JPH04200743A - Regeneration of activated carbon fiber - Google Patents

Abstract

PURPOSE:To effectively regenerate an activated carbon fiber by a method wherein the activated carbon fiber lowered in its capacity is subjected to washing at specific temp. or lower, washing at the specific temp. or higher, the treatment with an alkali aqueous solution, washing at the specific temp. or higher, pickling and washing. CONSTITUTION:In treating a fermentation solution such as alcoholic liquors or liquid seasonings, food such as a sugar solution or an intermediate product thereof with an activated carbon fiber (e.g. polyacrylonitrile type activated carbon fiber) to discolor the same, the activated carbon fiber lowered in its capacity is regenerated by executing the following first-sixth processes. That is, said fiber is washed at 35 C or lower in the first process, washed at 50 deg.C or higher 10 the second process, treated with a 0.1-4.5wt.% alkali aqueous solution at 40 deg.C or higher in the third process, washed at 50 deg.C or higher 10 the fourth process, treated with a 0.1-3wt.% acid solution at 15-40 deg.C in the fifth process and washed in the sixth process. As a result, the activated carbon fiber lowered in its capacity can effectively be regenerated.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention is directed to fermented liquids such as alcoholic beverages and seasoning liquids, or foods such as sugar solutions, or intermediates thereof (hereinafter collectively referred to as "foods").

) and relates to a method for regenerating activated carbon fibers whose performance has deteriorated.

According to the recycling method of the present invention, activated carbon fibers used in the production of these foods can be effectively recycled.

[Prior art and its problems]

A method for recycling activated carbon fibers conventionally used in the production of food products is proposed in Japanese Patent Application Laid-Open No. 157968/1983.

In this method, activated carbon fibers requiring regeneration treatment are regenerated in the next step.

However, since this method is an incomplete treatment method before alkaline treatment, when food products are repeatedly decolorized and regenerated, the performance deteriorates significantly, and once every few ten times, the temperature is 500℃.
Gas treatment (hereinafter referred to as "high-temperature gas treatment") must be performed at a temperature below 950°C, and this high-temperature gas treatment may cause a decrease in the weight of the activated carbon fibers or a decrease in the strength of the activated carbon fibers. However, there was a problem in that it caused fine powder to be mixed into foods.

[Purpose of the invention]

An object of the present invention is to provide a method for effectively regenerating activated carbon fibers that are used for decolorizing foods and whose performance has deteriorated.

[Structure and effects of the invention]

The present invention is as follows.

When activated carbon fibers are used to treat and decolorize fermented liquids such as alcoholic beverages and seasoning liquids, or foods such as sugar solutions, or their intermediates, the activated carbon fibers with degraded performance are A method for regenerating activated carbon fibers, characterized in that each of the sixth steps is regenerated in this order.

1st step: Washing with water at a temperature below 35℃ 2nd step
3rd step of washing with water at a temperature of 50°C or higher; 4th step of treating with an alkaline aqueous solution of 0.1% by weight or more and 4.5% by weight or less at a temperature of 40°C or higher; 4th step of washing with water at a temperature of 50°C or higher. 5 steps
Acid washing step 6th step Water washing step In the case of the present invention, since the temperature in the first step is as low as 35°C or lower, there is no denaturation of proteins that are easily denatured at low temperatures.
Therefore, denatured proteins are not immobilized while remaining attached to the activated carbon fibers.

According to the regeneration method of the present invention, even if the regeneration process is repeated,
It has a high performance retention rate, and therefore, decolorization and regeneration can be repeated over a long period of time without performing high-temperature gas treatment.

In the present invention, the activated carbon fiber used as an adsorbent is one manufactured by a known method such as polyacrylonitrile activated carbon fiber, phenol activated carbon fiber, cellulose activated carbon fiber, or pinch type activated carbon fiber. be. Among these activated carbon fibers, polyacrylonitrile activated carbon fibers are particularly desirable.

The reason is polyacrylonitrile activated carbon fiber,
This is because it has a larger pore diameter than other activated carbon fibers, so it has a high decolorizing performance for foods and is easily recycled.

In addition, since polyacrylonitrile-based activated carbon fibers have higher strength than other activated carbon fibers, there is little deterioration even after repeated recycling, and there is little generation of fine powder.

Regarding the specific surface area and pore volume of the activated carbon fibers used, it is generally desirable that the specific surface area is 1000Ill'/g or more and the pore volume is 0.65 cc/g or more.

The regeneration process of the present invention is shown in FIG. 1. FIG. 1 shows a cycle of a food decolorization process and a regeneration process. The present invention will be explained below with reference to FIG.

The objects of the present invention are fermented liquids such as alcoholic beverages and seasoning liquids, foods such as sugar solutions, or intermediates thereof. These include coloring components such as melanoidins and humins.

Specifically, the objects of the present invention include sugar solutions, mirin, alcoholic beverages such as sake, fruit wine, shochu, and whisky, soy sauce, lactic acid drinks, amino acid drinks, lactic acid or amino acid manufacturing process liquids, and the like.

(First step: First water washing) Activated carbon fibers whose performance has deteriorated must first be washed with water at 35° C. or lower. If the temperature is higher than 35°C, substances that are easily denatured, such as proteins contained in trace amounts in foods, will remain attached to the activated carbon fibers and become immobilized, making it difficult for them to be removed during subsequent regeneration steps. This in turn causes irreversible reproduction defects.

For washing, C0D (JIS K-010
It is preferable to carry out the process until the value (measured according to 2) becomes 50 ppm or less, or the absorbance (00,.) in a quartz cell with an optical path length of IO+m at a wavelength of 280 nIi of the washing waste water becomes (1.3 or less).

(2nd step: 1st warm water washing) Next, it is washed with 50°C warm water.

If this step is not performed, substances such as saccharides attached to the surface of the activated carbon fibers will remain in the next alkali treatment step, increasing the burden of regeneration and eventually causing poor regeneration.

It is preferable to wash with hot water until the COD value of the hot washing wastewater becomes 1100 pp or less, or until the 0D280 of the hot washing wastewater becomes 0.5 or less.

(Third step, alkaline treatment) Next, treatment is performed with an alkaline solution of 0.1% by weight or more and 45% by weight or less at 40° C. or higher. The type of alkaline solution is not particularly limited, but aqueous solutions such as sodium hydroxide and potassium hydroxide are desirable.

If the temperature here is less than 40°C, performance will deteriorate if decolorization and regeneration are repeated.

Further, the upper limit of the temperature is preferably 95° C. or lower from the viewpoint of operability.

Furthermore, if the alkali concentration is less than 0.1% by weight, performance will similarly deteriorate. On the other hand, the alkali concentration is 4,5
If it exceeds % by weight, the single fiber strength of the activated carbon fibers decreases and fine powder is likely to be generated when recycling is repeated.

A particularly preferred concentration range is 0.3wtX to 4.0wtX.

For alkaline treatment, the COD value of alkaline treated effluent is 40p.
It is preferable to carry out the treatment until the absorbance of the lco+ cell at 280 nm of the alkali-treated wastewater becomes 0.2 or less.

(Fourth step: Second warm water washing) After the alkali treatment, in order to completely wash away the components eluted in the alkali, the product is washed with warm water. The temperature at this time needs to be 50°C or higher.

At this time, the PO of the waste water is less than 0, or the COD value of the second hot water waste water is less than 50 ppm, or the absorbance of the IC111 cell at 280 nm of the alkaline treated waste water is 0°.
It is preferable to continue until the following values are reached. If this step is incomplete, substances that are soluble under basic conditions and insoluble under acidic conditions will remain in the activated carbon fibers, causing a decrease in performance.

(Fifth step: Acid cleaning) Next, acid cleaning is performed. Here, acid neutralization is performed to neutralize the activated carbon fibers. The acid used here is
Hydrochloric acid or nitric acid is preferable in consideration of the influence on the flavor of foods during use after regeneration and adsorption to activated carbon fibers.

The acid concentration of the cleaning solution is suitably 0.1% by weight or more and 3% by weight or less.

If the concentration of the treatment liquid exceeds 3% by weight, the second
A large amount of washing water is required in the washing process. In addition, if the concentration of the treatment liquid is less than 0.1% by weight, the alkali remaining in the activated carbon fibers after treatment with the alkaline liquid may not be sufficiently removed, or it may take a long time to remove it. Become. A preferable range is 0.2% by weight or more and 1% by weight or less. Activated carbon without acid cleaning! ! If fibers are used for decolorization while still alkaline, there is a high possibility that food products will be recolored after processing, and will also have a strange odor.
It's inconvenient.

The processing temperature is 15℃ or higher and 40℃ considering handling etc.
The following are preferred.

It is desirable to perform acid cleaning until the pl of the acid cleaning waste water becomes 7 or less.

(Sixth step, second water washing) At the end of the regeneration step, water washing is performed. This is done to prevent the acid from the previous step from remaining on the activated carbon fibers. In this case, it is desirable to perform water washing until the pn of the second water washing water becomes 6 or more and 8 or less.

It is desirable that the temperature is 15°C or higher. If the temperature is lower than this, cleaning may be incomplete. The maximum temperature is
It is desirable that the temperature be about the same as when decolorizing foods.

If this step is insufficient, the acid will smell or stick to the treated food, which is inconvenient.

The water and hot water used throughout the entire process of the present invention preferably have a COD of 1 ppm or less and contain few metal ions, so as not to reduce the regeneration effect.

It is desirable that the pH of the water or warm water used in each of steps 1.2.4 and 6 of the present invention is 6 or more and 8 or less, respectively.

Similarly, the alkaline aqueous solution and acid solution used in the third and fifth steps preferably have a COD of 1 ppm or less and contain a small amount of alkali or other ions other than the amount of acid.

Among these ions in water, hot water, aqueous alkaline solutions, or acid solutions, iron ions in particular tend to adhere to activated carbon fibers, and are used in decolorizing foods containing differential ferric rins, such as sake, from activated carbon fibers. Desorbs and colors foods undesirably.

For this reason, it is preferable that the water used throughout the entire process be ion-exchanged so that the iron ion content is 0.1 ppm or less.

The liquid passing rate is the space velocity (packing density of activated carbon fibers 0.1
(When filled to 0.2g/cc or more and 0.2g/cc or less) 20
-100hr' is preferred. When the space velocity is less than 20 hr-1, it takes time to reproduce and the reproduction effect is low. On the other hand, if it exceeds 100 hr', the required amount of liquid to be passed will be excessive, and there is a high possibility that regeneration will be incomplete.

[Example and comparative example]

Below, comparative examples are shown together with examples of the present invention.

Example 1 Polyacrylonitrile activated carbon fiber (specific surface area 1.3
50m'/g, pore volume 1, tcc/g) 2g
was packed into a glass column at a packing density of 0.1.5 g/cc, and using this, the absorbance of Japanese sake [nama sake] at a wavelength of 430 nm in a glass cell with an optical path length of 10 m at a space velocity of 80 hr' was measured. OD 430)-0,02733Q was decolorized.

The oD430 of the processed sake immediately after the start of decolorization is 0004,
The 3Q average 0D430 of sake after decolorization is 0009
Met.

The decolorization rate of sake at this time is 66.7% according to the following formula (1)
was asked.

Decolorization rate (%) - [1 - (average OD'' after treatment, 2) / (oD' before treatment: ): l x 100%... (1) Regeneration was performed under the conditions shown in Table 1. Regeneration The water, hot water, alkaline aqueous solution and acid solution used for
It was prepared based on water obtained by anion-exchanging raw water with a pH of 5 to 72 (measured according to JIS K-0102: atomic absorption method, hereinafter the same applies to iron content). The pH of the water and hot water was 6.5, and the iron content of the water, hot water, alkaline aqueous solution, and acid solution was less than O.ippm. Furthermore, Table 1 shows the properties of the wastewater at the end of each step.

This decolorization-regeneration process was repeated 80 times under the same conditions.

The decolorization rate at the 80th time was 63%, and the performance retention rate at the 80th time was 94.4% [calculated from formula (I) below]. was unnecessary and could be used repeatedly. No fine powder was observed in the sake that was decolorized for the 80th time, and no deterioration of the activated carbon fibers was observed.

80th performance retention rate (%) - 1 @ eye bleaching /80
Second decolorization rate X 100. %... (I[) Table 1 Example 2 Decolorization-regeneration was repeated 80 times under the same conditions as in Example 1, except that the water used in the regeneration step was used as it was without ion exchange. The 80th performance retention rate at this time was 75%.
Met.

Comparative Example From the regeneration conditions of the example, first water washing, first warm washing,
In the case of conditions (A), (B), (C), and (D) in which the second hot washing, acid washing, or second water washing was omitted, and in the case of the condition (E) in which water washing was not performed after acid treatment, the treated sake had an unpleasant odor. It is attached. For the other three conditions (A), (B), and (C), decolorization and regeneration were repeated 40 times.

The 80th performance retention rate at that time is shown in Table 2.

From the results of the Examples and Comparative Examples shown in Table 2 and above, it can be seen that the effects of the present invention are excellent.

[Brief explanation of the drawing]

FIG. 1 shows a regeneration process diagram of the present invention.

Claims (1)

[Scope of Claims] When activated carbon fibers are used to treat and decolorize fermented liquids such as alcoholic beverages and seasoning liquids, or foods such as sugar solutions, or their intermediates, the activated carbon fibers with degraded performance can be used. A method for regenerating activated carbon fibers, which comprises regenerating each of the first to sixth steps shown below in this order. 1st step: Washing with water at a temperature of 35°C or lower. 2nd step: Washing with water at a temperature of 50°C or higher. 3rd step: Treat with an alkaline aqueous solution of 0.1% by weight or more and 4.5% by weight or less at a temperature of 40°C or higher. Step 4: Washing with water at a temperature of 50°C or higher Fifth step: Acid washing step 6th step: Washing with water