RU2736950C1 - Method of producing modified sorbent carbon materials based on fas-e activated carbon and carbopon-active activated nonwoven material with fixed resorcinol-formaldehyde airgel granules - Google Patents

Abstract

FIELD: life-saving methods and devices.SUBSTANCE: invention relates to modified sorbent carbon material intended for use as a sorbent layer of filtering-absorbing systems of individual respiratory protective devices. Material used is polymer crushed coal or activated nonwoven material, and adsorption additive is resorcinol-formaldehyde airgel.EFFECT: invention provides higher sorption capacity of carbon material and, as a result, higher protective properties of filtering-absorbing systems of individual respiratory protection.1 cl, 1 tbl, 1 dwg

Description

The invention can be used as a sorbing layer (charge) of filtering-absorbing systems (FPS), promising samples of filtering-type respiratory protection (RPE), integrated with a set of military equipment (KBEV).

At present, active carbons used in FPS RPE FT are obtained by carbonization and subsequent activation of organic substances of biological origin. In the production of modern FPSs of domestic and foreign production, as a rule, adsorbents with catalytic and chemisorption additives applied to them are used, which allows air purification from vapors and gases of harmful impurities not only on the basis of physical adsorption, but also using chemisorption and heterogeneous catalysis.

OJSC ENPO Inorganika has developed a unique technology for producing spherical carbon adsorbents from synthetic raw materials - furfural (particle diameter 0.5-3.0 mm). They are made by liquid molding of copolymers of furfural and some resins (epoxy, coal, etc.), added in an amount of 3-7% of the mass, followed by thermal curing. Carbonization and activation are carried out on rotating electric furnaces with a retort diameter of 325 mm.

The FAS-E polymer-based activated carbon obtained by this technology is the closest in its production characteristics to foreign analogues of Kureha Corp. (Japan) and Blucher GmbH (Germany), which are world leaders in the production of high-performance sorbents.

FAS-E coal can be used in any adsorption processes for the purification of gaseous and liquid media, human endoecology and nanotechnology [1].

It should be noted that, in spite of the extensive use of activated carbons in the composition of the sorbing layer (charge), one should not forget about the broad prospects for the use of activated carbon fibrous materials.

Activated carbon fibers (ACF) are the third form of active carbons with high specific activity and a large volume of micropores.

Carbon fibers are usually obtained by thermal treatment of chemical or natural organic fibers, in which mainly carbon atoms remain in the fiber material, which are combined into microscopic crystals aligned parallel to each other. The alignment of the crystals gives the fiber greater tensile strength.

Heat treatment consists of several stages. The first of them is the oxidation of the original fiber (polyacrylonitrile, viscose, cellulose hydrate) in air at a temperature of 250 ° C for 24 hours. Ladder structures are formed as a result of oxidation. After oxidation, there is a stage of carbonization - heating the fiber in nitrogen or argon at temperatures from 800 to 1500 ° C. As a result of carbonization, the formation of graphite-like structures occurs. The heat treatment process ends with graphitization at a temperature of 1600-3000 ° C, which also takes place in an inert atmosphere. As a result of graphitization, the amount of carbon in the fiber is brought to 99%.

The activated carbon fibers obtained in this way consist of thin filaments with a diameter of 5 to 15 microns, have an extremely high heat resistance: under heat exposure up to 2000 ° C in the absence of oxygen, the mechanical characteristics of the fiber do not change. Carbon fibers can be produced in a variety of forms: chopped yarns, continuous yarns, woven and non-woven materials, they are resistant to aggressive chemical environments, but oxidize when heated in the presence of oxygen. Carbon fiber materials are effective at low concentrations (below the MPC).

At present, in the Russian Federation, carbon fiber materials are produced by JSC Prepreg-SKM, JSC NPK Khimprominzhiniring, SPC UVIKOM, LLC Argon, by M-Karbo and NPO Inorganika.

The special interest in activated carbon fibers from the point of view of respiratory protection arises due to their extremely high dynamics of sorption and dynamic activity.

The "M-Carbo" company has developed a carbon fiber of the "Carbopon-Active" brand, made on the basis of a fabric made of viscose technical thread (carbonization, hereinafter - activation), which can be used in:

- filter materials for traps of organic impurities, from technological solutions and wastewater (especially in the area of low concentrations);

- devices for the recovery of organic solvents (dichloroethane, gasoline, acetone, etc.);

- filters for the production of drinking water (VIP filters, post-treatment stage);

- sorption and filtering materials for the manufacture of personal protective equipment (SIZK and RPE) and overalls for work in contact with SDYAV;

- filter materials for smoking rooms; use in cigarette filters;

- highly efficient cleaning in the production of alcoholic beverages and citric acid [2].

All types of pores are developed in carbon adsorbents, which are most widely used in protective equipment: micropores, mesopores, and macropores. At low concentrations of vapors and gases (0.01-0.05 mg / l), their adsorption occurs by 95% in the volume of micropores and about 5% on the surface of mesopores. Sorption materials with a meso- and macroporous structure absorb vapors and gases of toxic substances (OM) less efficiently at low concentrations and cannot provide the required level of protective properties of a filtering type RPE.

To give them special properties and specific sorption activity, they are additionally modified. Modification can be carried out either by physical methods, for example, additional heat treatment of sorbents, or by chemical (electrochemical) treatment, for example, oxidation with nitric acid or impregnation with chemically active substances.

Thus, the technical solutions used in the development of the sorbing layer (charge) in particular and the personal protective equipment of the respiratory system of the filter type in general, directly depend on the properties and characteristics of active carbons or activated carbon fiber materials used in their development.

The sorbent layer of filtering-absorbing systems predetermines the combination of protective, physiological-hygienic and weight and size characteristics of the RPE FT.

To improve the protective and ergonomic properties of FPS, it is necessary to develop modern sorbent materials that do not have the drawbacks inherent in coal-catalysts and which could be used in promising samples of FP RPEs integrated with KBEV.

In addition, in the manufacture of modern filtering-absorbing systems of RPE FT, it is necessary to use new generation technologies, which make it possible to increase the protective and operational properties of protective equipment due to:

- reducing the weight and size characteristics of the FPS;

- improving the ergonomic properties of the FPS;

- increasing the efficiency of protection of the respiratory system of a serviceman from vapors of toxic substances;

- ensuring technological and raw material independence in the production of military products, in accordance with paragraphs "c" and "d" of Article 53 of the Military Doctrine of the Russian Federation of 2014 [3];

- compliance of the concept of development of the military-scientific complex of the Armed Forces of the Russian Federation for the period up to 2025 and the State Armament Program until 2027 [4].

Improvement of the protective and ergonomic properties of the FPS sorbing layer can be achieved by using highly porous nanostructured sorbing materials based on aerogels (AGs) with an increased microporous structure [5].

The preparation of aerogels is based on the sol-gel method [5], in the general case, which includes several stages.

At the first stage of the sol-gel synthesis, a sol (colloidal solution) of oxo or hydroxo compounds of metals is formed (a soluble salt of the corresponding metal or an organic element can be selected as a starting reagent) as a result of hydrolysis reactions of precursors.

At the second stage, as a result of polycondensation of hydrolysis products and the formation of M - OH - M and M - O - M bridging bonds (processes of olation and oxolation, respectively), a three-dimensional gel is formed that fills the entire volume and is called a lyogel. Next, aging is carried out (the process of hardening the gel framework), which may include further condensation, dissolution, redeposition of sol particles or phase transitions within the solid or liquid phases.

The third stage in the synthesis of aerogels is the so-called supercritical drying, during which the liquid component of the lyogel is removed from the system without disturbing the structure of the gel. Variations in the structure and properties of the resulting aerogels can occur due to the choice of the composition and concentration of the starting metal-containing compounds, as well as the composition of the solvent for supercritical drying.

Our literary studies did not find references to the development of modified sorbent carbon materials (MSUM) based on polymeric crushed coal of the FAS-E brand or an activated nonwoven material of the Karbopon-Active brand with fixed resorcinol-formaldehyde airgel granules.

The lack of a technology for the industrial production of modified sorbing carbon materials with fixed granules of highly porous nanostructured sorbing compounds based on aerogels, as well as special technological equipment necessary for these purposes, leads to the need to develop a laboratory method for obtaining these materials.

The technical objective of the invention is the development of an improved sorbing layer (charge), which makes it possible to increase the sorption characteristics and provide reliable protection of the respiratory system of a serviceman from vapors (gases) of toxic substances.

This task is achieved by applying a set of principles used in the creation of ICMS with fixed AG particles.

1. Application of highly porous nanostructured materials as a sorption additive (the principle of increasing the efficiency of the sorbing layer).

2. Use of materials with high ergonomic properties as a basis (the principle of ergonomics).

3. The principle of fixing the sorption additive by the sol-gel method (the principle of fixing the granules at a point).

On the basis of earlier studies [6], crushed coal of the FAS-E brand and an activated non-woven material of the Karbopon-Active brand were chosen as the base material for the creation of modified sorbing carbon materials. Carbon airgel based on resorcinol-formaldehyde airgel was chosen as an adsorption (additive) for fixing these materials in mesopores.

To obtain a prototype MSUM, crushed coal of the FAS-E brand with a grain size of 0.5 mm was used, and the carbon fiber of the Karbopon-Active brand was not subjected to additional changes. The fixation of the carbon airgel based on resorcinol-formaldehyde airgel in the mesopores of the FAS-E active carbon and the activated nonwoven material "Carbopon-Active" was carried out by impregnating them with a sol (sol-gel method).

To prepare the sol, it is necessary to dissolve 4.95 g of resorcinol (1,3-dihydroxybenzene) in 39 ml of acetonitrile (acetic acid nitrile), then add 6.75 ml of formaldehyde solution (formic aldehyde or methanal) and 0.338 ml of 38% hydrochloric acid, stir the reaction mixture for 15 minutes. The scheme of this reaction is shown in Figure 1.

After that, in a cylindrical polypropylene container with a volume of 5 ml with crushed coal of the FAS-E brand (in an amount of 2-2.5 ml or 2.4 g), pour 3 ml of the obtained sol, and in a cylindrical container with a volume of 50 ml with material of the brand "Carbopon- Active "(5 by 5 cm) pour 30 ml of sol.

Gelation in a cylindrical container with FAS-E carbon took place within 48 hours at a temperature of 20 ° C, and in a cylindrical container with a material of the "Carbopon-Active" brand for 1.5-2 hours at a temperature of 20 ° C. Then the gels are aged at 20 ° C for 7 days. After aging, the gels must be rinsed with isopropyl alcohol once a day for 5 days.

Supercritical drying in CO ₂ was carried out in a setup consisting of a Supercritical 24 high pressure CO ₂ pump (SSI, USA), a 50 ml steel reactor, and a BPR back pressure regulator (Goregulator, Waters, USA).

The materials obtained as a result of the sol-gel method were washed with liquid CO ₂ for 2 h at a temperature of 20 ° C and a pressure of 15 MPa, then the temperature in the reactor (autoclave) was increased to 50 ° C and the sample was washed with supercritical CO ₂ (15 MPa) for 2-2.5 hours. After that, the pressure in the heated autoclave was gradually (within 30-40 minutes) reduced to atmospheric pressure, after which the autoclave was cooled and opened.

The pyrolysis of materials impregnated with resorcinol-formaldehyde aerogels was carried out in an inert atmosphere (N ₂ ) in a quartz flow reactor at 1000 ° C, the temperature was raised to the specified one for 1.5-2 h and held for 4 h, after which the reactor was cooled to 20 ° FROM.

Modified sorbing carbon materials obtained with the use of resorcinol-formaldehyde airgel can increase the possibility of neutralizing OM vapors according to the principle of physical adsorption due to the presence in its composition of amorphous carbon (a-C) formed after pyrolysis of polymer (crushed) coal of the FAS-E grade or activated nonwoven material of the "Karbopon-Aktiv" brand impregnated with resorcinol-formaldehyde airgel.

These properties of the obtained MSUM are confirmed by their studies by the method of thermal desorption of adsorbate gas (nitrogen).

This method is intended for measuring the specific surface area of dispersed and porous materials, adsorbents, catalysts, pigments by thermal desorption of adsorbate gas in accordance with GOST 23401-90.

These studies were carried out on a specific surface area analyzer Sorbtometer-M (KATAKON, Russia), which is included in the state register of measuring instruments (certificate of GOSTANDART RF RU.E.31.060.A No. 8292) and is approved for use in the Russian Federation [7].

Table 1 shows the main results of the determination: specific surface area by the method (Brunauer-Emmett-Teller) BET; specific surface area of mesoporous particles by the comparative t-method; the volume of micropores by the Dubinin-Radushkevich method (TOZM).

Based on table 1, the following conclusions can be drawn:

- FAS-E coal modified with resorcinol-formaldehyde AG has the largest specific surface area of 1100.887 m ² / g and a micropore volume of 0.753 cm ³ / g.

- the largest specific surface area of mesopores 588.719 m ² / g is possessed by carbon-felt "Karbopon-Active", modified with resorcinol-formaldehyde airgel.

The average value of the measurement results of each adsorption isotherm of MSUM was taken as the measurement result, the deviation of which did not exceed 10%.

Based on the above studies, it can be concluded that MSUM obtained on the basis of crushed coal of the FAS-E brand impregnated with resorcinol-formaldehyde airgel and an activated non-woven material of the Karbopon-Active brand impregnated with resorcinol-formaldehyde airgel significantly increased their sorption capacity in comparison with the base material (coal FAS-E and carbon fiber "Karbopon-Active") due to their modification with resorcinol-formaldehyde airgel.

All this indicates that when using the obtained MSUM as a sorbing layer (charge), the protective properties of filtering-absorbing systems, personal protective equipment of the respiratory system of the filtering type from OM vapors will be increased according to the principle of physical adsorption.

List of sources used

1. Product catalog of JSC ENPO "Inorganica". Under. ed. N.K. Kulikov. - Elektrostal: 2019 .-- 35 p.

2. Catalog of products of the firm "M-Karbo". [Electronic resource]. -Access mode: https: m-carbo.ru

3. Military doctrine of the Russian Federation [Electronic resource].

- approved By the decree of the President of the Russian Federation on 12/30/14. - Access mode: http://www.rg.ru/2014/12/30/doktrina-dok.html

4. Site materials of the Department of Information and Mass Communications of the Ministry of Defense of the Russian Federation [Electronic resource]. - Access mode: https://function.mil.ru

5. Lermontov, S.A., Malkova, A.N., Sipyagina, N.A. [and etc.]. Aerogels - synthesis, properties and practical application: article / S.A. Lermontov, A.N. Malkova, N.A. Sipyagina // Collection of articles of the Institute of Physiologically Active Substances of the Russian Academy of Sciences dedicated to the 40th anniversary of the foundation: under total. ed. Corresponding Member Russian Academy of Sciences S.O. Bochurin. M .: Publishing house "Typography 24" 2018.208 p. - ISBN 978-5-00122-556-0.

6. Mukhin, V.M., Guryanov, V.V., Kurilkin, A.A., Alyabishev, SV. Activated carbons based on furfural copolymer for recovery of vapors of organochlorine solutions: article / V.M. Mukhin, V.V. Guryanov, A.A. Kurilkin, S.V. Alyabishev // Advances in chemistry and chemical technology: collection of articles. scientific. tr. M .: RCTU named after D.I. Mendeleev, volume 31. 2017. No. 9. From 83-85.

7. Operation manual // Analyzer of specific surface area "Sorbtometer-M". Closed Joint Stock Company "KATAKON". - Novosibirsk, 2013.20 p.

Claims (1)

Modified sorbent carbon material intended for use as a sorbent layer of filtering-absorbing systems of promising samples of personal respiratory protection of filtering type, characterized in that polymer crushed carbon or activated nonwoven material is used as a basis for creating this material, and as an adsorption additives - resorcinol-formaldehyde airgel.

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