JPS6361914B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing an adsorbent for fermented alcoholic beverages comprising silica hydrogel particles having excellent permeability and adsorption properties. Fermented alcoholic beverages such as beer contain components or potential components that inhibit their transparency.
In order to stabilize beer by removing these turbid components or potential components that become turbid during storage,
It is already known to treat beer and the like with bentonite, activated carbon, nylons, polyvinylpyrrolidone, silica gel, etc. to remove these components. Among these adsorbents, silica hydrogel, which has a relatively large specific surface area, has the property of being able to remove turbidity components and potential turbidity components without removing components that help retain foam in beer.
The silica hydrogels conventionally used for this type of application generally have very poor permeability, and have the disadvantage that industrial overtreatment is impossible without the use of a superimposing agent such as diatomaceous earth. As detailed below, the present inventors have discovered that the silica hydrogel obtained by reacting acidic silica sol and sodium silicate in the presence of salts has a combination of excellent adsorbent properties and permeability. They have discovered that they are particularly suitable for use as adsorbents for fermented alcoholic beverages such as beer. That is, an object of the present invention is to provide a method for producing an adsorbent for fermented alcoholic beverages, which is made of silica hydrogel and has an excellent combination of permeability and adsorption properties. Another object of the present invention is to provide a method for producing silica hydrogel having the above-mentioned characteristics efficiently and with good workability. According to the present invention, acidic silica sol and sodium silicate are reacted in the presence of an aqueous salt solution to obtain silica hydrogel particles having a water content of 60 to 90% by weight and a BET specific surface area of 300 m ² /g or more. A method for producing a characterized adsorbent for fermented alcoholic beverages is provided. Although the adsorbent for fermented alcoholic beverages according to the present invention is formed only from silica hydrogel, the primary particle size measured by an electron microscope is 0.1 micron or less, but the secondary particle size measured by the sieving-Coulter counter method is It has a particle size distribution such that particles of 10 microns or more account for 60% or more by weight of the total, and 60 to 90
It has a water content of % by weight, a BET specific surface area of 300 m ² /g or more, and a solubility of 100 ppm or less when measured in an aqueous solution of PH4. A common method for producing silica hydrogels consists of reacting sodium silicate with an acid such as sulfuric acid and gelling the resulting hydrosol. The surface activity of the resulting silica hydrogel is greatly influenced by the pH of the hydrosol; on the acidic side, the surface activity is high, and on the alkaline side, the surface activity tends to be low due to the influence of the residual alkali. From this point of view, silica hydrogel for use as an adsorbent is generally produced by gelling acidic silica hydrosol, but silica hydrogel produced by this method is purified when used as an adsorbent. Separation from fermented alcoholic beverages is quite difficult, and it has the disadvantage that excessive separation is only possible by using a large amount of super-aiding agent such as diatomaceous earth. For this reason, the conventional processing has poor workability, a large amount of slag is formed, and a large amount of slag is retained in the product, and still has many disadvantages in terms of economic efficiency. The reason why silica gel from acidic hydrosol has such poor permanence is that while its surface activity increases,
This is thought to be due to the fact that as the primary particles become finer, the secondary particles also contain considerably finer particles. The present invention is characterized in that a silica hydrogel is produced by reacting acidic silica sol with sodium silicate in the presence of an aqueous salt solution.
That is, the silica hydrogel produced by this reaction is
Although the primary particle size is fine, the secondary particle size during dispersion becomes evenly and uniformly coarse, making it possible to significantly improve the adsorption properties while maintaining the adsorption properties at an excellent level. It is recognized that Such particle size characteristics are thought to be closely related to the reaction mechanism in which a crude acid hydrosol is neutralized with sodium silicate to produce a hydrogel. The acidic silica sol used in the present invention has a pH of 2.5 or less, particularly a pH of 0.3 to 2.0,
It is obtained by reacting sodium silicate with an acid such as sulfuric acid so that the final pH falls within the above range.
As sodium silicate, any composition can be used as long as it satisfies the condition of water solubility, but from the economic point of view, it has the general formula Na ₂ O・nSiO ₂ , where n is 2 to 4. Advantageously, those having a composition with a number of . The acid crude silica sol should be produced at a temperature as low as possible in order to prevent gay formation, and it is generally preferable to carry out the neutralization reaction at a temperature of -10 to +20°C. The _SiO2 concentration in the sol is also related to gelation and is generally
The amount is preferably in the range of 20 to 200 g/, particularly 30 to 150 g/. That is, if the SiO ₂ concentration is higher than the above range, there is a tendency for gelation to occur prior to the reaction of the present invention, while if it is lower than the above range, the concentration is too low and there is a disadvantage that a large amount of liquid must be handled. . The stability of acidic silica sol also changes depending on the pH value, and generally speaking, it is most stable at a pH of about 2, and even if the pH is lower or higher than this, it will not be affected by changes in pH. Stability therefore gradually decreases.
In the present invention, this silica hydrosol is subjected to the reaction with sodium silicate while it is stable. As the sodium silicate to be reacted with the silica sol, sodium silicate having the same composition as that used for producing the silica sol is used. Generally speaking, the SiO ₂ concentration of this sodium silicate aqueous solution is 20 to 300
g/, preferably in the range of 30 to 200 g/. That is, if this concentration is higher than the above range,
It becomes difficult to react uniformly between the two, and it tends to be difficult to obtain a good adsorbent. On the other hand, if it is smaller than the above range, there is a disadvantage that a large amount of liquid must be handled. Acidic silica sol and sodium silicate have a molar ratio of 3:97 to 80:20, especially 20: ₂ , based on SiO2.
It is desirable to carry out the reaction at a molar ratio of 80 to 70:30. That is, at molar ratios other than the above, the reaction tends to be heterogeneous, and especially when the amount of sodium silicate exceeds the above range, the adsorption properties of the resulting hydrogel tend to decrease, while the molar ratio of acidic silica sol If the ratio is larger than the above range, the resulting hydrogel tends to have poor permeability. In the present invention, it is desirable that the acidic silica sol be added to the aqueous sodium silicate solution and the reaction between the two be carried out with stirring. This is because the gradual addition of the acidic sol into the alkaline silicate medium causes the added silica hydrogel to be present in the form of individual particles and with a low water content, rather than in the form of a diellized product throughout. This is because it can be obtained in the form of 60 to 90% by weight. In the present invention, acidic silica sol and sodium silicate are reacted in the presence of salts, but the amount of salts contained in the acidic silica sol, that is, the amount of salts generated by neutralization in the silica sol production step, is generally This is insufficient, and it is necessary to coexist separate salts in the reaction system. It is advantageous to add the salts in advance to the sodium silicate solution used in the reaction, and generally the concentration of the salts in the sodium silicate solution is preferably in the range of 1 to 150 g/. As the salts, water-soluble alkali metal salts of mineral acids such as common salt and mirabilite are used. Although the reaction conditions are not particularly strict, generally a reaction time of 0.5 to 8 hours is used at a temperature of 0 to 90°C. After the reaction is completed, it is also possible to continue aging for about 0.5 to 16 hours for the purpose of homogenizing the particle size. The produced silica hydrogel is over-separated, washed with water and filtered again to obtain an adsorbent product. As is clear from the fact that the silica hydrosol used in the present invention has a primary particle size of 0.1 micron or less as measured by an electron microscope, the primary particle size is extremely fine, yet the secondary particle size is uniform and uniform. It has the characteristic of being coarse. That is, this silica hydrosol has a particle size distribution such that particles having a secondary particle size of 10 microns or more as measured by the sieving-Coulter counter method account for 60% by weight or more, particularly 70% by weight or more of the total. ing. Incidentally, the sieving-Coulter counter method refers to the secondary particle size measurement method described below. In this specification, the reason why the sieving-Coulter counter method is used to measure silica hydrogel is that silica hydrogel particles are bulky and tend to block the measurement tube of the Coulter counter. This is because by subjecting only the particles that have passed through the 325 mesh wire mesh to the Coulter counter measurement, it is possible to more accurately measure the particle size distribution without such troubles. Silica hydrogels particularly suitable for the purposes of the present invention generally have an average secondary particle size (median size) of 5 to 100 microns. Such particle size characteristics provide a significant improvement in perpendicularity without interfering with adsorption properties; for example, the silica hydrogels used in the present invention
It exhibits a permeability that is almost comparable to or even better than diatomaceous earth, which is the most commonly used superadjuvant. Furthermore, the silica hydrogel particles used in the present invention have a water content of 60 to 90% by weight, especially 65 to 80% by weight, and a water content of 300 m ² /g or more, especially 350 to 800 m ² /g.
It has a BET specific surface area of g. This specific surface area is related to the adsorption ability for turbidity components and potential turbidity components in beverages, and it is understood that the silica hydrosol of the present invention has excellent adsorption properties. However, if this specific surface area is too large, it tends to adsorb components that contribute to foam retention and stabilization, so it is preferable that it be 800 m ² /g or less. This adsorption property is also related to the water content in silica hydrogels. In other words, this water content is related to the pore volume of the silica gel structure.
The larger the water content, the larger the pore volume. However, if the water content exceeds the above range, the adsorption performance will decrease due to an increase in the water content that is not related to the adsorption effect, while if the water content falls below the above range, the adsorbed components This is also undesirable since the effective suction seat is reduced. In the present invention, the silica hydrogel has an average pore radius of 40 to 150 Å, measured under the conditions described below. Since the adsorbent used in the present invention is a silica hydrogel having the particle size characteristics described above, it has a solubility of 100 ppm or less when measured in an aqueous solution of PH4. ``For example, when a colloidal sol of silica is used as an adsorption treatment agent, its solubility is 120 to 200 ppm under similar conditions, and the amount of silica dissolved is generally 130 ppm in untreated beer and 130 ppm in wine. In contrast, it can be seen that the amount of silica eluted from the adsorbent of the present invention is extremely small.The adsorbent of the present invention is particularly advantageously used for stabilizing beer. , the adsorbent of the present invention is added to adsorb the turbidity components or their potential components into the gel, and then their removal is carried out by filtration. The present invention will be explained with the following examples: Example 1 A commercially available purified sodium silicate solution (specific gravity 1.31, composition
Add 6.45 kg of water to 4.65 kg (Na ₂ O・2.9SiO ₂・nH ₂ O) to make 10. Add this solution to 8.7 sulfuric acid solution 13, 63 acidic silica sol ( _SiO2 concentration 4.35
g/100ml) was prepared. On the other hand, water and 600 g of common salt were added and dissolved in 4.65 kg of the sodium silicate solution having the above composition to prepare a solution with an SiO ₂ concentration of 7.24 g/100 ml.The solution was poured into a container with an internal volume of 50 ml, and heated to 30 ml with stirring. A previously prepared acidic silica sol was added over a period of about 3 hours to carry out a neutralization reaction while maintaining the temperature at 0.degree. C., thereby obtaining a precipitate of silica hydrogel with good filtration properties. The pH of the reaction solution at the end of this reaction is
It was 6.6. Next, add sulfuric acid solution to this reaction solution.
The pH was adjusted to 1.7, and the temperature was maintained at 30° C. with stirring for 90 minutes of aging. Next, filtration and water washing were repeated three times to obtain a silica hydrogel. The physical properties of this sample were measured and shown in Table 1. Incidentally, each physical property was measured by the following method. 1 Specific surface area Determined by BET method for a product dried at 150°C. 2 Moisture A certain amount of the sample was dried in a constant temperature dryer at 110°C until it reached a constant weight, and the moisture content was determined from the weight loss. (3) The average pore radius of the silica hydrogel was calculated from the following formula. Average pore radius = 2W/S (100-W) x ¹⁰⁴ (Å) W: Water content of hydrogel (%) S: Xerogel BT obtained by drying the hydrogel
Specific surface area (m ² /g) determined from the method The average pore radius of the silica xerogel was determined from the following formula. Average pore radius = 2V/S×10 ⁴ (Å) V: Pore volume determined by nitrogen adsorption (ml/g) S: Specific surface area determined by BET method (m ² /g) (Overspeed) The filtration rate was measured by filtering the silica dispersion using the filtration apparatus shown in Fig. 1. A small filtration speed indicates good filtration properties. Method for measuring filtration rate Add 20 g of silica hydrogel and silica xerogel to 500 ml of water adjusted to pH 4 to 4.5 with hydrochloric acid, sufficiently disperse with a stirrer, and then filter using the filtration device shown in the figure. The speed was measured. 5 After degassing commercially available beer at room temperature, add 1 g of silica (as SiO ₂ ) to 1 beer,
After stirring for 30 minutes, silica was separated by filtration, and the filtered beer was cooled to 0-1°C. Next, a diameter 20 with a gas suction perforated plate at the bottom
After pouring 20ml of beer into a mm glass tube, blow carbon dioxide gas through the perforated plate at the bottom of the glass tube to create bubbles.After making the foam height 20cm, stop blowing carbon dioxide gas and leave it as it is. The disappearance of the bubbles was observed with the naked eye. The same operation was performed three times for each sample to evaluate foam retention. Evaluation of foam retention was indicated by symbols. ○: Excellent foam retention. ×: Poor foam retention. Show that. 6 Particle size Weigh out 50 g of silica hydrogel in a beaker, add 500 ml of water, and disperse it in an ultrasonic disperser for 20 minutes.
The mixture was sieved through a mesh wire sieve and the weight of each was measured. Next, regarding fine particles, the dispersion that passed through a 325-mesh (44μ) sieve was measured using a particle size analyzer model TA-type (measurement device's pore tube 100μ) manufactured by Coulter Counter, USA. Incidentally, silica xerogel was determined in the same manner using 20 g of sample. Example 2 Commercially available purified sodium silicate solution (specific gravity 3.31, composition
Add 6.45 kg of water to 4.65 kg of Na ₂ O・2.9SiO ₂ nH ₂ O)
It was set as 10. This sodium silicate solution has a concentration of 9.1%.
of sulfuric acid solution to prepare an acidic silica sol (silica concentration: 4.6 Å/100 ml) with a pH of 0.55. On the other hand, water and 600 g of salt as salt were added and dissolved in 4.65 kg of sodium silicate solution having the above composition, and the SiO ₂ concentration was
Prepare a solution of 4.6g/100ml 18.74, internal volume 50
The above-prepared acidic silica sol was added over a period of about 3 hours while stirring and heating to 50°C to conduct a neutralization reaction, resulting in the precipitation of a silica hydrogel with excellent filtration properties. . The pH of the reaction solution at the end of this reaction was 69. Next, a sulfuric acid solution was added to this reaction solution to adjust the pH to 1.6, and the temperature was maintained at 50° C. while stirring, and an aging treatment was performed for 90 minutes. Next, repeat filtration and water washing three times,
A silica hydrogel was obtained. The physical properties of this sample were measured and shown in Table 1. Comparative Example Commercially available silica gel A commercially available finely powdered silica gel was used as a sample and its physical properties were measured. This is shown in Table 1. Comparative Example Silica hydrogel by the method of USP 3617301 Commercially available purified sodium silicate (specific gravity 1.40, composition
A sodium silicate solution 2 having a specific gravity of 1.315 was prepared by adding water to Na _{2 O.3.3SiO} 2.nH ₂ O). Meanwhile, water 1280
Add 985g of 98% sulfuric acid to ml, concentration 42.7%, specific gravity
A sulfuric acid solution 1.7 of 1.33 was prepared, poured into a container with an internal volume of 7, and the above sodium silicate solution was added over 5 minutes while maintaining the temperature at 5 to 10°C and stirring at high speed to obtain a uniform silica sol solution. . This silica sol solution had a pH of 0.22 and gelled into a jelly after 5 minutes. Next, the silica hydrogel was aged at room temperature for 6 hours, and then crushed into small pieces and washed with water for 20 hours.
Next, this small-sized silica hydrogel was placed in a pot mill, wet-pulverized using a flint ball, and then filtered to produce a silica hydrogel. The physical properties of this sample were measured and shown in Table 1. 【table】

[Brief explanation of drawings]

FIG. 1 is a schematic layout of the overspeed measuring device used in the example. 1...Stainless steel funnel, 2...Stainless steel wire mesh (diameter 20μ), 3...Stainless steel perforated plate,
4...Rubber stopper, 5...Bottle, 6...Beaker,
7...Glass plate, 8...Kotoku, 9...Mercury manometer, 10...Suction pump.

Claims (1)

[Scope of Claims] 1. Reacting acidic silica sol and sodium silicate in the presence of an aqueous salt solution to obtain silica hydrogel particles having a water content of 60 to 90% by weight and a BET specific surface area of 300 m ² /g or more. A method for producing an adsorbent for fermented alcoholic beverages characterized by: 2. The method according to claim 1, wherein the acidic silica sol has a pH of 2.5 or less. 3. The method according to claim 1, wherein the acidic silica sol and sodium silicate are reacted in a molar ratio of 3:97 to 80:20 based on SiO ₂ . 4. The method according to claim 1, characterized in that the reaction is carried out by adding acidic silica sol to a mother liquor containing sodium silicate and salts.