RU2273516C2 - Biosorbent preparation method - Google Patents

Abstract

FIELD: biotechnology.

SUBSTANCE: preparation of biosorbents, in particular enterosorbents and hemosorbents, comprises preparing solution in 5-15% sodium hydroxide and introducing the solution into watered microcrystalline cellulose. Addition of gas former is accomplished by introducing it into wet mixture of β-casein and microcrystalline cellulose in amount 1-3% of the weight of cellulose. Biofilter is stabilized with acetone or ethyl alcohol acidified to pH 4.6 and then dried.

EFFECT: increased capacity of product.

6 cl, 1 dwg, 6 tbl, 6 ex

Description

The invention relates to industrial biotechnology and is intended to produce biosorbents, in particular enterosorbents and hemosorbents.

A known method of producing enterosorbents (patent RU 99102628 C1), providing for the fermentation of native and / or cellulose isolated from plant tissues to obtain microcrystalline cellulose and treatment with organic solvents to modify particle size and sorption capacity. The disadvantages of the method include the use of organic components that are prohibited for oral use, the use of microcrystalline cellulose, which has increased hygroscopicity, which reduces the sorption capacity of the drug.

The next method (patent RU 97113043 C1) for producing composite sorbents based on cellulose carriers is to pretreat the cellulose with a solvent system, followed by transferring the carrier into sparingly soluble hexacyanoferrates. The disadvantages are the technical complexity of the method, the use of expensive components.

The closest to the proposed technical essence and the achieved positive effect is a method for the production of modified cellulosic materials (patent RU 2256675, 2001.07.24), in which the cellulosic material is impregnated at room temperature with an aqueous solution of 0.25-2.0 wt.% AgNO ₃ at the ratio of cellulosic material: AgNO ₃ solution _of 1 g per 15-30 ml. The reaction mixture is heated at 85-150 ° C for 1-4 hours. To increase the silver content in an aqueous 0.25-2.0 wt.% AgNO ₃ solution, ammonia, glycerin, or a mixture of ammonia and glycerol are additionally introduced at an ammonia concentration of 0.5-15 vol.%, Glycerol concentration of 20-50 wt.% , the ratio of cellulosic material: aqueous solution is 1 g per 15-30 ml, and the reaction mixture is heated at 85-150 ° C for 1-4 hours. As the cellulosic material, microcrystalline cellulose, cotton fiber, fabric and articles thereof, linen fiber, linen and articles thereof, cotton dressings are used. The disadvantage is that the resulting system is used for the manufacture of dressings and cannot be used to create entero-and hemosorbents.

The purpose of the invention is to increase the sorption capacity of biosorbents.

To do this, in the proposed method for producing a biosorbent, which provides for the immobilization of protein on cellulose, followed by surface modification and stabilization of the biosorbent, β-casein is used as protein, which is applied to flooded microcrystalline cellulose at a temperature of 30 ÷ 50 ° C in a ratio of 1: 5 ÷ 7 in the form of 5 ÷ 15% sodium hydroxide solution.

Before immobilization, the cellulose is moistened with water in a ratio of 1: 1 ÷ 5. As a blowing agent, ammonium and carbonic salts are used in an amount of 1 ÷ 3% by weight of microcrystalline cellulose. The process is carried out with stirring for 5 ÷ 10 min and a temperature of 20 ÷ 25 ° C, followed by drying under vacuum.

Stabilization is carried out with acetone or ethyl alcohol, acidified with hydrochloric acid to a pH of 4.6 for 2 ÷ 5 minutes, followed by drying in air.

A method of obtaining a biosorbent is as follows.

To obtain β-casein in skim milk as a high molecular weight precipitant (flocculant) make 1 ÷ 2% solution of methylcellulose in water. Preliminary methylcellulose is introduced into warm water with a temperature of 50 ÷ 60 ° C until a 1 ÷ 2% solution is obtained. The mixture is kept for 1 hour. The temperature regime is due to the following restrictions. At temperatures below 50 ° C and above 60 ° C, the coagulation process takes longer.

The obtained colloidal gel of methylcellulose is introduced into skim milk in a ratio of 1 ÷ 2 by weight and thermostated at 10 ÷ 15 ° C for 8 ÷ 10 hours. When introducing a solution of methyl cellulose in a smaller amount, casein does not completely precipitate, while increasing the mass fraction of the solution of methyl cellulose, the yield of casein remains unchanged, and the component consumption increases. The separation of protein and polysaccharide at a temperature below 10 ° C is partially. Above 15 ° C, separation does not occur.

This method of concentrating casein is based on two physicochemical phenomena: the limited thermodynamic compatibility of proteins and polysaccharides in water, as well as the higher osmotic pressure of the polysaccharide solution compared to the osmotic pressure of the protein solution. Mixing solutions of protein and polysaccharide in certain concentrations leads to the formation of a two-phase system: the lower phase is a casein concentrate, and the upper is a polysaccharide phase. Through the interface, water is transferred from the protein solution to the polysaccharide solution until phase equilibrium is established, which causes the concentration of casein.

The bottom layer containing casein is separated on a separatory funnel.

The isolated β-casein is dissolved in a 5–15% sodium hydroxide solution in a ratio of 1: 5–7. According to the physicochemical properties, β-casein is an acidic protein. Therefore, it will dissolve in alkalis with a small concentration without denaturation. At a sodium hydroxide concentration below 5%, β-casein is poorly soluble, above 15% - irreversible protein denaturation may occur. 1 part of β-casein is dissolved in no more than 7 parts of sodium hydroxide solution, because an increased volume of liquid increases the drying process.

Cellulose is moistened with water at a ratio of 1: 1 ÷ 5. The increased fluid volume also increases the drying process. Dissolution and wetting of the components is necessary to improve mixing.

As a blowing agent, ammonium and carbonic salts are used in an amount of 1 ÷ 3% by weight of microcrystalline cellulose. Ammonium bicarbonate at a temperature easily decomposes into carbon dioxide and water, spontaneously removed from the mixture and not contaminating the final product with contaminants. The mass fraction of the blowing agent below 1% is insufficient to modify the surface of the biofilter. An increase in the mass fraction of more than 3% does not affect the sorption properties of the biofilter, but increases the cost and drying time.

The drawing shows a diagram of the industrial production of biosorbents.

A solution of β-casein and wetted microcrystalline cellulose are introduced (scheme) into a chemical reactor (1), where the product is continuously mixed. After 30 minutes, a blowing agent is introduced into the same reactor.

Stirring is continued for 15 minutes. Using a volumetric pump (2), the wet mixture is transferred to a spray dryer (3). The heater (6) maintains a temperature of no higher than 50 ° C. During spray drying, ammonium bicarbonate decomposes into components that increase the sorption surface of the biofilter.

Dry powder using a cyclone (7) and an elevator (9) is placed in a second chemical reactor (10), treated for 2 ÷ 5 minutes with acetone or ethyl alcohol, acidified with hydrochloric acid to pH 4.6 in the ratio of biosorbent: stabilizer 10: 1 ÷ 2. The use of acetone, ethyl alcohol and hydrochloric acid is due to their permitted use in the food industry. Acetone and alcohol are completely easily removed from the system upon further drying. Hydrochloric acid neutralizes sodium hydroxide, the sodium chloride salt formed in this process is also used in the food industry and at the same time is a preservative. The selected pH of 4.6 is due to the isoelectric deposition point of β-casein. The mass fraction of the introduced stabilizer in excess of 2% does not increase the durability of the product, but pollutes it with excess salt. When processing below 1% does not completely precipitate β-casein and neutralize the alkali.

The final drying of the modified and stabilized product is carried out in a vibration dryer (11).

The finished product is a powder, odorless, white with a cream tint, with a specific taste. Studies of the sorption capacity of the biosorbent without modification with an inorganic blowing agent and with modification were carried out on the results of the analysis of the adsorbed amount of iodide ion. The results are presented in tables 1, 2, 3.

Table 1
The sorption capacity of the biofilter with a mass fraction of β-casein 1% The content of iodide ions, mol / l Sorption capacity S, mmol / g Before adsorption, _ref , mol / L After adsorption C is _equal , mol / L unmodified modified unmodified, S _nemode modified, S _mod 0,0100 0.0084 0.0040 0.0080 0,0300 0,0200 0.0154 0.0070 0,0230 0.0650 0,0500 0,0483 0.0260 0.0450 0,1200 0.1000 0.0812 0,0460 0.0940 0.2700 0.2000 0.1545 0.0880 0.2280 0.5600 table 2
Sorption capacity of the biofilter with a mass fraction of β-casein 5% The content of iodide ions, mol / l Sorption capacity S, mmol / g Before adsorption, _ref , mol / L After adsorption C is _equal , mol / L unmodified modified unmodified, S _nemode modified, S _mod 0,0100 0.0890 0.0050 0.0055 0.0250 0,0200 0.0160 0.0110 0,0200 0.0450 0,0500 0.0425 0,0306 0,0375 0.0970 0.1000 0.0862 0,0630 0.0690 0.1870 0.2000 0.1690 0,1220 0.1570 0.3900 Table 3
Sorption capacity of the biofilter with a mass fraction of β-casein 10% The content of iodide ions, mol / l Sorption capacity S, mmol / g Before adsorption, _ref , mol / L After adsorption C is _equal , mol / L unmodified modified unmodified, S _nemode modified, S _mod 0,0100 0.0094 0.0060 0.0030 0,0200 0,0200 0.0165 0.0140 0.0175 0,0300 0,0500 0.0440 0,0350 0,0300 0,0750 0.1000 0.0910 0,0790 0.0450 0.1050 0.2000 0.1830 0.1550 0.0850 0.2250

Based on the data obtained, the change in sorption capacity ΔS of each biofilter and the average value of this change are calculated according to formulas (1) and (2), the results are presented in tables 4, 5, 6.

where S _mod is the sorption capacity of the modified biofilter, mmol / g;

S _nemode is the sorption capacity of the unmodified biofilter, mmol / g;

where ΔS _n is the change in the sorption capacity of each definition;

n is the number of definitions.

Table 4
Indicators of changes in the sorption capacity of the biofilter with a mass fraction of β-casein 1% S _nemode , mmol / g S _mod , mmol / g ΔS ΔS _total 0.0080 0,0300 3.75 2.92 0,0230 0.0650 2.83 0.0450 0,1200 2.67 0.0940 0.2700 2.87 0.2280 0.5600 2.46 Table 5
Indicators of changes in the sorption capacity of the biofilter with a mass fraction of β-casein 5% S _nemode , mmol / g S _mod , mmol / g ΔS ΔS _total 0.0055 0.0250 4,55 2.91 0,0200 0.0450 2.25 0,0375 0.0970 2,57 0.0690 0.1870 2.71 0.1570 0.3900 2.48 Table 6
Indicators of changes in the sorption capacity of the biofilter with a mass fraction of β-casein 10% S _nemode , mmol / g S _mod , mmol / g ΔS ΔS _total 0.0030 0,0200 6.67 3.17 0.0175 0,0300 1.71 0,0300 0,0750 2,50 0.0450 0.1050 2,34 0.0850 0.2250 2.65

Based on the data in tables 4, 5, 6, the sorption capacity of biofilters after modification increases on average by 3 times.

In unregulated conditions of prolonged storage, the composition and characteristics of biosorbents do not change for 1 year.

The proposed method is illustrated by specific examples of its use.

Example 1. 1 kg of β-casein is dissolved in 5 l of a 5-15% NaOH solution. The resulting solution was suspended with constant stirring with 100 kg of microcrystalline cellulose. Then make 2 kg of ammonium bicarbonate. The resulting mixture is spray dried at a temperature of 30 ÷ 50 ° C.

The prepared biosorbent is treated in an enameled chemical reactor with 10 l of acetone, acidified with hydrochloric acid to a pH of 4.6 units. Re-drying takes place on a vibratory dryer. Thus obtained biofilter contains by weight 1% β-casein.

Example 2. 1 kg of β-casein is dissolved in 5 l of a 5-15% NaOH solution. The resulting solution was suspended with constant stirring with 100 kg of microcrystalline cellulose. Then make 2 kg of ammonium bicarbonate. The resulting mixture is spray dried at a temperature of 30 ÷ 50 ° C.

The prepared biosorbent is treated in an enameled chemical reactor with 10 l of ethanol, acidified with hydrochloric acid to a pH of 4.6 units. Re-drying takes place on a vibratory dryer. Thus obtained biofilter contains by weight 1% β-casein.

Example 3. 5 kg of β-casein is dissolved in 5 l of a 5-15% NaOH solution. The resulting solution was suspended with constant stirring with 100 kg of microcrystalline cellulose. Then make 2 kg of ammonium bicarbonate. The resulting mixture is spray dried at a temperature of 30 ÷ 50 ° C.

The prepared biosorbent is treated in an enameled chemical reactor with 10 l of acetone, acidified with hydrochloric acid to a pH of 4.6 units. Re-drying takes place on a vibratory dryer. Thus obtained biofilter contains by weight 5% β-casein.

Example 4. 5 kg of β-casein is dissolved in 5 l of a 5-15% NaOH solution. The resulting solution was suspended with constant stirring with 100 kg of microcrystalline cellulose. Then make 2 kg of ammonium bicarbonate. The resulting mixture is spray dried at a temperature of 30 ÷ 50 ° C.

The prepared biosorbent is treated in an enameled chemical reactor with 10 l of ethanol, acidified with hydrochloric acid to a pH of 4.6 units. Re-drying takes place on a vibratory dryer. Thus obtained biofilter contains by weight 5% β-casein.

Example 5. 10 kg of β-casein is dissolved in 5 l of a 5-15% NaOH solution. The resulting solution was suspended with constant stirring with 100 kg of microcrystalline cellulose. Then make 2 kg of ammonium bicarbonate. The resulting mixture is spray dried at a temperature of 30 ÷ 50 ° C.

The prepared biosorbent is treated in an enameled chemical reactor with 10 l of acetone, acidified with hydrochloric acid to a pH of 4.6 units. Re-drying takes place on a vibratory dryer. Thus obtained biofilter contains by weight of 10% β-casein.

Example 6. 10 kg of β-casein is dissolved in 5 l of a 5-15% NaOH solution. The resulting solution was suspended with constant stirring with 100 kg of microcrystalline cellulose. Then make 2 kg of ammonium bicarbonate. The resulting mixture is spray dried at a temperature of 30 ÷ 50 ° C.

The prepared biosorbent is treated in an enameled chemical reactor with 10 l of ethanol, acidified with hydrochloric acid to a pH of 4.6 units. Re-drying takes place on a vibratory dryer. Thus obtained biofilter contains by weight of 10% β-casein.

Claims (6)

1. A method of obtaining a biosorbent, including the immobilization of protein on a cellulose carrier, characterized in that β-casein is used as a protein, microcrystalline cellulose is used as a carrier, modification is carried out at 30 ÷ 50 ° C in an alkaline medium, followed by foaming of the suspension by injection into blowing agent, drying, stabilization by treatment with an acidified solution of acetone or ethyl alcohol and re-drying in air. 2. The method according to claim 1, in which microcrystalline cellulose is used as an organic carrier, onto which β-casein is immobilized at a temperature of 30 ÷ 50 ° C, followed by modification with inorganic blowing agents and stabilization. 3. The method according to claim 1, characterized in that β-casein is isolated from skim milk by flocculation using as a flocculant a solution of methyl cellulose 1 ÷ 2% by weight, with a ratio of skim milk: a solution of methyl cellulose 2 ÷ 1, at a temperature of 10 ÷ 12 ° C. 4. The method according to claim 1, characterized in that the immobilization is carried out by mixing the components, previously β-casein is dissolved in a 5 ÷ 15% sodium hydroxide solution in a ratio of 1: 5 ÷ 7, and the cellulose is moistened with water at a ratio of 1: 1 ÷ 5. 5. The method according to claim 1, characterized in that as a blowing agent, ammonium and carbonic salts are used in an amount of 1 ÷ 3% by weight of microcrystalline cellulose. 6. The method according to claim 1, characterized in that the acetone or ethyl alcohol used as stabilizers is acidified with hydrochloric acid to a pH of 4.6.