JP2008049267A - Method for demulsification of water-in-oil type emulsion using electric field - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem of conventional demulsification methods using electric field that electrodes for generating electric field have to be disposed in a container and it is difficult to dispose the electrodes in the case of small containers to be used in biochemical fields, and that a solution is contaminated with electrode materials or a solution is electrolyzed because the electrodes are always brought into contact with the solution in the conventional methods. <P>SOLUTION: Demulsification of a water-in-oil type emulsion can be carried out in a non-contact manner by applying electric field, preferably alternating current electric field, from the outside of a container. That is, electric field generated by applying voltage to electrodes set in the outside of a container made of a dielectric is applied to the water-in-oil type emulsion kept in the container to carry out demulsification. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a technique for demulsifying a water-in-oil emulsion. The demulsification technique of a water-in-oil emulsion is used, for example, for removing water from waste oil, removing water contained in crude oil, and the like. In recent years, research on the use of water-in-oil emulsions in biochemical and biological reaction fields has been conducted. In order to recover the substance reacted in the minute water droplets constituting the water-in-oil emulsion, a de-emulsification technique for the water-in-oil emulsion is required.

  A typical method for demulsifying a water-in-oil emulsion is centrifugation. This is a method of using a difference in specific gravity between a water component and an oil component to separate them by centrifugal force. Further, there are a method of adding a specific demulsifier (Japanese Patent Publication No. Hei 6-128558) and a method of using a filter (Patent Publication No. 2006-43487, Japanese Patent Publication No. 2005-199140).

  A demulsification method using an electric field has also been proposed (Japanese Patent Publication No. 10-43504, Japanese Patent Publication No. 7-24212, Non-Patent Document 1, Non-Patent Document 2). Methods other than the centrifugal method are methods for performing separation with a relatively large volume (for example, 1 to several liters).

J. et al. S. Eow et al. , Chem. Eng. J. et al. , 85, 357-368, 2002 J. et al. S. Eow, et al. , Chem. Eng. J. et al. , 84, 173-192, 2001

  In recent years, many attempts have been made to apply water-in-oil emulsions to biochemical and biological techniques. In this case, a small synthetic polymer container having a capacity of 0.1 ml to 1 ml is usually used. A water-in-oil emulsion is introduced into this container, and the reaction is carried out in small water droplets. Thereafter, in order to recover the reaction product, the product is recovered by demulsification. In such a case, a centrifugal operation is often used. However, in the centrifugal operation, it is necessary to move each container into a centrifuge, which is very troublesome when the number of containers increases. It is also difficult to automate a series of operations.

  On the other hand, in the demulsification method using an electric field published so far, it is necessary to arrange an electrode for generating an electric field in the container, and it is difficult to incorporate it in a small container as described above. . In addition, since the conventional method always has a structure in which the electrode and the solution are in contact with each other, there arises a problem that the solution is contaminated with the electrode material or the solution is electrolyzed.

  Centrifugation is an effective technique for separation. However, there are difficulties in the following points. The container holding part inside the centrifuge must be shaped according to the outer shape of the container. In order to maintain the center of gravity during centrifugation, it is necessary to always arrange the containers in a balanced manner. Also, as described above, when separating a plurality of containers, it is necessary to transfer each one into a centrifuge.

  As a result of intensive studies, the present inventors have found that a water-in-oil emulsion can be de-emulsified in a non-contact manner by applying an electric field, preferably an alternating electric field, from the outside of the container, thereby completing the present invention.

  That is, it has been found that a water-in-oil emulsion held in a dielectric container can be demulsified by applying an electric field formed by applying a voltage to a pair of electrodes placed outside the container. It was.

  Preferably, the container made of the dielectric is a container made of a synthetic polymer or glass, and has a capacity of 0.1 to 10 ml, and the voltage applied to form an electric field is an alternating voltage. In some cases, the present invention has been found to be particularly effective.

In order to simultaneously process a water-in-oil emulsion held in a number of containers, a plurality of containers are installed in an inter-electrode electric field space formed by a pair of electrodes, and the water-in-oil emulsion held in the container group In addition, the object can be achieved by applying an electric field formed in the electric field space.

Moreover, in order to perform the demulsification operation under the optimum temperature condition, the present inventors have found a method for demulsifying a water-in-oil emulsion in which a temperature adjusting function is added to the electric field space between the electrodes.

The present invention shows a technique capable of performing a plurality of simultaneous operations and continuous operations without performing a centrifugal operation, preventing contact between an electrode and a solution, and capable of demulsifying even in a small amount. By disposing the electrode outside the container, demulsification can be performed regardless of the outer shape of the container. Moreover, a plurality of containers can be simultaneously demulsified by installing a container group in an array in which electrodes are previously arranged. Moreover, it can demulsify without making the electrode and the solution in a container contact.

Hereinafter, the present invention will be described in more detail. In the present invention, the material forming the container that holds the water-in-oil emulsion to be demulsified is required to be a dielectric. Examples of the material forming the container include polyethylene, polypropylene, and poly-4. -Synthetic polymer materials such as methylpentene-1, polystyrene, silicone resin, polyacetal, glass, ceramic materials, and the like. However, as long as it is a dielectric material, it is not restricted to these.

The capacity of the dielectric container used in the present invention is required to be 0.1 to 10 ml. If the capacity of the container is less than 0.1 milliliter, the surface of the container with respect to the capacity of the container becomes excessive, water droplets generated in the demulsification process are not sufficiently combined, and demulsification becomes insufficient. On the other hand, if it is 10 milliliters or more, it takes a long time to combine the water droplets, which is not practical. An example of a container used in the present invention is illustrated in FIG. The container for holding the water-in-oil emulsion used in the present invention is not limited to this shape and size, but the container example shown in FIG. 1 holds 0.2 ml of the water-in-oil emulsion. Can do.

In the present invention, an electrode for applying a voltage to the water-in-oil emulsion held in a dielectric container is installed outside the container. In FIG. 2, aluminum tapes 1 and 2 are attached to the lid 5 of the 0.2 ml container shown in FIG. FIG. 2 shows that according to the present invention, a pair of electrodes 1 and 2 are installed outside a container 3 holding a water-in-oil emulsion, and a voltage, preferably an alternating voltage, is applied between the electrodes. An example in which a vertical electric field is applied to the water-in-oil emulsion 4 held in FIG. However, the electrode installation location, electrode material, and electrode shape in the present invention are not limited to this example.

In order to simultaneously process water-in-oil emulsions held in a large number of containers, a pair of electrodes (aluminum tape) 6 is installed on two opposing faces of a rectangular parallelepiped container 9 as illustrated in FIG. Thus, a horizontal electric field is applied to the water-in-oil emulsion held in the container 10 made of a plurality of dielectrics. That is, a plurality of containers are installed in an inter-electrode electric field space formed by a pair of electrodes 6 to which a voltage, preferably an alternating voltage is applied, and the water-in-oil emulsion held in the container group is formed in the electric field space. The purpose can be achieved by applying an electric field. At this time, an AC voltage 7 is applied to one of the pair of electrodes, and the other is grounded to form an AC electric field. However, the electrode installation location, the electrode material, the electrode shape, and the shape and size of the inter-electrode electric field space are not limited to this example. In addition, it is also possible to arrange electrodes above and below the rectangular parallelepiped container.

In addition, in order to perform the demulsification operation of the water-in-oil emulsion held in the container group under the optimum temperature condition, a heater can be installed in the electric field space between the electrodes and the temperature can be adjusted.

[Example 1]
A polypropylene microtube having a capacity of 0.2 ml (shown in FIG. 1) was used as a sample container. Place 200 microliters of rapeseed oil (containing surfactant Tween 80 (1% v / v)) and 5 microliters of aqueous solution (containing surfactant Triton-100 (0.1% v / v)) into the container. It was. The container was vibrated to emulsify the sample solution to obtain a water-in-oil emulsion. The pair of electrodes for applying an electric field adopts the shape shown in FIG. That is, aluminum tape (electrodes) 1 and 2 are attached to the lid 5 of the polypropylene container (microtube) and the vicinity of the emulsion liquid surface. By applying an alternating high voltage between the electrodes, a vertical electric field was formed inside the microtube. The power source used was a commercial frequency neon transformer (winding neon transformer) and an inverter neon transformer with a slidac connected to the primary side. The commercial frequency neon transformer can generate an alternating high voltage of 60 Hz, and the inverter neon transformer can generate a high frequency of 17 kHz. An AC high voltage was applied to the water-in-oil emulsion for 10 minutes and the state of demulsification was observed. The following results were obtained.

FIG. 4 shows the state of demulsification when an AC voltage of 5 kilovolts is applied using an inverter neon transformer (17 kHz). 4-a is before voltage application, FIG. 4-b is 3 minutes after voltage application, FIG. 4-c is 5 minutes after voltage application, FIG. 4-d is 7 minutes after voltage application, and FIG. 4-e is after voltage application. Shown after 10 minutes. At this time, the following behavior was observed and demulsification was confirmed. First, water droplets were arranged on the beads in the direction of the electric field (vertical direction), then the water droplets merged to form a large water droplet, and finally, the enlarged water droplet sank to the bottom of the microtube. It was confirmed that the emulsification was similarly performed when a commercial frequency neon transformer (60 Hz) was used. However, the de-emulsification of the water-in-oil emulsion was more effective when the high frequency inverter neon transformer (17 kHz) was used.

[Example 2]
The water-in-oil emulsion held in multiple containers was then simultaneously processed. A water-in-oil emulsion was demulsified by the method of Example 1 except that the electrode for applying an electric field having the shape shown in FIG. 3 was used. That is, by installing a pair of electrodes (aluminum tape) 6 on the inner walls of two opposing surfaces of a rectangular parallelepiped container 9, a horizontal electric field acts on the water-in-oil emulsion 10 held in the dielectric container. I let you. As a result, the following results were obtained.

FIG. 5 shows the state of demulsification when an inverter neon transformer (17 kHz) is used and an AC voltage of 9 kilovolts is applied. 5-a is before voltage application, FIG. 5-b is 3 minutes after voltage application, FIG. 5-c is 5 minutes after voltage application, FIG. 5-d is 7 minutes after voltage application, and FIG. 5-e is after voltage application. Shown after 10 minutes. At this time, the following behavior was observed and demulsification was confirmed. First, water droplets were arranged on the beads in the direction of the electric field (horizontal direction), then the water droplets merged to form a large water droplet, and finally the enlarged water droplet sank to the bottom of the microtube. It was confirmed that the emulsification was similarly performed when a commercial frequency neon transformer (60 Hz) was used. However, de-emulsification of the water-in-oil emulsion was more effective when the high frequency inverter neon transformer (17 kHz) was used.

FIG. 6 shows a comparison between the water-in-oil emulsion in Example 2 before voltage application and 10 minutes after voltage application. FIG. 6A and FIG. 6B compare the states before voltage application and 10 minutes after voltage application when the applied voltage is 13 kilovolts and 60 Hz. FIGS. 6-c and 6-d compare the states before voltage application and 10 minutes after voltage application when the applied voltage is 5 kilovolts and 60 Hz. 6-e and FIG. 6-f compare the states before voltage application and 10 minutes after voltage application when the applied voltage is 13 kilovolts and 17 kHz. FIG. 6-g and FIG. 6-h compare the states before voltage application and 10 minutes after voltage application when the applied voltage is 5 kilovolts and 17 kHz. In either case, it can be seen that the water-in-oil emulsion is de-emulsified by applying a voltage. When compared with the electrode arrangement, the amount of the aqueous solution separated into the bottom of the microtube was larger in the shape B (FIG. 3) than in the shape A (FIG. 2).

In particular, it may be used when water-in-oil emulsions are used in biochemical and biological techniques. In this case, it is very sensitive to contamination due to contact between the electrode and the solution, and combinatorial chemistry is often performed. In this case, it is necessary to process a plurality of containers at the same time. In addition, small containers such as those described above are often used. In such a case, it is considered that the demulsification method shown in this patent can be used.

Examples of containers for water-in-oil emulsions according to the invention Examples of electrode shapes according to the invention Description of electrode shape when processing containers according to the present invention Photo Example 1 showing the result of demulsification based on the present invention Photo Example 2 showing the result of demulsification based on the present invention Photo Example 3 showing the result of demulsification based on the present invention

Explanation of symbols

1, 2: Aluminum tape 3: Container made of dielectric material 4: Water-in-oil emulsion held in container 5: Container lid 6: Pair of electrodes 7: AC voltage 8: Ground 9: Rectangular container 10: Container Retained water-in-oil emulsions
11: Well plate holding container group

Claims (5)

  A method of demulsifying a water-in-oil emulsion held in a dielectric container by applying an electric field formed by applying a voltage to a pair of electrodes installed outside the container.   The water-in-oil emulsion according to claim 1, wherein the dielectric container according to claim 1 is a container made of a synthetic polymer or glass and has a capacity of 0.1 ml to 10 ml. Demulsification method.   The method for demulsifying the water-in-oil emulsion according to claim 1 or 2, wherein the voltage applied to form the electric field is an alternating voltage.   The water-in-oil emulsion according to claim 1, 2, or 3, wherein a plurality of containers are installed in an inter-electrode electric field space formed by a pair of electrodes, and an electric field is applied to the water-in-oil emulsion held in the container group. A method of demulsifying. The method of demulsifying the water-in-oil emulsion according to claim 4, wherein a temperature adjusting function is added to the inter-electrode electric field space according to claim 4.

Images