Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
  • B01F23/00—Mixing according to the phases to be mixed, e.g. dispersing or emulsifying
  • B01F23/40—Mixing liquids with liquids; Emulsifying
  • B01F23/41—Emulsifying
  • B01F23/414—Emulsifying characterised by the internal structure of the emulsion
  • B01F23/4143—Microemulsions
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
  • B01F23/00—Mixing according to the phases to be mixed, e.g. dispersing or emulsifying
  • B01F23/40—Mixing liquids with liquids; Emulsifying
  • B01F23/41—Emulsifying
  • B01F23/4105—Methods of emulsifying
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
  • B01F25/00—Flow mixers; Mixers for falling materials, e.g. solid particles
  • B01F25/40—Static mixers
  • B01F25/45—Mixers in which the materials to be mixed are pressed together through orifices or interstitial spaces, e.g. between beads
  • B01F25/452—Mixers in which the materials to be mixed are pressed together through orifices or interstitial spaces, e.g. between beads characterised by elements provided with orifices or interstitial spaces
  • B01F25/4524—Mixers in which the materials to be mixed are pressed together through orifices or interstitial spaces, e.g. between beads characterised by elements provided with orifices or interstitial spaces the components being pressed through foam-like inserts or through a bed of loose bodies, e.g. balls
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
  • B01F25/00—Flow mixers; Mixers for falling materials, e.g. solid particles
  • B01F25/40—Static mixers
  • B01F25/45—Mixers in which the materials to be mixed are pressed together through orifices or interstitial spaces, e.g. between beads
  • B01F25/452—Mixers in which the materials to be mixed are pressed together through orifices or interstitial spaces, e.g. between beads characterised by elements provided with orifices or interstitial spaces
  • B01F25/4524—Mixers in which the materials to be mixed are pressed together through orifices or interstitial spaces, e.g. between beads characterised by elements provided with orifices or interstitial spaces the components being pressed through foam-like inserts or through a bed of loose bodies, e.g. balls
  • B01F25/45241—Mixers in which the materials to be mixed are pressed together through orifices or interstitial spaces, e.g. between beads characterised by elements provided with orifices or interstitial spaces the components being pressed through foam-like inserts or through a bed of loose bodies, e.g. balls through a bed of balls
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
  • B01F2215/00—Auxiliary or complementary information in relation with mixing
  • B01F2215/04—Technical information in relation with mixing
  • B01F2215/0413—Numerical information
  • B01F2215/0418—Geometrical information
  • B01F2215/0431—Numerical size values, e.g. diameter of a hole or conduit, area, volume, length, width, or ratios thereof

Definitions

• the present invention relates to a process for manufacturing an emulsion.
• the present invention relates to a process for manufacturing an emulsion wherein instead of a membrane a packed bed of particles is employed.
• Premix membrane emulsification is an emulsion manufacturing process which has received much attention (cf. Suzuki, K.; Fujuki, I.; Hagura, Y., "Preparation of corn/oil and water/corn oil emulsions using PTFE Membranes", Food Sci. Technol. Int. Tokyo 1998, 4(2), page 164 ).
• a coarse premix emulsion having large droplets and a wide droplet size distribution of the dispersed phase is forced through a membrane with pores having a diameter in the micrometer range, wherein the droplet size as well as the droplet size distribution is reduced.
• Advantages of this process are low energy costs and a relatively high production rate.
• In-depth fouling must be prevented to maintain a reasonable throughput and a reasonably narrow size distribution of the droplets so that sophisticated pretreatments, maintenance and replacement of the membranes is often necessary.
• preventing in-depth fouling is not always possible, and when possible it often involves costly procedures and harsh cleaning conditions. It therefore limits the applicability of the process.
• US 2006/0102553 discloses an improvement of the membrane emulsification process, wherein the membrane is constructed from two or more superimposed layers having different pore diameters which would prevent blockage of the membrane due to its asymmetric structure.
• the effect of the asymmetric structure is mostly to reduce the hydrodynamic resistance of the membrane. Since the fouling components are part of the formulation, they have to pass the pores. These components will therefore still foul the membrane. Any reduction of the concentration of the fouling components by rejection or accumulation of the membrane either will alter the final product formulation, or will postpone the problems to a later stage (internal accumulation).
• US 2006/0128815 discloses a method for manufacturing an emulsion, wherein a dispersed phase is forced through a membrane having one or more orifices into a continuous phase, wherein the rate by which the dispersed face is forced through the membrane is interrupted by e.g. a wire or a plate located in the vicinity of the orifice.
• the components have to move through the membrane pores and thus will foul an ultimately block the pores.
• the present invention provides a solution to these problems, wherein the system is inherently robust against fouling of pores by the product components.
• the present invention relates to a process for manufacturing an emulsion, wherein a feed comprising a dispersed phase, a continuous phase and optionally an emulsifying agent is passed through a packed bed of, preferably essentially non-compressible, particles which are essentially inert to the dispersed phase, the continuous phase and the emulsifying agent, said particles having an average particle diameter in the range of 0.1 - 1000 ⁇ m.
• emulsion is well known in the art and comprises a mixture of two immiscible liquid substances.
• One substance is dispersed in the other (the continuous phase).
• examples of emulsions are butter, margarine and mayonnaise.
• butter a continuous phase (comprising at least a liquid (but also solids)) surrounds droplets of water (water-in-oil emulsion).
• Emulsions are unstable and thus do not form spontaneously. Energy input through shaking, stirring, homogenization, spraying or other processes are needed to form an emulsion. Over time, emulsions tend to revert to the stable state of oil separated from water.
• Homemade oil and vinegar salad dressings are examples of unstable emulsions that will quickly separate unless shaken continuously. This phenomenon is called coalescence and happens when small droplets recombine to form bigger ones. Fluid emulsions can also suffer from creaming, i.e. the migration of one of the substances to the top of the emulsion under the influence of e.g. buoyancy.
• emulsifying agent also known as emulsifier or emulgent
• emulsifier is to be understood as a component that stabilises the emulsion physicochemically. Usually, they are surface active substances or detergents which increase the kinetic stability of emulsions greatly so that, once formed, the emulsion does not change significantly over storage time. In food applications, egg yolk (contains lecithine) is often used. Emulsifying agents may also stabilise the emulsion by chemical interactions, e.g. as in the removal from grease by using soap.
• An important advantage of the process according to the present invention is that the packed bed of particles can be cleaned very easily.
• the bed is removed and resuspended by a short backflow; the individual particles can then - in suspension - be easily cleaned and re-used, or replaced by new particles. It is preferred that the particles are essentially non-compressible.
• the packed bed of the particles may comprise a support, which may be porous itself, e.g. a membrane or a sieve.
• the packed bed comprises a support, preferably a porous or permeable support.
• the support is provided with apertures having a mean diameter in the range of 0.1 to 1000 ⁇ m, more preferably 1 to 100 ⁇ m and most preferably 3 to 50 ⁇ m.
• the particles have an average particle diameter in the range of 1 - 1000 ⁇ m, more preferably 1 - 500 ⁇ m.
• the particle size distribution of the particles is preferably such that the smallest particles do not pass the support.
• the size distribution is adapted to the desired droplet size of the droplets of the produced emulsion.
• the standard deviation is about 0% to about 100%, more preferably about 0 to about 20 %
• the invention encompasses the option of applying a number (1 - 20) of successive layers of particles, each with a smaller particle size in the flow direction; thus in effect creating a packed bed with a gradient in particle sizes.
• a feed is employed wherein the ratio of the dispersed phase to the continuous phase (i.e. dispersed phase : continuous phase) is preferably in the range of 10 -4 to 10 4 v/v, based on the total volume of the feed. More preferably, this ratio is 10 -3 to 10 3 v/v, even more preferably 10 -2 to 10 2 v/v, yet even more preferably 10 -2 to 1 v/v, yet even more preferably 10 -2 to 0.5 v/v and most preferably 10 -2 to 0.20 v/v, based on the total volume of the feed.
• the feed comprises an emulsifying agent, preferably in amount of 10 -4 to 99.99 wt.% of an emulsifying agent, based on the weight of the continuous phase. More preferably, the amount of emulsifying agent is 10 -3 to 90 wt.%, even more preferably 10 -2 to 50 wt.%, and most preferably 10 -2 to 10 wt.%.
• the process can be repeated and preferably comprises 1 - 10 passes.
• the droplet size and the number of droplets in the emulsion can be further changed.
• viscosity and permeation behaviour is hardly affected.
• the feed is preferably passed through the packed bed of particles under a pressure of 100 Pa to 100 MPa, more preferably 100 Pa to 10 MPa, even more preferably 1 kPa to 10 MPa.
• the pressure drop ⁇ P over the packed bed is given by the Ergun relation [Van 't Riet, K., Basic Bioreactor Design, 1 st Ed., Marcel Dekker, Inc., New York, 1991].
• the Ergun relation appears to be a good estimation for emulsions.
• the pressure drop ⁇ p over the packed bed of essentially non-compressible particles is 100 Pa to 100 MPa. More preferably, the pressure drop is 100 Pa to 10 MPa and most preferably 1 kPa to 10 MPa.
• the pressure drop ⁇ p over the packed bed of essentially non-compressible particles as function of the flux J is preferably between 10 4 to 10 8 Pa/m.s -1 , more preferably between 10 5 to 10 7 Palm.s -1 .
• the packed bed comprises a support
• the pressure drop over the support must be taken into account as is apparent to the person skilled in the art.
• the packed bed according to the present invention can also suitably be used for separation purposes. Accordingly, the present invention also relates to a process for separating matter from a liquid phase, wherein the liquid phase is passed over (cross flow operation) or through the packed bed of particles (dead-end operation).
• the matter can for example be cells, macromolecules, emulsion droplets or other particulate material, wherein the matter is dispersed in the liquid phase.
• the liquid phase may comprise organic or inorganic liquid material.
• n-Hexadecane (99% for synthesis, MERCK) was used as dispersed phase. MilliQ water was used as continuous phase. As surfactant Tween 20 (for synthesis, MERCK) was used. The concentration was in all cases 0.5% v/w water phase. The hexadecane fraction was in all cases 5% (v/v).
• the premix was made by stirring the continuous phase, the surfactant, and the dispersed phase with a magnetic stirrer at -60 rpm in a 10 L flask for at least 1 day. The total volume of the premix emulsion varied between 3 and 8 liter, and in that way, a reproducible premix emulsion could be obtained.
• a fraction of 100HFL hydrophilic glass beads obtained by sieving between a 53 ⁇ m and a 125 ⁇ m sieve were used.
• the average particle diameter ( d 43 ) was measured to be 75.9 ⁇ m, and the span was 0.677.
• the particle density ( ⁇ p ) and bulk density ( ⁇ b ) were measured after sedimentation in water and found to be 2518 kg ⁇ m -3 and 1393 kg ⁇ m -3 respectively, resulting in a particle hold-up ( ⁇ ) of 0.553.
• the actual experiment started by pressurizing the emulsion vessel. All valves connecting the nitrogen vessel with the column were opened. The pressure was set with the valve connected to the nitrogen and read with the electronic pressure sensor (P). The outlet valve was opened and emulsification started; the homogenized emulsion was collected in a beaker on a balance connected to a computer, which recorded the mass output every second. The homogenized emulsion was recycled up to six times. The droplet sizes of the premix emulsions, and the homogenized emulsions were analyzed with the Mastersizer 2000 of Malvern. After the entire experiment, the particles were cleaned repeatedly (3-4 times) with hot water.
• the droplet size was fitted for various pressures, mass flows, number of passes, and energy densities as described in the theory and results section. All fits were conducted with the MATLAB least square fit function (lsqcurvefit) of the Optimization Toolbox and with the Mathcad minerr function. When both fits gave the same answer the standard deviation of the fit, the standard deviation of the fit parameters, and the correlation coefficient for the parameters were calculated.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Dispersion Chemistry (AREA)
• Colloid Chemistry (AREA)

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Cited By (4)

Citations (5)

• 2007
  • 2007-06-15 EP EP07110340A patent/EP2002882A1/de not_active Withdrawn

Patent Citations (5)

Non-Patent Citations (1)

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