JPS5888004A - Separation of liquid mixture - Google Patents

Abstract

PURPOSE:To enhance coefficient of separation and a permeation amount per one process, by carrying out vapor separation by using a high molecular membrane comprising a terpolymer constituted from specific components and having a specific ion exchange capacity. CONSTITUTION:In order to separate or concentrate various org. liquid mixtures according to vapor separation, a high molecular membrane, which comprises a terpolymer consisting of a fluorinated olefin compound such as tetrafluoroethylene and different kinds of fluorovinyl ether compounds such as CF2= CFO(CF2)5COOCH3 and CF2=CFO(CF2)COOCH3 or CF2=CFD(CF2)4-COOCH3 and CF2=CFDCF2COOCH3 and has ion exchange capacity of 0.01-3 miliequivalent/ g of dry resin is used. When water/isopropanol or water/ethanol is separated according to vapor separation by this membrane, high coefficient of separation and a high permeation amount are obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for separating a liquid mixture containing at least an organic liquid as one of its components (hereinafter abbreviated as an organic liquid mixture) by pervaporation using a specific polymer membrane. Or related to a method of concentrating.

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.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 transferred 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. It is attracting attention as a new way to do so.

Conventionally, membranes made of polyethylene, polypropylene, cellulose-based polymers, polyacrylonitrile, polyamide, polyester, polystyrene, polytetrafluoroethylene, or copolymers thereof have been known as polymer membranes used in such separation methods. It is being However, when such a membrane is used to separate an organic liquid mixture by pervaporation, the following practical difficulties are observed. That is, (1) Since the concentration ratio (separation coefficient "AB") caused by an organic liquid mixture passing through a polymer membrane once is small, it is necessary to use a very large number of membranes in order to concentrate or separate the organic liquid mixture to the desired concentration. In general, the separation coefficient αAll is as follows: 0 c2) The amount of permeation of an organic liquid mixture through a polymer membrane (generally, the permeation rate per unit membrane surface area, unit membrane thickness, and unit time) (expressed in quantity) is small, so either the surface area of the membrane must be made very large or the thickness of the polymer membrane must be made extremely thin.Therefore, in the former case, the equipment cost becomes excessive.

In the latter case, problems arise in the strength and durability of the membrane.

As the above-mentioned improved process, a method using a polymer membrane in which sulfonic acid groups etc. are bonded to a polymer base, a method using a specific polyamide membrane, a method using an ionomer polymer membrane, etc. are disclosed in Japanese Patent Application Publication No. Disclosed in Japanese Patent No. 52-111888, No. 52-111889, Japanese No. 54-33278, Japanese No. 54-33279, etc., the present inventors have discovered that various organic liquid mixtures can be separated or Various studies have been conducted on means of concentration,
As a result of repeated studies, it was found that a polymer membrane made of a copolymer of two types of combinations of a fluorinated olefin compound such as tetrafluoroethylene and a fluorovinyl ether compound having a carboxylic acid type functional group can overcome the above-mentioned difficulties. This was discovered and completed as the present invention.

That is, the present invention provides a liquid mixture having at least an organic liquid as one of its constituents, which has the general formula CF, =CFO(
A fluorovinyl ether compound (1) represented by CFI )+n-A and the general formula cr, =CFO(CFs
) n-7 fluorovinyl l-thyl compound (
b) and a fluorinated olefin compound (m), separated by pervaporation using a polymer membrane with an ion exchange capacity of 0.01 to 3 meq/g dry resin. The present invention provides a novel method for separating liquid mixtures, which is characterized by a method of separating liquid mixtures.

In the above general formula, m and n are both integers of 1 to 12, and satisfy m −n≧6, ]”=2 to 5, and A and are carboxylic acid type functional groups. And A and I are -COOH, -COO-- or -CN, -Cot, - which can be converted into these groups by hydrolysis.
It is important that the functional group is a carboxylic acid type functional group such as COOR"%-〇〇NR"RI. V is a metal atom such as an alkali metal or alkaline earth metal or bar NR'R'R'R'
% X is the valence number of M, RI is a furkyl group having 1 to 20 carbon atoms, and R'', R'', R', PlR- and R are hydrogen atoms or RI.

The above fluorovinyl ether compound (■) and the fluorovinyl ether compound (■) in the specific terpolymer of the present invention
The compositional ratio of (2) and the fluorinated olefin compound (m) is important because it is related to the ion exchange capacity, which is linked to the performance of the polymer membrane.

Usually, in order to obtain the ion exchange capacity as described below, the amount of the above-mentioned compounds (1) and (II) having a carboxylic acid type functional group in the copolymer is 1 to 50 molt, especially 5 to 50 mol. 40 molti is selected as possible.

Among the total amount of (1) and (■) compounds, (1) and (
The amount of each compound in (1) is related to the mechanical performance such as flexibility and film formability of the polymer membrane, and is also related to the value of m+1 in the above general formula.
The compound (■) (molar ratio) is preferably 0.1 to 5
．． 0, particularly from the range of 0.2 to 2.0.

To explain the present invention in more detail below, the fluorovinyl ether compound (1), which is a monomer compound constituting the polymer membrane of the present invention, has the general formula cr, =c, Fo(cF
, ) mm, and the fluorovinyl ether compound (II) has the general formula CF-CFO(CF2)11-
It is expressed as a person. Here, m + n + m and A' are as described above, but in particular, tll + n is preferably selected from the range of m≧5 and n≦2. Also, A and A'
From the viewpoint of copolymerizability, preferred is -COF. Preferred typical (I)/(II) combinations in the present invention include CFm
=cyo(cy, )s C00CHs and Cchi=CF
O(IJs) COOCHs, C! %=CFO(C
F Yu) 4COOC11m, CF, :CFOC1%C
00CIlsCF, = cro(CP, ), COF and C
F,=++CFOCF,COF%CF warehouse=cro(c+
rs)yco.

Examples include q, and CF, =CFO (CF heavy) proverb cooc-.

These monomers are produced by any known means.

Furthermore, the fluorinated olefin compound (2) is preferably represented by the general formula CF, =CZZ', where 2.zI is -H+'CI+? or -01, and representative examples thereof include tetrafluoroethylene, trifluorochloroethylene, hexafluoropropylene, trifluoroethylene, vinylidene fluoride, vinyl fluoride, and the like. Generally, perfluoroolefin compounds are preferred, and tetrafluoroethylene is particularly preferred.

In producing the above copolymer, the obtained copolymer is modified by using one or more of the above-mentioned compounds and also copolymerizing other monomers. be able to. For example, CF,=CFOCF, (CF, OCF
, ←-CF, ←-^ (A is the same as above l ~ 3 0
〜6 J), CF, ==CνoJ (perfluoroalkyl group having 1 to 10 carbon atoms) can be used in combination to impart further flexibility to the resulting film, or CI', ICF −
CFmCF, , CF, = CF -0(CF, ),
By using a divinyl monomer such as -6-OCF=CF, the resulting copolymer can be crosslinked.

Means for carrying out the copolymerization include peroxy compounds, with or without inert organic or aqueous solvents;
Known means such as carrying out the reaction under the action of a polymerization initiation source such as an azo compound, ultraviolet rays, or ionizing radiation can be employed. For example, Japanese Patent Publication No. 4B-2223, Japanese Patent Publication No. 4B-207
It can be carried out by the method described in Japanese Patent Publication No. 88 and Japanese Patent Publication No. 48-41942. Various methods such as polymerization method % formula % polymerization can be adopted.

The fluorine-containing copolymer of the present invention may be a graft polymer or a block copolymer, but the carboxylic acid type functional group is uniformly dispersed in the copolymer, and the polymer film has a uniform ion exchange capacity. A copolymer obtained by directly copolymerizing each of the above-mentioned monomer compounds is particularly preferred in that it provides the following.

In the present invention, a means for forming a polymer membrane from a fluorine-containing copolymer having a special carboxylic acid type functional group as described above (hereinafter abbreviated as carboxylic acid type fluororesin) may also be used by any known means. , for example, by press molding, roll molding, extrusion molding, solution casting, dispersion molding, powder molding, or the like.

In the present invention, the content of the carboxylic acid type functional group of the carboxylic acid type fluororesin can be adopted over a wide range;
In a preferred embodiment, the ion exchange capacity described below is 0.01.
Selected from a wide range of ~3 meq/g dry resin. The ion exchange capacity is preferably 0.1 to 2.
Approximately 2 milliequivalents/gram dry resin is employed. Also,
From the viewpoint of mechanical strength as a polymer membrane, the molecular weight of carboxylic acid type fluororesin is expressed as TQ value as described below.
The temperature is preferably 50°C or lower, preferably about 70 to 300°C.

In this specification, the term "TQ" is used as follows:
IUi;' is defined. That is, the temperature at which the volumetric flow rate, which is related to the molecular weight of the polymer, is 100 tj/sec is defined as the temperature. In this case, the volumetric flow rate was determined by using a polymer with a -COOCHI group as a carboxylic acid type functional group, and applying the polymer to a diameter of 1 at a constant temperature under a pressure of 30 kg/d.
The amount of polymer melted and flowed out from an oriice with a length of 2n in mb is shown in units of 1/sec. Also,
"Ion exchange capacity" was determined as follows. That is, a carboxylic acid-type fluororesin containing 1000l of carboxylic acid-type functional groups was left in IN HCI at 60°C for 5 hours to completely convert it to H-type, and to make sure that no 1cl remained. Wash thoroughly with water. Thereafter, 0.5 g of this H-type resin was left standing at room temperature for 2 days in a solution prepared by adding 25 rnl of water to 25 ml of 0.1N NaoH. Next, the resin is poured out, and the amount of N and OR in the solution is determined by back titration with 0.1N HCI.

The carboxylic acid-type fluororesin of the present invention may be used, if necessary, during film formation with an olefin polymer such as polyethylene or polypropylene, preferably with an edible fluorine copolymer such as polytetrafluoroethylene or a copolymer of ethylene and tetrafluoroethylene. The copolymer can be blended and molded, and the membrane can be reinforced by supporting the copolymer with a support made of cloth, net, or other woven fabric, nonwoven fabric, or porous film made of these polymers. can. It should be noted that the weight of the resin forming the blend or support is not included in the above ion exchange capacity value.

The polymer film made of carboxylic acid type fluororesin used in the present invention is a non-porous uniform film, and the film thickness is 1 to 25 mm.
0 micron, preferably about 5 to 180 micron. If the film thickness becomes too thin, 1. The strength of the membrane is insufficient or its durability is insufficient. Furthermore, if the membrane is too thick, the amount of permeation of the liquid mixture becomes small, making it impractical. The shape of the polymer membrane is usually a flat membrane, but it can also be used in other shapes such as a cylindrical shape or a hollow fiber shape to increase the surface area. Furthermore, various reinforcing means may be applied, such as embedding a reinforcing material such as a cloth in the membrane, or laminating the membrane on a porous reinforcing body.

The method of the present invention uses the above-mentioned carboxylic acid type fluororesin membrane, -
It is carried out using a device that is divided into a secondary chamber and a secondary chamber.

"-The next chamber contains the organic liquid mixture to be separated or concentrated in liquid form, while the secondary chamber is either evacuated by suitable means or other liquids or gases are circulated. In this way, the organic liquid mixture to be separated or concentrated is The liquid mixture is permeated through a polymer membrane and separated or concentrated by pervaporation.-The liquid inside the next chamber can be circulated externally or internally, or stirred by installing an appropriate stirring device inside the next chamber. It is preferable to hold the specific polymer membrane in an appropriate manner to separate the primary chamber and the secondary chamber, but supporting it with a perforated reinforcing plate may improve durability. Advantageously - the substances that have permeated the polymer membrane from the next chamber are removed from the secondary chamber and collected.Then, usually by means of a suitable heating device, e.g. It is desirable to heat the chamber appropriately.

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. In addition, the pressure range that can be adopted is usually from vacuum to 100 kg/al,
Preferably, the pressure is from vacuum to about 50 to 9/cd; if the pressure is too high, it becomes difficult to maintain the shape of the polymer membrane.

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 due to the presence of azeotropic points, and mixtures of organic substances whose boiling points are close to each other. This is particularly effective in the case of mixtures of organic substances that are difficult to separate by distillation due to their presence. 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, it is necessary that the organic liquid mixture is liquid in its mixed state within the above-mentioned practical temperature range, normal pressure, or within the employed pressure range.

Examples of such organic liquid mixtures include benzene/cyclohexane, benzene/
Mixtures of organic substances such as n-hexane, methanol/acetone, benzene/methanol, acetone/repl:+form; water/isopropanol, water/ethanol,
Water/n-propertool, water/allyl alcohol-methoxyethanol, water/isobutanol, water/n-butanol, water/2-butanol, V-furfuryl alcohol, water/n-pentanol, water/2-pentanol, water/4 Examples include water/alcohol mixtures such as -methyl-1-butanol; water/organic solvent mixtures such as water/tetrahydrofuran, water/dioxane, and water/methyl ethyl ketone.

Mixtures with boiling points close to each other include ethylbenzene/styrene, p-chloroethylbenzene/p
-Chlorstyrene, toluene/methylcyclohexane,
Examples include butadiene/butenes, butadiene/butanes, n-butene/1-butene, and the like. Other examples include water/glycerin, water/glycols, water/propylene chlorohydrin, water/propylene chlorohydrin, water/epichlorohydrin, water/hydrazine, and isomer mixtures.

Furthermore, the method of the present invention can be applied to these mixtures not only in the above two-component systems but also in multi-component systems, such as ternary or more. 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 to the above description.

Example 1.

In a 100 ml stainless steel pressure-resistant reaction vessel, 75 fl of CFO (CFi)a COOCHs, 61 g of CF, = CFO (CF.), COOCH, (charged molar ratio 40/60), and 15 m of 7zobisisobutyro. I added nitrile. After degassing, add 19kl of tetrafluoroethylene at 70°C. /cd and the reaction was carried out.

During the reaction, tetrafluoroethylene was continuously introduced and the pressure was increased to 19
After 7.5 hours of maintaining at J/i, 16 g of copolymer was obtained.

The copolymer was press-molded at 200°C to form a film with a thickness of 100μ, which was then hydrolyzed with caustic soda, treated with pure water at 90°C for 16 hours, and then dried at 70°C for 24 hours. A membrane with an ion exchange capacity of 1.42 maq/g was obtained. Using this layer, a mixed solution of water and isopronoquinol (impropanol/water = 82/18% monitoring ratio) was separated by separation. The separation coefficient of the collected water for isopropanol was 19.6, and the amount of permeation was 527 g/m3·br.

Example 2.

Using the same procedure as in Example 1, CFg=CFO(CFi
)4 COOCHs and CF, =CFOCF,COO
C) & (Preparation molar ratio 45155) and tetrafluoroethylene were copolymerized to obtain an ion exchange capacity of 1.45 meq/
A copolymer of g was obtained.

After the copolymer was hydrolyzed in caustic soda, the functional group was changed to mono-COOH type in hydrochloric acid, treated with pure water at 90°C for 16 hours, and then dried at 70°C for 24 hours. A mixed solution of water and ethanol (ethanol/water = 94/6, weight ratio) was separated by pervaporation using the obtained membrane. The separation coefficient of water for ethanol obtained at 40°C and 10-1 Hg is 5.01, and the amount of permeation is 9.
It was 9 3 9/m2・hr.

Procedural amendment band (text) April Z, 1980 Haruki Shimada, Commissioner of the Patent Office1, Indication of the case 1983 Patent Application No. 1830122, Name of the invention Method for separating liquid mixtures 3, Consideration case for amendment and Relationship Patent applicant address 2-1-2 Marunouchi, Chiyoda-ku, Tokyo Name (
004) Asahi Glass Co., Ltd. 6. Number of inventions increased by amendment None 7. Subject of amendment Specification

Claims (1)

[Claims] A liquid mixture having at least an organic liquid as one of its constituents is defined by the general formula CI%=CFO(CFs)mA
It consists of a terpolymer of a fluorovinyl ether compound (1) represented by the general formula C12=CFO (CIF), a fluorovinyl ether compound (n) represented by n-A', and a fluorinated olefin compound (m). A method for separating a liquid mixture, characterized in that separation is performed by pervaporation using a polymer membrane having an ion exchange capacity of 0.01 to 3 milliequivalents/gram dry resin.However, in the above general formula, m and n are both 1 to 1
It is an integer of 2 and satisfies m −n≧5·11=2 to 5, and A and A′ represent a carboxylic acid type functional group.