JP6910136B2 - Adsorbent for purines - Google Patents

Description

The present invention relates to an adsorbent for purines capable of adsorbing purines such as xanthine compounds typified by caffeine, guanine, and compounds containing adenine or guanosine typified by guanosine as constituents.

Currently, caffeine-less beverages are on the market from the viewpoint of health consciousness and the like. This caffeine-less beverage is a beverage obtained by removing caffeine from tea, coffee, or the like. Further, since alcoholic beverages such as beer contain purines that cause gout and the like, alcoholic beverages having a reduced content of these purines are also sold.

By the way, caffeine, xanthine, guanine, guanosine and the like are all compounds having a purine skeleton (collectively, purines). Zeolites, dioctahedral-type smectite-based clays (acidic clay), and the like are known as adsorbents for removing these from beverages (Patent Document 1).

However, zeolite is not used industrially because it has poor selectivity for purines and adsorbs even the active ingredient contained in the beverage.

Further, clays such as acid clay have the advantages of high selective adsorption to purines and low cost, but have a problem of low filterability. That is, a part of this type of clay is colloidally dispersed in water, and the filter is clogged during filtration. If centrifugation is performed without filtration in order to avoid this, loss of the active ingredient will occur and the processing cost will increase.

Further, Patent Document 1 discloses that the activated clay obtained by acid-treating acidic clay has excellent adsorptivity to caffeine (xanthin compound). For example, in its example, the present applicant. The activated clay (Galeon Earth NF-2, Galeonite No. 251 and manufactured by Mizusawa Industrial Chemicals Co., Ltd.) manufactured and sold by Mizusawa Industrial Chemicals Co., Ltd. shows high adsorption to caffeine.

However, as for the adsorptivity to caffeine in Patent Document 1, 40 mg of green tea extract powder (caffeine-containing substance) is dissolved in 5 ml of water, and 1 g of an adsorbent such as activated clay is added to the obtained aqueous solution (100 parts by mass of water). 20 parts by mass per unit) is also added and evaluated. That is, this experiment was carried out by adding a large amount of adsorbent to a paste containing a large amount of caffeine-containing powder, and it cannot be said that the adsorbability to caffeine was properly evaluated. In fact, it is not cost effective to add such a large amount of adsorbent to a beverage to remove caffeine. It is also a problem from the viewpoint of adsorbent separation after treatment. Moreover, the applicant conducted an adsorption test by adding 0.1 g of activated clay (Galleon Earth NF-2, Galeonite No. 251) to 30 g of a 0.2 g / L concentration caffeine aqueous solution according to the actual adsorption treatment. However, it was found that the caffeine adsorption properties of these activated clays (Galeon Earth NF-2, Galeonite No. 251) were significantly inferior to those of acidic clays.

Japanese Patent Application Laid-Open No. 6-142405

Therefore, an object of the present invention is to provide an adsorbent for purines, which has high adsorptivity to purines as high as or higher than that of acidic clay and has excellent filterability.
Another object of the present invention is to provide a method for removing purines contained in an alcohol solution.

The present inventors have conducted many experiments on the adsorption performance of the acid-treated product obtained by the acid treatment of dioctahedral type smectite clay, and as a result of examining it, up to the region called activated clay used for various purposes. Those that have not been acid-treated and have been acid-treated at a weaker level show better adsorption performance than unacid-treated clay (acid clay), and also have excellent filterability, so they are adsorbed. We have found that separation from the later solution can be easily performed, and have completed the present invention.

According to the present invention, it is composed of an acid-treated product of dioctahedral smectite-based clay, and the ratio of the BET specific surface area (A) measured by the water vapor adsorption method to the BET specific surface area (B) measured by the nitrogen adsorption method, ( Provided is an adsorbent for purines, characterized in that A) / (B) is in the range of 1.10 to 5.00.

In the adsorbent of the present invention,
(1) The amount of solid acid with Ho ≦ -3.0 is in the range of 0.10 to 0.70 mmol / g-dry cry.
(2) The value of the BET specific surface area measured by the nitrogen adsorption method is in the range of ^{65 to 400 m 2 / g.}
(3) (A) / (B) is in the range of 1.12 to 2.29,
(4) The purine is a xanthine compound,
(5) The xanthine compound is caffeine,
(6) The purine is an adenine or guanine compound.
Is preferable.

Further, according to the present invention, the adsorbent is placed in an alcohol solution containing a purine body (for example, an alcoholic beverage such as beer or low-malt beer) to adsorb and remove the purine body from the alcohol solution. A method of removing purines is provided.

As shown in Examples described later, the adsorbent of the present invention can remove a large amount of purine from a purine-containing solution equal to or more than that of acid clay by using it in a small amount, for example. The amount of caffeine adsorbed per 1 g of the dried adsorbent is 40 mg or more, particularly 50 mg or more, and the highest performance one shows the amount of caffeine adsorbed at 60 mg or more per 1 g. Further, the amount of guanosine adsorbed per 1 g of the dried adsorbent is 6 mg or more, particularly 10 mg or more, and the highest performance one shows an adsorbed amount of guanosine of 14 mg or more per 1 g.

In addition, the adsorbent of the present invention has higher filterability than acid clay, and can be easily removed from the solution after the adsorption treatment.

Therefore, the adsorbent of the present invention has high adsorptivity to purines, is suitably applied to the production of caffeine-less beverages by removing caffeine from beverages such as tea and coffee, and further, alcoholic beverages such as beer. It can also be applied to the removal of purines from.
Since the adsorbent of the present invention is composed of an acid-treated product of dioctahedral type smectite-based clay, it contains leaching Na ions as compared with conventionally known smectite-based clay that has not been subjected to acid treatment. , Ca ions are suppressed to a low level, and the generation of precipitates such as Ca oxalate can be suppressed, and the influence on the color and flavor of the beverage can be suppressed.

6 is an X-ray diffraction chart derived from the surface index (06) of the adsorbent (weak acid-treated white clay) of the present invention used in Example 1.

<Weak acid treated white clay>
The adsorbent of the present invention is composed of an acid-treated product of dioctahedral type smectite clay, but it is obtained by a weak acid treatment as compared with what is generally called active clay, and should be called a weak acid-treated clay. Is. Therefore, hereinafter, the acid-treated product used as an adsorbent for purines may be referred to as "weak acid-treated white clay".
For example, Japanese Patent Application Laid-Open No. 2009-072759 by the present applicant discloses that an acid-treated product called semi-active clay obtained by acid-treating dioctahedral clay is used as a catalyst for polylactic acid depolymerization. The weak acid-treated clay used in the present invention is obtained by a weaker acid treatment than this semi-active clay.

The weak acid-treated white clay used as an adsorbent in the present invention has a very low acid treatment level of dioctahedral smectite-based clay, and is therefore measured by the BET specific surface area (A) measured by the steam adsorption method and the nitrogen adsorption method. the ratio of the BET specific surface area (B) (a) / ( B) is 1.10 or more in terms of adsorption properties, is preferably 1.20 or more. The upper limit of (A) / (B) is 5.00 or less, but from the viewpoint of filterability, it is preferably 4.20 or less, particularly preferably 3.30 or less, and most preferably 2.80 or less. ..

It is presumed that such a weak acid-treated white clay can exhibit excellent adsorption performance for purines by having a BET specific surface area ratio (A / B) in the above range.
That is, as a method for measuring the BET specific surface area, a method using nitrogen (nitrogen method) is common, but there is also a method for measuring using water vapor (water vapor method). According to the Clay Handbook (3rd edition), the nitrogen method measures the total external surface area including the end face per unit mass, and in the case of dioctahedral smectite clay that has a three-layer structure, the nitrogen molecule is liquid nitrogen. Only the external surface area is measured as it does not penetrate between layers at temperature. On the other hand, in the water vapor method using a polar adsorbent such as water vapor, the adsorbent sufficiently penetrates between the layers of the clay, so that the internal surface is measured. Therefore, the fact that A / B is within the above range means that the micropores are increased by the very weak acid treatment, and the layers of the basic three layers of the smectite clay are expanded. Increased micropores improve selective adsorptivity to purines (especially xanthine compounds such as caffeine), and expansion between the layers of the basic three layers provides moderate surface hydrophilicity for purines in aqueous and alcohol solutions. Increases adsorptivity. The adsorbent of the present invention (weak acid-treated white clay) having the above A / B value is a purine body because an appropriate expansion between the layers of the basic three layers and the formation of micropores within the layers occur in a well-balanced manner in the acid treatment step. It is believed that it exhibits extremely high selective adsorption.
For example, in the conventionally known activated clay or semi-active clay obtained by treating with a strong acid, the spread between the layers of the basic three layers becomes large, and the micropores formed between the layers are crushed. Therefore, the value of A / B becomes small, and therefore the purine adsorption property becomes extremely low.

Further, it is presumed that the weak acid-treated white clay has excellent filterability because it has been subjected to the acid treatment.
Smectite clay (acidic clay) that has not been treated with acid has a large layer containing cations such as Na between the basic layers, so it exhibits high swelling property with respect to water and is finely dispersed by swelling. It is considered that the filterability is poor due to the conversion. In the case of such a weak acid-treated clay, a part of the base component in the smectite clay reacts with the acid and becomes a kind of insoluble binder for water, alcohol, etc., so that the particles are bonded to each other in the solution. It is considered that the microdispersion of clay is suppressed and excellent filterability is exhibited.
Therefore, the weaker the degree of acid treatment, the larger the A / B, which may impair the filterability.

Since the weak acid-treated clay used as an adsorbent in the present invention is obtained by a weak acid treatment as compared with what is generally called active clay, Na content and Ca covering Al and Mg acting as solid acid points The amount is removed, and the decrease in the amount of solid acid due to the elution of Al and Mg with the progress of the acid treatment is suppressed. As a result, the amount of solid acid is equal to or higher than that obtained by conventional acid treatment, which is generally called active clay, or acid clay not subjected to acid treatment. The weak acid-treated white clay preferably has a solid acid amount of Ho ≦ -3.0 in the range of 0.10 to 0.70 mmol / g-dry layer, which means that it contains a large amount of relatively strong solid acid. ing. That is, the chemical adsorption performance of the solid acid to the purine body is enhanced, and as shown in Examples described later, when used in a small amount, it is equivalent to or equivalent to the conventionally known active clay or acidic clay. More than that, more purines can be removed from the purine-containing solution.

Further, since the weak acid-treated clay used as the adsorbent in the present invention is weakly acid-treated, the BET specific surface area by the nitrogen method is improved as compared with the smectite-based clay not subjected to the acid treatment. It is preferably in the range of 65 to 400 m ² / g, and particularly preferably in the range of ^{100 to 400 m 2 / g.} However, the weak acid-treated clay has a lower BET specific surface area ratio (A / B) than the smectite-based clay not subjected to the acid treatment, but is considered to exhibit high adsorptivity.

Furthermore, the above-mentioned weak acid-treated clay shows a peculiar X-ray diffraction peak derived from the crystal structure of the dioctahedral type smectite clay, and for example, in the X-ray diffraction measurement, the diffraction peak derived from the plane index (06) is 2θ. It is held near = 62 degrees (d = 1.49 to 1.50 Å).

<Manufacturing of weak acid-treated white clay>
The weak acid-treated clay having the above-mentioned characteristics is produced by coarsely crushing and kneading dioctahedral type smectite clay and acid-treating it with an acid aqueous solution having a predetermined concentration under predetermined conditions. That is, this weak acid-treated clay is obtained in the same manner as the semi-active clay, but is obtained by acid treatment under mild conditions as compared with the semi-active clay.

The dioctahedral smectite clay used as the raw material clay is thought to be a metamorphic transformation of volcanic rocks and lava under the influence of seawater, and the dioctahedral smectite, which is the main component, is the SiO ₄ tetrahedral layer-AlO ₆ octahedral layer-. consists SiO ₄ tetrahedral layers, and has these tetrahedral layer and the octahedral layer is partially different metals in isomorphous-substituted three-layer structure the basic structure (unit layer), stacked in such a three-layer structure Between the layers, there are cations such as Ca, K, and Na, hydrogen ions, and water molecules coordinating with them. Further, since Mg and Fe (II) are substituted in a part of Al in the octahedral layer of the basic three-layer structure and Al is substituted in a part of Si in the tetrahedral layer, the crystal lattice is negative. It has an electric charge, and this negative charge is neutralized by metal cations and hydrogen ions existing between the basic layers. Such smectite clays include acidic clay, bentonite, fraze earth, etc., and exhibit different characteristics depending on the type and amount of metal cations existing between the basic layers, the amount of hydrogen ions, and the like. For example, in bentonite, the amount of Na ions present between the basic layers is large, so that the pH of the dispersion liquid suspended and dispersed in water is high, generally on the highly alkaline side, and has high swelling property with respect to water. In addition, it exhibits the property of gelling and solidifying. On the other hand, in acidic clay, the amount of hydrogen ions present between the basic layers is large, and therefore the pH of the dispersion liquid suspended and dispersed in water is low, generally on the acidic side, and exhibits swelling property with respect to water. However, as compared with bentonite, its swelling property is generally low, and gelation does not occur.

In the present invention, the dioctahedral type smectite clay used for producing the weak acid-treated clay is not particularly limited, and any of the above-mentioned types can be used. Further, such raw material clay has the following composition in terms of oxide, although it differs depending on the origin of the clay, the place of origin, and the place of burial (face) even in the same place of origin.
SiO ₂ ; 50 to 75% by mass
Al ₂ O ₃ ; 11-25% by mass
Fe ₂ O ₃ ; 2 to 20% by mass
MgO; 2-7% by mass
CaO; 0.1 to 3% by mass
Na ₂ O; 0.1 to 3% by mass
K ₂ O; 0.1 to 3% by mass
Other oxides (TiO _2, etc.); 2% by mass or less Ig-loss (1050 ° C.); 5-11% by mass

In addition, the raw material clay may contain a large amount of impurities such as quartz depending on the production area and the like. Therefore, it is preferable to apply the above dioctahedral type smectite clay to refining operations such as stone sand separation, buoyancy beneficiation, magnetic beneficiation, elutriation, and elutriation to remove impurities as much as possible, and then perform acid treatment. After performing such a treatment, a weak acid-treated white clay having an A / B within the above range can be obtained by performing an acid treatment under the mild conditions described below.

The acid treatment is carried out by putting the raw material clay into the acid aqueous solution, mixing and stirring. The acid aqueous solution used for the acid treatment is not particularly limited, but a sulfuric acid aqueous solution is generally used from the viewpoint of cost, environmental impact and the like.

Further, as described above, such acid treatment is carried out under mild conditions as compared with the acid treatment for producing conventionally known active clay or semi-active clay, for example, when an aqueous sulfuric acid solution is used. The amount of sulfuric acid aqueous solution calculated assuming that the water content in the raw material clay also constitutes the sulfuric acid aqueous solution is 250 to 800 parts by mass per 100 parts by mass of the raw material clay (as a dried product at 110 ° C.), and the concentration of the sulfuric acid aqueous solution at that time is 1. The acid treatment may be performed under conditions such that the content is about 15% by mass. In the acid treatment, it can be heated to about 25 to 95 ° C. if necessary. In this way, the specific surface area ratio (A / B) is within a predetermined range (about 0.5 to 12 hours, preferably 0) depending on the composition of the raw material, the acid concentration of the acid aqueous solution used, the treatment temperature, and the like. The acid treatment may be carried out for about 5 to 8 hours, particularly preferably about 0.5 to 4 hours).

By the acid treatment as described above, the ratio A / B of the BET specific surface area by the nitrogen method to the BET specific surface area by the steam method, the amount of solid acid, and the value of the BET specific surface area by the nitrogen method are in the above ranges, and adsorption to the purine body. The adsorbent of the present invention (weak acid-treated white clay) having excellent performance can be obtained.

Further, the weak acid-treated white clay obtained by the above-mentioned acid treatment generally has the following chemical composition in terms of oxide.
SiO ₂ ; 50 to 85% by mass
Al ₂ O ₃ ; 8-23% by mass
Fe ₂ O ₃ ; 1 to 10% by mass MgO; 1 to 5% by mass CaO _{; 0.1 to 2} % by mass Na 2 O; 0.1 to 1% by mass
K ₂ O; 0.1 to 1% by mass
Other oxides (TiO _2, etc.); 2% by mass or less Ig-loss (1050 ° C.); 4-9% by mass

<Purine body>
In the present invention, the above-mentioned weak acid-treated white clay exhibits excellent selective adsorption property for purines, that is, compounds having a purine skeleton.

で表され、弱酸処理白土は、上記のようなプリン骨格を有する化合物、即ち、部分構造としてプリン骨格を有する化合物、及び、かかる化合物の誘導体もしくはかかる化合物から派生する化合物に対して優れた選択的吸着性を示す。 The purine skeleton is expressed by the following formula:

The weak acid-treated white clay is excellently selective for a compound having a purine skeleton as described above, that is, a compound having a purine skeleton as a partial structure, and a derivative of such a compound or a compound derived from such a compound. Shows adsorptivity.

で表されるキサンチンの他、ヒポキサンチンを挙げることができる。 As one of the purine bodies, the following formula:

In addition to xanthine represented by, hypoxanthine can be mentioned.

で表されるカフェインを挙げることができる。即ち、カフェインは、キサンチンの３つのＮＨ基が全てメチル化されてＮＣＨ_３基となった、キサンチン誘導体である。
カフェイン以外のキサンチン誘導体としては、これに限定されるものではないが、テオフィリン、テオブロミン、パラキサンチン等を挙げることができる。
キサンチン、ヒポキサンチンおよびキサンチンから派生する化合物を、本明細書では、総じてキサンチン化合物とする。本発明の吸着剤は、キサンチン化合物に対して優れた選択吸着性を示し、キサンチン化合物用吸着剤として好適であり、カフェイン用吸着剤として特に好適である。 Further, as a compound derived from xanthine, the following formula:

Caffeine represented by can be mentioned. That is, caffeine is a xanthine derivative in which all three NH groups of xanthine are methylated _{to become three NCH groups.}
Examples of the xanthine derivative other than caffeine include, but are not limited to, theophylline, theobromine, paraxanthine and the like.
Xanthine, hypoxanthine and compounds derived from xanthine are collectively referred to herein as xanthine compounds. The adsorbent of the present invention exhibits excellent selective adsorptivity for xanthine compounds, is suitable as an adsorbent for xanthine compounds, and is particularly suitable as an adsorbent for caffeine.

There are also adenine and guanine as purines. Examples of compounds derived from adenine or guanine include purine nucleosides (adenine and guanosine) composed of adenine or guanine and ribose, and purine nucleotides (adenylic acid and guanylic acid) containing phosphoric acid as a constituent. In addition, examples of other organic compounds derived from adenine or guanine include, but are not limited to, deoxyguanosine, deoxyguanosine triphosphate, nicotinamide adenine dinucleotide (NAD), and flavin adenine dinucleotide (FAD). , Inosine, inosinic acid and the like. In the present specification, the above-mentioned adenine or guanine and a compound derived from adenine or guanine are collectively referred to as an adenine or guanine compound. The adsorbent of the present invention exhibits selective adsorptivity to adenine and guanine, and therefore also exhibits excellent selective adsorptivity to adenine or guanine compounds, and is suitable as an adsorbent for such compounds. In the examples described later, the adsorbent of the present invention exhibits excellent selective adsorptivity to guanine and guanosine, which is a nucleoside in which a _{ribose ring is composed of a β-N 9-glycosidic bond to guanine.}

<Use>
The weakly acid-treated white clay used as an adsorbent in the present invention is not only excellent in selective adsorption to purines, but also requires a small amount of use, so that the elution of metals that may affect the flavor of beverages is small, and therefore, tea and It is preferably used to remove caffeine from beverages such as coffee to make it caffeine-less, and is also used as an adsorbent for removing purines from alcoholic beverages such as beer. For example, it is used by adding it to the above-mentioned solution in which the purine body is dissolved in an amount of 0.001 to 10 parts by mass.
In order to remove caffeine and the like from these beverages, the above-mentioned weak acid-treated white clay may be adjusted in particle size into a powder having an appropriate average particle size (for example, about 10 to 300 μm) and mixed with the beverage.
In addition to the above beverages, the adsorbent for purines of the present invention is used in solid-liquid separation (filtration) during the manufacturing process of foods including various seasonings and supplements, and various chemicals used in industry and agriculture. It can be applied to beverages without any limitation by appropriately adjusting the particle size to be suitable in the process used.
In addition, the adsorbent of the present invention can be applied to the fields of medicine such as drug discovery and pharmaceuticals by utilizing the selective adsorptivity and filterability of an adenine or guanine compound.
The adsorbent of the present invention is particularly preferably applied to the fields of beverages and foods.

As shown in Examples described later, the adsorbent of the present invention can adsorb and remove purines in an alcohol solution containing purines. Therefore, for example, purines such as beer and low-malt beer can be used. Purines can be preferably removed from alcoholic beverages and the like.
The alcohol solution means a liquid containing alcohol, and may contain, for example, water or the like in addition to alcohol. Specifically, fermented malt beverages such as beer and sparkling liquor, beer-taste beverages, liquor, wine, brewed alcohol, shochu, spirits, liqueurs, whiskey, brandy, sake, fruit liquor, liquor high, cocktails and other beverages. In addition to those provided for use, various alcohol-containing products provided for food, industrial, agricultural, and medical purposes, raw materials used in the manufacturing process thereof, and the like can be mentioned. The alcohol is not particularly limited, and is, for example, methanol, ethanol, lower alcohol (for example, 2-propanol, ethylene glycol, glycerin, etc.), higher alcohol (aliphatic alcohol having 8 to 22 or more carbon atoms, for example, capryl alcohol, lauryl alcohol, etc.). , Myristyl alcohol, cetyl alcohol, stearyl alcohol, oleyl alcohol, linolyl alcohol, etc.), phenol, aromatic alcohol and the like, preferably ethanol. The concentration of alcohol is not particularly limited, and can be applied to a solution containing at least one of the above alcohols. By applying the above-mentioned adsorbent of the present invention to an alcohol solution, purines can be suitably removed from the above-mentioned alcohol-containing products and raw materials used in the manufacturing process thereof.

The weak acid-treated white clay used as an adsorbent in the present invention has a feature that the BET specific surface area is increased by the acid treatment and a large amount of a relatively strong solid acid is contained. Therefore, the adsorbent of the present invention can be used without any limitation for decolorization of fats and oils and mineral oils, catalysts or catalyst carriers, as in the case of conventional activated clay.

Since the weak acid-treated white clay adsorbed with caffeine or the like has excellent filterability, it can be easily separated by filtering by a method known per se, which is a great advantage of the present invention. That is, it can be separated by centrifugation or the like, but in such a method, the active ingredient in the beverage is also removed, but by filtration, such an inconvenience can be effectively avoided.

The excellent effect of the present invention will be described with reference to the following experimental examples.

(1) BET specific surface area (B) by nitrogen adsorption method
The measurement was carried out by the nitrogen adsorption method using TriStar 3000 manufactured by Micromeritics, and the measurement was performed by the BET method. The pretreatment was carried out at 150 ° C. for 2 hours.

(2) BET specific surface area (A) by water vapor adsorption method
The measurement was performed by the steam adsorption method using BELSORP MAX manufactured by Nippon Bell Co., Ltd., and calculated by the BET method. The pretreatment was carried out at 150 ° C. for 2 hours.

(3) pH
The adsorbent powder was added to the ion-exchanged water so that the adsorbent concentration was 2% by mass, and the mixture was stirred for 30 minutes and then measured with a pH meter HM-30R manufactured by Toa DKK.

(4) Amount of solid acid The amount of solid acid with Ho ≦ -3.0 was measured by the n-butylamine titration method. The sample was measured in advance by drying it at 150 ° C. for 3 hours. {Reference: "Catalyst" Vol. 11, No6, P210-216 (1969)}.

(5) Caffeine Adsorption Test The caffeine adsorption capacity in this example is the amount of caffeine (mg) capable of adsorbing 1 g of an adsorbent (anhydrous) from a 0.2 g / L concentration caffeine aqueous solution, as described below. Was measured and calculated.
First, anhydrous caffeine (special grade reagent, manufactured by Wako Pure Chemical Industries, Ltd.) was dissolved in ion-exchanged water to obtain a 0.2 g / L concentration caffeine aqueous solution.
30 g of this 0.2 g / L concentration caffeine aqueous solution is weighed in a 50 ml volume centrifuge tube, 0.1 g of an adsorbent (0.33% by mass with respect to the liquid) is added, and a shaker (manufactured by Yamato Scientific Co., Ltd.) It was shaken for 2.5 hours by SA300 and shaking speed 5).
Next, the supernatant of the liquid treated with a centrifuge (5200 manufactured by Kubota Co., Ltd.) at a centrifugal acceleration of 3000 rpm for 20 minutes was diluted 10-fold with ion-exchanged water to obtain a liquid (sample liquid). The absorbance of the 273 nm wavelength light of the sample solution was measured with a spectrophotometer (V-630 manufactured by JASCO Corporation). Then, the residual amount of caffeine in the sample solution was calculated using a calibration curve showing the relationship between the caffeine concentration prepared in advance and the absorbance of 273 nm wavelength light, and the value subtracted from the amount of caffeine before the addition of the adsorbent was subtracted from the adsorbent. The amount of caffeine adsorbed was used.

(6) Filtration test 200 ml of green tea (commercially available) was placed in a beaker, 5 g of adsorbent powder dried at 110 ° C. for 1 hour was placed therein, and the mixture was stirred with a stirrer for 5 minutes. A filter paper (ADVANTEC No. 2) was set in a stainless steel Buchner funnel (filtration area 38.5 cm ^{2), and the vacuum pump was switched on.} The adsorbent powder dispersion was poured into the funnel, the suction pressure was adjusted to 20 cmHg, and when the amount of the filtrate reached 100 ml, the stopwatch was started. The suction pressure was maintained at 20 cmHg during filtration. The stopwatch was stopped when the amount of the filtrate reached 150 ml, and this time was taken as the filtration time.

(7) X-ray diffraction Measurement was performed by RINT-Ultima IV (X-ray = CuKα-ray) manufactured by Rigaku Co., Ltd.

(8) Guanosine Adsorption Test The guanosine adsorption capacity in this example is calculated by measuring the amount of guanosine (mg) capable of adsorbing 1 g of a sample (anhydrous) from a 0.2 g / L aqueous solution of guanosine. did.
First, guanosine (manufactured by Alfa Aesar) was dissolved in 1 L of ion-exchanged water to obtain a guanosine aqueous solution having a concentration of 0.2 g / L.
35 g of this 0.2 g / L concentration guanosine aqueous solution is weighed in a 50 ml volume centrifuge tube, 0.5 g (1.4% by mass of liquid) of test powder is added, and a shaker (manufactured by Yamato Scientific Co., Ltd.) It was shaken for 0.5 hours by SA300 and shaking speed 5).
Next, the treatment was carried out with a centrifuge (5200 manufactured by Kubota Co., Ltd.) at a rotation speed of 3000 rpm for 30 minutes, and the supernatant of the liquid was diluted 10-fold with ion-exchanged water to obtain a liquid (sample liquid). The absorbance of the 260 nm wavelength light of the sample solution was measured with a spectrophotometer (V-630 manufactured by JASCO Corporation). Then, the guanosine concentration of the sample solution was calculated using a calibration curve showing the relationship between the guanosine concentration prepared in advance and the absorbance of the 260 nm wavelength light. From this value, the amount of guanosine adsorbed per unit amount of sample was calculated.

(9) Guanine Adsorption Test The guanine adsorption capacity in this example was evaluated using the degree of decrease in the absorbance of 248 nm wavelength light when a predetermined amount of test powder was added to a saturated aqueous solution of guanine for treatment.
First, 0.05 g of guanine (special grade reagent, manufactured by Wako Pure Chemical Industries, Ltd.) was added to 1 L of ion-exchanged water, stirred overnight at room temperature, and then filtered through filter paper (No. 5C manufactured by ADVANTEC). The undissolved guanine was removed and used as a saturated aqueous solution of guanine.
0.02 g (0.02% by mass with respect to the liquid) of the test powder was added to 100 g of this saturated guanine aqueous solution, and the mixture was stirred with a magnetic stirrer for 3 hours. Next, the absorbance of the 248 nm wavelength light of the liquid (sample liquid) filtered through the filter paper (No. 5C manufactured by ADVANTEC) was measured with a spectrophotometer (V-630 manufactured by JASCO Corporation). At this time, in order to subtract the influence of water-soluble salts of the test powder, the absorbance when 0.02 g of the test powder is added to 100 g of ion-exchanged water in which guanine is not dissolved in advance and the same operation is performed is subtracted from the absorbance of the sample solution. , The corrected absorbance of the sample solution was used. The value obtained by converting the ratio of the absorbance of the saturated guanine aqueous solution to the value obtained by subtracting the corrected absorbance of the sample solution from the absorbance of the saturated guanine aqueous solution into 100% was defined as the guanine adsorption capacity (%) of the test powder.

(10) Guanosin adsorption test in alcohol solution (8) The solvent of the 0.2 g / L concentration guanosine aqueous solution used in the guanosine adsorption test was changed from ion-exchanged water to a 5% by volume ethanol aqueous solution, and the centrifugation treatment was performed on filter paper (10). The amount of guanosine adsorbed in the alcohol solution was calculated by the same operation as in (8) guanosine adsorption test, except that the solid-liquid separation treatment was performed by ADVANTEC No. 5C).

For the adsorbent powders shown in the following Examples and Comparative Examples, the physical characteristics and various adsorption test results are shown in Tables 1 and 2, and the filtration test results are shown in Table 3.

(Comparative Example 1)
Dioctahedral type smectite clay produced in Tainai City, Niigata Prefecture was coarsely crushed, dried (110 ° C.), crushed, and classified to obtain an adsorbent powder.

(Example 1)
220 ml of a 10 mass% sulfuric acid aqueous solution was placed in a beaker and heated to 90 ° C. 30 g of the adsorbent powder obtained in Comparative Example 1 was added thereto, the mixture was stirred while the liquid temperature was maintained at 90 ° C., and acid treatment was performed for 30 minutes. After completion of the acid treatment, the acid-treated product was filtered and washed with water, and the washed filtered cake was dried at 110 ° C., pulverized and classified to obtain a weak acid-treated white clay powder. The obtained weak acid-treated white clay powder was measured by an XRD measuring device. The X-ray diffraction chart is shown in FIG.

(Comparative Example 2)
Dioctahedral type smectite clay produced in Shibata City, Niigata Prefecture was purified by elutriation, dried (110 ° C.), pulverized, and classified to obtain an adsorbent powder.

(Example 2)
The adsorbent powder in Example 1 was changed to the adsorbent powder obtained in Comparative Example 2, and the acid treatment time was changed to 1 hour to obtain a weak acid-treated white clay powder.

(Example 3)
The concentration of the sulfuric acid aqueous solution in Example 2 was changed to 5% by mass to obtain a weak acid-treated white clay powder.

(Example 4)
The heating temperature in Example 3 was changed to 25 ° C. to obtain a weak acid-treated white clay powder.

(Example 5)
The acid treatment time in Example 3 was changed to 4 hours to obtain a weak acid-treated white clay powder.

(Example 6)
Dioctahedral type smectite clay from Aga Town, Niigata Prefecture was refined with elutriation, dried (110 ° C), crushed, and classified to obtain clay powder. The pH of this clay powder was 9.5.
The adsorbent powder in Example 5 was changed to this clay powder, the concentration of the sulfuric acid aqueous solution was changed to 11% by mass, and a weak acid-treated white clay was obtained.

(Comparative Example 3)
Activated clay galleon earth NF-2 manufactured by Mizusawa Industrial Chemicals Co., Ltd.

(Comparative Example 4)
Active clay galeonite No. manufactured by Mizusawa Industrial Chemicals Co., Ltd. 251.

(Comparative Example 5)
Activated clay galleon earth V2 manufactured by Mizusawa Industrial Chemicals Co., Ltd.

(Comparative Example 6)
Mizusawa Industrial Chemicals Co., Ltd.'s Acid Clay Mizuka Ace No. 20.

(Comparative Example 7)
Dioctahedral type smectite clay produced in Aga Town, Niigata Prefecture was dried (110 ° C.), pulverized, and classified to obtain an adsorbent powder.

(Example 7)
The adsorbent powder in Example 1 was changed to the adsorbent powder obtained in Comparative Example 7, and the concentration of the sulfuric acid aqueous solution was changed to 5% by mass to obtain a weak acid-treated white clay.

(Example 8)
The acid treatment time in Example 1 was changed to 2 hours to obtain a weak acid-treated white clay powder.

(Example 9)
The concentration of the sulfuric acid aqueous solution in Example 4 was changed to 2% by mass, the acid treatment time was changed to 0.5 hours, and a weak acid-treated white clay powder was obtained.

尚、吸着試験後の比較例２の吸着剤粉末は、固液分離困難な状態であり、明らかに濾過性に劣っていた。 (Reference experiment)
Natural Spanish site.

The adsorbent powder of Comparative Example 2 after the adsorption test was in a state where solid-liquid separation was difficult, and was clearly inferior in filterability.

Claims (8)

It consists of an acid-treated dioctahedral type smectite clay.
The ratio of the BET specific surface area (A) measured by the water vapor adsorption method to the BET specific surface area (B) measured by the nitrogen adsorption method, (A) / (B), is in the range of 1.10 to 5.00. An adsorbent for purines, which is characterized by this. The adsorbent according to claim 1, wherein the amount of solid acid in Ho ≦ −3.0 is in the range of 0.10 to 0.70 mmol / g-dry cry. The adsorbent according to claim 1 or 2, wherein the value of the BET specific surface area measured by the nitrogen adsorption method ^{is in the range of 65 to 400 m 2 / g.} The adsorbent according to any one of claims 1 to 3, wherein (A) / (B) is in the range of 1.12 to 2.29. The adsorbent according to any one of claims 1 to 4, wherein the purine compound is a xanthine compound. The adsorbent according to claim 5, wherein the xanthine compound is caffeine. The adsorbent according to any one of claims 1 to 4, wherein the purine is an adenine or a guanine compound. A method for removing a purine from an alcohol solution, which comprises putting the adsorbent according to any one of claims 1 to 7 into an alcohol solution containing a purine and adsorbing and removing the purine.

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