Development of an improved falling ball viscometer for high-pressure measurements with supercritical CO₂

International audienceThis study presents the development of an improved technique for viscosity measurements under high pressure. The apparatus is based on the principle of the falling ball viscometer, implemented in a high-pressure autoclave fitted with visualisation windows. The originality here is that the balls fall through a tube open at both ends with a diameter slightly greater than that of the balls, allowing a simplified modelling and numerical simulation. A numerical approach has been used for viscosity determination. Calculations have been made with COMSOL Multiphysics® with the laminar Navier–Stokes model for Newtonian mixtures. It includes the specific hydrodynamic effects without the need for a calibration fluid. However, validation experiments were carried out at atmospheric pressure with dimethylsulfoxide (DMSO) at 298, 308 and 318 K and with cocoa butter at 313 and 353 K, with values of viscosity in the range from 1.4 to 45.4 mPa s. Comparative measurements with literature data have been conducted with cocoa butter saturated with carbon dioxide at 313 and 353 K and for pressures ranging from 0.1 to 25 MPa. At 313 K, viscosity varies from 45.4 mPa s to 3.1 mPa s while at 353 K it varies from 12.4 to 1.9 mPa s. For both isotherms tested, within the range 0–15 MPa, the higher the CO2 dissolution in the cocoa butter, the lower the viscosity. However, this decrease in viscosity is more pronounced at the lowest temperature. Above 15 MPa the CO2 dissolution effect on viscosity becomes insignificant, i.e. within the experimental error, due to a counter effect linked with the high hydrostatic pressure. Furthermore, the limits of use of this method have been determined. This technique is revealed as reliable and can therefore be used with other binary systems

Mise au point de méthodes de caractérisation de binaires en milieu supercritique et modélisation des propriétés physiques et thermodynamiques mesurées

This work is focused on the characterization of physical and thermodynamic properties of CO2-cocoa butter (CB) and CO2-PEG400 saturated mixture. Measurements of density, volumetric expansion, viscosity and CO2 solubility were carried out on CB-rich phase at 313 and 353 K and pressures up to 40 MPa. The experimental techniques have previously been compared and validated with DMSO-CO2 mixture. Density measurements were performed using the vibrating tube technology at pressures ranging from 0.1 to 25 MPa. Experimental values were well correlated with the modified Tait equation. CO2 solubility measurements were coupled to the density ones in the same pressures ranges. At 25 MPa, the solubility of CO2 in CB is 31.4 % and 28 .7 % at 313 and 353 K respectively. Phase behaviour was investigated using a view cell in order to follow the expansion of the CB-rich phase with the rise in pressure. Volumetric expansion up to 47 % was measured and correlated to the CO2 solubility. Phase inversion was observed at 313 K and 40 MPa. Lastly, we developed an innovative falling body viscosimeter for high pressure measurements. Viscosity measurements were carried out up to 25 MPa showing a viscosity reduction up to 90 % upon CO2 dissolution. These results were correlated with two empirical models. A new model here presented, was favourably compared with the Grunberg and Nissan model. All the experimental results are consistent with the available literature data. This work opens new perspectives about the determination of the properties of systems such as polymers-CO2 and fats-CO2, which are essential for supercritical process design such as extraction, crystallization, chromatography and synthesis reaction.Depuis une vingtaine d'années, l'utilisation de la technologie des fluides supercritiques suscite un grand intérêt comme alternative aux techniques conventionnelles pour de nombreuses applications telles que l'extraction, le fractionnement, la génération de particules, la chromatographie et la réaction chimique. Cependant, le développement de ce type de procédés nécessite au préalable de caractériser les propriétés du milieu considéré tel que le comportement thermodynamique des phases du point de vue de leurs compositions à l'équilibre et de leur caractéristiques thermophysiques telles que la viscosité, la densité, la diffusivité et l'expansion volumique. De plus, la connaissance de ces propriétés est essentielle à la compréhension des mécanismes des processus mis en jeu mais malencontreusement insuffisante dans la littérature. C'est dans ce contexte que ces travaux de thèse ont été réalisé et ont permis de développer des techniques de caractérisation de propriétés thermophysiques adaptées à la haute pression telles que la viscosimétrie à chute de bille, la mesure de densité utilisant la technologie du tube vibrant et la mesure de solubilité par analyse gravimétrique. Les investigations ont été uniquement menées sur la phase liquide de systèmes binaires très variés du point de vue de la nature physico-chimique des constituants : CO2-DMSO, CO2-PEG400 et CO2-beurre de cacao. Ce travail de thèse a également été consacré à la modélisation de ces propriétés au moyen d'équations d'état et de modèles empiriques ajustés sur les résultats expérimentaux. Développement d'un dispositif de mesure d'équilibre de phase Liquide-Vapeur Cette technique analytique a été développée pour mener des investigations sous haute pression (jusqu'à 35 MPa) de systèmes binaires composés d'une phase liquide (ou fondu) et d'une phase vapeur. Le dispositif a été validé en comparant les résultats obtenus sur le système DMSO-CO2, avec ceux de la littérature. Cet appareillage permet simultanément de déterminer la densité (au moyen d'un densimètre utilisant la technologie du tube vibrant) et la composition d'une phase, en l'occurrence ici la phase liquide, déterminée par analyse gravimétrique. Cette méthode est basée sur le prélèvement dans une cellule de mesure placée sur une balance de précision. L'échantillon de la phase liquide du système étudié, est prélevé dans des conditions de pression et de températures fixées et maintenues constantes lors de l'opération. La séparation des composés est obtenue après dépressurisation de la cellule et la quantité de CO2 initialement dissoute est ainsi déterminée par différence par rapport à la masse de l'échantillon prélevé. Développement d'un viscosimètre à chute de bille Ce dispositif a été spécifiquement conçu pour effectuer de mesures de viscosité sous pression. L'enceinte contenant le viscosimètre est une grande enceinte cylindrique. Les conditions maximales de pression et de température sont respectivement de 44 MPa et 200 °C. La technique est basée sur l'observation de la chute d'une bille d'aluminium (2 mm de diamètre) dans un tube en verre (2.1 mm de diamètre et 20 cm de longueur) au moyen d'une caméra rapide (30 à 500 images/s) au travers des hublots en saphir de l'enceinte. La vitesse terminale de chute permettant de déduire la viscosité du fluide considéré, est déterminée par analyse d'image des films capturés au moyen d'un outil spécialement conçu sous Matlab®. En première approximation, l'écoulement du fluide dans le tube peut-être considéré de type Poiseuille et laminaire. Un bilan de quantité de mouvement sur le fluide permet d'en déduire une définition simplifiée de la viscosité. Cette estimation de la viscosité permet d'initialiser des calculs CFD réalisés par la méthode des éléments finis sous Comsol® Multiphysics. En outre ces calculs ont permis d'estimer le terme correctif tenant compte de la forme spécifique du champ de vitesse à proximité de la bille

Mise au point de méthodes de caractérisation de binaires en milieu supercritique et modélisation des propriétés physiques et thermodynamiques mesurées

ALBI-ENSTIMAC (810042301) / SudocPARIS-MINES ParisTech (751062310) / SudocSudocFranceF

Synthesis of degradable polyphosphoester copolymers for templating calcium carbonate drug delivery carriers

Degradable acid bearing polyphosphoester (PPE) copolymers were prepared by combination of organocatalyzed ring opening polymerization and click chemistry. Their solution behavior and ability to complex calcium ions were studied as well as their capacity to template CaCO3 particles dedicated to drug delivery

Characterization of melted cocoa butter saturated with supercritical CO2

International audienceIn this study, the measurements of density, solubility and volume expansion were carried out at 313 and 353 K and pressures of 5 to 25 MPa. The cocoa butter (CB) used in this work is manufactured by Gerkens Cacao. The experimental procedures were validated with the SC-CO2/butan-1-ol mixture, for which literature data are available. In a first time, we focused on the density measurements, using the vibrating tube principle and on the solubility measurements of the SC-CO2 in CB using a gravimetric procedure. We compared and discussed the results with literature data for instance with those of Venter et al [1]. who performed density and solubility measurements using two different methods (gravimetric and static analytic methods). Phase composition and density measurements were carried out with a good reproducibility and repeatability. Moreover, the experimental density values were correlated with Tait and modified Tait equations and a model specially developed in this study. These models permitted to fit the experimental densities of pure CB and SC-CO2/saturated CB mixture in a wide range of pressures and temperature

Dispositif medical implantable d’injection locoregionale

La présente invention concerne un dispositif médical implantable (1) d'injection locorégionale dans la lumière d'un vaisseau sanguin ou dans un parenchyme comprenant une puce microfluidique (13) et un capot (14), dans lequel la puce microfluidique (13) comprend au moins un canal microfluidique (121) s'étendant depuis une première face de la puce microfluidique (13) jusqu'à une deuxième face de la puce microfluidique (13), le capot (14) comprend au moins deux micro-aiguilles creuses (11) faisant saillie depuis le capot (14), le capot (14) est fixé sur la deuxième face de la puce microfluidique (13) de sorte que le au moins un canal microfluidique (121) soit en connexion fluide avec les au moins deux micro-aiguilles creuses (11) ; et la longueur des au moins deux micro-aiguilles creuses (11) faisant saillie depuis le capot (14) est configuré de sorte que lorsque le capot (14) est implanté sur la paroi externe d'un vaisseau sanguin ou sur un parenchyme, l'extrémité des au moins deux microaiguilles creuses (11) pénètre la lumière du vaisseau sanguin ou dans le parenchyme

Development of Characterization Techniques of Thermodynamic and Physical Properties Applied to the CO2-DMSO Mixture

International audienceThis work is focused on the development of new characterization techniques of physical and thermodynamic properties. These techniques have been validated using the binary system DMSO-CO2 for which several studies of characterization have been well documented. We focused on the DMSO-rich phase and we carried out measurements of volumetric expansion, density, viscosity and CO2 solubility at 298.15, 308.15 and 313.15 K and pressures up to 9 MPa. The experimental procedures were compared and validated with the available literature data on SC-CO2-DMSO system. We made density and CO2 solubility measurements, using respectively the vibrating tube technology and two static analytical methods. Lastly, we developed an innovative falling body viscosimeter for high pressure measurements. All the measurements made are in good agreement with the already published data in spite of very different experimental techniques. This work is a contribution to the understanding of the DMSO-CO2 binary as it implements new viscosity data. Moreover, it opens new perspectives about the determination of the properties of other systems such as polymers-CO2 and fats-CO2, which are essential for supercritical process design such as extraction, crystallization, chromatography and synthesis reaction

Supercritical Carbon Dioxide Fractionation: Case Study for Ethanol-Water Mixtures

The supercritical CO2 fractionation is a process which aims at separating different chemical compounds from a liquid mixture using a supercritical fluid as solvent. This operation can be conducted continuously in a counter-current column, and the use of supercritical carbon dioxide (SC-CO2) enables us to operate at low temperatures with a safe and selective solvent. Hence, this process could be of relevant interest in many industries, on the first hand, to avoid the use of toxic solvents, and on the other hand, to develop new alternatives for complex separations; providing then answers to current environmental and technical issues that correspond to the major challenges of the future. Despite its potential, this process is still little deployed in industrial lines. Indeed, pressure, temperature, and solvent-to-feed ratio (S/F) are all parameters to be considered and optimized for a given application. Moreover, these parameters cover a vast operating field, where the physico-chemical properties of involved phases, and therefore their influence, are not always known. For instance, liquid-fluid interfacial tension and wettability on the packing may affect both transfer phenomenon and column hydrodynamics but their influence remains poorly studied in SC-CO2 medium [1-3]. As consequence, a study on the SC-CO2 fractionation in counter-current packed column (H = 2 m; ID = 19 mm) of a model mixture composed of ethanol-water mixtures, was carried out by varying the parameters above-mentioned, namely the pressure, the temperature, and the S/F. Then, studied conditions involve two pressures of 10.1 MPa and 15.1 MPa, two temperatures of 313 K and 333 K, and three S/F of 9, 24 and 80; corresponding to usual processing conditions for ethanol-water mixtures using SC-CO2 fractionation. Beyond these supercritical CO2 fractionation experiments, an in-depth study about interface properties was also carried out. Thus, measurements of interfacial tension and contact angle on stainless steel of ethanol-water mixtures in CO2 were performed up to 15.1 MPa at 313 K and 333 K, by pendant drop and sessile drop methods, respectively, using a high-pressure tensiometer coupled with picture analysis softwares (Windrop and ImageJ). In addition, the work of adhesion of these mixtures on stainless-steel in saturated SC-CO2 can be estimated thanks to the Young-Dupré equation. This system is a good case study because well-known from a thermodynamical point of view, as well as available feedback from supercritical fractionation. Finally, coupling supercritical fractionation experiments and interfacial property measurements allows us to initiate links between the latter and the flooding phenomena.As results, this work brings first unpublished data on interfacial properties such as contact angles of ethanol-water mixtures on stainless steels (AISI 316 and 316L) in dense CO2. Reduced interfacial tensions and increased contact angles on stainless steel supports in dense CO2 with raised pressure led to low work of adhesion in high pressure range. Moreover, supercritical fractionation results show various behaviors through the large operating field. Hence, among all studied conditions, stable ones are discussed regarding the potential of the supercritical fractionation for ethanol-water mixture separation; while other conditions, that are not stable, are discussed regarding flooding phenomena. Finally, the results put forward in this work allowed us, i) to introduce a first link between the interfacial properties and the “bubble column flooding” through a new dimensionless number that compares the force of adhesion in saturated SC-CO2 to the net weight within SC-CO2; and ii) to discuss a potential link between the interfacial tension, or even the viscosity of the liquid, and the “entrainment” or the “liquid layer flooding” as perspective

Templating calcium carbonate drug delivery carriers based on polyphosphoester copolymers

The design of drug delivery systems (DDS) often requires biodegradable and biocompatible materials that allow safe retention and controlled release of the drug. In this respect, CaCO3 particles are appropriate drug carriers that have excellent properties such as low density, high specific surface areas and porosity for drugs and proteins encapsulation. Here, hyaluronic acid usually used for templating CaCO3 particles was substituted by a degradable synthetic copolymer based on PPE. The latter is a promising candidate due to its biocompatibility, biodegradability and the low toxicity of its degradation products such as phosphates. We also introduced acid functions on the PPE segment in order to enhance its calcium affinity and ability to tune the morphology of the CaCO3 particles. The butynyl phospholane (BYP) polymerization was initiated from poly(ethylene oxide) PEO-OH by organocatalyzed ring opening polymerization (ROP) [2] followed by UV catalyzed thiol-yne addition of 3-mercaptopropionoic acid onto the alkyne functions. CaCO3 particles were then generated in the presence of the copolymer following a procedure inspired from . Well-defined PPE copolymers bearing pendant alkynyl groups, i.e. PEO-b-PBYP (Ð <1.1), were obtained by organocatalyzed ROP of BYP initiated at 0°C from PEO-OH (Scheme 1). The copolymer was then reacted under UV with 3-mercaptopropionoic acid in order to introduce carboxylic acid functions along the PPE backbone by thiol-yne reaction. NMR analyses confirmed that full functionalization was reached after 2h. The high density of acid moieties in PEO-b-PBYP(COO-)2 is supposed to facilitate the Ca2+ complexation. The solution behavior and self-assembly of PEO-b-PBYP(COO-)2 in water was investigated by DLS with and without Ca+2 at different pH. Finally, stoichiometric amounts of CaCl2 and Na2CO3 were mixed in water containing the PEO-b-PBYP(COO-)2 which strongly influences the size of the CaCO3 particles (~1.5 µm). The acid-bearing PPE-based copolymers were successfully prepared and used as templating agents for the synthesis of CaCO3 particles