CN113522237B - Preparation method of benzene series adsorption activated carbon and prepared benzene series adsorption activated carbon - Google Patents
Preparation method of benzene series adsorption activated carbon and prepared benzene series adsorption activated carbon Download PDFInfo
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Abstract
The invention belongs to the field of new materials and the technical field of environmental protection, and particularly relates to a preparation method of activated carbon for benzene series adsorption and an activated carbon material for benzene series adsorption prepared by the same. The preparation method comprises the following steps: (1) carrying out saturated adsorption treatment on the activated carbon by adopting toluene vapor; (2) grafting a silane coupling agent onto the activated carbon treated in the step (1) by adopting a gas-phase chemical reaction method; (3) and (3) regenerating and activating the activated carbon treated in the step (2) to obtain the activated carbon for benzene series adsorption. When the active carbon for benzene series adsorption is used for purifying and adsorbing a benzene series coexistence system, the mutual inhibition effect among coexistence components in the benzene series can be reduced, and the synergistic efficient purification of the benzene series-containing waste gas is realized; in addition, the prepared active carbon has good hydrophobic property, and the influence of humidity on the performance of the active carbon for adsorbing benzene series can be obviously reduced.
Description
Technical Field
The invention relates to the technical field of new materials and environmental protection, in particular to a preparation method of activated carbon for benzene series adsorption and an activated carbon material for benzene series adsorption prepared by the same.
Background
Volatile organic compoundsThe Substances (VOCs) are a large class of carbon-based chemical substances which are volatile at room temperature, the emission sources of the substances are widely distributed, and include various artificial sources (automobiles, garbage incineration, oil fume emission, paper making, printing, coating, food processing, paint drying, transportation, oil refineries, automobile manufacturing, metal degreasing, textile manufacturing, electronic assembly, solvents, cleaning products and the like) and natural sources (trees, flowers, plants, volcanic eruptions and the like), and the pollution caused by the substances is a common concern of all people. Most VOCs are toxic or can emit pungent odors that can not only cause haze, greenhouse effects, sick building syndrome, plant rot, climate change, etc., but also interact with other pollutants in the air (e.g., NO)x、SOxEtc.) to cause a chemical reaction resulting in the formation of secondary pollutants such as photochemical smog, tropospheric ozone, peroxyacetyl nitrate, secondary organic aerosols, etc.
In recent years, with the deep development of atmospheric pollution prevention and control attack and rigor war in China, the treatment of volatile organic compounds has become one of the environmental problems to be solved urgently in China. Benzene series as typical volatile organic compounds are widely existed in the production and life of people, and almost all industries relate to the use and emission of the benzene series. At present, the widely studied benzene series treatment methods mainly include two major types, namely a non-destructive method and a destructive method. Non-destructive methods include absorption, adsorption, condensation, membrane separation, and the like; destructive methods mainly include photocatalytic oxidation, incineration, catalytic incineration, ozone catalytic oxidation, non-thermal plasma oxidation, biodegradation, and the like. Among them, the adsorption technology has been widely used due to its high sensitivity and no adsorption selectivity, including its single use or its combined use with other processes.
At present, adsorbents widely used in the field of VOCs treatment mainly comprise two main types, namely activated carbon and molecular sieves, wherein the activated carbon is most widely applied. In the practical application process, although people generally think that the activated carbon has no selectivity, the activated carbon shows certain selectivity when adsorbing a benzene mixture due to the difference of the pore diameter of the activated carbon and the distribution of active groups such as carboxyl, hydroxyl and the like on the surface, so that the phenomena of mutual inhibition and competitive adsorption of benzene, toluene and xylene are caused. In the gas purification process, not only a certain pollutant is purified, but all pollutants are purified, so that the adsorption effect of the activated carbon is greatly reduced in the practical application process due to the phenomenon, or partial pollution factors cannot be sufficiently removed due to the mutual inhibition or competitive adsorption under the condition that adsorption sites are abundant, so that the adsorbent needs to be regenerated, and the effect and the service life of the activated carbon adsorbent are greatly reduced due to the phenomena. In addition, as the adsorption of water molecules can occupy adsorption sites, the gas humidity has a large influence on the organic matter adsorption effect of the activated carbon, the hydrophobic modification of the activated carbon also has a very important significance on the efficient adsorption of the organic matter by the activated carbon in complex gas, and a plurality of related documents of hydrophobic activated carbon report the phenomenon.
There are many related patent applications in the literature for the preparation of hydrophobic activated carbon. 201911111738.4 (hydrophobic active carbon material, preparation method and application) uses silicic acid and acyl chloride as modifier to prepare hydrophobic active carbon; 201210476531.9 (a preparation method of a super-hydrophobic activated carbon modified material) and 201310223296.9 (a preparation method of super-hydrophobic activated carbon) adopt a chemical liquid phase impregnation method to carry out hydrophobic modification by trimethyl chlorosilane; 201310387341.4 (a super-hydrophobic active carbon modified material and a preparation method thereof) and 201611255627.7 (a method for preparing super-hydrophobic active carbon), a liquid phase grafting reaction method is adopted to graft hydrophobic materials containing components such as dimethyl silicone oil on the active carbon; 202010275754.3 (a preparation method of a hydrophobic protective layer on the surface of an activated carbon material) and 201410540567.8 (a preparation method of a hydrophobic activated carbon modified material) adopt a liquid-phase impregnation reaction method, and carry out hydrophobic modification on activated carbon by taking short-chain alkyl trimethoxy silane or long-chain alkyl trimethoxy silane as a modifier; 200810013780.8 (a hydrophobic honeycomb active carbon and its preparation method) adding hydrophobic modifier in the process of mixing the honeycomb active carbon to prepare hydrophobic honeycomb active carbon; 202010187049.8 (a hydrophobic activated carbon adsorbent for treating high-humidity VOCs and a preparation method thereof) adopts a liquid phase impregnation method and takes perfluoro-1-octanol as a modifier to prepare the hydrophobic activated carbon. The methods can effectively improve the hydrophobicity of the activated carbon material, but the methods are all liquid phase reactions, have the problems of complicated operation, introduction of harmful substances to the environment, generation of a large amount of waste liquid in the preparation process and the like, and do not mention the problem of inhibiting competitive adsorption phenomena among benzene series.
Disclosure of Invention
Aiming at the problems and the defects in the prior art, the invention aims to provide a preparation method of benzene series adsorption activated carbon and the prepared benzene series adsorption activated carbon.
In order to realize the purpose of the invention, the invention adopts the following specific technical scheme:
the invention provides a preparation method of activated carbon for benzene series adsorption, which comprises the following steps:
(1) carrying out saturated adsorption treatment on the activated carbon by adopting toluene vapor;
(2) grafting a silane coupling agent onto the activated carbon treated in the step (1) by adopting a gas-phase chemical reaction method;
(3) and (3) regenerating and activating the activated carbon treated in the step (2) to obtain the activated carbon for benzene series adsorption.
According to the above method for preparing the benzene-series adsorption activated carbon, preferably, the step (2) is specifically performed by: placing the activated carbon treated in the step (1) in a closed container containing liquid water and a liquid silane coupling agent, wherein the three parts of the activated carbon, the liquid water and the liquid silane coupling agent are not in contact with each other, and reacting at 95-110 ℃ for 0.5-10 h (although the three parts of the activated carbon, the liquid water and the liquid silane coupling agent are not in contact with each other, under the reaction condition of 95-110 ℃, water vapor volatilized from the liquid water in the closed container can be in contact with silane coupling agent vapor volatilized from the liquid silane coupling agent, the silane coupling agent vapor and the water vapor react to form silicon hydroxyl, the silicon hydroxyl can be in dehydration condensation with hydroxyl on the surface of the activated carbon to form chemical bond connection, so that the silane coupling agent is grafted to the surface of the activated carbon); or placing the activated carbon in a closed container containing water vapor and silane coupling agent vapor, and reacting for 0.5-10 h at the temperature of 95-110 ℃.
According to the above preparation method of the benzene-series-adsorbing activated carbon, preferably, the silane coupling agent is methyltrimethoxysilane or ethyltrimethoxysilane.
According to the above preparation method of the activated carbon for benzene series adsorption, preferably, the mass ratio of the silane coupling agent to the liquid water in the closed container is 1: (0.5 to 3).
According to the above method for preparing the benzene-series adsorption activated carbon, preferably, the specific operations of the regeneration and activation in the step (3) are: and (3) heating the activated carbon treated in the step (2) for 5-10 hours in air or nitrogen atmosphere at 150-180 ℃.
According to the above method for preparing the benzene series adsorption activated carbon, preferably, the step (1) of performing saturated adsorption treatment on the activated carbon by using toluene vapor comprises the following specific operations: putting activated carbon in a closed container containing liquid toluene, wherein the activated carbon is not in contact with the liquid toluene and is placed for 6-12 h at 10-40 ℃ (although the activated carbon is not in contact with the liquid toluene, toluene vapor volatilized from the liquid toluene can be in contact with the activated carbon and then diffused into pore channels of the activated carbon);
or placing the activated carbon in a closed container containing toluene vapor, and placing for 6-12 h at 10-40 ℃.
According to the above preparation method of the benzene series adsorption activated carbon, preferably, the benzene series is a mixture of any two or three of benzene, toluene and xylene.
According to the preparation method of the activated carbon for benzene series adsorption, preferably, in the step (1), the activated carbon needs to be washed and activated before being subjected to saturated adsorption treatment by using toluene vapor, wherein the activation treatment is to dry the washed activated carbon at 105 ℃ for 2 hours and then at 150-180 ℃ for 5-10 hours; the washing is to wash the activated carbon with distilled water for 2-3 times.
According to the above method for producing the benzene-based compound-adsorbing activated carbon, the activated carbon is preferably any commercially available type of activated carbon or a self-made activated carbon. More preferably, the activated carbon is shell activated carbon, wood activated carbon, or coal activated carbon.
The second aspect of the invention provides a benzene series adsorption activated carbon product prepared by the preparation method of the first aspect.
The third aspect of the invention provides an application of the benzene series adsorption activated carbon product in the second aspect in purifying benzene series-containing waste gas.
According to the above application, preferably, the benzene series is a mixture of any two or three of benzene, toluene and xylene.
Compared with the prior art, the invention has the following positive beneficial effects:
(1) because the actual benzene-containing waste gas is a coexistence system of any two or three of benzene, toluene and xylene, when the benzene-containing waste gas is purified by adopting the activated carbon, the benzene-containing waste gas has mutual inhibition, which is not beneficial to the purification of the waste gas and causes the occurrence of the short plate effect of the wooden barrel, thereby causing the waste of the activated carbon and the increase of the actual operating cost.
The adsorption mechanism of organic substances by activated carbon mainly includes a physical adsorption mechanism depending on the specific surface area of activated carbon and a partition mechanism depending on hydrophobic groups in activated carbon, generally as a result of the interaction of the two (see documents: Li X, Zhang L, Yang Z, et al: adsorption materials for Volatile Organic Compounds (VOCs) and the key factors for VOCs adsorption processes: A review [ J ]. Separation and Purification Technology,2020,235: 116213). However, for three benzene series, i.e. benzene, toluene and xylene, although the polarities of the three benzene series have certain differences, the three benzene series belong to substances with stronger hydrophobicity, i.e. the purpose of reducing the mutual inhibition effect among the three benzene series adsorption cannot be achieved in the aspect of hydrophobic group distribution; therefore, the interference in the aspect of physical adsorption is attempted, the accessibility of macromolecules is limited by utilizing the difference between molecular sizes through a channel effect, namely, the effective specific surface area capable of being used for xylene adsorption is indirectly reduced, and the effect of weakening the mutual inhibition effect is achieved.
Before grafting a silane coupling agent on the surface of active carbon, carrying out saturated adsorption treatment on the active carbon by using toluene vapor, wherein the toluene vapor saturated adsorption treatment protects pore channels with the pore diameter smaller than or equal to toluene molecules in the active carbon, so that the silane coupling agent is mainly deposited in pore channels with larger pore diameter in the active carbon in the vapor deposition modification process of the silane coupling agent, a large number of pore channels with the pore diameter smaller than or equal to the toluene molecules are reserved in the modified active carbon, and the adsorption of the active carbon on the toluene molecules or molecules smaller than the toluene molecules cannot be influenced by the pore channels with the pore diameter smaller than or equal to the toluene molecules; the molecular size of benzene is smaller than that of toluene, and the molecular size of xylene is larger than that of toluene, so that the mutual inhibition effect of various benzene series, particularly xylene and benzene in the adsorption process of the activated carbon to the benzene series is greatly reduced, and the adsorption capacity of the activated carbon to the benzene is enhanced; therefore, the activated carbon prepared by the method can reduce the mutual inhibition among coexisting components in the benzene series, and realize the synergistic efficient purification of the benzene series-containing waste gas.
(2) According to the invention, the silane coupling agent is grafted on the surface of the activated carbon, the introduction of the silane coupling agent can divide the large-aperture pore channels of the activated carbon, so that part of the large pore channels are changed into small pore channels, and simultaneously, a large amount of methyl is introduced on the surface of the activated carbon after the silane coupling agent is grafted, so that the hydrophobicity of the surface of the activated carbon is obviously enhanced, and the contact angle of the activated carbon to water is increased from the range of 24.0-105.8 degrees to 142.8-150.6 degrees. The hydrophobic group is introduced, so that the hydrophobic property of the activated carbon is remarkably improved, water molecules are difficult to enter an adsorption pore channel of the activated carbon, the influence of water vapor on the adsorption property of the activated carbon is reduced, the adsorption capacity of the activated carbon on target organic matters in a high-humidity environment is improved, and the phenomenon that the activated carbon is disintegrated due to the swelling of the activated carbon skeleton caused by the water vapor can be effectively avoided. In addition, a large amount of methyl or ethyl hydrophobic groups are introduced into the surface of the active carbon for benzene series adsorption, so that the distribution effect of the active carbon for benzene series adsorption is enhanced in the benzene series adsorption process, and the partial influence of the reduction of the specific surface area on the adsorption performance is compensated.
(3) The silane coupling agent is grafted to the surface of the activated carbon by adopting a gas-phase chemical reaction method, namely, in a closed container containing silane coupling agent steam and water vapor, the silane coupling agent steam and the water vapor react to form silicon hydroxyl, the silicon hydroxyl and hydroxyl on the surface of the activated carbon are subjected to dehydration condensation to form chemical bond connection, so that the silane coupling agent is grafted to the surface of the activated carbon; the gas diffusion of the gas phase reaction is good, the permeability is good, the active carbon pore canal can not be blocked, the gas can be diffused to the deep part of the active carbon pore canal, and the silane coupling agent can be grafted on the surface of the active carbon pore canal fully.
(4) The temperature of the gas-phase chemical reaction is controlled to be 95-110 ℃, and the temperature is lower than the boiling point of the toluene, so that the toluene escape from active carbon pore channels in the reaction process can be reduced, and the effect of protecting the pore channels with small pore diameters is achieved.
(5) When the activated carbon grafted with the silane coupling agent is subjected to regeneration activation, the reaction temperature is controlled to be 150-180 ℃, and is higher than the boiling point of toluene, so that the toluene can be fully desorbed in the regeneration activation process, and the pore channels of the activated carbon can be fully released.
(6) The preparation method of the activated carbon for benzene series adsorption provided by the invention is simple and convenient to operate, mild in reaction conditions and free of waste water and waste gas.
Drawings
FIG. 1 is an infrared spectrum of the benzene series adsorption activated carbon prepared by the present invention;
FIG. 2 is a graph showing the contact angle of activated carbon for benzene series adsorption to water prepared by the present invention;
FIG. 3 is a graph showing the results of the effects of the co-existing components on xylene adsorption during the adsorption of the activated carbon for benzene-based adsorption prepared in the present invention;
FIG. 4 is a graph showing the influence of the coexisting components on benzene adsorption during the adsorption of the activated carbon for benzene series adsorption prepared in accordance with the present invention;
FIG. 5 is a graph showing the effect of the co-existing components on toluene adsorption during the adsorption of the activated carbon for benzene-based adsorption prepared in the present invention;
FIG. 6 is a graph showing the adsorption results of the benzene-based compound-adsorbing activated carbon prepared according to the present invention on each component in the presence of three benzene-based compounds;
FIG. 7 is a graph showing the effect of the toluene vapor saturation adsorption treatment on the toluene adsorption performance of the activated carbon for benzene-based compound adsorption prepared.
Detailed Description
The present invention will be described in further detail with reference to specific examples, but the scope of the present invention is not limited thereto.
Example 1:
a preparation method of activated carbon for benzene series adsorption comprises the following steps:
(1) weighing 10g of commercial wood activated carbon (recorded as AC-1), washing with distilled water for 3 times, filtering, placing in a 105 ℃ forced air drying oven for constant temperature heating for 2h, and then raising the temperature to 150 ℃ for constant temperature drying for 10 h; placing the activated carbon in a closed container containing liquid toluene, wherein the activated carbon is not in contact with the liquid toluene and is placed for 12 hours at 10 ℃;
(2) transferring the activated carbon treated in the step (1) into a closed container containing 5g of methyltrimethoxysilane (liquid) and 5mL of water, wherein the activated carbon, the methyltrimethoxysilane (liquid) and the water are not contacted with each other and react for 10h at the constant temperature of 95 ℃;
(3) and (3) transferring the activated carbon treated in the step (2) into a drying oven filled with nitrogen atmosphere, heating at the constant temperature of 180 ℃ for 5h, taking out, sealing and storing to obtain the benzene series adsorption activated carbon (marked as Si-AC-1).
Example 2:
a preparation method of activated carbon for benzene series adsorption comprises the following steps:
(1) weighing 10g of commercial fruit shell activated carbon (recorded as AC-2), washing with distilled water for 2 times, filtering, heating in a 105 ℃ forced air drying oven at constant temperature for 2h, and then heating to 180 ℃ and drying at constant temperature for 5 h; placing the activated carbon in a closed container containing liquid toluene, wherein the activated carbon is not in contact with the liquid toluene and is placed for 6 hours at the temperature of 40 ℃;
(2) transferring the activated carbon treated in the step (1) into a closed container containing 10g of methyltrimethoxysilane (liquid) and 30mL of water, wherein the activated carbon, the methyltrimethoxysilane (liquid) and the water are not contacted with each other, and reacting for 0.5h at a constant temperature of 110 ℃;
(3) and (3) transferring the activated carbon treated in the step (2) into a forced air drying oven, heating at the constant temperature of 150 ℃ for 10h, taking out, sealing and storing to obtain the benzene series adsorption activated carbon (marked as Si-AC-2).
Example 3:
a preparation method of activated carbon for benzene series adsorption comprises the following steps:
(1) weighing 10g of commercial coal-based activated carbon (recorded as AC-3), washing with distilled water for 3 times, filtering, placing in a 105 ℃ forced air drying oven for constant-temperature heating for 2h, and then raising the temperature to 160 ℃ for constant-temperature drying for 7 h; placing the activated carbon in a closed container containing liquid toluene, wherein the activated carbon is not in contact with the liquid toluene and is placed for 9 hours at 25 ℃;
(2) transferring the activated carbon treated in the step (1) into a closed container containing 10g of ethyltrimethoxysilane (liquid) and 5mL of water, wherein the activated carbon, the ethyltrimethoxysilane (liquid) and the water are not in contact with each other and react for 5 hours at a constant temperature of 105 ℃;
(3) and (3) transferring the activated carbon treated in the step (2) into a forced air drying oven, heating at the constant temperature of 170 ℃ for 7h, taking out, sealing and storing to obtain the benzene series adsorption activated carbon (marked as Si-AC-3).
Example 4:
a preparation method of activated carbon for benzene series adsorption comprises the following steps:
(1) weighing 10g of commercial wood activated carbon, washing the wood activated carbon for 3 times by using distilled water, filtering, placing the wood activated carbon in a 105 ℃ forced air drying box for constant-temperature heating for 2 hours, and then raising the temperature to 170 ℃ for constant-temperature drying for 7 hours; placing the activated carbon in a closed container containing liquid toluene, wherein the activated carbon is not in contact with the liquid toluene and is placed for 10 hours at the temperature of 20 ℃;
(2) moving the activated carbon treated in the step (1) into a closed container containing 5g of methyltrimethoxysilane (liquid state) and 10mL of water, wherein the activated carbon, the methyltrimethoxysilane (liquid state) and the water are not contacted with each other, and reacting for 8h at a constant temperature of 100 ℃;
(3) and (3) transferring the activated carbon treated in the step (2) into a forced air drying oven, heating at the constant temperature of 160 ℃ for 8h, taking out, sealing and storing to obtain the activated carbon for benzene series adsorption.
Example 5:
a preparation method of activated carbon for benzene series adsorption comprises the following steps:
(1) weighing 10g of commercial wood activated carbon, washing the wood activated carbon for 3 times by using distilled water, filtering, placing the wood activated carbon in a 105 ℃ forced air drying box for constant-temperature heating for 2 hours, and then raising the temperature to 170 ℃ for constant-temperature drying for 7 hours; placing the activated carbon in a closed container containing toluene vapor, and placing for 10h at 25 ℃;
(2) transferring the activated carbon treated in the step (1) into a closed container containing methyltrimethoxysilane vapor and water vapor, and reacting at constant temperature of 100 ℃ for 8 h;
(3) and (3) transferring the activated carbon treated in the step (2) into a forced air drying oven, heating at the constant temperature of 160 ℃ for 8h, taking out, sealing and storing to obtain the activated carbon for benzene series adsorption.
Example 6:
a preparation method of activated carbon for benzene series adsorption comprises the following steps:
(1) weighing 10g of commercial wood activated carbon, washing the wood activated carbon for 3 times by using distilled water, filtering, placing the wood activated carbon in a 105 ℃ forced air drying box for constant-temperature heating for 2 hours, and then raising the temperature to 150 ℃ for constant-temperature drying for 10 hours; placing the activated carbon in a closed container containing liquid toluene, wherein the activated carbon is not in contact with the liquid toluene and is placed for 12 hours at 10 ℃;
(2) placing the activated carbon treated in the step (1) in a closed container containing water vapor and ethyl trimethoxy silane vapor, and reacting for 4 hours at 105 ℃;
(3) and (3) transferring the activated carbon treated in the step (2) into a drying oven filled with nitrogen atmosphere, heating at the constant temperature of 180 ℃ for 5 hours, taking out, sealing and storing to obtain the benzene series adsorption activated carbon.
Example 7:
a preparation method of activated carbon for benzene series adsorption comprises the following steps:
(1) weighing 10g of commercial wood activated carbon, washing the wood activated carbon for 3 times by using distilled water, filtering, placing the wood activated carbon in a 105 ℃ forced air drying box for constant-temperature heating for 2 hours, and then raising the temperature to 150 ℃ for constant-temperature drying for 10 hours; placing the activated carbon in a closed container containing toluene vapor, and standing at 25 ℃ for 8 h;
(2) transferring the activated carbon treated in the step (1) into a closed container containing 5g of methyltrimethoxysilane (liquid) and 5mL of water, wherein the activated carbon, the methyltrimethoxysilane (liquid) and the water are not contacted with each other and react for 10h at the constant temperature of 95 ℃;
(3) and (3) transferring the activated carbon treated in the step (2) into a drying oven filled with nitrogen atmosphere, heating at the constant temperature of 180 ℃ for 5 hours, taking out, sealing and storing to obtain the benzene series adsorption activated carbon.
Example 8:
the preparation method of the toluene-free pretreated benzene series adsorption activated carbon comprises the following steps:
(1) weighing 10g of commercial fruit shell activated carbon (recorded as AC-2), washing with distilled water for 2 times, filtering, heating in a 105 ℃ forced air drying oven at constant temperature for 2h, and then heating to 180 ℃ and drying at constant temperature for 5 h;
(2) transferring the activated carbon treated in the step (1) into a closed container containing 10g of methyltrimethoxysilane (liquid) and 30mL of water, wherein the activated carbon, the methyltrimethoxysilane (liquid) and the water are not contacted with each other, and reacting for 0.5h at a constant temperature of 110 ℃;
(3) and (3) transferring the activated carbon treated in the step (2) into a forced air drying oven, heating at the constant temperature of 150 ℃ for 10h, taking out, sealing and storing to obtain the benzene series adsorption activated carbon (marked as Si-AC-0).
The performance of the active carbon for benzene series adsorption prepared by the invention is detected as follows:
1. the infrared spectrum detection of the activated carbon for benzene series adsorption comprises the following steps:
the benzene-based adsorption activated carbon prepared in examples 1 to 3 of the present invention was detected by infrared spectroscopy, and the detection results are shown in fig. 1.
As is clear from FIG. 1, 1273cm appears in the infrared spectra of the activated carbon for benzene series adsorption prepared in examples 1 to 3-1Or 763cm-1Si-CH of (A)3Absorption peaks and 1015cm-1The Si-O absorption peak shows that the silane coupling agent is grafted to the activated carbon skeleton in a chemical bond mode.
2. The invention relates to a method for detecting the water contact angle of activated carbon for benzene series adsorption, which comprises the following steps:
the contact angles of the benzene-based adsorption activated carbons prepared in examples 1 to 3 of the present invention with water were measured, and the results are shown in fig. 2 and table 1.
TABLE 1 contact angle of activated carbon for benzene series adsorption prepared by the present invention to water
As can be seen from fig. 2 and table 1, the water contact angle of the modified three different activated carbons, namely the wood activated carbon, the shell activated carbon and the coal activated carbon, is significantly increased from 24.0 to 105.8 degrees of the original activated carbon to 142.8 to 150.6 degrees, indicating that the hydrophobicity of the modified activated carbon is significantly increased.
3. The invention discloses a detection method of benzene series adsorption effect of activated carbon for benzene series adsorption, which comprises the following steps:
(1) the detection of the adsorption effect of the activated carbon for adsorbing benzene series in the dual-component benzene series coexisting system comprises the following steps:
the experimental method comprises the following steps: the benzene-based adsorption activated carbon prepared in examples 1 to 3 of the present invention was placed in a xylene-toluene saturated vapor coexisting system, a xylene-benzene saturated vapor coexisting system, and a benzene-toluene saturated vapor coexisting system at 30 ℃ respectively, and after 12 hours of adsorption, each amount of benzene (mg) adsorbed by the benzene-based adsorption activated carbon in the coexisting system was measured by a carbon disulfide desorption-gas chromatography hydrogen flame ionization technique (national environmental protection standard HJ584-2010), and then the adsorption capacity (mg/g) of the benzene-based adsorption activated carbon in the coexisting system for each benzene-based was obtained by converting the amount of the benzene-based adsorption activated carbon in the present invention. Meanwhile, under the same experimental conditions, the benzene-based adsorption activated carbon prepared in examples 1 to 3 of the present invention was placed in a pure xylene saturated vapor system, a pure toluene saturated vapor system, and a pure benzene saturated vapor system, respectively, and after 12 hours of adsorption, the adsorption capacity (mg/g) of the benzene-based adsorption activated carbon of the present invention to pure xylene vapor, toluene vapor, and benzene vapor was calculated according to the same method as described above.
In a xylene-toluene saturated vapor coexisting system and a xylene-benzene saturated vapor coexisting system, the adsorption capacity of the activated carbon for benzene series adsorption to xylene vapor of the invention is divided by the adsorption capacity of the activated carbon for benzene series adsorption to pure xylene vapor of the invention to obtain the ratio of the xylene adsorption capacity in the coexisting system to the xylene adsorption capacity in the single-component system, and the influence of the presence of toluene and benzene in the coexisting system on xylene adsorption is evaluated. The specific results are shown in FIG. 3.
In a benzene-xylene saturated vapor coexisting system and a benzene-toluene saturated vapor coexisting system, the adsorption capacity of the activated carbon for benzene series adsorption to benzene vapor is divided by the adsorption capacity of the activated carbon for benzene series adsorption to pure benzene vapor to obtain the ratio of the benzene adsorption capacity in the coexisting system to the benzene adsorption capacity in the single-component system, and the influence of the presence of xylene and toluene in the coexisting system on benzene adsorption is evaluated. The specific results are shown in FIG. 4.
In a toluene-xylene saturated vapor coexisting system and a toluene-benzene saturated vapor coexisting system, the adsorption capacity of the activated carbon for benzene series adsorption to toluene vapor of the invention is divided by the adsorption capacity of the activated carbon for benzene series adsorption to pure toluene vapor of the invention to obtain the ratio of the toluene adsorption capacity in the coexisting system to the toluene adsorption capacity in the single-component system, and the influence of the existence of xylene and benzene in the coexisting system on toluene adsorption is evaluated. The specific results are shown in FIG. 5.
In addition, in order to compare with the benzene series adsorption activated carbon prepared by the invention, the invention respectively adopts activated carbon AC-1, AC-2 and AC-3 to carry out comparison experiments, the comparison experiments are the same as the operation method of the experiments, the processing mode of the experimental results is the same, and the specific results are shown in figure 3, figure 4 and figure 5.
As can be seen from fig. 3, 4 and 5, in the benzene-based coexisting system, the presence of the coexisting components can significantly reduce the adsorption amount of any one of the benzene-based components by the activated carbon (including the activated carbon before and after modification), because the adsorption of the benzene-based component by the activated carbon is mainly based on physical adsorption, and the adsorption of any one of the benzene-based components can reduce the effective specific surface area of the activated carbon; however, in the benzene series coexisting system, the total adsorption capacity of the benzene series adsorption activated carbon prepared by the method is obviously higher than the adsorption capacity of the benzene series adsorption activated carbon in a single-component system to a single-component benzene series, because a large number of pore channels with the size less than or equal to that of toluene molecules are reserved in the activated carbon by carrying out toluene saturation pretreatment on the activated carbon when the benzene series adsorption activated carbon is prepared, the mutual inhibition effect among the coexisting components is obviously reduced, and the total adsorption capacity of the benzene series adsorption activated carbon in the coexisting system is better than the adsorption capacity of the single component, particularly in the benzene-xylene coexisting system. Therefore, the benzene-containing activated carbon for adsorption can reduce the mutual inhibition among the coexisting components in the benzene-containing compound and realize the efficient purification of the benzene-containing waste gas when the benzene-containing compound coexisting system is purified and adsorbed.
(2) The adsorption effect of the activated carbon for adsorbing the benzene series in the three-component benzene series coexisting system is detected as follows:
the experimental method comprises the following steps: the benzene series adsorption activated carbon prepared in example 1 of the present invention was placed in a xylene-toluene-benzene saturated vapor coexistence system at 30 ℃, and after 12 hours of adsorption, each amount (mg) of benzene series adsorbed by the benzene series adsorption activated carbon in the three-component coexistence system was measured by a carbon disulfide desorption-gas chromatography hydrogen flame ionization technique (national environmental protection standard HJ584-2010), and then the adsorption capacity (mg/g) of the benzene series adsorption activated carbon of the present invention to each benzene series in the coexistence system was obtained by converting the amount of the benzene series adsorption activated carbon of the present invention. Meanwhile, under the same experimental conditions, the activated carbon for benzene series adsorption prepared in example 1 of the present invention was placed in a pure xylene saturated vapor system, a pure toluene saturated vapor system, and a pure benzene saturated vapor system, respectively, and after 12 hours of adsorption, the adsorption capacity of the activated carbon for benzene series adsorption of the present invention to pure xylene vapor, toluene vapor, and benzene vapor was calculated according to the same method as described above.
In a xylene-toluene-benzene saturated vapor coexisting system, the ratio of the adsorption capacity of activated carbon for benzene series adsorption to xylene vapor of the invention to the adsorption capacity of activated carbon for benzene series adsorption to pure xylene vapor of the invention, the ratio of the adsorption capacity of activated carbon for benzene series adsorption to toluene vapor of the invention to the adsorption capacity of activated carbon for benzene series adsorption to pure toluene vapor of the invention, and the ratio of the adsorption capacity of activated carbon for benzene series adsorption to benzene vapor of the invention to the adsorption capacity of activated carbon for benzene series adsorption to pure benzene vapor of the invention were calculated, respectively, and the influence of activated carbon in a three-component coexisting system on the adsorption of the three substances was evaluated. See figure 6 for specific results.
In addition, in order to compare with the benzene series adsorption activated carbon prepared by the invention, the invention adopts the activated carbon AC-1 to carry out a comparison experiment, the operation method of the comparison experiment is the same as that of the experiment, the processing mode of the experiment result is the same, and the specific result is shown in figure 6.
As can be seen from FIG. 6, when three benzene series coexisted, the adsorption capacity of the original activated carbon (AC-1) to each benzene series was greatly reduced, and the adsorption capacities of benzene, toluene and xylene were only 8.18%, 12.83% and 39.13% of the pure substances, respectively; although the adsorption capacity of the modified activated carbon (Si-AC-1) to benzene, toluene and xylene is also greatly reduced, the adsorption capacity of the modified activated carbon to benzene, toluene and xylene is respectively 28.25%, 33.53% and 82.79% of that of a pure substance, and the mutual inhibition effect among three benzene series is obviously weakened.
4. Influence of toluene vapor saturation adsorption treatment on toluene adsorption performance of the prepared activated carbon for benzene series adsorption:
in order to examine the influence of the toluene vapor saturation adsorption treatment step on the toluene adsorption performance of the prepared activated carbon for benzene series adsorption, toluene adsorption experiments were carried out using the activated carbons prepared in example 2(Si-AC-2) and example 8(Si-AC-0) of the present invention.
The experimental method of the toluene adsorption experiment comprises the following steps: the benzene series adsorption activated carbon prepared in example 2 and example 6 of the present invention was placed in a pure toluene saturated vapor system at 30 ℃, and after 12 hours of adsorption, the amount (mg) of pure toluene vapor adsorbed by the benzene series adsorption activated carbon of the present invention was measured by a carbon disulfide desorption-gas chromatography hydrogen flame ionization technique (national environmental protection standard HJ584-2010), and then the adsorption capacity (mg/g) of the benzene series adsorption activated carbon of the present invention to pure toluene vapor in a coexisting system was obtained by converting the amount of the benzene series adsorption activated carbon of the present invention. See figure 7 for specific results.
As is clear from FIG. 7, the adsorption capacity of Si-AC-0 for toluene on the benzene-based adsorbent was 51.2mg/g, and the adsorption capacity of Si-AC-2 for toluene on the benzene-based adsorbent was 89.06 mg/g. Compared with the activated carbon Si-AC-0 for benzene series adsorption, the activated carbon Si-AC-2 for benzene series adsorption has the advantage that the adsorption performance of toluene is improved by 73.9%. The result shows that the toluene vapor is adopted to carry out saturated adsorption treatment on the activated carbon, so that the toluene adsorption capacity of the prepared activated carbon for benzene series adsorption can be improved. The reason is that the saturated adsorption treatment of the toluene vapor on the activated carbon can protect the pore channels with the pore diameter less than or equal to the toluene molecules in the activated carbon, and the blockage of the modifier on the pore channels of the activated carbon in the silane modification process is obviously reduced.
The above description is only exemplary of the present invention, and is not intended to limit the present invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are included in the scope of the present invention.
Claims (9)
1. A preparation method of activated carbon for benzene series adsorption is characterized by comprising the following steps:
(1) carrying out saturated adsorption treatment on the activated carbon by adopting toluene vapor;
(2) grafting a silane coupling agent onto the activated carbon treated in the step (1) by adopting a gas-phase chemical reaction method;
(3) carrying out regeneration activation on the activated carbon treated in the step (2) to obtain activated carbon for benzene series adsorption; the benzene series is any one or a mixture of any two or a mixture of three of benzene, toluene and xylene.
2. The method for preparing benzene-series activated carbon for adsorption according to claim 1, wherein the specific operation of step (2) is: placing the activated carbon treated in the step (1) in a closed container containing liquid water and a liquid silane coupling agent, wherein the activated carbon, the liquid water and the liquid silane coupling agent are not in contact with each other and react for 0.5-10 h at the temperature of 95-110 ℃; or placing the activated carbon in a closed container containing water vapor and silane coupling agent vapor, and reacting for 0.5-10 h at the temperature of 95-110 ℃.
3. The method for producing benzene-based adsorption activated carbon according to claim 2, wherein the silane coupling agent is methyltrimethoxysilane or ethyltrimethoxysilane.
4. The method for preparing the benzene-series-adsorbing activated carbon according to claim 2, wherein the mass ratio of the silane coupling agent to the liquid water in the closed container is 1 (0.5-3).
5. The method for preparing benzene-series activated carbon for adsorption according to claim 2, wherein the specific operation of regeneration and activation in step (3) is: and (3) heating the activated carbon treated in the step (2) for 5-10 hours in air or nitrogen atmosphere at 150-180 ℃.
6. The method for preparing benzene-series activated carbon for adsorption according to claim 5, wherein the step (1) of performing saturated adsorption treatment on activated carbon with toluene vapor comprises the following specific operations: placing the activated carbon in a closed container containing liquid toluene, wherein the activated carbon is not in contact with the liquid toluene and is placed for 6-12 hours at the temperature of 10-40 ℃; or placing the activated carbon in a closed container containing toluene vapor, and placing for 6-12 h at 10-40 ℃.
7. The method for preparing activated carbon for benzene series adsorption according to claim 6, wherein in the step (1), the activated carbon is washed and activated before saturated adsorption treatment is carried out on the activated carbon by using toluene vapor, and the activation treatment is to dry the washed activated carbon at 105 ℃ for 2 hours and then at 150-180 ℃ for 5-10 hours.
8. An activated carbon product for benzene series adsorption prepared by the preparation method of any one of claims 1 to 7.
9. The use of the benzene-containing activated carbon product according to claim 8 for purifying benzene-containing exhaust gas.
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