WO2006120264A2 - Electrohydrodynamic device and method for the production of nanoemulsions and nanoemulsions thus produced - Google Patents

Electrohydrodynamic device and method for the production of nanoemulsions and nanoemulsions thus produced Download PDF

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WO2006120264A2
WO2006120264A2 PCT/ES2006/000220 ES2006000220W WO2006120264A2 WO 2006120264 A2 WO2006120264 A2 WO 2006120264A2 ES 2006000220 W ES2006000220 W ES 2006000220W WO 2006120264 A2 WO2006120264 A2 WO 2006120264A2
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liquid
jet
micro
dielectric
drops
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PCT/ES2006/000220
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Spanish (es)
French (fr)
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WO2006120264A3 (en
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Antonio Barrero Ripoll
Álvaro GÓMEZ MARÍN
Ignacio GARCÍA LOSCERTALES
Manuel MÁRQUEZ
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Universidad De Sevilla
Universidad De Málaga
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Priority to ES200501192A priority patent/ES2282009B1/en
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Publication of WO2006120264A3 publication Critical patent/WO2006120264A3/en

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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01FMIXING, e.g. DISSOLVING, EMULSIFYING, DISPERSING
    • B01F3/00Mixing, e.g. dispersing, emulsifying, according to the phases to be mixed
    • B01F3/08Mixing, e.g. dispersing, emulsifying, according to the phases to be mixed liquids with liquids; Emulsifying
    • B01F3/0807Emulsifying
    • B01F3/0815Emulsifying using heat, vibrations, electrical or magnetical energy
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01FMIXING, e.g. DISSOLVING, EMULSIFYING, DISPERSING
    • B01F13/00Other mixers; Mixing plant, including combinations of mixers, e.g. of dissimilar mixers
    • B01F13/0059Micromixers
    • B01F13/0061Micromixers using specific means for arranging the streams to be mixed
    • B01F13/0062Hydrodynamic focussing
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01FMIXING, e.g. DISSOLVING, EMULSIFYING, DISPERSING
    • B01F13/00Other mixers; Mixing plant, including combinations of mixers, e.g. of dissimilar mixers
    • B01F13/0059Micromixers
    • B01F13/0074Micromixers using mixing means not otherwise provided for
    • B01F13/0076Micromixers using mixing means not otherwise provided for using electrohydrodynamic [EHD] or electrokinetic [EKI] phenomena to mix or move the fluids
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01FMIXING, e.g. DISSOLVING, EMULSIFYING, DISPERSING
    • B01F3/00Mixing, e.g. dispersing, emulsifying, according to the phases to be mixed
    • B01F3/08Mixing, e.g. dispersing, emulsifying, according to the phases to be mixed liquids with liquids; Emulsifying
    • B01F3/0807Emulsifying

Abstract

The invention relates to an electrohydrodynamic method of generating double emulsions having a drop size in the micro or submicrometric range, of the water/oil/water (w/o/w) type, the oil/water/oil (o/w/o) type and oil/water (o/w)-type simple emulsions. The inventive method comprises the formation of an electrified compound jet in a bath of dielectric liquid [liquid(1)] having a diameter in the micrometric or submicrometric range, which is formed by a liquid (2) and a liquid (3) which flows inside the liquid jet (2) either in the form of drops or in the form of another inner jet. The inventive device and method can be used to obtain nanoemulsions and for encapsulation processes used in fields in which the generation and controlled manipulation of micro or nanometric drops and jets constitutes an essential part of the process.

Description

TITLE

DEVICE AND PROCEDURE FOR THE GENERATION OF NANOEMULSIONS VIA ELECTROHIDRODINÁMICA

OBJECT OF THE INVENTION

The present invention describes a method for generating, via electrohydrodynamics, double emulsions, with droplet sizes in the micro or submicron regime, of the water-oil-water (w / o / w) and oil-water-oil (o / w / o), and simple oil-water emulsions (o / w). The procedure consists in the formation, in a bath of a dielectric liquid [liquid (1)], of a composite electrified jet, of diameter in the micrometer or submicrometer range, formed by a liquid (2) and a liquid (3) that flows through the interior of the liquid jet (2), either in the form of drops or in the form of another internal jet. The liquid (2) is hydrophilic (conductive) and its nature is, therefore, different from that of the bath liquid (1), which is hydrophobic (dielectric liquid). The liquid (3) can be hydrophobic, or even hydrophilic in nature, although in the latter case the miscibility between the liquids (2) and (3) must be very low. The two liquids are injected through two capillary needles (or feeding tips) located concentrically, or one inside the other. When the conductive liquid (2) flows at appropriate flow rates and is subjected to an electric field, of appropriate value, a conical electrified meniscus (Taylor cone) is formed from whose vertex a stationary jet flows through the electric field action . For appropriate values of the flow injected through the needle and the electric field, it can be achieved that the cone-jet structure remains stationary (Figure 1), see for example Barrero et al. (2004).

This phenomenon is known in electrohydrodynamic literature as electrospray in stationary cone-jet mode. The diameter of the jet, which depends on the properties of the liquid (mainly the electrical conductivity) and the injected flow rate is between tens of nanometers and a hundred microns. If under these conditions, a stationary flow of the hydrophobic liquid (3) is injected through the inner needle, another meniscus is formed inside the anterior meniscus (2), see the photograph of figure 2. The arrangement of the needles is such that the dielectric liquid (1) partially or totally bathes the meniscus of the conductive liquid (2). The deformation of the inner meniscus by the action of the viscous forces of the movement of the liquid (2) that surrounds it results in the latter adopting a conical shape like the one shown in the photograph of Figure 2. If the hydrophobic liquid (3 ) small amounts of an appropriate surfactant are added, the interfacial tension between the liquids (2) and (3) decreases markedly and the viscous forces that the liquid (2) exerts on the liquid meniscus (3) break the conical tip of the inner meniscus to give rise to a second jet of liquid (3) flowing surrounded by the jet of liquid (2), see the photograph of Figure 3 and Figure 4a. The coaxial jet thus formed is unstable and breaks into the dielectric bath (hydrophobic liquid) resulting in a hydrosol of compound drops in which the hydrophilic liquid (2) encapsulates one or more drops of the hydrophobic liquid (3). Sometimes, the intermittent rupture of the tip of the hydrophobic meniscus (3) produces a train of small drops, instead of a jet, which are dragged by the liquid jet (2), see Figure 4b. In this case, the rupture of the jet results in liquid capsules (2) that enclose one or more drops of liquid (3) (multi-nuclear capsules). When the capillary through which the liquid is injected (3) has an internal diameter considerably smaller than that of the capillary used to inject the liquid (2), the liquid (3) is ejected in the form of drops (see Figure 4c) if the injected flow rate is below a threshold value (dripping), while for values greater than this it flows in the form of a jet of diameter substantially equal to that of the capillary (jetting), which finally breaks into drops that are dragged by the liquid jet (2), see figure 4d. As in the previous case, the breakage of the liquid jet (2) results in multi-nuclear capsules.

In all cases, the described procedure leads to a double emulsion of the type o / w / o in which drops of a hydrophilic liquid (2) containing inside a hydrophobic (3) are dispersed in a bath of another liquid also hydrophobic (1) which can be the same or different liquid as the encapsulation (3). The compound drops, with a hydrophobic liquid (3) enclosed by the hydrophilic (2), resulting from the rupture of the jet are characterized by being uniform in size (small Standard deviation) and the range of their average diameter, which is of the order of jet diameter, is in a range that, depending on the properties of the liquids (mainly of the electrical conductivity of the hydrophilic liquid), ranges from a few tens of nanometers, for the most conductive liquids, to a hundred microns for the least conductive.

For the formation of simple oil-water emulsions (o / w), a hydrophilic liquid bath [liquid (4)] is used as reference electrode on which the dielectric liquid (1) rests, due to its lower density. Due to the charge of its drops, the hydrosol of compound drops is forced by the electric field to move towards the hydrophilic liquid bath (4). Once the drops penetrate the bath, the outer liquid (2) dissolves in the liquid bath (4), resulting in an emulsion of micro or nanometric sized drops of hydrophobic liquid (3) dispersed within the liquid (4). The electric field is applied by establishing a potential difference between the needle if it is metallic (or feed tip) and a reference electrode connected to ground or to a reference potential. The reference electrode can have different geometric configurations, plate, ring, etc. In addition, the reference electrode may not be solid; for example, another conductive liquid (4), different or not from the liquid (2), which is immiscible or poorly miscible with the dielectric and is in contact with it through an interface can also be used. The device and the method, objects of the present invention, can be applied to obtaining nanoemulsions and encapsulation processes with applications in fields such as Materials Science (nanoemulsions of liquid crystals and other complex fluids), Food Technology and Pharmaceutical Technology (emulsions and encapsulations), etc., where the generation and controlled handling of jets and drops of micro or nanometric sizes is an essential part of the process.

STATE OF THE TECHNIQUE

Among the many procedures commonly used to generate stationary liquid jets and aerosols, this invention utilizes electrohydrodynamic forces (EHD). The phenomenon of dispersing a liquid in air by electrohydrodynamic forces has been known since ancient times. Among the many ways that are known, it stands out for the properties of the resulting aerosol (drops with diameters in the nanometric range and average diameter of the very uniform charged drops) known as electrospray. As is known, under appropriate operating conditions, anchored to a needle (or feeding tip), metallic or not, a meniscus is formed in a very approximately conical manner from whose apex a flow of liquid in the form of a micro or nano-cube is emitted stationary. The rupture of said jet produces a cloud of charged drops called electrospray in stationary cone-jet mode that has been widely studied (Cloupeau and Prunet-Foch, J. Electrostatics 22, 135-159, Fernández de Ia Mora and Loscertales, J. Fluid Mech. 260, 155-184, 1994; Gañán-Calvo et al. J. Aerosol Sci. 28, 249-275, 1997; Hartman et al. J. Aerosol ScL 30, 823-849, 1999). Recently, using electrospray techniques a procedure has been developed to produce electrified coaxial jets of liquids in which their breakage results in an aerosol of droplets composed of a liquid enclosing or encapsulating another, Loscertales et al. Science 295, 1695-1698, 2002, and PCT / ES02 / 00047. When the solidification of one of the two liquids that form the coaxial jet occurs before it breaks, the result consists of coaxial micro or nanofibers or micro / nanotubes. (Loscertales et. Al, J. Am. Chem. Soc. 126, 5376, 2004). The above results refer to the dispersion of a liquid in a vacuum or in a gaseous atmosphere but not in situations in which the dispersion process takes place within other liquids. In the liquid-liquid case, the development of cusps at the interface of two immiscible liquids when a sufficiently large electric field is applied has been analyzed by Oddershede and Nagel, Phys. Rev. Leu. 85, 1234-1237, 2000. In any case, this work neither investigates nor establishes, therefore, the conditions necessary to form a stationary and stable electrospray, in the cone-jet mode, of a liquid within other. The electroatomization of a liquid within another in the so-called drip (microdripping) regime applying pulsed electric fields has also been considered by Tsouris, Neal, Shah, Spurrier and Lee, Chemical Eng. Comm. 160, 175-197, 1997; Naturally, the use of non-stationary electric fields is incompatible with the stationary cone-jet mode (electrospray. Electrostatic atomization of dielectric fluids (such as air or organic solvents) within relatively conductive fluids (eg water) has been investigated also by Tsouris, Shin and Yiacoumi, Canadian J. Chem. Eng. 76, 589-599, 1998;

Sato, J. Colloid Interface ScL 756,504-507, 1993; see also US Patent 5,762,775 and US Patent 4,508,265. This situation, in which various electrohydrodynamic phenomena occur, is also incompatible with the formation of a stable and stable cone-jet structure.

Finally, the dispersion of a conductive liquid in another dielectric applying alternating electric fields has been considered in the following patents: US Patent 5,503,372, by W. G. Sisson ,, MT. Harris, T.C. Scott and O.A. They will base; US Patent 5,738,821 by W.G. Sisson, O.A. Basaran and MT. Harris; US Patent 5,759,228 by by W.G. Sisson ,, MT. Harris, T.C. Scott and O.A. They will base. As indicated above, the application of an alternating electric field is naturally incompatible with obtaining the stable, stable and stable cone structure, which is claimed herein and resulting in a monodispersed hydrosol of charged drops. More recently, Barrero et al. J. CoII. Interf. Sci. 272, 104-108, 2004 has obtained stationary electrosprays of a conductive liquid within a dielectric bath.

BRIEF DESCRIPTION OF THE FIGURES

Figure 1. Photograph of a simple glycerin electrospray anchored in a metal needle. In this case, no liquid is injected through the inner needle that is observed in the photograph. Note the very long jet of glycerin that is emitted from the apex of the electrified conical meniscus.

Figure 2. Photograph of a glycerin electrospray containing a silicone oil meniscus inside. Note the deformation of the meniscus of silicone oil, which takes the form of a conical tip, produced by the movement of the glycerin.

Figure 3. Photograph of an electrified composite jet in which the glycerin flowing outside contains another jet of petroleum jelly with a certain concentration of surfactant (Span 80). Figure 4. Scheme of the device used for the production of electrified composite jets, (a) The cusp of the inner meniscus emits a stationary jet of liquid (3) flowing through the interior of the electrified jet of liquid (2). (b) The cusp of the inner meniscus emits a train of liquid drops (3) that they flow inside the electrified liquid jet (2). (c) When the inner capillary has a diameter substantially smaller than the outer capillary and the flow injected through it is less than a certain threshold value, the liquid (3) is injected in the form of drops (dripping) that flow through the inside the electrified liquid jet (2). (d) When the inner capillary has a diameter substantially smaller than the outer capillary and the flow injected through it is greater than a certain threshold value, the liquid (3) forms at the exit of the capillary a jet (Jetting) that breaks by capillary instabilities in drops that flow inside the electrified liquid jet (2). Figure 5. Scheme of the device used to produce coaxial liquid jets of micro and nanometric sizes, within another liquid for obtaining double emulsions, with extraction of the fluid bath and the resulting hydrosol. Figure 6. Scheme of the two possible configurations for the creation of oil-in-water type emulsions (OAA / type emulsions). (a) Formation of a hydrosol H and precipitation of the droplets charged on the liquid electrode by electrical and gravitational forces. (b) Electrified jet composed by directly impacting on the reference liquid electrode. Figure 7. Current emitted through the jet as a function of the dispersed conductive liquid flow.

EXPLANATION OF THE INVENTION

The novelty of the present invention lies in the formation of a hydrosol of highly compound, charged monodispersed droplets, within a dielectric liquid [liquid (1)] from the breakage of an electrified jet in which a conductive liquid ( hydrophilic) that flows from the outside completely surrounds another dielectric (hydrophobic) that flows from the inside; The drops formed by the rupture of the jet have a structure in which the liquid (2) encapsulates the liquid (3). The liquids are injected through two needles (or feeding tips) arranged concentrically and immersed inside the liquid bath. The conductive liquid (2) is injected through the annular space between the two needles or tips so that when an electric field is applied a conical meniscus is formed electrified from whose vertex a stream of diameter flows in the micro / nanometric range. The characteristic conical shape of the conductive meniscus is due to a balance between the interfacial tension forces and the electrical forces acting on the surface of the conductive meniscus. The movement of the liquid (2) is caused by the electric tangential stress acting on the surface of the meniscus, driving the liquid (2) towards the tip of the Taylor cone. In the way known in the literature as cone-jet mode, the mechanical balance described above is no longer satisfied, so that the surface of the meniscus changes from conical to cylindrical (cone-jet). Inside this meniscus another dielectric nature (liquid 3) is formed, anchored to the inner needle, by slowly injecting the liquid (3) through it. This meniscus is deformed by the action of the viscous forces so that a cusp point is formed on its surface, from which a very thin stream of liquid (3) is emitted when the viscous forces overcome those of interfacial tension, see figure 4a . A composite jet structure is thus formed in which the conductive liquid (2), which flows outside the jet, completely covers the dielectric liquid (3), which flows inside. When the surface tension between both liquids (2 and 3) is not low enough, it is necessary to add a surfactant to break the surface of the inner meniscus and get the liquid (3) to flow to form the coaxial jet structure. Naturally, to reach a steady state it is necessary to provide both liquids at flow rates equal to those ejected.

When there is a balance between viscous forces and interfacial tension, the meniscus oscillates intermittently between a rounded vertex shape (without mass emission) and another with a cusp point from which drops of micro or nanometric size are emitted, see Figure 4b.

When the diameter of the inner capillary is very small compared to that of the outside, the injection of the liquid (3) into the meniscus of liquid (2) results in a drop train (dripping), figure 4c, or in a jet (jetting ) that breaks into drops, figure 4d. Both modes give rise to drops of diameter similar to that of the capillary. The electrified jet breaks downstream due to varicose instabilities associated with the surface tension resulting in a hydrosol, within the dielectric (1), of compound drops or composite particles, of very uniform size, in which the conductive liquid (2) encapsulates the dielectric liquid (3); emulsions of the oil-water-oil type (o / w / o) are thus obtained.

For the formation of simple oil-water emulsions (o / w), a hydrophilic liquid bath [liquid (4)] is used as reference electrode on which the dielectric liquid (1) rests, due to its lower density. Due to the charge of its drops, the hydrosol of compound drops is forced by the electric field to move towards the hydrophilic liquid bath (4). Once the drops penetrate the bath, the outer liquid (2) that forms the capsules dissolves in the liquid bath (4), releasing the liquid (3) and giving rise to an emulsion of micro or nanometric sized drops of hydrophobic liquid (3) dispersed within the liquid (4).

The electric field is applied by establishing a potential difference between the needle if it is metallic (or feed tip) and a reference electrode connected to ground or to a reference potential. The reference electrode can have different geometric configurations, plate, ring, etc. In addition, the reference electrode may not be solid; for example, another conductive liquid (4), different or not from the liquid (2), which is immiscible or poorly miscible with the dielectric and is in contact with it through an interface can also be used. Among the advantages of this invention, it is worth highlighting that the size of the compound drops can be controlled by varying the electrical conductivity of the conductive liquid (2). The range of sizes that can be achieved varies from one hundred microns to tens of nanometers. Another advantage of the invention derives from the fact that the rupture of the jet, micro / nanometric, produces drops, micro / nanometric and charged. The load of all the drops is always of the same sign, which avoids, by coulombian repulsion, the coalescence thereof. In addition, the local electric field acts on the net charge of each drop, helping very efficiently to extract the drops from the point where they occur, also avoiding their coalescence. Otherwise, the resistance offered by the receiving liquid to the displacement of micro / nanometric droplets would cause its accumulation at the point where they are formed, producing coalescence thereof, and losing not only the uniformity of the average droplet size, but also control over the size of the resulting drops. Another important advantage of the present invention is that from the point of view of applications (nano-encapsulation for example) lies in the fact that the control of the dispersed phase (compound drops) necessary for post-processing is much more versatile and easy to implement (pH, temperature, ultrasound, etc.) if the continuous phase is liquid instead of gas.

DETAILED DESCRIPTION OF THE INVENTION

The purpose of this section is to describe the device and the procedure for generating nanoemulsions via electrohydrodynamics. In particular, there will be developed here two applications focused on 1) the generation of double nanoemulsions of the type (o / w / o) in which capsules composed of a hydrophilic liquid containing another hydrophobe inside are dispersed in a continuous phase of a third liquid (also hydrophobic); this third liquid may be different or be the same as the encapsulation and 2) to the dispersion within a hydrophilic liquid of nanometric drops of a hydrophobic liquid, insoluble with the previous one; The interest of this application is that there is a good number of substances of high therapeutic value that are insoluble in water and when administered to patients, the levels of blood dissolution that are achieved are extraordinarily low unless this substance is dispersed in very small sizes in an aqueous liquid with the aim of increasing the surface between both liquids and facilitating the dilution of one in the other. The case of the formation of monodispersed emulsions of liquid crystal is another of the possible applications of interest.

The procedure and the device is common for both applications and passes through the generation in a dielectric bath [liquid (1)] of a jet of an electrified liquid through which another liquid co-flows, in the form of a jet or in drops form; the outer liquid is hydrophilic in nature and has a good electrical conductor (liquid 2) and the one that flows through the interior (liquid 3) is hydrophobic.

The device consists of two feeding tips A and B, concentrically arranged, or one contained in the other, and located within a dielectric liquid (1), as shown in Figure 5. A flow rate Q2 of a conductive liquid (2), or conductive liquid suspension, is injected through the existing play between the tips. The power tip B is connected to an electric potential V, through a source of electric potential HV, with respect to a reference electrode G. The reference electrode G, which can have varied geometric shapes (for example ring or conductive plate) is immersed in the liquid (1) and faces the supply tips A and B. A flow of liquid ( 1) it is simultaneously extracted and injected from the bath, see figure 5. If the feeding tip B is not metallic the conductive liquid is connected to the potential V through A. At the outlet of the feeding tip A an electrified meniscus is formed C with a substantially conical shape from whose apex a stationary capillary jet J of liquid (2) is emitted. A flow rate Q3 of a third liquid (3), immiscible or poorly miscible with the liquid (2) is injected at appropriate flows through the tip B, concentric with A. A second meniscus M of liquid 3, anchored at the outlet of The tip B is formed inside the meniscus C. The meniscus M develops a conical tip from which, depending on the interfacial tension of the liquids (2) and (3), a jet is emitted, or a train of drops , of liquid (3), flowing inside the liquid jet (2). A jet J is thus formed composed of the liquids (2) and (3) that flow coaxially within the dielectric liquid 1. The diameter of the composite jet is between 500 microns and 15 nanometers while the diameter of the inner jet (liquid 3), or drops, is between 200 microns and 0 nanometers. Due to capillary instabilities, the jet J breaks into a hydrosol of compound drops H so that the liquid (3) is encapsulated by the liquid (2). The average size of the compound drops is substantially uniform and is in a range of values that varies between 500 microns and 15 nanometers. The hydrosol is carried by the outgoing flow of liquid (1), see figure 5, and the emulsion is collected in an attached device. The supply tips A and B of the device must have a diameter between 0.01 mm and 5 mm and 0.002 mm and 2 mm respectively. The feed rate of liquid 2 (Q2) flowing through the clearance between feed tips A and B is between 10-15 m3 / s and 10-7 m3 / s. The feed rate of the liquid (3) flowing through the feed tip B is between 10-15 m3 / s and 10-7 m3 / s. When the distance between the supply tip A and the reference electrode G is between 0.01 mm and 50 cm, the applied electrical potential must be between 10V and 300KV. Thus, the device object of the invention consists of: a) Two feeding tips A and B located concentrically, or one of them contained in the other; a flow rate Q3 of a liquid (3) is fed by the tip B while a flow rate Q2 of the liquid 2 is injected through the clearance between A and B; tips A or B are connected to an electric potential V, if any of them metallic. If the tips are not metallic, the electrical contact can be made directly to the conductive liquid (2). b) A bath of a dielectric liquid (1) arranged so that the supply tips A and B are submerged in the liquid (1) and the potential V is a differential value with respect to an electrode G, also immersed in the liquid (1) and connected to a source of potential HV. Liquids (1) and (2) are immiscible or poorly miscible. At the outlet of the feeding tip A an electrically capillary meniscus C is formed, in a substantially conical manner, from whose apex a stationary capillary jet J of liquid (2) is emitted, so that the liquid (1) completely surrounds the liquid (2). A second meniscus M of liquid (3), anchored at the exit of the tip B, is formed inside the meniscus C. The meniscus M develops a conical tip from which a stream of liquid (3) is emitted, or a train drops of the same liquid, which converge with the liquid (2) to form a jet composed of both liquids. Said composite jet J has a diameter between 500 microns and 15 nanometers. The diameter of the liquid jet (3), or its drops, is between 200 microns and 0 nanometers; This last situation corresponds to the case in which no liquid (3) is injected through the feeding tip B.

The object of the present invention is the hydrosol H formed spontaneously by the rupture of the stationary capillary jet J that is formed using the mentioned device and procedure.

The object of the present invention is also the process described for the generation of jets and hydrosols when, instead of a conductive solid, a conductive liquid (4) is used as the reference electrode G. The liquids (1) and (4) must be immiscible and must form a separation interface with the heaviest liquid being below this interface. EMBODIMENT OF THE INVENTION

Embodiment example 1.

The basic apparatus used in this example consists of: (a) A means for supplying a first liquid (2) consisting of a metal tube A of 0.8 mm outside diameter and 0.4 mm inside diameter; In this example, the liquid (2) was glycerin.

(b) Another similar means for supplying a dielectric liquid (3) consisting of a glass capillary B with an external diameter of 0.36 mm and an internal diameter of 0.15 mm; in this case the liquid (3) was petroleum jelly with a certain concentration of oil-soluble surfactant.

(c) A RE container to contain the dielectric liquid of the bath [liquid (1)], immiscible with the liquid (2), and of very low electrical conductivity; in this case hexane has been used. The ends of the tubes B and A through which the liquids (3) and (2) flow respectively are immersed in the liquid (1);

(d) A reference electrode G, such as a metal plate or ring, located in front of the end of the tube A and also immersed in the liquid (1). The end of A and the reference electrode G were a distance of 1 cm;

(e) A high voltage source HV, with one of the poles connected to tube A and the other connected to the reference electrode G that is in contact with the liquid (1). The potential difference applied was in this case of 2 KV, as can be seen in Figure 5.

By way of illustration in Table I, experimental values of the intensity of current carried by the composite jet formed by a jet composed of liquid (3) flowing inside another jet of a conductive liquid (2) that surrounds it completely are given. and flows coaxially with the liquid (1). These data are collected in the curve of Figure 7 where the emitted current and the square root of the flow in the axis of abscissa are represented on the ordinate axis. The experimental data thus represented follow very closely the experimental law "Q1 / 2, which is common to all electrospray in the stationary cone-jet mode. As in electrosprays in a gaseous or empty atmosphere, our experiments in dielectric liquid atmospheres indicate that obtaining the stationary cone-jet mode requires operating with flows between two values. A lower one, which corresponds to the minimum ejectable from a liquid tip and a higher one that is fixed by the maximum load density compatible with the existence of a stationary jet. The rupture of the jet results in compound drops formed by a glycerin shell that encloses or encapsulates silicone oil. The drops that have a very uniform average size are dispersed in a dielectric liquid (1) and give rise to a double emulsion (silicone oil-glycerin-hexane) of the oil-water oil type (o / w / o).

Figure imgf000015_0001
Embodiment example 2.

In this case the purpose of the device is to disperse a hydrophobic liquid into a hydrophilic one, maximizing the contact surface between both liquids, thus creating an oil-in-water emulsion (o / w). For this, a device is used which is basically the same as in the example of embodiment 1, except that in this case the dielectric liquid of the bath (liquid (1)) rests on a layer of a fourth liquid, liquid (4), which is conductive (water for example) that is electrically grounded. There is thus a layer of hexane located on top of another layer of water as seen in Figure 6.

The basic device used in this example consists of:

(a) A means for supplying a first liquid (2) consisting of a metal tube A of 0.8 mm outside diameter and 0.4 mm inside diameter; in this example, the liquid (2) was glycerin; (b) Another similar means for supplying a dielectric liquid (3) consisting of a glass capillary B of 0.36 mm external diameter and 0.15 mm internal diameter; in this case the liquid (3) was petroleum jelly with a certain concentration of oil-soluble surfactant;

(c) A container RE1 containing a volume of a conductive liquid, liquid (4) (water in this example), on which the dielectric liquid of the bath rests (liquid

(one )); in this case hexane has been used. The ends of the tubes B and A through which the liquids (3) and (2) flow respectively are immersed in the liquid (1);

(d) The end of the tube A is immersed in the liquid (1) and located in front of the liquid (4) and at a distance of 1 cm; (e) A high voltage source HV, with one of the poles connected to tube A and the other connected to the liquid (4) that is in contact with the liquid (1). The potential difference applied was in this case of 2 KV.

The rupture of the jet (petroleum jelly on the inside and glycerin on the outside) ejected from the menisci leads to compound drops formed by a cover of glycerin that encloses or encapsulates the petroleum jelly. The compound drops dispersed in a dielectric liquid (1) are electrically charged and fall into the water under the simultaneous action of gravity and the electric field. Once the compound drops reach the water, the glycerin cover It disappears because it is soluble in water and submicron drops of petroleum jelly are obtained forming a second HA hydrosol, see Figure 6a. Another way of operating consists in appropriately reducing the separation distance between feed tips and the reference liquid electrode [liquid (4)] so as to avoid the breakage of the jet J (see figure 6b) so that the Ia is obtained directly emulsion of oil drops dispersed in water (emulsion o / w).

Claims

1.- Procedure and device for producing electrified composite jets of micro and submicron diameter in dielectric liquids and the double emulsion resulting from the varicose rupture of the micro / nano jet characterized in that the device consists of N = 2 feeding tips of 2 liquids (L1 and L2), arranged so that one encompasses the other, such that a flow rate Qi flows through each feed tip, i being a value between 1 and 2. Said feed tips are immersed in a dielectric liquid X , and connected to an electric potential Vi with respect to a reference electrode also immersed in the liquid X. For appropriate values of Qi and Vi, a liquid capillary meniscus with a substantially conical shape from whose vertex is formed is anchored at the outer tip. emits a stationary capillary stream of liquid (L2). Anchored at the inner tip a meniscus is formed from which a liquid (L1) flows, in the form of a jet or drops. A composite, capillary, stationary jet is thus obtained, so that the liquid (L2) surrounds or encapsulates the liquid (L1) and such that said capillary jet has a diameter between 500 microns and 15 nanometers that is substantially shorter than the length characteristic of the electrified liquid meniscus from which it emanates.
2. Devices for producing stationary liquid jets and compound droplets of micro and nanometric size within a dielectric liquid according to claim 1, characterized in that the 2 supply tips have diameters between 0.01 mm and 5 mm.
3, - Devices for producing stationary liquid jets and compound droplets of micro and nanometric size within a dielectric liquid according to claims 1 and 2, characterized in that the flow rates flowing through the supply tips are between 10-15 m3 / s and 10-7 m3 / s.
4. Devices for producing stationary liquid jets and compound droplets of micro and nanometric size within a dielectric liquid according to claims 1-3, characterized in that for a distance between each supply tip and the reference electrode between 0, 01 mm and 50cm, the applied electric potential Vi is between OV and 100KV.
5. Devices for producing stationary liquid jets and compound droplets of micro and nanometric size within a dielectric liquid according to claims 1-4, characterized in that the reference electrode is a conductive liquid immiscible with the dielectric liquid X.
6. Device for producing stationary liquid jets and particles of micro and nanometric size within a dielectric liquid according to claims 1-5, the number of feeding tips N = 1 and the device containing: a) a tip of supply 1 through which a flow Q1 of a liquid (1) flows and connected to an electric potential V1. b) a bath of a dielectric liquid (2) arranged in such a way that the supply tip 1 is surrounded by the liquid (2) and the potential V1 is a differential value with respect to a reference electrode connected to a reference potential, also immersed in the liquid 2. The liquids (1) and (2) are immiscible or poorly miscible, forming at the exit of the feeding tip an electrified liquid capillary meniscus with a substantially conical shape and from whose apex a capillary stream is emitted stationary formed the liquid (1), such that the liquid (2) completely surrounds the liquid (1) and such that said capillary stream has a diameter between 500 microns and 15 nanometers that is substantially smaller than the characteristic diameter of the electrified liquid meniscus from which emanates.
7. Procedure for producing stationary liquid jets and composite particles of micro and nanometric size within a dielectric liquid by means of a device according to claims 1-5 consisting of flowing Qi flows of j-th liquids through each of the N supply points, i being a value between 1 and N, and j being between 1 and M, with M ¡Ü N. Each of the supply tips is connected to a potential Vi with respect to a reference electrode, characterized in that The M-th liquid that circulates through the Nth feed point (the outermost one) is immiscible or poorly miscible with the dielectric liquid X, an electrified capillary meniscus with a substantially conical shape being formed at the exit of the N-th power tip. and from whose vertex a stationary capillary stream formed by the M-th liquid is emitted and such that said capillary stream has a diameter between 500 microns and 15 nanometers which is smaller than the characteristic diameter of the electrified liquid meniscus from which it emanates, spontaneously producing the rupture of the jet and giving rise to the formation of particles, of size between 500 microns and 15 nanometers, in which the M-th liquid encapsulates the rest of the other liquids.
8. Multi-component emulsions of micro or nanometric size formed by drops of a liquid M, resulting from the rupture of the jet obtained by the methods according to claim 7, which contain drops of an M-1 number of liquids inside. The diameter of the multicomponent drops is between 500 microns and 15 nanometers.
PCT/ES2006/000220 2005-05-12 2006-05-08 Electrohydrodynamic device and method for the production of nanoemulsions and nanoemulsions thus produced WO2006120264A2 (en)

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ES200501192A ES2282009B1 (en) 2005-05-12 2005-05-12 Device and procedure for the generation of simple and double nanoemulsions and microemulsions through electrified coaxial jets in dielectric liquid media.

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CN104645842A (en) * 2015-03-12 2015-05-27 重庆工商大学 Technical scheme of lubricating oil -water mixed emulsion blending oil tank

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WO2002060591A1 (en) * 2001-01-31 2002-08-08 Universidad De Sevilla Device and method for producing stationary multi-component liquid capillary streams and micrometric and nanometric sized capsules
ES2239861A1 (en) * 2002-04-05 2005-10-01 Universidad De Malaga Electro hydrodynamic disperser of conducting liquid in dielectric bath includes dielectric liquid and electrical charging of droplets formed by breaking of suspension

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WO2002060591A1 (en) * 2001-01-31 2002-08-08 Universidad De Sevilla Device and method for producing stationary multi-component liquid capillary streams and micrometric and nanometric sized capsules
ES2239861A1 (en) * 2002-04-05 2005-10-01 Universidad De Malaga Electro hydrodynamic disperser of conducting liquid in dielectric bath includes dielectric liquid and electrical charging of droplets formed by breaking of suspension

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WO2011023405A1 (en) * 2009-08-28 2011-03-03 Georgia Tech Research Corporation Method and electro-fluidic device to produce emulsions and particle suspensions
US9789451B2 (en) 2009-08-28 2017-10-17 Georgia Tech Research Corporation Method and electro-fluidic device to produce emulsions and particle suspensions

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