RU2331581C1 - Carbonic mesoporous hemosorbent - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: carbonic mesoporous hemosorbent in the form of smoothed granules of the pseudo-spherical form is proposed. They consist of nano-dispersed of a carbon-carbon material in the form of a three-dimensional matrix, formed curved by layers of carbon of thickness 30-400 Å with radius of curvature 100-1600 Å, interplanar spacing of the layers of carbon is 3.48-3.60 Å which contains not less than 99.5% of carbon, and has density by helium of 1.80-2.08 g/cm³, iodine number 175-245 mg/g, on a specific area on BET 300-400 m²/g, the strength of granules during abrasion is not more than 0.30%/min, total volume of pores not less than 0.4 cm³/g, average diameter mesopore 4.0-20.0 nanometers, it is characterised by the fact that hemosorbent contains granules with the size of 0.3-1.0 mm, and the quantity of granules in the size of 0.3-0.5 mm makes 11-45%, and the content of ashes is no more than 0.08%. Hemosorbent possesses high chemical cleanliness, high mechanical durability of granules, smoothed surface of granules and absence of a dust that gives to it increased blood-compatibility and inertness in relation to the regular elements of blood and provides good dynamics of the sorption cleaning, and prevailing presence mesopore and transitional pores provide a high degree of cleaning blood from low and medium molecular toxins.

EFFECT: hemosorbent has high resistance to sterilisation; is nontoxic and is apyrogenous

3 ex, 1 tbl, 2 dwg

Description

The present invention relates to porous nanosized carbon materials used for hemosorption.

Carbon sorbents are substances that can remove toxic and ballast substances from blood, lymph or plasma by the hemosorption method, which is a universal method that allows the elimination of any substances from body fluids, especially medium-molecular compounds (toxins), which play a significant role in human disease.

At the stage of nucleation and development of hemosorption, the use of activated carbons containing a large amount of latent dust, with the ability to sinter in columns, the presence of a large number of minerals, often toxins, the destruction of blood cells, an excessively high sorbing ability, leading to the removal of not only toxic substances, but also vital, made it difficult to develop hemosorption as a substitute for hemodialysis and set the task of finding carbon sorbents that are free of the above disadvantages.

Known hemosorbent IGI obtained by processing coal. It is characterized by a stable porous structure in the entire volume of the spherical granule. Its varieties differ both in the advantage of micropores and in variants with a predominance of transition pores and macropores (Lopukhin Yu.M., Molodenkov MN Hemosorption. M: Medicine, 1985).

A drawback of IGI type coals is the relatively high ash content and the release of sodium, potassium, calcium, and other ions into the blood.

Known for the porous carbon material hemosorbent SKN-1K, which is a product of carbonization and subsequent activation of nitrogen-containing polymer resins (Nikolaev VG, Strelko VV Hemosorption on activated carbon. Kiev: Naukova Dumka, 1979).

The disadvantage of this hemosorbent is low mechanical strength, the presence of sharp edges on the contact surface with blood cells, the presence of latent dust, the relatively low proportion of mesopores, which together reduces its effectiveness when removing low and medium molecular weight toxins from the blood, leads to an increase in free hemoglobin, creates the possibility of dust penetration into the vital organs of the body.

Activated carbons produced by industry contain carbon (93-96%), hydrogen (0.5-2.0%), oxygen (4.0%), and, depending on the method of preparation and nature of the feedstock, 2% or more various impurities , including potentially toxic. All the main types of carbon hemosorbents obtained from fossil raw materials and materials of organic origin - wood, lignin, fruit seeds, nutshells, peat, sapropel - contain various amounts of mineral impurities in the form of salts of potassium, calcium, sodium, magnesium, iron, aluminum, silicon et al. (Lopukhin Yu.M., Molodenkov MN Hemosorption. M: Medicine, 1985). In the process of preparing carbon hemosorbents, all these substances pass into the oxide form and in small quantities can pass into the blood.

The use of wood chemical resins as binders to give strength to the sorbent leads to the possibility of the ingress of some toxic polymers onto the surface of carbonized granules and subsequently into the blood.

A new direction in the synthesis of carbon hemosorbent from natural gas and oil refining gases, as well as from oil and coal tar resins, is based on a two-stage transition of carbon to nanodispersed carbon compounds in the gas phase. At the first stage, as a result of reactions in the gas phase at a temperature of 1250-1500 ° C, hydrogen is lost with the formation of polycyclic aromatic hydrocarbons with a change in the H / C ratio from 0.5 to 0.125 and the formation of hydrocarbon molecules from C ₂₄ H ₁₂ to C ₁₉₃ H ₈₄ or more with the advent of nanosized pseudospherical carbon compounds ranging in size from 0.85 to 67 nm (Frenklach M. Reaction mechanism of soot formation in flames // J. Phys. Chem. Chem. Phys., 2000, v. 4, p. 2027 -2037). When granulated using a binder, these compounds form a carbon frame of a spherical shape with a size of 0.5-1.2 mm with a density of 0.2-0.4 g / cm ³ . In the second stage, due to the reaction of surface decomposition of propane, butane and other hydrocarbons on the surface of particles with a size of 0.85-67 nm at a temperature of 750-900 ° C, a carbon-carbon composite with a bulk density of 0.95-1.05 g / cm ³ which, after the activation reaction, turns into a mesoporous carbon substance - a carbon hemosorbent of the VNIITU class in the form of polished pseudospherical granules, consisting of nanodispersed carbon-carbon material in the form of a three-dimensional matrix formed by curved layers of carbon thickness minutes with 30-400 Å radius of curvature of 100-1600 Å, the interplanar spacing 3,48-3,60 Å layers of carbon, which has a density of helium 1,80-2,08 g / cm ^3.

The closest in essential features to the present invention is a hemosorbent based on dispersed carbon - a product of the processing of oil, coal and natural gas - VNIITU-1 (Specifications TU 9398-002-71069834-2004 Hemosorbent carbon in physiological saline sterile VNIITU-1, prototype )

The VNIITU-1 hemosorbent has high chemical purity, high mechanical strength of granules, a polished surface of granules and the absence of dust, which gives it increased blood compatibility and inertness with respect to blood cells and provides good dynamics of sorption purification, the predominant presence of mesopores and transition pores, which ensures a high degree of purification of blood from low- and medium-molecular toxins, has high resistance to sterilization, non-toxic, pyrogen-free.

Physico-chemical and biomedical characteristics of VNIITU-1

Total pore volume, cm ³ / g, not less 0.4 The specific surface adsorption of CTAB, m ² / g 65-125 Specific surface for nitrogen adsorption (BET), m ² / g 300-400 Iodine number, mg / g 175-245 Mass fraction of ash,%, no more 0.15 Mass fraction of total sulfur,%, no more 0.30 The number of granules with a diameter (0.5-1.0 mm),%, not less than 90 The number of granules with a diameter of less than 0.5 mm,%, not more than 10 pH of a solution of sodium chloride, equilibrium with hemosorbent 6.0-7.8 pellet strength during abrasion,% / min, no more 0.30

Impact on blood cells during blood supply

80-120 ml / min per 350 cm ³ sorbent

decrease in the number of leukocytes,%, no more 10 decrease in platelet count,%, no more fifteen growth of free hemoglobin,%, no more 6

Hemosorbent VNIITU-1 is effective as a means of detoxification of the blood of the body:

- in acute poisoning (industrial and household poisons, drugs, mushroom toxins, FOS);

- infectious diseases (meningococcal infection, viral hepatitis, tuberculosis);

- with endotoxemia (peritonitis, sepsis, burn disease, etc.);

- diseases of the liver and kidneys (acute hepatic-renal failure, chronic renal failure, renal and hepatic coma and recoma, biliary and portal cirrhosis);

- autoimmune and skin diseases (psoriasis, lupus erythematosus, rheumatoid arthritis, bronchial asthma, allergoses);

- neuropsychiatric diseases (alcoholism, schizophrenia, drug addiction, epilepsy).

The VNIITU-1 hemosorbent was widely used in the Russian Federation and the CIS countries with a high quality rating; it was awarded the Gold Medal of the First International Salon of Innovations and Investments in February 2001, Moscow, All-Russian Exhibition Center (VNIITU-1 advertising brochure of the Institute of Hydrocarbon Processing SB RAS, 2006 year).

The disadvantage of VNIITU-1 is the small fraction of granules with a size of less than 0.5 mm, which leads to an insufficient adsorption rate of various types of toxins, as well as the presence of residues of mineral impurities - 0.15%.

The aim of this invention is to create a modification of the hemosorbent VNIITU-1 - VNIITU-1M, which, while retaining all the advantages of VNIITU-1, provides additional properties that enhance its sorption activity to toxins for various special cases in clinical practice and almost completely eliminates the penetration of mineral impurities into the blood due to a decrease in their content in hemosorbent below 0.08%.

The proposed carbon mesoporous hemosorbent VNIITU-1M is polished pseudo-spherical granules consisting of a nanodispersed carbon-carbon material in the form of a three-dimensional matrix formed by curved carbon layers 30–400 Å thick with a radius of curvature of 100–1600 Å and an interplanar distance of carbon layers of 3.48 -3.60 Å, which contains not less than 99.5% carbon and not more than 0.08% ash, has a helium density of 1.80-2.08 g / cm ³ , iodine number 175-245 mg / g, specific BET surface 300-400 m ² / g, granule strength during abrasion not more than 0.30% / min, total the pore volume is not less than 0.4 cm ³ / g, the average mesopore diameter is 4.0–20.0 nm, granules 0.3–1.0 mm in size, and the number of granules 0.3–0.5 mm in size is 11 -45%.

Distinctive features of the proposed carbon mesoporous hemosorbent are the content of granules with a size of 0.3-1.0 mm, and the number of granules with a size of 0.3-0.5 mm is 11-45%, and the ash content is not more than 0.08%.

The proposed combination of essential features of the invention allows for a greater degree of extraction of various kinds of toxins from the blood and almost completely eliminates the penetration of mineral substances, often toxins, into the blood.

The overall increase in the fraction fraction of 0.3-0.5 mm in comparison with the prototype leads to an increase in the reaction rate of blood with the surface of the hemosorbent and provides a greater degree of extraction of toxins of low, medium and high molecular weight. This is due to two reasons: on the one hand, an increase in the fraction fraction of granules with a size of 0.3-0.5 mm leads to a decrease in the average diameter of the granules of the sorbent and an increase in the contact of the outer surface layer of the sorbent with blood by 1.5-2 times with one the same mass of carbon sorbent in the column, and on the other hand, the presence of a large number of mesopores and transition pores is a determining stage in the overall process of diffusion of the reacting blood substance to the pore surface, since the process proceeds in the region of internal diffusion. The combination of these factors increases the overall speed of the reaction of blood with the carbon surface and with the acceleration of sorption of toxins of small, medium and high molecular weight.

A decrease in the fraction fraction of 0.3-0.5 below 11% reduces the effect of adsorption of toxins, and an increase of over 45% is limited by the risk of sintering of the sorbent in the column.

The reduction in ash content compared with the prototype is provided by using pure sugar with a mineral content of 0.05% as a binder in the granulation process, instead of the previously used molasses with a mineral content of up to 2.0%. Using this technique provides a reduction in ash content to a level of not more than 0.08%, which almost completely eliminates the entry of potentially toxic substances into the blood.

Physico-chemical characteristics, as well as indicators of the structure and surface properties of the proposed hemosorbent, were determined by standard methods: interplanar distance — by a DRON-3 X-ray diffractometer, density on helium — a gas pycnometer on helium, carbon and ash contents — GOST 2408.1-95, GOST 25699.8-90 , iodine number - GOST 25699.3-90.

The change in sorption activity was evaluated on samples synthesized under the same conditions by varying the fractional composition using standard sieves according to the degree of change in the specific external surface according to CTAB (cetyltrimethylammonium bromide), m ² / g - GOST 25699.2-90, and the change in the total pore volume by water, cm ³ / g - GOST 17219-71.

Example 1. Obtaining hemosorbent includes the following stages:

1. Obtaining by thermo-oxidative pyrolysis at a temperature of 1400 ° C nanodispersed carbon with an average particle diameter of 64 nm, which granulation using a binder to form granules in the form of a carbon frame spherical shape with a size of 0.3-1.2 mm with a density of 0.2-0, 4 g / cm ³ .

2. Pyrolytic compaction of a granular carbon layer — obtaining particles forming granules on the surface at a temperature of 750-900 ° C due to the decomposition of propane and butane of a carbon-carbon composite with a bulk density of 0.95-1.05 g / cm ³ .

3. Activation in the environment of water vapor at 800 ° C (RF Patent 2275237, 04/27/06, "A method for producing a porous carbon-carbon material for the production of hemo- and enterosorbent").

4. Fractionation and hydromechanical processing of granules (RF Patent 2211727, 09/10/03, "A method for processing granules of carbon material for hemo- and enterosorption and a reactor for its implementation").

An aqueous solution of molasses with up to two percent mineral impurities was used as a binder during granulation.

Received hemosorbent VNIITU-1 (prototype) fractional composition: the number of granules 0.5-1.0 mm - 90%, the number of granules less than 0.5 mm - 10%. The surface measurement from the adsorption of CTAB was 95 m ² / g, the total pore volume of 0.40 cm ³ / g, the ash content of 0.15%.

Example 2. Under the conditions of experiment 1, the fractional composition was varied using sieves. A fraction was selected consisting of granules with a size of 0.3-1.0 mm, and the number of granules of 0.5-1.0 mm - 55%, the number of granules of 0.3-0.5 mm - 45%. The surface measurement from the adsorption of CTAB was 185 m ² / g, the total pore volume of 0.48 cm ³ / g, the ash content of 0.15%.

Example 3. In the conditions of experiment 2, the binder was replaced during the formation of nanodispersed carbon granules from an aqueous molasses solution with a mineral impurity content of up to two percent to an aqueous sugar solution with a mineral impurity content of up to 0.05%. The resulting substance - carbon hemosorbent VNIITU-1M - consists of granules with a size of 0.3-1.0 mm, and the number of granules of 0.5-1.0 mm - 55%, the number of granules of 0.3-0.5 mm . The surface measurement from the adsorption of CTAB was 185 m ² / g, the total pore volume of 0.48 cm ³ / g, the ash content of 0.08%.

The table shows the data of examples on the characteristics of the proposed hemosorbent, and figure 1 and 2 shows the outer surface of the polished granules and a scanning image of the surface structure in an electron microscope VNIITU-1 and VNIITU-1M.

Table Example granule content 0.3-0.5 mm,% granule content 0.5-1.0 mm,% Binder Beats adsorption surface of CTAB, m ² / g total pore volume, cm ³ / g ash content one 10 90 Molasses water solution 95 0.40 0.15 2 45 55 Molasses water solution 185 0.48 0.15 3 45 55 Water solution of sugar 185 0.48 0.08

The obtained carbon mesoporous hemosorbent, while retaining all the advantages of the VNIITU-1 hemosorbent, provides additional properties that enhance its sorption activity to toxins for various special cases in clinical practice and almost completely eliminates the penetration of mineral impurities into the blood due to a decrease in their content in hemosorbent below 0 , 08%.

Claims (1)

Carbon mesoporous hemosorbent in the form of polished pseudo-spherical granules consisting of a nanosized carbon-carbon material in the form of a three-dimensional matrix formed by curved carbon layers 30–400 Å thick with a radius of curvature of 100–1600 Å and an interplanar spacing of carbon layers of 3.48-3.60 Å, which contains at least 99.5% carbon, and has a helium density of 1.80-2.08 g / cm ³ , iodine number 175-245 mg / g, BET specific surface area 300-400 m ² / g, the strength of the granules with abrasion not more than 0.30% / min, the total pore volume of not less than 0.4 cm ³ / g, average the mesopore diameter is 4.0-20.0 nm, characterized in that the hemosorbent contains granules with a size of 0.3-1.0 mm, and the number of granules with a size of 0.3-0.5 mm is 11-45%, and the ash content is not more than 0.08%.

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