JP3505735B2 - Decolorization method - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for decolorizing various solutions. More specifically, the present invention relates to a method of adsorbing and removing a coloring component in a liquid by contacting an adsorbent with an amino acid or other fermentation liquid containing a coloring component, a fruit juice, a sugar juice, or the like.

[0002]

2. Description of the Related Art Conventionally, glucose, cane sugar, beet sugar,
For decolorization of sugar solutions such as starch sugar, amino acids, fruit juices, and organic acids, decolorization performance (decolorization treatment amount, decolorization rate,
From the viewpoints of desorption rate, etc.), chemical stability, strength and price, styrene-based anion exchange resins are widely used. Typical examples of such anion exchange resin include DIAION SA11A (DIAION is a registered trademark of Mitsubishi Kasei Co., Ltd.) which is a gel type resin and DIAION PA308 which is a porous resin. These have a trimethylammonium group as an exchange group. As a similar anion exchange resin, Amberlite IRA-40
0 (Amber Light is a registered trademark of Rohm & Haas),
There are IRA-410 and the like. Further, DIAION WA30, which is a styrene-based weakly basic anion exchange resin having a dimethylamino group, is also widely used for the same purpose. Decolorization methods using these styrene resins are described in JP-A-50-77552, 51-22834, JP-A-3-112500, and JP-B-56-1080, 60-.
998 and the like. Other than styrene resin,
Amberlite IRA-458, which is an acrylate-based strongly basic anion exchange resin, is also used for decolorization.

[0003]

The use of a styrene type anion exchange resin for decolorization has the following problems. (1) Since the portion other than the ion exchange group occupies a large portion of the resin weight, the ion exchange capacity is small. (2) The benzyl group in the resin is a highly hydrophobic group,
Due to the hydrophobic interaction of the benzyl group, organic substances are nonspecifically adsorbed on the resin and are difficult to elute. Further, when such organic contamination is received, the functional group is clogged by the contaminant, and the exchange capacity is reduced.

(3) In the dimethylaminomethylstyrene structure, the basicity of the amine is low because the benzene ring is bonded to the carbon at the α-position of the nitrogen atom. Therefore, the types of weak electrolytes that can be adsorbed by the weakly basic anion exchange resin having this structure are limited. (4) The crushing strength of the resin is high, but the cycle strength is low. Therefore, the resin crushes as the regeneration operation is repeated,
The pressure loss of the resin bed increases.

(5) The volume change rate of the resin is large, and when an organic substance is adsorbed, the resin largely swells to cause consolidation. It has also been proposed to use a (meth) acrylic acid ester-based or (meth) acrylamide-based anion exchange resin for decolorization, but these resins have small decolorization ability,
Moreover, since the amide bond is easily hydrolyzed, the range of use is limited.

[0006]

According to the present invention, a vinylamine unit in which the nitrogen atom may be alkylated,
By contacting a liquid to be treated containing a coloring component to a cross-linked copolymer having a structure mainly composed of a polyvinyl compound unit, and adsorbing the coloring component to the cross-linked copolymer to remove it from the liquid to be treated, the above-mentioned problems can be solved. It is possible to decolorize the liquid to be treated without being accompanied.

To explain the present invention in more detail, the anion exchange resin used for decolorization in the present invention has a structure mainly composed of vinylamine units and polyvinyl compound units as a crosslinking agent. The nitrogen atom of the vinylamine unit may be alkylated with a methyl group or an ethyl group. That is, the amino group may be any of a primary to tertiary amino group and a quaternary ammonium group. From the viewpoint of decolorizing performance, the amino group is preferably a tertiary amino group, particularly preferably a dimethylamino group.

As the polyvinyl compound as the crosslinking agent, those commonly used in the field of ion exchange resins can be used. For example, an aromatic compound having two or more vinyl groups such as divinylbenzene, methyldivinylbenzene and dimethyldivinylbenzene is used. Further, poly (meth) acrylates such as ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, and trimethylolpropane tri (meth) acrylate are also used. Further, those having an amide bond such as methylenebis (meth) acrylamide can also be used. Divinylbenzene is preferably used.

The anion exchange resin used for decolorization in the present invention may contain, in addition to the above-mentioned vinylamine unit and polyvinyl compound unit, other units derived from a compound which can be copolymerized with a component giving them. . Examples of such compounds include styrene and its derivatives, (meth) acrylic acid ester, (meth) acrylamide, and acrylonitrile.

Of the above-mentioned units, the vinylamine unit is a factor that exerts a dominant influence on the decolorizing performance of the resin, and it is preferable that this unit occupied in the resin is as large as possible. This unit usually accounts for 30 to 99.5 mol%,
It should preferably comprise 40 to 95 mol%.
In one of the preferred embodiments of the present invention, decolorization is carried out by a column method in which a liquid to be treated is passed through a resin-filled column. It is preferable that the resin has a high mechanical strength such as a crushing strength and a cycle strength, and a small volume change when an organic substance is adsorbed. The most preferable amount of vinylamine units satisfying both the decolorizing performance and the above-mentioned physical performance at the same time is 70 to 90 mol%.

The polyvinyl compound unit derived from the crosslinking agent makes the vinylamine unit insoluble and imparts mechanical strength and other physical performance to the resin. This unit usually comprises 0.1 to 60 mol% of the resin, but preferably 0.5 to 40 mol%. Generally, when the number of polyvinyl compound units is increased, the mechanical strength of the resin is increased, but on the contrary, the adsorption amount of the coloring component is decreased. When the resin is used in the column method, the most preferred amount of polyvinyl compound unit is 10 to 30 mol%.

The resin used in the present invention essentially consists of the above-mentioned vinylamine unit and polyvinyl compound unit, and is usually composed of this alone. However, if desired, it may further contain a third unit as described above. This allows the resin to have various additional properties. However, when this unit is increased, the vinylamine unit is reduced and the decolorizing performance is adversely affected.

The anion exchange resin used in the present invention has the structure as described above, but from the viewpoint of the amount of ion exchange groups which greatly influence the decolorizing performance, that is, the ion exchange capacity, the exchange groups are primary amino groups. In the case of base, the exchange capacity is 8
-22 meq / g-resin, especially 10-17 meq / g-
It is preferably a resin. When the exchange group is mainly composed of a tertiary amino group, the exchange capacity is 3 to 13 meq / g.
-Resin, particularly 7-11.5 meq / g-Resin, in the case of quaternary ammonium group, neutral salt decomposition capacity is 1.5-
It is preferably 8.5 meq / g-resin, particularly 6-8 meq / g-resin.

Among the resins used in the present invention, those in which the amino group is a primary amino group are N-vinylamide, which is a compound which gives a vinylamine unit, preferably N-vinylformamide, a cross-linking agent and optionally a copolymer with these. It can be produced by copolymerizing another vinyl compound to be obtained and then hydrolyzing it to convert the amide moiety into an amino group. The resin whose amino group is a secondary or tertiary amino group or quaternary ammonium group can be easily produced by alkylating the amino group of the resin produced above by a conventional method. The polymerization can be carried out by various methods, but it is preferable to produce a spherical resin by suspension polymerization. As a polymerization bath for suspension polymerization, an organic solvent in which N-vinylamide is hardly soluble, such as toluene or petroleum ether,
Aliphatic or aromatic hydrocarbons such as cyclohexane and halogenated hydrocarbons such as polychloroalkane and chlorobenzene are used. The polymerization bath is preferably used in a volume ratio of 1 to 5 times the volume of the monomer phase composed of N-vinylamide and a crosslinking agent. If a porous resin is desired, a solvent such as acetone, 1-propanol, 2-propanol or ethanol, or methanol-1,4 may be added to the monomer phase.
By adding a mixed solvent such as -dioxane or methanol-tetrahydrofuran, the resulting crosslinked copolymer can be made porous. It is appropriate that the amount of such a solvent added is not more than 2 times the weight of the monomer. Further, instead of or together with the solvent as described above, polyvinylpyrrolidone, polyethylene glycol, ethyl cellulose or the like may be added to the monomer phase to make the resulting crosslinked copolymer porous. When the porous crosslinked copolymer is used, its specific surface area is preferably 1 to 500 m ² / g as measured by a nitrogen adsorption method. The pore diameter is 0.5 to 500 nm as measured by mercury porosimetry,
It is particularly preferably 1 to 100 nm.

A polymerization initiator is added to the monomer phase. As the polymerization initiator, water-soluble azo polymerization initiators such as 2,2-azobis-2-amidinopropane hydrochloride and 4,4-azobis-4-cyanovaleric acid are preferable. The polymerization initiator is added and dissolved in an amount of 0.02 to 5.0% by weight with respect to the monomer. In the polymerization reaction, the monomer phase is dispersed in the polymerization bath, and usually 1 to 15 at a temperature of 30 to 120 ° C.
Done on time. The degree of dispersion is preferably such that the particle diameter of the resulting crosslinked copolymer is 1 to 3000 μm, and particularly 300 to 2000 μm.

When the produced crosslinked copolymer is hydrolyzed with an acidic aqueous solution containing hydrochloric acid, sulfuric acid or the like or an alkaline aqueous solution containing alkali such as potassium hydroxide or sodium hydroxide, the amide group is easily converted into a primary amino group. Converted to. The hydrolysis may be normally performed at 50 to 120 ° C. for 1 to 10 hours. Further, by alkylating the amino group of the resin having a primary amino group, a resin having a secondary or tertiary amino group and further a quaternary ammonium group can be obtained. The amination can be carried out by a conventional method using dimethylsulfate, diethylsulfate, methyl halide, ethyl halide and the like. It is also possible to convert the primary amino group into a secondary amino group by reacting formic acid and formaldehyde.

Decolorization by the method of the present invention is carried out by bringing the above-mentioned anion exchange resin having a primary to tertiary amino group and / or quaternary ammonium group into contact with a solution for decolorization. The ion exchange group of the resin may be in a free form or a salt form. In the case of the salt type, the counter ion is usually chlorine ion, but it may be bromine ion, sulfate ion, nitrate ion or the like. The contact between the resin and the solution is usually carried out by a column method in which the anion exchange resin is packed in a column and the solution to be decolorized is passed through the column, but if desired, the resin is suspended in the solution. Let
Then, a method of separating the both by filtering can also be used.

Examples of the solution to be decolorized include fermented solutions such as amino acid fermentation, juices of fruits, various sugar solutions such as cane sugar, beet sugar and saccharified starch solution. The present invention is particularly suitable for the decolorization of sugar solutions, and can be applied to the decolorization of sugar solutions having a wide range of concentration expressed by Brix ranging from 0.5 to 80. The contact between the resin and the liquid to be treated is performed at room temperature or at an elevated temperature. Particularly in the case of a solution having a high viscosity such as a high-concentration sugar solution, it is preferable to bring them into contact with each other at an elevated temperature in order to reduce the viscosity. The upper limit of the temperature depends on the heat resistant temperature of the resin. When the ion exchange group is a quaternary ammonium group,
Although it varies depending on the counter ion, it is used at 100 ° C or lower because the heat resistance of the resin is low. In general, the Cl type is O
Since it has higher heat resistance and higher decolorization rate than H type,
Used in shape.

In the case of a weakly basic resin having a primary to tertiary exchange group, either the Cl type or the OH type may be used.
Used in molds. This is because when used in the OH type, desalting can be performed simultaneously with decolorization. In addition, since the weakly basic resin has a high heat resistance temperature, it can be decolorized at high temperature even in the OH form.
In the case of a weakly basic resin, the liquid to be treated is made acidic and brought into contact with the resin. Usually pH 5 or less, especially pH 1-3
It is preferable to adjust it to contact. When desalting is also required, the liquid to be treated is treated with a strongly acidic cation exchange resin,
It is preferable that the cation is adsorbed and the liquid property is made acidic at the same time. When the weakly basic resin is used as a mixed bed with the strongly acidic cation exchange resin, the liquid to be treated may be neutral and passed.

The resin having a reduced decolorizing ability by adsorbing a coloring component is brought into contact with an alkaline aqueous solution such as an aqueous solution of sodium hydroxide or an aqueous solution of a salt such as an aqueous solution of sodium chloride in the same manner as in the regeneration of an ordinary anion exchange resin, The adsorbed coloring component can be eluted. When the exchange group is a quaternary ammonium, the sodium hydroxide aqueous solution is usually passed to elute the adsorbed colored component, and then the sodium chloride aqueous solution is passed to make the exchange group a Cl type. .
When the exchange group is a primary to tertiary amino group, an aqueous ammonia solution, an aqueous sodium carbonate solution or the like can be used in addition to the aqueous sodium hydroxide solution. When the exchange group is used in the Cl form, the coloring component can be eluted by passing an aqueous sodium chloride solution.

According to the present invention, there are the following advantages as compared with the case of using a conventional styrene or acrylic anion exchange resin. (1) A large decolorizing capacity of several times to several tens of times can be obtained. (2) Steady-state leakage of the dye component is as small as a fraction. For example, in the case of a tertiary amine resin, even if the conventional resin has a leak rate of 30 to 40%, according to the present invention, the leak rate is reduced to 10% or less.

(3) The desorption rate, that is, the elution rate of the colored substance adsorbed during regeneration is 20 to 60% in the conventional weakly basic styrene resin, while it is about 100% in the present invention. high. It is considered that this is because the resin used in the present invention basically does not have a benzyl group and has a structure in which the hydrophobic polyethylene chain of the main chain is covered with a hydrophilic amino group.

[0023]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. In the following examples, meq / g represents milliequivalent per dry resin weight. The ion exchange capacity was measured according to the Diaion Manual (published by Mitsubishi Kasei Co., Ltd.).

[Production Example-1] Polymerization reaction: 400 ml of cyclohexane and 800 mg of ethyl cellulose were placed in a 1000 ml four-necked flask to prepare a polymerization bath. N-vinylformamide (purity 94
%, Impurities are mainly formic acid) 176 g, divinylbenzene (purity> 80%) 24.0 g, demineralized water 4.5 g, V-5
0 (azo polymerization initiator, trade name, manufactured by Wako Pure Chemical Industries, Ltd.) 4
A monomer solution was prepared by mixing 00 mg. Both solutions were bubbled with nitrogen before being subjected to the reaction, and the polymerization reaction was carried out under a nitrogen atmosphere. The monomer solution was gradually added dropwise while stirring the polymerization bath at 100 rpm. After stirring for 30 minutes, the temperature was raised and polymerization was carried out at 65 ° C. for 8 hours. After the temperature was raised, the monomer solution gelled in about 15 minutes. After the polymerization was completed, the crosslinked copolymer produced was collected by filtration, washed with methanol and then washed with water. The polymerization yield was 81% based on the raw material monomers. The resulting crosslinked copolymer was white in appearance, but was slightly opaque when observed under a microscope. Specific surface area is 0m
It was ² / g.

Hydrolysis reaction: The above cross-linked copolymer was placed in a 1-liter flask and 700 ml of a 2N sodium hydroxide aqueous solution was added. The solution was warmed and hydrolyzed at 85 ° C. for 4 hours. The degree of swelling of the obtained cross-linked copolymer is 7.
It was 33 ml / g and the water content was 78.9%. Weak base exchange capacity is 18.0 meq / g, 2.46 meq / m
It was l. As a result of ¹³ C-NMR (CP-MAS method), the formin group (164 ppm) was completely disappeared.

[Production Example-2] Methylation reaction: Wet weakly basic resin 10 obtained in Production Example-1
0 ml and 100 ml of demineralized water were placed in a 1000 ml flask, and 40 g of sodium formate and 81 g of 37% aqueous formaldehyde solution were added. Further, hydrochloric acid was added to adjust the pH to 5. The temperature was gradually raised and the reaction was carried out at 90 ° C. for 5 hours. Carbon dioxide gas was generated violently in the initial stage, but it almost disappeared at the end of the reaction. After completion of the reaction, the resin is washed with water, and then O is washed with 0.1N-sodium hydroxide aqueous solution.
It was H type. The weak base exchange capacity of the obtained resin is 9.3 m.
eq / g, average particle size was about 340 μm. The water content was 67.7% and the degree of swelling was 4.77 ml / g.
The degree of methylation of the amino group was measured by ¹³ C-NMR (CP-MAS
The degree of methylation is 1.8
Met. It is considered that 80% or more of the amino groups are tertiary amino groups, and the balance remains as primary amino groups or secondary amino groups.

[Production Example-3] A copolymer was synthesized in the same manner as in Example-1 except that 160 g of N-vinylformamide and 42 g of divinylbenzene were used in the monomer solution. And was hydrolyzed. Furthermore, the amino group was made tertiary by the same method as in Production Example-2. The weak base exchange capacity of the obtained resin is 8.5 meq /
g, average particle diameter was about 390 μm. Moisture content is 6
The swelling degree was 2.2% and the swelling degree was 3.89 ml / g. The methylation degree of the amino group was 1.7. 80 of the amino groups
% Or more is a tertiary amino group, and it is considered that a part thereof remains as a primary amino group or a secondary amino group.

[Production Example-4] Methylation reaction: To a 500 ml four-necked flask, 50 ml of the wet weak basic resin obtained in Production Example-1 and 150 ml of a 50% aqueous methanol solution were added. An aqueous solution containing 30 ml of methyl iodide, 50 ml of 50% aqueous methanol solution, and 28 g of sodium carbonate was slowly added dropwise thereto. After the reaction was completed, the resin was collected by filtration and washed with methanol and demineralized water. The obtained resin has a neutral salt decomposition capacity of 6.3 m.
eq / g, weak base exchange capacity was 1.9 meq / g, and average particle size was about 340 μm.

[Preparation of sugar solution-1] About 750 g of crude sugar was added to about 75
The sugar solution was dissolved in 0 ml of demineralized water to prepare Brix at 50.0. This solution was It was filtered through 5C filter paper. On the other hand, 2.0 kg of commercially available granulated sugar was dissolved in about 2 liters of demineralized water, and Brix was adjusted to 50.0
A sugar solution was prepared so that 1.5 parts of both solutions to 3.
After mixing at a ratio of 5 parts, sugar solution-1 was prepared by further diluting with the same volume of demineralized water. The Brix of this solution is 27.
It was 8.

[Preparation of Sugar Solution-2] A granulated sugar solution and a crude sugar solution of Brix 50 were prepared in the same manner as in the preparation of sugar solution-1, and both were mixed at a ratio of 1: 1 to prepare a sugar solution of Brix 50-2. Was prepared.

[Evaluation Method of Decolorizing Performance of Weakly Basic Resin] 2
Diaion (registered trademark) S completely regenerated with N-hydrochloric acid
The sugar solution prepared above was passed through a column filled with 300 ml of K1B (strongly acidic cation exchange resin) with SV5 hr ⁻¹ to remove cations from the sugar solution. PH of the obtained sugar solution
After heating this through a thermostatic bath at 1.5 to 2.2,
Weakly basic resin column completely regenerated with 2N-sodium hydroxide aqueous solution (glass column with jacket (14 mmφ ×
40cm layer height about 35cm, resin amount 50ml)) SV5
The solution was passed at hr ^-1 . The electric conductivity and the absorbance (4
20 nm) was measured.

[Evaluation Method of Decolorizing Performance of Strongly Basic Resin] A decolorizing test was conducted in the same manner as in the case of the weakly basic resin except that the sugar solution was not passed through the column of the strongly acidic cation exchange resin.

[Measurement of Absorbance] The sugar solution was adjusted to pH 7.0 ± 0.1 with 1N hydrochloric acid or sodium hydroxide aqueous solution. This sugar solution was filtered with a 0.45 μm filter, and the absorbance of the filtrate was measured at 420 nm. The measurement of the absorbance uses a 50 mm cell in Example-1,
In Example-2, a 10 mm cell was used.

[Elution of Coloring Component] The resin used in the decolorization test was taken out in a beaker and poured again into the column with demineralized water to obtain a column in which the coloring component was uniformly distributed. Next, in the case of a weakly basic resin, 1N-sodium hydroxide aqueous solution of 1.5 times equivalent to the weakly basic exchange capacity is passed through SV2hr ^-1 at the same temperature as the passing temperature of the sugar solution to elute the colored component. The resin was then washed with 5 times the amount of demineralized water with respect to the resin. All the effluents were combined, diluted with demineralized water and used for the measurement of absorbance.
Further, in the case of a strongly basic resin, 1.5 times the equivalent of 1M-aqueous sodium chloride solution with respect to the neutral salt decomposing capacity and 0.1
It was carried out in the same manner as in the case of the weakly basic resin, except that a mixed solution of 5 times equivalent of 1N-sodium hydroxide aqueous solution was used.

[Example-1] Using the sugar solution-1, the decolorizing performance of the resin was evaluated at 50 ° C. The results are shown in Table-1. The weakly basic resin was OH type and the strongly basic resin was Cl type.

[0036]

[Table 1] * 1 DIAION (registered trademark) PA308 (porous styrene-based strongly basic anion exchange resin) * 2 DIAION (registered trademark) WA30 (porous styrene-based weakly basic anion exchange resin) * 3 Leakage rate is 10 The amount of processing to reach%. The leak rate was calculated as the ratio of the absorbance of the decolorized sugar solution at 420 nm to the absorbance of the test sugar solution at 420 nm. As the absorbance of the test sugar solution of the weakly basic resin, the absorbance of the sugar solution after being treated with the strongly acidic cation exchange resin was used. * 4 The conductivity of the test sugar solution is 140 μS / cm before the treatment with the strongly acidic cation exchange resin, and 500 μS / cm after the treatment.
It was cm. * 5 The desorption rate was calculated as the ratio of the absorbance of the eluent at 420 nm to the absorbance of the test sugar solution at 420 nm. * 6 The decolorization rate is the decolorization rate when the leakage of the coloring component into the column effluent is almost constant and the breakthrough of the coloring component does not occur.

[Example-2] Using the sugar solution-2, the decolorizing performance of the resin was evaluated at 60 ° C. The results are shown in Table-2.

[0038]

[Table 2]

Example 3 A resin regenerated by eluting a coloring component from the resin used in Example 2 was added to the resin at 60 ° C.
2 was passed to evaluate the decolorizing performance of the resin. The results are shown in Table-3.
Shown in.

[0040]

[Table 3]

[0041]

According to the present invention, a solution containing a coloring component can be efficiently decolorized by using a resin essentially consisting of a vinylamine unit and a crosslinking unit and having a large exchange capacity.

Continuation of the front page (56) Reference JP-A-6-238270 (JP, A) JP-A-5-49951 (JP, A) JP-A-3-112500 (JP, A) JP-A-6-190235 (JP , A) JP-B 56-1080 (JP, B1) JP-A 2-503634 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B01D 15/00 B01D 15/04 C13D 3/14

Claims (5)

(57) [Claims] 1. A crosslinked copolymer having a structure mainly composed of a vinylamine unit in which a nitrogen atom may be alkylated and a polyvinyl compound unit is brought into contact with a liquid to be treated containing a coloring component, and the coloring component is crosslinked. A bleaching method characterized by adsorbing to a solution to be removed from a liquid to be treated. 2. The crosslinked copolymer has a vinylamine unit of 3
0-99.5 mol%, polyvinyl compound unit 0.1-
The bleaching method according to claim 1, wherein 60 mol% and 0 to 40 mol% of the vinyl compound unit capable of being copolymerized therewith. 3. The crosslinked copolymer has a vinylamine unit of 7
0 to 90 mol%, polyvinyl compound units 10 to 30 mol%, and 0 to 2 vinyl compound units copolymerizable therewith
The bleaching method according to claim 1, wherein the bleaching method comprises 0 mol%. 4. The vinylamine unit comprises a methyl group and / or
Alternatively, the decolorizing method according to any one of claims 1 to 3, which is an N, N-dialkylvinylamine unit alkylated with an ethyl group. 5. The decolorizing method according to claim 1, wherein the liquid to be treated is a sugar liquid.