JPS5892418A - Separation of liquid mixture - Google Patents

Abstract

PURPOSE:To enhance separation efficiency, in separating an org. liquid mixture by pervaporization, by using a high molecular thin membrance supported by a reinforcing support to make the thickness of the membrane thin. CONSTITUTION:Pref., to a porous support passing at least one component of an org. liquid mixture in a liquid form or a gaseous form, a high molecular membrane is bonded chemically, physically or by simple contact. As this reinforcing support, a material not deteriorated by the org. liquid mixture or the vapor thereof is used but, especially, a porous sheet or a porous film made of a synthetic resin is pref. and, for example, on the surface of this sheet, a high molecular resin, pref., a fluorine contained ion exchange resin is cast to obtain a composite membrane. This membrane is used as a separation membrane to carry out the separation or the concn. of the org. liquid mixture by pervaporization.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides at least an organic liquid with -
The present invention relates to a method for separating or concentrating a liquid mixture (hereinafter abbreviated as an organic liquid mixture) by using a specific polymer membrane using a barpaver system.

A process for separating organic liquid mixtures using non-porous, uniform polymeric membranes has been previously described in U.S. Pat.
This is taught in Specification No. 2, etc. This separation process is generally called a pervaporation process using a membrane, in which the liquid to be treated is supplied to the primary side (high pressure side) of the polymer membrane, and substances that are easily permeable are supplied to the secondary side (low pressure side). This is a method of preferentially transmitting it as vapor. This membrane separation method separates or concentrates liquid mixtures that could not be separated using conventional simple methods, such as azeotropic mixtures, mixtures with close boiling points and low relative volatility, and mixtures containing substances that polymerize or modify when heated. A new way to do this is attracting a lot of attention.

Conventionally, the polymer membranes used in such separation methods are polyethylene and polypropylene.

Cellulose polymer materials, polyacrylonitrile, polyamide, polyester, polystyrene.

Membranes made of polytetrafluoroethylene or copolymers thereof are known. However, when such a membrane is used to separate an organic liquid mixture by pervaporation, the following practical difficulties are recognized. That is, the amount of permeation of an organic liquid mixture through a polymer membrane (generally,
Since the membrane surface area (expressed as unit membrane surface area, unit membrane thickness, and permeation amount per unit time) is small, the membrane surface area must be made extremely large or the membrane thickness of the polymer membrane must be made extremely thin. Therefore, in the former case, the equipment cost becomes excessive, and in the latter case, problems arise in the strength and durability of the membrane.

The present inventor has conducted various studies on means for separating or concentrating various organic liquid mixtures by pervaporation.
As a result of repeated studies, it was discovered that the above-mentioned difficulties could be overcome by making the membrane a thin film and supporting it on a reinforcing support such as a porous support.

The present invention was completed based on the above-mentioned findings, and it separates a liquid mixture containing at least an organic liquid by pervaporation using a thin polymer film supported by a reinforcing support. The present invention provides a novel method for separating liquid mixtures.

The reinforcing support may be one that allows at least one component of the liquid mixture to pass therethrough in a liquid or gaseous state.
Although non-porous supports are also employed, porous supports with a large number of pores are usually preferred, preferably supports with a large number of pores that allow all components of the liquid mixture to be separated to pass through. It is the body. This support mainly serves to support and reinforce the membrane, and it solves the above-mentioned difficulties and makes it possible to significantly reduce the thickness of the membrane. This support can be present on both sides of the membrane, but is usually present on only one side. If the reinforcing support is present on only one side of the membrane, it may be present on the liquid mixture side or on the vapor side of the separated liquid. The membrane is preferably supported by the reinforcing support by chemically or physically bonding the reinforcing support, but it is also possible to support the membrane by mere contact without bonding. Chemical or physical bonding means include, for example, fusing or adhesion with an adhesive, a method of bonding the membrane and the support at a time when the membrane itself has fusible or adhesive properties at the stage of its formation; There are methods such as forming a membrane on a support, and sewing the membrane and support together with thread. In particular, the lightest method is to cast a liquid or dispersion of a polymer, which is the material for the membrane, onto a support to form a membrane on the support membrane.

The shape of the reinforcing support may be various shapes such as a flat membrane, a hollow fiber, or a cylindrical shape. The material is not particularly limited, and examples include synthetic resin, metal,
Examples include ceramics, other sheet-like materials and films, woven fabrics, non-woven fabrics, and other fibrous materials. Materials for the fiber body include synthetic fibers, natural fibers, and inorganic fibers such as glass fibers. Particularly preferred are porous sheets and films made of synthetic resin. This synthetic resin sheet or film may have pore sizes that differ in the thickness direction, that is, it may be an asymmetric porous membrane.
For example, it is manufactured by the method described in Japanese Patent Publication No. 56-3771 and the literature cited therein. The type of synthetic resin used as the material for the reinforcing support is not particularly limited as long as it is resistant to being attacked by the liquid mixture or its vapor. For example, polyolefin resin, polyvinyl chloride resin, fluorine-containing resin,
Polyester resin, polyamide resin, polysulfone resin, polyether sulfone resin, polyether resin, polyamideimide resin.

Polycarbonate resin, polystyrene resin.

Polyacrylonitrile resin, silicone resin.

Examples include polyvinyl alcohol resins, polyphenylene oxide resins, and cellulose derivatives.

The method of manufacturing the reinforcing support is also not limited. For example, in the case of a porous support made of synthetic resin, a method of casting a synthetic resin solution onto a sheet or film and immersing it in a coagulating liquid that is compatible with the solvent of the synthetic resin; There are methods such as manufacturing methods, elution of dissolved components from a sheet or film containing dissolved components, and hole-opening with a needle. Further, the porous support itself may also be reinforced with the above-mentioned fibers or the like. Although the pore size of the porous support is not particularly limited, if it is too large, the reinforcing effect of the membrane will be low, and if it is too small, it will be difficult for liquid or gas to pass through. Therefore, the pore diameter is preferably about 0.001μ to 5μ, particularly about 0.00μ to 5μ. Approximately OO3μ to 1mJ is appropriate.

The type of polymer membrane for separating the liquid mixture is not particularly limited, and the above-mentioned known polymer membranes can be used. Further improved polymer membranes include polymer membranes in which sulfonic acid groups are bonded to a polymer base, specific polyamide membranes, ionomer polymer membranes, etc. Publication No. 111889, 54-53278
No. 54-13279, etc., and these can also be used as the polymer membrane in the present invention. In addition, the present invention can be applied to various types of polymer membranes that can be used for pervaporation.

The performance of polymer membranes is evaluated by the separation coefficient below.

The evaluation revealed that the above-mentioned polymer membrane does not necessarily have a sufficient separation coefficient. In this sense, a polymer membrane with a high separation coefficient is desired as a polymer membrane in the present invention, and a fluorine-containing ion exchange resin having an acid type functional group is particularly suitable as a polymer membrane with a high separation coefficient. Understood. Therefore, as the polymer membrane in the present invention, it is preferable to use an acid-type functional base, containing, or fluororesin having ion exchange properties as described below.

In the present invention, the fluorine-containing ion exchange resin is preferably a resin made of a fluorine-containing polymer having an ion exchange group such as a carbo/acid group, a sulfonic acid group, a phosphoric acid group, or a phenolic hydroxyl group.

Such resins include, for example, tetrafluoroethylene,
vinyl monomers such as chlorotrifluoroethylene,
Those having a copolymer structure with a fluorovinyl monomer containing an ion exchange group such as sulfonic acid, carboxylic acid, or phosphoric acid group fx are preferred.

In particular, it is preferable to use polymers having the following structures (a) and (b).

(a) +OF2 cxx'+ -(b)
+0Fl-OX+here fX[F, O+, ) r or u
-cFI with Te, X' is X or OFs C0Ft
%, m is 1 to 5, and 1Y is selected from the following.

Z　　　　　　　I(.

Z　　　　　　　　　　I(.

xey*Z are both D~10, and Z.

R is selected from -F or a perfluoroalkyl group having 1 to 10 carbon atoms. Moreover, A is -C0OH.

-coo·'M, 80sH, SOs·1M, etc., or sow p which can be converted to these groups by one-step hydrolysis.

ON, OOF, 0OOR', 5Os
R' is an acid type functional group such as -CONR"R"S OsNR"R', M is a metal atom such as an alkali metal or alkaline earth metal or -N84R'R'R',
1 is the valence number of M, R1 is an alkyl group having 1 to 20 carbon atoms, and R''.

RA, R4, aI, n@ and R' 14 hydrogen i atoms or uR''i are shown.

In the present invention, the fluorine-containing ion exchange resin (hereinafter abbreviated as acid-type fluororesin) is composed of a fluorinated ethylenically unsaturated monomer (Il) and an acid-type functional monomer (Il).
It can be a copolymer with l. (As Il,
Tetrafluoroethylene.

Examples include chlorotrifluoroethylene, propylene hexafluoride, ethylene trifluoride, vinylidene fluoride, vinyl fluoride, etc. Preferably, the general formula OF! It is a fluorinated olefin compound represented by =OXX' (X and X' are as described above). Among these, perfluoroolefin compounds are preferred, and tetrafluoroethylene is particularly preferred. (Ill
is preferably a fluorovinyl compound of the general formula 0Fl-OXY (X and Y are as described above),
Preferably, CF*=OX-(OOFtOFR(), (0), (
OFR'f) rA (here ~p is 0-3.q is 0-1.
is an integer from 0 to 12, X - R1m A is as described above, and RIt is R. is a fluorine atom, Rf is -0Fs, R(
is a fluorine atom, and Q is 0 to 1. It is preferable that r is 0-8. Fluorovinyl compound (■
) is a preferable representative example of CF snow=CFO(OFs
). ~s 0OOR', OFO=OFO(CFx
) t~a OOF.

OFz =OF (OFtl.~*0O01'L"
.

C et al=OFOOF* OF (OFm) OOFm
CFx C0OR'.

CFx=OFOCFt OF (OFs)00F Goose O
FzOOF.

OFz = CFO (OFt) t ~ m 801F.

CF room = OFOOFz OF CCFs ) OOFm
Examples include CFx Sow F.

In the present invention, functional groups other than carboxylic acid type,
For example, reduction treatment of fluorinated copolymers having sulfonic acid type functional groups (% 1985-24175, 52-2417
6, see Publications No. 52-24177, etc.), oxidation treatment (I# Kaisho 53-132094, No. 53-13206)
A polymer obtained by converting a sulfonic acid type functional group into a carboxylic acid type functional group by, for example, Japanese Patent No. 9, may be used as the specific acid type fluororesin. Of course, the acid type functional monomer ( It may also be used as (It).

Furthermore, in the present invention, two or more of the above-mentioned (Il, (Ill), (a) and (b)) can be used as the constituent units of the specific acid type fluororesin, and In addition, other components such as olefin compounds such as ethylene, globylene, and iptylene, OP*=
Fluorovinyl ethers such as CFOQ (Q Fi represents a perfluoroalkyl group having 1 to 10 carbon atoms), OF
m = CF OFmOFi - CF2 = OFO(OF
鵞) I~a OOF= (3F! Chloquine vinyl monomer and others can also be used alone or in combination of two or more.

In the present invention, the content of the acid type functional group in the acid type fluororesin can be adopted over a wide range, and is selected from a wide range of 0.01 to 6 meq/Durum dry resin in terms of ion exchange capacity.

The ion exchange capacity is preferably about 0.1 to 2.2 meq/g dry resin. In addition, from the viewpoint of mechanical strength as a polymer membrane, the molecular weight of a specific acid type fluororesin is 50°C or higher when expressed by the TQ value described below.
The temperature is preferably about 70 to 600°C.

In this specification, the term "TQ" is defined as follows. That is, the temperature at which the volume flow rate of 100 j/sec, which is related to the molecular weight of the polymer, is defined as TQ. In this case, the volume flow rate is determined by using a polymer with an acid type functional group of methyl ester type such as 10000 H2 group, and applying the polymer to 30 to 9/- under pressure at a constant temperature for 1藺.

The amount of polymer melted and flowed out from an orifice with a length of 21 J is expressed in units of wo/sec. Also,"
The ion exchange capacity was determined as follows. That is, a specific acid-type fluororesin whose acid-type functional group is H-type, such as 10 0 Wash thoroughly with water to prevent stains. Then, 0.5 g of this H-type resin was added to 0.
．． It was left standing at room temperature for 2 days in a solution prepared by adding water 25117 to 1N NaOH25-. Next, the resin is taken out and the amount of NaOH in the solution is determined by back titration with 0.1N Hot water.

In the present invention, the acid type fluororesin described above is used alone or, if necessary, various additives are added to form a film. This polymer membrane does not necessarily need to be formed from only one type of acid type fluororesin, nor does it need to have only one type of acid type functional group. For example, two types of polymers may be used in combination for the ion exchange capacity, or a blend membrane may be used in which a weakly acidic functional group such as a carboxylic acid group and a strongly acidic functional group such as a sulfonic acid group are used in combination. For film formation, various conventionally known methods can be employed. Film formation is performed by forming a film from an aqueous dispersion or an organic solution of an acid type fluororesin by a casting method. Further, it is possible to form a film by heating and melting and extrusion molding, press molding, etc. In the latter case, when forming a film by hot melt molding, the ion-exchangeable acid-type fluororesin is used in the form of an appropriate ion-exchange group that does not cause decomposition of the ion-exchange group it has, for example, in the case of a carboxylic acid group, an acid or It is preferable to use the ester type, and in the case of a sulfonic acid group, it is easier to use the 18OIF type.

The polymer membrane used in the present invention, particularly the polymer membrane made of the fluorine-containing resin having acid-type functional groups, is a non-porous, uniform membrane, and its thickness is preferably about 1 to 250 microns. be. In particular, in the present invention, since the polymer membrane is supported by a reinforcing support, a relatively thin membrane within this range of thickness can be advantageously employed. Further, the shape of the polymer membrane can be adapted to the shape of the support, and can be of course a flat membrane as described above, but also a hollow fiber shape or a cylindrical shape. Furthermore, in order to increase the membrane surface, for example, in the case of a flat membrane, it can be bent into a folded shape.

The method of the present invention is carried out using an apparatus partitioned into a secondary chamber and a secondary chamber using the above-mentioned specific acid-type fluororesin membrane. −
The next chamber contains the organic liquid mixture to be separated or concentrated in liquid form, and the water chamber is evacuated in a suitable manner or other liquids or gases are circulated. In this way,
The organic liquid mixture is passed through a polymer membrane and separated or concentrated by pervaporation. - The liquid inside the next chamber is preferably circulated externally or internally, or - agitated by providing a suitable stirring device inside the next chamber. The specific polymer membrane is held in a suitable manner to partition the primary chamber and the secondary chamber, but it is advantageous in terms of durability if it is supported by, for example, a perforated reinforcing plate. - Substances that have permeated the polymer membrane from the next chamber are taken out from the second chamber and collected. It is usually desirable to appropriately heat the secondary chamber and/or the secondary chamber using a suitable heating device, such as a heating jacket.

The separation method of the present invention is carried out over a wide range of temperatures, typically from 0 to 200°C, preferably from room temperature to 100°C.
Selected from a range of degrees.

If the temperature is too high, problems will arise in maintaining the shape of the polymer membrane, and if the temperature is too low, the amount of liquid permeated will be small. Generally, the amount of permeation can be increased at high temperatures, but the concentration ratio (separation coefficient) due to membrane permeation becomes smaller. Further, the usable pressure range is usually vacuum to 100 kg/d, preferably vacuum to 30 kg/cJ, and if the pressure is too high, it becomes difficult to maintain the shape of the polymer membrane.

The organic liquid mixtures that can be separated by the method of the present invention include various combinations, such as mixtures of organic substances that cannot be separated by normal distillation methods because of the presence of azeotropic points, and mixtures of organic substances that cannot be separated by ordinary distillation methods because their boiling points are close to each other. This method is particularly effective in the case of mixtures of organic substances that are difficult to separate by distillation. Further, the organic liquid mixture may be entirely dissolved in each other uniformly, or a part of the organic liquid mixture may exceed the solubility and precipitate into a suspended state.

However,) the organic liquid mixture must be in a liquid state in its mixed state within the above-mentioned operating temperature range and at normal pressure or within the employed pressure range.

Examples of such organic liquid mixtures include benzene/cyclobenzene and benzene/n as mixtures in which an azeotropic point exists.
- Mixtures of organic substances such as hexane, methanol/acetone, benzene/methanol, acetone/chloroform; water/inozolopanol, water/ethanol, water/n
-Glopanol, water allyl alcohol water/2-methoxyethanol, water/imbutanol.

Water/n-butanol, water/2-butanol, water/furfuryl alcohol, water/n-pentanol, water/2-
Examples include water/alcohol mixtures such as pentanol and water/4-methyl-1-butanol; water/organic solvent mixtures such as water/tetrahydrofuran, water/dioxane, and water/methyl ethyl ketone.

In addition, as mixtures whose boiling points are close to each other, ethylbenzene/styrene, p-chloroethylbenzene/
p −= Chlorstyrene, toluene/methylcyclohexane, butadiene/butenes, butadiene/butanes, n-butene/I-butene, and the like. others,
Water/glycerin, water/glycols, water/propylene chlorohydrin, water/propylene dichlorohydrin, water/
Examples include epichlorohydrin, water/hydrazine, and isomer mixtures.

Furthermore, the method of the present invention can be applied to these mixtures not only in the two-component system as described above but also in multi-component systems such as a ternary or more component system. Of course, the method of the invention can also be applied to mixtures containing organic and inorganic substances, such as wastewater containing organic liquids.

The mixing ratio of the liquid mixture to be treated can be changed within an arbitrary range, but in general, the closer the ratio is to the equivalent situation, the higher the concentration ratio will be. If the desired purity cannot be obtained by passing through a polymer membrane once (-membrane concentration), pass it through a similar device multiple times (multi-stage concentration).
It is also possible to concentrate or separate the organic liquid mixture to the desired degree.

Examples of the present invention will be described in more detail below, but it goes without saying that the present invention is not limited by such explanations.

Example 1 1 ion-exchanged water was placed in a 0.2-base stainless steel pressure-resistant reaction vessel.
00 g %Os Flt C00N)L 0.2g5
Na! HPO1・12I (jO 0.5 g s Na
H! PO4'2'tb O 0, 3 g s INH
a) Prepare 0.026g of s St Ox, then 2
0g OFt = (3FO(OF)s 00001-
I prepared 1s. After sufficiently degassing with liquid nitrogen,
The temperature was raised to 57°C, and tetrafluoroethylene was introduced to 11.0 Kf/- to carry out a reaction. During the reaction, tetrafluoroethylene was continuously introduced into the system and the pressure was increased to 11. It was maintained at OKp/C-. After 4.5 hours, unreacted tetrafluoroethylene was purged to terminate the reaction. Furthermore, unreacted CFt=OFO(C
Ft ) i 0000Hs was extracted and separated by adding trichlorotrifluoroethane to obtain a stable aqueous dispersion having a concentration of 19% by weight. OF2 in copolymer = OFOfO
The composition of Liao 0000Hs was 20.6 mol. The aqueous dispersion was separated into an aqueous medium and a polymer concentrated layer using a centrifuge.

The aqueous medium layer was removed, the same amount of water was newly added, and the centrifugation operation was repeated again. The operation was repeated three times to remove the electrolyte used in the polymerization. Next, 15 g of a mixed solvent of N-methylpyrrolidone and methanol (N-methylpyrrolidone/methanol - 2.5/1 weight ratio) was added to the concentrated layer to form a dispersion, and the centrifugation operation was repeated again. Finally, add the organic solvent of the above composition to the concentrated layer again to obtain a copolymer concentration of 20.
A non-aqueous dispersion of % by weight was prepared. The viscosity of the dispersion is 10
It was 00 centiboise.

This dispersion was cast onto the surface of a commercially available porous polysulfone resin membrane (UK-501 manufactured by Toyo P Paper ■), and further dried at 120°C for 30 minutes to form an ion exchange capacity of 1.46 meq on the polysulfone resin membrane. /g of polymer thin film was produced.From the change in weight of the film before and after film formation,
The thickness of the thin film on the polysulfone resin film was estimated to be 5μ.

The membrane thus obtained was immersed in a 1N aqueous hydrochloric acid solution at 90° C. for 16 hours, washed with water, and dried at room temperature. This membrane was further immersed in a 1N aqueous sodium hydroxide solution at 60° C. for 16 hours, washed with water, and dried at room temperature to finally obtain a membrane in which the 1000 OHI groups on the membrane surface were changed to 100 ON a groups.

Using this membrane, a 95% by weight ethanol aqueous solution was used as the stock solution, the separation temperature was 65°C, and the ethanol aqueous solution side (primary side)
A separation test by pervaporation was conducted under the conditions of a pressure cuff of 60 as Hg and a pressure of 3 w Hg on the reduced pressure side (secondary side). As a result of analyzing the liquid composition and liquid weight trapped in the liquid nitrogen trap, the liquid composition was 70.4% by weight of ethanol, the separation coefficient was 8.0, and the permeation rate to the secondary side was 4600 g / It was m'・hr.

Example 2 The same procedure as Example 1 was carried out except that a non-porous polyester resin film (thickness 25 μm) was used instead of the porous polysulfone resin film.
A membrane supporting a polymer having ON a groups with a thickness of 10 μm was obtained.

A mixed solution of water and Impropatool pervaporated using a film (Isopropatool/Water-82/1B
, weight ratio) were separated. Temperature 65℃, permeate side pressure 3wH
The separation coefficient of water for isopropanol obtained at g is 220 and the permeation rate is 970 g/rrt
・It was hr.

Example: Tetrafluoroethylene and 0F1=OFO(CF*)-s 0
Composed of a copolymer of 00CHs and has an ion exchange capacity of 1.4
Polymer powder having 3 meQ/gf was added to 1 volume/volume of acetic acid.
It was immersed in a solution consisting of 1 volume of 2N hydrochloric acid at 60°C for 16 hours.
Dry as a base. A mixture of 100 parts by weight of the acid type polymer, 60 parts by weight of decyl alcohol, and 2 parts by weight of concentrated sulfuric acid was heated at 110° C. for 12 hours to convert the functional groups into decyl ester types. The decyl ester type polymer 5
The weight part is P-1'loropenzotrifluoro, siloid 9
The mixture was added to 5 parts by weight, heated to 100°C to dissolve, and then cooled to 60°C to obtain a 5 weight i% solution of the decyl ester type polymer.

Using this solution in place of the dispersion in Example 1, a 5μ thin film was formed on a porous polysulfone resin membrane in the same manner as in Example, and a Borrimer thin film having 00ON a groups was supported on the membrane surface. A membrane was obtained.

A separation test by pervaporation similar to that in Example 1 was conducted using this membrane, and the result was that the separation coefficient was 78 and the permeation rate was 5200 g/--h.

Procedural amendment form) April 1980 Haruki Shimada, Commissioner of the Japan Patent Office1, Indication of the case, Patent Application No. 190706, filed in 19822, Name of the invention, Method for separating liquid mixtures 3, Person making the amendment Case Relationship with Patent applicant address: 2-1-2 Marunouchi, Chiyoda-ku, Tokyo Name (
004) Asahi Glass Co., Ltd. Second Okada Building 6, Number of inventions increased by amendment None 7, Subject of amendment Specification

Claims (1)

[Claims] 1. A method for separating a liquid mixture, which comprises separating a liquid mixture containing at least an organic liquid as one of its constituents by pervaporation using a thin polymer film supported by a reinforcing support.