JP2597777B2 - Separation method of mixed solution - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for separating a mixed solution using a permeable membrane which may be called a vaporization permeation method.

[0002]

2. Description of the Related Art A method for separating a specific liquid component such as alcohol from a mixed solution in which two or more liquid components such as a mixed solution of water and alcohol are mixed by using a permeable membrane is called a pervaporation method. Methods are conventionally known. In this pervaporation method, the inside of the tank is partitioned by a permeable membrane into an upper solution chamber and a lower decompression chamber, and a mixed solution is introduced into the upper solution chamber, and the decompression chamber is brought into contact with the solution to the permeable membrane. By reducing the pressure, a specific liquid component in the mixed solution is preferentially permeated and diffused into the permeable membrane, and the liquid component that has passed through the permeable membrane is vaporized from the surface of the permeable membrane to the decompression chamber, In this way, by collecting the components in the decompression chamber that have been permeated through the permeable membrane, a specific liquid component can be separated and collected from the mixed solution. However, in this pervaporation method, the mixed solution is in direct contact with the permeable membrane, and generally the permeable membrane formed of a polymer material is often swollen by the mixed solution. When the permeable membrane is swollen in this way, the membrane function of the permeable membrane is reduced, and the separation performance of the mixed solution by the permeable membrane may be significantly impaired.

[0003] For this purpose, the present inventors have developed a technique which can also be referred to as a vaporization and infiltration method. A method for separating a mixed solution using the vaporization and infiltration method is disclosed in Japanese Patent Application Laid-Open No. 63-162003.
It is already provided in Japanese Patent Publication No. That is, in this method, as shown in FIG. 3, the decompression chamber 1 and the solution chamber 3 into which the mixed solution 2 is introduced are separated by the permeable membrane 4 so as not to contact the mixed solution 2, and the decompression chamber 1 is decompressed. Thus, the vapor of the mixed solution 2 generated in the solution chamber 3 is made to permeate the permeable membrane 4 and permeate from the solution chamber 3 side to the decompression chamber 1 side. In this method, since the permeable membrane 4 does not come into contact with the mixed solution 2, there is no problem that the membrane function is deteriorated due to the swelling of the permeable membrane 4, and the separation performance of the mixed solution 2 by the permeable membrane 4 can be improved.

[0004]

As described above, in the vaporization permeation method, the mixed solution 2 can be separated with a higher separation performance than the pervaporation method. Since the separation is performed by diffusing and permeating and permeating through the membrane 4, the speed at which the liquid component permeates the permeable membrane 4 is slow, and the liquid is permeated through the permeable membrane 4 at a sufficient permeation speed to perform liquid separation. However, there is a problem in productivity of liquid separation, and practical use is difficult.

The present invention has been made in view of the above points, and an object of the present invention is to make it possible to increase the permeation speed of a separated liquid to a practical level while maintaining high separation performance by a method based on vaporization and infiltration. It is assumed that.

[0006]

According to the method for separating a mixed solution according to the present invention, a mixed solution 2 is placed between a solution chamber 3 into which a mixed solution 2 in which a plurality of liquid components are mixed and a reduced-pressure chamber 1. The permeable membrane 4 is provided in a non-contact state, and the pressure of the decompression chamber 1 is reduced to allow the vapor of the mixed solution 2 generated in the solution chamber 3 to pass through the permeable membrane 4 from the solution chamber 3 side to the decompression chamber 1 side. In separating a specific liquid component from the mixed solution 2, a silicone porous membrane 4 a is used as the permeable membrane 4 , and
It is characterized in that gas is supplied into the liquid chamber 3 .

Hereinafter, the present invention will be described in detail. FIG. 1 shows an example of a principle apparatus for liquid separation according to the present invention based on the above-described vaporization and permeation method, in which a separation tank 5 is divided into an upper decompression chamber 1 and a lower solution chamber 3 by a permeable membrane 4. A space is formed between the liquid surface of the mixed solution 2 introduced into the solution chamber 3 and the lower surface of the permeable membrane 4 so that the mixed solution 2 does not come into contact with the permeable membrane 4. Is connected to a vacuum pump or the like to reduce the pressure.

In the present invention, the permeable membrane 4 is a silicone porous membrane 4 having a large number of pores communicating with each other.
a is used. As the silicone porous membrane 4a, any silicone resin membrane having communicating pores can be used without any particular limitation. For example, it is provided by the present applicant as Japanese Patent Application No. 3-171190. That is, an aqueous organopolysiloxane emulsion which forms an elastomer by removing water can be used by freezing and freezing, and then sublimating and drying water without thawing the emulsion. Further, it is preferable to use the silicone porous membrane 4a having pores having an average diameter in a range of 1 × 10 ⁻³ μm to 5 μm. If the size of the pores is larger than this, the number of components that pass through the pores without being affected by liquid separation by the silicone porous membrane 4a increases, and it becomes impossible to obtain high liquid separation performance. Things,
Conversely, if the size of the pores is smaller than this, the liquid component cannot easily pass through the pores, and the permeation rate of the separated liquid cannot be increased to a practical level. Here, in the present application, the diameter of the pore is defined as the diameter of this circle assuming a circle having the same area as the area of the pore, and the average diameter is defined as the average value of the diameter of each pore. Is what is done. Further, it is preferable to use a porous membrane having a ratio of pore area to the surface area, that is, a porosity of 5% or more. If the porosity is lower than this, the permeation amount of the liquid component is reduced, and it becomes difficult to increase the permeation rate of the separated liquid to a practical level.

In the present invention, the mixed solution is
For example, a mixed solution of definitive water and alcohol in the case of concentration and separation of alcohol from the fermentation alcohol, silicone
Liquid components with low affinity for
Use a mixture of highly compatible liquid components.
Liquid solution with high affinity for silicone
Minutes can be separated.

In the apparatus shown in FIG. 1, when the pressure in the decompression chamber 1 is reduced, the pressure in the solution chamber 3 is also reduced through the pores of the silicone porous membrane 4a. Vapor is generated, and the vapor of each liquid component reaches the silicone porous membrane 4a. Here, of the vapors of the respective liquid components that have reached the silicone porous membrane 4a, a liquid component having a high affinity for silicone , for example, alcohol, has an affinity for the surface of the silicone porous membrane 4a and easily passes through the pores, A liquid component that easily permeates the silicone porous membrane 4a from the solution chamber 3 side to the decompression chamber 1 side but has low affinity for silicone , for example
The example water hardly passes through the pores is repelled by the surface of the silicone porous film 4a, it can not be easily transmitted through the silicone porous film 4a from the solution chamber 3 side to the vacuum chamber 1 side. In this way, the liquid component having a high affinity for silicone among the liquid components in the mixed solution 2 is preferentially used for the silicone porous material 4.
To separate a predetermined liquid component from the mixed solution 2
A liquid having a high concentration of the liquid component can be obtained. At this time, the necessary liquid components are
When the liquid was separated by passing through 4a, it reached the decompression chamber 1
It is sufficient to collect the liquid, and conversely, unnecessary liquid components
Required by permeating porous material 4 and separating liquid
When leaving the solution in the solution chamber 3, the solution is removed from the solution chamber 3.
You only have to collect it.

When liquid separation is performed using the silicone porous membrane 4a in the vaporization and infiltration method, the liquid component to be separated is the silicone porous membrane 4a.
Then, the light is transmitted from the solution chamber 3 side to the decompression chamber 1 side through the fine pores. Therefore, compared with the case where the liquid component is diffused into the permeable membrane and permeated by diffusing the liquid component as in the case of the non-porous permeable membrane used in the vaporization permeation method described in Japanese Patent Application Laid-Open No. 63-162003, etc. The speed at which the liquid component passes through the silicone porous membrane 4a is extremely high, and a practical level of permeation speed can be obtained.

In the liquid separating apparatus shown in FIG. 1, a gas such as air can be introduced into the solution chamber 3. For example, as shown in FIG. 1 , a pipe 10 provided with a cock 9 and the like is connected to the inside of the solution chamber 3 so as to be introduced between the silicone porous membrane 4a and the liquid surface of the mixed solution 2, and the cock 9 is opened to open air. By supplying such a gas from the pipe 10, a gas such as air can be introduced into the solution chamber 3. The gas to be supplied into the solution chamber 3 is not limited to air, and various gases such as nitrogen gas can be used, and are not particularly limited. In performing the liquid separation operation by reducing the pressure in the decompression chamber 1 as described above, the cock 9 is further opened and the liquid separation operation is performed while gas such as air is supplied from the pipe 10 to the solution chamber 3. Thereby, the separation performance of the mixed solution 2 can be improved. Although the reason why the separation performance is enhanced is not clear, it can be considered as follows, for example. That is, the gas such as air supplied to the solution chamber 3 passes through the pores of the silicone porous membrane 4a and moves to the decompression chamber 1 because the decompression chamber 1 is depressurized. Gas molecules are generally much smaller than the vapor particles of the mixed solution 2 and easily penetrate and pass through the pores of the silicone porous membrane 4a. As a result, each liquid component of the vapor of the mixed solution 2 Is difficult to enter the pores of the silicone porous membrane 4a due to gas molecules and the vapor stays in the vicinity of the silicone porous membrane 4a, and separates the liquid by the silicone porous membrane 4a. , It is considered that the performance of separating the mixed solution 2 is enhanced. By supplying the gas into the solution chamber 3 in this manner, the concentration of the liquid component to be permeated and separated through the silicone porous membrane 4a can be increased. As a result, the separation performance is enhanced, and the concentration of the liquid component permeating the silicone porous membrane 4a can be increased. However, as the gas supply amount is increased, the liquid component becomes
The transmission speed becomes slow, and the transmission speed cannot be kept high. For this reason, the gas supply amount is preferably set in consideration of the balance between the liquid separation performance and the permeation speed in the silicone porous membrane 4a.

Further , by reducing the pressure in the pressure reducing chamber 1,
The interior of the solution chamber 3 is also evacuated through the cone porous membrane 4a.
Gas is supplied into the solution chamber 3 in a reduced pressure state.
When supplied, the gas expands rapidly in the solution chamber 3. Soshi
When the gas expands rapidly, the solution chamber
3 absorbs the heat and evaporates from the mixed solution 2
The liquid is cooled in the liquid chamber 3 and the vapor is in a state where it is easily condensed.
And the vapor of the mixed solution 2 passes through the silicone porous membrane 4a.
Can be slowed down. In this way, the gas
Silicone porous membrane can be cooled by thermal expansion
4a is used to separate the liquid components from each other,
And the ability to separate the mixed solution 2 increases,
It is also conceivable that there is not.

In performing the liquid separation operation as described above, it is preferable to heat the mixed solution 2 in the solution chamber 3 and cool the silicone porous membrane 4a. FIG.
In addition to heating the mixed solution 2 by dipping the solution chamber 3 in the heating bath 7, a heating jacket is attached to the outer periphery of the solution chamber 3, a heater is installed in the solution chamber 3, and the separation tank 5 is heated. Can be heated by any method or by any method. This heating may be performed by raising the temperature of the mixed solution 2 to at least a temperature higher than the ambient temperature in which the separation tank 5 is placed, and the heating temperature is not limited at all. Cooling of the silicone porous membrane 4a can be performed, for example, by attaching a jacket 8 around the silicone porous membrane 4a and passing a coolant through the jacket 8. This cooling may be performed as long as the temperature of the silicone porous membrane 4a can be kept lower than the temperature of the mixed solution 2 in the solution chamber 3. When the liquid separating operation is performed while heating the mixed solution 2 and cooling the silicone porous membrane 4a as described above, the liquid component having a different boiling point and a lower boiling point as the mixed solution 2 has a higher affinity for silicone. A mixture of two or more liquid components having a high boiling point and a low affinity for silicone, such as water and ethanol (boiling point 7
8.3 ° C.) and water and methanol (boiling point 6
(4.1 ° C.).

In this apparatus, when the mixed solution 2 in the solution chamber 3 is heated as described above in performing the liquid separation operation by reducing the pressure in the reduced pressure chamber 1, the boiling point of the components of the mixed solution 2 is reduced. The vapor arriving at the silicone porous membrane 4a has a high concentration of the liquid component having a low boiling point because the liquid component having a low boiling point is easily evaporated, and the liquid component having a low boiling point has an affinity for silicone. The low liquid is transmitted preferentially through the silicone porous membrane 4a, so that the concentration of the liquid component permeating and separating through the silicone porous membrane 4a can be increased, and the separation performance of the mixed solution 2 can be improved. it can. Moreover, at this time, the performance of separating the mixed solution 2 can be further improved by cooling the silicone porous membrane 4a as described above. Although the reason is not clear, when the vapor evaporated from the mixed solution 2 in the solution chamber 3 reaches the silicone porous membrane 4a, the liquid component having a high boiling point in the vapor is cooled by the cooling action of the silicone porous membrane 4a. The liquid component having a higher boiling point is more easily condensed than the liquid component having a lower boiling point, so that the liquid component having a higher boiling point is more likely to be associated and the aggregated form of the molecules becomes larger. It is expected that the liquid component having a low boiling point will permeate through the pores of the silicone porous membrane 4a more preferentially. By heating the mixed solution 2 and cooling the silicone porous membrane 4a in this manner, the concentration of the liquid component that permeates and separates through the silicone porous membrane 4a can be increased. At this time, when the silicone porous membrane 4a is cooled and the liquid separation operation is performed, the mixed solution 2 is heated and evaporated vapor acts on the silicone porous membrane 4a. 4a is heated by this vapor, and the effect of cooling the silicone porous membrane 4a cannot be sufficiently obtained. However, by supplying gas such as air to the solution chamber 3 as described above, Thus, the silicone porous membrane 4a can be cooled.

[0016]

The present invention will now be illustrated by examples. (Example) An aqueous silicone rubber liquid "SE-1980" manufactured by Dow Corning Toray Silicone Co., Ltd. was used as a dimethylpolysiloxane emulsion. The properties of this dimethylpolysiloxane emulsion are as follows: appearance: milky white liquid, solid content: 45% by weight, solvent: water, emulsion particle diameter:
0.5-1.0 μm, pH = 11.

[0017] After standing to defoaming dimethyl polysiloxane emulsion first under reduced pressure of 50 Torr 20 minutes this poured so as to thickness 2mm a Teflon Petri dish having a diameter of 95Mmfai, depth 15 mm, the upper surface of the petri dish The opening was sealed with aluminum foil and the sample was pre-cooled at a temperature of -6 ° C for 3 hours. Next, this sample was cooled to
The dimethylpolysiloxane emulsion was frozen by cooling in a refrigerator for 15 hours. After this,
The sample was taken out of the refrigerator and placed in a vacuum chamber of a freeze-dryer “VD-80” manufactured by Taitec Co., Ltd.
Under the conditions of 5 Torr and cold trap temperature of -80 ° C,
By vacuum drying for 6 hours without thawing, a silicone porous membrane having a thickness of 2 mm was obtained. This silicone porous membrane has a large number of bubbles having an average diameter of 70 μm and an average diameter of 3 μm.
m had open cells communicating with each other.

Using the silicone porous membrane 4a and 100cc of a water-ethanol solution containing 10% by weight of ethanol as the mixed solution 2,
The volume is 100 cc, the volume of the solution chamber 3 is 350 cc,
The mixed solution 2 in the solution chamber 3 is heated by a heating bath 7 at 40 ° C. and the silicone porous film 4a is formed using the apparatus of FIG. 1 in which the effective area of the porous membrane 4a is formed to 20 cm ² . Is cooled by the jacket 8 at 0 ° C., and the solution room 3 is emptied at room temperature (25 ° C.).
Air is supplied from pipe 10 at a supply rate of 180 cc / min.
And the pressure in the decompression chamber 1 was reduced to 10 ⁻¹ Torr.
By depressurizing with a vacuum pump , a liquid separating operation was performed, and a liquid in which the concentration of ethanol was increased in the decompression chamber 1 was collected and collected.

(Comparative Example) Using the silicone porous membrane 4 a obtained in the example and a water-ethanol solution containing 10% by weight of ethanol as the mixed solution 2, mixing in the solution chamber 3 was performed using the apparatus shown in FIG. The solution 2 is heated by a heating bath 7 at 40 ° C., the silicone porous membrane 4 a is cooled by a jacket 8 at 0 ° C., and the decompression chamber 1 is depressurized under a condition of 10 ⁻¹ Torr, thereby performing a liquid separating operation. Then, the liquid in which the concentration of ethanol was increased in the decompression chamber 1 was collected and collected.

(Conventional Example) A non-porous polydimethylsiloxane film (“SE-9520” manufactured by Dow Corning Toray Co., Ltd.) was used as a permeable membrane. Thereafter, a liquid separation operation was performed in the same manner as in the comparative example, and a liquid having a higher concentration of ethanol was collected and collected in the decompression chamber 1.

In Examples , Comparative Examples and Conventional Examples , the concentration of ethanol in the liquid recovered from the decompression chamber was measured as the concentration of the permeate, and the speed at which this liquid permeated through the permeable membrane was measured as the permeation speed. The coefficient α was measured. The separation coefficient α is defined by the following equation. α = (Y ₁ / Y ₂ ) / (X ₁ / X ₂ ) where X ₁ and X ₂ represent the weight fraction of ethanol and water in the mixed solution introduced into the solution chamber, and Y ₁ Y ₂ is shows the weight fraction and weight fraction of water in the ethanol solution was collected by vacuum chamber, respectively, thus the α is 1 or more numeric, liquid passes through the permeable membrane of ethanol This means that the amount is larger than the amount of water, and a larger value of α means that ethanol preferentially permeates the permeable membrane. Table 1 shows the results of these measurements.

[0022]

[Table 1]

As can be seen from Table 1, the conventional example using a non-porous permeable membrane has a good separation coefficient, but its permeation speed is extremely low, so that practical use is difficult. On the other hand, in the embodiment using the silicone porous permeable membrane,
Therefore, the transmission speed is at a practically high level. Ma
In the case of the comparative example in which air supply was not performed,
Practical application is difficult due to low temperature and low separation coefficient.
In the embodiment in which the supply of
Concentrations and separation factors remain at practically high levels.
As described above, the embodiment has a practically high level of transparency.
It is confirmed that overspeed and separation performance can be obtained .

[0024]

The present invention as described above according to the present invention, since as Ru a silicone porous membrane as a permeable membrane, of the vapor of each liquid component of the mixed solution reaches the silicon porous membrane affinity to silicone The specific liquid component with high affinity has an affinity for the surface of the silicone porous membrane and easily penetrates the pores,
Other liquid components having low affinity for silicone are repelled by the surface of the silicone porous membrane and are hardly permeated through the pores, and the silicone porous membrane can separate a predetermined liquid component from the mixed solution. The liquid component to be separated passes through the pores of the silicone porous membrane and is transmitted from the decompression chamber side to the solution chamber side, and the liquid component is separated like a non-porous permeable membrane. Compared to the case of permeating by diffusing and permeating through a permeable membrane, the speed at which the separated liquid component permeates the silicone porous membrane is extremely high, and a practical level of permeation speed can be obtained. It is.

In the present invention, since gas is supplied into the solution chamber, gas molecules much smaller than the vapor particles of the mixed solution generally easily enter the pores of the silicone porous membrane. As the gas enters and passes through the decompression chamber, the vapor of the mixed solution becomes a molecule of this gas.
It is difficult to enter the pores of the silicone porous membrane
The rate at which the vapor of the mixed solution passes through the silicone porous
And reduce the pressure in the decompression chamber.
Solution through silicone porous membrane by reducing pressure
The chamber is also under reduced pressure, and the solution under this reduced pressure
When gas is supplied to the room, the gas is rapidly
And the heat inside the solution chamber
Vapors from the mixed solution are absorbed in the solution chamber.
The mixture is cooled and becomes easily condensed,
Can slow down the speed of passing through silicone porous
It is a disturbing effect of gas molecules and gas insulation
Cooling action by expansion combined with silicone porous membrane
The liquid separation effect of each mixed component vapor
Can be used with a silicone porous membrane
To maintain a practical level of transmission speed
One, a mixed solution in which it is and this <br/> holding performance for separating a high level.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an improved example of a principle device for liquid separation by a vaporization permeation method used in the present invention.

FIG. 2 Principle of liquid separation by vaporization permeation method used in Comparative Example
It is sectional drawing which shows an apparatus .

FIG. 3 is a cross-sectional view showing a principle device of liquid separation by a vaporization permeation method.

[Explanation of symbols]

 1 decompression chamber 2 mixed solution 3 solution chamber 4a Silicone porous membrane

Claims (2)

(57) [Claims] 1. A permeable membrane is provided between a solution chamber into which a mixed solution containing a plurality of liquid components is introduced and a decompression chamber without being brought into contact with the mixed solution, and the decompression chamber is depressurized and generated in the solution chamber. When a specific liquid component in the mixed solution is separated by allowing the vapor of the mixed solution to pass through the permeable membrane from the solution chamber to the decompression chamber, a silicone porous membrane is used as the permeable membrane, and A method for separating a mixed solution , comprising supplying a gas . 2. A water-alcohol solution is used as a mixed solution.
The method for separating a mixed solution according to claim 1, wherein