JPH0547269B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for decolorizing a solution that contains impurities, mainly pigment components, and is colored with a high color value.In particular, the present invention relates to a method for decolorizing a solution that is colored with a high color value and contains impurities, mainly pigment components.In particular, the present invention relates to a method for reusing a used anion exchange resin whose capacity has decreased due to use in other processes. The present invention relates to a method, and more particularly, to a method for desorbing contaminants such as pigments deposited and accumulated in a resin that cannot be desorbed by any method in the form of a particulate ion exchange resin. In particular, the present invention relates to improvements in decolorizing methods using powdered anion exchange resins, including methods for regenerating powdered anion exchange resins prepared by pulverizing used granular anion exchange resins. It has been known that anion exchange resins are effective not only for desalination but also for decolorization, and are used, for example, in the decolorization process in the sugar refining industry.
In terms of usage, the particle size is generally
It is known that an adsorption tower is filled with granular anion exchange resins of 0.3 to 0.6 mm, and a liquid to be treated is passed through the packed bed to adsorb a dye component in the solution. This method of passing the liquid to be treated through the packed bed is relatively easy to operate because it simply passes the liquid through the packed bed, but on the other hand, the processing capacity is low because the adsorption surface area is small and the adsorption speed is slow. It has the disadvantage that the liquid passing rate cannot be made very high. For this reason, the adsorption tower tends to be relatively large, and the utilization rate relative to the theoretical adsorption capacity is also relatively small. Therefore, it has been considered to utilize a powdered anion exchange resin having a large adsorption surface area for the above-mentioned decolorization. By using this powdered anion exchange resin, the flow rate of the liquid to be treated can be greatly increased, and the utilization rate relative to the theoretical adsorption capacity can also be increased, making it possible to effectively decolorize with a small amount of resin. can. By the way, when a granular anion exchange resin is packed in a packed tower or the like and used for decolorizing or desalting various solutions, as it is used, the through-flow capacity decreases and the purity of the treated liquid decreases, resulting in a decrease in its capacity. decreases.
In general, the decrease in the ability of granular anion exchange resins is due to
There are two possible causes: a decrease in exchange capacity and a decrease in the diffusion rate within particles due to so-called organic contamination, in which organic substances are irreversibly adsorbed onto the particle surface. It is known that the anion exchange resin cannot be removed and the performance of the anion exchange resin cannot be restored to its original state. Therefore, the granular anion exchange resin is replaced with a new one at some point and discarded as industrial waste. This is thought to be the same for the above-mentioned powdered anion exchange resins, and powdered anion exchange resins with reduced performance are also disposed of. If the anion exchange resin is made disposable in this manner, the running cost not only increases because the anion exchange resin is expensive, but also the disposal of the used resin, which is industrial waste, becomes a problem. Particularly when processing high color value solutions, the above-mentioned problem becomes even more pronounced because the resin must be replaced frequently. As a result of intensive studies in view of the above-mentioned circumstances, the inventors of the present invention have found that used granular anion exchange resin, which has been used once in another process and is no longer usable, is pulverized into a fine powder and brought into contact with a certain type of solvent. The inventors have now completed the present invention by discovering that the adsorbed substances, which could not be desorbed in the granular state, can be quickly removed and the product can be regenerated as if it were new, and furthermore, it can be used repeatedly through regeneration. In order to decolorize the solution by contacting the powdered anion exchange resin, the used granular anion exchange resin as the powdered anion exchange resin is pulverized into fine particles with a particle size of 105 μm or less, and then acid and/or alkali are added. Using a powdered anion exchange resin obtained by regenerating it by contacting it with a metal ion-containing solution, and regenerating the powdered anion exchange resin that has adsorbed the adsorbed substance through the decolorization by bringing it into contact with an acid-containing solution, It is characterized by repeated use. Hereinafter, embodiments of the present invention will be described with reference to FIG. In the present invention, the powdered anion exchange resin 1 is used to decolorize the solution, but in order to produce the powdered anion exchange resin 1,
A used granular anion exchange resin 2 is prepared. The used particulate anion exchange resin 2 may be one that is used in various decolorization processes, desalination processes, etc. and is originally discarded, as described above. In addition, the types include a copolymer of styrene and divinyllebenzene or a copolymer of acrylic and divinylbenzene, etc., with a quaternary ammonium group,
Strongly basic anion exchange resins, medium basic anion exchange resins, weakly basic anion exchange resins having ion exchange groups such as alkanol groups, tertiary amine groups, secondary amine groups, primary amine groups, polyamine groups, etc. Any anion exchange resin such as ion exchange resin can be used, and its ionic form can be OH, Cl, etc.
Although various salt forms such as OH form and SO ₄ form can be mentioned, strongly basic anion exchange resins such as OH form and Cl form are the most effective. Next, this used granular anion exchange resin 2 is crushed into fine particles in a crushing step 3. The particle size of the fine particles obtained by this pulverization step 3 is as follows:
It is preferably 105 μm or less. The above particle size is
If the diameter exceeds 105 μm, it becomes difficult to remove adsorbed substances, mainly dye components, and regeneration, which will be described later, becomes difficult. In addition, the particle size of the above powdered ion exchange resin is 5 μm or less, especially 1.5 μm, which has a high risk of leakage.
If the resin is less than m, it will be difficult to separate by filtration, and there is a risk that the resin will be mixed into the decolorizing solution described below. Further, examples of the pulverization method include a pneumatic pulverization method, a frozen powdered sand method, a mechanical pulverization method, etc., and it is particularly preferable to use a pneumatic pulverization method or a freeze pulverization method. The above-mentioned pneumatic pulverization method is a method in which the particulate anion exchange resin, which is the raw material, is self-pulverized into fine particles by vibration caused by high-frequency pressure fluctuations caused by high-speed swirling of air, and the time required to powder it to 50 μm or less is It has the characteristic of being extremely short-lived (about a few seconds). According to this pulverization method, the temperature rise during pulverization is 40℃ or less, so there is no deterioration of the resin due to heat, and when the effective particle size is 5 to 50 μm, the production rate is as high as 99.9%. reach A further characteristic feature is that a powdered anion exchange resin can be obtained which has excellent desorption properties of pigment components and has a large regeneration and regeneration effect. In addition, the above-mentioned freeze-pulverization method involves directly contacting granular anion exchange resin with, for example, liquid nitrogen.
The anion exchange resin is cooled to below .degree. C., and then the cooled anion exchange resin is immediately pulverized using a hammer mill or the like. In addition to the above-mentioned liquid nitrogen, refrigerants that can be used for the above-mentioned cooling include various low-boiling point liquefied gases such as liquid carbon dioxide, liquid oxygen, and liquefied propane. Preferably, liquid nitrogen is used on the surface. In this case as well, a powdered anion exchange resin having a fine particle size and a relatively uniform particle size can be obtained without thermal deterioration. On the other hand, with mechanical pulverization using a ball mill or hammer mill, it is difficult to make the particle size of the pulverized material uniform, and when using the obtained powdered anion exchange resin, it is necessary to sieve it to a size of 105 μm. It is preferable to select and use the following. Furthermore, in the above-mentioned mechanical pulverization method, the time required for pulverization is long and the temperature rise is large, so there is a possibility that the decolorizing performance of the powdered anion exchange resin may be reduced. The heat resistance of anion exchange resins is relatively low. For example, the maximum operating temperature of OH type strongly basic anion exchange resins with quaternary ammonium groups as ion exchange groups is said to be 60℃, and if this temperature is exceeded, Thermal decomposition of the ion exchange groups occurs rapidly. Although the details of the adsorption mechanism of dye components by anion exchange resin are unknown, it is thought that the polarity of the anion exchange resin particle surface is largely involved.
It is undesirable that heat is applied during the grinding. Subsequently, the resin made into fine particles in the pulverization step 3 is regenerated in a regeneration step 4. The regeneration agent used in the regeneration step 4 is as follows:
Examples include solutions containing acids and/or alkali metal ions, and as the solution containing acids and/or alkali metal ions, acid-containing organic solvents or alkali metal ion-containing organic solvents are effective. Acid-containing acetone, acid-containing methanol, and alkali metal ion-containing methanol as organic solvents are effective. In addition, when an organic solvent such as ethanol, ether, chloroform, or hexane is used as the organic solvent, there is also an effect of desorbing the dye component. Further, examples of the acid include hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, formic acid, acetic acid, etc., but it is more effective to use a mineral acid such as hydrochloric acid. Furthermore, as the alkali metal ion-containing solution, saline solution, sodium hydroxide-containing saline solution,
Although it is effective to use a saline solution containing hydrochloric acid, its regeneration effect is inferior to that of the above-mentioned acid-containing acetone and the like. Most preferably, it is first contacted with a solution containing acid and/or alkali metal ions, followed by contact with an organic solvent containing acid and/or alkali metal ions. The most effective regenerants for regenerating powdered anion exchange resins are acids and/or
Or it was an organic solvent containing alkali metal ions.
Although this tendency does not change even in the case of the powdered anion exchange resin according to the present invention, the following phenomenon has been clarified as a unique phenomenon in the case of the used powdered ion exchange resin. It has been found that the used powdered ion exchange resin referred to in the present invention has a great regeneration effect not only in organic solvents but also in aqueous solutions. The reason for this is
Used granular anion exchange resin (waste resin) with reduced decolorizing ability had accumulated a large amount of impurities that could not be desorbed in granular form, and the accumulated pigments were desorbed by being made into fine particles. It is presumed that this is because the condition has become easier. In other words,
It was found that the equilibrium relationship between adsorption and desorption of pigments, etc. is different between granular and powdered materials. In the case of a used powdered ion exchange resin, it is not necessarily necessary to repeatedly use it over many cycles from an economic standpoint. Therefore, regeneration using the aqueous solution alone is sufficient, but in order to use it over multiple cycles,
It has also been found that it is advisable to use a regeneration method in which contact is made with an organic solvent, especially acetone water containing an acid. The frequency of incorporating regeneration with an organic solvent is not constant as it is affected by the amount of impurities (dye) in the liquid to be treated, but the combined effect may be noticeable by performing it once every 5 to 10 cycles. Admitted. By the way, as for the acid concentration in the acid-containing organic solvent, the desorption rate increases as the concentration increases, but even when the acid concentration increases to 5% or more, the amount of desorption does not increase significantly. Furthermore, when acid-containing acetone was used, no difference was observed in the desorption performance up to a water content of around 50%. When regenerating the above-mentioned fine-particle anion exchange resin using a regeneration agent containing a highly permeable organic solvent such as acetone, the desorption rate is extremely fast, and the adsorption is possible even after a short period of contact. It is possible to almost completely remove the pigment components, etc. In addition, when an aqueous solution is used as the regeneration agent,
It is necessary to use a large amount of regeneration agent and the conditions for its use must be high temperatures, but when using a regeneration agent that is mainly based on organic solvents, the amount used can be significantly reduced. Usually, 10 to 20 times the amount of regenerated resin is sufficient. When using a regeneration agent mainly composed of the above-mentioned organic solvent, the organic solvent used for regeneration can be easily recovered and reused by distillation, etc., and the amount of waste liquid can be reduced. , the benefits are great.
Furthermore, when recovering the organic solvent, there is also the effect of facilitating the recovery of valuable substances in the waste liquid. Through the above-mentioned regeneration step 4, adsorbed substances that accumulate inside the resin pores of the used granular anion exchange resin 2, especially colloidal components containing polymeric dyes and heavy metals, are easily removed, and the powdered anion exchange resin becomes as good as new. Exchange resin 1 is obtained. Then, the colored solution 5 to be treated is passed through the powdered anion exchange resin 1 to obtain a decolorized solution 6. The powdered anion exchange resin 1 has better performance than bone char or granular activated carbon in terms of decolorizing action, and the purpose can be sufficiently achieved by using the resin in an amount of 0.5% based on the solution to be treated 5. Furthermore, this amount can be significantly reduced by adopting a multi-stage contact method or a powder resin layer method. Therefore, the amount of solution purified per unit amount of resin increases significantly, and in particular, in the powder resin layer method, the amount is about 10 times that of the conventional method using granular anion exchange resin. In addition, when creating the powdered resin layer, a powdered anion exchange resin, diatomaceous earth, and a fibrous filter aid may be used in combination. In addition, when the powdered anion exchange resin 1 is used, the liquid to be treated 5 has a color value index of AI
(Attenuation Index) A high color value solution of 100 or more can decolorize most effectively. Furthermore, the powdered anion exchange resin 1 not only has a larger adsorption amount than the granular anion exchange resin, but also has specificity for polymeric dyes that have absorbance characteristics in the visible high wavelength region of 560 to 720 nm. It was found that the amount of adsorption was large. On the other hand, if the decolorizing ability of the powdered anion exchange resin 1 begins to decline, it is regenerated in a regeneration step 7. The regenerating agent used in this regeneration step 7 may be the same as the regenerating agent used in the previous regeneration step 4. For example, the powdered anion exchange resin 1 is brought into contact with stirring in batches to remove pigment components, etc. The adsorbed substance is desorbed and used again to decolorize the treated object 5. The present invention can be applied to decolorizing any solution as long as it contains a pigment component that can be adsorbed by the powdered anion exchange resin 1, but in particular various sugar solutions such as cane sugar solution and sugar beet solution. It has a very large regeneration effect and is useful when applied to decolorizing various plant juices, pulp factory waste liquid, food factory waste water, etc. In particular, when applied to the purification of sugar solutions, the above-mentioned powdered anion exchange resin and powdered anion exchange resin can be used in combination, for example, in sugar solutions treated in the magnesia cleaning process or the carbonate filling process. It is also possible to remove the hardness component of , and the purification process can be omitted. As described above, according to the present invention, used granular anion exchange resin, which should originally be discarded, can be regenerated and used as if it were new, and furthermore, it can be regenerated with a regenerating agent and used repeatedly. Therefore, the economic merit is extremely large, and the amount of industrial waste is significantly reduced, which is preferable from the viewpoint of processing labor and pollution. Furthermore, since the powdered anion exchange resin has an extremely high decolorizing ability, it is possible to improve treatment efficiency and reduce decolorizing costs. Next, specific examples will be described in order to make the present invention more clear, but it goes without saying that the present invention is not limited to these examples. Example 1 Used granular strongly basic anion exchange resin whose capacity has decreased due to use in the ion exchange resin process for purification of cane sugar liquid is ground in a ball mill to form a powder having a particle size distribution as shown in Table 1. Anion exchange resin was prepared by sieving method. 1 g (dry weight) of powdered anion exchange resin having each of these particle size distributions was regenerated at a temperature of 70° C. using 50 ml of 10% saline containing 1% HCl. The regenerated effluent obtained from this regeneration operation is neutralized to pH7.
It was diluted to 200 ml, and the absorbance of this waste liquid was measured using a spectrophotometer, and the amount of desorbed dye in each particle size distribution was compared based on the absorbance. Furthermore, the amount of heavy metals remaining in the powdered anion exchange resin regenerated by the regeneration operation was measured based on the official food additive analysis method. The results are shown in Table 1.

[Table] As is clear from Table 1, in the state of granular anion exchange resin (particle size of 250 μm or more), almost no pigment component was desorbed, whereas
By making the particles smaller than 105 μm, especially 105 μm or less, the amount of desorbed dye is greatly improved, and the residual heavy metals are also reduced, improving the regeneration effect. In particular, the absorbance at 600 μm was more than 100 times higher, indicating that it was possible to desorb polymeric dye components that could not be removed using conventional granular anion exchange resins. Example 2 Purification of cane sugar liquid Used granular strong basic anion exchange resin whose capacity has decreased due to use in the ion exchange resin process is pulverized to a particle size of 50 μm or less (average particle size 18.5 μm) using an air flow pulverization method. 50 ml of the regenerating agent shown in Table 2 was added to 1 g (dry weight) of the obtained powdered anion exchange resin, and the mixture was brought into contact with the resin for 30 minutes while stirring. Table 2 shows the amount of dye desorbed by each regenerating agent and the amount of heavy metals remaining in the resin. Note that the above regeneration was performed at room temperature when the regeneration agent was mainly an organic solvent, and at 70° C. when the regeneration agent was mainly an aqueous solution. Further, the amount of the desorbed dye was calculated only for the dye component having absorbance at 420 nm, and the calculation method was based on the following formula. Desorption dye amount = 1000 (-logT _420on ) / cell length (cm) x resin amount (g) x drainage volume (ml)

[Table] From this Table 2, it can be seen that the desorption effect is excellent in regenerating agents mainly composed of organic solvents, and especially in 1% solutions containing acids and/or alkali metal ions.
It has been found that the pigment component can be removed extremely effectively by contacting with 10% NaCl water containing NaOH, and then with 80% methanol water containing 5% HCl, which is an organic solvent containing acid and/or alkali metal ions. it is obvious. Example 3 Purification of cane sugar liquid Used granular strong basic anion exchange resin whose capacity has been reduced due to use in the ion exchange resin process is pulverized to a particle size of 50 μm or less (average particle size 18.5 μm) using an air flow pulverization method. A powdered anion exchange resin was obtained. 1 g (dry weight) of the obtained powdered anion exchange resin was added to 200 ml of refined intermediate sugar solution (Bx60, PH8.0, invert sugar 0.16%, color value rbu1237) after the carbonation process at a refined sugar factory. The dye component was adsorbed while stirring at 70°C for 30 minutes. After the adsorption is completed,
Filter the powdered anion exchange resin using a 0.8μ membrane filter, wash with water, and collect 100ml.
Transferred to a beaker. Add 20 ml of acetone and 2 ml of 36% concentrated hydrochloric acid to the powdered anion exchange resin that has adsorbed the pigment component.
Stir for 15 minutes on a magnetic stirrer to regenerate, and transfer the powdered anion exchange resin to filter paper (No. 2).
It was filtered using The same operation was carried out twice, the regenerated waste liquid was combined and neutralized with NaOH solution, and then 200
ml and measure the absorbance using a spectrophotometer.
The dye desorption rate was determined. The above dye desorption rate is determined by the formula: Dye desorption rate = Color value of recycled effluent (rbu) / Color value reduced by decolorization (rbu) x 100 (%), and the color value (rbu) is calculated at 420 nm and
Calculated from absorbance at 720 nm. Color value (rbu) = 1000 x (-logT _420on + 2logT _720on )
/b×c (In the formula, b represents the cell length and c represents the sugar concentration of the sample.) After thoroughly washing the powdered strong basic anion exchange resin after the regeneration operation, Using the purified intermediate sugar solution after the carbonation process described above as the treatment liquid,
Decolorization and purification → Powdered anion exchange resin recovery → Regeneration →
Decolorization and purification... were repeated. We performed repeated operations for 10 cycles, but
No decrease in decolorizing ability was observed. Table 3 shows the quality of the treated sugar solution in each cycle and the dye desorption rate in each regeneration operation.

【table】

[Table] Example 4 Granular strong basic anion exchange resin (trade name: Diaion) used for 300 cycles in the desalination process
PA308) was pulverized by an air flow pulverization method to obtain a powdered anion exchange resin (average particle size 23 μm). 1 g (dry weight) of the obtained powdered anion exchange resin was added to 10 g of colored wastewater from a food factory, and the mixture was heated at room temperature.
Stir and process for 20 minutes. After the above treatment was completed, the powdered anion exchange resin was filtered through a 10μ membrane filter and collected into a 200ml beaker. 100 ml of 80% methanol water and 10 ml of concentrated nitric acid (48%) were added to the recovered powdered anion exchange resin, and ultrasonic stirring was continued for 30 minutes. Subsequently, the powdered anion exchange resin was collected using a 10μ membrane filter, and after washing, the same operation was repeated for three cycles using the colored wastewater described above, but almost no decrease in decolorization ability was observed. The results are shown in Table 4. Note that SS in Table 4 was measured by the method of JIS K0102.

【table】 [Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the steps of a method for decolorizing a solution to which the present invention is applied.

Claims (1)

[Scope of Claims] 1. When bringing a solution into contact with a powdered anion exchange resin to decolorize it, the used granular anion exchange resin as the powdered anion exchange resin is
Using a powdered anion exchange resin obtained by regenerating it by grinding it into fine particles of 105 μm or less and contacting it with a solution containing acid and/or alkali metal ions, and also powdered anions that have adsorbed the adsorbed substance by the above-mentioned decolorization. A method for decolorizing a solution, characterized in that an exchange resin is brought into contact with an acid-containing solution to be regenerated and used repeatedly. 2 Decolorization of the solution according to claim 1, characterized in that the powdered anion exchange resin that has adsorbed the adsorbed substance by decolorization is regenerated by contacting it with a regenerant containing an acid and a hydrophilic organic solvent. Method. 3. The powdered anion exchange resin that has adsorbed the adsorbed substance by decolorization is brought into contact with an aqueous solution containing an acid and/or an alkali metal ion, and then regenerated by contacting with a regenerant containing an acid and a hydrophilic organic solvent. A method for decolorizing a solution according to claim 1. 4. The method for decolorizing a solution according to claim 2 or 3, wherein the hydrophilic organic solvent is an alcohol or a ketone. 5. The method for decolorizing a solution according to claim 1, wherein the solution is a sugar solution. 6. The solution according to claim 5, characterized in that the used granular anion exchange resin is a granular anion exchange resin whose capacity has decreased after being used in a cane sugar liquid purification ion exchange resin process. Bleaching method.