JPH0366930B2 - - 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,
A osmosis method that maintains a low vapor pressure by reducing the pressure on the permeate side (secondary side) or by flowing an inert gas, and allows 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 vaporization 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, U.S. 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 that are difficult to separate by distillation, and it is possible to separate isomers with close boiling points (for example, ortho and rose isomers, cis and trans isomers). 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 the permeate / (W A /W _B in the permeate)
W _B ) (in the formula, W _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 is necessary to pass through a large number of membranes. 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 high value that is practical, the separation coefficient α becomes extremely low. The above-mentioned membranes all have a separation coefficient of about 10, and have low separation performance. Therefore, an object of the present invention is to provide a liquid separation membrane for pervaporation that can obtain a high separation coefficient at a high permeation rate when separating water-organic liquid mixtures or organic-organic liquid mixtures by pervaporation. Our goal is to provide the following. [Means for Solving the Problems] In order to achieve the above object, the present inventors have made extensive studies, and surprisingly, they have developed an ionized glycoside skeleton, which has never been used as a separation membrane for pervaporation. The present inventors have discovered that a membrane composed of a polymer in the main chain is a liquid separation membrane having an extremely high separation function, leading to the present invention. In other words, the present invention provides a liquid separation membrane for pervaporation composed of a polymer having a glycoside skeleton as a main chain having a cationic group that forms a salt with a counter anion. It is called a system film). In the present invention, the cationic group includes all cationic groups that can form a salt, but from a practical standpoint, an ammonium group or a metal complex group having a nitrogen atom coordinated to a polyvalent metal ion is preferred. . The ammonium group has the general formula -N ⁺ HnB ₄ -n
(wherein R is a hydrocarbon group having 1 to 6 carbon atoms, n is an integer of 1 to 4), -
NHCH ₂ CH ₂ NH ₂ , −
_{Polyamines such as NHCH2CH2NHCH2CH2NH2 ,}

【formula】

Examples include ammonium groups made from amines having a heterocyclic structure such as [Formula], and groups having a nitrogen atom coordinated to a polyvalent metal ion. A metal complex group formed by coordinate bonding with the general formula

〔Effect of the invention〕

By using the membrane of the present invention, it is possible to efficiently treat a mixed liquid at a high permeation rate while maintaining a higher separation coefficient than in separation methods using conventional membranes. This makes the separation system more compact,
The present invention increases processing capacity and reduces costs, and is effective in practical application of membrane separation methods for shortening separation and purification processes in the chemical industry and saving energy, and has extremely great industrial utility. It is. [Function] By separating an organic liquid mixture by pervaporation using the membrane of the present invention, the mixed liquid can be efficiently treated at a high permeation rate while maintaining a high separation coefficient. is completely unpredictable based on conventional knowledge. The reason for this effect is thought to be that the ionization of the polysaccharide increases its affinity for polar molecules (water, etc.), and at the same time, the ionization causes the polymer molecules to adopt a conformation suitable for separation. It will be done. As mentioned in "Prior Art",
Merely improving affinity through ionization does not improve separation performance, suggesting that fixation of conformation by the glucoside skeleton is important in addition to ionization. [Example] Next, the present invention will be explained in more detail with reference to Examples. Examples 1 to 14 Chitosan membrane with a degree of deacetylation of 98 mol% (thickness 15
~22 μ) in ethanol/water (50/50) containing 1.3 times the mole of polybasic acid based on the amino group of chitosan
Weight ratio) was immersed in the mixed solution at 30°C for 13 hours to obtain a chitosan salt film having an ionic crosslinked structure. The membrane was attached to a pervaporation device with an effective membrane area of 7.0 ^cm2 , and the ethanol/water (50/50 weight ratio) mixture was separated for 60 minutes.
The test was carried out at 0.3 mmHg. Table 1 shows the separation coefficient α and permeation rate Q (Kg/m ² h) 6 hours after the start of pervaporation.

【table】

[Table] Example 15 Chitosan membrane with deacetylation degree of 98 mol% (thickness
17 μ) in ethanol/water (50/50 weight ratio) containing 1.3 times the mole of hydrochloric acid based on the amino group of chitosan.
It was immersed in the mixed solution at 30°C for 13 hours to obtain a chitosan salt film. The membrane was immersed in a dioxane/water (50/50 weight ratio) solution acidified with hydrochloric acid containing 2% formalin for 55 minutes at room temperature to obtain a formal crosslinked chitosan salt membrane. Using this membrane, it was attached to the same pervaporation apparatus as in Example 1, and pervaporation separation of an ethanol/water mixture (50/50 weight ratio) was carried out at 60° C. and 0.3 mmHg. Separation coefficient is 17.92, permeation rate Q is 4.39
Kg/m ² hcm ² heat. Example 16, Comparative Example 1 Chitosan membrane with a degree of deacetylation of 98 mol% (thickness
17μ) in a dioxane solution containing a large excess of pyromellitic anhydride relative to the amino groups of chitosan.
Chitosan crosslinked by amide bonds was obtained by soaking at room temperature for an hour. The crosslinked membrane was diluted with hydrochloric acid at a concentration of 1.5x.
10 ^-3 mol/Kg ethanol/water (50/50 weight ratio)
It was immersed in 200 g of the mixed solution at 30°C for 13 hours to obtain a crosslinked chitosan salt film. The ionized membrane was attached to the same pervaporation device as in Example 1, and ethanol/water (50/50
Weight ratio) Pervaporation separation of mixed liquid at 60℃, 0.3mmHg
I did it at Separation coefficient α is 27.86, permeation rate Q is
It was 4.85Kg/m ² h. As a comparative example, a completely similar experiment was conducted using a non-ionized cross-linked chitosan membrane, and the separation coefficient α was 17.49, and the permeation rate Q was
was 2.87Kg/m ² h. Examples 17-18, Comparative Example 2 Chitosan membrane with a degree of deacetylation of 98 mol% (thickness
17 μ) in ethanol/water (50/
50% by weight) mixture at 30°C for 13 hours to obtain a chitosan salt film. After drying the film for a fixed length at room temperature,
The same pervaporation apparatus as in Example 1 was installed, and pervaporation separation of an ethanol/water (90/10 weight ratio) mixed solution was carried out at 60°C and 0.3 mmHg. Further, as a comparative example, a non-ionized chitosan membrane that had been dried over a fixed length was used and the same operation was carried out. The membrane performance results are also shown in Table 2.

[Table] Examples 19 to 24 Chitosan membrane with a degree of deacetylation of 98 mol% (thickness 15
~20μ) in an ethanol/water (50/50 weight ratio) mixture containing various concentrations of sulfuric acid at 30°C for 13 hours to produce partially ionized chitosan sulfuric acid with different degrees of ionization as shown in Table 3. A salt film was prepared. The membrane was installed in the same pervaporation apparatus as in Example 1, and the pervaporation separation of an ethanol/water (50/50 weight ratio) mixture was carried out at 60° C. and 0.3 mmHg. The membrane performance after 6 hours is shown in Table 3.

[Table] * Mol% of amino groups in chitosan
Examples 25-30 Chitosan membrane with a degree of deacetylation of 98 mol% (thickness 17
~20μ) was immersed at 30°C for 13 hours in a mixed solution of ectanol/water (50/50 weight ratio) containing equimolar sulfuric acid to the amino group of chitosan to obtain a chitosan sulfate film. Using this membrane, it was attached to the same pervaporation apparatus as in Example 1, and ethanol aqueous solutions of various concentrations as shown in Table 4 were permeabilized and separated at 60°C and 0.3 mm.
I did it with Hg. The membrane performance after 6 hours is shown in Table 4.

[Table] Examples 31 to 32 Chitosan membranes (thickness 17 to 20μ) with a degree of deacetylation of 98 mol% and swollen with water were mixed with dioxane solutions (acid anhydrides) containing 10% by weight of acid anhydrides as shown in Table 16. The material was immersed in 200 ml of chitosan salt (existing in large excess relative to the amino groups of the salt) at room temperature for 18 hours to obtain an N-acylated chitosan film. The N-acylated chitosan membrane was heated 1.5x
Ethanol containing sulfuric acid at a concentration of 10 ^-3 mol/Kg/
It was immersed in a water (50/50 weight ratio) mixture at 30°C for 13 hours to obtain a sulfuric acid ionized N-modified chitosan membrane. This ionization membrane was installed in the same pervaporation apparatus as in Example 1, and pervaporation separation of an ethanol/water (50/50 weight ratio) mixed solution was carried out at 60° C. and 0.3 mmHg. 6
The membrane performance after time is shown in Table 5.

[Table] Comparative Examples 3 to 4 The same N-modified chitosan membrane as in Example 31 was attached to the same pervaporation device as in Example 1, and the pervaporation separation of the ethanol/water (50/50 weight ratio) mixture was carried out.
The test was carried out at 60°C and 0.3mmHg. The membrane performance after 6 hours is shown in Table 6.

[Table] Examples 33 to 43 Chitosan manufactured by Tokyo Kasei (degree of deacetylation: 50 mol%) was made into an acetate aqueous solution by a conventional method, dry film was formed from the aqueous solution, and the film was neutralized after film formation. A chitosan membrane with a thickness of 2 to 30μ was attached to the same pervaporation device as in Example 1, and water/ethanol (50/50
Weight ratio) The sulfates of various metals shown in Table 7 were dissolved in the mixed solution at a concentration of 1 x 10 ^-2 mol/Kg, and each was supplied at a temperature of 60°C, and 1 mm
Pervaporative separation was performed with Hg. The separation coefficient and permeation rate were measured 6 hours after starting pervaporation.
After 6 hours, the membrane was removed from the pervaporation device.
The metal ion concentration in the film was determined by atomic absorption spectrometry.
Table 7 shows the appearance of the membrane and the measurement results of metal ion concentration. Comparative example 5

[Table] The same chitosan membrane used in Example 33 was attached to the same pervaporation device as in Example 1, and a water/ethanol (50/50 weight ratio) mixture without any metal salts was heated at a temperature of 60°C. The same operation as in Example 33 was carried out by supplying at ℃. Six hours after starting pervaporation, the separation coefficient α was 9.67, and the permeation rate was 4.57 Kg/m ² h. Examples 44 to 47 The same chitosan membrane used in Example 33 was attached to the same pervaporation device as in Example 1, and various magnesium salts (reagent special grade) were added to the metal ion concentrations shown in Table 8. A mixed solution of water/ethanol (50/50 weight ratio) was supplied at 60° C. and pervaporation was performed at 1 mmHg. Table 8 shows the separation coefficient and permeation rate 6 hours after starting pervaporation.

[Table] Example 48 The same chitosan membrane used in Example 33 was immersed for 13 hours in a water/ethanol (50/50 weight ratio) mixed solution in which cobalt sulfate (special grade reagent) was dissolved. The obtained film is pink and transparent, and the film contains 9.8 mol % of cobalt ions (based on chitosan N atoms), so the obtained film is a chitosan-cobalt complex film. This chitosan-cobalt complex membrane was attached to the same pervaporation apparatus as in Example 1, and permeabilization was carried out at 60° C. and 1 mmHg using a water-ethanol (50/50 weight ratio) mixed solution. Separation coefficient α and permeation rate 6 hours after starting pervaporation are 73.3 and 2.30, respectively.
Kg/m ² h. Example 49 Chitosan membrane with a degree of deacetylation of 99 mol% (film thickness
pervaporation device (effective membrane area 28.3
A water/ethanol (50/50 weight ratio) mixture in which 1.5 × 10 ^-3 mol/Kg of cobalt sulfate was dissolved in cm ² ) was supplied at a temperature of 60°C, and the ethanol concentration was always 50% by weight.
1mmHg on the permeate side using a vacuum pump while maintaining
was aspirated. Table 9 shows the separation coefficient and permeation rate at each concentration when the ethanol concentration of the mixed solution was gradually increased after the separation coefficient reached 844. In addition, when the ethanol concentration was 81.7% by weight, when the temperature of the mixed liquid was lowered to 40℃, the separation coefficient was 3010,
The permeation rate was 0.12Kg/m ² h.

[Table] Example 50 The same chitosan membrane used in Example 33 was attached to the same pervaporation device as in Example 1, and cobalt sulfate heated to 60°C was 1.0×10 ^-2 mol/Kg. Water/t-butanol (50/50
(weight ratio) mixed solution was supplied and pervaporative separation was performed at 60°C and 0.3 mmHg. Separation coefficient α 6 hours after starting pervaporation is 671.2, permeation rate is 1.98 Kg/m ² hr
It was hot. Example 51 The same chitosan membrane used in Example 33 was attached to the same pervaporation device as in Example 1, and cobalt sulfate was dissolved at a concentration of 1.0×10 ^-2 mol/Kg.
A water/acetone (50/50 weight ratio) mixture at 1 mmHg was supplied to carry out pervaporative separation at 1 mmHg. The separation coefficient α 6 hours after starting pervaporation is 234.5.
The permeation rate was 1.81 Kg/m ² h. Examples 52 to 54 After immersing a cellulose membrane (manufactured by UCC) in 1 kg of 25% sodium hydroxide aqueous solution for 24 hours, the cellulose membrane was taken out, excess alkali adhering to the membrane was wiped off with paper, and the alkali cellulose A membrane was obtained. An alkali cellulose membrane was immersed in 500 g of benzene in which 60 g of para-toluenesulfonic acid (tosyl) chloride was dissolved at room temperature for 24 hours to obtain a tosylated cellulose membrane. If the amine used in the amination reaction has a high boiling point (>70°C), the tosylated cellulose membrane is immersed in 200 ml of dimethylformamide in which 20 g of the amine is dissolved at 70°C for 48 hours in a nitrogen atmosphere to carry out the amination reaction. Let's do it. If the amine has a low boiling point (<70°C), place the amine aqueous solution and tosylated cellulose membrane in an autoclave and heat at 50-70°C.
Perform the amination reaction for 48 hours. The obtained aminated cellulose membrane was immersed in 200 g of a 3% aqueous sodium hydroxide solution, and unreacted tosyl groups were hydrolyzed at 70° C. for 2 hours to obtain an aminated cellulose membrane. Example 1 The aminated cellulose membrane with a thickness of 35μ
Cobalt sulfate was added 1.5× to the water/ethanol (50/50 weight ratio) mixture by attaching it to the same pervaporation device.
Each solution was dissolved at a concentration of 10 ^-3 mol/Kg and supplied at a temperature of 60°C, and pervaporative separation was performed at 0.3 mmHg. Table 10 shows the membrane performance 6 hours after starting pervaporation. When the membranes were collected after the pervaporation experiment, all of the membranes shown in Table 10 were colored red, confirming that Co ² -complexes were produced.

【table】

[Table] Examples 55 to 59 Aminated cellulose membranes were treated with a sulfuric acid concentration of 1.5×
10 ^-3 mol/Kg ethanol/water (50/50 weight ratio)
It was immersed in 200 g of the mixed solution at 30° C. for 13 hours to obtain an ionized cellulose derivative salt film. The membrane was attached to the same pervaporation device as in Example 1, and a water/ethanol (50/50 weight ratio) mixed liquid was supplied at 60°C to form a 0.3 mm
Pervaporative separation was performed with Hg. Table 11 shows the membrane performance 6 hours after starting pervaporation.

[Table] Comparative Examples 6 to 10 The same pervaporative separation as in Example 55 was carried out without ionizing the aminated cellulose membrane at all. The results are shown in Table 12.

【table】

Claims (1)

[Scope of Claims] 1. A liquid separation membrane for pervaporation comprising a polymer having a glycoside skeleton as a main chain having a cationic group forming a salt with a counter anion. 2. The liquid separation membrane for pervaporation according to claim 1, wherein the cationic group is an ammonium group or/and a group having a nitrogen atom coordinated to a polyvalent metal ion. 3. The liquid separation membrane for pervaporation according to claim 1 or 2, wherein the polymer is a chitosan salt or a chitosan derivative salt. 4. The liquid separation membrane for pervaporation according to claim 1 or 2, wherein the polymer is a cationic cellulose derivative salt.