex has a half life of a few hours at 0ºC and thus, must be produced and used immediately when required. In addition to this, highly exothermic, rapid oxidation processes can be problematic with reaction control and safety when reagents are added into an excess of a highly oxidizing medium. Consequently, scale-up of oxidations to a larger industrial level using the HOF.MeCN complex in batch processes would not be possible. In recent years, continuous flow reactors using microchannels have been viewed as a viable method for avoiding many of the problems encountered when a laboratory process is scaled-up. The low chemical inventory of such reactors means that even highly reactive reactions can be performed safely and, with the application of multiple reaction channels in parallel, large quantities of product can be easily obtained. In this thesis we present new continuous flow methodology for the in situ generation of HOF.MeCN and, without isolation, immediate substrate oxidation in a two-step process. The continuous process, therefore, provides a genuine method for oxidizing large quantities of material, without the problems associated with batch oxidations. Scale-up oxidations of various amines, alkenes, and anilines are also presented along with a safe and accurate method for calibrating HOF.MeCN amounts.
4
Dahnoun, Naim. "Continuous monitoring of blood flow." Thesis, University of Leicester, 1990. http://hdl.handle.net/2381/34319.
Full textAbstract:
An extensive review of the literature revealed that there are still significant weakness in the available technology for blood flow measurement. This dissertation describes two techniques for blood velocity measurement. The first is an invasive method which uses multimodal optical fibres for light transmission to and from a sensing tip, which attenuates the light depending upon the blood velocity. The design and construction of this flowmeter is presented and bench results shown. The modulated light is transmitted to the detection and processing circuit and provision is made for the transducer to be insensitive to pressure fluctuations and ambient light. The second technique, which is noninvasive, uses a continuous wave Doppler ultrasonic technique; the instrument designed is a portable directional Doppler velocimeter with purpose-built probes intended for monitoring blood flow in femorodistal bypass grafts in ambulatory patients. This portable unit differs from conventional Doppler units in many respect which are described. This unit has been developed in order to understand the behaviour of blood flow in grafts while the patients are persuing everyday tasks. A postoperative study of successful in situ vein grafts from 8 patients has been undertaken to determine the feasibility of the technique. This pilot study shows that posture can have an effect on blood flow in grafts, and also shows that it is possible to monitor blood velocity with Doppler techniques for a long period of time, without intervention of an operator.
5
Lovick, Jonathon. "Horizontal, oil-water flows in the dual continuous flow regime." Thesis, University College London (University of London), 2004. http://discovery.ucl.ac.uk/1383486/.
Full textAbstract:
The research presented in this thesis is concerned with the flow behaviour of two-phase, liquid-liquid, oil-water flow through horizontal pipes. The test liquids used were oil (density 828kg/rn3, viscosity 6x iO 3 Pa s) and water, with experiments carried out in a purpose built test facility with a stainless steel pipe (internal dia. 38mm, length 8m). Visual observation of the flow was possible at low mixture velocities through a lm transparent pipe at the end of the test section. At higher mixture velocities local probes were used for flow pattern identification. These local probes were a conductivity probe for identifying the continuous phase, and a high frequency impedance probe for measuring local phase distribution. A dual sensor impedance probe was also developed for measuring local drop velocity and also the drop chord length distributions. Pressure gradient was also measured using a differential pressure transducer, and in-situ phase fractions were obtained using Quick Closing Valves. Experimental results show that the dual continuous flow regime, where both phases retain their continuity while there is mixing at the interface, dominates at all input oil fractions at low mixture velocities and intermediate oil fractions at high mixture velocities. In general the pressure drop of the two-phase mixture is lower than that of single phase oil. At higher mixture velocities a minimum in pressure gradient appeared at high oil fractions perhaps as a combination of the drag reduction phenomenon and the relative fraction of the oil and water layers in the pipe. At the highest mixture velocity this minimum was at the boundary of fully dispersed oil continuous flow with dual continuous flow. Velocity ratios are shown to increase with increasing oil fraction at low mixture velocities, with this trend reversing at high mixture velocities. These trends in the pressure gradient and velocity ratio can be explained using the phase distribution diagrams, with the interfacial curvature greatly affecting velocity ratio. Local chord length data shows that, in general, drop sizes decrease with increasing distance from the interface and that oil drops tend to be slightly larger than water drops. Mixture velocity did not significantly affect the drop size of either phase in dual continuous flow. A modified version of the two-fluid model was suggested for dual continuous flow that treats the upper and lower layers as dispersions and uses experimental entrainment to calculate their properties. Better predictions were obtained when friction factors that accounted for the drag reduction phenomenon were used to calculate wall shear stresses.
6
Bessoth, Fiona Gabriele. "Microstructure for efficient continuous flow mixing." Thesis, Imperial College London, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367869.
Full text
7
Scovell, Katherine A. "Continuous flow reactions at high pressure." Thesis, University of Nottingham, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.537684.
Full text
8
Mueller, Simon T. R. "Diazo compounds in continuous flow technology." Thesis, Cardiff University, 2015. http://orca.cf.ac.uk/86662/.
Full textAbstract:
Diazo compounds are highly reactive carbene precursors which can be used to generate molecular complexity rapidly. However, diazo compounds are highly energetic and dangerous compounds and therefore, their use in large-scale applications remains rare. In this work, the use of continuous flow technology for the safe, efficient and scalable use of diazo compounds is described. By using flow chemistry, diazo compounds were safely generated within small diameter devices and directly used in subsequent reactions without a hazardous isolation of the diazo reagents. This thesis describes five new protocols for the use of diazo compounds. In the first project, ethyl diazoacetate (EDA) was generated safely in flow and used in subsequent aldol addition reactions to aldehydes with high yields (right). The preparation of the organometallic ethyl lithiodiazoacetate species in flow was achieved in the second project and used for the addition to ketones (left). Detailed kinetic and thermal studies on aryl diazoacetates were performed in the third project which yielded a new, multistep continuous flow protocol for the use of donor / acceptor carbenes. Rapid reaction optimisation was achieved using in-line infrared spectroscopy. Purification of the diazo species was performed in flow using in-line liquid / liquid extraction methodology. The fourth protocol entails the rapid assembly of complex lactone-cyclopropane structures of biological interest from diazo compounds in a combination of flow and batch technologies (left). In the final project, the stereoselective preparation of indolines using diazo compounds is discussed (right).
9
Sharma, Y. "Continuous flow synthesis of organic compounds." Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2017. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/4520.
Full text
10
Kelly, Liam P. (Liam Porter). "Development of a continuous-flow synthesis of neostigmine methylsulfate and studies toward a continuous-flow synthesis of lisinopril." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/122853.
Full textAbstract:
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Chemistry, 2019Cataloged from PDF version of thesis.
Includes bibliographical references.
[color illustration] Herein, we describe the development of a continuous flow synthesis of neostigmine methyl sulfate, an acetylcholinesterase inhibitor on the WHO list of essential medicines, and the transfer of the synthesis into a next-generation reconfigurable frame developed by our collaborators. Starting from 3-dimethylaminophenol, the synthesis provides a throughput of approximately 46.8 g/day (or 93,600 doses/day) of crude neostigmine methyl sulfate. The synthesis also showcases a prototype in-line evaporation unit that operates without any added carrier gas. Dr. Christina Dai performed early screening of lithium bases. Dr. Yuqing Cui and Dr. Naomi Briggs developed the downstream purification sequence. Dr. Nopphon Weeranoppanant developed the in-line evaporator and, along with Dr. Dale Thomas, assisted with performing the synthesis within their developed frame. Liam P. Kelly developed the continuous synthesis of neostigmine methyl sulfate. [color illustration] Lisinopril is a member of a large family of ACE inhibitors generally known as N-carboxyethyl dipeptides. Of this family, lisinopril is the most commonly prescribed. All known routes to lisinopril require isolation of several synthetic intermediates and protecting group manipulations, thus, development of an efficient continuous synthesis would provide great benefit. Herein we describe our investigation of several routes to generate intermediates of lisinopril with the end goal of a fully continuous synthesis, high material throughput, and minimal protecting group manipulations. Liam P. Kelly performed all work described within this chapter.
by Liam P. Kelly.
Ph. D.
Ph.D. Massachusetts Institute of Technology, Department of Chemistry
11
Peterson, Olga Yuris. "Transferring pharmaceutical batch technology to continuous flow." Thesis, Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/39510.
Full textAbstract:
The current trend in the pharmaceutical industry is towards continuous flow processes. Continuous flow reactor technology can produce a cheaper, better quality product at reduced energy and environmental cost through more efficient mass and heat transfer. It also enables a simplified and faster approach to bulk production by scaling out as opposed to scaling up. The research presented here focuses on the configuration and installation of a continuous flow system into the laboratory, and the transfer of a Meerwein-Ponndorf-Verley (MPV) reduction from batch to continuous mode.
The Corning® glass continuous flow reactor in our laboratory utilizes specially-designed mixing structures for enhanced mass transfer. Additionally, the glass reactor offers nonreactivity and corrosion resistance over a wide range of temperature and pressure, which conventional steel reactors do not allow. The MPV reduction is a well-known method to prepare primary and secondary alcohols from aldehydes and ketones, respectively. The traditional MPV reduction protocol (Al(OiPr)₃ in isopropanol) was modified to enable the technological transfer from batch to continuous mode. This is the first time MPV reduction reactions were carried out in continuous mode. As a result, the MPV reduction of the model compound, benzaldehyde, was successfully conducted with 60% less catalyst and product yield was improved up to 20% (average of 10%) in continuous flow reactions as compared to current batch technology. These results are being used to develop a technology roadmap for the pharmaceutical industry to implement continuous flow processes in their manufacturing operations.
12
Rossi, D. "Adipic acid sonocrystallization in continuous flow microchannels." Thesis, University College London (University of London), 2017. http://discovery.ucl.ac.uk/1557884/.
Full textAbstract:
Crystallization is widely employed in the manufacture of pharmaceuticals during the intermediate and final stages of purification and separation. The process defines drug chemical purity and physical properties: crystal morphology, size distribution, habit and degree of perfection. Particulate pharmaceuticals are typically manufactured in conventional batch stirred tank crystallizers that are still inadequate with regard to process controllability and reproducibility of the final crystalline product. Variations in crystal characteristics are responsible for a wide range of pharmaceutical formulation problems, related for instance to bioavailability and the chemical and physical stability of drugs in their final dosage forms. This thesis explores the design of a novel crystallization approach which combines in an integrated unit continuous flow, microreactor technology, and ultrasound engineering. By exploiting the various benefits deriving from each technology, the thesis focuses on the experimental characterization of two different nucleation systems: a droplet-based system and a single-phase system. In the former, channel fouling is avoided using a carrier fluid to segment the crystallizing solution in droplets, thus avoiding the contact with the walls. In the latter channel blockage is prevented using larger channel geometries and employing higher flow rates. The flexibility of the developed setup also allows performing stochastic nucleation studies to estimate the nucleation kinetics under silent and sonicated conditions. The experiments reveal that very high nucleation rates, small crystal sizes, narrow size distributions and high crystal yields can be obtained with both setups when the crystallizing solution is exposed to high pressure field as compared to silent condition. It is concluded that transient cavitation of bubbles and its consequences are a significant mechanism for enhancing nucleation of crystals among several proposed in the literature. A preliminary study towards the development and design of a growth stage is finally performed. Flow pulsation is identified as a potential method to enhance radial mixing and narrow residence time distribution therefore achieving optimal conditions for uniform crystal growth. The results suggest that increasing values of Strouhal number as well as amplitude ratio improve axial dispersion. Helically coiled tubes are identified as potential structures to further improve fluid dynamic dispersion.
13
Nagy, Kevin David. "Catalyst immobilization techniques for continuous flow synthesis." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/70405.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, February 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 181-199).
Catalytic processes are ubiquitous in both research and industrial settings. As continuous flow processes continue to gain traction in research labs and fine and pharmaceutical chemical processes, new opportunities exist for implementing previously difficult catalytic transformations. The major goal of this thesis is to expand and evaluate techniques for immobilized catalyst systems relevant to continuous flow. Fundamental studies in characterizing mixing, dispersion, and residence time distributions in small scale continuous flow systems are also presented. Given the numerous benefits associated with studying chemical processes at small length scales, microfluidic devices are the tool of choice for most studies in this thesis. Thermomorphic solvents offer the potential for homogeneous catalytic processes with biphasic catalyst recovery and recycle. A major limitation of these processes is the number of synthetically useful thermomorphic solvent combinations demonstrated in literature. A screening program using the modified UNIFAC (Dortmund) activity coefficient model to evaluate phase splitting behavior has been developed to predict thermomorphic behavior. Calculation of 861 binary solvent combinations results in 43 potential thermomorphic and 44 biphasic solvent combinations. Extension of the program to ternary solvents resulted in a new class of ternary solvents that display thermomorphic behavior with tunable critical solution temperatures. Evaluation of thermomorphic processes as a general method is presented. Traditional catalyst immobilization techniques rely on covalent grafting and are well suited to continuous flow processing due to the strong interactions of the catalyst to the support. Fluorous physisorption, which relies on interactions between a fluorous support and a fluorous-tagged catalyst, is characterized and presented as an immobilization technique for flow chemistry. The use of a fluorous-tagged Co(III)-salen catalyst to effect the ring opening of epoxyhexane with water is presented. Application of the platform to the ring closing metathesis of N,Ndiallyltosylamide using a fluorous-tagged Hoveyda-Grubbs metathesis catalyst results in significantly accelerated loss of activity over time compared to the salen catalyst. Use of continuous flow selective adsorption reactors to enhance catalytic processes is presented. Continuous feeds of a homogeneous catalyst into a sorbent where the catalyst displays an affinity for the sorbent results in accumulation of the catalyst in the packed bed. The net effect is an enhancement in turnover frequency and turnover number relative to homogeneous flow. Application of this platform to a Lewis acid catalyzed Diels-Alder reaction results in an order of magnitude improvement in turnover frequency compared to batch and homogeneous flow.
by Kevin David Nagy.
Ph.D.
14
Kralj, Jason G. "Continuous flow separation techniques for microchemical synthesis." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/34164.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, February 2006.Includes bibliographical references (leaves 146-153).
Performing multistep microchemical synthesis requires many techniques from combining micromixers in series to the development of continuous microfluidic separation tools. Safety, high heat and mass transfer rates, and cost savings all continue to motivate microreactor development as a research tool, but many reactions generate a variety of (by)products including solid particles, immiscible fluids (gas and liquid), and miscible components requiring purification. We have endeavored to develop microfluidic systems which compliment existing microreactor technology, using forces that grow stronger with decreasing length scales such as electric fields and interfacial phenomena, and to use straightforward microfluidic mixers for kinetic studies of energetic material synthesis. Dielectrophoresis was used to study the continuous separation of polystyrene particles based on size. Essentially, a microfluidic particle "ratchet" was created using a soft-lithography microchannel and slanted interdigitated electrodes which provide a transverse force component on the particles. Experimental behavior agreed well with the model predictions, and 4 & 6 micron particles were continuously separated. Liquid-liquid extraction is another useful tool for microchemical synthesis and well-suited to small length scales because high mass transfer rates can be attained.
(cont.) However, emulsion formation and phase separation can provide significant challenges to continuous processing. To address breaking emulsions, a microfluidic tool was developed that uses AC E-fields to enhance coalescence of emulsified phases even where high surfactant concentrations are present, transforming the flow regime from disperse to slug. Phase separation of immiscible fluids is achieved by interfacial tension using porous membrane films which selectively wet only one fluid phase. An integrated mixer-contactor-separator was fabricated and used to separate fluids with low interfacial tensions due to miscible components. Solvent extraction and solvent switching were demonstrated using the device, which help enable continuous multistep microchemical synthesis. Kinetic studies and optimization of energetic material synthesis were performed with a relatively simple micromixers-in-series setup for diazotization and nucleophilic substitution reactions. Typical batch operation is performed in sub-ambient conditions with copper salts to precipitate the product and avoid degradation, resulting in a slow, hazardous, laborious synthesis. High heat and mass transfer enabled studying reaction temperatures at 300C to obtain kinetic parameters for both reaction steps.
(cont.) In addition, an optimum pH range for the substitution reaction was found, which will lead to a streamlined, faster process. Though still early in their development, these new tools will hopefully open the door to a range of new chemical syntheses and applications under conditions unachievable on the macroscale. Full integration of these technologies will enable multistep chemistry in microfluidic systems, which in turn will allow screening of new compounds, synthesis optimization, and reduction in chemical waste in a safe, efficient platform usable by chemists and biologists.
by Jason G. Kralj.
Ph.D.
15
Oliveira, Celina Rodrigues de. "Crystallization of vitamin D3 in continuous flow." Master's thesis, Universidade de Aveiro, 2016. http://hdl.handle.net/10773/21298.
Full textAbstract:
Mestrado em Engenharia QuímicaA vitamina D3 é um micronutriente essencial para o metabolismo do cálcio, sendo esta maioritariamente sintetizada na pele do ser humano, quando exposta a radiação UVB. Contudo, inúmeros factores têm vindo a reduzir a nossa exposição à luz solar, diminuindo assim os níveis de vitamina D3 no corpo humano a nível global e aumentando a preocupação por parte de diversas instituições médicas a nível mundial. Para superar esta deficiência em vitamina, a vitamina D3 tem sido adicionada à alimentação humana através de alimentos fortificados e de suplementos alimentares. Para satisfazer a procura da população em vitamina D3, este trabalho apresenta uma unidade de cristalização com dois estágios que opera em contínuo à escala micro. O objectivo deste trabalho é projectar e optimizar esta unidade de cristalização por forma a desenvolver uma unidade de produção de cristais de vitamina D3 mais económica, mais sustentável, e com elevado rendimento de cristais aproriados para aplicações farmacêuticas. O primiero estágio da unidade de cristalização projetada corresponde a uma coluna de vidro onde a nucleação é intensificada através de cristalização por evaporação e por adição de anti-solvente. Este cristalizador opera a 40 ºC e o caudal volumétrico é controlado manualmente. O segundo estágio é um cristalizador tubular onde a cristalização ocorre por redução da temperatura para promover o crescimento dos núcleos produzidos no estágio anterior. Esta é operada a 7 ºC e em 59 s de tempo de residência. Após o segundo estágio, um filtro está integrado no sistema para recolher os cristais de vitamina D3 sintetizados. Este trabalho está dividido em duas partes. A primeira abrange a optimização da unidade de cristalização, a qual foi conseguida estudando o efeito da razão volúmica entre o anti-solvente e o solvente no desempenho da cristalização. O melhor resultado foi obtido para a proporção volúmica de 3, a qual permitiu alcançar 52 % de rendimento absoluto e 60 % de eficiência de filtração. Adicionalmente, por forma a melhorar o rendimento e a eficiência de filtração, ensaios experimentais foram realizados onde a corrente de permeado (da filtração) foi reciclada. Porém, as melhorias esperadas não se verificaram, o que significa que ensaios experimentais adicionais são necessários para sustentar uma conclusão sólida relativamente ao efeito do reciclo no processo em estudo. A reprodutibilidade do processo desenvolvido e optimizado também necessita ser melhorada. A segunda parte corresponde à caracterização dos cristais de vitamina D3 produzidos durante os ensaios de optimização. Os cristais apresentam uma forma prismática e aglomeração significativa. A distribuição de tamanhos dos cristais é ampla, extendendo-se desde, aproximadamente, 0.25 μm a quase 500 μm. Adicionalmente, a estrutura dos cristais produzidos não corresponde à estrutura termodinamicamente mais estável. Excluindo o seu hábito, as características dos cristais produzidos não são adequadas para aplicações na indústria farmacêutica. No entanto, sugestões são apresentadas para melhorar ambas as características dos cristais e a optimização do processo.
Vitamin D3 is an essential micronutrient for calcium metabolism, which is mainly synthesized in the skin of the human organism when irradiated with UVB light. However, a variety of factors have been reducing our exposition to sunlight, and thus the levels of vitamin D3 in the body have been decreasing, rising the concern of numerous medical institutions worldwide. To overcome such vitamin deficiency, the vitamin D3 has been added to the diet through fortified food and dietary supplements. To address the population demands on vitamin D3, this project presents a two-stage crystallization unit that operates continuously at a microscale. The aim of this project is to design and optimize this crystallization unit in order to develop an economical and sustainable high yield production unit of vitamin D3 crystals suitable for subsequent pharmaceutical applications. The first stage of the designed crystallization unit corresponds to a glass column where nucleation is enhanced by evaporation and anti-solvent crystallization. This crystallizer operates at 40 ºC and the volumetric flow rate is manipulated manually. The second stage is a tubular crystallizer where a cooling crystallization takes place to further grow the nuclei generated in the previous step; it is carried out at 7 ºC and 59 s of residence time. At the end of the second stage, a filter is placed to collect the synthesized vitamin D3 crystals. This work is divided in two main parts. The first part comprehends the optimization of the crystallization unit, which was accomplished by studying the influence of the anti-solvent/solvent volumes ratio on the performance of the crystallization. The best results were obtained for the volume ratio of 3, where 52 % of absolute yield was achieved as well as 60 % of filter efficiency. Furthermore, other experiments were performed where the permeate stream (of the filtration) was recycled to improve both yield and filter efficiency. However, such expected improvements were not confirmed, which means that additional experiments are needed to support any reliable conclusion regarding the effect of recycling on the process. The reproducibility of the crystallization process developed and optimized needs to be improved as well. The second part corresponds to the characterization of the crystals produced during the optimization assays. The crystals exhibit a prismatic habit and a significant degree of agglomeration. The crystal size distribution is large, extending from ca. 0.25 μm to almost 500 μm. Furthermore, the obtained solid-state form is not the thermodynamically stable one. Besides the crystal habit, the properties of the obtained crystals are not yet suitable for a pharmaceutical application. Nonetheless, suggestions of improvement are presented for both crystals characterization and optimization of the crystallization process.
16
Porta, R. "STEREOSELECTIVE CATALYTIC REACTIONS UNDER CONTINUOUS FLOW CONDITIONS." Doctoral thesis, Università degli Studi di Milano, 2017. http://hdl.handle.net/2434/479336.
Full textAbstract:
This PhD Thesis deals with the application of different catalytic methodologies under continuous flow conditions. In particular, the combination of flow chemistry with different enabling technologies is explored.
In Chapter 1 the combination of continuous flow processes with the use of different solid supported chiral organocatalysts is described. The fabrication of chiral, packed-bed and monolithic, organocatalytic reactors and their use in stereoselective transformations are reported. The possibility to recycle the immobilized chiral catalysts is also discussed.
- In section 1.2 the use of polystyrene- and silica-supported chiral imidazolidinones to perform continuous flow stereoselective Diels-Alder cycloadditions and stereoselective aldehydes alkylation is studied.
- In section 1.3 the immobilization onto different materials of primary amines derived from Cinchona alkaloids and the application under flow conditions are explored.
- In section 1.4 chiral picolinamides for the continuous stereoselective reduction of imines with trichlorosilane are studied.
Chapter 2 describes the application of different synthetic strategies using flow micro(meso)-reactors, aimed to the synthesis of chiral active pharmaceutical ingredients or immediate advanced precursors of compounds of industrial interest. In particular,
- in section 2.2 the organocatalytic, stereoselective synthesis of (S)-Pregabalin and (S)-Warfarin within microreactors is investigated.
- Section 2.3 presents the continuous flow synthesis of primary amines through a metal-free reduction of nitro compounds with trichlorosilane.
- In section 2.4 a catalytic strategy for a multistep synthesis of chiral, biological active 1,2-amino alcohols using 3D-printed flow reactors is highlighted.
Chapter 3 covers the research work carried out during my research period in Aachen, Germany which was focused on the development of a new synthetic methodology using photoredox catalysis. In particular, the photocatalytic reductive coupling of imine with olefins for the preparation of -amino esters and its application under continuous flow conditions are discussed.
17
Lawrence, J. P. "Microfluidic tangential flow filter and continuous-flow reactor for bioprocess development." Thesis, University College London (University of London), 2015. http://discovery.ucl.ac.uk/1468842/.
Full textAbstract:
The development of new biocatalytic processes is hindered by the number of factors that must be investigated and optimised in order to create a robust and reproducible process, particularly where a novel enzyme is involved. It is therefore advantageous to perform process development experiments at micro scale, in order to reduce the material requirement for experimentation and increase experimental throughput by parallelisation. The initial focus of the thesis is on the design of a microfluidic tangential flow filter to test downstream processing conditions. The device was designed for reversible clamp sealing, allowing the simple integration of different filtration membranes, and the seal achieved with the device was shown to be robust up to internal pressures of 100 psi. The filtration device was applied to the recovery of L-erythrulose (ERY) from a synthesis reaction performed using transketolase (TK), where it was demonstrated that the enzyme could be fully retained using a commercially-available membrane, while ERY was able to permeate the membrane freely. The filtration device was joined in-line to the output of a T-junction reactor with a staggered herringbone mixer, used to perform the synthesis reaction. The filter was capable of continuously separating the ERY from the lysate mixture exiting the reactor over the course of several hours, producing 3.6 mg h-1 of pure ERY. A novel multi-input reactor (MIR) is also demonstrated for the purpose of intensifying ERY output, designed to overcome the effect of substrate inhibition on the TK enzyme by mimicking a fed-batch reactor. Feeding strategies were designed for the conversion of various concentrations of the less inhibiting substrate hydroxypyruvate (HPA) and tested in the MIR. A 4.5-fold increase in output concentration and a 5-fold increase in throughput were achieved compared with the single input reactor used in previous experiments. However, conversion in the MIR was reduced at higher concentrations, suggesting that the reaction in the MIR was being inhibited by the evolution of carbon dioxide.
18
Kriel, Johannes Nicolaas. "Non-perturbative flow equations from continuous unitary transformations." Thesis, Link to the online version, 2005. http://hdl.handle.net/10019/1076.
Full text
19
Wittering, Kate. "Multi-component crystallisation in the continuous flow environment." Thesis, University of Bath, 2016. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.687312.
Full textAbstract:
The research described in this thesis was carried out as part of the EPSRC National Centre in Continuous Manufacturing and Crystallisation (CMAC), whose vision is to accelerate the adoption of continuous manufacturing processes for the production of high-value chemical products. Results focus upon the crystallisation of multi-component molecular complexes (MMCs), in particular co-crystals, an important class of potential functional molecular materials. MMCs are commonly discovered through small scale batch solvent evaporation, a method that provides little control over the crystallisation process, often yields only small quantities of crystalline material which may not be phase pure and is not generally scalable. Methods have been developed to help translate traditional small scale batch co-crystallisation of MMCs to selective continuous co-crystallisation processes. The co-crystal system urea-barbituric acid (UBA) has three polymorphs, previously identified in the literature and was selected as a candidate for transfer to continuous crystallisation as its polymorphism offers a development challenge in being able to achieve selectivity of solid products through by various crystallisation processes. Chapter 4 describes small scale crystallisation studies of UBA using evaporation, cooling and mechano-crystallisation techniques, demonstrating that UBAI is the more prevalent polymorph. Solid state and solubility analysis of the isolated UBA polymorphs are detailed; these data provide information on the energetic relationship between the polymorphs highlighting the similarity in energy of UBAI and UBAIII, and the metastable nature of elusive UBAII. In addition the polymorphic nature of the barbituric acid starting material has been investigated with samples from different suppliers proving to consist of different polymorphs. As well as being important in designing subsequent crystallisation processes, results from these studies corroborate work previously reported in the literature Chapter 5 describes how these results have been used in development of continuous crystallisation experiments using Mixed-Suspension Mixed-Product Removal (MSMPR) with a cascade of three stirred tank reactors, while Chapter 6 investigates flow crystallisation of UBA using the Continuous Oscillatory Baffled Crystalliser (COBC) and the Kinetically Regulated Automated Input tubular flow Crystalliser (KRAIC). The KRAIC was designed and constructed as part of this research. The continuous crystallisation experiments presented in Chapters 5 and 6 demonstrate the selective continuous co-crystallisation of UBAI across all three continuous crystallisation platforms. In Chapter 7 a range of novel co-crystalline MMCs is presented, with structural determinations, using single crystal X-ray diffraction, coupled with characterisation of properties and crystallisation characteristics; these studies emphasise the physical property advantages of MMCs and in some cases their potential for future translation to continuous crystallisation.
20
Weeranoppanant, Nopphon. "Integrated continuous-flow chemistry enabled by multistage separations." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/106127.
Full textAbstract:
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Chemical Engineering, 2016.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 79-85).
Flow chemistry is becoming an accepted method of continuous synthesis with its considerable advantages over batch chemistry, such as smaller infrastructure, faster production, and safer operation for aggressive reactions or extreme conditions. However, to realize the full benefits of flow chemistry in multi-step reactions, continuous work-up techniques are needed. They will eliminate intermediate batch work-up steps that are often inefficient and time-consuming. This thesis describes the development of continuous liquid-liquid extraction and evaporation techniques along with their integration in multistep reaction sequences and purification on the mL/min scale. Fully-integrated syntheses for active pharmaceutical ingredients (APIs), lidocaine and fluoxetine, were studied in detail. These two examples represent two different strategies for integrating multistep reactions. Sequential reactive steps in the lidocaine synthesis were designed to be compatible without any separation, while in-line purification, liquid-liquid extraction, was required for the fluoxetine synthesis. The key outcome of this work was the construction of a compact, reconfigurable system for manufacturing four different APIs, at throughput of hundreds to thousands dosages per day. The system represents a significant advance in continuous manufacturing by demonstrating feasibility of facility decentralization and on-demand production. Another significant accomplishment of this thesis is the development of multistage liquid-liquid extraction using liquid-liquid membrane-based separators that enable highly efficient continuous extraction. While previous efforts have demonstrated a single stage or, at most, a few stages in crosscurrent configuration, the objective was to build a countercurrent extraction setup in the context of laboratory scale (i.e. mL/min). The setup was made possible with an integrated pressure control element, allowing non-precise interstage pumping to be employed. This setup was found effective for a wide range of industrially-relevant applications, from multicomponent solvent recovery to in-line removal of phase transfer catalysts. The thesis provides opportunities for future directions. For example, improvement in unit operations, such as pumping, solid handling, evaporation, and process control, will be needed to reach the potential of flow synthesis. The countercurrent extraction setup can be automated for faster screening and optimization of extraction conditions as well as be applied to complex processes, such as reactive extraction and enantioseparation.
by Nopphon Weeranoppanant.
Ph. D.
21
Bartlett, Bruce. "Flow equations for hamiltonians from continuous unitary transformations." Thesis, Stellenbosch : Stellenbosch University, 2003. http://hdl.handle.net/10019.1/53428.
Full textAbstract:
Thesis (MSc)--Stellenbosch University, 2003.ENGLISH ABSTRACT: This thesis presents an overview of the flow equations recently introduced by Wegner. The little known mathematical framework is established in the initial chapter and used as a background for the entire presentation. The application of flow equations to the Foldy-Wouthuysen transformation and to the elimination of the electron-phonon coupling in a solid is reviewed. Recent flow equations approaches to the Lipkin model are examined thoroughly, paying special attention to their utility near the phase change boundary. We present more robust schemes by requiring that expectation values be flow dependent; either through a variational or self-consistent calculation. The similarity renormalization group equations recently developed by Glazek and Wilson are also reviewed. Their relationship to Wegner's flow equations is investigated through the aid of an instructive model.
AFRIKAANSE OPSOMMING: Hierdie tesis bied 'n oorsig van die vloeivergelykings soos dit onlangs deur Wegner voorgestel is. Die betreklik onbekende wiskundige raamwerk word in die eerste hoofstuk geskets en deurgans as agtergrond gebruik. 'n Oorsig word gegee van die aanwending van die vloeivergelyking vir die Foldy-Wouthuysen transformasie en die eliminering van die elektron-fonon wisselwerking in 'n vastestof. Onlangse benaderings tot die Lipkin model, deur middel van vloeivergelykings, word ook deeglik ondersoek. Besondere aandag word gegee aan hul aanwending naby fasegrense. 'n Meer stewige skema word voorgestel deur te vereis dat verwagtingswaardes vloei-afhanklik is; óf deur gevarieerde óf self-konsistente berekenings. 'n Inleiding tot die gelyksoortigheids renormerings groep vergelykings, soos onlangs ontwikkel deur Glazek en Wilson, word ook aangebied. Hulle verwantskap met die Wegner vloeivergelykings word bespreek aan die hand van 'n instruktiewe voorbeeld.
22
Plaza, Dorota. "Continuous flow processes for catalytic upgrading of biofeedstocks." Thesis, University of Warwick, 2014. http://wrap.warwick.ac.uk/66188/.
Full textAbstract:
This thesis is dedicated to continuous flow processes for the catalytic transformation of biofeedstocks into fine and speciality chemicals. Four processes, namely epoxidation and ethenolysis of a bio-waste triglyceride, reduction of artemisinin and etherification of dihydroartemisinin were developed under batch and flow conditions. First, an epoxidation reaction was studied using a modified WVI/PV/H2O2/PTC catalyst complex. The reaction proceeded with high selectivity to oleic epoxide (86 %) and high conversion (100 %) towards the epoxidation reaction in both, batch and flow systems. The enthalpy of epoxidation of cocoa butter was found to be mildly exothermic at -168 kJ mol-1. Space time yield, a key process parameter, in both the systems were similar. The epoxidation of cocoa butter was controlled under both batch and flow conditions by mass transfer and chemical reaction. Second, the ethenolysis of cocoa butter under batch conditions was optimised in terms of catalyst, solvent, temperature and pressure. The M11 catalyst proved to be the most active at room temperature and 2 bar ethylene pressure in THF solvent. The optimized system was transferred to a continuous membrane contactor system. A high yield of decene and 1,4-decadiene were achieved, 44.5 % in total, for a residence time of 59 min at 40 ℃ and ethylene pressure of 6 bar. Third, the stoichiometric reduction of artemisinin to dihydroartemisinin (DHA) was successfully transferred from batch to continuous flow conditions with a significant increase in productivity and an increase in selectivity. A DHA space-time-yield of up to 1.6 kg h-1 L-1 was attained, which represented a 42-fold increase in throughput compared to the conventional batch process. Finally, a highly active heterogeneous catalyst was found for the etherification of dihydroartemisinin to a pharmaceutical API artemether. Using the QuadraSil catalyst allowed us to eliminate one step in the reaction workup. A comparative Life Cycle Assessment of both reduction and etherification reactions showed advantages of the flow process over the optimized literature batch protocols. The results of the LCA highlight the significance of solvents in pharmaceutical manufacture and the advantage of flow technology, enabling small solvent inventories to be used.
23
Schotten, Christiane. "Investigating multistep continuous flow processes using diazonium salts." Thesis, Cardiff University, 2018. http://orca.cf.ac.uk/113812/.
Full textAbstract:
This thesis describes the investigation of continuous flow processes that incorporate the generation and use of diazonium salts. In this manner, processes for the preparation of triazenes, indoles and acridones have been developed. Diazonium salts are potentially unstable and hazardous and have to be handled with care. The use of continuous flow processes enables the safe synthesis avoiding accumulation of large quantities. This is due to the possibility to intercept intermediates at a precise point in time within a closed system. Diazonium salts were prepared via in situ diazotization of anilines with isoamylnitrite. Triazenes were formed via the interception of diazonium salts with secondary amines. The process had to be carefully developed to avoid clogging and fouling of the reactor. 26 examples have been prepared. The thermal behavior of 13 triazenes has been compared to their corresponding tetrafluoroborate diazonium salts, which has shown they are significantly more stable. In addition, VT NMR analysis has been performed to explore restricted rotation around the triazene bond. Further developments have found that indoles can be prepared via reduction of diazonium salts to their corresponding hydrazine with ascorbic acid and subsequent Fischer indole reaction in a microwave reactor. The use of such a hybrid, machine assisted approach has enabled the formation of a library of indoles. In this manner, 33 examples have been synthesised including the drug Zolmitriptan and nine of its analogues. The formation of acridones from benzyne and anthranilates has been investigated. Benzyne was prepared via the thermal decomposition of benzenediazonium-2-carboxylate. The compound decomposes above ambient temperatures and is known to be explosive when dry. The formation of benzyne has been investigated using the Diels- Alder reaction with furan as a model reaction and then conditions were applied to a range of substrates to investigate the scope. Problems with solubility of starting materials, diazonium salts and products were encountered and partially solved through the screening of different solvents. Finally, an exothermic reaction was investigated under continuous flow reactions. Commercially available thermocouples and in line NMR analysis were used to facilitate process optimisation. The exothermic reaction explored was the reduction of TMSCF3 to TMSCF2H with NaBH4. The exotherm was monitored using external, commercially available thermocouples to realise the development of a safe reaction regime. The incorporation of in situ NMR measurements has allowed realtime assessment of reaction conversion as a correlation to the exotherm. With the combined monitoring approaches a safe scale up process has been established. A hybrid flow - batch approach was used to scale up the reaction and increase the space time yield compared to the previously reported batch reaction.
24
Sagandira, Cloudius Ray. "Exploring acyl azides chemistry in continuous flow systems." Thesis, Nelson Mandela Metropolitan University, 2017. http://hdl.handle.net/10948/12065.
Full textAbstract:
Organic azides are important in the synthesis of many target molecules of great use in fine chemical and pharmaceutical production. The use of this class of compounds is however limited due to their hazardous nature and many safety concerns, as they are highly exothermic. Micro reactors can handle exotherms extremely well, due to the inherent high surface area to volume ratio, unlike the conventional batch process. This dissertation therefore aims to investigate the safe application of micro reactors in acyl azide chemistry.With this in mind, Chapter 1 provides a comprehensive background on organic azides, reaction calorimetric studies, flow chemistry technology (micro reactors) and their theoretical advantages. This chapter also discusses the preparation of organic azides in continuous flow systems and scaling up in continuous flow systems. Chapter 2 illustrates and discusses multivariate optimisation of benzoyl azide synthesis as a model reaction, synthesis of other acyl azides using the model reaction optimised conditions and multistep synthesis of carbamates, amides and amines in continuous flow systems via the Curtius rearrangement of benzoyl azide formed in situ from benzoyl chloride and sodium azide. The chapter also discusses process hazards analysis and evaluation of benzoyl azide synthesis and decomposition using calorimetric studies. It also investigates and discusses the effects of different mixing regimes and channel sizes on scale up. Chapter 3 has comprehensive experimental details for the whole dissertation with Chapter 4 providing the concluding remarks and future work recommendations.
25
Sinha, Asish Kumar. "Melt flow and cleanliness in continuous casting tundishes /." The Ohio State University, 1990. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487686243820661.
Full text
26
Pereira, Fiona Marie. "Continuous and segmented-flow microfluidics for biomolecular analysis." Thesis, Imperial College London, 2012. http://hdl.handle.net/10044/1/9302.
Full textAbstract:
Segmented flows in microfluidics have attracted much recent attention. Of particular interest is the use of nanolitre droplets as interface tools in microfluidics. A droplet interface connects techniques while leaving them sufficiently independent of each other; a task that difficult to perform within a continuous flow system. The first part of this thesis is dedicated to sample preparation and analysis in continuous flow microfluidic systems. The polymerase chain reaction (PCR) is investigated, using electroosmotic flow to transport the sample across various temperature zones. Additionally, a novel sieving matrix for electrophoretic separation of dsDNA fragments and PCR amplicons on microchip and capillary is demonstrated. The second part of this thesis focuses on interfacing segmented and continuous flows. Two novel interfaces are described and demonstrated. The first interface connects droplet flows and a chip-based electrophoresis device. Using this interface, samples or reactions performed in droplets can be directly transferred to a separation channel without suspending the separation. This allows multiple samples to be analysed in a single separation channel, without cross contamination between droplets. Consequently, PCR reactions and dsDNA calibration ladders can be prepared in droplet format and analysed in high throughput. The second interface links nano-liquid chromatography and MALDI mass spectrometry. Droplet fractionation post nano-LC separation is used to preserve resolution between separated bands. The droplets are subsequently delivered to a MALDI plate for mass spectrometric analysis by removing the continuous oil phase using a hydrophobic oleophilic membrane. The tools developed here reduce manual intervention and provide a link between multiple analytical techniques involved in biomolecule analysis. These innovations will improve reproducibility and reduce cross-contamination between samples.
27
Cullen, Christopher J. "Application of continuous-flow nanoreactors to catalyst screening." Thesis, Imperial College London, 2008. http://hdl.handle.net/10044/1/11987.
Full text
28
Veremieiev, Sergii. "Gravity-driven continuous thin film flow over topography." Thesis, University of Leeds, 2011. http://etheses.whiterose.ac.uk/1688/.
Full textAbstract:
This thesis is directed primarily at a systematic theoretical investigation of gravity-driven thin film flow over various topographical features, the effect of inertia being of particular interest. The problem is solved using a hierarchy of models based, in order of decreasing complexity, on (i) the full Navier-Stokes system of equations; (ii) a depth averaged form of the latter; (iii) the lubrication equations. Every effort has been made to solve the underlying discrete equation set in each case efficiently using state-of-the-art solution strategies, thus guaranteeing accurate and mesh-independent predictions. The solution of models (ii) and (iii) centres on the use of a multigrid methodology together with automatic, error controlled, time-stepping and the proper treatment of any associated nonlinear advective terms. A discrete analogue of model (i), for both two- and three-dimensional flows, is obtained using a finite element formulation with the free surface parametrised via the method of spines and the system solved using a parallel multifrontal method together with a memoryefficient out-of-core storage approach. A comprehensive set of results is presented for flow over both one- and twodimensional topography, generated using models (ii) and (iii); the predictions obtained are contrasted with each other and compared with existing related experimental data. The free-surface disturbance arising for the problems investigated is revealed to be influenced significantly by the presence of inertia which leads to an increase in the magnitude and severity of the resulting capillary ridge, surge and trough formations present. A complementary exploration, using model (i) is undertaken which reveals the attendant internal flow structure. It shows that two-dimensional flow over spanwise topography and three-dimensional flow over localised trench topography can lead to different internal, inertia dependent, flow topologies; findings that are consistent with previously reported results for the well-known lid-driven cavity problem. Finally, the effect of a normal electric field on the free-surface disturbance generated by inertial thin film flow over topography is investigated using model (ii) coupled with a Fourier series separable solution of Laplace’s equation for the electric potential. Results for both two- and three-dimensional flow reveal that a significant electric field strength can be used to effectively planarise the free-surface capillary ridges and depressions that arise. The two-dimensional solutions obtained are consistent with those reported elsewhere for the case when inertia is neglected and highlight the importance attached to choosing an appropriate means of embodying the latter. Furthermore, the novel results generated for three-dimensional flow demonstrate that as Reynolds number increases, larger electric field strengths are required to planarise the associated free-surface disturbance.
29
Vicens, Jim. "Continuous Zeolite Crystallization in Micro-Batch Segmented Flow." Digital WPI, 2018. https://digitalcommons.wpi.edu/etd-theses/1307.
Full textAbstract:
Zeolites are porous aluminosilicates that occur both naturally and synthetically, having numerous applications in catalysis, adsorption and separations. Despite over a half century of characterization and synthetic optimization of hundreds of frameworks, the exact mechanism of synthesis remains highly contested, with crystallization typically occurring under transport-limited regimes. In this work, a microcrystallization reactor working under segmented oscillatory flow has been designed to produce a semi-continuous flow of zeolite A. The fast injection of the reactants in a mixing section forms droplets of aqueous precursors in a stream of paraffin, dispersing microdroplets and avoiding any clog from occurring in the system. The crystallization occurred in the system at atmospheric pressure and isothermal conditions (65ºC). This allowed for a rather slow crystallization kinetics which was important to study and highlight the different crystallization mechanisms between flow and batch synthesis. The morphology, size distributions, crystallinity, and porosity were examined by ex-situ characterization of the samples by scanning electron microscopy, X-ray diffraction, Raman spectroscopy, and N2 Physisorption to support the conclusions drawn. The size distribution of the particles achieved in the flow reactor was conclusively narrower than the distribution achieved in the batch reactor. The average size of the crystals for both synthesis methods is reported as 400 nm and the crystallinity achieved was comparable between the two. However, the morphology was quite different between the two systems, the flow products having a much higher mesoporosity due to the presence of crystal aggregates at high crystallinity when compared to the batch crystals. Finally, extended crystallization times leads to a decline of the crystallinity of the product, which might be explained by the metastable state of zeolites in solution.
30
Barestrand, Henrik, and Tobias Forslund. "Numerical & physical modelling of fluid flow in a continuous casting mould : Flow dynamics studies for flexible operation of continuous casters." Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-59847.
Full textAbstract:
The current demands on Swedish steel industry to produce low quantity batches of specialized products requires research on steel casting processes. There are several physical processes that need be taken into account for this problem to be viewed in full light such as thermal-processes, solidification and fluid dynamics. This work focuses on the fluid-dynamics part; more specifically, the dependence of flow quality within the caster on nozzle and mould geometry. The simulations are carried out using a scale-resolving method, in specific LES (Large Eddy Simulation) which is coupled with a DPM (Discrete Phase Model) to model Argon behaviour. The results of these simulations are presented and validated against physical experiment and data from industrial trials. Conclusions are drawn regarding optimal nozzle types in respect to different mould geometries. The mould eigenfrequencies are shown to exhibit a connection with the casting velocity. This results in so called sweet spots in casting velocity where flow irregularities due to sloshing is minimal. It is shown that the mountain type nozzle is preferable for smaller geometries whilst comparatively larger geometries benefit from a cup type.FLOWFLEX CC
31
Rivard, Stephanie. "Evaluation of Continuous Flow Constructed Wetlands Treating Swine Waste." TopSCHOLAR®, 1997. http://digitalcommons.wku.edu/theses/352.
Full textAbstract:
The ability for wetlands to purify contaminated water is not a new concept. Natural wetlands have been cleansing water within our environment for ages. After studying the process of natural wetlands the same concept was applied to municipal waste. It is the success of constructed wetlands treating municipal waste that created the new idea for the application of a wetland system to treat wastewater from livestock facilities. Through proper design and management, constructed wetlands may be useful for reducing the nutrient concentration of waste (Rieck el al., 1996). Taking into consideration the higher nutrient loads of livestock waste, the same basic idea of constructed wetlands used for municipal waste is being utilized to protect public water sources from contamination of livestock wastes. In this study a constructed wetland (total recycle) built for the purification of swine waste was evaluated. In cooperation with Pig Improvement Company of Allen County, Kentucky, water samples were collected from the nine connected cells making up the wetlands created at The Dogwood Ridge Farm. After collection of the samples, they were analyzed at the Western Kentucky University Environmental Laboratory. Samples were tested for levels of the following parameters: • Ammonia Nitrogen • Nitrate Nitrogen • Total Phosphorus • Biological Oxygen Demand • Total Suspended Solids • Total Dissolved Solids • Fecal Coliform • Conductivity • Mineral Elements The data in this report accounts for seven sample dates throughout 1996. Samples were also collected for three additional months prior to the first sample date in which data is reported, although these dates are considered to be a part of the initial start up phase for the testing period. Sample dates within the start up phase are not included among the results. With greater concern directed towards higher water quality standards, there is the need to eliminate any activities resulting in non-point source pollution (NPS). Livestock waste is considered one of the leading causes of NPS pollution which has created this awareness for better waste management. As traditional waste treatment equipment is commonly too expensive for the average livestock producer, constructed wetlands are proving to be an affordable, environmentally friendly, and manageable solution for livestock waste treatment.
32
Matys, Paul. "Fluid flow and heat transfer in continuous casting processes." Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/28504.
Full textAbstract:
A three-dimensional finite difference code was developed to simulate fluid flow and heat transfer phenomena in continuous casting processes.
The mathematical model describes steady state transport phenomena in a three dimensional solution domain that involves: turbulent fluid flow, natural and forced convection, conduction, release of latent heat at the solidus surface, and tracing of unknown location of liquid/solid interface.
The governing differential equations are discretized using a finite volume method and a hybrid central, upwind differencing scheme. A fully three-dimensional ADI-like iterative procedure is used to solve the discretized algebraic equations for each dependent variable. The whole system of interlinked equations is solved by the SIMPLE algorithm.
The developed computer code was used for parametric studies of continuous casting of aluminum. The results were compared against available experimental data. This numerical simulation enhances understanding of the fluid flow and heat transfer phenomena in continuous casting processes and can be used as a tool to optimize technologies for continuous casting of metals.Applied Science, Faculty of
Mechanical Engineering, Department of
Graduate
33
Baker, Alastair. "Flow reactors for the continuous synthesis of garlic metabolites." Thesis, Cardiff University, 2015. http://orca.cf.ac.uk/86704/.
Full textAbstract:
Garlic secondary metabolites are organosulfur compounds that possess prophylactic properties. The chemical composition of garlic oil extracts consists of a combination of these compounds. The instability of a major component, allicin 5, limits the commercial viability of garlic oil extracts. The synthesis of garlics organosulfur compounds has been performed in batch reactors. In this thesis, flow reactors were utilised to improve the throughput, reduce the operating conditions. The thermolysis of allicin 5 is the solitary approach to produce the garlic metabolite, ajoene 14. Ajoene 14 has greater stability compared to allicin 5 that possesses interesting biological activity. The primary three-step synthesis investigated consisted of dialkyl polysulfide synthesis, subsequent oxidation and finally the terminal thermolysis. In addition, other garlic metabolites have also been produced. The synthesis of unsymmetrical monosulfides and their subsequent oxidation was investigated using novel heterogeneous packed-bed flow reactors. The stable amino acid, alliin 15, is the precursor of allicin 5. Alliin 15 was also synthesised in homogeneous flow mode. The telescoped synthesis of alliin 15 was successfully completed using a semi-batch reactor. Development of novel approaches to synthesise garlics organosulfur compounds is reported in this thesis. Finally, the flow reactor systems, experimental details and characterisation of the compounds are described.
34
Kühn, Sebastian [Verfasser]. "Continuous traffic flow models and their applications / Sebastian Kühn." München : Verlag Dr. Hut, 2015. http://d-nb.info/1076437591/34.
Full text
35
Glasgow, Graeme D. E. "Small continuous flow rate fluctuations in rapid gravity filtration." Thesis, Loughborough University, 1998. https://dspace.lboro.ac.uk/2134/11365.
Full textAbstract:
Rapid gravity filters used in the treatment of drinking water are subject to small continuously occurring flow rate fluctuations known as surges. Large, step changes in the rate of flow have been shown to have a detrimental effect on filtrate quality. However, less is known about the effects of surging flow on rapid filter performance. Measurements by previous researchers have found that surges from 2 to 10 % of the flow rate are common and can occur as many as one hundred times per minute. It has been suggested that surging may significantly influence rapid filter performance but the effect has yet to be confirmed under well-controlled conditions and the mechanisms critically examined. Measurements taken by this author at local water treatment plants confirmed the presence of surging flow in the rapid gravity filters of a similar nature to other researchers' findings. Evidence suggested the degree of surging present was related to the design of the filtrate piping and some design recommendations are made on this basis. Two rapid gravity filters were developed in the laboratory to investigate the influence of surging flow on filter performance. The filters were constructed from Perspex pipe and comprised 600 mm of 0.5 to 1.0 mm filter sand. The filters were operated at 30°C at an approach velocity of 8.0 metres per hour with a test suspension of PVC particles. Reproducible performance was established before applying surges to one filter only. A range of surging characteristics similar to those observed at full-scale plants was applied during the test programme. Measurements of head loss and turbidity were taken at a range of depths within the filter media periodically during each test. Samples were collected for particle size distribution analysis from selected tests. The surging flow was found to inhibit the performance of the laboratory filters. The fluctuations in flow rate were found to reduce the removal efficiency of turbidity' and retard the rate of head loss development. The surges were found to inhibit the removal of all particle sizes present in the test suspension. The magnitude of the effect on filter performance was found to be dependent on the magnitude and frequency of occurrence of the surges applied. The experimental results obtained suggest that surging does have an effect on full- scale rapid filter performance and has implications for drinking water quality.
36
Gooden, Peter N. "Continuous-flow reactions of diols in supercritical carbon dioxide." Thesis, University of Nottingham, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.580384.
Full textAbstract:
The continuous O-alkylation of alcohols and diols has been studied over solid acid catalysts in supercritical carbon dioxide, scC02, to examine the potential for performing highly selective, clean etherification reactions. An introduction to the application of these reactions with respect to green chemistry is presented in Chapter 1, focusing in particular, on the industrial use of alternative solvents and solid acid catalysts. The apparatus, experimental methods and analytical techniques are described in Chapter 2, and their use is illustrated with reference to the acid catalysed esterification of 1,6-hexanediol in SCC02. Chapter 3 details the etherification of the symmetrical diol substrate, 1,6-hexanediol, which was investigated using primary alcohols (MeOH, EtOH and n-PrOH) as alkylating agents. This system showed remarkable pressure tunability with the desymmetrised mono-ether being favoured at high system pressures, and the bis-ether formed selectively at low pressure. When studying other diols, intermolecular etherification was only observed at primary OH groups, secondary OH groups preferentially underwent elimination or formed cyclic ethers when the substrate structure allowed. The etherification of the commercially important di-hydroxy substrate, isosorbide, was also attempted in scC02, and the results are presented in Chapter 4. The OH groups of isosorbide, an unsymmetrical molecule, exhibited vastly differing reactivity, and achieving good selectivity to the desired product, dimethyl isosorbide (DMI), proved difficult. In addition, the formation of dimethyl ether (DME), an undesirable by-product formed from unreacted MeOH, means that these processes currently have limited commercial potential. Dimethyl carbonate (DMC) has also been studied as a potentially benign reagent for the formation of methyl ethers in scC02, shown in Chapter 5. DMC was observed to decompose over acid catalysts to form DME and C02, but gave excellent yields of the methyl ethers of various substrates. Temperature programmed experiments revealed that the decomposition reaction greatly assisted the methylation of the substrate. This system shows much greater potential for commercial application as highly concentrated substrate solutions can be converted with high yields and selectivities. A brief summary of the conclusions drawn from this Thesis is given in Chapter 6. This Chapter evaluates how well the initial Project aims were met and proposes some future directions for this area of research.
37
Smith, Laura Katherine. "Synthesis of value-added intermediates by continuous flow technology." Thesis, Durham University, 2018. http://etheses.dur.ac.uk/12526/.
Full textAbstract:
We present three projects linked by our use of continuous flow chemistry in the synthesis of organic intermediates. The first is the synthesis of 1,1'-spirobiindane-7,7'-diol (SPINOL) in 6 steps and 32% overall yield. The synthesis has been improved over the previous literature protocols as it is safer, scalable, and higher-yielding, with better robustness and reproducibility. We introduce two attempts towards the enantioselective synthesis of SPINOL. In the second project, we have developed a flow process based on the Vapourtec reactor to synthesise coumalic acid and methyl coumalate from malic acid in concetrated sulfuric acid. A new heated rotating flow reactor is also presented for the intensified synthesis of coumalic acid, a valuable intermediate in organic synthesis derived from biorenewable sources of malic acid. Methyl coumalate has been used in two Diels-Alder reactions where the products have applications in molecular electronics and organic light-emitting diodes. Finally, the Darzens reaction for the synthesis of epoxides is presented here for the first time in flow, providing access to a range of benzaldehyde-derived products, including precursors to the pharmaceutical compound ibuprofen.
38
Nieves, Remacha María José. "Microreactor technology : scale-up of multiphase continuous flow chemistries." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/91068.
Full textAbstract:
Thesis: Sc. D., Massachusetts Institute of Technology, Department of Chemical Engineering, 2014.Cataloged from PDF version of thesis.
Includes bibliographical references.
Microreactors have been demonstrated to provide many advantages over conventional process technologies for the synthesis of chemical compounds and kinetic studies at the laboratory scale. High heat and mass transfer rates, rapid mixing, and higher selectivities and conversions can be achieved in these microdevices thanks to the small characteristic dimensions, enabling the synthesis of compounds that cannot be synthesized in conventional reactors. In the past years, efforts have been directed towards the application of microreactor technology for production purposes, especially in the pharmaceutical and fine chemicals industry. The challenge is how to get benefit of the transport rates inherent to microreactors while increasing the throughput for production applications. Two approaches to increase production rate are possible: a) scale-out by parallelization of units; b) scale-up by increase in channel size and flow rates. Scale-out would require thousands of units to achieve kg/min of production rates and development of very expensive and complex control systems to ensure identical operating conditions in each unit for a perfect and predictable overall reactor performance. On the other hand, scale-up by increase in channel size risks losing mass and heat transfer performance. The Advanced-Flow Reactor (AFR) manufactured by Corning Inc. combines both approaches being able to yield production rates of 10 - 300 g/min per module. If the AFR is demonstrated to perform efficiently and to be easily scalable, it may become an alternative for process intensification and transition from batch to continuous in the pharmaceutical and fine chemicals industry. Additional advantages include shorter process development times thanks to the scalability of the reactor modules, higher selectivities and yields, greener production processes, and possibility of introducing new chemistries. In this context, fundamental understanding of the hydrodynamics for multiphase systems is essential and critical for process development and scale-up purposes. The objective of this thesis is to study both experimentally and through computational fluid dynamic simulations the hydrodynamic characteristics of the AFR to demonstrate the capabilities of this technology using non-reactive (hexane/water) and reactive systems (carbon dioxide/water, ozone/alkene) at ambient conditions.
by María José Nieves Remacha.
Sc. D.
39
Duque, Ruben. "Supported ionic liquid phase catalysis in continuous supercritical flow." Thesis, University of St Andrews, 2013. http://hdl.handle.net/10023/3387.
Full textAbstract:
The separation of the expensive catalysts from the solvent and reaction products remains one of the major disadvantages of homogeneous catalytic reactions, which are otherwise advantageous because of their high activity, tuneable selectivity and ease of study. Ideally, the homogeneous reactions would be carried out in continuous flow mode with the catalyst remaining in the reactor at all times, whilst the substrates and products flow over the catalyst. The system we have been studying is one where the catalyst is dissolved in a thin film of an ionic liquid, and this is supported within the pores of a microporous silica. This supported ionic liquid phase (SILP) catalyst is then placed in a tubular flow reactor, similar to that used for heterogeneous reactions. The raw materials are then injected into the rig, pass through the reactor and the products and the raw materials that have not reacted are collected at the other end of the rig. Supercritical CO₂ is used to transport the raw materials and products along the catalyst bed, allowing a continuous flow mode with low leaching for both the catalyst and the ionic liquid. We have applied this procedure first to alkene metathesis catalysed by a ruthenium complex that has been especially designed to dissolve in 1-butyl-3-methyimidazolium triflamide (BMIM NTf₂), which was used as ionic liquid. Activity is observed for the ring closing metathesis of diethyl 2,2-diallylmalonate, but the catalyst is not stable, only allowing about 300 turnovers. This instability is attributed to the formation of Ru=CH₂ moieties, which dimerise to an inactive species. More success is achieved with internal alkenes such as 2-octene and especially methyl oleate. Self metathesis of methyl oleate continues for >10.000 turnovers over 10 h, with only small decreases in activity. The cross metathesis of methyl oleate with dimethyl maleate has also been studied. Cross metathesis dominates in the early stages of the reaction but the cross metathesis products diminish with time. Surprisingly, the catalyst does not deactivate since self metathesis of methyl oleate continues. The phase behaviour of the reaction was monitored and gave us an insight into the reasons for this change in selectivity. Methoxycarbonylation reactions in continuous flow proved to be a much more difficult process than the previous metathesis reactions. Higher catalyst loading was needed to reduce the reaction times. The first continuous flow reactions showed conversion predominantly, if not exclusive, of 1-octene isomerised products. The presence of ionic liquid (IL) in the SILP system was essential, otherwise the catalyst leached out of the reactor very quickly. Batch reactions showed that none of the studied parameters (absence of presence of either BMIM NTf₂, OMIM NTf₂, silica or CO₂) had any influence on the reaction, but when observing the results it was noticed that the reactions that gave the best results were performed in a close range of pressures between 55 and 70 bar, indicating that the reaction might be pressure dependent. Further continuous flow reactions in that range of pressures gave the best conversions to methoxycarbonylation products. Unfortunately, at these pressures and without CO₂ the reaction took place in a liquid phase and thus substantial IL and catalyst leaching was observed, causing a decrease in conversion and making the reaction not feasible under continuous flow conditions. Nevertheless, the catalyst system composed of Pd, 1,2-bis(di-tert-butylphosphinomethyl)benzene (DTBPMB) ligand and acid showed an excellent linear selectivity, usually higher than 90%, both in batch and continuous flow reactions. Hydrogenation reactions of dimethyl itaconate (DMI) and dibutyl itaconate (DBI) using Rh-MeDuPhos showed excellent activity and enantioselestivity in a batch mode. In a continuous flow mode IL leaching caused a decrease of the enantioselectivity. The best results were obtained when CO₂ was not present. On the other hand, the absence of CO₂ implied that the reaction was performed in a liquid phase and therefore abundant IL leaching was observed along with a decrease in the enantioselectivity. A study of the reaction behaviour when using CO₂ in its different phases (liquid, gas and supercritical) was carried out. Under supercritical conditions IL leaching was avoided but conversion was not observed. When using CO₂ in its liquid phase some conversion was observed and full conversion occurred in its gas phase, but abundant IL leaching caused a decrease in the enantioselectivity. Better results were obtained by immobilising a Rh-MeDuPhos catalyst onto alumina via heteropoly acids. The effect of pressure, H₂ flow and substrate flow were studied and the stability of the reaction in the long term was examined under optimal conditions. More than 12,900 TONs were achieved after 4 days of continuous reaction, with conversions higher than 90% during the 3 first days and e.e. higher than 99% during the 2 first days.
40
Zheng, Mingzhi. "The development of a continuous oscillatory flow meso reactor." Thesis, University of Cambridge, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.612058.
Full text
41
Smith, Christopher David. "The application of continuous flow technology for organic synthesis." Thesis, University of Cambridge, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.611296.
Full text
42
Anwar, A. "Continuous plastic flow synthesis and characterization of nanoscale bioceramics." Thesis, University College London (University of London), 2014. http://discovery.ucl.ac.uk/1458257/.
Full textAbstract:
The development and use of nanoscale biomaterials offer tremendous potential for future medical diagnosis and analysis. Various types of ceramic biomaterials (bioceramics) have been studied intensively for their potential in numerous biomedical applications. Among others, advances in the synthesis and characterisation of calcium phosphate (CaP) bioceramics have contributed much to this field. The growing demand for CaP bioceramics has stimulated research and production of materials suitable for biomedical applications such as implants. Among all the materials presented by the recent technology, only a very small fraction overcome biological and mechanical limitations rendering them suitable for use as a biomaterial. There is, therefore, a need to develop a clean synthesis methodology which could work under mild conditions to allow the synthesis of high purity, nanoscale bioceramic materials with a fine particle size and controlled surface area. The work in this thesis involves the use of a continuous plastic flow synthesis (CPFS) technology to synthesise various nano-scale bioceramics. Novel CPFS is a single step, continuous synthesis method for a stable, high purity phase-pure nanosized hydroxyapatite and other calcium phosphates at near ambient conditions (20°C to 80°C). The phase-pure HA nanoparticles obtained from this method possess a substantially superior high-temperature stability (1200°C), with remarkably high surface area (up to 264 m2/g) and the smallest particle size (20 nm) ever reported. These high surface area nanoparticles have a great range of applications for use in replacement of living hard tissues such as bone and teeth, as bone graft substitutes, injectable, coatings on metallic implants, as fillers or additives in commercial products, such as toothpastes; materials for the controlled release of drugs, or other controlled release therapies; reinforcements in biomedical composites, and in bone and dental cements. Other calcium phosphate phases (Brushite, β-TCP, CDHA and biphasic HA / β-TCP) were also obtained by changing the Ca:P ratio and pH of the precursor solutions. A variety of ion substituted calcium phosphates (Mg, Sr, Ba, Zn, Fe, Mn, Si, CO32-), nanocomposite materials (Fe3O4-HA, TiO2-HA) and surface modified organopolymer nano-dental composites have also been developed successfully by using CPFS. Furthermore, the process has the potential to offer high purity calcium phosphates because the reactor components are made of plastic and therefore will not cause contamination of the product with metals. The in vitro biocompatibility analysis indicate that these high surface area nano-sized bioceramics have better performance than commercial products and may have the potential to be used for biomedical applications where bone regeneration / replacement is required.
43
Wu, O. Y. "Continuous hydrothermal flow synthesis of lithium ion battery materials." Thesis, University College London (University of London), 2014. http://discovery.ucl.ac.uk/1455944/.
Full textAbstract:
There are a number of ways to improve the capacity of rechargeable batteries as suggested in the literature; carbon coating and reducing the particle size of the active material appear to be the most effective. In this work, the synthesis of pure phase LiFePO₄ nanoparticles was carried out directly in one step using the continuous hydrothermal flow synthesis (CHFS) system. Conventional synthesis methods require many steps and longer duration to obtain this cathode material. Microscopic data confirmed that the particles were successfully covered with an even carbon coating in situ where fructose was used. Through the use of the CHFS pilot plant, larger batches of the samples were made to allow thorough characterisation and electrochemical analysis. Coin cells were assembled from electrode sheets with the samples synthesised as the active material. The data collected from carbon coated LiFePO₄ cells showed good performance in terms of high C rate cycling and the specific capacity the cells provided. The results were comparable to those seen in the literature and amongst the highest of LiFePO₄ produced from a CHFS method. The doping of LiFePO₄ with manganese was successful as confirmed by various analysis techniques but it did not appear to have improved the electrochemical operation of LiFePO₄. However, upon certain doping levels the energy density of the material was approaching the theoretical value. The CHFS system was also used in an attempt to synthesise cathode materials optimised for electrochemical performance. For example, reaction conditions were tailored to produce samples with reduced particle sizes and samples intimately mixed with conductive carbon in situ. Further work will be to optimise the material ratio for electrodes and increase the amount of active material to be used. Also, to investigate fully how the morphology and thickness of an electrode can affect the performance of the cell.
44
Siguemoto, Érica Sayuri. "Continuous-flow microwave thermal processing of cloudy apple juice." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/3/3137/tde-25092018-075112/.
Full textAbstract:
Continuous-flow microwave heating is an alternative processing technology that can bring advantages to the pasteurization of food products, particularly, fruit-based beverages. This work aimed to study the continuous-flow microwave thermal processing of cloudy apple juice. Dielectric and electric properties of cloudy apple juices, obtained from different varieties and from an industrial plant, were determined from 500 to 3000 MHz and temperatures between 10 °C and 90 °C. At these frequencies, apple variety showed little influence and the permittivity decreased almost linearly with temperature. Inactivation kinetics of pathogen microorganisms (Escherichia coli O157:H7 and Listeria monocytogenes) and enzymes (polyphenol oxidase, peroxidase and pectin methylesterase) were studied and modeled to evaluate non-thermal effects of microwave radiation. For both processing technologies, it was possible to achieve a 5-log10 reduction of E. coli and L. monocytogenes, as recommended by the FDA. Microwave processing in comparison to conventional heating enhanced the microorganism inactivation in 18 out of 28 experiments. Predicted enzyme inactivation curves for pasteurization at 70 °C and 80 °C of the cloudy apple juice showed that pectin methylesterase has the highest thermal resistance and that there was no significant evidence of non-thermal microwave effects. A pilot scale unit used for pasteurizing fruit juices was evaluated and the process was modeled and simulated to determine the average time-temperature history. Mean residence times and dispersion parameters were obtained from internal volume measurements and residence time distribution experiments. Thermal processing experiments using water provided heat transfer coefficients as functions of Reynolds number and also microwave power absorption. Mathematical modeling was used to determine the temperature distribution along the product path and results were validated. Results showed that focused microwave heating provided the necessary temperature increase in a very short time, with a lethality contribution of only 0.7% as compared to 59-68% when using the conventional heat exchanger, which configures over-processing and can decrease product quality. Fresh cloudy apple juice was subjected to continuous flow microwave assisted pasteurization in a pilot scale unit at three processing temperatures (70 °C, 80 °C and 90 °C), two flow rate levels and two heating systems (conventional and focused microwave). Good results were obtained for polyphenol oxidase and peroxidase inactivation, but not for pectin methylesterase, which showed to be the most resistant enzyme. A comparative evaluation on quality changes was performed in cloudy apple juice samples pasteurized in the continuous-flow unit. Profile of volatiles of the microwave pasteurized apple juice was more similar to the nonpasteurized juice, in comparison with the conventionally pasteurized juice. However, total organic acids and total soluble sugar contents were not significantly different between both processing technologies. There was an increase of phenolic contents during processing of cloudy apple juice, possibly due to the extraction of phenolic compounds present in suspension of material. Furthermore, it was observed the same trend of antioxidant capacity by DPPH and ORAC methods. In conclusion, this PhD work presents the potential of the microwave-assisted pasteurization in cloudy apple juice regarding enzymatic, microbiological and quality aspects.Aquecimento de micro-ondas de fluxo contínuo é uma tecnologia de processamento alternativa que pode proporcionar vantagens para a pasteurização de produtos alimentícios, particularmente, bebidas à base de frutas. Este trabalho teve como objetivo estudar o processamento térmico de micro-ondas de fluxo contínuo em suco de maçã não clarificado. As propriedades dielétricas e elétricas dos sucos de maçã não clarificados, obtidos de diferentes variedades de maçãs e de uma planta industrial, foram determinadas entre 500 e 3000 MHz e temperaturas entre 10 °C e 90 ° C. Nessas frequências, a variedade da maçã apresentou pouca influência e a permissividade elétrica diminuiu quase linearmente com a temperatura. Cinéticas de inativação de microrganismos patogênicos (Escherichia coli O157: H7 e Listeria monocytogenes) e enzimas (polifenol oxidase, peroxidase e pectina metilesterase) foram estudadas e modeladas a fim de avaliar os efeitos não térmicos da radiação de micro-ondas. Para ambas tecnologias de processamento foi possível obter uma redução de 5-log10 de E. coli e L. monocytogenes, como recomendado pelo FDA. O processamento de micro-ondas em comparação com o aquecimento convencional aumentou a inativação dos micro-organismos em 18 dos 28 experimentos. As curvas de inativação enzimática preditas para pasteurização a 70 ° C e 80 ° C do suco de maçã mostraram que a pectina metilesterase possui a maior resistência térmica e que não houve evidência de efeitos não térmicos. Uma unidade de escala piloto usada para pasteurizar sucos de frutas foi avaliada e o processo foi modelado e simulado para determinar o histórico de tempo-temperatura. Os tempos médios de residência e os parâmetros de dispersão foram obtidos a partir de experimentos de distribuição do tempo de residência e volumes. Experimentos do processamento térmico utilizando água, como produto alimentício, forneceram coeficientes de transferência de calor em função do número de Reynolds e absorção de energia de micro-ondas. A modelagem matemática foi utilizada para determinar a distribuição de temperatura do percurso do produto, e posteriormente, foram validados. Os resultados mostraram que o aquecimento por microondas focalizadas proporcionou o aumento necessário da temperatura em um tempo curto, com uma contribuição de letalidade de apenas 0,7% em comparação a 59-68%, quando usado somente o trocador de calor convencional, o que configura sobre processamento, podendo diminuir a qualidade do produto. O suco de maçã fresco não clarificado foi submetido à pasteurização por micro-ondas em fluxo contínuo em uma unidade de escala piloto em três temperaturas de processamento (70 ° C, 80 ° C e 90 ° C), dois níveis de vazão e dois sistemas de aquecimento (convencional e micro-ondas). Resultados positivos foram obtidos para polifenol oxidase e peroxidase, mas não para a pectina metilesterase demonstrando ser a enzima mais resistente. Uma avaliação comparativa das mudanças de qualidade foi realizada em amostras de suco de maçã pasteurizado na unidade de fluxo contínuo. O perfil de voláteis do suco de maçã pasteurizado por microondas foi mais semelhante ao suco não pasteurizado em comparação ao suco pasteurizado convencionalmente. Entretanto, ácidos orgânicos totais e açúcares solúveis totais não foram significativamente diferentes no processamento por estas duas tecnologias. Houve um aumento de compostos fenólicos durante o processamento do suco de maçã não clarificado, possivelmente devido a extração de compostos fenólicos presentes no material em suspensão. Além disso, foi observado a mesma tendência na atividade antioxidante determinada pelos métodos de DPPH e ORAC. Em conclusão, este trabalho de doutorado apresenta o potencial da pasteurização por micro-ondas em suco de maçã não clarificado quanto aos aspectos enzimáticos, microbiológicos e de qualidade.
45
Starkey, Christopher L. "Continuous-flow hydrothermal and solvothermal synthesis of inorganic nanomaterials." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/37016/.
Full textAbstract:
Nanomaterials and nanotechnology are presently receiving high levels of interest which is aiding significant advancements to industrial and technological applications. New strategies towards nanoparticle synthesis are needed to produce high quality nanomaterials at industrially viable levels. This thesis presents the continuous flow hydrothermal and solvothermal synthesis (CFHSS) of a range of inorganic nanomaterials produced using a continuous-flow reactor designed at the University of Nottingham. The materials presented herein are currently industrially applicable or projected future trend materials. The aim is to widen the library of materials accessible via this relatively new synthetic strategy. It is mostly concerned with the development of the synthetic protocol towards specific materials and classes of materials, via both chemical and reactor configuration innovations, but additionally yields information about the chemical processes occurring within the reactor and how these can be controlled and exploited. This provides insight into not only the reactor but the field of CFHSS as a whole. Selected materials are subject to application based testing. With a fully industrial scale facility under construction, promising materials are trialled at pilot scale to assess the viability of the transfer of chemistry from laboratory to pilot scale with industrial scale production in mind. Chapter 1 provides an introduction to nanotechnology and nanomaterials in general, giving background to their unique properties and application. Traditional routes of synthesis are discussed, with particular focus then given to hydrothermal methods and continuous flow reactor design and nanoparticle production. Chapter 2 presents the characterisation techniques used in this thesis in terms of their theory and application. Application specific testing of the materials is explained in the relevant chapters. Chapter 3 reports the production of two different metal oxide materials, namely titania and doped titania photocatalyts, and barium strontium titanate nanopowders. Photocatalysis results are reported for the titania nanocrystals, and the barium strontium titanate nanopowders are produced in the first fully hydrothermal continuous flow synthesis at both laboratory and pilot scales to assess their viability for industrial scale production. Chapter 4 presents the development of the first continuous flow hydrothermal production of metal sulphide nanomaterials, via a general route using thiourea as the sulphur source. Full synthetic details and characterisation are discussed, together with information yielded about the materials and reactor and the implications this may have on future materials synthesis using CFHS and the Nottingham reactor. Chapter 5 details firstly batch hydrothermal and solvothermal synthesis of lithium iron phosphate materials to investigate the effect of a range of conditions on the reaction pathway and resulting products, followed by a translation of the knowledge learned into continuous flow hydrothermal and solvothermal reactions using the counter-current reactor. Scale up of the synthesis is achieved, together with electrochemical testing of selected products. Finally, chapter 6 provides general conclusions, summaries and outlooks for future work.
46
Channa, Sikandar Ali. "Synthesis of Ti-based nanoparticles in continuous flow microreactors." Thesis, Nantes, 2017. http://www.theses.fr/2017NANT4067/document.
Full textAbstract:
Des nanoparticules à basede titane dispersées dans des sols ou des gels avec une distribution de taille étroite permettent l’exacerbation des propriétés photochimiques de films photosensibles. Utilisés comme absorbeurs solaires dans les photobatteries, ils permettraient la conversion et le stockage de l'énergie solaire sous forme électrochimique. Dans ce travail, ces matériaux nanostructurés ont été produits par l'hydrolyse de TiOCl2,1.4HCl,7H2O dans du N, N-diméthylformamide (DMF),à l'intérieur d'un microréacteur afin d’assurer un meilleur contrôle en température et de confiner les fluides. En fonction du temps de vieillissement ou par étuvage, cette hydrolyse conduit à l’obtention de sols et de gels constitués de nanoparticules dispersées dans le solvant. La signature thermique de l’hydrolyse du TiOCl2en microréacteur observée par caméra infrarouge montre des instabilités de l'écoulement préjudiciables au contrôle de la taille des nanoparticules. Ceproblème a été finalement résolu par la pré-dilution de TiOCl2 avec du DMF. Par ailleurs, l'usage d'un procédé actif de mélange(champ électrique) a permis d'accélérer la réaction d’hydrolysedu TiOCl2pré-dilué ou pur pour certaines valeurs des conditions opératoires par ex. 7 VAC, 1MHz et ceci sans constater d’effets parasites (électrolyse de l’eau et formation d’ions Ti3+). Finalement,les nanoparticules produites ont été analysées en utilisant la technique de diffusion dynamique de la lumière. Une taille moyenne de nanoparticules s'étendant de 5 à 50 nma été obtenueavec du TiOCl2 pré-dilué, celle-ci dépendant de la vitesse d'écoulement, de l’âge des échantillons etde laprésence ou non de champ électriqueTi-based nanoparticles dispersed in solutions or gels with narrow size distribution may constitute innovative materials as absorbers in new devices such as photobatteries, allowing conversion and electrochemical storage of solar energy. In our work, these nanostructured materials were produced inside a microreactor by hydrolysis of TiOCl2 stabilized in aqueous HCl solution reacting with N,N-dimethylformamide (DMF). The use of a microreactor aims at providing a better temperature control and also a confinement of the reactive fluids. The thermal signature of the hydrolysis of TiOCl2 recorded by an infrared camera shows flow instabilities detrimental to the control of nanoparticle sizes. This problem was solved by the pre-dilution of TiOCl2 with DMF in the following proportion 0.52 DMF/Ti (16.7% vol. DMF).Otherwise, the use of an active mixing process based on an electric field implemented inside the microreactor has clearly shown the acceleration of the hydrolysis of TiOCl2without generating parasitic effects(water splitting,formation of Ti3+ions), if operating conditions are adequately chosen (for ex. 7 V AC and 1 MHz). Finally, using Dynamic Light Scattering, an average size of nanoparticles ranging from 5 to 50 nm for pre-diluted TiOCl2 with 16.7% vol. DMFwas obtained depending on flow rates, ageing of samples and implementation or not of an AC electric field
47
Russell, Mary Grace. "Invention and implementation of technologies for continuous flow synthesis." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/127715.
Full textAbstract:
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Chemistry, May, 2019Cataloged from the PDF of thesis.
Includes bibliographical references.
In this thesis, I have optimized a synthesis of rufinamide an important epilepsy medication. This convergent synthesis generates two reactive intermediates in situ (aryl azide and propiolamide) and then combines them in a regioselective click reaction utilizing copper tubing as the catalyst. Next, I have optimized a synthesis of nicardipine which is prescribed to treat high blood pressure. The nature of the project required that the final product be relatively pure (>90 %) so that the final product could be crystallized from the reaction mixture. Nicardipine was synthesized in three steps, but in two flow reactors where one of the reactors induced two steps. The reaction mixture was then purified using two in-line aqueous extrations. First, the reaction stream was washed with HCl to produce the salt of nicardipine and wash away polar compounds. Then, the product is extracted into the aqueous layer by using a 1:1 water DMSO mixture.
Finally, the synthesis's scale was increased and run in the system that was created in collaboration with the Jensen lab and Myerson lab. Next, a fully continuous synthesis of linezolid was optimized and run. The synthesis targeted the challenging intermediate amide epoxide that rapidly cyclizes into unwanted oxazolines. We were able to circumvent this side reactivity by masking the nucleophilic amide N-H by quenching the resulting nitrillium after Ritter type reaction with 2-propanol to produce the imidate. After accessing the masked amide epoxide, linezolid was produced by nucleophilic addition to the epoxide with the aniline made from a nucleophilic aromatic substitution (SNAr) reduction sequence. Finally, late stage oxazolidinone formation produces linezolid in a 73% yield in 27 minutes longest linear sequence. Next, I contributed to a system that automatically optimized and analyzed organic reactions in continuous flow.
This system in collaboration with the Jensen lab fully integrated software, hardware that controlled the continuous platform, and in-line analytics. This system, after the chemist had provided the desired chemical space, could optimize a reaction without any manual intervention. Finally, I developed a monolithic cellular solid made of functionalized silica for catalyst support. This system could solve some of the problems associated with packed bed reactors including catalyst deactivation due to channeling or clogging of the reactor. This type of catalyst support could be applicable to a large number of catalysts by attaching the catalyst to silane side chains with appended functionality. Portions of this thesis have been published in the following articles co-written by the author and have been reprinted and/or adapted with permission from their respective publishers.Zhang, P.; Russell, M.G.; Jamison, T.F. "Continuous Flow Total Synthesis of Rufinamide" Org. Proc. Res. Dev.
2014, 15671570. © 2014 American Chemical Society. MGR ran the optimization of the synthesis as well as isolation and characterization of the final product. PZ wrote the manuscript and validated the results under TFJ's guidance. Zhang, P.; Weeranoppanant, N.; Thomas, D. A.; Tahara, K.; Stelzer, T.; Russell, M. G.; OMahony, M.; Myerson, A. S.; Lin, H.; Kelly, L. P.; Jensen, K. F.; Jamison, T. F.; Dai, C.; Cui, Y.; Briggs, N.; Beingessner, R. L.; Adamo, A. Advaced Continuous Flow Platform for On-Demand Pharmaceutical Manufacturing, Chem. Eur. J. 2018, 24, 2776-2784. DOI: 10.1002/chem.201706004. © 2018 John Wiley & Sons, Inc. MGR optimized the synthesis of nicardipine as well as ran the synthesis in the synthesis frame. PZ, HL, LPK, CD, RLB all woked to develop chemistry for the syntheses of the different drug targets. NW, DAT, and AA worked to develop the up-steam synthesis unit as well as necessary undeveloped components.
KT, TS, MM, YC, and NB woked to deleop the continuous recrystalization unit and purified the drug targets. TFJ, KFJ, and ASM provided instrumental guidance to the teams. Russell, M. G.; Jamison, T. F. "Seven-Step Continuous Flow Synthesis of Linezolid Without Intermediate Purification," Angew. Chem Int. Ed. 2019, 58, 7678-7681. DOI: 10.1002/anie.201901814. © 2019 John Wiley & Sons, Inc. All synthetic work was carried out by MGR under TFJ's guidance. B6dard, A.-C.; Adamo, A.; Aroh, K. C.; Russell, M. G.; Bedermann, A. A.; Torosian, J.; Yue, B.; Jensen, K. F.; Jamison, T. F. Reconfigurable System for Automated Optimization of Diverse Chemical Reactions, Science 2018, 361, 1220-1225. © 2018 American Association for the Advancement of Sciences. Reprinted with permission from AAAS. MGR and ACB worked together to run the various optimizations as well as substrate scopes. AAB developed initial conditions for several of the reactions. AA developed the system with JT and BJ's assistance.
KCA integrated the system with the software as well as modeled the optimization protocols. KFJ and TFJ provided instrumental guidance to the teams. Leibfarth, F. A.; Russell, M. G.; Langley, D. M.; Seo, H.; Kelly, L. P.; Carney, D. W.; Sello, J. K.; Jamison, T. F. Continuous-Flow Chemistry in Undergraduate Education: Sustainable Conversion of Reclaimed Vegetable Oil into Biodiesel, J. Chem. Ed. 2018, 95, 1371-1375. DOI: 10.1021/acs.jchemed.7b00719. © 2018 American Chemical Society. MGR and DML developed and optimized the chemistry. FAL wrote the manuscript and the laboratory experiment. MGR, HS, and LPK, taught the experiment. DWC provided assistance. JKS and TFJ provided guidance.
by Mary Grace Russell.
Ph. D.
Ph.D. Massachusetts Institute of Technology, Department of Chemistry
48
Yang, Haur-Horng. "Flow field analysis of batch and continuous mixing equipment." Case Western Reserve University School of Graduate Studies / OhioLINK, 1993. http://rave.ohiolink.edu/etdc/view?acc_num=case1056640764.
Full text
49
McIlvenna, David. "Raman activated cell sorting and counting in continuous flow." Thesis, University of Glasgow, 2015. http://theses.gla.ac.uk/6333/.
Full textAbstract:
Bacteria play a key role in the natural maintenance of our ecosystem and are also used extensively in agriculture, environmental engineering and in the manufacturing of food products and medicines. However, it is estimated that up to 99% of all micro- organisms are currently unculturable. As a result, it is likely that a vast range of potentially useful phenotypes remain unknown. Current techniques to investigate unculturable cells, such as metagenomics, lack the ability to link a specific piece of genetic information to an originating cell. As heterogeneity of phenotypes exists in populations of genetically identical bacteria, single cell studies are becoming more popular to characterize individual microorganisms. In this thesis a continuous flow, Raman activated single cell sorting system has been developed for the first time. Single cell Raman spectroscopy provides the biochemical information of a cell, enabling the label-free and non-destructive characterisation of different cell types and physiological and phenotypic changes to living cells. The system was based on a novel microfluidic pressure divider platform, where the effects of pressure fluctuations upon the cell detection region are minimised, thereby allowing mechanical switching. With this integrated platform, sorting carbon fixing Synechocystis sp. PCC6803 bacteria containing 12C and 13C isotopes at over 96% accuracy was successfully achieved. Also presented in this thesis is a novel technique for Raman based cell counting in continuous flow. By characterising the likely errors resulting from weak Raman signals, the algorithm used allows accurate analysis of the proportions of known cell types in a mixture, at the fastest acquisition rates achievable on the Raman spectrometer used. The results, obtained in real-time, had an r2 correlation value of 0.996 to the independently measured input proportions. The control of cells at low flow rates offered by the pressure divider microfluidic platform would allow significant increases in Raman signal integration times. The combination of the algorithm with this microfluidic platform could allow real-time Raman based sample analysis and diagnostics to be realised.
50
Wang, Yantao. "Synthesis and conversion of furfural-batch versus continuous flow." Thesis, Compiègne, 2019. http://www.theses.fr/2019COMP2474/document.
Full textAbstract:
Le furfural, identifié comme l'un des 30 principaux produits chimiques biologiques, est une molécule importante en terme de chimie verte et développement durable. L'objectif de ce travail de doctorat est de réaliser la synthèse et la conversion du furfural en flux continu et par lots. Ici, nous avons développé des méthodes plus éco-efficiente pour la synthèse du furfural, et valorisé le furfural en produits à haute valeur ajoutée, tels que le 2-furonitrile, l'alcool furfurylique, etc... Plusieurs questions clés ont été identifiées afin de concevoir des processus plus écologiques que les processus actuels. En détail, des expériences de synthèse du furfural ont été réalisées dans l'eau pure ou dans un mélange eau-solvants organiques lorsque des co-solvants (verts ou écologiques) sont nécessaires. L'irradiation par micro-ondes a été choisie comme méthode de chauffage pour accélérer le processus de déshydratation, et un réacteur à flux continu à micro-ondes a également été utilisé pour améliorer la productivité du furfural. En partant du furfural pour produire des produits chimiques à haute valeur ajoutée, des réacteurs à flux efficace, tels que Pheonix, H-cube Pro ainsi que des micro-ondes à flux continu avec micro-réacteur, ont également été identifiés comme des alternatives intéressantes pour améliorer la productivité des composés cibles. En conséquence, certains résultats prometteurs ont été obtenus du point de vue de l'industrieFurfural, which has been identified as one of top 30 bio-based chemicals, is an important green platform molecule, The aim of this PhD work is to realize the synthesis and conversion of furfural in batch and continuous flow. Here, we developed sorne greener methods for furfural synthesis, and valorized furfural into high value-added products, such as 2-furonitrile, furfuryl alcohol etc. Several keys issues were identified in order to design processes greener than the current ones. ln detail, experiments for furfural synthesis were performed in water or in water and organic solvent when co-solvents (green or eco-friendly) are necessary. Microwave irradiation has been chosen as the heating method to accelerate the dehydration process, and microwave continuous flow reactor was also applied to improve furfural productivity. When starting from furfural to produce high value-added chemicals, efficient flow reactors, suc as Pheonix, H-cube Pro as well as microwave continuous flow With micro-reactor, were also identified as interesting alternatives to improve the productivities of target compounds. As a result, some promising results were obtained in the viewpoint of industry