DE2020294C3 - Process for the production of a high silica material for the adsorption of protein substances from the liquid phase - Google Patents

Description

The invention relates to a method of manufacture a highly silica-rich adsorbent, which especially used for removing proteins from wholly or predominantly aqueous phase can be.

The removal of certain proteins such. B. from juices, wines or beers is desirable and often necessary since these can lead to cloudiness during storage. Especially in the brewery industry Therefore, the most diverse substances have been tested for a long time, with which the disruptive ones Proteins could be removed by various technical processes. For the large-scale However, only bentonites proved to be used after appropriate digestion as well precisely defined silica gels can be used with success.

The silica gels are subject to special requirements, specifically with regard to the specific surface area, the pore volume and the mean pore diameter. It is known, however, that not every silica gel which falls within this range also shows uniform specific adsorption. The silica gel performance could be improved by post-treating the wide to medium-pored silica gel (Xerogcl with an average content of structural water hydration water of 2 to 4 percent by weight) with a preferably volatile strong acid with subsequent washing out of the acid and renewed drying of the treated silica gel reach. Mixtures of these silica gels with bentonite are also often used.

The purpose of the invention described below is to produce a specifically acting product which is suitable for protein adsorption and which does not have the swelling properties of bentonite.

The invention is based on the fact that a silicic acid hydrogel with an SiO ₂ -GeImU of 5.5 to 34, preferably 22 to 27 percent by weight with water in a pH range between 0.5 and 8.5 is freed from its soluble impurities and then this product with a water-containing silicate with divalent or trivalent cations, the ratio of SiO ₁ to metal oxide falls in the range between 0.5 and 4.5, preferably in the presence of boric acid or borates, mixed for at least 5 minutes under the influence of Is exposed to shear forces and then dried in a known manner. The finished product can optionally be washed with water.

Except the good specific adsorption, the softness of the material according to the invention represents a further technical advance over the brittle silica gel which can be difficult to marry in conventional mills to a seb ^r small Kömungsbereich

It was also observed in the manufacture of the products according to the invention that the characteristic data generally customary for silica gel (surface area, pore volume, mean pore diameter) are omitted and the water vapor isotherm at 20 ² C is recorded instead.

With this method, instead of an average pore diameter, you get a general overview the proportion of the individual pores from micro to / u the macropores. A good performing product made in accordance with the invention should be in the range \ on 80% rel. Absorb moisture about as much water as in the entire range between 0 and 80% rel. F. The greater this difference in favor of the 80/100% rel. F. fails, the more for protein adsorption suitable pores are present.

Examples

1. 201 silica hydrogel with 26.5% SiO ₂ and a pH of 3.6 are kneaded with 5 l of aluminum metasilicate in the form of filter cake with 16% plastic content with the addition of 50 g of boric acid in a Z kneader. Kneading was continued for 45 minutes. The finished product was dried at 145 ° C. with air circulation. The end product was extremely porous and soft and extremely easy to grind to a μ range.

2. In the Z kneader, 30 _{l of silica hydrogel with an SiO 2} content of 24 percent by weight and a pH of 4.2 mil I kg of magnesium silicate hydrate (3 MgO-10 SiO ₂ , 16% solids) were added with the addition intensively kneaded by 7.5 g of boric acid for 1 hour. This extrudable material was treated further as in Experiment 1 and showed the same properties in terms of processing. The pH in aqueous suspension (5%) was 7.8.

3. 201 silicic acid hydrogel with an SiO ₂ content of 25 percent by weight and a pH of 3.2 were added 70 g of sodium tetraborate 10 hydrate with 0.5 kg of aluminum metasilicate (according to Example 1) and 0.5 kg of magnesium silicate (according to Example 2) intimately kneaded in a Z kneader for 1 hour. The drying took place as in the previous examples. This product also immediately enabled the fastest possible grinding to the μ range.

In the following table are the isotherms of Products I to 3 are shown. The isotherm of the silica gel can be found under 4, which is in the Examples 1 to 3 used as a silica hydrogel as a reaction component and among the same Conditions such as the samples I to 3 according to the invention were dried to give the xerogel

% Weight percent, »ds. I. sample 4.6 36.0 r = au c Relutive 2.6 Il I III 8.0 Humidity 6.0 8.2 9.2 IV 20th 9.0 12.6 38.2 19.8 14.1 40 22.4 18.2 56.4 23.2 60 56.6 29.3 80 31.5 100 32.0

also tested for its stabilizing effect on beer. For sample I z. B. the following Data:

Ammonium sulfate (ml 20 ml)
Total nitrogen (mg N / 100 ml)
Coagulable nitrogen
(mg N / 100 ml)

, ₅ Esbachtriibung (%)

Anthocyanogens (mg / 1)

These data show that a new adsorbent is obtained by the process described can, which has a good adsorption performance for proteins, although each component, for dried itself, showing practically no activity in the protein adsorption. Same thing also shows a mixture according to ι! η examples without the influence no activity from shear forces.

Since most of the comparative figures on protein-active adsorbents are available in the brewery sector, the material described above was 2.0 among other things
77.08

1.66
66
29.2

sample
Il

4.9
72.80

1.33
42
28.4

Sample I was different in its effect

Beer tested. The ammonium sulfate limit was at

ίο 100 ml of beer increased from 10.5 to 17.0 ml, the value

for Esbach turbidity decreased at 10 ml reagent / 100 ml

Beer from 88 to 79. the color remained unchanged. At . Comparison with two commercially available products From pure silica, the forcing test (50 C 0 "C) remained with that produced according to the invention The product treated beer was clear, while both commercial products were slightly opal after 3.5 days showed. After 4.5 days, the beer treated with the commercial products was very opal, the with the

Product according to the invention treated beer opal.

Claims (3)

Patent claims:
I. Method of making egg lg initchnsj acidic adsorbent, especially suitable for protein adsorption from the liquid phase, characterized in that a silica hydrogel with an SiO ₂ content of 5.5 to 34, preferably 22 to 27 percent by weight with water in a pH range between 0, 5 and 8.5, preferably 2.9 and 4.4, is freed from its soluble impurities and then this product with a water-containing silicate with divalent or trivalent cations, the ratio of SiO ₂ to metal oxide in the range between 0 see , 5 and 4.5 precipitates, preferably in the presence of boric acid or borates, mixed, exposed to the influence of shear forces for at least 5 minutes and then dried in a known manner. 2. The method according to claim 1, characterized in that that the content of metal oxide between 0.1 and 65 percent by weight, preferably 3.3 and 7.8 percent by weight. 3. The method according to claim 1 and 2, characterized in that the product then Washed out with pure water until practically Ianen-free and, if necessary, then is dried at temperatures below 300 ° C.