Modified activated carbon, preparation method and application of modified activated carbon in treatment of methyl mercaptan in sewage

Abstract

The invention provides modified activated carbon, a preparation method and application of the modified activated carbon in treatment of methyl mercaptan in sewage, and the preparation method comprises the following steps: crushing, screening, washing and drying an activated carbon material to obtain activated carbon particles; the preparation method comprises the following steps: dipping active carbon particles in a urea solution or a melamine solution, transferring the active carbon particles into a reaction kettle, carrying out a hydrothermal reaction, stably doping a nitrogen element into the active carbon, after the reaction is finished, washing a product obtained by the reaction to be neutral, drying, and carrying out heat treatment in a nitrogen atmosphere to obtain modified active carbon; in the preparation method provided by the invention, the physical and chemical properties of the activated carbon are optimized by adjusting the reaction conditions of the nitrogen doping process and the heat treatment process, such as the impregnation concentration, the impregnation time, the heat treatment temperature and time and the like, so that the modified activated carbon with the capacity of efficiently purifying the methyl mercaptan is obtained, and the adsorption capacity on the methyl mercaptan can reach more than 300mg / g; compared with unmodified activated carbon, the modified activated carbon is improved by 60% or above. The adsorption efficiency of the modified activated carbon on methyl mercaptan is greatly improved.

Description

Technical Field

[0001] The invention relates to the technical field of sewage treatment, and in particular to a modified activated carbon, a preparation method and application thereof in the treatment of methyl mercaptan in sewage. Background Art

[0002] Methyl mercaptan (CH3SH) is the main characteristic pollutant in odor. It has strong pungent odor, low olfactory threshold and high corrosion. It is a highly toxic sulfur-containing volatile organic compound (VOCs). At present, the removal technologies of methyl mercaptan mainly include oxidation, absorption, adsorption and biological methods. Among them, the adsorption method is widely used in odor treatment because of its simplicity and high efficiency. Activated carbon, as a commonly used adsorption material, has the advantages of stable performance and corrosion resistance, but it is frequently regenerated and replaced, and the deodorization cost is high. Summary of the invention

[0003] In view of the above problems existing in the prior art, the present invention provides a modified activated carbon, a preparation method and an application thereof, and through modification means, the adsorption capacity of activated carbon on methyl mercaptan is increased, its service life is extended, and the frequency of regeneration and replacement is reduced, so as to improve its purification effect on methyl mercaptan.

[0004] The specific content of the invention is as follows:

[0005] In a first aspect, the present invention provides a method for preparing modified activated carbon, the method comprising:

[0006] The activated carbon material is crushed, screened, washed and dried to obtain activated carbon particles with a particle size of 1 to 5 mm;

[0007] The activated carbon particles are immersed in a urea solution or a melamine solution with a concentration of 20% to 30%, and after 2 to 4 hours, they are transferred to a reaction kettle and subjected to a hydrothermal reaction at 80 to 100° C. After the reaction is completed, the reaction product is washed to neutrality and dried to obtain a modified activated carbon precursor;

[0008] The modified activated carbon precursor is placed in a nitrogen atmosphere and heat treated at 250-350° C. for 1-2 hours to obtain the modified activated carbon.

[0009] Optionally, the volume ratio of the activated carbon particles to the urea solution or the melamine solution is 1:5-10.

[0010] Optionally, the hydrothermal reaction time is 2 to 3 hours.

[0011] Optionally, the washing detergent is deionized water, and the washing times are 2-8 times.

[0012] Optionally, the heat treatment is performed in a tube furnace filled with nitrogen.

[0013] Optionally, the drying temperature is not higher than 100°C.

[0014] Optionally, the activated carbon material is a coconut shell activated carbon material or a coal-based activated carbon material, and the specific surface area of ​​the coconut shell activated carbon material or the coal-based activated carbon material is 700 to 1200 m 2 / g, iodine value is 1000mg / g.

[0015] In a second aspect, the present invention provides a modified activated carbon, which is obtained by the preparation method described in the first aspect.

[0016] In a third aspect, the present invention provides an application of modified activated carbon, wherein the modified activated carbon is obtained by the preparation method described in the first aspect, and the modified activated carbon is used as an adsorbent to remove methyl mercaptan in sewage.

[0017] Optionally, 1g of the modified activated carbon acts on a methyl mercaptan with an initial concentration of 10mg / m 3 The waste gas flow rate is 100mL / min, and within 240min, the adsorption rate of methyl mercaptan is 100%.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] The invention provides a method for preparing modified activated carbon, comprising: crushing, screening, washing and drying activated carbon materials to obtain activated carbon particles with a particle size of 1 to 5 mm; immersing the activated carbon particles in a urea solution or a melamine solution with a concentration of 20% to 30%, transferring the activated carbon particles to a reactor after 2 to 4 hours, performing a hydrothermal reaction at 80 to 100° C. to stably dope nitrogen elements in the activated carbon, washing the reaction product to neutrality after the reaction is completed, and drying to obtain a modified activated carbon precursor; placing the modified activated carbon precursor in a nitrogen atmosphere, and heat treating it at 250 to 350° C. for 1 to 2 hours to obtain the modified activated carbon.

[0020] In the preparation method provided by the present invention, by adjusting the nitrogen doping process and the reaction conditions of the heat treatment process, such as the impregnation concentration, the impregnation time, the heat treatment temperature and time, etc., the physical and chemical properties of the activated carbon are optimized to obtain a modified activated carbon with the ability to efficiently purify methyl mercaptan. Under the optimal modification conditions, the adsorption capacity of the activated carbon for methyl mercaptan can reach more than 300 mg / g, which is more than 60% higher than that of the unmodified activated carbon. The adsorption efficiency of the modified activated carbon for methyl mercaptan is greatly improved, thereby effectively extending the service life of the modified activated carbon, reducing the frequency of regeneration and replacement, and helping to save costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 The flowchart of the preparation method of modified activated carbon provided by the embodiment of the present invention is shown;

[0023] Figure 2 The TEM image of the modified activated carbon provided by the embodiment of the present invention is shown;

[0024] Figure 3 The XRD diagram of the modified activated carbon provided by the embodiment of the present invention is shown;

[0025] Figure 4 The figure shows the adsorption capacity test of the modified activated carbon provided in the embodiment of the present invention for methyl mercaptan. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means a limitation on the present invention and its application or use. Based on the embodiments of the present invention, any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior arts falls within the scope of protection of the present invention. In addition, all other embodiments obtained by ordinary technicians in this field without carrying out creative work belong to the scope of protection of the present invention.

[0027] In the embodiment, no specific experimental steps or conditions are indicated, and the operation or conditions of the conventional experimental steps described in the prior art in this field can be carried out. The reagents used and other instruments that do not indicate the manufacturer are conventional reagent products that can be obtained commercially. In addition, the accompanying drawings are only schematic diagrams of the embodiments of the present invention and are not necessarily drawn to scale. The same reference numerals in the figures represent the same or similar parts, and thus their repeated description will be omitted. Some block diagrams shown in the accompanying drawings are functional entities and do not necessarily correspond to physically or logically independent entities.

[0028] Technologies, methods, and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered as part of the description of the present invention.

[0029] In the description of the present invention, it should be understood that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0030] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0031] The following is a detailed description of a modified activated carbon, a preparation method and an application thereof provided by the present invention in conjunction with the accompanying drawings, tables and specific preparation examples:

[0032] In a first aspect, the present invention provides a method for preparing modified activated carbon. Figure 1 The flow chart of the preparation method of modified activated carbon provided by the embodiment of the present invention is shown as follows: Figure 1 As shown, the method includes:

[0033] S1. Crushing, screening, washing and drying the activated carbon material to obtain activated carbon particles with a particle size of 1 to 5 mm;

[0034] S2, immersing the activated carbon particles in a urea solution or melamine solution with a concentration of 20% to 30%, and after 2 to 4 hours, transferring them to a reaction kettle, and performing a hydrothermal reaction at 80 to 100° C., after the reaction is completed, washing the reaction product to neutrality, and drying to obtain a modified activated carbon precursor;

[0035] S3. placing the modified activated carbon precursor in a nitrogen atmosphere, and heat treating it at 250-350° C. for 1-2 hours to obtain the modified activated carbon.

[0036] In specific implementation, the activated carbon material is selected from coconut shell activated carbon material or coal-based activated carbon material, and the specific surface area of ​​the coconut shell activated carbon material or the coal-based activated carbon material is 700 to 1200 m 2 / g, iodine value is 1000mg / g. First, the activated carbon material is crushed and screened to obtain activated carbon particles with a particle size of 1 to 5mm. The crushing and screening treatment can effectively increase the attachment sites of the activated carbon to the modifier; since the ash component accounts for a large proportion (2%-3%), it will affect the loading amount of urea on the surface of the activated carbon. Therefore, before modifying the activated carbon, it must be washed with water to remove the ash components on its surface. Urea can be industrial urea, which is low in cost and can greatly reduce the modification cost.

[0037] In the specific implementation, the modifier is a urea solution or melamine solution with a concentration of 20% to 30%, and the volume ratio of the activated carbon particles to the urea solution or melamine solution is 1:5 to 10. During the modification process, the activated carbon particles are fully immersed in the urea solution or melamine solution, and the impregnation system is hydrothermally heated with the aid of a reactor. At 80 to 100°C, the nitrogen-containing groups in the urea solution or melamine solution are stably doped onto the activated carbon to form nitrogen-doped activated carbon; the adsorption performance of the activated carbon for methyl mercaptan after nitrogen doping treatment is improved by about 30% to 50%. After the reactor is depressurized and cooled, the impregnated activated carbon is filtered, washed with deionized water until neutral, and dried at no more than 100°C to obtain a modified activated carbon precursor.

[0038] In a specific implementation, the modified activated carbon precursor is further heat-treated in a tubular furnace filled with nitrogen to further improve the surface activity and adsorption performance of the activated carbon. The treated activated carbon exposes more active adsorption sites, and the adsorption performance of methyl mercaptan can be further improved by about 10% to 15%.

[0039] In the preparation method provided by the present invention, by adjusting the nitrogen doping process and the reaction conditions of the heat treatment process, such as the impregnation concentration, the impregnation time, the heat treatment temperature and time, etc., the physical and chemical properties of the activated carbon are optimized to obtain a modified activated carbon with the ability to efficiently purify methyl mercaptan. Under the optimal modification conditions, the adsorption capacity of the activated carbon for methyl mercaptan can reach more than 300 mg / g, which is more than 60% higher than that of the unmodified activated carbon. The adsorption efficiency of the modified activated carbon for methyl mercaptan is greatly improved, thereby effectively extending the service life of the modified activated carbon, reducing the frequency of regeneration and replacement, and helping to save costs.

[0040] In a second aspect, the present invention provides a modified activated carbon, which is obtained by the preparation method described in the first aspect.

[0041] In a third aspect, the present invention provides an application of modified activated carbon, wherein the modified activated carbon is obtained by the preparation method described in the first aspect, and the modified activated carbon is used as an adsorbent to remove methyl mercaptan in sewage.

[0042] In specific implementation, 1g of the modified activated carbon acts on methyl mercaptan with an initial concentration of 10mg / m 3 The waste gas flow rate is 100mL / min, and within 240min, the adsorption rate of methyl mercaptan is 100%.

[0043] In order to enable those skilled in the art to understand the present invention more clearly, the modified activated carbon, preparation method and application of the modified activated carbon in the treatment of methyl mercaptan in sewage described in the present invention are described in detail through the following examples.

[0044] Example 1

[0045] Coconut shell activated carbon is selected as the raw material, and activated carbon particles with a particle size of 1 to 5 mm are obtained through pretreatment operations such as crushing, screening, and deionized water washing.

[0046] The activated carbon particles were immersed in a 25% urea solution for 3 hours, and then transferred to a reactor for hydrothermal treatment at 90°C for 2.5 hours to dope nitrogen into the activated carbon to form a nitrogen-doped activated carbon precursor.

[0047] Subsequently, the nitrogen-doped activated carbon precursor was heat-treated at 300 °C in a nitrogen environment for 1.5 h to enhance its surface activity and adsorption performance.

[0048] The TEM and XRD patterns of the modified activated carbon prepared in Example 1 are as follows: Figure 2 , Figure 3 As shown, Figure 2 The TEM image of the modified activated carbon provided by the embodiment of the present invention is shown; Figure 3 The XRD diagram of the modified activated carbon provided in the embodiment of the present invention is shown. Figure 3 The XRD diagram shown shows that the activated carbon has two characteristic peaks at 23.5° and 43.4°, which correspond to the 002 crystal plane and 100 crystal plane of graphite, respectively, which means that the structure of the activated carbon is transformed from an amorphous state to a certain hierarchical order after treatment.

[0049] The adsorption capacity of the modified activated carbon prepared in Example 1 for methyl mercaptan reaches 280 mg / g, which is 55% higher than that of the unmodified activated carbon.

[0050] Example 2

[0051] Coal-based activated carbon is selected as the raw material, and activated carbon particles with a particle size of 1 to 5 mm are obtained through pretreatment operations such as crushing, screening, and deionized water washing.

[0052] The activated carbon particles were immersed in a 28% melamine solution for 2.5 hours, and then transferred to a reactor for hydrothermal treatment at 95° C. for 2 hours to form a nitrogen-doped activated carbon precursor.

[0053] The nitrogen-doped activated carbon precursor was then heat treated at 320°C in a nitrogen environment for 1 hour to adjust its physicochemical properties.

[0054] The adsorption capacity of the modified activated carbon prepared in Example 2 for methyl mercaptan reaches 310 mg / g, which is 65% higher than that of the unmodified activated carbon.

[0055] Example 3

[0056] Coconut shell activated carbon is selected, and after crushing, screening, washing and drying, activated carbon particles with a particle size of 1 to 5 mm are obtained.

[0057] The activated carbon was immersed in a 28% melamine solution for 2.5 hours, and then transferred to a reactor for hydrothermal treatment at 95° C. for 2 hours to form a nitrogen-doped activated carbon precursor.

[0058] The nitrogen-doped activated carbon precursor was then heat treated at 200°C, 250°C, 300°C, and 350°C in a nitrogen environment for 1 hour to adjust its physical and chemical properties, which are marked as A, B, C, and D, respectively.

[0059] Methyl mercaptan adsorption experiment example

[0060] The initial concentration of methyl mercaptan was 10 mg / m 3 The waste gas flow rate is 100mL / min, the amount of activated carbon A, B, C, and D is 1g, and the detection instrument is a gas chromatograph, and the instrument model is: Agilent GC-7860.

[0061] Figure 4 The adsorption capacity test of the modified activated carbon provided in the embodiment of the present invention for methyl mercaptan is shown. Figure 4 As shown, in Example 3, the preferred temperature is 300° C., which maintains 100% removal of methyl mercaptan for the longest time, about 3 hours, compared with the other three temperatures.

[0062] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification.

[0063] For the method embodiments, for the sake of simplicity, they are all described as a series of action combinations, but those skilled in the art should know that the present invention is not limited by the order of the actions described, because according to the present invention, some steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also know that the embodiments described in the specification are all preferred embodiments, and the actions and components involved are not necessarily required by the present invention.

[0064] The modified activated carbon, preparation method and application thereof in the treatment of methyl mercaptan in sewage provided by the present invention are introduced in detail above. Specific examples are used herein to illustrate the principle and implementation mode of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation mode and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for preparing modified activated carbon, characterized in that: The method comprises: The activated carbon material is crushed, screened, washed and dried to obtain activated carbon particles with a particle size of 1 to 5 mm; The activated carbon particles are immersed in a urea solution or a melamine solution with a concentration of 20% to 30%, and after 2 to 4 hours, they are transferred to a reaction kettle and subjected to a hydrothermal reaction at 80 to 100° C. After the reaction is completed, the reaction product is washed to neutrality and dried to obtain a modified activated carbon precursor; The modified activated carbon precursor is placed in a nitrogen atmosphere and heat treated at 250-350° C. for 1-2 hours to obtain the modified activated carbon.

2. The method for preparing modified activated carbon according to claim 1, characterized in that: The volume ratio of the activated carbon particles to the urea solution or the melamine solution is 1:5-10.

3. The method for preparing modified activated carbon according to claim 1, characterized in that: The hydrothermal reaction time is 2 to 3 hours.

4. The method for preparing modified activated carbon according to claim 1, characterized in that: The washing detergent is deionized water, and the washing times are 2 to 8 times.

5. The method for preparing modified activated carbon according to claim 1, characterized in that: The heat treatment was carried out in a tube furnace filled with nitrogen.

6. The method for preparing modified activated carbon according to claim 1, characterized in that: The drying temperature is not higher than 100°C.

7. The method for preparing modified activated carbon according to claim 1, characterized in that: The activated carbon material is a coconut shell activated carbon material or a coal-based activated carbon material, and the specific surface area of ​​the coconut shell activated carbon material or the coal-based activated carbon material is 700 to 1200 m 2 / g, iodine value is 1000mg / g.

8. A modified activated carbon, characterized in that The modified activated carbon is obtained by the preparation method described in any one of claims 1 to 7.

9. An application of modified activated carbon, characterized in that: The modified activated carbon is obtained by the preparation method described in any one of claims 1 to 7, and the modified activated carbon is used as an adsorbent to remove methyl mercaptan in sewage.

10. The use according to claim 9, characterized in that: 1g of the modified activated carbon The initial concentration of methyl mercaptan was 10 mg / m 3 The exhaust gas flow rate is 100mL / min, within 240min, The adsorption rate of methyl mercaptan was 100%.

Images