JPH0366931B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a liquid separation membrane used for separating water-organic liquid mixtures or organic-organic liquid mixtures by pervaporation. [Prior Art] Conventionally, a liquid mixture to be separated is supplied to the feed liquid side (primary side) of two chambers separated by a separation membrane,
Maintain low vapor pressure by reducing the pressure on the permeate side (secondary side) or flowing inert gas, and allow components with high affinity with the membrane to preferentially permeate into the secondary side as vapor. A method of separating a water-organic liquid mixture by a pervaporation method has been implemented, and various experimental examples have been reported in which a water-organic liquid mixture was separated by such a pervaporation method. For example, US Patent No.
No. 2953502 includes an experimental example of separating azeotropic liquids using cellulose acetate membranes and polyvinyl alcohol membranes, J. Polymer SCI, Symposium No.
41, 145-153 (1973), an experimental example of separating water-methanol mixed liquid in the presence of sodium formate using a cellophane membrane, Journal of Applied
Polymer Science vol. 26 (1981), page 3223, contains an experimental example in which a water-methanol mixed liquid was separated using a grafted polyvinyl alcohol membrane.
Special Publication No. 54-10548, No. 54-10549 and Special Publication No. 59-
No. 49041 reports an experimental example in which a water-organic liquid mixture was separated using a synthetic polymer membrane into which ionic groups were introduced. [Problems to be solved by the invention] Since the pervaporation method does not have concentration limitations due to osmotic pressure like the reverse osmosis method, it is not limited to the separation of liquid mixtures with low concentrations, but can be applied over a wide range of concentrations. It is possible to separate azeotropic mixtures and isomers with close boiling points (e.g., ortho and para isomers, cis and trans isomers) that are difficult to separate using distillation methods. It has the following characteristics. However, the separation membranes used in conventional pervaporation methods have the following problems and are not practical. In other words, the separation rate when a mixed liquid passes through a polymer membrane once [generally, the weight ratio of component A to component B after passing through the membrane is expressed as A before passing through the membrane.
The value divided by the weight ratio of the component to the B component is expressed as a separation coefficient α. That is, α ^A _B = (W _A /W _B ) in permeate / (W A /W _B in non-permeate)
W _B ) (in the formula, _A and W _B indicate the weights of component A and component B, respectively)] are small, so in order to separate or concentrate to the desired concentration, it must be passed through a large number of membranes. In general, the advantages of membrane separation methods cannot be fully utilized, and in particular, the permeation rate through a polymer membrane [generally, the permeation rate per unit membrane surface area and unit time, that is, Q (Kg/m ² hr)] ] becomes a practically high value, the separation number α becomes extremely low. The above-mentioned membranes all have a separation coefficient of about 10, and have low separation performance. Furthermore, one type of membrane cannot handle the treatment of organic liquid mixtures having various concentrations. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a liquid separation membrane for pervaporation that has a high separation coefficient at a high permeation rate and can be applied to the separation of organic liquid mixtures over a wide concentration range. [Means for Solving the Problems] In order to achieve the above object, the present inventors have made extensive studies and surprisingly discovered a glycoside having an anionic group, which has not received much attention as a separation membrane for pervaporation. The inventors have discovered that a membrane crosslinked with polyvalent metal ions and having a system skeleton in its main chain is a liquid separation membrane that can achieve the above object, leading to the present invention. That is, the present invention provides a membrane composed of a polymer having a glycosidic skeleton as a main chain having an anionic group forming a salt with a counter cation, the membrane comprising 9 of the anionic groups. A liquid separation membrane for pervaporation (hereinafter referred to as
It is an anionic polysaccharide membrane). In the present invention, anionic groups include all anionic groups that can form salts, but for practical purposes, sulfuric acid ester residues, sulfonic acid residues, carboxylic acid residues, phosphoric acid ester residues and Phosphonic acid residues are preferably used. These groups may be used alone or in combination of two or more. Specific examples of the anionic polysaccharide membrane of the present invention include salts of natural polysaccharides such as alginic acid, pectic acid, chondroitin sulfate, hyalonic acid, xanthan gum, and derivatives thereof. For example, salts of partially methylesterified alginic acid, carbomethoxylated alginic acid, phosphorylated alginic acid, aminated alginic acid, etc., CM cellulose, cellulose sulfate, cellulose phosphate, sulfoethyl cellulose, phosphoethyl cellulose, phosphorylated guar gum, phosphorylated chitin, etc. Examples include membranes made of semisynthetic polysaccharide salts, etc., which are crosslinked by bonding anionic groups with polyvalent metal ions. In particular, in the present invention, a membrane consisting of an alginate, an alginic acid derivative salt, and a cellulose derivative salt,
Membranes that are crosslinked by bonding anion-resistant groups with polyvalent metal ions have excellent film formability, mechanical strength,
This is a preferable membrane in terms of membrane performance. Alginic acid is a sticky polyuronic acid extracted from brown algae such as kelp.
This is a block copolymer consisting of three types of blocks: a GG block in which only L-guluronic acid (G) of the (1→4) bond is arranged, and an MG block in which M and G are arranged alternately. Alginic acid forms a salt with an alkali such as sodium hydroxide or potassium hydroxide and easily dissolves in water. Therefore, by casting a solution of this alginate on a glass plate and drying it naturally, it becomes transparent. A homogeneous alginate film is formed. Alternatively, the alginate solution may be dissolved in a water-soluble organic solvent (e.g. ethanol, isopropanol,
When brought into contact with acetone, etc.) or a concentrated salt solution, the salt has the property of coagulating and precipitating, so a wet coagulation film can also be made using this property. Alginic acid polysaccharide refers to alginic acid and its derivatives. 9 to 70 mol% of the anionic groups of the alginate polysaccharide membrane are combined with polyvalent metal ions,
By crosslinking, the membrane of the present invention can be obtained. In addition, carboxymethyl cellulose, which is an anionic cellulose derivative salt, can be obtained by reacting chloroacetic acid with cellulose under alkaline conditions, and cellulose sulfate can be obtained by reacting chlorosulfonic acid with cellulose.
It can be easily obtained by reacting a pyridine mixture with cellulose. The membrane of the present invention can be obtained by similarly bonding 9 to 70 mol % of the anionic groups with polyvalent metal ions and crosslinking these membranes. The liquid separation membrane of the present invention is:
The membrane is crosslinked by bonding the anionic groups of the membrane mainly composed of the above-mentioned anionic ionizable polysaccharide polymer with polyvalent metal ions, but polymers compatible with the polysaccharide, such as PVA and pullulan, , blended membranes with neutral polysaccharides such as starch, and membranes in which grafted membranes grafted with hydrophilic vinyl monomers such as acrylic acid are similarly crosslinked with polyvalent metal ions. Furthermore, in the present invention, a small amount of cation may be contained within the same polymer without departing from the spirit of the present invention. As described above, in the anionic polysaccharide membrane of the present invention, 9 to 70 mol% of the anionic groups must be crosslinked by bonding with a polyvalent metal. If the crosslinking ratio, that is, the crosslinking rate, is less than 9 mol%, the water resistance and mechanical strength will be insufficient and the effects of the present invention will not be exhibited. In addition, the crosslinking rate is 70 mol%
If it is larger than , the permeation rate tends to be low. Polyvalent metal ions used for such crosslinking include alkaline earth metals, transition metals, periodic table 3B,
It is effective and preferred in the present invention to use at least one small polyvalent metal ion of metals belonging to group 4B. Examples of alkaline earth metals include calcium, strontium, barium, etc.
Examples of transition metals include titanium, chromium, manganese, iron, cobalt, nickel, copper, zinc, zirconium, europium, cerium, rhodium, etc.
Examples of metals belonging to Groups 3B and 4B of the periodic table include aluminum, tin, and the like. Anionic polysaccharide membranes are hydrophilic, so water-
When separating organic liquid mixtures, membrane performance is greatly affected by the water concentration of the liquid mixture to be separated, but as mentioned above, the 9 to 70% of anionic groups in the membrane
Bonding mol % with polyvalent metal ions and crosslinking improves water resistance and mechanical strength, thus expanding the applicable concentration range of organic liquid mixtures compared to non-crosslinked membranes. In other words, in the conventional method, it was necessary to select an appropriate membrane depending on the concentration of the organic liquid mixture, but with the membrane of the present invention, one
Organic liquid mixtures of various concentrations can be treated with high permeation rates while maintaining high separation coefficients with only different types of membranes. For example, in the case of an alginate membrane, the crosslinking rate in the present invention is the ratio (mol %) of carboxyl groups ionically bonded to crosslinking metal ions to all carboxyl groups of alginic acid. In calculating the crosslinking rate, the amount of crosslinked metal ions was determined by atomic absorption spectrometry, and it was assumed that the carboxyl group of alginic acid was stoichiometrically ionic bonded to the metal ion. The same applies to other anionic polysaccharide membranes. In order to improve the water resistance and mechanical strength of anionic polysaccharide membranes, it is necessary to crosslink them by bonding with polyvalent metal ions as described above.
In addition to using the above-mentioned metal ions, such crosslinking methods include forming ester bonds between polysaccharide molecules using organic polybasic acids or polyhydric alcohols, and forming acetal bonds between molecules using aldehydes, etc. There are methods. Such crosslinking methods may be used alone or in combination, or may be used in combination with the method using polyvalent metal ions described above. The ionization method, crosslinking method, etc. described above can also be applied to other anionic polysaccharides. Whether or not a film is crosslinked with metal ions can be determined quantitatively using the above-mentioned atomic absorption spectrometry method, but it can also be confirmed by observing the coloring characteristic of salts. The method of crosslinking the anionic polysaccharide membrane with the above polyvalent metal ions is not particularly limited, but may include immersing the anionic polysaccharide membrane in a solution containing the metal ions, or a mixture containing the metal ions. A method of permeating vaporization using a liquid may be used. Furthermore, after crosslinking the membrane as described above, it is possible to further improve the separation coefficient in the separation of water-organic liquid mixtures by drying the membrane before pervaporation. Water-organic liquid mixtures that can be separated by the pervaporation separation membrane of the present invention include water/methanol, water/ethanol, water/n-propanol,
water/isopropanol, water/n-butanol,
Water/isobutanol, water/n-amyl alcohol, water/n-hexanol, water/2-ethylhexanol, water/n-octanol, water/ethylene glycol, water/1,3-propanediol,
Water-alcohol mixtures such as water/1,4-butanediol, water/1,2-propylene glycol, water/glycerin; water/tetrahydrofuran,
Water/dioxane, water/methyl ethyl ketone, water/
Acetone, water/N,N-dimethylacetamide,
Water/N,N-dimethylformamide, etc. are mentioned. In addition, organic-organic liquid mixtures include methyl acetate/methyl alcohol, ethyl acetate/ethyl alcohol, benzene/cyclohexane, methanol/acetone, benzene/methanol, benzene/ethanol, acetone/chloroform, methanol/acetone, ethylbenzene/styrene,
Examples include parachloroethylbenzene/parachlorostyrene, toluene/methylcyclohexane, and the like. The anionic polysaccharide-based membrane of the present invention is a water-organic liquid mixture, or in the case of an organic-organic liquid mixture,
Polar organic liquids (e.g. alcohols, ketones, etc.)
It is particularly effective in separating mixtures containing The thickness of the separation membrane of the present invention is 1μ to 300μ, preferably 5 to 200μ. If the film thickness is thinner than this, the strength of the film will be insufficient or the durability will be insufficient. Furthermore, if the membrane thickness is thicker than this, the amount of liquid mixture permeating through the membrane will be small, making it impractical. Furthermore, when the ionized polysaccharide membrane is used by being attached to a support membrane, such as a microporous membrane, the ionized polysaccharide membrane can be sufficiently used even if the thickness of the ionized polysaccharide membrane is reduced. In this case, the thickness of the ionized polysaccharide membrane can be reduced to about 0.1 μm. The shape of the separation membrane is used as a flat membrane (flat membrane), but it can also be used in other shapes such as a cylindrical shape or a hollow fiber shape to increase the membrane surface area. The pervaporation device used in the present invention is not particularly limited, and any conventionally known device can be used, and such a device can be operated under conventional conditions to separate the organic mixed liquid. In performing pervaporation, the larger the pressure difference between the feed liquid side and the permeate side, the more effective it is, but for industrial implementation it is preferable to provide a pressure difference of 0.5 to 1 atmosphere. The pressure on the feed liquid side is preferably at or near atmospheric pressure, and the pressure on the permeate side is preferably maintained at a reduced pressure below the vapor pressure of the permeate component. Methods for maintaining the permeate side at reduced pressure include drawing a vacuum to reduce the pressure, or flowing a gas that does not react with the constituent components to maintain a low vapor pressure. Separation temperature is 40℃
The temperature above and below the azeotropic temperature of the organic liquid mixture to be separated is normal, but is not particularly limited. One ionized polysaccharide-based membrane is used to separate liquid mixtures.
If the desired concentration cannot be obtained by passing the sample multiple times, it is possible to concentrate and separate the sample to the desired concentration by installing a similar device in succession and passing the sample multiple times, or by combining it with distillation. [Effects of the Invention] By using the membrane of the present invention, organic liquid mixtures with a wide concentration range can be separated at a high permeation rate while maintaining a higher separation coefficient than separation methods using conventional membranes.
It can be processed efficiently with one membrane. For this reason, the separation system has been made more compact, rationalized, increased throughput, and lowered in cost, and the present invention is effective in practical application of membrane separation methods for shortening separation and purification processes in the chemical industry and saving energy. Therefore, it has extremely great industrial utility. [Function] The membrane of the present invention has a large separation coefficient and is excellent in water resistance and mechanical strength. By separating a liquid mixture by pervaporation using the membrane of the present invention, a high separation coefficient can be maintained. However, although it is possible to efficiently process with a high permeation rate, such an effect is completely unpredictable from conventional knowledge. The reasons for this effect are that the polymer molecules adopt a conformation suitable for separation, that their affinity with polar molecules (water, etc.) increases, and that anionic groups are combined with polyvalent metal ions in a specific amount. combine,
This is thought to be due to improved water resistance, mechanical strength, and stability due to crosslinking. [Example] Next, the present invention will be explained in more detail with reference to Examples. Examples 1 to 3 Sodium alginate (manufactured by Hani Chemical, 1000cps)
A 1% by weight aqueous solution was prepared, which was cast onto a glass plate and air-dried to obtain a homogeneous transparent sodium alginate film with a thickness of 20 to 25 μm. Pervaporation device equipped with the membrane (effective membrane area 7.0
cm ² ) with sulfates of various metals shown in Table 1 dissolved in a water/ethanol (50/50 weight ratio) mixture to a concentration of 1 x 10 ^-2 mol/Kg. Each was supplied at a temperature of 60°C, and while the ethanol concentration was always maintained at 50% by weight, the permeate side was sucked to 0.3 mmHg using a vacuum pump. After condensing the vapor that passed through the membrane, the amount of permeation was measured.
The component composition was analyzed using a gas chromatograph.
Separation coefficient, permeation rate, and membrane exchange metal crosslinking rate (mol) 6 hours after starting pervaporation for water/ethanol mixed liquids containing various metal ions
%) are shown in Table 1.

[Table] Examples 4 to 7 The same sodium alginate membrane as used in Example 1 was immersed in a water/ethanol (50/50 weight ratio) mixed solution in which various metal salts shown in Table 2 were dissolved. After the sodium ions in the sodium alginate membrane were exchanged with these metal ions, the membrane was placed in the same pervaporation apparatus as in Example 1 and treated with metal ion-free water/ethanol (50/50 weight ratio).
The same operation as in Example 1 was carried out by supplying the mixed solution. Separation coefficient, permeation rate, and crosslinking rate of exchanged metal ions (mol) of the membrane 6 hours after starting pervaporation
%) are shown in Table 2.

[Table] Examples 8 to 24 The same sodium alginate membrane used in Example 1 was treated with various metal ions as shown in Table 3.
It was immersed in a water/ethanol (50/50 weight ratio) mixture dissolved at a concentration of 1.5×10 ^-3 mol/Kg (30°C,
17 hours), after exchanging the sodium ions in the sodium alginate membrane with these metal ions,
The membrane was installed in the same pervaporation apparatus as in Example 1, a water/ethanol (50/50 weight ratio) mixture containing no ions was supplied, and the same operations as in Example 1 were carried out. Table 3 shows the separation coefficient and permeation rate 6 hours after starting pervaporation.

【table】

[Table] Examples 25 to 31 The same sodium alginate membrane used in Example 1 was coated with various nickel salts (nickel concentration 1.5×
10 ^-3 mol/Kg) dissolved in water/ethanol (50/50 weight ratio) mixture (30℃,
After exchanging the sodium ions in the sodium alginate membrane (17 hours), the membrane was attached to the same pervaporation apparatus as in Example 1, and water/ethanol (50/50
(weight ratio) was separated at 60°C and 0.3 mmHg. Separation coefficient 6 hours after starting pervaporation,
The transmission coefficients are shown in Table 4.

[Table] Examples 32 to 37 The same sodium alginate membrane used in Example 1 was mixed with a water/ethanol (50/50 weight ratio) mixed liquid (cobalt concentration) in which cobalt sulfate was dissolved.
1.5×10 ^-3 mol/Kg) (30°C, 17 hours) to exchange sodium ions in the sodium alginate membrane, this membrane was installed in the same pervaporation apparatus as in Example 1 and the results are shown in Table 5. Separation of various water/ethanol mixtures was carried out at 60°C and 0.3 mmHg. Table 5 shows the separation coefficient and permeation rate 6 hours after starting pervaporation. The crosslinking rate of the exchanged metal was 53.0 mol%.

[Table] Examples 38 to 41 The cobalt-exchanged sodium alginate membrane obtained in the same manner as in Example 33 was attached to the same pervaporation device as in Example 1, and various water/organic mixed liquids (organic liquid concentration 50 wt%) were used. Separation was performed at 60°C and 0.3 mmHg. Table 6 shows the separation coefficient and permeation rate 6 hours after starting pervaporation. In either case, water preferentially permeates.

[Table] Examples 42 to 46 Alginic acid (manufactured by Hanui Chemical Co., Ltd.) was made into a 5% by weight water slurry, and K, NH ₄ ,
An alkaline aqueous solution of Li (5 to 25% by weight) was added to obtain various alginate aqueous solutions. Pour this aqueous solution into absolute ethanol to precipitate the alginate,
Excess amount of alkali was washed and removed to obtain various fibrous alginates shown in Table 7. The various alginates were made into 3% by weight aqueous solutions, cast on glass plates, and air-dried to obtain various homogeneous and transparent alginate films with a thickness of 20 to 25 μm. The membrane was exchanged with various metal ions as shown in Table 7 in the same manner as in Example 8. The metal ion exchange membrane was installed in the same pervaporation device as in Example 1, and
Ethanol-water (50/50 weight ratio) at ℃, 0.3 mmHg
The mixed liquid was separated by pervaporation. Table 7 shows the separation coefficient and permeation rate 6 hours after starting pervaporation.

[Table] Examples 47-48 Film thickness 20-25 μm formed by the same method as Example 1
The sodium alginate membrane was immersed in an ethanol aqueous solution of 3% by weight hydrochloric acid (ethanol concentration 50% by weight) at room temperature for 24 hours to obtain an alginic acid membrane. The membrane was subjected to metal ion exchange using cobalt sulfate or strontium chloride in the same manner as in Example 8. The metal ion exchange membrane was installed in the same apparatus as in Example 1, and an ethanol/water (50/50 weight ratio) mixed solution was used for 60 min.
Pervaporative separation was performed at °C and 0.3 mmHg. Table 8 shows the separation coefficient and permeation rate 6 hours after starting pervaporation.

[Table] Comparative Example 1 The same sodium alginate membrane used in Example 1 was attached to the same pervaporation device as in Example 1,
When a water/ethanol mixed liquid containing no metal ions (ethanol concentration 50 wt%) was supplied at a temperature of 60°C and the same operation as in Example 1 was carried out, the membrane melted and burst, making it impossible to measure the performance. . Comparative example 2 Sodium alginate (manufactured by Hani Chemical, 1000cps)
60 g was added to 2% by weight aqueous hydrochloric acid solution 1 and stirred at room temperature for 1 hour. The precipitated alginic acid was separated, and this washing operation with diluted hydrochloric acid was repeated three times. After separation, the alginic acid was washed with cold distilled water until the water became neutral, and finally washed with ethanol and air-dried to obtain 47 g of purified alginic acid.
10 g of the purified alginic acid was added to 200 ml of an aqueous solution containing 1.2 times the amount of sodium hydroxide per carboxyl group of alginic acid, and the mixture was heated to 50° C. to dissolve the alginic acid. After complete dissolution, this solution was poured into absolute ethanol to precipitate fibrous sodium alginate. The precipitated sodium alginate was washed three times with 1 portion of ethanol to remove excess sodium hydroxide, yielding 10.9 g of purified sodium alginate. Purified sodium alginate 5
% by weight aqueous solution, cast it on a glass plate, and let it dry naturally to form a homogeneous transparent product with a thickness of 15% by weight.
Purified sodium alginate membranes of ~25μ were obtained. A dry film (thickness 17μ) of purified sodium alginate was soaked in ethanol/water (50/50) containing 2% by weight of hydrochloric acid.
weight ratio) mixture at room temperature for 2 hours to form an alginic acid (carboxylic acid) film (sodium content 0.01 mol).
%) was obtained. The membrane was attached to the same pervaporation separation device as in Example 1, and pervaporation separation of an ethanol/water (90/10 weight ratio) mixed liquid was carried out at 60°C and 0.3 mmHg, and the separation coefficient after 6 hours was and the permeation rate were 10.32 and 1.87 Kg/m ² ·hr, respectively. Example 49 Sodium chondroitin sulfate (manufactured by Wako Pure Chemical Industries)
A 5% by weight aqueous solution of was cast on a glass plate and air-dried to obtain a dry film (thickness: 37μ) of sodium chondroitin sulfate. The membrane was attached to the same pervaporation device as in Example 1, and calcium chloride 1.5×
Ethanol/water containing 10 ^-3 mol/Kg (90/
Pervaporative separation was carried out in the same manner as in Example 1 using the mixed solution (weight ratio: 10). The separation coefficient after 6 hours is
3012, the permeation rate was 0.17Kg/m ² ·hr. Example 50 15g of cellulose powder in isopropanol
30% by weight of sodium hydroxide was added, followed by 50 ml of isopropanol in which 15.5 g of monochloroic acid had been dissolved. After reacting at 60°C for 4 hours, the solid was washed several times with water-containing methanol to obtain sodium salt of carboxymethyl cellulose. This sodium salt has a concentration of 5% by weight.
Dissolved in water and cast on a glass plate,
By air drying, a carboxymethyl cellulose sodium salt film (thickness: 20 μm) was obtained. Using this membrane, pervaporative separation was carried out in the same manner as in Example 1 using a mixed solution of ethanol/water (90/10 weight ratio) containing 1.0×10 ⁻³ mol/Kg of calcium chloride. The separation coefficient and permeation rate after 6 hours are respectively
228.3, 40.1 g/m ² ·hr. Example 51 1wt% sodium alginate (manufactured by Hanui Chemical,
300 cps) and 5 parts by weight of 1 wt% polyvinyl alcohol (PVA117, manufactured by Kuraray Co., Ltd.) were mixed, cast on a glass plate, and air-dried to obtain a PVA blend film. The PVA-blended sodium alginate membrane was immersed in ethanol/water (50/50%) containing _CoSO4 .
50% by weight) mixture (Co ²⁺ contains 0.5 equivalents relative to the carboxyl group of alginic acid) at 30°C overnight to crosslink with cobalt ions. the membrane
After immersing in 93wt% ethanol aqueous solution for 1 minute,
It was installed in the same pervaporation device as in Example 1, and heated at 60℃.
After supplying 93wt% ethanol aqueous solution for 5 minutes,
Pervaporative separation was performed with the secondary side set to 0.3 mmHg.
The separation coefficient and permeation rate 6 hours after starting pervaporation were 5030 and 119 g/m ² ·hr, respectively.
Further, the crosslinking rate of Co ²⁺ in the film was 25.1 mol%. Example 52 and Comparative Example 3 The same sodium alginate membrane as in Example 1 was prepared using a mixed solution of ethanol/water (50/50 weight ratio) containing cobalt sulfate (Co ²⁺ is contained in an amount of 0.5 equivalent to the carboxyl group of alginic acid). Soak overnight at 30℃,
Crosslinked with cobalt ions. 93wt% of the film
After immersion in an ethanol aqueous solution for 1 minute, Example 1
It was attached to the same pervaporation device as the one, and after supplying a 93wt% ethanol aqueous solution at 60℃ for 5 minutes, the secondary side was
Pervaporative separation was performed at 0.3 mmHg. The separation coefficient and permeation rate 6 hours after starting pervaporation were 78,700 and 97 g/m ² ·hr, respectively. Also, the separation coefficient and permeation rate after 120 hours were 51,600 and 51,600, respectively.
The separation coefficient and permeation rate were 65.6% and 55.5% of the ^initial values, respectively.
Further, the crosslinking rate of Co ²⁺ in the membrane was 25.8 mol% (Example 52). The same sodium alginate membrane as in Example 1 was treated with ion-free ethanol/water (50/50 weight ratio).
It was immersed in the mixed solution at 30°C overnight. After immersing the membrane in a 93wt% ethanol aqueous solution for 1 minute, it was attached to the same pervaporation device as in Example 1, and after supplying a 93wt% ethanol aqueous solution at 60°C for 5 minutes, the secondary side was immersed at 0.3
Pervaporative separation was performed at mmHg. The separation coefficient and permeation rate 6 hours after starting pervaporation were 118,800 and 96.2 g/m ² ·hr, respectively.
Also, the separation coefficient and permeation rate after 120 hours are 53800 and 40.3g/m ² hr, respectively, which are different from the initial values of separation coefficient and permeation rate, respectively.
They are 45.3% and 41.9% (Comparative Example 3). Comparative Example 4 Ethanol/water containing cobalt sulfate (50/
Pervaporative separation was performed in the same manner as in Example 52, except that the sample was immersed overnight at 30°C in a mixed solution (Co ²⁺ containing 5.0 equivalents relative to the carboxyl group of alginic acid) (weight ratio: 50% by weight). The crosslinking rate of Co ²⁺ in the film was 100 mol%. The separation coefficient and permeation rate 6 hours after starting pervaporation were 2058 and 90 g/m ² ·hr, respectively. Example 53 and Comparative Examples 5 to 6 A sodium alginate membrane crosslinked with the same cobalt ions as in Example 1 was placed in the same pervaporation device as in Example 1, and then ethanol/water (70/30 weight ratio) was mixed at 60°C. Pervaporative separation was performed by supplying liquid and setting the secondary side of the membrane to 0.3 mmHg. The separation coefficient and permeation rate 6 hours after starting pervaporation are 1449, respectively.
and 2020 g/m ² ·hr (Example 53). After installing a sodium alginate membrane that was not crosslinked with metal ions in the same pervaporation device as in Example 1, a 60°C ethanol/water (70/30 weight ratio) mixed solution was supplied to one side of the membrane for 5 minutes. , the secondary side
When the temperature was set to 0.3 mmHg, the membrane ruptured and measurement could not be performed (Comparative Example 5). Moreover, the same result was obtained even when a mixture of ethanol/water (80/20 weight ratio) was used (Comparative Example 6).

Claims (1)

[Scope of Claims] 1. A membrane composed of a polymer having a glycoside skeleton as a main chain having an anionic group forming a salt with a countercation, the membrane comprising a polymer having an anionic group forming a salt with a counter cation. A liquid separation membrane for pervaporation, characterized in that 9 to 70 mol% of the membrane is crosslinked by bonding with polyvalent metal ions. 2. The penetrant according to claim 1, wherein the anionic group is at least one group selected from a sulfuric acid ester residue, a sulfonic acid residue, a carboxylic acid residue, a phosphoric acid ester residue, and a phosphonic acid residue. Liquid separation membrane for vaporization. 3. The liquid separation membrane for pervaporation according to claim 1 or 2, wherein the polymer is an alginate or an alginic acid derivative salt. 4. The liquid separation membrane for pervaporation according to claim 1 or 2, wherein the polymer is an anionic cellulose derivative salt. 5. Claim 1, wherein the polyvalent metal ion is an ion of at least one kind of alkaline earth metals, transition metals, and metals belonging to Groups 3B and 4B of the Periodic Table.
The liquid separation membrane for pervaporation according to item 2, item 3, or item 4.