RU2503496C2 - Granular modified nanostructured sorbent, method of its obtaining and composition for its obtaining - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: group of inventions relates to sorbents, which are applied in purification of water media from technogenic pollutants. Composition for preparation of granular nanostructured sorbent includes, wt %: glauconite - 20-50, intercalated graphite, which representing graphite bisulfate, - 1-5, bentonite clay - 40-70, modifier, selected from NaHCO₃ - 10, or KMnO₄ - 5, or NaCl - 8, and water. Method of granular nanostructured sorbent obtaining includes mixing powder-like initial components with the following addition of water until plastic mass is formed. Granulation of mass, drying of obtained granules are carried out by hot air at temperature not more than 100°C until content of water in granules is not more than 8%. After that, crushing of granules and further burning to conversion of intercalated graphite into thermally extended carbon are carried out at temperature not higher than 700°C for not more than 2 hours.

EFFECT: increase of sorption capacity and filtering ability of obtained sorbent.

9 cl, 2 tbl, 1 dwg, 3 ex

Description

The group of inventions relates to compositions and methods for producing modified sorbents containing nanostructured elements, can be used in the purification of aqueous media from industrial pollutants (heavy metals, petroleum products, organics, pesticides, radionuclides, etc.). When implementing the inventive method, a granular nanostructured modified sorbent is obtained, which is intended to be used as a filtering and sorption filling capable of replacing activated carbon, anionic-cationic resins, reverse osmosis membranes, etc.

Known methods for producing carbon sorbents based on the processing of carbon-containing raw materials (for example, peat) with subsequent granulation (Mukhin V.M., Tarasov A.V., Klushin V.N. Active coals of Russia. - M .: Metallurgy, 2000, 352 p. .).

The resulting sorbents, for example, activated carbon brand SKT, are characterized by low adsorption capacity and mechanical strength.

A known sorbent and method for producing inorganic sorbents based on zirconium dioxide in granular form, which consists in the fact that the sol of hydrated zirconia (GDC) containing 2-35 mol. % alumina with respect to zirconia, is dispersed dropwise into an ammonia solution, the obtained granules are washed with water and dried at 100-900 ° C for 6 hours. The introduction of alumina into zirconia in an amount of 2-35 mol leads to a significant (almost ten times) an increase in mechanical strength at high drying temperatures (see RF patent for invention No. 1293892). The known method allows to obtain spherical granules GDC with high mechanical strength at 200-900 ° C, which makes it possible to use sorbents in high-temperature cleaning processes. The mechanical and thermal properties of the obtained sorbent granules meet the requirements for catalysts and sorbents operating at high temperatures.

However, the use of zirconium dioxide as one of the starting components significantly increases the cost of the final product, which negatively affects its consumer qualities.

A known method of producing a granular sorbent, comprising mixing a base, for example a zeolite, with a basic aluminum salt pre-heated to 30-105 ° C as a binder, molding the mass, drying and heat treatment of the obtained granules. Sorbents obtained as a result of the application of the known method have high parameters of bulk and apparent density, and also have a lower total porosity (see USSR copyright certificate No. 494183).

However, for the implementation of the known method requires significant energy consumption, due mainly to the duration of the heat treatment of the granules, which leads to an increase in the cost of the final product.

A known method for producing granular aluminosilicate sorbents, including mixing solutions of water glass and sodium aluminate, crystallization, washing the obtained hydrogel from excess alkali, granulation and treatment with an alkaline solution, while the granular hydrogel is additionally subjected to treatment with 1-5% aluminum sulfate solution, followed by exposure to the solution ammonia and washing with distilled water (see USSR copyright certificate No. 835956).

The known method is technologically difficult to implement, requires the presence of certain chemicals, which in turn also negatively affects the price characteristics of the final product.

Known granular sorbent containing thermally expanded graphite (20-90 wt.%) And a component from the clay class (2-20%), as well as its production method, which consists in mixing thermally expanded graphite and clay, molding a mixture (see US patent No. 5607889 )

Known sorbent is characterized by low rates of sorption.

Known granular sorbent and method for its production, implemented during operation of the installation for granulating glauconite. The sorbent contains glauconite and a binder - a zirconium dioxide sol. The method consists in the following: the glauconite mined in the field is dried using a drying device, sieved, quartz impurities are removed, then sieved again, separating fractions of less than 40 microns. Larger fractions are returned for re-grinding. As a binder, a sol of zirconia with a concentration of 1.3 mol / L or an aluminophosphate sol of the same concentration is used. Glauconite concentrate with a fraction of less than 40 microns, a sol of zirconium dioxide with a concentration of 1.3 mol / l and water in a ratio of 1.75: 0.5: 0.5 or an aluminophosphate sol in a ratio of 1.75: 1.0 are placed in a mixer and produced mixing them for 10-15 minutes until a homogeneous mass with a moisture content of 32-34% is obtained. The homogenized mass is granulated using a screw granulator to obtain granules in the form of cylinders or balls 2 mm in diameter. The obtained granular material is dried at a temperature of 100 ° C for 1 hour. After drying, the obtained granules are calcined for 3 hours at a temperature of 400 ° C (using a zirconia sol) or at a temperature of 600 ° C (in the case of using aluminophosphate sol). During firing, green earth changes color from dark green to brown. The obtained calcined granules are cooled, for which they are blown (see RF patent for utility model No. 71562).

When implementing the known method, a significant amount of electricity is consumed, and the use of a zirconia sol as a binder in combination with the energy expended increases the cost of the final product many times, which is economically disadvantageous, especially when organizing industrial production.

The closest in technical essence to the claimed group of inventions is a granular nanosorbent and a method for its production, which includes mixing the starting components in the following ratio of components, wt.%: Bentonite clay - 10-40, glauconite - 10-50, thermally expanded carbon - 10-60 . followed by the addition of water to form a plastic mass, granulation of the mass, heat treatment of the obtained granules and cooling, the heat treatment includes drying the granules with infrared radiation at a temperature of 70-150 ° C and microwave heating of the granules previously placed in a closed thermally insulating volume of quartz ceramic to a temperature of 1000 ° C. During microwave processing, the granules are preliminarily placed in a closed thermally insulating volume, while overpressure of an inert gas in the closed volume is created, replacing the atmospheric air and residual moisture contained in the processed granules with an inert medium. The granules are cooled by air blowing at a temperature of 15-25 ° C (RF patent for the invention No. 2428249).

When implementing the known method, a significant amount of electricity is consumed, due to uncontrolled temperature in the microwave radiation zone, inhomogeneous firing of granules occurs, which leads to burnout (glass transition of granules) and not to burn out (raw granules), which ultimately affects the quality of the final product and a significant decrease in sorption properties.

The objective of the claimed group of technical solutions is to create an economical way to obtain a complex granular modified nanostructured sorbent based on intercalated graphite due to the optimal qualitative and quantitative selection of the starting components.

The technical result that can be obtained using the claimed group of inventions is to increase the sorption capacity and filtering ability of the modified nanostructured sorbent.

The specified technical result is achieved by the fact that the composition for the preparation of granular nanostructured sorbent, including glauconite, carbon and bentonite clay as a binder, according to the solution additionally contains a modifier that is NaHCO ₃ or KMnO ₄ , or NaCl, and intercalated graphite is selected as carbon at the following ratio of components, wt.%: glauconite - 20-50, intercalated graphite - 1-5, bentonite clay - 40-70, modifier - 5-10. The modifier is taken in the amount, wt.%: NaHCO ₃ - 10, or KMnO ₄ -5, or NaCl - 8. A method for producing a granular nanostructured sorbent, comprising mixing the starting components, including glauconite, carbon and bentonite clay, followed by the addition of water to form plastic mass, granulation of the mass, predrying the obtained granules and subsequent calcination, according to the solution of further starting components include a modifier, which is NaHCO ₃ or KMnO _4, or NaCl, and intercalated in graphite, etc. is selected as the carbon the initial components are taken in the ratio, wt.%: glauconite - 20-50, intercalated graphite - 1-5, bentonite clay - 40-70, modifier - 5-10, the granules are dried with hot air at a temperature of not more than 100 ° C and until the water content in the granules is not more than 8%, granules are crushed before firing, and the firing is carried out until intercalated graphite passes into thermally expanded carbon at a temperature of not more than 700 ° C for no more than 2 hours. After mixing the starting components, they are ground to a fraction of not more than 60 microns. The addition of water is carried out to its content in the plastic mass in the range of 38-42%. Granulation of the mass is carried out to obtain granules with a diameter of from 0.5 to 50 mm, a length of from 7 to 120 mm. After crushing the granules, sieving is carried out to isolate fractions of the granules 1-50 mm long and 1-50 mm wide. After firing, the granules are cooled by natural cooling to ambient temperature. A granular nanosorbent comprising glauconite, thermally expanded carbon and bentonite clay as a binder, characterized in that it further comprises a modifier, which is NaHCO ₃ , or KMnO ₄ , or NaCl in the following ratio of components, wt.%: Glauconite - 20-50, thermally expanded carbon - 1-5, bentonite clay - 40-70, modifier - 5-10. The granular nanosorbent contains a modifier in the amount, wt.%: NaHCO ₃ - 10, or KMnO ₄ - 5, or NaCl - 8.

The group of inventions is illustrated by the drawing, while the drawing shows a block diagram of a device with which the inventive method is implemented. The positions in the drawing indicate:

1. hopper for glauconite;

2. hopper for bentonite clay;

3. hopper for intercalated graphite;

4. hopper for one of the modifiers;

5. mixer;

6. granulator;

7. device for drying granules;

8. crusher;

9. vibrating screen;

10. roasting furnace;

11. filling device.

The method is as follows.

As initial components in the preparation of a granular modified nanostructured sorbent, glauconite, bentonite clay, intercollected graphite and one of the modifiers are used: NaHCO ₃ ; KMnO ₄ ; or NaCl. Glauconite in its natural structure is a greenish mineral. It is a clay mineral of variable composition with a high content of ferrous and trivalent iron, calcium, magnesium, potassium, phosphorus, and also contains more than twenty trace elements, including copper, silver, nickel, cobalt, manganese, zinc, molybdenum, arsenic, chromium, tin, beryllium, cadmium and others. All of them are in easily removable form of exchangeable cations, which are replaced by elements in excess in the environment. This property, as well as the layered structure, explains the high sorption properties in relation to oil products, heavy metals, radionuclides. At the same time, glauconite is characterized by a low percentage of desorption (removal from liquids or solids of substances absorbed by adsorption or absorption) and prolonged action, high heat capacity, ductility, etc. Glauconite is characterized by high ion exchange capacity (up to 15 20 mEq per 100 g of rock) and specific surface (up to 120 m ² / g), and as a result - a very significant absorption capacity. Being strong sorbents, glauconites absorb and transform into a state of inaccessible for plants salts of heavy metals and radionuclides (cesium-137 and strontium-90) contained in the soil. Bentonite clay used as a binder in the preparation of nanosorbent is clay containing at least 70% of the mineral of the montmorillonite group. Montmorillonite is a highly dispersed layered aluminosilicate in which due to non-stoichiometric substitutions of cations of the crystal lattice an excess negative charge appears, which is compensated by exchange cations located in the interlayer space. This is due to the high hydrophilicity of bentonite clay. When bentonite is mixed with water, it penetrates into the interlayer space of montmorillonite, hydrates its surface and exchange cations, which causes the mineral to swell. With further dilution with water, bentonite forms a stable viscous suspension with pronounced thixotropic properties. Montmorillonite has high cation exchange and adsorption properties. The last component used in the manufacture of a nanostructured sorbent is intercalated graphite, for example, which can be used, for example, the most studied graphite bisulfate (BG), since it is an intermediate product of thermally expanded carbon. The electrochemical synthesis of BG is based on the anodic oxidation of graphite in H ₂ SO ₄ solutions of a sufficiently high (~ 90-93%) concentration followed by hydrolysis of BG, the product of which is oxidized graphite (intercalated). NaHCO ₃ is a common powder. KMnO ₄ - crystalline in finely divided form. NaCl - in finely divided form.

All components necessary for the manufacture of a nanostructured modified sorbent are placed in powdered form in powdered storage containers 1-4 equipped with dispensers. Glauconite, bentonite clay, intercalated graphite, and one of the modifiers in powder form are mixed and ground additionally, then mixed and water is added until a plastic mass is obtained. The components are dosed into the mixer in the following ratio of components, wt.%: Bentonite clay - 40-70, glauconite - 20-50, intercalated graphite - 1-5, one of the modifiers: NaHCO ₃ - 10, KMnO ₄ - 5, NaCl - 8 The ranges of percentages of the components are determined by the expected conditions for the use of nanosorbent and the required degree of filtration and sorption. So, for example, for filtration and sorption of heavy metals, the starting components are metered and mixed in the following ratio: glauconite 30%, bentonite clay 64%, intercalated graphite 1%, modifier KMnO ₄ 5%, water 38-42%, until the plastic mass is formed. For the filtration and sorption of petroleum products in the following ratio: glauconite 30%, bentonite clay 55%, intercalated graphite 5%, modifier NaHCO ₃ 10%, water 38-42%, until the plastic mass is formed. Table 1 shows the change in the kinetics of sorption of heavy metals depending on the modifiers used and the almost constant ratio of the components (wt.%) Of the granulated nanostructured sorbent. Table 2 shows the change in the kinetics of phenol sorption with a change in the component ratios (wt.%) Of the granular nanostructured sorbent.

When solving water purification problems, various combinations of initial components and a modifier are also possible. For example, for water softening during its passing through the sorbent granules modified nanostructured starting components are mixed in the following ratio: 25% glauconite, 62% bentonite clay intercalated graphite 3%, NaHCO ₃ -10% modifier, 38-42% water, to form a plastic masses. To ensure sorption - glauconite 25%, 68% bentonite clay intercalated graphite 2% KMnO ₄ Modifier -5%, water 38-42%, to form a plastic mass. For iron removal - glauconite 35%, 57% bentonite clay intercalated graphite 3% -5 modifier KMnO _4%, water 38-42%, to form a plastic mass. The components are mixed with water in an automatic mode, determining the readiness of the plastic mass with a moisture meter or visually. Intercalated graphite is used in the crushed to finely dispersed fraction and mixed simultaneously with glauconite, finely dispersed bentonite clay, one of the modifiers, without adding water to form a homogeneous mass, then the resulting mass is placed in a mill and further crushed to obtain a homogeneous mass, again mixed and water is added until obtaining a homogeneous plastic mass, which is then subjected to granulation in a granulator. The shape and size of the granules is selected based on the required parameters of filtration and sorption of the resulting nanosorbent. Granules are obtained with a diameter of 1 to 50 mm, a length of 7 to 120 mm. Granulation is carried out, for example, using a horizontal single-screw extruder, the obtained granules after leaving the granulator are dried with hot air at a temperature of no higher than 100 ° C to a moisture content of not more than 8%. The dried granules are fed into a crusher, where they are crushed into irregularly shaped granules, having a size in the range from 1 to 50 mm, and also from 1 to 50 mm in length. As a result of crushing, various particle size distribution is formed. The granules are sieved through sieves having a size of 1 to 50 mm. The sifted granules are sorted according to particle size distribution and sent to the kiln at a temperature of not more than 700 ° C for no more than 2 hours. After heat treatment, the granules are cooled by natural cooling to ambient temperature, then the granules are packed in containers.

Thus, as a result of the implementation of the proposed method, a nanosorbent granular in the form of irregular granules is obtained, containing glauconite as the initial components, thermally expanded carbon formed from intercalated graphite at high firing temperatures, forming a developed nanostructure, bentonite clay throughout the granule volume (as a binder source component) and one of the modifiers. The percentage ratio of the components that make up the inventive nanosorbent is determined by the scope of its application and the necessary filtration and sorption characteristics.

Example No. 1 of a specific implementation.

The inventive method is implemented upon receipt of a nanostructured sorbent used in the purification of drinking water as part of a filter load of a household filter. Cadmium is present in the source water. The initial components used were: bentonite clay - 59%, glauconite - 30%, intercalated graphite - 3%, NaCl modifier - 8%, water 38-42%, before the formation of plastic mass. To obtain nanosorbent, the starting components were mixed in dry form, the resulting mass was placed in a mill and further crushed to obtain a homogeneous mass, mixed again and water was added until a homogeneous plastic mass was obtained, which was then granulated to give granules the shape of noodles with a diameter of 1.5 mm and a length of 100 mm The resulting noodles are dried with hot air to a moisture content of 8%. The dried noodles are sent to the grinder, where the granules of irregular shape of different particle size distribution are obtained. On a vibrating screen, the necessary granulometric composition of granules of 1.2-1.4 mm is sieved and isolated. It is sent to a kiln with a temperature of 650 ° C and burned for 1.5 hours. After firing, the granules cool to a temperature of 25 ° C. Chilled nanosorbent granules are packed for further sale.

Example No. 2 of a specific implementation.

The inventive method is implemented upon receipt of nanosorbent used in the purification of drinking water as part of the filter load of a household filter. Phenol is present in the source water. The initial components used are: bentonite clay - 6.5%, glauconite - 20%, intercalated graphite - 5%, NaHCO ₃ modifier - 10%, water 38-42%, until the plastic mass is formed. To obtain nanosorbent, the starting components were mixed in a dry form, the resulting mass was placed in a mill and further crushed to obtain a homogeneous mass, mixed again and water was added until a homogeneous plastic mass was obtained, which was then granulated to give granules the shape of noodles with a diameter of 2.5 mm and a length of 90 mm The resulting noodles are dried with hot air to a moisture content of 8%. The dried noodles are sent to the grinder, where the granules of irregular shape of different particle size distribution are obtained. On a vibrating screen, the necessary granulometric composition of granules of 2.1 - 2.4 mm is sieved and isolated. It is sent to a kiln with a temperature of 650 ° C and burned for 1.5 hours. After firing, the granules cool to a temperature of 25 ° C. Chilled nanosorbent granules are packed for further sale.

Example No. 3 of a specific implementation.

The inventive method is implemented upon receipt of nanosorbent used in the purification of drinking water as part of the filter load of a household filter. Iron is present in the source water. As starting components are used: bentonite clay - 69%, glauconite - 25% intercalated graphite - 1% KMnO ₄ Modifier -5%, water 38-42%, to form a plastic mass. To obtain nanosorbent, the starting components were mixed in a dry form, the resulting mass was placed in a mill and further crushed to obtain a homogeneous mass, mixed again and water was added until a homogeneous plastic mass was obtained, which was then granulated to give granules the shape of noodles with a diameter of 3.5 mm and a length of 80 mm The resulting noodles are dried with hot air to a moisture content of 8%. The dried noodles are sent to the grinder, where the granules of irregular shape of different particle size distribution are obtained. On a vibrating screen, the necessary granulometric composition of granules 3.2-4 mm is sieved and isolated. It is sent to a kiln with a temperature of 650 ° C and burned for 1.5 hours. After firing, the granules cool to a temperature of 25 ° C. Chilled nanosorbent granules are packed for further sale.

Table 1. The ratio of components and one of the modifiers wt.% Granular nanostructured sorbent Substance Preset concentration, mg / l The residual concentration after sorption, mg / l Glauconite Intercalated graphite Clay bentonite Modifier 28 3 59 NaHCO ₃ - 10 Cd 2 0.02 thirty 3 62 KMnS_four - 5 2 0,026 27 3 62 NaCl - 8 2 0.3 28 3 59 NaHCO ₃ - 10 Fe II 2 0.05 thirty 3 62 KMnO ₄ - 5 2 0,03 27 3 62 NaCl - 8 2 0.04 28 3 59 NaHCO ₃ - 10 Fe III 2 0.04 thirty 3 62 KMnO ₄ - 5 2 0.03 27 3 62 NaCl - 8 2 0.02 28 3 59 NaHCO ₃ - 10 Cu 2 0.005 thirty 3 62 KMnO ₄ - 5 2 0.01 27 3 62 NaCl - 8 2 0.08 28 3 59 NaHCO ₃ - 10 Zn 2 0.05 thirty 3 62 KMnO ₄ - 5 2 0.04 27 3 62 NaCl - 8 2 0.004

Table 2. The ratio of the components wt.% Granular nanostructured sorbent Substance Preset concentration, mg / l The residual concentration after sorption, mg / l Glauconite Intercalated graphite Clay bentonite fifty one 49 Phenol 2 0.21 fifty 2 48 2 0.12 fifty 3 47 2 0.0063 fifty four 46 2 0.0052 fifty 5 45 2 0.0045 47 3 fifty Phenol 2 0.21 42 3 55 2 0.12 37 3 60 2 0.0063 32 3 65 2 0.0052 27 3 70 2 0.0045 29th one 70 Phenol 2 0.12 28 2 70 2 0,085 27 3 70 2 0.058 26 four 70 2 0,042 25 5 70 2 0,034

Claims (9)

1. The composition for the preparation of granular nanostructured sorbent containing powdered glauconite, carbon and bentonite clay as a binder, characterized in that it further comprises a modifier selected from sodium bicarbonate NaHCO ₃ , or potassium permanganate KMnO ₄ , or sodium chloride NaCl, and as carbon selected intercalated graphite, which is graphite bisulfate, in the following ratio, wt.%:
glauconite 20-50 intercalated graphite 1-5 bentonite clay 40-70 modifier 5-10 and water taken in quantity 38-42 wt.% Of the sum of the powder components of the composition. 2. The composition according to claim 1, characterized in that the modifier is taken in quantity, wt.%:
NaHCO ₃ 10, or KMnO ₄ 5, or NaCl 8. 3. A method of obtaining a granular nanostructured sorbent, comprising mixing the starting components, including glauconite, carbon and bentonite clay, followed by the addition of water to form a plastic mass, granulating the mass, drying the obtained granules and subsequent calcination, characterized in that the starting components further include a modifier, which is NaHCO ₃ , or KMnO ₄ , or NaCl, and intercalated graphite, which is graphite bisulfate, is selected as carbon, while the initial the components are taken in the ratio according to claim 1, the granules are dried with hot air at a temperature of not more than 100 ° C and not more than 8% until the water content in the granules, granules are crushed before firing, and the firing is carried out before the iteration of graphite into thermally expanded carbon at a temperature no more than 700 ° C for no more than 2 hours 4. The method according to claim 3, characterized in that after mixing the starting components, they are ground to a fraction of not more than 60 microns. 5. The method according to claim 3, characterized in that the addition of water is carried out to its content in the plastic mass in the range of 38-42%. 6. The method according to claim 3, characterized in that the granulation of the mass is carried out to obtain granules with a diameter of from 1 to 50 mm, a length of from 7 to 120 mm. 7. The method according to claim 3, characterized in that after crushing the granules, sieving is performed to isolate fractions of granules 1-50 mm long and 1-50 mm wide. 8. The method according to claim 3, characterized in that after firing, the granules are cooled by natural cooling to ambient temperature. 9. A granular nanosorbent containing glauconite, thermally expanded carbon and bentonite clay as a binder, characterized in that it further comprises a modifier, and is obtained by the method described in claim 3.

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