JPS5888003A - 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 with specific concn, of a carboxylic acid type functional group. CONSTITUTION:As a high molecular membrane used in separating and concentrating various org. liquid mixtures according to vapor separation, a copolymer consisting of a fluorinated olefin compound such as tetrafluoroethylene and fluorovinyl ether such as CF2=CFOCF2CF(CF2)O(CF2)3 COOCH3 or CF2= CFO-(CF2)OCF(CF3)COOCH3 is used. When a mixed liquid such as water/isopropanol or water/ethanol is separated according to vapor separation by using said high molecular membrane, high coefficient of separation and a high permeation amount are shown.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for separating or separating liquid mixtures (hereinafter abbreviated as organic liquid mixtures) containing at least an organic liquid as one of their constituents by pervaporation using a specific polymer membrane. This article relates to a method for making deep M.

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 the easily permeable substances 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, polymer membranes used in such separation methods include polyethylene, polypropylene, cellulose-based polymer substances, polyacrylonitrile, polyamide, polyester, and polystyrene.

Membranes made of polytetrafluoroethylene or copolymers thereof are known. however.

When an organic liquid mixture is separated by pervaporation using such a membrane, the following practical difficulties are recognized. That is, (1) the concentration ratio (separation coefficient αAB) caused by the organic liquid mixture passing through the polymer membrane once is small;
In order to concentrate or separate to the desired concentration, it must be passed through an extremely large number of membranes. Generally, the separation coefficient αAB is as follows.

(2) Since the amount of permeation of an organic liquid mixture through a polymer membrane (generally expressed as the amount of permeation per unit membrane surface area, unit membrane thickness, and unit time) is small, the thickness must be 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.

As the above-mentioned improved process, there are 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. It is disclosed in JP-A-52-111888, JP-A-52-111889, JP-A-54-55278, JP-A-54-33279, and the like.

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, a polymer film with a specific carboxylic acid type functional group concentration made of a copolymer of a fluorinated olefin compound such as tetrafluoroethylene and a specific fluorovinyl ether having a carboxylic acid type functional group was found to have a specific carboxylic acid type functional group concentration. We have found that the problem can be overcome.

That is, the present invention provides a liquid mixture having at least an organic liquid as one of its components, a fluorinated olefin compound, and an integer of the general formula %, where E and n are never 0 at the same time, and x
, x', X' are -F or -CFs, A is -CN
, -COF, -COOH, -COOR', -
C004M or -CONfRI, R1 has 1 carbon number
~20 alkyl groups, M Ha metal H Shimata G! -NnI
R"vn', X Gf M ]i valence number, B*
, R), R4, R1, R" and R7 are hydrogen atoms or 1
Using a polymer membrane consisting of a two-component copolymer with a fluorovinyl ether represented by The present invention provides a novel method for separating a liquid mixture, which is characterized by separation by pervaporation.

In the present invention, the specific polymer membrane is composed of
Vinyl ether is a compound represented by the general formula % as described above. In particular, A is a carboxylic acid type functional group, i.e. -COOH, -COO.÷V or -CN, -COF, which can be converted into these groups by hydrolysis.
It is important that it is a functional group such as -COOR' or -CONR"R". M is a metal atom such as an alkali metal or alkaline earth metal or -N84R"R@R1, X is the valence number of M, Hl is an alkyl group having 1 to 20 carbon atoms, R",
VRl, P, R. and R1 are hydrogen atoms or R1.

And, l, m, n, X, X', and X' are as described above.

Among these, preferably l is 0-1, m is 0-5, and n is 0-1. As a preferable specific example, cF, =CF
OCF10F(CF, )OCF, CF, CF,
cooCH,, Crt = CFO (0%) I 0CF
(CFB)COOCH3゜CF2 =CFO(CF,
), 0CF(CF, )COOCH,, CF, =
CFOCPI L? 1l(CF, )oclP, cF
', cot.

CF, =cFoci! , CF(CF, )OCF,
(CF, )COF.

Examples include.

On the other hand, the fluorinated olefin compound used in the present invention preferably has the general formula CF, =CYY' (however, Y
and 7 is -CI, -F or -CF, and representative examples thereof include tetrafluoroethylene,
Examples include chlorotrifluoroethylene, propylene hexafluoride, ethylene trifluoride, vinylidene fluoride, and vinyl fluoride. Among these, perfluoroolefin compounds are preferred, and tetrafluoroethylene is particularly preferred.

In the present invention, the above-mentioned fluorinated olefin compounds and 7-rut It is also possible to use two or more of each of the qvinyl ethers, and in addition to these, other components such as olefin compounds such as ethylene, propylene, and isobutylene, CF, mcFO
Fluorovinyl ethers such as Q (Q represents a perfluorofurkyl group having 1 to 10 carbon atoms), CF, GoF-CF
, :CF, , CF, =cto(cr, ), ~4
Divinyl monomers such as 0CF and FK, as well as functional monomers having a sulfonic acid type functional group and functional monomers other than those mentioned above having a carbonic acid type functional group, can be used in combination. You can also do it.

In the present invention, the content of the calphone enhancing functional group in 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 milliequivalents/gram dry resin! The exchange capacity is preferably 0.1 to 2.
Approximately 2 mm IJ equivalent/gram dry resin is adopted. In addition, from the viewpoint of mechanical strength as a polymer membrane, the molecular weight of the carbonic acid type fluororesin is preferably 50°C or higher, preferably about 70 to 300°C when expressed as the value of T, which will be described later. be.

In this specification, the term rtQJ is defined as follows. That is, the temperature at which the volume flow rate is 100 md/sec, which is related to the molecular weight of the polymer, is defined as TQ. In this case, the volumetric flow rate was determined by using a polymer with a carbonic acid type functional group of 10,000 Hs, and applying the polymer under a pressure of 30 kg/d, at a constant temperature for 1 hour, and for a length of 2 The amount of polymer melted and flowed out from the in orifice is shown in units of -7 seconds. In addition, "ion exchange capacity" was determined as follows. That is, a carboxylic acid-type fluororesin whose carboxylic acid-type functional group is a -Cool group is left in 1N HCI at 60°C for 5 hours to completely convert it to H-type, and then it is thoroughly washed with water so that no MCI remains. Washed. After that, this H-type resin 0.52 was added to 0.1N
NaOH2! It was left standing at room temperature for 2 days in a solution prepared by adding 25 tnl of Sm1K water. Next, the resin is taken out and the concentration of NaOH in the solution is determined by back titration with 0.1N HCI.

In the present invention, the content of the specific fluorovinyl ether in the carboxylic acid type fluororesin is related to the ion exchange capacity of the obtained polymer membrane, so the content in the polymer is usually 1 to 50 molt, preferably It is selected from a range of about 2 to 40 molti. There are various copolymerization methods for producing such copolymers.

For example, known means can be employed, such as carrying out the polymerization under the action of a polymerization initiator such as a peroxy compound, an azo compound, ultraviolet light, or ionizing radiation, with or without the use of an inert organic solvent or an aqueous solvent.

For example, Japanese Patent Publication No. 4B-2223, Japanese Patent Publication No. 48-20
It can be carried out by the method described in Japanese Patent Publication No. 788 and Japanese Patent Publication No. 48-41942. Various polymerization methods such as bulk polymerization, solution polymerization, and suspension polymerization can be employed.

The carboxylic acid type fluororesin of the present invention may be a graft copolymer or a block copolymer, but the point is that the functional groups are uniformly dispersed in the copolymer, and a polymer membrane having a uniform ion exchange capacity can be obtained. Particularly preferred are copolymers obtained by directly copolymerizing the above monomer compounds.

The means for producing a membrane from the carboxylic acid type fluororesin as described above may be carried out by any known means such as press molding, roll molding, extrusion molding, solution casting, disverge run molding or powder molding.

The carbonic acid type fluororesin membrane of the present invention may be formed using an olefin polymer such as polyethylene or polypropylene, preferably polytetrafluoroethylene, or
It can also be molded by blending a fluorine-containing polymer such as a copolymer of ethylene and tetrafluoroethylene, or by using a support made of cloth, net, or other woven fabric, nonwoven fabric, or porous film made of these polymers. Copolymers can be supported to strengthen the membrane.

The polymer membrane made of carboxylic acid type fluororesin used in the present invention is a non-porous, uniform membrane.

The film thickness is 1 to 250 microns, preferably 5 to 180 microns.
The micron level is adopted. If the film thickness becomes too thin,
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 reduced in pressure by a suitable method;
or circulating other liquids or gases. In this way, the organic liquid mixture is permeated through the polymer membrane and separated or concentrated by bar paper evaporation. - 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 permeate 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 approximately ℃.

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 applicable pressure range is normal vacuum to 100 kg/crI,
Preferably, the pressure is from vacuum to about 30'Kg/crl; 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.For example, mixtures of organic substances that cannot be separated by normal distillation methods due to 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. 4IK is effective in cases such as mixtures of organic substances that are extremely 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 needs to 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/cyclohexane and benzene/cyclohexane, which have an azeotropic point.
Mixtures of organic substances such as n-hexane, methanol) V7 setone, benzene/methanol, acetone/repp-form; water/isopropyl, water/ethanol, water/n-p-panol, water/71Jl alcohol, water/
2-methoxyethanol, water/isobutanol, water/n
-Butanol, water/2-butanol, diluted furfuryl alcohol, water/n-pentanol, water/2-pentanol 1. Examples include water/alcohol mixtures such as water/4-methyl-1-7 tar/water; water/organic solvent mixtures such as tetrahydrofuran, water/dioxane, and water/methyl ethyl ketone.

In addition, mixtures with boiling points close to each other include ethylbenzene/styrene, p-chloro-ethylbenzene/
p-Chlorstyrene, toluene/methylcyclohexane, butadiene/butenes, butadiene/butanes, n-
Examples include butene/1-butene. Other examples include water/glycerin, water/glycols, water/propylene chlorohydrin, water/propylene dichlorohydrin, 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.

Processing Example 1 In a 200 m1 stainless steel pressure-resistant reaction vessel, CF =
CFOCF, CF(CF, )O(CFI)SC
00CTo, trichlorotrifluoroethane, and azobisisobutyronitrile as a catalyst were charged. After sufficiently degassing with liquid nitrogen, the reaction vessel was heated to 70°C, and tetrafluoroethylene was charged to carry out copolymerization to obtain a white copolymer.

The copolymer was press-molded at 200°C to form a film with a thickness of 100μ, and then hydrolyzed with a caustic saw I and soaked in pure water at 90°C.
After treatment at 0°C for 16 hours, it was dried at 70°C for 24 hours to obtain a membrane with an ion exchange capacity of 0.95 m·q/l. A mixture of water and inpurpanol (isopropanol/water = 82/1B) was prepared using an iron membrane.
, weight ratio) were separated. Temperature 40℃, permeate side pressure 10-
The separation coefficient for isopro/(nol) of water obtained at
It was m”・hr.

Example 2゜cr, <to(CF, )I 0CF(clF, )C
OOCR, CF, =CFOC% CF (CIPs)
The reaction was carried out under the same conditions as in Example 1, except that O(CF,)sC00CHs was used instead. 20
After hours, a polymer with an ion exchange capacity of 1.15 m5q/f was obtained.

The skeleton polymer was press-molded at 200°C to form a film with a thickness of 100μ. After hydrolyzing the film in a caustic saw, the functional groups were changed to -Cool type in hydrochloric acid, and the film was dissolved in pure water at 9%.
It was treated at 0°C for 16 hours and dried at 70°C for 24 hours. Separate a mixture of water and ethanol (ethanol/water = 94/6, weight ratio) using an iron membrane/by vaporization. The separation coefficient of the water obtained with respect to ethanol at 40° C. and 10 μg was 5.75 (C), and the permeation amount was 753 f/m”hr.

Procedural amendment form) April 1980, Director General of the Patent Office Haruki Shimada 1, Indication of the case 1983 Patent Application No. 183011 2, Name of the invention Method for separating liquid mixtures 3, Person making the amendment Case 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 a fluorinated olefin compound and a compound of the general formula CF* =
CF-()-Crt *CFI OCF, fCF Burnt CFm 0CFX"r. -h (However, l is an integer from 0 to 5, m is 0 to 6, n is an integer from 0 to 4, and l and n are %x will never be 0,
x', x'' are -r or -〇F, A is -CN,
-COF, -COOH, -COOR', -Coo
-YM or -CONII"R", R1 is a furkyl group having 1 to 20 carbon atoms, M is a metal atom or -NR'R
"R"R', X is the valence number of the former, R1, R', R
4, R'', R. and V are hydrogen atoms or Bl), and the ion exchange capacity thereof is 0.
A method for separating a liquid mixture, characterized in that the separation is carried out by pervaporation using a polymer membrane of 01 to 3 milliequivalents/9 dry resin.