Production of uniform O/W emulsions through a porous medium of micron-sized glass beads (original) (raw)
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JOURNAL OF CHEMICAL ENGINEERING OF JAPAN
A novel method of emulsion preparation by intramembrane premix membrane emulsi cation without preliminary emulsi cation was developed for the preparation of monodispersed oil-in-water (O/W) and water-in-oil-in-water (W/O/W) emulsions with small droplet size and high disperse phase content at high productivity. The dispersed phase and the continuous phases were simultaneously permeated through Shirasu Porous Glass (SPG) membranes with mean pore sizes of 5, 10, and 20 µm at a membrane permeation rate over 50 m 3 /m 2 h. Monodispersed emulsions with disperse phase content of 25 to 95% by volume, mean droplet size to the mean pore size ratio of 1.2 to 0.26, and with droplet size distribution (span) of 0.4 to 0.6 were prepared. The emulsion droplet size decreased with membrane permeation rate, continuous phase viscosity and the number of membrane permeation cycles. A composite W/O/W emulsion with an average droplet size of 10.4 µm, a span of 0.5 and of disperse phase content of 50% by volume was also prepared in a sequence of consecutive steps without integrating the preliminary emulsi cation step by high-shear homogenization.
Journal of Membrane Science, 2004
Multiple W/O/W emulsions have been prepared by multi-stage (repeated) premix membrane emulsification using Shirasu-porous-glass (SPG) membrane with a mean pore size of 10.7 µm. A coarse emulsion containing droplets with a mean particle size of about 100 µm was homogenized 5-6 times through the same membrane at a constant pressure difference of 20-300 kPa to achieve additional droplet homogenization and size reduction. The optimum conditions with regard to particle size uniformity were 3 homogenization cycles at a pressure difference of 100 kPa, under which the mean size of outer W/O particles was 9 µm and the span of particle size distribution was as low as 0.28. The optimum pressure difference in a single-stage process was higher, but the-2particle size distribution of prepared emulsions was broader than in a multi-stage process at smaller pressures. The transmembrane flux was in the range of 1.8-37 m 3 /(m 2 h) and increased with increasing pressure difference and decreasing the content of W/O particles. The mean size of W/O particles in each cycle was remarkably constant over a wide range of their concentration of 1-60 vol. %.
Influence of the emulsion formulation in premix emulsification using packed beds
Chemical Engineering Science, 2014
ABSTRACT Premix emulsification was investigated using packed beds consisting of micron-sized glass beads, a system that avoids fouling issues, unlike traditional premix membrane emulsification. The effects of emulsion formulation were investigated, most notably the viscosity and the surfactant. The droplet size was reduced by increased shear stress in the emulsion. This was stronger at low viscosity ratios than at high ratios. As expected the flux was proportional to the overall emulsion viscosity, and emulsions with small droplet size (Sauter mean droplet diameter <5 μm) could still be produced at up to 60% of dispersed phase provided that sufficient surfactant was available. More uniform emulsions (span≈0.75) were produced with Tween-20 (nonionic) and SDS (anionic) as surfactants than with CTAB (a cationic surfactant), possibly due to a combination of a low equilibrium interfacial tension and electrostatic attractions with the glass surface. Scaling relations were proposed taking into account all investigated product properties that can describe the droplet size successfully.
Manufacture of controlled emulsions and particulates using membrane emulsification
2008
Crossflow and rotating membrane emulsification techniques were used for making oil-in-water (O/W) emulsions. The emulsions produced from a variety of oils and monomers (viscosity 7-528 mPas) exhibited narrow size distributions over a wide droplet size range, with the average droplet size ranging from less than 1 µm up to 500 µm. The monomer emulsions were further encapsulated to produce microcapsules through subsequent polymerisation reactions. The monodispersity feature of the primary emulsions was retained after the encapsulation. In comparison with other homogenisation methods, our experimental results demonstrated that the membrane emulsification technique is not only superior in emulsion droplet size controls, but also advantageous in energy efficiency and industrial-scale productions.
Food emulsions using membrane emulsification: conditions for producing small droplets
Journal of Food Engineering, 1999
Ceramic membranes were used to produce oil-in-water (O/W) emulsions consisting of vegetable oil as the dispersed phase and skim milk as the dispersion medium. The purpose of the work was to ®nd operating conditions suitable for producing small emulsion droplets, a small size being important for emulsion stability. The main parameters investigated were the eect of wall shear stress, emulsi®er concentration and membrane pore size. Formation of small droplets was favoured at higher emulsi®er concentrations and for a high wall shear stress using a membrane with a small nominal pore size. Submicron particles were produced at an 8% emulsi®er concentration for a wall shear stress of 135 Pa using a 0.1 lm pore size membrane. Under these conditions the¯ux was >100 kg m À2 h À1 . A high¯ux is important for industrial-scale production of food emulsions using membrane emulsi®cation. Ó
Droplet break-up mechanism in premix emulsification using packed beds
Chemical Engineering Science, 2013
c Oil-in-water emulsions were successfully prepared using packed beds. c Interstitial void size and flow velocity determined the droplet break-up. c Droplet break-up either dominated by constriction (Re o 40) or inertia (Re 4 40). a b s t r a c t Some emulsification techniques based on microstructures are known for the monodispersity of produced droplets, however, they lack in scalability. The techniques that are able to produce emulsions in larger amounts do not usually produce monodispersed droplets. We here report on a specific technique that has the potential to combine the best of both worlds: premix emulsification using a packed bed of differently sized glass beads (55, 65, 78 and 90 mm) supported by a metal sieve. The production of oil-in-water emulsions was targeted, and the process conditions especially related to internal structure of the porous media like interstitial void size and bed height were investigated.
Journal of Membrane Science, 2014
Membrane emulsification is a promising technology for the production of micro-nano particles, which is able to compete with the conventional mechanical emulsification processes. The production of emulsions with narrow droplet size distribution at dispersed phase fluxes (productivity) sufficiently high to make the process suitable for industrial application is still a considerable challenge. The interfacial tension between the dispersed phase and the membrane pore wall is a crucial parameter to maintain droplets shape while enhancing productivity. In the present paper, a membrane thickness with asymmetric properties in terms of wettability between external and internal sides has been tested in the preparation of W/O emulsions. The membrane surface wettability modification was obtained by adsorption of hydrophobic macromolecules on the lumen side of hydrophilic membrane. Lipase was used as a model macromolecule. W/O emulsion droplets with smaller droplets size have been produced with lipaseloaded membrane compared with the unmodified hydrophilic membrane. High dispersed phase flux of 30 L h À 1 m À 2 was also obtained with a significant increase of process productivity compared to the use of hydrophobic membranes. These results show that membrane-protein interaction can be used to functionalize opportunely the membrane for membrane emulsification application reducing emulsification time and increasing dispersed phase flux without modifying the control on droplets properties in terms of size and size distribution.
High throughput production of double emulsions using packed bed premix emulsification
Food Research International, 2014
ABSTRACT Abstract We explored the potential of packed bed premix emulsification for homogenizing coarse food grade W/O/W emulsions, prepared with sunflower oil. Using packed beds with different glass bead sizes (30–90 μm) at different applied pressures (200–600 kPa), emulsions with reasonably uniform droplet size (span ~ 0.75) were produced successfully at high fluxes (100–800 m3 m− 2 h− 1). Sodium chloride was used as a release marker: after five homogenization cycles, the produced emulsions were found to retain almost all of their initial content (99%). As was previously found for single emulsions, the packed bed system proved to be effective in breaking up the W/O/W emulsion droplets, with droplet to pore size ratios as low as 0.3. Results were analysed through the pore Reynolds number, Rep, which characterizes the flow inside the packed bed, and were related back to the droplet break-up mechanisms occurring. At high Rep, droplet break-up was expected to be governed by shear forces while at low Rep, there is a shift from shear based to spontaneous droplet break-up.
Enhancing the Throughput of Membrane Emulsification Techniques To Manufacture Functional Particles
Industrial & Engineering Chemistry Research, 2009
Formulation technologies increasingly demand the manufacture of droplets with user-controlled size and size distributions for applications in emulsions, capsules, and semisolid particulates. These are used in various functional consumer products. This paper introduces methods to enhance throughput for two types of membrane emulsification system, using cross-flow and rotating membrane technology. Modification of the interaction between the dispersed phase and the surface of the membrane, the inner wall of the pores (through control of hydrophobicity), pore orientation, and pore shape is demonstrated to increase emulsion droplet productivity. Such methods can also be deployed in the production of capsule materials using emulsion precursors. The possible mechanisms underlying the enhancements are discussed. It is concluded that noncircular pores can offer significant process benefits for the production of uniform droplets and semisolid particulates. It is demonstrated that the droplet formation rate can be doubled through optimization of the orientation of noncircular pores in a rotating membrane process.
International journal of pharmaceutics, 2011
A Shirasu-porous-glass (SPG) membrane with a mean pore size of 2.5 μm was used to produce an oil/water (O/W) nanoemulsion of flurbiprofen consisting of methylene chloride as the dispersed phase, polyvinyl alcohol (PVA) as the stabilizer and a mixture of Tween 20 and Tween 80 in demineralized water as the continuous phase. Emulsion droplets with a mean droplet size of 25 times smaller than the mean pore size and a narrow droplet size distribution were produced using 5% emulsifier at a feed pressure of 15 kPa. Under these conditions the z-average diameter and size distribution of the emulsion droplets formed were influenced by the type of surfactant, agitator speed (150-1200 rpm), feed pressure (15-80 kPa), stabilizer concentration (0-4, w/v) and the temperature of the continuous phase. Increasing the agitator speed and stabilizer concentration increased the z-average diameter and decreased the size uniformity. There was a linear relationship between the increased feed pressure and th...