RU2531829C1 - Filtration material, method of its production and application - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: set of inventions relates to production of filter material with high adsorption properties, particularly, to fibrous filter medium and to methods of its production and application, and can be used for deactivation of viruses at water filtration via bed or beds of this material. Fibrous ion-exchange filter material is produced by alkaline hydrolysis by polyacryl nitrile in the presence of amine-bearing compounds and has isoelectric surface point outside the range pH 6-9 and full exchange capacity of at least 4 mmol/g. Proposed method comprises production of material by modification of polyacryl nitrile or its copolymers in alkaline medium in the presence of modifier containing aliphatic hydrocarbon fragments in their molecular structure and at least two amino groups as well as modifier in reaction mix with respect to initial material in amount of at least 100 mol/kg.

EFFECT: efficient deactivation of viruses at filtration of aqueous media, ion-exchange material with isoelectric surface point outside pH range of 6-9.

11 cl, 4 dwg, 3 tbl, 8 ex

Description

Technical field

The group of inventions relates to the production of filtering material with high adsorbing properties, namely, fibrous filtering material and methods for its preparation and use, and can be used to deactivate viruses by filtering water through a layer or layers of this material.

Despite modern means of purifying water from harmful impurities and pathogenic microorganisms, viruses are transmitted through water supply systems and jeopardize the general population. In everyday life, filters containing filtering materials are most popular. The prior art offers a variety of filter materials with the ability to adsorb various particles, including viruses, from water.

State of the art

In the present invention, the term virus (lat. Virus - poison) means a subcellular infectious agent that can only be reproduced inside living cells of the body. By nature, viruses are autonomous genetic elements that have an extracellular stage in the development cycle. Viruses are microscopic particles consisting of nucleic acid molecules - DNA or RNA, enclosed in a protein coat. Viruses are able to infect living organisms and are obligate parasites, as they are not able to multiply outside the cell. Outside the cell, viral particles do not show signs of life and behave like particles of organic polymers.

Many viruses that can cause serious diseases can enter the human body with drinking water. In the field of water purification technologies, the removal or decontamination of viruses is given special attention related to both the importance of solving this problem and the technical complexity of this solution.

Most often, adsorption methods are used to remove viruses from water, which involve the use of finely dispersed materials with a high surface charge and a developed contact area with water. Fixation of the virus occurs mainly due to electrostatic interactions. In addition to viruses, water contains a significant amount of substances of organic origin with the same surface charge: natural polymers (humic acids), technogenic substances (surfactants), microorganisms and their metabolic products.

Therefore, the fixation of viruses proceeds in the form of competitive adsorption with substances of a similar nature, the mass content of which is much greater than viruses.

Known filter material with the ability to adsorb from water various particles, including viruses [WO 2007018454, RU 2005125140, 2007]. According to the invention, submicron particles of alumina hydrate are mechanically applied to the surface of the polymer fibers, which in contact with water acquire a positive charge, due to which the filter material acquires the indicated ability. A disadvantage of the known material is the lack of chemical bonding of the active particles with polymer fibers. As a result of this, particles can be removed from the filter layer. In addition, particles of hydrated alumina are capable of dissolving at a pH of water above 8, which in real-life conditions will lead to a rapid loss of activity of the material.

A device for filtering is known, which, when passing water through it to inhibit bacteria and viruses, contains at least one fibrous structure, which is a mixture of nanofibers of aluminum hydroxide and other fibers, placed in a matrix to create asymmetric pores for filtering particles from small to nanoscale [patent US 7390343, 2008]. In a known solution to achieve the desired result, the active component, inactivating viruses, must be applied to an inert carrier. However, due to the physical properties of the inert carrier, it is not possible to apply the active component in the amount required to remove viruses in large quantities.

Known filter material, which includes particles of activated carbon coated with a cationic polymer [RU 2372983, 2009; WO 2006110632; US 7922008]. As a result, the surface of the material acquires the ability to adsorb various particles, including viruses. The disadvantage of this material is the ability to partially wash off the water-soluble polymer into water during the filtration process.

Known material, which is a filter medium, which includes particles of a sparingly soluble compound having an isoelectric point at a higher pH value than the filtered medium, while these particles are bound by a low-melting polymer binder [US 6989101, 2006].

It should be borne in mind that the virus in water is a particle with a predominantly protein surface with a low intrinsic charge, depending on the pH of the medium. Therefore, the binding force of the virus on the surface is small, and the virus is not fixed irreversibly at the point of contact with the surface of the adsorbent, but with a constant flow of liquid along the surface, the virus migrates, and with local fluctuations in the composition of water, its desorption is possible.

Known material obtained by alkaline hydrolysis of polyacrylonitrile in the presence of hydrazine as a crosslinking agent [US 5109028, 1992].

The closest analogue of the proposed material in technical essence is a fibrous ion-exchange filter material obtained by alkaline hydrolysis of polyacrylonitrile in the presence of amine-containing compounds [WO 2009057235 A1].

Known methods for the modification of polycarilonitrile fibers in an alkaline medium in the presence of hydrazine, which allow to obtain materials with a high total exchange capacity. The surface charge of these materials is determined by the ratio of acid and basic groups in the material and the degree of dissociation of these groups. Known methods for modifying polyacrylonitrile, it is possible to obtain materials with insufficient surface charge in the pH range of 6-9. Often these materials have an isoelectric point in the indicated pH range. For this reason, the indicated materials did not previously show antiviral properties.

A known method of producing modified polymers based on polyacrylonitrile using hydroxylamine and its derivatives on [RU 94027687 A, 1994]. As in the case of materials obtained using hydrazine, the main groups of low basicity are formed in the synthesis process.

Modifications of polyacrylonitrile are known by hydrazine treatment with simultaneous or subsequent alkaline hydrolysis. These methods are used to obtain materials for absorption: basic gases [US 5766757, 1998; US 5783304, 1998], moisture-absorbing materials [US 5853879, 1998], materials with increased affinity for dyes [WO 2009057235, 2009].

A known method of producing a material according to which alkaline hydrolysis of polyacrylonitrile in the presence of hydrazine leads to an increase in the nitrogen content in the material and to its acquisition of water-absorbing and antibacterial properties [US 5.292.822, 1994].

Also known is a method of producing ion-exchange polyacrylonitrile fiber by alkaline hydrolysis in the presence of hydrazine, characterized by the presence of an additional step of removing traces of hydrazine [RU 2262557, 2005].

All materials obtained using hydrazine as a modifier and a crosslinking agent have a common drawback. Hydrazidines formed during the interaction of nitrile groups with hydrazine, as well as the products of their partial hydrolysis - hydrazides, have a low basicity. Therefore, upon contact with water in the pH range of 6–9, typical for drinking water, these groups do not give charged protonated forms, as a result of which this class of materials does not have a pronounced antiviral activity.

The closest analogue of the proposed method is a method for producing a fibrous material by modifying polyacrylonitrile or its copolymers in an alkaline medium in the presence of a modifier containing aliphatic hydrocarbon fragments and at least two amino groups in its molecular structure [WO 2009057235 A1].

Among the known methods of water disinfection, chlorine compounds are still the most widely used, after the treatment of which water is standard for indicator bacteria, but can contain viruses.

A known method of water treatment that provides effective water purification from viral contamination using a heterogeneous sensitizer [RU 2470051, 2011].

A known method of filtering, including ensuring contact of the flowing water with the filter material, which is used as an organic synthetic polymer cloth, on the fibers of which particles of aluminum oxide hydrate are fixed [EA 012492, 2008, WO 200701845], adopted as the closest analogue.

Disclosure of invention

The basis of the group of inventions is the task of obtaining a material with a high degree of surface charge outside the pH range of 6-9, as well as a method for producing a material that provides a high content of charged fixed groups in the material, and a filtration method that provides sufficient contact time of the filtered fluid with the layer or layers of this material.

The technical result achieved using the group of inventions consists in the ability of a fibrous ion-exchange filter material having an isoelectric surface point outside the pH range of 6-9 to deactivate viruses when they filter aqueous media.

To solve the problem and achieve the technical result, a group of inventions is proposed, united by a common inventive concept.

One aspect of the invention is a fibrous ion exchange filter material obtained by alkaline hydrolysis of polyacrylonitrile in the presence of amine-containing compounds, characterized in that it has an isoelectric surface point outside the pH range of 6-9.

In an additional aspect, the material is characterized by a pH value of the isoelectric point of less than 6.

In an additional aspect, the material is characterized by a pH value of the isoelectric point of more than 9.

In an additional aspect, the material is characterized in that it has a total exchange capacity of at least 4 mmol / g.

Another aspect of the invention is a method for producing a fibrous ion-exchange filter material, comprising obtaining a material by modifying polyacrylonitrile or its copolymers in an alkaline medium in the presence of a modifier containing aliphatic hydrocarbon fragments and at least two amino groups in its molecular structure, characterized in that it contains a modifier in the reaction mixture according to relative to the starting material in an amount of not less than 100 mol / kg

In an additional aspect, the production method is characterized in that an aliphatic diamine is used as a modifier.

In an additional aspect, the production method is characterized in that ethylene diamine is used as a modifier.

In an additional aspect, the production method is characterized in that hexamethylenediamine is used as a modifier.

A further aspect of the invention is a filtering method comprising contacting the flowing water with a filter material, characterized in that a fibrous ion exchange filter material obtained according to the invention is used.

In an additional aspect, the filtering method is characterized in that the filter layer or layers are characterized by a specific contact surface of the fibrous material with flowing water of at least 300 cm ² / cm ³ .

In an additional aspect, the filtering method is characterized in that the packing density of the filter material in the layer or layers is in the range from 0.15 to 0.50 g / cm ³ .

In an additional aspect, the filtering method is characterized in that the effective contact time of the flowing water with the filter material is at least 5 seconds.

In an additional aspect, the filtering method is characterized in that the filtering is carried out through several layers of filtering materials, at least one of the layers consists of a material according to the invention.

In an additional aspect, the filtering method is characterized in that the filtering is carried out through several layers of filtering materials, at least two of which are composed of material according to the invention.

The materials obtained by the proposed method have a significant surface charge, which is found when measuring the zeta potential of the material during the flow of aqueous solutions of electrolytes through a compacted layer of material. In the pH range of 6–9 and the ionic strength of the solution 10–3 M, the characteristic values of the zeta potential are more than 20 mV in absolute value. The isoelectric points of the materials, determined by the dependence of the zeta potential on pH, lie outside the pH range for drinking water (6–9).

According to the invention, the materials obtained by alkaline hydrolysis of polyacrylonitrile fibers in the presence of dibasic amines, mainly ethylenediamine. In this case, the synthesis is carried out with a large excess of diamine, so that the molar content of diamine in the reaction bath relative to the weight of the starting polyacrylonitrile is more than 100 mol / kg, that is, five times the molar content of nitrile groups in the starting polymer, which is 18 for pure polyacrylonitrile 9 mol / kg. The alkali content (NaOH) in the reaction affects the rate of modification, but not the properties of the final material. Therefore, in the examples below, it was selected at the level of the prior art and amounted to 0.5-1 mol / l of solution.

Diamines are characterized by much greater basicity than traditionally used for the modification of polyacrylonitrile, hydrazine. So the first and second constants of hydrazine basicity are 1.2 × 10-6 and 8.9 × 10-16, ethylenediamine - 1.2 × 10-4 and 9.8 × 10-8, respectively. Under conditions of excess diamine, at least part of its molecules interact with the nitrile groups of the polymer of only one of the amino groups. The free amino group is protonated by interaction with carboxyl groups formed during the hydrolysis of nitrile groups. Thus, ionized acidic and basic groups are present in the material, and the surface charge of the fibers is determined by the ratio of these groups.

During hydrolysis in an aqueous medium, the material contains an excess of carboxyl groups with respect to the main groups; therefore, such materials are characterized by negative values of the zeta potential in the pH range of drinking water (6--9). Hydrolysis in a non-aqueous solvent (ethylene glycol or glycerin) leads to the production of a material with an excess of basic groups and, accordingly, to positive values of the zeta potential in contact with water.

To remove viruses from aqueous media, they are filtered through a layer or layers of material according to the invention. Being a fibrous material, chemically modified polyacrylonitrile forms elastic filter layers. Depending on the compression force of the layer, filter layers with a packing density of 0.15 to 0.50 g / cm ³ can be obtained. A lower density of the filtration material leads to inefficient filtration - due to channel effects in the material layer, a higher density - to a low permeability of the filter layer.

Since the binding of viral particles occurs on the surface of the fibers, an important characteristic of the filter layer is the specific contact surface of the material with water, referred to as the unit volume of the filter layer. The specific surface area of the modified polyacrylonitrile fibers with a thickness of 20 μm and an intrinsic density of 1.15 is 0.17 m ² / g. Then the above range of densities of laying the filter layer corresponds to the range of specific surfaces of the material in the filter layer 255-850 cm ² / cm ³ .

The second important parameter of the filter layer is the contact time of the liquid with the filter layer, defined as the ratio of the volume of the filter layer to the volumetric rate of liquid filtration. It should be borne in mind that layers with different compaction of the material have a different fraction of the free volume filled with water. Therefore, the correct characteristic of the filtration process is the effective contact time, calculated by the formula:

$$t_{\mathrm{uh}f}==\frac{V(\mathrm{one}-\frac{\rho \text{'}\text{'}}{\rho })}{q}$$

where V is the volume of the filter layer, p is the intrinsic density of the filter material, p 'is the packing density of the material in the filter layer, q is the volumetric flow rate of the liquid. It was experimentally established that the effective contact time necessary to remove viruses should be at least 5 seconds.

A brief description of the graphic materials

The invention is illustrated by examples: methods for producing examples of fibrous ion-exchange filter material (examples 1-7); material testing (example 8) and methods for deactivating viruses in aqueous media (examples 9 and 10).

The essence of the group of inventions is illustrated by graphic materials.

Figure 1 shows a glass flow column for measuring the potential for the flow of water through the filter layer.

Figure 2 presents a graph of the dependence of the zeta potential of the material obtained according to examples (1-3) on pH values, when using as an electrolyte 10 ^-3 M mixed buffer solutions of sodium acetate with acetic acid with different pH values.

Figure 3 presents a graph of the dependence of the zeta potential of the material obtained according to examples (4-6) on pH values; when used as an electrolyte solution, 10 ^-3 M mixed buffer solutions of sodium carbonate and sodium bicarbonate with different pH values were used.

Figure 4 presents a graph of the dependence of the zeta potential of the material obtained according to examples 7 on pH values; when used as an electrolyte solution, 10 ^-3 M mixed buffer solutions of sodium carbonate and sodium bicarbonate with different pH values were used

Table 1 presents the test results for the presence or absence of active viral particles in water, filtered material obtained according to examples (1-7). The human rotavirus HRV / SPb / 884/10/05 was used as the viral culture.

Table 2 presents the test results for the presence or absence of active viral particles in water filtered through two filter layers, one of which is a material according to the invention. In this case, norovirus was used as a viral culture (noro-Spb / 2005).

Table 3 presents the test results for the presence or absence of active viral particles in water filtered through three filter layers, two of which are material according to the invention. In this case, norovirus was used as a viral culture (noro-Spb / 2005).

The implementation of the invention

Example 1. A method of obtaining a fibrous ion-exchange filter material in an aqueous medium

A fibrous ion-exchange filter material was prepared according to the following procedure: 4 g of polyacrylonitrile fiber (manufactured by Tai'an Tongban Fiber Co., Ltd, China) was placed in a 250 ml conical flask, to which 200 ml of a modifying solution was added. The solution is prepared on a water basis, the concentration of ethylene diamine is 2.5 mol / l (150 g / l), the concentration of alkali - sodium hydroxide is 1 mol / l (40 g / l).

The flask with the reaction mixture is heated in a water bath with continuous stirring, the modification process is carried out until the fibers are dark red. After this, the fibers of the material are separated from the solution, washed with plenty of water. Then the material is alternately treated with 0.1 M solutions of sodium hydroxide and hydrochloric acid to remove residual amounts of reagents.

After final washing and drying, the material acquires a tan color. The resulting material contains functional groups of the main and acidic nature. Exchange capacity for each type of group is determined in accordance with GOST 20255.1-89 “Ionites. Method for the determination of statistical exchange capacity "or ASTMD 2187-94 (1998)" Standard Test Methods for PHysical and Chemical Properties of Particulate Ion-Exchange Resins ".

The exchange capacity for anion-exchange groups is 1.2 mmol / g, for cation-exchange groups is 3.3 mmol / g, the total exchange capacity is 4.5 mmol / g.

To determine the isoelectric point of the sample, the material is placed in a glass flow column (see Figure 1), equipped with silver chloride electrodes at the inlet and outlet (1), a layer of fibrous material (3) is located in the column on the perforated partition (2). To measure the electrical conductivity of the solution and the filter layer, there are, respectively, two pairs of platinum electrodes (4). During the flow of water through the column, the potential of the flow of the electrolyte solution is measured.

According to the measurement results of the flow rate and pressure drop of the liquid, the zeta potential of the material is calculated by the equation:

$$\zeta =\frac{\eta {\lambda }_s}{\epsilon {\epsilon }_0}\frac{\Delta \varphi }{\Delta {\rm P}}$$

where Δφ is the measured value of the flow potential; ΔP - pressure loss during fluid flow through a porous material; η is the dynamic viscosity of the liquid; λ _s - intrinsic electrical conductivity of the porous medium; ε and ε ₀ - dielectric constant of the medium and vacuum.

As an electrolyte, 10 ^-3 M mixed buffer solutions of sodium acetate with acetic acid with different pH values were used. The solution was passed through the column until a stable pH was established at the outlet of the column.

According to the results of a series of measurements, the dependence of the zeta potential of the material on pH was obtained, which is presented in Figure 2. As can be seen from the graph (see Figure 2), the pH value for the isoelectric point was 4.2.

Example 2

The preparation of the material is carried out according to a procedure analogous to example 1, and with the same composition of the modifying solution, but with a difference from example 1 in terms of the length of the processing time. The modification process is carried out before the acquisition of bright orange fibers. The washing process is carried out as in example 1. After the final washing and drying, the material acquires a yellow color. The exchange capacity for anion-exchange groups was 1.0 mmol / g, for cation-exchange groups - 2.5 mmol / g, the total exchange capacity was 3.5 mmol / g. As can be seen from the graph presented in Figure 2, the pH value of the isoelectric point, determined analogously to example 1, was 4.9.

Example 3

The preparation of the material is carried out according to a method similar to Example 1. In contrast to Example 1, the concentration of the modifying solution was 1.5 mol / L for ethylene diamine and 1 mol / L for sodium hydroxide. The modification process is carried out before the acquisition of fibers of dark red color. The washing process is carried out as in example 1. After the final washing and drying, the material acquired a brownish-yellow color. The exchange capacity for anion-exchange groups was 0.9 mmol / g, for cation-exchange groups was 3.3 mmol / g, and the total exchange capacity was 4.2 mmol / g. As can be seen from the graph presented in Figure 2, the pH value of the isoelectric point, determined analogously to example 1, was 6.4.

Example 4. A method of obtaining a fibrous ion-exchange filter material in a non-aqueous medium

A fibrous ion-exchange filter material was prepared according to the following procedure: 4 g of polyacrylonitrile fiber (manufactured by Tai'an Tongban Fiber Co., Ltd, China) was placed in a 250 ml conical flask, to which 200 ml of a modifying solution was added. The solution is prepared on the basis of ethylene glycol containing 5% water. The concentration of ethylenediamine was 2.5 mol / l (150 g / l), the concentration of alkali - sodium hydroxide was 0.5 mol / l (8 g / l). The modification process is carried out before the acquisition of fibers of dark red color. The washing process is carried out as in example 1. After the final washing and drying, the material becomes brown. The exchange capacity for anion-exchange groups was 2.9 mmol / g, for cation-exchange groups - 1.3 mmol / g, and the total exchange capacity was 4.2 mmol / g.

To determine the isoelectric point, the procedure described in Example 1 is used, but 10 ^-3 M mixed buffer solutions of sodium carbonate and sodium bicarbonate with different pH values were used as the electrolyte solution. The obtained dependence of the zeta potential of the material is presented in figure 3.

As can be seen from the graph (see Figure 3), the pH value of the isoelectric point was 9.8.

Example 5

The preparation of the material is carried out according to a procedure analogous to example 4 and with the same composition of the modifying solution, but with a difference from example 4 in terms of the length of the processing time. The modification process was carried out before the acquisition of orange fibers. The washing process was performed according to example 1. After the final washing and drying, the material becomes yellow-orange. The exchange capacity for anion-exchange groups was 1.5 mmol / g, for cation-exchange groups - 0.9 mmol / g, and the total exchange capacity was 2.4 mmol / g.

As can be seen from the graph presented in Figure 3, the pH value of the isoelectric point, determined analogously to example 4, was 9.2.

Example 6

The preparation of the material was carried out according to a method similar to Example 4. In contrast to Example 4, the concentration of the modifying solution was 1.5 mol / L for ethylenediamine and 0.5 mol / L for sodium hydroxide. The modification process was carried out before the acquisition of dark red fibers. The washing process was carried out as in example 1. After the final washing and drying, the material acquired a brownish-yellow color. The exchange capacity for anion-exchange groups was 2.2 mmol / g, for cation-exchange groups — 2.5 mmol / g, and the total exchange capacity was 4.5 mmol / g.

As can be seen from the graph presented in Figure 3, the pH value of the isoelectric point, determined analogously to example 1, was 7.8.

Example 7

The preparation of the material was carried out by a method analogous to example 4, but using hexamethylenediamine instead of ethylene diamine. The concentration of hexamethylene diamine in the modifying solution was 2.5 mol / L. The modification process was carried out before the acquisition of red-brown fibers. The washing process was performed according to example 1.

After the final washing and drying, the material acquired a red-brown color. The exchange capacity for anion-exchange groups was 3.5 mmol / g, for cation-exchange groups - 1.2 mmol / g, and the total exchange capacity was 4.7 mmol / g.

As can be seen from the graph presented in Figure 4, the pH value of the isoelectric point, determined analogously to example 4, was 9.5.

Example 8. Testing of materials for the ability to deactivate viruses during water filtration

Testing of materials obtained by the method described in examples 1-7, is as follows. Images of filter materials weighing 5 g are placed in filter columns and compacted to a density of 0.25 g / cm ^{3 of the} filter layer. Through the prepared columns, water with viral culture introduced is passed.

The filtration rate was in all cases 50 ml / min, so the effective contact time of the liquid with the filter layer calculated by the formula was 18.5 seconds. The volume of filtered water left in each case 1 liter. The filtrate was analyzed for the presence of active viral particles.

The human rotavirus HRV / SPb / 884/10/05 was used as the viral culture. Viral particles of this type have a size of about 70 nm. Viral culture suspensions of 10 ⁶ particles per ml were used.

Virus concentration was determined by PCR (polymerase chain reaction) using AmpliSens Rota-Group A virus reagents (manufactured by InterLabService), the detection limit of viruses by this method is 10 ² TCD / ml (TCD - tissue cytopathic doses).

The test results are presented in Table 1, where the signs (+) and (-), respectively, indicate the presence or absence of active viral particles in the filtered water.

Table 1 No. of examples illustrating the receipt of materials PH value of the isoelectric point The value of the total exchange capacity, mmol / g The presence or absence of viruses in the filtrate one 4.2 4,5 - 2 4.9 3,5 + 3 6.4 4.2 + four 9.8 4.2 - 5 9.2 2,4 + 6 7.8 4,5 + 7 9.5 4.7 -

Example 9. Testing of materials for the ability to deactivate viruses in various modes of water filtration

Investigated the filtration of an aqueous medium containing viruses through filter columns with a diameter of 1 cm ² . Each column contained two layers of filter media.

As the lower layer, a layer of the material obtained according to Example 1 was used with a packing density from the filter layer of 0.10 to 0.45 g / cm ^{3 of the} filter layer. The total volume of the filter layer remained unchanged at 5 ml.

The top layer of the column was filled with a mixture of coconut activated carbon NWC 18x40 (manufactured by Indo German Carbons, Ltd., India) and ion exchange resin D112 (manufactured by Bidragon Resins Co., Ltd, China). Materials were taken in equal volume fractions. The total volume of the layer of mixed granular materials was 5 ml.

Virus-added water was passed through the prepared columns. The filtration rate in various experiments ranged from 25 to 75 ml / min. The volume of filtered water left in each case 1 liter. Filtered water was analyzed for the presence of active viruses.

Norovirus was used as the viral culture (noro-Spb / 2005). Viral particles of this type have a size of about 30 nm. Viral culture suspensions of 10 ⁶ particles per ml were used. Virus concentration was determined by polymerase chain reaction using AmpliSens Caliciviruses: Noroviruses reagents (manufactured by InterLabService, Russia).

The test results are presented in Table 2, where the signs (+) and (-), respectively, indicate the presence or absence of active viruses in the filtered water.

table 2 Nn experiment The weight of the material in a layer of 5 ml,
g The density of the material in the filter layer, g / cm ³ The specific surface of the material in the filter layer, cm ² / cm ³ Filtration rate, ml / min Effective time of contact of water with material, sec The presence or absence of viruses in the filtrate one 0.75 0.15 255 25 10,4 + 2 0.75 0.15 255 fifty 5.2 + 3 1.25 0.25 425 25 9,4 - four 1.25 0.25 425 fifty 4.7 - 5 1.25 0.25 425 75 3,1 + 6 1.75 0.35 595 25 (*) 8.4 - 7 2.00 0.45 680 10(*) 18.3 - (*) - with a dense installation of the material, the filtration rate is limited by the working pressure of the pump.

Example 10. Testing of materials for the ability to deactivate viruses in various modes of water filtration

Investigated the filtration of an aqueous medium containing viruses through filter columns with a diameter of 1 cm ² . Each column contained three layers of filter media.

As the lower layer, a layer of the material obtained according to Example 1 was used with a packing density from the filter layer of 0.15 to 0.50 g / cm ^{3 of the} filter layer. The total volume of the filter layer remained unchanged at 2.5 ml.

The middle layer of the column was filled with a mixture of coconut activated carbon NWC 18x40 (manufactured by Indo German Carbons, Ltd., India) and ion exchange resin D112 (manufactured by Bidragon Resins Co., Ltd, China). Materials were taken in equal volume fractions. The total volume of the layer of mixed granular materials was 5 ml.

As the upper layer used a layer of material obtained according to Example 4, with a packing density of the filter layer from 0.15 to 0.50 g / cm ³ . The total volume of the filter layer remained unchanged at 2.5 ml.

Through the prepared columns passed water with the introduced viral culture similarly to Example 9.

The test results are presented in Table 3, where the signs (+) and (-) respectively indicate the presence or absence of active viral particles in the filtrate.

Table 3 Nn experiment Weight, material in a 2.5 ml layer,
g The density of the material in the filter layers,
g / cm ³ The specific surface of the material in the filter layers, cm ² / cm ³ Filtration rate, ml / min Effective time of contact of water with fibrous material, sec The presence or absence of viruses in the filtrate one 0.375 0.375 0.15 255 25 10,4 - 2 0.375 0.375 0.15 255 fifty 5.2 + 3 0.625 0.625 0.25 425 25 9,4 - four 0.625 0.625 0.25 425 fifty 4.7 - 5 0.875 0.875 0.35 595 40 5.1 - 6 1.00 1.00 0.45 680 25 7.1 - 7 1.25 1.25 0.50 756 fifteen(*) 10.9 - (*) - with a dense installation of the material, the filtration rate is limited by the working pressure of the pump.

The above examples convincingly confirm that the obtained material has high adsorbing and filtering properties and the ability to deactivate viruses when filtering flowing water, which allows it to be used to disinfect water by deactivating viruses.

Claims (11)

1. Fibrous ion-exchange filter material obtained by alkaline hydrolysis of polyacrylonitrile in the presence of amine-containing compounds, characterized in that it has an isoelectric surface point outside the pH range of 6-9. 2. The material according to claim 1, characterized in that it is characterized by a pH value of the isoelectric point of less than 6. 3. The material according to claim 1, characterized in that it is characterized by a pH value of the isoelectric point of more than 9. 4. The material according to claims 1-3, characterized in that it has a total exchange capacity of at least 4 mmol / g. 5. A method for producing a fibrous ion-exchange filter material according to claims 1 to 4, comprising obtaining a material by modifying polyacrylonitrile or its copolymers in an alkaline medium in the presence of a modifier containing aliphatic hydrocarbon fragments and at least two amino groups in its molecular structure, characterized in that it contains a modifier in the reaction mixture in relation to the starting material in an amount of not less than 100 mol / kg 6. The method according to claim 5, characterized in that an aliphatic diamine is used as a modifier. 7. The method according to claim 6, characterized in that ethylene diamine is used as a modifier. 8. The method according to claim 6, characterized in that hexamethylenediamine is used as a modifier. 9. A filtering method, comprising contacting the flowing water with a filter material, characterized in that the use of a fibrous ion exchange filter material according to claims 1 to 4 and obtained by the method according to claims 5 to 8, wherein the filter layer or layers are characterized by a specific contact surface of the fibrous material with flowing water of at least 300 cm ² / cm ³ and the packing density of the filter layer or layers of material is in the range from 0.15 to 0.50 g / cm ³ . 10. The method according to claim 9, in which the filtration is carried out through several layers of filtering materials, at least one of which is composed of material according to claims 1-4. 11. The method according to claim 9, in which the filtration is carried out through several layers of filtering materials, at least two of which are composed of material according to claims 1-4.

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