Orientador: Milton Mori, Marcos A. d'Avila / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-06T05:47:36Z (GMT). No. of bitstreams: 1 Santos_CelsoMurilodos_M.pdf: 3396606 bytes, checksum: 6f04eb0860468401aa6369dba2b5c839 (MD5) Previous issue date: 2005 / Resumo: Colunas de bolhas são equipamentos de simples operação, mas que apresentam uma fluidodinâmica complexa. Seu funcionamento básico é dado pela injeção de um gás (fase dispersa) na base da coluna em um meio líquido (fase contínua). Elas são empregadas nas mais diversas áreas industriais, como processos de química fina, reações de oxidação, reações de alquilação, síntese de Fischer-Tropsch, tratamento de efluentes, reações de fermentação e produção de proteínas, e mais recentemente, em cultura de células. Neste trabalho foram realizadas simulações tridimensionais do escoamento transiente em coluna de bolhas utilizando o pacote computacional de CFD CFX® 5.7 (ANSYS®). Este pacote utiliza o método dos volumes finitos para solucionar as equações governantes de transporte em escoamento multifásico, utilizando a abordagem Euleriana-Euleriana, que mostrou-se adequada para este estudo. Os estudos de casos foram feitos para verificar a influência das propriedades da fase contínua (viscosidade e tensão superficial), da fase dispersa (diâmetro das bolhas) e dos modelos de arraste ... Observação: O resumo, na íntegra, poderá ser visualizado no texto completo da tese digital / Abstract: Bubble columns are equipments of simple operation, but presents a complex fluidodynamic. Its basic operation consists of the injection of a gas (disperses phase) in the bottom of the column in a liquid medium (continuous phase). As reactors, they are used in a variety of chemical processes, such as Fischer-Tropsch synthesis, oxidation reactions, alkylation reactions, effluent treatment, fermentation, reactions, protein production, and more recently, in cell cultures. In this work, three-dimensional simulations of the transient flow in bubble columns was performed using the computational package CFD CFX® 5.7 (ANSYS®). This package uses the finite volumes method to solve the governing equations of transport in multiphase flow using the Eulerian-Eulerian approach, which showed to be adequate for this study. The case studies were carried out in order to verify the influence of the properties of the continuous phase (viscosity and superficial tension), the dispersed phase (diameter of the bubbles) and the drag models ... Note: The complete abstract is available with the full electronic digital thesis or dissertations / Mestrado / Desenvolvimento de Processos Químicos / Mestre em Engenharia Química

Les réactions de catalyse hétérogène impliquant un gaz et un liquide sont mises en oeuvre dans des réacteurs à lit fixes. Ces réacteurs peuvent être assimilés à un milieu poreux. La nature complexe de ce milieu rend la compréhension des interactions entre phases difficile, et nécessite une étude exhaustive à l’échelle globale et locale afin d’identifier les paramètres clés de l’hydrodynamique, des transferts de chaleur et de matière. Nous avons donc développé une cellule miniaturisée bidimensionnelle transparente, qui permet l’observation directe des écoulements avec une très bonne résolution spatiale et temporelle. En faisant varier le débit total et le rapport des débits gaz/liquide, nous avons mis en évidence l’apparition des régimes ruisselant et pulsé, observés par ailleurs dans des systèmes tridimensionnels. Grâce à une méthode d’analyse d’image, nous sommes capables de quantifier et cartographier la saturation liquide locale apparente et la morphologie des phases. L’analyse des variances a permis d’étudier les transitions de régimes pour différentes propriétés de la phase liquide. Cette approche a permis de comparer avec la littérature, mais aussi de s’intéresser aux mécanismes de génération et propagation des instabilités lors des transitions. Il a été mis en évidence que l’apparition des instabilités responsables de la déstabilisation du régime ruisselant intervient pour un nombre deWeber liquide fixé, indiquant que le régime pulsé apparait suite à la déstabilisation des interfaces gaz /liquides par les forces inertielles. Enfin, une étude préliminaire des transferts thermiques dans la cellule a été réalisée. La cellule est utilisée pour réaliser la réaction exothermique d’hydrogénation de l’alpha-methylstyrène. Un modèle simple de transferts thermique a été utilisé pour caractériser l’augmentation de température dans la cellule. Bien que cette approche ne permette pas des mesures quantitatives, elle ouvre à la perspective de suivi de transferts thermiques par caméra infra-rouge. / Heterogeneously catalyzed reactions involving a gas and a liquid phase are frequently achieved in fixed bed reactors. These reactors can be described as a porous medium. The complex nature of this medium makes the understanding of the interplay between phases difficult, and requires a thorough study at the global andlocal scale to identify the key parameters of hydrodynamics, mass and heat transfers. Therefore, we have developed a miniaturized two-dimensional system that is transparent to allow the direct observation of the flow with very high spatial and temporal resolution. While varying the total flow rate and the gas/liquid flow rate ratio, we observe the appearance of the trickle and the pulse flow regime, which can be observed in threedimensional beds. Thanks to some image analysis techniques, we are able to quantify and to map the local apparent liquid saturation and the morphology of the phases. Variances analysis allowed the study of the transition for different liquid properties. This approach allowed the comparison with the existing state of art, but also the study of the onset and propagation mechanisms of the instabilities during the transition. We report that the onset of instabilities responsible for the destabilization of the trickle flow regime occurs at a fixed Weber number. This indicates that the pulsed regime is due to the destabilization of the gas/liquid interface by inertial forces. Finally, a preliminary study of thermal transfers in the device was realized. The device was used to perform the exothermic hydrogenation of alpha-methylstyrene. A simple model is used to characterize the temperature increase in the device. Although this approach does not allow quantitative measurements, it opens up the perspective of monitoring thermal transfers with an infra-red camera.

L’évaporation d’une solution solvant/soluté est un processus transitoire qui prend fin lorsque le solvant a totalement disparu. Le refroidissement créé par le changement de phase provoque des gradients à la fois thermiques et de concentration en solvant. Ces homogénéités diffusent ensuite dans l’épaisseur de la solution et sont susceptibles d’engendrer un écoulement fluide. L’origine de cette convection peut être liée à des variations de tension de surface ou de densité. Des travaux expérimentaux ont montré que l’épaisseur des dépôts issus de séchages de solutions solvant/soluté semblait pouvoir être corrélée avec les cellules de convection de la zone fluide. Une compréhension approfondie des phénomènes à l’origine de la convection devrait donc participer à un meilleur contrôle de la qualité des dépôts.Sur la base de travaux numériques et expérimentaux publiés, nous avons étudié l’apparition de la convection pour trois types de modèles représentant le processus d’évaporation d’une solution de Polyisobutylène-Toluène : un modèle purement thermique qui s’applique pour les temps courts, un modèle solutal qui est valable sur les temps longs et enfin un modèle couplé thermique/solutal qui représente les transferts sur l’ensemble de la gamme des temps étudiés. Le caractère transitoire de l’évaporation induit une difficulté pour caractériser la naissance de la convection à partir d’un régime de conduction. En effet, cette convection apparaît à partir d’un germe qui est une petite perturbation de la solution diffusive. Si l’amplitude de cette perturbation est trop faible, son amplification à des intensités suffisantes ne pourra pas avoir lieu avant la fin du régime transitoire et l’écoulement ne deviendra donc jamais convectif. Le rôle de la perturbation est donc primordial. Dans des travaux numériques antérieurs, cette perturbation a été imposée à l’état initial, généralement avec une distribution aléatoire du champ thermique ou de vitesse. Lors de cette thèse, nous avons opté pour un modèle plus physique, basé sur l’introduction d’un transfert thermique sur les parois latérales qui joue le rôle de perturbateur de l’écoulement diffusif transitoire.Dans cette thèse, nous avons établi par voie numérique les seuils de transition entre une solution diffusive et un écoulement convectif pour les modèles thermique, solutal et couplé, dans le cas d’une approximation bidimensionnelle du film liquide et des simulations pleinement tridimensionnelles. Des diagrammes spatio-temporels et l’étude des cellules à la surface libre par des reconstructions de Voronoï nous ont permis de mieux comprendre la naissance et la propagation des instabilités dans la solution fluide / The evaporation of a solvent/solute solution is a transient phenomenon which ends when the whole solvent has disappeared. Phase change generates a cooling of the liquid-gas interface, and consequently, it creates thermal and solutal gradients. These homogeneities spread in the core solution and produce, eventually, a fluid flow. This convection can be due to the surface tension and/or buoyancy variations. Experimental works have shown that some coating thicknesses stemming from drying processes are correlated to the size of the convection cells in the fluid region. A thorough understanding of the physical phenomena responsible to fluid convection should contribute to improve the control of deposit quality.Based on numerical and experimental works, we have studied the onset of convection for three kinds of models for the drying process of a Polyisobutylene-Toluène solution: A pure thermal model which is valid for short times, a solutal model devoted to the simulation of long times, only, and a thermal/solutal coupled model which takes into account the heat and mass transfer over a long time period of the evaporation process. The transient nature of the evaporation problem raises the issue of how to define the onset of the convective flow from a diffusive solution. Indeed, this flow motion occurs from a seed which is a small perturbation of the transient diffusive solution. If the perturbation is too weak, the necessary time interval for a significant growing of its magnitude will be greater than the time scale of the transient regime: thus the solution will never be considered as convective. Consequently, the influence of the perturbation is fundamental. In previous numerical works, this perturbation was imposed at the initial state, often through a random spatial distribution applied to the velocity or temperature field. In the present contribution, we have adopted a physical model where the adiabatic lateral walls have been replaced by diathermal walls: The local thermal inhomogeneities create a very weak flow acting as a small disturbance for the transient diffusive solution.In this thesis, we have developed a numerical model to evaluate the thresholds between the diffusive solutions and the convective flows, for the thermal, solutal and thermal/solutal coupled models, for two- and three-dimensional approximations of the Polyisobutylene-Toluène liquid film. Space-time diagrams and convective cell reconstructions at the liquid-gas interface by a Voronoï algorithm allowed us to get a better understanding of the way the disturbances propagate from the lateral walls for finally giving rise to a convective flow in the core fluid

L’étude et la mise au point des procédés de traitement du biogaz représentent un défi majeur à relever pour accéder à une énergie propre produite à partir d’une unité de méthanisation. Le biogaz est un mélange de CH4 à 55% v/v et de CO2 à 40% v/v. La technique de l’absorption de CO2 par lavage à l’eau sous pression a été choisie dans cette thèse. L’optimisation, le contrôle et l’étude expérimentale de ce procédé, appelé EPUROGAS, ont été réalisés à l’échelle d’une ferme sur un prototype traitant un débit nominal de 40 Nm3/h. Deux axes de recherche ont été privilégié dans la mise au point de l’EPUROGAS : l’entraînement de méthane par l’eau et le recyclage de l’eau sans stripping pour permettre une valorisation simultanée du CH4 et du CO2 produits. Les principales innovations de ces travaux sont protégées par deux brevets : l’amélioration de la base de la colonne d’absorption et une méthode originale de désorption par mélangeur statique. Lors de ces travaux, une méthode statistique d’analyse des résultats expérimentaux a été proposée. Deux modèles prédictifs de génie des procédés ont été élaborés afin de prédire l’efficacité d’absorption du CO2 et le rendement de production de CH4. Un pilote complémentaire a été étudié : le SATUROMETRIX qui permet de caractériser des équilibres gaz/liquide entre plusieurs gaz et un liquide complexe sous pression, complétant les données bibliographiques des constantes de Henry associées aux mélanges complexes. Enfin, un système PSA qui conditionne le biogaz ou le méthane pré-épuré en Gaz Naturel Véhicule comprimé à 200 bar a été étudié. Les procédés EPUROGAS et PSA ont été couplés, évalués énergétiquement puis dans leur globalité par l’Analyse de Cycle de Vie. / Biogas upgrading is a key technology for the renewable energy mix of tomorrow. Biogas is a mix of Carbon Dioxide (40%) and Methane (55%). It is obtained thanks to the anaerobic digestion of organic matter. The adapted High Pressure Water Scrubbing process was studied in this thesis. The process was installed in farm and operated at a real scale for upgrading biogas flows up to 40 Nm3/h. It is called EPUROGAS. Two main research axes were obtained with a preliminary study on a prototype: biogas leaks were detected at the water outlet and stripping water with air allowed both CH4 and CO2 production. Works have led through innovation with two patents: an enlarged column bottom and a static mixer to enhance CO2 desorption from water. During this work, experimental results were collected during operation and statistically studied. Thanks to theoretical studies, two predictive models were built to predict CO2 absorption efficiency and CH4 rate recover. Moreover, two complementary processes were studied. SATUROMETRIX is a laboratory apparatus that aims to characterize gas/liquid equilibrium under pressure for mixed gases and a complex liquid phase. PSA system is an adsorption process for biogas upgrading operating with biogas or half upgraded biogas. It leads to Compressed Natural Gas at 200 bars. Finally, EPUROGAS and PSA were coupled in order to conduct their energetic study and their Life Cycle Analysis

Cette thèse se focalise sur les écoulements gaz-liquide dans un milieu poreux, problématique rencontrée dans des domaines variés allant de la physique fondamentale à la chimie appliquée. Nous avons caractérisé expérimentalement les régimes hydrodynamiques dans deux géométries différentes : un canal millifluidique (écoulement quasi-1D) et une cellule de Hele-Shaw (écoulement quasi-2D). L’originalité de ce travail est d’analyser l’effet du milieu poreux (lits de billes polydisperses ou mousses solides à cellules ouvertes), du confinement (1D/2D) et de la gravité en couplant des approches locales et globales développées dans les communautés de physique expérimentale et de génie chimique. D’une part, une analyse globale a permis de quantifier les pertes de charge [1] et, basée sur le transport d’un traceur fluorescent, les distributions de temps de séjour [2] et le transfert gaz-liquide dans l’expérience 1D ; d’autre part, une analyse locale de la fraction liquide et l’évolution spatio-temporelle de son contenu fréquentiel ont permis de mettre en évidence deux régimes hydrodynamiques dans le canal millifluidique [3-5] : un régime pseudo-Taylor, où les caractéristiques de l’écoulement périodique amont sont conservées, et un régime modulé, pour lequel l’écoulement se désorganise à l’entrée du milieu poreux. Un modèle phénoménologique basé sur la propagation des bulles dans le milieu est proposé, et rend compte de l’existence de ces deux régimes [4,5]. Enfin, ces deux analyses sont couplées pour étudier les écoulements dans la cellule de Hele-Shaw, et une analyse dimensionnelle de l’effet du confinement et de la gravité sur les écoulements gaz-liquide dans un milieu poreux est proposée.Références –[1] M. Serres, R. Philippe & V. Vidal, to be submitted to Geophys. Res. Lett. (2017). [2] M. Serres, D. Schweich, R. Philippe & V. Vidal, to be submitted to Chem. Eng. Sci. (2017).[3] M. Serres, R. Philippe & V. Vidal, Compte-rendus de la 19e Rencontre du Non-Linéaire, Eds. E. Falcon, M. Lefranc, F. Pétrélis & C.-T. Pham, Non-Linéaire Publications, 109-114 (2016).[4] M. Serres, M.-L. Zanota, R. Philippe & V. Vidal, Int. J. Multiphase Flow 85, 157-163 (2016).[5] M. Serres, T. Maison, R. Philippe & V. Vidal, to be submitted to Int. J. Multiphase Flow (2017). / This thesis focuses on gas-liquid flow in porous media, a common problem encountered in various domains from fundamental physics to applied chemical engineering. We have characterized the hydrodynamic regimes based on two different experimental devices geometry: a millichannel (1D flow) and a Hele-Shaw cell (2D flow). The originality of this work is to analyze the influence of the porous medium (monodisperse micro-packed beds or open cell solid foams), confinement (1D/2D) and gravity by coupling global and local analysis from either chemical engineering or fundamental physics community. On the one hand, a global analysis made it possible to quantify pressure drops, residence time distributions (RTD) based on fluorescent dye transport and gas-liquid mass transfer on the 1D device. On the other hand, a local analysis of the liquid fraction and the spatio-temporal evolution of its frequency pointed out the existence of two hydrodynamic regimes: a Taylor-like regime in which the characteristics of the periodic flow upstream are conserved in the porous medium and a modulated regime characterized by the flow disorganization at the porous medium entrance. A phenomenological model is developed based on bubbles propagation inside the medium and reproduces well both regimes. These two analyses are finally coupled to study multiphase flows inside the Hele-Shaw cell. The effects of gravity and confinement are discussed.

Gas-liquid two-phase flows occur in many industrial applications and apparatuses. The design and optimization of such apparatuses and processes requires the numerical simulation of two-phase flows. However, two-phase flow simulations are still a challenging task, especially for industrial scales. Here, the simulation of large flow domains and high Reynolds number flows require a reduction of the resolved time-scales and length-scales by a high level of modeling to decrease the computational effort. Therefore, physics-based models are needed to depict the complex transport processes between the phases. Thus, two-phase flows are the object of ongoing research. Up to now, the majority of closure models for turbulence, interfacial forces or bubble breakup and coalescence were validated against experimental data derived from experiments in simple flow channel geometries like straight pipes. Their application for the simulation of two-phase flows with three-dimensional flow structures like e.g. recirculating areas, flow separation or strong velocity gradients requires constant experimental validation and further development. Hence, improved experimental methods are required for investigations of gas-liquid two-phase flows to provide reliable data for further development and validation of numerical flow simulation models. Therefore, experiments were performed in a constricted pipe under bubbly two-phase flow conditions. Three-dimensional flow structures were created by two types of flow constrictions for a variety of gas and liquid superficial velocities up to jg = 0.1400 m⋅s-1 and jl = 1.6110 m⋅s-1. The flow fields upstream and downstream of the flow constrictions were studied using ultrafast X-ray tomography and hot-film anemometry to obtain cross-sectional phase distribution, bubble characteristics and liquid velocity. The analysis of the ultrafast X-ray tomography image data was significantly improved by development of a histogram-based gas holdup calculation. Furthermore, the spatial dependence of the axial image plane distance was studied to improve the determination of axial bubble velocities and, thus, bubble sizes. The experimental method was advanced by simultaneous application of ultrafast X-ray tomography and hot-film anemometry. Eventually, the experimental data was compared to state-of-the-art Euler/Euler two-fluid simulations. The simulations were performed in the framework of a parallel doctoral thesis in the Experimental Thermal Fluid Dynamics department at the Helmholtz-Zentrum Dresden – Rossendorf by Ms. Sibel Tas-Koehler following the baseline approach. The results were compared in terms of the phase distribution, bubble sizes and gas velocity for two operating conditions using the homogeneous multiple size group model. / Zweiphasenströmungen aus Gasen und Flüssigkeiten treten in vielen industriellen Anwendungen und Apparaten auf. Um einen sicheren, zuverlässigen und optimalen Betrieb einzelner Komponenten und gesamter Anlagen zu gewährleisten, sind die Strömungen Gegenstand zahlreicher Untersuchungen. Numerische Simulationen sind ein unverzichtbares Instrument, um Prozesse unter diesen Aspekten zu bewerten. Die Simulation von Zweiphasenströmungen, insbesondere im industriellen Maßstab, ist jedoch nach wie vor eine anspruchsvolle Aufgabe. Um den Rechenaufwand zu verringern und die Simulation von großen Strömungsgebieten und Strömungen mit hohen Reynoldszahlen zu ermöglichen, ist ein hohes Maß an Modellierung notwendig. Gleichzeitig wurden die meisten Schließungsmodelle zur Beschreibung von Turbulenz, Grenzflächenkräften oder Blasenzerfall und -koaleszenz für einfache Geometrien wie beispielsweise gerade Rohre entwickelt. Die Anwendung dieser Modelle für die Simulation von Zweiphasenströmungen mit dreidimensionalen Strömungsstrukturen, wie z.B. Rezirkulationsgebieten, Strömungsablösungen oder starken Geschwindigkeitsgradienten, erfordert eine ständige experimentelle Validierung und Weiterentwicklung. Dies wiederum erfordert eine immer höhere Auflösung der eingesetzten Messsysteme und steigende Qualität der experimentellen Daten. Um verlässliche Daten für die Weiterentwicklung und Validierung von Modellen für die numerische Strömungssimulation zu erhalten sind daher verbesserte experimentelle Methoden zur Untersuchung von Gas-Flüssig-Strömungen erforderlich. Aus diesem Grund wurden Experimente an einer Blasenströmung in einem Rohr mit einer Strömungsverengung durchgeführt. Zwei Arten von Verengungen wurden genutzt, um dreidimensionale Strömungsstrukturen für eine Vielzahl von Betriebsbedingungen zu erzeugen. Diese sind durch Gas- und Flüssigkeitsleerrohrgeschwindigkeiten bis zu jg = 0.1400 m⋅s-1 und jl = 1.6110 m⋅s-1 definiert. Um die Phasenverteilung im Querschnitt der Strömung, Blaseneigenschaften und die Flüssigphasengeschwindigkeit stromauf- und -abwärts der Verengung zu ermittelt, wurde die Strömung mit Hilfe der ultraschnellen Röntgentomographie und Heißfilm-Anemometrie untersucht. Die Datenanalyse für die Bilddaten der ultraschnellen Röntgentomographie wurde durch die Entwicklung einer Histogramm-basierten Gasgehaltsberechnung erheblich verbessert. Um die Bestimmung der axialen Blasengeschwindigkeiten und damit der Blasengrößen zu verbessern, wurde außerdem die räumliche Abhängigkeit des axialen Bildebenenabstands untersucht. Die experimentellen Methoden wurden durch die gleichzeitige Anwendung von ultraschneller Röntgentomographie und Heißfilm-Anemometrie weiterentwickelt. Die experimentellen Daten wurden mit dem Stand der Technik von Euler/Euler-Zweiphasen-Simulationen verglichen. Die Simulationen wurden im Rahmen eines parallelen Promotionsvorhabens in der Abteilung Experimentelle Thermofluiddynamik am Helmholtz-Zentrum Dresden – Rossendorf von Frau Sibel Tas-Köhler durchgeführt und folgten der Baseline-Modell Strategie. Die Ergebnisse wurden unter Verwendung des homogenen Modells mehrerer Größenklassen bezüglich der Phasenverteilung, der Blasengrößen und der Gasgeschwindigkeit für zwei Betriebsbedingungen verglichen.

An experimental investigation has been carried out to study the heat transfer in a two-phase two-component mixture flowing upward inside a 1" double pipe heat exchanger. The heat transfer coefficient was measured using either air to lift the liquid (air-lift system) or a mechanical pump. The heat transfer coefficient results have been extensively studied and compared with other workers' results. An attempt was made to correlate the present heat transfer data in dimensionless correlations. Possible factors affecting the two-phase heat transfer coefficient have been studied with special attention being given to the fluid properties, particularly the liquid viscosity. Experiments were also carried out to investigate the effect of solid particles added to a liquid flow on the measured heat transfer coefficient. The present investigation was carried out using air as the gas-phase ranging from 2x 10-5 up to 80 x 10-5 m3/s. Liquids used were water and glycerol solutions with viscosity ranging from 0.75 up to 5.0 C. P. and flowrates between 4x 10-5 and 25 x 10-5 m3/s. Void fraction and pressure drop were also measured during the heat transfer process. Flow pattern in gas-liquid mixture was investigated in a perspex tube of identical dimensions to the heat exchanger tube.

Due to the ever increasing concerns about pollutants and contaminants found in water, new treatment technologies have been developed. Ozonation is one of such technologies. It has been widely applied in the treatment of pollutants in water and wastewater treatment processes. Ozone has many applications such as oxidation of organic components, mineral matter, inactivation of viruses, cysts, bacteria, removal of trace pollutants like pesticides and solvents, and removal of tastes and odours. Ozone is the strongest conventional oxidant that can result in complete mineralisation of the organic pollutants to carbon dioxide and water. Because ozone is unstable, it is generally produced onsite in gas mixtures and is immediately introduced to water using gas/liquid type reactors (e.g. bubble columns). The ozone reactions are hence of the type gas liquid reactions, which are complex to model since they involve both chemical reactions, which occur in the liquid phase, and mass transfer from the gas to the liquid phase. This study focuses on two aspects: mass transfer and chemical reactions in multicomponent systems. The mass transfer parameters were determined by experiments under different conditions and the chemical reactions were studied using single component and multicomponent systems. Two models obtained from the literature were adapted to the systems used in this study. Mass transfer parameters in the semi-batch reactor were determined using oxygen and ozone at different flow rates in the presence and absence of t-butanol. t-Butanol is used as a radical scavenger in ozonation studies and it has been found to affect the gas¿liquid mass transfer rates. An experimental study was carried out to investigate the effects of t-butanol concentrations on the physical properties of aqueous solutions, including surface tension and viscosity. It was found that t-butanol reduced both properties by 4% for surface tension and by a surprising 30% for viscosity. These reductions in the solution physical properties were correlated to enhancement in the mass transfer coefficient, kL. The mass transfer coefficient increased by about 60% for oxygen and by almost 50% for ozone. The hydrodynamic behaviour of the system used in this work was characterised by a homogeneous bubbling regime. It was also found that the gas holdup was significantly enhanced by the addition of t-butanol. Moreover, the addition of t-butanol was found to significantly reduce the size of gas bubbles, leading to enhancement in the volumetric mass transfer coefficient, kLa. The multicomponent ozonation was studied with two systems, slow reactions when alcohols were used and fast reactions when endocrine disrupting compounds were used. ii These experiments were simulated by mathematical models. The alcohols were selected depending on their volatilization at different initial concentrations and different gas flow rates. The degradation of n-propanol as a single compound was studied at the lowest flow rate of 200 mL/min. It was found that the degradation of n-propanol reached almost 60% within 4 hours. The degradation of the mixture was enhanced with an increase in the number of components in the mixture. It was found that the degradation of the mixture as three compounds reached almost 80% within four hours while the mixture as two compounds reached almost 70%. The effect of pH was studied and it was found that an increase in pH showed slight increase in the reaction. Fast reactions were also investigated by reacting endocrine disrupting chemicals with ozone. The ozone reactions with the endocrine disrupters were studied at different gas flow rates, initial concentrations, ozone concentrations and pH. The degradation of 17¿-estradiol (E2) as a single compound was the fastest, reaching about 90% removal in almost 5 minutes. However estrone (E1) degradation was the lowest reaching about 70% removal at the same time. The degradation of mixtures of the endocrine disruptors was found to proceed to lower percentages than individual components under the same conditions. During the multicomponent ozonation of the endocrine disruptors, it was found that 17¿-estradiol (E2) converted to estrone (E1) at the beginning of the reaction. A MATLAB code was developed to predict the ozone water reactions for single component and multicomponent systems. Two models were used to simulate the experimental results for single component and multicomponent systems. In the case of single component system, good simulation of both reactions (slow and fast) by model 1 was obtained. However, model 2 gave good agreement with experimental results only in the case of fast reactions. In addition, model 1 was applied for multicomponent reactions (both cases of slow and fast reaction). In the multicomponent reactions by model 1, good agreement with the experimental results was also obtained for both cases of slow and fast reactions. / Ministry of Higher Education in Libya and the Libyan Cultural Centre and Educational Bureau in London.

Данная работа предполагает разработку методики анализа остаточных органических растворителей (ООР) в субстанциях натрия 3,8-диэтоксикарбонил-4-оксо-4Н-пиразоло[5,1-c][1,2,4]триазинид моногидрата (AB-19) и натрия 7-метилтио-4-оксо-3-циано-4Н-[1,2,4]триазоло[5,1-c][1,2,4]триазинида тригидрата (MNR-857). Анализ литературных данных показал, что наиболее предпочтительным методом определения ООР является метод газожидкостной хроматографии с парофазным вводом пробы. Для определения целевых аналитов в исследуемых субстанциях рассмотрены схемы синтеза и строение соединений, и определено, что образцы могут содержать органические растворители II (гексан, пиридин, метанол) и III (этанол, этилацетат, 2-пропанол) классов опасности. Однако опытные данные показали наличие в образцах субстанций только этанола и пропан-2-ола. В связи с этим проводили количественное определение только указанных растворителей. На основе литературных данных были определены исходные условия проведения хроматографического анализа. На практике исходная методика была скорректирована: изменение массы навески, разведения образца, времени выдерживания виалы, установление диапазона концентраций применения методики и метода количественного определения. Разработанную методику анализа подвергали испытаниям на пригодность по таким показателям как специфичность, линейность, предел количественного определения, сходимость, промежуточная прецизионность и правильность. Согласно проведенным исследованиям была доказана достоверность и надежность получаемых с использованием данной методики результатов. Количественное определение ООР с помощью разработанной методики в образцах субстанций AB-19 (3 партии синтеза) и MNR-857 (5 партий синтеза) подтвердило их соответствие требованиям ОФС.1.1.0008.15 по показателю остаточные органические растворители (не более 0,5 % для растворителей III класса опасности). / This paper discusses the development of a method for assay of residual organic solvents in substances in substances such as sodium 3,8-diethoxycarbonyl-4-oxo-4H-pyrazolo[5,1-c][1,2,4]triazinide monohydrate (AB-19) and sodium 7-methylthio-4-oxo-3-cyano-4H-[1,2,4]triazolo[5,1-c][1,2,4]triazinide trihydrate (MNR-857). An analysis of the literature data showed that the most preferred method for determining residual organic solvents is headspace gas-liquid chromatography. To determine the target analytes in the studied substances, synthesis schemes and the structure of compounds are considered. Thanks to this, it was decided that the samples might contain organic solvents of hazard classes II and III. Class II includes hexane, pyridine, methanol, and сlass III includes ethanol, ethyl acetate, 2-propanol. However, experimental data showed the presence of only ethanol and propan-2-ol in the samples of substances. In this regard, an assay was carried out only for these two solvents. Based on literature data, the initial conditions for the chromatographic analysis were determined. The original method was adjusted by changing the test portion of sample, diluting the samples, the holdup time of the vial, as well as by establishing ranges of concentrations and the method of quantitative measurement. The developed analysis method was tested for suitability by such indicators as specificity, linearity, limit of quantification, repeatability, intermediate precision, and accuracy. According to the research, it was demonstrated that the analytical technique is acceptable for solving the task. The residual organic solvents were quantified using the developed procedure for three batches of synthesis of substance AB-19 and for five batches of synthesis of substance MNR-857. The percentage of residual organic solvents in all samples was less than 0.5%. Thus, the results obtained satisfy the requirements of the article OFS.1.1.0008.15 of the State Pharmacopoeia of the Russian Federation in terms of residual organic solvents.

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