JPS61153101A - Separation membrane using curdlan derivative as raw material - Google Patents

Abstract

PURPOSE:To obtain an ultrafiltration membrane having excellent fractional separability in the region of fractional mol.wt., high strength, and good stability by using a curdlan derivative shown by a specified formula and obtained by chemically modifying the hydroxyl group of curdlan as the raw material. CONSTITUTION:A curdlan derivative such as acetyl curdlan shown by the general formula [C6H7O2(OR)X(OH)3-X]n is obtained by alkylating or acylating the hydroxyl group of curdlan (beta-1,3-glucan) shown by the formula. In the general formula, R is a 1-4C lower alkyl group or an acyl group shown by R'CO- (where R' is a 1-4C lower alkyl group), X is 1-3, and (n) shows about 200-2,000 integer. The curdlan derivative is dissolved in formic acid to prepare a cast soln. which is spread over a horizontal glass sheet. The solvent is partially evaporated and the material is dipped into water and gelated to obtain a separation membrane. The membrane is capable of separating org. acids from saccharides having about the same mol.wt.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel ultrafiltration membrane made from a curdlan (β-1,3-glucan) derivative.

In the field of ultrafiltration, various synthetic polymer membranes have been developed over the past ten years, with a molecular weight fractionation of 1 million to 50.
Products with various separation performances up to 0 are commercially available,
It's being used.

Ultrafiltration is commonly used to separate large and medium molecule solutes from small molecule solutes and ions.

Because it is possible to fractionate, separate, concentrate, and purify solutes according to the size of one molecule at the molecular level without applying heat,
It is particularly suitable for separating and concentrating solutes that are sensitive to heat and pH 1 chemicals and have a large gel concentration (e.g. enzymes, proteins, physiologically active substances, etc.).

Pharmaceutical industry 1 Food industry, polymer industry, paint/coating industry,
It is widely used in dairy farming, fisheries, livestock farming, and other fields. In general, the advantages of separation methods using these membranes are (1) low energy consumption, (2) simple equipment and operation, and (3) no phase change (no need to apply heat). ), (4) Continuous operation is possible.

Currently, there are 1 polymer membranes for ultrafiltration in practical use.
For example, polysulfone type, cellulose acetate type,
Examples include vinyl polymer systems and polymer electrolyte complex systems, but it is difficult to say that any of these is still fully satisfactory as an ultrafiltration membrane. For example, in the case of polysulfone-based or polyvinyl alcohol-based membranes, the selectivity of one fraction is poor and it is not possible to perform sharp fractionation according to the difference in molecular weight. Although it is relatively effective for fractionation, it does not show sharp fractionation performance for lower molecular weight solutes.

On the other hand, polyelectrolyte complex membranes are somewhat more amphoteric than those mentioned above due to their molecular weight. However, although this membrane is capable of fractionating solutes with a molecular weight of about 103 to 104, it cannot sufficiently effectively separate solutes with a molecular weight in the range of several hundred to 1,000.

In particular, it is almost impossible to separate substances with a molecular weight of less than 500. Furthermore, a common drawback of each type of polymer electrolyte complex membrane is that the membrane is weak.

In other words, all polymer electrolyte complex membranes are physical.

Chemically weak, easily contaminated, and sensitive to electrolytes.

In view of this situation, the present inventors have conducted extensive research in search of a new material that has excellent molecular weight fractionation, is physically and chemically stable, and is resistant to pollution and electrolytes to form a separation membrane. As a result of repeated efforts, curdlan (β-
A separation membrane obtained from a curdlan derivative obtained by modifying the hydroxyl group of 1,3-glucan) has excellent performance in separating and fractionating solutes and has high strength as a membrane.

The present inventors have discovered that the above object can be fully met and have completed the present invention.

That is, 1 the present invention provides curdlan (β-1
, 3-glucan) obtained by chemically modifying the hydroxyl group of the general formula (1) % formula % (
1) [In the formula, R is a lower alkyl group having 1 to 4 carbon atoms or R'C
It represents an acyl group represented by 0- (wherein R' represents a lower alkyl group having 1 to 4 carbon atoms), and X represents 1 to 3. Further, n represents an integer of about 200 to 2000. ] This is a separation membrane made from a curdlan derivative shown in the following.

In the present invention, the lower alkyl group having 1 to 4 carbon atoms represented by R in the curdlan derivative represented by the above general formula [1] used as a material for the separation membrane 1 includes a methyl group, an ethyl group, an n- Propyl group, is.

-propyl group, n-butyl group, tert-butyl group, etc., and examples of the acyl group represented by R'CO- include acetyl group, propionyl group, butanoyl group, pentanoyl group, etc. Also.

X, which represents the degree of substitution of the modifying group, is usually 1 to 3, but
Preferably it is 2-3. Also, n is usually about 200 to 2
000°, more preferably 300° to 700°.

The curdlan derivative represented by the general formula [1] is usually easily obtained by alkylating or acylating the hydroxyl group of curdlan.

That is, the alkylation of the hydroxyl group of curdlan is performed, for example, according to the conventional method for alkylating the hydroxyl group of polysaccharides. This can be easily carried out using an alkylating agent such as an alkyl compound or a dialkyl sulfate.

Furthermore, acylation of the hydroxyl groups of curdlan can be easily carried out according to conventional methods for acylating the hydroxyl groups of polysaccharides, for example.

For example, in the case of acetylation, curdlan is treated with vinegar a in the presence of a dehydrating agent such as p-toluenesulfonic acid.
Using 1 to 3 times the theoretical amount of acetic anhydride in a solvent,
Between 1 and 5 @ at 40 to 50°C (amount of acetic anhydride depending on the desired degree of substitution).

The reaction temperature, reaction time, etc. are adjusted as appropriate. ) Acetyl curdlan can be easily obtained by carrying out an acetylation reaction, then crystallizing it by pouring it into a large amount of water in a conventional manner, removing P, washing with water, and drying.

The separation membrane of the present invention can be cast into a membrane from a cast solution prepared by dissolving a curdlan derivative in a formic acid solvent, or
The material can be easily produced by a conventional film-forming method, such as casting this onto a porous membrane or support, and then forming a film by a solvent-gelling method. Moreover, it is of course possible to mold it into a hollow fiber shape. The fractional separation properties of the membrane differ depending on the type of solvent used; formic acid alone and water in addition to formic acid.

The molecular weight fractionation is different when methylene dichloride, N,N-dimethylformamide, etc. are mixed, and it is also possible to adjust the molecular weight fractionation by adding an inorganic salt or the like. The molecular weight fractionation property also varies depending on the concentration of the curdlan derivative in the solvent, and also varies depending on the molecular weight, degree of hydrolysis, degree of substitution of substituents, etc. of the curdlan derivative.

The separation membrane of the present invention made from a curdlan derivative has a
It is preferably used for fractionating substances having a molecular weight within the range of about 0 to 20,000, and exhibits excellent fractional separation performance particularly in the region of small molecular weight cutoff (1000 or less).

The separation membrane of the present invention is capable of separating organic acids and sugars that have the same molecular weight, for example, evaporate, glucose and lactic acid, sucrose and malic acid (or tartar, etc.).
, Raffinose (or molasses) and citric acid can be effectively separated. Therefore, in the production of lower organic acids by fermentation of sugars. Separation of organic acids such as liquid mixture of organic acids and sugars.

If the separation membrane of the present invention is used for purification, removal of organic acids contained as impurities in saccharides, etc., this can be carried out extremely effectively.

The separation membrane of the present invention differs from, for example, polymer electrolyte complex membranes in that it has high physical and chemical strength as a membrane, is resistant to pollution, is resistant to electrolytes, and has good stability. It can be used repeatedly and is very easy to use, both from an old-fashioned device and from an operational standpoint.

It is also extremely economical.

As described above, the present invention provides a novel separation method for a novel material that has excellent fractional separation properties, especially in the A region with a small molecular weight cutoff, and has high Ix7 strength and good stability. Since it provides membranes, it is a great contribution to this industry.

Examples and reference examples are shown below, but the present invention is not limited to these examples and reference examples in any way.

In addition, the permeation flux (water flux) in the examples
) is a batch type ultra-filtration device (effective membrane area 1213
4 kl at 20°C using distilled water.
The water permeability was measured under the operating pressure of iF/i and calculated using the following formula.

In addition, the rejection rate is the apparent rejection rate (
From Rj), it is expressed using the true rejection rate obtained by correcting the concentration factor using equation (b).

Here, A represents the concentration ratio (=volume of stock solution [d]/volume of concentrated solution 1 t (ffl/)).

Reference Example 1 308 g (1,85 mol) of curdlan (β-1,3-glucan) and p-toluenesulfonic acid were added to 1.88 liters of acetic acid. ? (0,252 mol) was dissolved.

Add acetic anhydride to this at 45-50°C 1. n 81 (11
, 42 mol) was added dropwise over a period of 1 hour. Dripping amount: 50
After carrying out the acetylation reaction at ℃ for 4 hours, acetic acid 3.64
The solution was diluted with water and filtered with suction. Pour F solution into water 601 to crystallize it, remove the precipitate from F, and wash with water.

Dry to obtain 376 g of acetyl curdlan (yield 72.4
%) was obtained. Acetyl content: 43.4%, viscosity (1,8
%Gam Fluid, 20'C): 12.8 cps.

Reference Example 2゜Acetic acid 1.881, curdlan (β-1,3-glucan) 308 & (1,85 mol) and p-toluenesulfonic acid 48. ! 9 (0,252 mol) was dissolved.

Add to this 1.08 l of anhydrous vinegar at 45-50℃.
(11.42 mol) was added dropwise over a period of 1 hour. After carrying out the acetylation reaction at 1° C. for 1 hour, the mixture was treated in the same manner as in Reference Example 1 to obtain acetylcurdlan 380I. Acetyl content: 44.651 Viscous & (1 g strong formic acid solution, 20°C): 59 cps.

For reference, 113° acetic acid 1.881, curdlan (β-1,3-glucan) 308.9 (1,85 mol) and p-toluenesulfo 71!11' 481 (0,252% mol).

To this, acetic anhydride 1.086 (11,
42 mol) was added dropwise over a period of 2 hours. Dropped amount: 50℃
After carrying out an acetylation reaction for 4 hours, the mixture was diluted with 3.61 parts of acetic acid and filtered with suction. Next, sulfurize M178.
99 and water 1.26% were added and treated at 50°C for 8 hours to partially hydrolyze the acetyl groups.

After the reaction was completed, 60 J of water was added to it for crystallization.

The precipitated crystals are washed with water, dried, and acetyl card: 1F
7 328. ! I got i+. Acetyl content: 37.3%
.

Viscosity (1,8 thiformic acid solution, 20°C): 27 cps.

Example 1゜Reference example 1. 2 parts of the acetyl curdlan synthesized in 1 were dissolved in 11.3 parts of formic acid, and the prepared casting solution was cast onto a horizontally held glass plate to a thickness of 0.2 tgm. was partially evaporated. In the next discussion, 2
A membrane was obtained by immersing it in water at 0°C.

Membrane performance is shown in Table 1.

Table 1 Example 2゜Reference example 1. A casting solution prepared by dissolving 2 parts of the acetyl curdlan synthesized in a mixed solvent of 8.2 parts of formic acid and 1.7 parts of dimethylformamide was poured onto a horizontally held glass plate to a thickness of 0.211 mm. After spreading, the eluate was partially evaporated for 3 minutes at 30°C.

Thereafter, the membrane was immersed in ice water to form a gel, thereby obtaining a separation membrane.

Example 3゜ Reference example 1. 2 parts of acetyl curdlan synthesized in

A casting solution consisting of 8.2 parts of methane dichloride and 3.4 parts of methane dichloride was placed on a horizontally held glass plate at 0.2 w.
After casting to a thickness of i and t, the solvent was partially evaporated at 20° C. for 2 minutes. Then, it was immersed in water at 20°C.

Separation membranes can be obtained by gelation.

Membrane performance is shown in Table 3.

Table 3 Example 4゜Reference example 2. 2 parts of acetyl curdlan synthesized with Gi@
After casting the cast solution prepared by dissolving 18 parts into a thickness of 0.2 u on a horizontally held glass plate,
The solvent was partially evaporated for 5 minutes at 0°C. Next, a separation membrane was obtained by immersing it in water at 20°C.

Membrane performance is shown in Table 4.

Table 4 Authentication example, 5shi1! Reference example 3. 2 parts of acetyl curdlan synthesized in #
The prepared casting solution was cast onto a horizontally held glass plate to a thickness of 9.2 mm.
The solvent was partially evaporated for 1 minute at °C.

Next, the membrane was immersed in water at 20° C. to form a gel, thereby obtaining a separation membrane.

Membrane performance is shown in Table 5.

Table 5 Example 6゜ Reference example 1. 2 parts of acetyl curdlan synthesized in

A casting solution consisting of 8.2 parts of dichloromethane and 3.4 parts of methylene dichloride was placed on a horizontally held glass plate at a thickness of 0.2 mm.
After casting to a thickness of , the solvent was partially evaporated at 20° C. for 2 minutes. Then, it was immersed in water at 20°C.

A separation membrane was obtained by gelation.

The operating pressure of the resulting nine separation membranes is 4 to 9/cd water permeation a
bundle! t 4.261/rrl-hr.

Using this membrane, 11000pp of lactic acid and Ioooppm
of glucose in a 1:1 mixture.

The results are shown in Table 6.

Table 6 However, the degree of separation was calculated according to the following formula.

Example 7゜Reference example 1. 2 parts of the acetyl curdlan synthesized in step 1 were dissolved in 11.3 parts of formic acid, and the prepared casting solution was cast onto a horizontally held glass plate to a thickness of 0.2 mtx, and then heated at 20°C for 4 minutes. The solvent was partially evaporated. Then 2
A separation membrane was obtained by immersing it in water at 0°C.

The permeation flux of water through this separation membrane at an operating pressure of 4 klil/d was 6.61/I·hr.

Using this membrane, 11,000pp of malic acid and 11,000pp of
A 1 part 1 mixture with pp of sucrose was treated.

The results are shown in Table 7.

Table 7 Example 8゜ Reference example 1. 2 parts of acetyl curdlan synthesized in

Cast H solution consisting of 8.2 parts of formic acid and 3.4 parts of methylene dichloride was placed on a horizontally held glass plate at a thickness of 0.2 mm.
After casting to a thickness of , the solvent was partially evaporated at 20° C. for 2 minutes. Next, immerse it in water at 20℃.

A separation membrane was obtained by gelation.

The permeation flux of water at an operating pressure of this separation membrane of 4 kg/d is 4
．． Table 8 shows the rejection rate of various solutes when this membrane was used as an ultrafiltration membrane.

81st meeting white

Claims (1)

[Claims] General formula [1] [C_6] obtained by chemically modifying the hydroxyl group of curdlan (β-1,3-glucan) having the following structure ▲There are mathematical formulas, chemical formulas, tables, etc.▼
H_7O_2(OR)_x(OH)_3_-_x〕_n
[1] [wherein R represents a lower alkyl group having 1 to 4 carbon atoms or an acyl group represented by R'CO- (wherein R' represents a lower alkyl group having 1 to 4 carbon atoms), x is 1
- represents 3. Further, n represents an integer of about 200 to 2000. A separation membrane made from a curdlan derivative shown in ].