JPS62244406A - Membrane separating method - Google Patents

Abstract

PURPOSE:To enable selective concentration of specific component and its easy separation by using a component to be separated and a compound forming a complex reversibly to concentrate the component inside large particles and separating the large particles with high-molecular porous membrane while being conveyed under static electric field. CONSTITUTION:For example, to separate acetone, trioctyl phosphate containing acetylene diol compound such as 1,1,6,6-tetraphenyl, 2,4-hexadiyne, 1,6-diol and the like and sodium lauryl sulfate are added to acetone water solution, and ultrasonic vibration is given to form particles of 0.1-10mum diameter. A potential difference is given between the surface of polytetrafluoroethylene porous membrane or the like and a liquid mixture, and by utilizing surface charge of particles, particles conveyed to the membrane surface and filtered with the membrane to separate particles. Only the phase of trioctyl phosphate permeates the membrane and acetone is concentrated in permeating liquid.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for membrane separation of specific component substances from a liquid mixture. In detail, there is a method in which large particles are transported in a liquid mixture under an electrostatic field and separated using a porous polymer membrane.
It is related to i.

BACKGROUND OF THE INVENTION Various techniques have been studied in the past for separating only specific component substances from a homogeneous liquid mixture, and the seven most widely used techniques at present are distillation methods.

However, near-boiling point mixtures and azeotropic mixtures require repeated distillation several times or azeotropic distillation to separate them into the same concentration, which requires a large amount of energy. Also,
Vacuum distillation or steam distillation is used to separate components that are easily decomposed at the same temperature near the boiling point, but this requires more energy than normal pressure distillation. Therefore, there is a need to develop a technology for separating liquid mixtures to replace the distillation method, and membrane separation methods are currently attracting attention.

Problems to be Solved by the Invention However, with the current membrane separation technology, if the separable woo crystals are used, the permeability is low.1. Alternatively, if the permeability is high, the separation is low, so it is necessary to compensate for the poor selectivity of both separation and permeability, and the former may be due to problems such as insufficient membrane strength, or the latter. This method had problems such as making the device complicated.

Under such circumstances, the present inventors investigated the relationship between the separation performance of substances and the average pore diameter of Hatake molecular membranes in order to realize a membrane separation technology for substances that increases both separation performance and permeability at the same time. , we have achieved this technology. In other words, as a result of careful investigation, we focused on the fact that the diffusion rate of molecules in liquids is 70~/θ3 times or more that in solids, and that the permeation rate of liquids through porous polymer membranes is high. The present invention has been achieved which can fully achieve the object.

Means for Solving the Problems In the present invention, in separating a liquid mixture, the target component is separated into large particles by using a liquid containing a compound that forms a reversible complex with the target component to be separated (hereinafter abbreviated as gearier).
This is a membrane separation method characterized by concentrating the large particles inside and transporting the large particles to the surface of the porous membrane under static conditions, while separating the particles using the porous membrane. First, the liquid mixture in the present invention is in a uniform one-phase liquid state under separation operation conditions. 2 components or more 1′, ′,
.

The invention is particularly useful for the separation of liquid mixtures or near-boiling liquid mixtures containing bodies. Examples of such liquid mixtures include aqueous solutions of alcohols such as methanol, ethanol, n-propertool, impropertool, 1-butanol, aqueous solutions of acetone, methyl ethyl ketone, tetrahydrofuran, dioxane, pyridine, acetic acid, etc. and methyl cyclo-xane/toluene, nuc [γhegisan/toluene'4 (7) mixed solution. Furthermore,
The present invention can also be applied to the separation of gases dissolved in liquids.

From such a liquid mixture, the component to be separated is concentrated inside large particles, and the surface charge of the large particles is used to cause particle transport under an electrostatic field, and the large particles are transferred to a porous polymer membrane. While transporting the particles to the surface, the particles are separated using a porous polymer membrane. Surface charging of large particles occurs due to the difference in dielectric constant between the particle liquid and the liquid mixture or localization of ion concentration near the interface, but a small amount of polar molecules may be added for the purpose of positively charging the particles. The average diameter of large particles at this time is 0.18 m ~
It is preferably in the range of 70 μm. Particle size is 0.7
If it is less than 11 m, the amount of movement due to Brownian motion of the particles will be small and the separation performance will be degraded.

:Next, when concentrating the target component to be separated from the liquid mixture into large particles, a liquid containing a carrier is used. Here, the carrier is a substance that is inert to substances other than the target component in the liquid mixture, selectively forms a complex only with the target component, and has such properties that this complex formation reaction occurs reversibly. Refers to a substance. When the target component is recovered from the complex formed by the carrier and the target component, the carrier remains and can be used as it is as a carrier.

Gears exhibiting such properties include, for example, when the liquid mixture is an aqueous solution of acetone, methyl ethyl ketone, etc.,
An acetylene diol compound such as goo-hexadiin-/, ot-diol or /, /, goo-tetraphenyl-coptine-7゜goo diol is added to a liquid mixture containing an alcohol such as methanol, ethanol, impropatol, t-butanol. In the case of an aqueous solution, fluoreteur compounds such as 9-fluorenol and de(/-propynyl) can be used. In addition, a liquid containing a carrier means that the carrier is θ, 0θ1 mol/l.
According to the membrane separation method of the present invention using a liquid containing such a carrier, this is achieved under thermodynamic equilibrium conditions. This is thought to be due to the fact that the rate of absorption of the particles into the interior of the particles increases, and the particles are separated by the porous polymer membrane before thermodynamic equilibrium is reached. When the carrier concentration in the carrier-containing liquid is less than θ, 007 mol/, the effect described above is small and there is little tendency for the target component to be trapped in the particles, resulting in a decrease in separation efficiency. Therefore, the carrier concentration is θ, θ01
It is preferable that the amount is mol/molar or more. In addition, in order to prevent the liquid containing the carrier from dissolving in the liquid mixture to be separated, for example, if the liquid mixture is an aqueous solution, the solubility of the liquid containing the carrier in water at 30° C./atmospheric pressure is o. , /(y/iθθ1) or less.

When the solubility in water exceeds θ, /, the liquid containing the carrier and the aqueous solution, which is a liquid mixture, partially form a phase! ], particles cannot be formed, and the recovery rate of particles decreases when particles are separated using a porous polymer membrane. Furthermore, by stirring a mixture containing a carrier-containing liquid, the component to be separated can be formed into large particles that gradually contract. By using the stirring method, it is possible to form extremely stable large particles!
Wear. The diameter of large particles can be set by adding a surfactant and controlling the stirring time, θ, 07 μm ~/θ
Large particles with a diameter of μm can be formed.

Inside the particles formed in this way, mass transfer at the particle/liquid mixture (matrix) interface causes l
] By using the surface charge of the particles to create a potential difference between the membrane surface and the liquid mixture, the particles are transported to the surface of the porous membrane, while the pressure difference on the groin side and Particles are separated by a porous polymer membrane using the interfacial tension difference between the particles and the matrix.

Here, the potential difference is a driving force that generates a force due to the surface load of the particles and efficiently transports the particles to the membrane surface.If the particles are positively bound, the membrane through which the particles permeate is A potential difference is provided in VN so that when particles are concentrated on the page, the membrane through which the particles pass becomes positive. By creating a potential difference between the membrane surface and the liquid mixture, the amount of particles passing through the porous membrane can be increased. In order to increase the surface charge of particles, it is effective to use an ionic surfactant during particle formation. Among them, the surface charge of particles is
, ':, J et al. prefer an anionic surfactant as the surfactant. The reason for this is unclear, but particle movement,
It is generated together with a secondary ion with the same charge as that of the song. When the surfactant is anionic, the secondary ion is hydroxyl, and when it is cationic, it is a hydrogen ion, and the interaction between hydrogen ion and hydroxyl ion. It is thought that particle transport efficiency is better when using an anionic surfactant than a cationic surfactant due to the difference in mobility. In addition, when the liquid mixture is an aqueous solution, HL
When particles are formed using an ionic surfactant with a valence of B or higher, separation of the surfactant can be achieved simultaneously with particle separation using a porous polymer membrane. In addition, surfactant HL Biichii (Hydrop) Lilic Lipophil
ic Balance) is Gr i f in
.

W, C, (J, 8oc, Cosmetic Chemi
sts, / (/9'19)) for nonionic surfactants, and later by Davies
(2nd Infer, Congress of
5urfaceActivity, / (/967
) ) now applies to all surfactants. The HLB value in the present invention is Dav
It is determined by the ies method.

Ionic surfactants with an HLB value of 1 or higher can be made stable. Furthermore, when F;- is passed through a hydrophilic A molecule porous membrane, only the matrix phase (liquid mixture) containing most of the surfactant permeates through the membrane. Particles formed using ionic surfactants with a value less than 111°B can also be separated by a weighted molecule porous membrane, but separation of the surfactant and particle phase is not always possible. The particles transported in this way can be separated into a particle phase and a matrix phase by a porous polymer membrane, making full use of the interfacial tension with the matrix phase that has phase-separated into an emulsion and the pressure difference on the crotch side. can.

Preferably, the porous polymer membrane in the present invention has an average pore diameter of 0.02 μm or more, a gravimetric porosity of 0.02 or more, and includes polyethylene, polypropylene, polyvinylidene fluoride, polytetrafluoroethylene, Porous polymer membranes made of polymers or copolymers such as polysulfone, polyvinyl chloride, polyvinyl alcohol, polyamide, and cellulose are suitable. Average pore size is 0.0.2μm
If it is less than 50 times the particle diameter, the permeability of the membrane will be low, and if it is 50 times or more the particle size, the particle phase and matrix phase will not be sufficiently separated.

Furthermore, the porous polymer membrane can be in any form such as a flat membrane, a tube shape, or a hollow fiber shape. The film thickness of these porous polymer membranes is /θμm~/ran
, preferably 70 to 2θθμm.

Depending on whether the liquid mixture system of large particles phase-separated in an emulsion and a matrix and the porous polymer membrane used are hydrophilic or hydrophobic, the large particles may pass through the membrane or the matrix may pass through the membrane. It is decided whether to do so. The present invention can be used in either case, and by using a hydrophilic and hydrophobic porous polymer membrane in combination, large particles can be rapidly separated. When the particle phase is an aqueous liquid and the matrix phase is a non-aqueous liquid, if a hydrophilic porous polymer membrane pre-wetted with water is used, the particle phase will pass through the membrane, whereas if a hydrophobic polymer porous membrane is used, the particle phase will pass through the membrane. The matrix phase permeates through the membrane. In addition, by using a hydrophilic membrane and a hydrophobic membrane pre-wetted with water, the particle phase permeates through the hydrophilic membrane, and the 7-trix phase permeates through the hydrophobic membrane, making particle separation more efficient. It is done. If, respectively, the particle phase is a non-small liquid and the matrix phase is an aqueous liquid, then the particle phase permeates through the hydrophobic membrane, and? The Yatrix phase permeates the hydrophilic membrane. Here, Ting: Uh,
A hydrophilic polymer porous membrane is one in which the contact angle exceeds 10 degrees when water droplets having a diameter of two groups or less are dropped onto the membrane surface at J, t° C./atmospheric pressure. In this way, the target component is recovered from the large particle phase separated by the porous polymer membrane in 1゛'1'j 7 trigrams, but the recovery at this time no longer consumes a lot of energy, so a distillation method is used. can do.

According to the method for separating a liquid mixture of the present invention, separation of a liquid mixture, which requires a large amount of energy in a distillation method, can be performed.
It can be converted to separation of a mixed liquid that can be easily separated by distillation.

Incidentally, the large particle diameter, porosity of the porous polymer membrane, and average pore diameter referred to in the present invention are measured by the following method.

(Method for measuring particle diameter) Optical elastic scattering method was used. That is, when a solution containing particles that undergo Brownian motion is irradiated with light, the frequency of light scattered from the particles exhibits the Doppler effect.

Therefore, by analyzing the temporal intensity changes in this light scattering market, the diffusion coefficient (D) of particles can be determined (for example, I), E, J (oppel, J, Chem, Phys.
S,! 7. uf/42 represents diameter.

” - (average pore diameter of porous polymer membrane) If the number of pores existing in the pore radius per porous membrane/cfl is r -r -1-dr is expressed as N(r)dr, then (N(r)
is the pore size distribution function), and the first-order average pore radius 〒i is given by equation (1).

An electron micrograph of the surface of the porous polymer membrane is taken using a scanning electron microscope. Calculate the pore size distribution function N (rl) from the photograph using a known method, and apply this to equation (1) as −//l
t- Substitute. That is, a scanning electron micrograph is enlarged to an appropriate size, for example, 20 cm x , 2θ/:rn) and printed, and 20 test lines (straight lines) are drawn at equal intervals on the obtained photograph. Each test line traverses multiple holes. Measure the length of the test line that exists inside the hole when it crosses the hole, and find this frequency distribution and function.

Using this frequency distribution function, for example 1, stereology (
For example, Norio Suwa's quantitative form? The uniform pore diameter is 2.3 (ie, t-3 in equation (1)).

(Porosity) From the measured value of the apparent density (ρa) of the porous membrane, the porosity (P r ) is calculated by the following formula.

Pr=(i-ρa/ρp＞×ioo+21 where ρp is the density of the porous membrane material, ρa is the weight of the porous membrane 1w
From the measured value of the volume V including the pores, ρa = W /
Calculated in V. In addition, Pr is a percentage table.

Examples Hereinafter, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited in any way by the following examples.

, Examples/~3, -/θ weight ratio Acetone aqueous solution 100- as a liquid containing a carrier/, /st, 1-tetraphenyl-2.
Goohegisadiin/, Otsu-diol 0. Trioctyl phosphate/θθ- and lauryl sulfate containing θ1 molar concentration) J Lamb 0. By adding /7 and changing the application time of 2t5' KI]Z ultrasonic vibration, trioctyl phosphate phase with a specific particle size formed particles, and an emulsion dispersed in an acetone aqueous solution was obtained. .

1:1:1 The emulsion was applied to a polytetrafluoroethylene porous membrane.

Ogi (manufactured by Sumitomo Electric ■FlojJ bore, nominal average pore diameter 10μm
)--7・:1 1i-%t, pressure θ, θhapaA゛inward gradient 3 V/
, passed the nnnn block. The results are summarized in Table 1.

By passing through a porous polytetrafluoroethylene membrane, only the trioctyl phosphate phase dispersed in particulate form permeated through the membrane, forming a continuous phase in the permeate. Further, as a result of analysis of the composition of the membrane permeate obtained in Example 2, the same procedure as in Example 2 was carried out except that the a degree of trioctyl phosphate was 0, and the a degree of ace]-6-diol was set to 0. The results at this time are also shown in Table 1. From Table 1, it can be seen that the separation factor increases by using a carrier.

Comparative Example The same procedure as Example 2 was carried out except that the potential gradient was set to θ. The results at this time are also shown in Table 1. It can be seen from Table 1 that by providing a potential gradient, the membrane permeability of the particles, that is, the P liquid flow rate increases significantly.

In Examples /, as a liquid containing a carrier /, /,
trioctyl phosphate containing g, gutetraphenyl/, 3-butyne-/, gudiol at θ, 1 molar concentration;
,6,10. /41-Tetramethylpentadecane mixed solution (,!:/weight ratio) Using 3-Oml, the potential gradient was set to ♂v
All procedures were carried out in the same manner except that the temperature was set to /cm. The results at this time are shown in Table 1. The composition of the obtained membrane permeate was 6% trioctyl phosphate, 9.3% acetone, and 7% water.

Comparative Example 3 Average particle diameter 0.7 μm according to Example/? An emulsion was obtained in which one particle of each molecule was dispersed. This emulsion has an average particle size V/,
The P liquid was not obtained. Pressure 0.
Or 5 and 9Apl produced lachrymal fluid, but this 7''
- □1 of 11!5. In the liquid, trioctyl phosphate remained dispersed in the form of particles.

Table 1 - Effects of the Invention As described above, according to the present invention, specific components can be selectively concentrated and easily separated from a liquid mixture that requires a large amount of energy for separation or a liquid mixture that is difficult to separate. be able to.

Claims (1)

[Scope of Claims] 1) In separating a liquid mixture, the target component is separated by 0.0% using a liquid containing a compound that reversibly forms a complex with the target component.
It is concentrated inside large particles with a diameter of 1 to 10 μm, and while the large particles are transported to the surface of a porous polymer membrane under an electrostatic field, they are separated using a porous polymer membrane with an average pore size of 50 times or less than the average diameter of the large particles. 2) Membrane separation method according to claim 1, characterized in that the liquid mixture is an acetone aqueous solution, and the compound that reversibly forms a complex with acetone is acetylene diol. Method 3) The membrane separation method according to item 1 or 2 above, characterized in that an ionic surfactant is used when forming the large particles that concentrate the target component.