DE3015439C2 - Use of activated carbon granules which disintegrate in an aqueous system - Google Patents

Description

The present invention relates to the use of activated carbon granules, which when wetted with Disintegrate spontaneously in water or in an aqueous system.

The treatment of liquids with activated carbon is carried out to remove unwanted components remove, e.g. B. those that cause annoying discoloration or unpleasant smell or taste impressions cause. In this context, the treatment of technical issues is of particular importance Solutions of various sugars and their conversion products as well as wine, beer, spirits and Obtained fruit juices with activated charcoal.

Activated carbon is z. B. used to decolorize red wines or to remove unwanted colorings from high-color and dark wines. Because of its good adsorption capacity, it can also be used in wine disruptive flavors and odors, such as cork and barrel flavors, mold and yeast smells, removed will.

In the past, grained charcoal and animal charcoal with little pronounced adsorptive capacity were often used today, very finely ground, high-performance activated carbons are almost exclusively used in the stirring process applied. Unfortunately, these activated carbons have a number of important application-technical aspects 3fr cons.

The tendency of the finely ground high-performance carbons to form a lot of dust, especially, is extremely annoying in pharmaceutical and beverage technology. Furthermore, the poor wettability of the irydrophobic activated carbon causes difficulties when stirring into the liquid phase and when mixing. The sedimentation behavior and the filterability of the stirred in are also of great importance Activated carbon. The aim is for the powdered charcoal to be as much as possible after an exact contact time with the liquid snow! and completely sedimented. Delayed sedimentation means uncontrolled action on the Aromas and flavors of the drink and clogging of the filters when filtering.

Granular activated carbon can be used to avoid the disadvantages of powdered activated carbon, but then has a less favorable kinetic behavior and possibly less favorable equilibrium positions -IO or higher prices to be accepted.

The aim of the present invention is therefore to find an activated carbon with a large adsorption effect, which does not dust, becomes easily wettable through hydrophilization with water, in liquids, water or beverages immediately disintegrates and has a favorable sedimentation behavior.

The present invention therefore relates to the use of activated carbon granules containing them Powdered activated carbon, silica sol and optionally water and auxiliaries, the SiOr content of the activated carbon granules 1 to 20% by weight, based on the dry matter, for cleaning liquids.

There has been no lack of attempts to granulate finely ground powdered coals with suitable binders. Apart from the fact that technical disadvantages occur with the vast majority of binders, in the case of Intended use in beverages also includes the aspect of harmlessness to health get noticed. So only binders that are harmless to health are to be used are or already for beverage treatment due to their harmlessness to health and suitability as an auxiliary material allowed are.

Inorganic and organic binders that can contaminate the drink due to their solubility, are to be excluded from the outset as unsuitable. Other insoluble binders, in turn, bind the!

Aktivkohlepartikcl irreversibly with each other, so that their adsorption capacity is greatly reduced and a jj

The granules in the drink no longer disintegrate. It is known. Activated carbon using bentonite. a swellable aluminum silicate, to be granulated, although considerable amounts of bentonite 10% and more - must be built into the end product.

It has now surprisingly been found that finely ground, powdery activated carbon can be granulated particularly well with an OO silicate binder, the desired hydrophilization and the associated easy wettability by the aqueous liquid to be treated occurring. It is particularly surprising that the sufficiently abrasion-resistant granules after Wetting in the aqueous medium disintegrates immediately, | although it is known on the other hand that soluble alkali metal silicates, such as water glass, hard the Aktivkohe ^s naked bond. g The silicate binder, which is suitable for granulating powdered activated carbon, is technically pure silica sol, as it is approved for the treatment of wine by the German Wine Ordinance of July 15, 1971, for example.
The products understood according to the invention under silica sol are colloidal solutions of amorphous silicon

cium dioxide in water, which can also be referred to as silicon dioxide aquasols or silicic acid aquasols. The silicon dioxide is in the form of spherical particles that are hydroxylated on the surface before. The particle size of the colloid particles is approx. 2-100 μm, the specific one correlating to the particle size Surface area is approx. 50-600 nr / g according to BET and expresses the surface area 1 g of dried silicon dioxide from which Aquasol would develop.

Various processes for producing such silica sols are known. Silica sols are commercially available as weakly alkaline or weakly acidic solutions in 30% concentration (stated as% by weight), but it is easily possible to produce concentrations _{between 15 and 60% SiO 2.}

Silica sols develop their binding effect either by adding gelling agents or by The drying process is transformed into silica gels with spatial crosslinking. Such silica gels make solid amorphous Silicon dioxide is, for example, by the EEC Regulation No. 1678/77 of July 19, 1977 for the Treatment of wine allowed and approved by the EEC Directive of November 17, 1975 for the treatment of Fruit juice is suggested. Furthermore, the use of silica gels for the removal of cold-labile Proteins from beers allowed

According to the German Offenlegungsschrift 16 67 436, solid, water-insoluble silica gels are already known, which contain small amounts of activated carbon built in to increase their adsorption capacity. The goal of this The patent specification does not lie in the granulation of activated carbon, but rather products are stored with it Get activated carbon, which means that the activated carbon is firmly anchored and glued by the silica gel is. These products do not disintegrate when wetted with water.

By adding gravel sols and water to the above-mentioned high-performance Powdered charcoal is obtained a mass capable of being granulated, which can be used in the technical equipment customary for this purpose Granules can be deformed with sufficiently good green stability. After drying will be receive sufficiently abrasion-resistant and easily manageable granules.

In order to obtain activated carbon granules for the purposes of the present invention, which after wetting with the to liquid to be treated disintegrate spontaneously, it has proven to be advantageous to use so much silica sol that the dried end product has a silicon dioxide content of at least 1-20%. In addition, it is however, it is possible to modify the carbon by adding more silica sol.

Particularly excellent granules within the meaning of the invention, which are sufficiently abrasion-resistant, go well with water wet and disintegrate spontaneously, contain 3-7 wt .-% silicon dioxide, based on the dry substance. Such product f. are obtained if, for example, 97-93 parts by weight of powdered charcoal, 10-24 parts by weight 30% silica sol and about 100-140 parts by weight of water - based on 100 parts by weight of end product - are used. The only task of the water is to make the mass capable of being granulated. Instead of dried Powdered charcoal can also be used in accordance with wet goods.

The activated carbon granules are i; oh granulation at temperatures between about 100 ° C to 250 ⁰ C, preferably between about 11O ⁰ C to 180 ⁰ C. dried. The temperature has no influence on the strength of the granules. It only affects the drying time. Although it is entirely possible, with careful drying, to produce anhydrous granules with good application properties, it is particularly advantageous to use activated charcoal granules with a residual moisture content of approx. 5-10%.

These granules disintegrate particularly quickly on contact with the liquid to be treated. It can higher residual moisture contents can also be set, but this turns out to be unnecessary weight ballast without any technical advantage.

Surprisingly, the activated carbons granulated with silica sols do not show any reduced adsorption capacity compared to the powdered starting activated carbons, although it should have been expected that the The micropore system of the activated carbon is stuck together by the silica gel that forms and is therefore partially ineffective will.

It has also been found that the treatment of technical solutions of various sugars and their derivatives can be made much more effective with the activated carbon granules of the invention. For example protein is removed from converted glucose thin juice much more completely than with other commercially available ones Activated carbons.

The mixing of the activated carbon with water and silica sol can be done in the usual mixing and kneading units take place, where only a sufficient homogenization has to be ensured. Through the mixed and Kneading process and the compaction caused by granulation in the apparatus used for this purpose of the coal mass have no effect on the ability of the granules to spontaneously decay.

It was found that by adding 0.1-5% gelatin in the form of an aqueous solution to the activated carbon mass an increase in the strength of the granules can be achieved prior to granulation. To be under gelatin Understood substances as they are z. B. in "Liquid Fruit, 9/1972, pp 388-406" are described. These gelatins are understood according to the invention under auxiliaries.

The present invention will now be explained in more detail using the following examples:

example 1

900 g of powdered activated carbon with a residual moisture content of 0.3% were mixed homogeneously with 1350 g of water and 133 g of 30% silica sol in a kneader in 30 minutes. The water and silica sol were first premixed before they were added to the activated carbon. The mass was then shaped in a screw press to give cylindrical shapes with a diameter of 4 mm and a length of 5-10 mm. The moldings were then dried at 120 ⁰ C to a residual moisture content of 7%. The finished granules contain - based on the granule dry substance - 4.7% SiOj from silica sol.

Example 2

900 g of powdered activated charcoal with a residual moisture content of 9.3% were mixed homogeneously with 1110 g of water, 133 g of 30% silica sol and 1.67 g of gelatin in a kneader in 30 minutes. The silica sol was first diluted with 555 g of water and the gelatin was dissolved in the remaining 555 g of water. Both solutions were then added successively to the activated carbon. It was then shaped as described in Example 1 and dried at 120 ° C. to a residual moisture content of 7%. The finished granules contain - based on the granule dry substance - 4.65% SiO ₂ from silica sol and 0.2% gelatin.

Example 3

By dissolving molasses in water and buffering with sodium phosphate buffer to a pH value of 7.0 A test mass solution was produced which, after filtration, had a color intensity corresponding to 13.5 ° Stammer exhibited. 1 liter of the test molasses solution was used at 80 ° for 30 minutes with various weights of the Starting powder carbon and the activated carbon, as indicated in the table, treated. Then the Solutions filtered through Selecta folded filter 602 1/2 h. A daylight colorimeter was used on the filtrates the remaining colors are determined.

The discoloration achieved in% was graphed as the ordinate against the amount of carbon required for this plotted in grams / liter as the abscissa. From the discoloration curves thus obtained, one could know those Remove the quantities of activated charcoal or granules that are required to increase 1 liter of PrC Vaelasse solution 5ö% of remaining color to decolorize.

Table 1
_, _ Determination of the decolorization performance compared to molasses solution

Serial No. Treatment method Achieved residual color Necessary for this

Amount of coal

% Grainm / liter

with the activated carbon granulate from example! 1 amount of coal

50 1.98 50 1.98 50 1.98

1 with occasional slight stirring

2 with constant strong shaking

,. 3 in the ground state (20% 71 μm) under

occasional gentle stirring

4 with the powdered activated carbon = starting 50 2.00

powder charcoal in example 1

The activated charcoal granulate from Example 1 showed the same good decolorization performance with a pu ufmelasse solution like the powdered starting activated carbon.

Example 4

With the powdered starting activated carbon and with the activated carbon granulate from Example 1 were on one German red wine tests to determine the discoloration capacity are carried out using the following method:

100 ml of red wine each was stirred with approx. 50 mg, 100 mg and 180 mg, based on dry matter, of the two types of charcoal in a beaker for 1 hour. Subsequently, the filter was filtered through a Selecta folded filter 602 for 1/2 h and the absorbance A of a 1 cm cuvette was measured from the filtered wine at 520 using a Zeisü spectrophotometer PM 2 DL. The extinction E ₀ was obtained from a corresponding blind test without charcoal.

Resl color and discoloration capacity were calculated according to the following equations:

Remaining color in percent -

Decolorization capacity =

E ₀ -E

Coal dry matter in grams

By entering the capacity as the ordinate and the associated residual color as the abscissa in a bilogarithmic In the coordinate system, the Freundlich isotherms were obtained. According to the principle of equal performance one now at z. B. 70% discoloration a parallel to the ordinate by the isotherms and received at the cut the equivalent decolorization capacities of each charcoal score at 70% decolorization.

Measured values and evaluation for both types of coal are compiled in Table 2.

Table 2

Determination of the decolorization capacity on red wine

Type of coal Dry Absorbance EnlHirbungs- Residual color Discoloration substance E or E ₀ capacity capacity per g E ₀ -E / g at 70% Discoloration

Starting powder charcoal

Activated carbon granulate
example 1

50
100
180

50
101
181

0.342 0.239 0.152

0.337 0.236 0.146

55.2
38.6
24.6

54.4
38.1
23.6

3.1
3.1

10

Original wine

0.619

The activated carbon granulate from Example 1 had the same decolorizing capacity with a given decolorization of 70% like the powdered starting activated carbon.

Example 5

The activated carbon granules from Example 1 and two commercially available activated carbons A and B were made according to the following Method tested for its ability to separate protein from converted thin glucose juice.

1 liter of converted thin glucose juice with a protein content corresponding to 0.5% by weight of peptone / 100 ° BX was mixed with different weights of activated charcoal or granulate in the stirring process Conditions treated. The residual protein content of the treated and filtered solutions was determined by a Protein test found. For this purpose, the protein formed by the action of nitric acid on the dissolved protein was used bright yellow color at pH 7.0 and 405 ^ m evaluated colorimetrically. The table indicates what amount of coal must be used to remove 70% of the dissolved protein.

Table 3

Protein removal from converted thin glucose juice

Coal sample

for 70% protein separation
required amount of coal
in grams of merchandise / liter

A 10.0

B 13.3

Activated carbon granulate from 8.5 Example 1

The activated charcoal granules from Example 1 showed protein separation from converted thin glucose juice a better performance than commercially available, comparatively used activated carbons.

} 0

35

40

45

50

55

60

Claims (4)

Patent claims: 1. Use of activated carbon granules, containing powdered activated carbon, silica sol and optionally Water and auxiliaries, the SiCV content of the activated carbon granules from 1 to 20% by weight, based on the Dry matter, for cleaning liquids. 2. Use of activated carbon granules according to claim 1, characterized in that the liquids alcoholic beverages and fruit juices are. 3. Use of the activated carbon granules according to claim 1, characterized in that the liquids Thin glucose juices are. 4. Use of the activated carbon granules according to one or more of claims 1 to 3, characterized characterized in that the excipient is gelatin.