JPH03186330A - Separation membrane for osmosis gasification - Google Patents

Abstract

PURPOSE:To obtain the title membrane which has good membrane-forming properties, a high separation factor and large permeation rate by utilizing bis(3- aminophenyl) sulfone and methaphenylene diamine as diamine component and utilizing isophthalic acid as main acid component. CONSTITUTION:30-80mol% bis(3-aminophenyl) sulfone and 70-20mol% methaphenylene diamine are utilized as diamine component. Isophthalic acid is utilized as main acid component. Thereby, a copolymer of aromatic polyamide is obtained from diamine and acid. While the membrane obtained from this polymer maintains a high separation factor without introducing a cross-linked structure and making it a composite membrane, the mixture of organic liquid can be efficiently separated at a high permeation rate by an osmosis gasification method.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for separating water from an aqueous solution of organic substances. 11''Y',L,< refers to minutes #tl?2 for separating water from a water-4f8 liquid mixture by pervaporation.

(Prior art) Conventionally, a water-aqueous liquid mixture or a mixture of two components or more,
Distillation is a well-known method for separating liquid mixtures. However, it is extremely difficult to separate cotton mixtures, near-boiling point mixtures, and compounds that are easily denatured by heat using the distillation method.
Because of the problem that a large amount of energy is often consumed even in the case of mixtures having 4f-capacity, separation technology using membranes is expected to solve these problems. Among separation techniques using membranes, the pervaporation method is considered to be particularly effective for separating water-tF liquid mixtures. This pervaporation method is
By supplying a mixed liquid for the purpose of separation to one side of the polymer membrane, and passing a vacuum, vacuum, or carrier gas to the other side, the vapor n; This is a method of separation by permeation through a membrane.

In other words, pervaporation differs greatly from other membrane separation methods such as reverse osmosis and gas separation in that it causes a phase change across a membrane. Historically, in this method, because the pressure on the permeate side of the membrane is extremely low, the gradient of chemical potential, which is the driving force for the permeation of substances through the membrane, becomes extremely large, making it possible to perform separation in the current concentration range. This is a feature not found in other membrane separation methods. Therefore, reverse osmosis SL: ih
Now, let's move on to operation 11 [I1, which was considered to be difficult in the song of power]
This pervaporation method can also be applied to the separation of organic liquid mixtures. Another character of the pervaporation method, 'f', has traditionally been difficult to separate using distillation methods. The pervaporation method has many features that other separation methods do not have, including the ability to separate liquid mixtures. It is one of the most popular separation methods.

In recent years, research on pervaporation methods in particular has been actively conducted and used. ) There are also many reports regarding molecular membranes.

For example, regarding the separation of water and ethanol, Yoneda Patent No. 2953502 specification i'f uses an acetylcellulose membrane, and US 1kl Patent No. M3035060 specification/F uses a hydrolyzed polyvinyl acetate membrane. It is being proposed. In addition, JP-A No. 59-109204 'fd discloses a composite membrane using a cellulose acetate membrane or a polyvinyl alcohol membrane as skin waste, as disclosed in JP-A-59-5530.
No. 4 and JP-A No. 59-55305 disclose polyethyleneimine-based crosslinked composite membranes, and JP-A No. 61-28113
Publication No. 8 proposes a crosslinked composite membrane based on a polymer containing acrylic acid. Journal of members
rane 5science1 (197G) 271~
In 287, a membrane of polytetrafluoroethylene grafted with poly(N-vinylpyrrolidone) was
rnal of Membrane 5scienceL
(19 old) 191-198, a membrane in which styrene is grafted onto polytetrafluoroethylene is reported. However, in this way, there are many 1'j1 for pervaporation.
Although a dividing membrane has been proposed, this pervaporation method has not been put into practical use.

This is because many of the polymer membranes for pervaporation proposed up to 71: have insufficient separation performance or permeation performance, or have problems with membrane formation v1: or membrane durability. This is caused by

Furthermore, it is said that separation performance and permeation performance are contradictory, and it is difficult to maintain both at a high level. In order to put the permeation membrane into practical use, it is inevitable to solve these problems.In other words, if the separation layer is poor, even if one membrane permeates through the polymer membrane, it will not concentrate to the target pus. Or, it cannot be separated, and as a result, multi-stage separation operations are required, and combinations with other separation methods are required, resulting in larger equipment and excessive equipment costs. In addition, the permeability coefficient of water and A-type compounds permeating through the product Y-membrane (#11 membrane area per unit membrane 1'11 unit (permeation per membrane between 17, 1, 'j; indicated by A) ) is small, it is necessary to make the membrane area very large or to make the membrane thickness extremely lSv<, or to use a composite membrane.
This poses 91 practical problems, such as lowering the strength and durability of the film.

In the present invention, 1 permeation rate means 1 medium, 5IJ-membrane,
(1'/.

WX iTi Ml, jlj, 11′/, I! Between f,
Film thickness 1 pxz 1 kg permeate mixture til
−pxa/t/·hr is expressed as the middle value. In the case of a hollow fiber membrane, it is expressed as 1114☆, membrane area, and amount of permeated mixture per medium tit time. On the other hand, the separation coefficient (α) is the concentration ratio of water and (i) species in the permeate gas to the cilf ratio of water and (i) species in the feed solution. That is, αS = ( X/
P ) p / (X / Y) r. Here, X and Y represent the respective concentrations of water and I1° species in the two-component system, and P and f represent the permeate gas and the feed liquid.

(Problems to be Solved by the Invention) The purpose of the present invention is to solve the problem of water-
1) This machine solves the problem that conventional membranes cannot simultaneously increase the permeation rate and separation coefficient when separating water from a liquid mixture, and provides a polymer membrane with excellent durability. be.

(Means for Solving the Problems) The present inventors have achieved high separation performance and large permeation RL while maintaining favorable membrane formation RL, membrane strength, and membrane performance beyond durability.
As a result of intensive research on the permeation vapor content 111i membrane,
The following separation membranes were found to achieve this objective.

Here, in order to explain the contents of the present invention in detail, tl.
The amount of liquid produced by the permeation method will be explained. That is, it is explained that the liquid separation mechanism by pervaporation iL is based on the dissolution and diffusion of the liquid into the membrane.

・In general, the separation coefficient αn, which is calculated by dividing the concentration ratio of component A to component B after permeation through the membrane by the concentration ratio of component A to component B before permeation, is determined by the ratio of the solubility of component A and component B in the membrane and the inside of the membrane. It is expressed as the product of the ratio of diffusion rates at . In order to increase the separation coefficient αn, it is necessary to reduce either or both of the solubility ratio and the diffusion rate ratio of the A component and the B component.

The solubility is determined by the molecular homology between the permeable molecule and the membrane - using rIH (
'? It is determined by the compatibility rl). Combination of membrane material and separation target'? Solubility parameters have been taken as a measure of physical compatibility. When selecting a membrane material, consider the chemical compatibility between the membrane material and permeable molecules I/1. It is best to choose a substance with a high polarity or a similar membrane material with a polar v1°.If the separation target (permeable molecules) in the feed liquid is hydrophilic, the solubility parameter s + / l: If the high membrane material has a hydrophobic coating, the opposite membrane material is considered to be suitable. In other words, the membrane material used in the previous step is suitable for water-ethanol separation. However, many of these materials dissolve or swell in the feed solution, causing the material to 111. When used alone, problems arise with the durability of the membrane. Therefore, after film formation, durability is often imparted by introducing a crosslinked structure through ionic bonding, electron beam or plasma irradiation, creating a block structure with a non-polar IT material, or forming a composite film. The diffusion rate is determined by the shape, size, and aggregation state of the permeating molecules and the zero peak volume of the membrane. In order to increase the separation coefficient αΩ, the shape of the permeating molecules in the feed liquid must be significantly different. - Molecules with small shapes have a large rate of diffusion and sinking inside the shell. -・way,
The N-mountain volume of a membrane is not defined by the pores in the ia view, but by the molecular gaps seen on a molecular scale. In a membrane with a large Hakusan structure, the difference in the diffusion rate α due to the difference in the size of the permeating molecules is small, and in a membrane with a small zero volume, the difference in the diffusion rate due to the difference in the size of the permeating molecules is large.

In order to increase the separation factor to 1.0 by utilizing the size of permeable molecules, it is safe to reduce the membrane's diameter to 1".

In order to make the crotch rl Il1 body size smaller, use a rack +! A method is being used to form a dense two-dimensional network 11 by introducing structures and cross-sections.

The present inventors have discovered that water-soluble 1114
The separation performance of aqueous solutions containing alcohol, especially alcohol-containing aqueous solutions, was tested using the pervaporagelon method, and the results showed that bis(3-aminophenyl)sulfone and metaphenylenediamine were used as diamine components, and isophthalic acid was used as the isophthalic acid component. -1:,
A copolymer of an acid component and an aromatic polyamide is used as a frame M! 4
Without introducing NX structure or converting to composite membrane? Excellent film forming properties backed by 11 materials and high separation coefficient and permeation rate.
I have found something to do.

The present invention will now be described in detail.

The diamines used in the aromatic polyamide polymer of the present invention are bis(3-aminophenyl)sulfone and metaphenylenediamine as the low molecular weight 4 diamine component. The amount of metaphenylene diamine used is 20 to 70 mol % based on the total gold diamine component of 171.

If it is more than 70 mol%, the solubility of the polymer will be severely reduced, and the solvent conditions for forming the membrane structure into an asymmetric membrane will be strict, making it difficult to obtain a good separation membrane. or,
When the amount is less than 20 mol%, good separation performance cannot be obtained. Separation coefficient and solubility in the range of 20 to 70 mol% of metaphenylenediamine component? It has excellent performance in both functions.

As the acid component, an isophthalic acid component is mainly used, but an aromatic dicarboxylic acid component can also be used. The amount of F used should preferably be 20 mol% or more based on the total acid component.

The polymer is obtained by reacting a diamine with a dicarboxylic acid chloride. As the reaction method, a solution width method or an interfacial gradient method is used. The shape of the separation membrane obtained from the polymer is not particularly limited, such as P-membrane, spiral, or medium thread type, but the membrane should have an asymmetric structure in order to improve the separation performance, especially the permeation rate, li + J, L. is desirable.

The polymer is dissolved in a suitable polar solvent such as N-methylpyrrolidone, NeN'-dimethylformamide or N,N'-dimethylacetamide. In addition, to form an asymmetric structure, a film-forming stock solution in which the polymer is dissolved is cast onto a glass plate using a doctor knife, left for a certain period of time to evaporate a portion of the solvent, and then a part of the solvent such as water is poured onto the glass plate. Polymer-
Just immerse it in Jl solvent. In addition, when forming a fiber membrane, after spinning the film-forming liquid 1 into a medium-sized yarn using spinning 11 gold, part of the solvent was evaporated in -. Then, it may be immersed in a coagulation bath.

When forming an asymmetric structure, a slow coagulating agent such as glycol may be dissolved in the membrane forming stock solution.

The separation membrane prepared in this way can contain 741 substances of water, mixtures such as methanol, ethanol, l-propertool, 2-propertool, alcohols exclusively for n-butanol, acetone, ketones exclusively for methyl ethyl ketone, etc. kind,
An aqueous solution containing one or more compounds consisting of ether compounds such as tetrahydrofuran and dioxane, formic acid and acetic acid, aldehyde lamps such as formaldehyde, acetaldehyde and propionaldehyde, and pyridine and picoline amines. Although it is used for separation by permeation method, it can also be used for separation of a vapor mixture of water and the above-mentioned species by vapor permeation method.

(Function) Since the film obtained from the polymer of the present invention is an aromatic polyamide, it has excellent maturity rating w1;, mulberry resistance, and film formability is also insect repellent. Although the line width of the high separation coefficient and permeation rate exhibited by the protective film is not clear, due to the moderate flexibility and hydrogen bonding in the aromatic polyamide molecules,
It is determined that tfl'M is formed when a molecule-gap (0 mountain volume) suitable for separating water and organic matter is formed. In addition, the aromatic polyamide contains hydrophilic Y1: amide bonds, carboxylic acid pairs, amino J^, etc., and has a strong affinity with water in the feed solution, so the water permeation rate is lower than that of organic matter. This is considered to be because it is larger than the permeation rate.

(Example of Length) The present invention will be simply explained below with a few examples, but the present invention is not limited thereto.

(1) I comparison method 'l'll! In the film forming method No. 2, 3 g of polymer was mixed with 12 g of N.

Dissolved in N'-dimethylacetamide (1) MA C) and cast onto a glass plate using a doctor knife.
After heating and drying at 0°C, the film was peeled off from the glass plate to obtain a homogeneous film. The membrane was sandwiched between filter papers and dried at 160°C for 16 hours in the heating range t). First, heat treatment was performed at 250° C. according to IIl: 11.

In the method for forming the mesoventricular thread membrane, the polymer was dissolved in an N,N' dimethylacetamide solvent so that the polymer concentration was 30% u)%. This solution was extruded with a constant flow Fjt from the spinning material used for making Nakashin yarn, and propylene glycol was extruded with a constant flow of 1 to 2 ell as a core liquid. While removing the air gap and drawing continuously at a constant rate (lom/min), the mixture was introduced into a coagulation tank at 25°C consisting of an aqueous solution containing 30 l'it% of N,N'-dimethylacetamide. Then, it was washed by immersing it in -A# water. Thereafter, it was immersed in isopropyl alcohol and hexane for 1 hour each, and then air-dried overnight. The obtained medium yarn was heated to 160℃,
Reduced by 11. It was dried by heating for 11 minutes.

■Tono permeability (P1: Measuring method of aeration rate) 4-1 constant of aeration rate was measured using a Seikan type permeation measurement device.The supply side of the water/aqueous solution f1° mechanical compound mixture was a popular IF. On the T'1 permeate side, the following pervaporation experiments were carried out with a reduced I of 0.3 or more figs.The feed liquid was added to the membrane surface and stirred at a constant temperature. If
The effective surface was 19.6 cJ. Water passing through the membrane and i1
The organic compounds were collected by condensation with liquid nitrogen.

Add n-propatool as an internal standard to the permeate and T
CI) - The permeation rate and separation coefficient were determined by gas chromatography. Note that the separation coefficient αi of water with respect to ethanol is: ? 811 is defined as follows.

However, X l (Lllllw X lI20
is feed liquid ethanol, water city: +1%, and YN
LOllw Y 112 (l is ethanol of permeate,
Represents 1.1% east of water.

The passing speed (Q) is ・1 in the case of a membrane, Il1 position membrane area surface (
, S1 + '7: Between B and Nf, membrane 1 pm ';j
Permeate mixture: 1 [expressed in kg・unit/J-hr] In the case of inner fabric thread membrane, single membrane area, inner diameter 1'/: [1, ¥
Transmission crowded object between 11 and 11 kg/j hr
Expressed as

Actual h1!1 Example 1 Stirring (1 with ↑ book, temperature system, nitrogen introduction tube and sample input 11)
42.5 g (0.17 J) of bis(3-aminophenyl)sulfone and 7.9 g (0.07 J) of metaphenylenediamine were placed in a four-piece 1-1 flask of No. 9, and a poisonous gas was introduced. Dehydrated N-methylpyrrolidone 500
Add vsQ and go back and forth. After completely dissolving, cool in a water bath until the internal temperature reaches 4°C.

Feeding [from 1, isophthalic acid dichloride powder 49.
Add 5g (0.24+J) and stir while cooling in a water bath for 1 hour. Thereafter, after reacting for 2 hours at a temperature of 40°C, a polypolymer solid of 11 g was obtained in 39 methanol. The polymer was repeatedly pulverized using a mixer and washed with water, and then dried by reduction II: drying. A film of +'V was formed on the obtained polymer according to the self-film forming method, and t
The A permeability 1/1-ability was measured.

The measurement of the external capacity for ventilation is 95, taking into account the durability rL of the membrane.
After supplying % ethanol aqueous solution to the membrane surface, it was heated at 60°C for 10
0 After being left for a while, the pervaporation I/L capacity was measured.
・Do/rl・h).

'Example 2 A hollow fiber membrane was formed from the polymer obtained in the same manner as in Example 1 according to the method described in L, and further heat-treated at the temperature shown in Table 1 for 1 hour. The permeation vaporization t'l capacity of the inner fabric yarn membrane thus obtained was measured.

Measurement of air permeability is 95% considering the durability of the membrane.
After supplying the ethanol aqueous solution to the membrane surface, it was heated to 100 °C at 60 °C.
After standing for a period of time, pervaporation performance was measured.

Table 1 Comparative Example 1 In the same manner as in Example 1, 55.0 g of bis(3-aminophenyl)sulfone (0,22
J) was used as the acid component.

The obtained polymer was formed into a film according to the method described in L, and the pervaporation rl ability was measured. The pervaporation performance was measured by measuring the durability I/I of the membrane at 4 points, supplying a 95% ethanol aqueous solution to the membrane surface, leaving it at 60°C for a long time, and then measuring the pervaporation performance. . Separation coefficient of water and ethanol (α
jj73°) is 53, the permeation rate is 0, 73 (kg-p
xx/♂・h).

Comparative Example 2 In the same manner as Yel, 88.1 g of bis[4-(3-aminophenoxy)phenyl]sulfone (o, rsJ) was used as the diamine component, and 31.9 g of isophthalic acid dichloride was added.
(0.18J) was used as the acid component. The obtained polymer was formed into a film according to the method described in L, and the aeration performance at t and 2 was measured. The pervaporation wL ability was measured by supplying a 95% ethanol aqueous solution to the membrane surface with -IJt durability of the membrane, and then standing at 60° C. for 100 hours, and then measuring the pervaporation performance. The separation coefficient of water and ethanol (α1te8□) is 401, and the permeability is 0.84 (kg-house/ni'-h)
Met.

(Effect of light) If the membrane of the present invention is used, a high separation coefficient can be maintained compared to separation methods using conventional membranes, and a
The machine liquid mixture can be easily separated by pervaporation method. In addition, 11
%, it is possible to form a film using German materials. Therefore, the separation system is made more compact, rationalized, and the processing capacity is increased.
Cost reduction is achieved, and the present invention is effective in practical application of membrane separation methods for shortening the separation process and energy saving in the chemical industry, etc., and the 4-F requirements for industry are extremely large. It is something.

Patent dispatch hole Trade industry? t) ^ Basic industry 1'J length

Claims (1)

[Claims] Bis(3-aminophenyl)sulfone 30 mol% to 80
1. A separation membrane for pervaporation, comprising an aromatic polyamide copolymer containing 70 mol% to 20 mol% of metaphenylenediamine as a diamine component and an isophthalic acid component as a main acid component.