Reduced renewable activated carbon and preparation method thereof

Abstract

The invention relates to the field of activated carbon preparation, in particular to reduced renewable activated carbon and a preparation method thereof. The activated carbon is modified through a chemical reduction method, and the surface of the activated carbon is modified to generate electron-rich functional groups, so that the activated carbon has super reduction capacity, can effectively desorb and decompose pollutants in the regeneration process, and has remarkable environmental protection benefits and industrial application prospects; the device is especially suitable for the fields of wastewater treatment, air purification, waste gas treatment, heavy metal adsorption and the like, can effectively remove harmful pollutants, has lower energy consumption, meets the environmental protection requirement, and has great market potential. The novel reduced renewable activated carbon has innovativeness and wide application potential.

Description

Technical Field

[0001] The present invention relates to the field of activated carbon preparation, and in particular to reduced regenerable activated carbon and a preparation method thereof. Background Art

[0002] As an important adsorption material, activated carbon has good adsorption properties and has been widely used in air purification, water treatment and other fields. However, the adsorption capacity of traditional activated carbon gradually decreases with the accumulation of pollutants during the adsorption process, and after the adsorption process, the regeneration of activated carbon is more difficult, usually requiring high temperature or high pressure conditions, which not only consumes a lot of energy, but also makes the regeneration process complex and inefficient, making it difficult to achieve industrial-scale application. Therefore, how to improve the regeneration efficiency of activated carbon while maintaining its adsorption properties has become a technical difficulty in the application of activated carbon. Traditional activated carbon preparation methods have also failed to effectively improve its reduction adsorption capacity for pollutants such as heavy metals and chlorides. There is an urgent need to develop an innovative modification technology that can both enhance the adsorption capacity of activated carbon and achieve efficient reduction and regeneration. Summary of the Invention

[0003] To address the above-mentioned existing technical problems, the present invention provides a reduced, renewable activated carbon and a method for its preparation. This method modifies the activated carbon surface to create electron-rich functional groups, enhancing the activated carbon's adsorption capacity while also enabling its regeneration. During the regeneration process, adsorbed pollutants can be reduced to harmless substances. This method has low energy consumption and is environmentally friendly, making it energy-efficient and suitable for industrial applications.

[0004] The present invention discloses a method for preparing reduced regenerable activated carbon, comprising the following steps:

[0005] S1 Activated carbon pretreatment: soak the activated carbon in an alkaline solution, wash it with deionized water until the pH value reaches 7-7.2, and then dry it;

[0006] S2 Chemical Reduction Treatment: The activated carbon pretreated in step S1 is placed in a reactor and subjected to gas replacement. After the gas replacement is completed, a reducing gas is introduced, and then the reaction temperature, pressure, and gas flow rate are controlled to perform reduction treatment to generate electron-rich functional groups on the surface of the activated carbon. After the reaction is completed, surface-modified activated carbon is obtained;

[0007] S3 post-treatment: The surface-modified activated carbon prepared in step S2 is rapidly cooled, washed, filtered, and dried to obtain reduced regenerable activated carbon.

[0008] Preferably, in the activated carbon pretreatment step S1, the alkaline solution is a sodium hydroxide solution with a molar concentration of 0.1 to 0.5 mol / L.

[0009] Preferably, in the activated carbon pretreatment step S1, the soaking time in the alkaline solution is 30 to 50 minutes.

[0010] Preferably, in the S2 chemical reduction treatment step, the reaction temperature is 300-600°C.

[0011] Preferably, in the S2 chemical reduction treatment step, the reaction pressure is 1 to 5 MPa.

[0012] Preferably, in the S2 chemical reduction treatment step, the reaction gas flow rate is 1 to 5 L / min.

[0013] Preferably, in the S2 chemical reduction treatment step, the reduction treatment time is 3 to 6 hours.

[0014] Preferably, in the S2 chemical reduction treatment step, the reducing gas is hydrogen or ammonia.

[0015] Preferably, in the S2 chemical reduction treatment step, the electron-rich functional group is an amino group, an amine group, a phenolic hydroxyl group or an imine group.

[0016] A reduced regenerable activated carbon is prepared by any of the above-mentioned methods for preparing reduced regenerable activated carbon.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The present invention provides a reduced regenerable activated carbon and a preparation method thereof. The activated carbon prepared by this preparation method has efficient adsorption performance and strong reducibility, and can quickly desorb and decompose pollutants through electrochemical or chemical reduction reactions during the regeneration process. This is because in the preparation process of activated carbon, a highly reducing chemical substance (such as hydrogen, ammonia, etc.) is used to reduce the activated carbon, so that electron-rich functional groups are formed on its surface, thereby improving its reduction adsorption capacity for certain pollutants (such as heavy metals, chlorides, etc.). During regeneration, the activated carbon can reduce the adsorbed pollutants to harmless substances through electrochemical reduction or chemical reduction reactions, thereby restoring its adsorption capacity, significantly improving the regeneration efficiency and service life of the activated carbon. This method has the advantages of low energy consumption and environmental protection, and can be suitable for large-scale industrial applications, solving the problems of high energy consumption and difficulty in complete decomposition of pollutants in the regeneration process of traditional activated carbon. DETAILED DESCRIPTION

[0019] The following examples are provided for a better understanding of the present invention and are not intended to limit the best mode of implementation. They do not limit the content and scope of protection of the present invention. Any product identical or similar to the present invention obtained by anyone under the guidance of the present invention or by combining the features of the present invention with other prior arts shall fall within the scope of protection of the present invention.

[0020] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in this field can be used. If the manufacturer of the reagents or instruments is not specified, they are all commercially available conventional reagents.

[0021] Example 1: A method for preparing reduced regenerable activated carbon, comprising the following steps:

[0022] S1 Activated carbon pretreatment: Soak the activated carbon in an alkaline solution, which is a sodium hydroxide solution with a molar concentration of 0.1 mol / L; after soaking for 30 minutes, wash with deionized water to a pH value of 7-7.2 and then dry it.

[0023] S2 Chemical reduction treatment: The activated carbon pretreated in step S1 is placed in a reactor and hydrogen is replaced three times. After the hydrogen replacement is completed, hydrogen is continuously introduced and the gas flow rate is controlled to be 1 L / min. Then, the reaction temperature is controlled to 300°C and the reaction pressure is 1 MPa, and chemical reduction treatment is carried out for 3 hours to generate electron-rich functional groups such as phenolic hydroxyl groups on the surface of the activated carbon. After the reaction is completed, surface-modified activated carbon is obtained.

[0024] S3 post-treatment: The surface-modified activated carbon prepared in step S2 is rapidly cooled, washed, filtered, and dried to obtain reduced regenerable activated carbon.

[0025] Example 2: A method for preparing reduced regenerable activated carbon, comprising the following steps:

[0026] S1 Activated carbon pretreatment: Soak the activated carbon in an alkaline solution, which is a sodium hydroxide solution with a molar concentration of 0.2 mol / L; after soaking for 35 minutes, wash with deionized water to a pH value of 7-7.2 and then dry it.

[0027] S2 Chemical reduction treatment: The activated carbon pretreated in step S1 is placed in a reactor and hydrogen is replaced three times. After the hydrogen replacement is completed, hydrogen is continuously introduced and the gas flow rate is controlled at 2L / min. Then, the reaction temperature is controlled at 350°C and the reaction pressure is 2MPa, and chemical reduction treatment is carried out for 3.5h to generate electron-rich functional groups such as phenolic hydroxyl groups on the surface of the activated carbon. After the reaction is completed, surface-modified activated carbon is obtained.

[0028] S3 post-treatment: The surface-modified activated carbon prepared in step S2 is rapidly cooled, washed, filtered, and dried to obtain reduced regenerable activated carbon.

[0029] Example 3: A method for preparing reduced regenerable activated carbon, comprising the following steps:

[0030] S1 Activated carbon pretreatment: Soak the activated carbon in an alkaline solution, which is a sodium hydroxide solution with a molar concentration of 0.3 mol / L; after soaking for 40 minutes, wash with deionized water to a pH value of 7-7.2 and then dry it.

[0031] S2 Chemical reduction treatment: The activated carbon pretreated in step S1 is placed in a reactor and hydrogen is replaced three times. After the hydrogen replacement is completed, hydrogen is continuously introduced and the gas flow rate is controlled to be 3L / min; then the reaction temperature is controlled to 400°C and the reaction pressure is 3MPa, and chemical reduction treatment is carried out for 4 hours to generate electron-rich functional groups such as phenolic hydroxyl groups on the surface of the activated carbon. After the reaction is completed, surface-modified activated carbon is obtained.

[0032] S3 post-treatment: The surface-modified activated carbon prepared in step S2 is rapidly cooled, washed, filtered, and dried to obtain reduced regenerable activated carbon.

[0033] Example 4: A method for preparing reduced regenerable activated carbon, comprising the following steps:

[0034] S1 Activated carbon pretreatment: Soak the activated carbon in an alkaline solution, which is a sodium hydroxide solution with a molar concentration of 0.4 mol / L; after soaking for 45 minutes, wash with deionized water to a pH value of 7-7.2 and then dry it.

[0035] S2 Chemical reduction treatment: The activated carbon pretreated in step S1 is placed in a reactor and hydrogen is replaced three times. After the hydrogen replacement is completed, hydrogen is continuously introduced and the gas flow rate is controlled to 4 L / min. Then, the reaction temperature is controlled to 500°C and the reaction pressure is 4 MPa, and chemical reduction treatment is carried out for 4.5 hours to generate electron-rich functional groups such as phenolic hydroxyl groups on the surface of the activated carbon. After the reaction is completed, surface-modified activated carbon is obtained.

[0036] S3 post-treatment: The surface-modified activated carbon prepared in step S2 is rapidly cooled, washed, filtered, and dried to obtain reduced regenerable activated carbon.

[0037] Example 5: A method for preparing reduced regenerable activated carbon, comprising the following steps:

[0038] S1 Activated carbon pretreatment: Soak the activated carbon in an alkaline solution, which is a sodium hydroxide solution with a molar concentration of 0.5 mol / L; after soaking for 50 minutes, wash with deionized water to a pH value of 7-7.2 and then dry it.

[0039] S2 Chemical reduction treatment: The activated carbon pretreated in step S1 is placed in a reactor and hydrogen is replaced three times. After the hydrogen replacement is completed, hydrogen is continuously introduced and the gas flow rate is controlled to be 5L / min. Then, the reaction temperature is controlled to 600°C and the reaction pressure is controlled to 5MPa, and chemical reduction treatment is carried out for 5h to generate electron-rich functional groups such as phenolic hydroxyl groups on the surface of the activated carbon. After the reaction is completed, surface-modified activated carbon is obtained.

[0040] S3 post-treatment: The surface-modified activated carbon prepared in step S2 is rapidly cooled, washed, filtered, and dried to obtain reduced regenerable activated carbon.

[0041] Example 6: A method for preparing reduced regenerable activated carbon, comprising the following steps:

[0042] S1 Activated carbon pretreatment: Soak the activated carbon in an alkaline solution, which is a sodium hydroxide solution with a molar concentration of 0.4 mol / L; after soaking for 45 minutes, wash with deionized water to a pH value of 7-7.2 and then dry it.

[0043] S2 Chemical reduction treatment: The activated carbon pretreated in step S1 is placed in a reactor and replaced with ammonia three times. After the ammonia replacement is completed, ammonia is continuously introduced and the gas flow rate is controlled at 4L / min. Then, the reaction temperature is controlled at 500°C and the reaction pressure is 4MPa, and chemical reduction treatment is carried out for 4.5h to generate electron-rich functional group amine on the surface of the activated carbon. After the reaction is completed, surface-modified activated carbon is obtained.

[0044] S3 post-treatment: The surface-modified activated carbon prepared in step S2 is rapidly cooled, washed, filtered, and dried to obtain reduced regenerable activated carbon.

[0045] Example 7: A method for preparing reduced regenerable activated carbon, comprising the following steps:

[0046] S1 Activated carbon pretreatment: Soak the activated carbon in an alkaline solution, which is a sodium hydroxide solution with a molar concentration of 0.2 mol / L; after soaking for 35 minutes, wash with deionized water to a pH value of 7-7.2 and then dry it.

[0047] S2 Chemical reduction treatment: The activated carbon pretreated in step S1 is placed in a reactor and replaced with ammonia three times. After the ammonia replacement is completed, ammonia is continuously introduced and the gas flow rate is controlled at 2L / min. The reaction temperature is then controlled at 350°C and the reaction pressure is 2MPa. Chemical reduction treatment is performed for 3.5h to generate electron-rich functional groups, imine groups, on the surface of the activated carbon. After the reaction is completed, surface-modified activated carbon is obtained.

[0048] S3 post-treatment: The surface-modified activated carbon prepared in step S2 is rapidly cooled, washed, filtered, and dried to obtain reduced regenerable activated carbon.

[0049] Example 8: A method for preparing reduced regenerable activated carbon, comprising the following steps:

[0050] S1 Activated carbon pretreatment: Soak the activated carbon in an alkaline solution, which is a sodium hydroxide solution with a molar concentration of 0.1 mol / L; after soaking for 30 minutes, wash with deionized water to a pH value of 7-7.2 and then dry it.

[0051] S2 Chemical reduction treatment: The activated carbon pretreated in step S1 is placed in a reactor and replaced with ammonia three times. After the ammonia replacement is completed, ammonia is continuously introduced and the gas flow rate is controlled to be 1L / min. Then, the reaction temperature is controlled to 300°C and the reaction pressure is 1MPa, and chemical reduction treatment is carried out for 3 hours to generate electron-rich functional group amino groups on the surface of the activated carbon. After the reaction is completed, surface-modified activated carbon is obtained.

[0052] S3 post-treatment: The surface-modified activated carbon prepared in step S2 is rapidly cooled, washed, filtered, and dried to obtain reduced regenerable activated carbon.

[0053] The performance of the reduced regenerable activated carbon prepared in Examples 1 to 8 was tested, and the test results are shown in the following table:

[0054]

[0055] From the test data in the above table, it can be seen that the moisture content of Examples 1 to 5 is constantly decreasing. The moisture content is crucial to the adsorption capacity of activated carbon. Higher moisture will occupy the pores of activated carbon; the ash content is also constantly decreasing. Similarly, higher ash will also reduce the adsorption capacity of activated carbon; the specific surface area and total pore volume are constantly increasing. The specific surface area is an important indicator for judging the adsorption capacity of activated carbon. The larger the surface area, the stronger the adsorption capacity; the total pore volume is the available pores, which affects the storage capacity of activated carbon, that is, the amount of material that can be adsorbed. The larger the total pore volume, the stronger the adsorption force; the pH values of Examples 1 to 5 are all around 7, indicating that activated carbon can effectively avoid corrosive effects on the treated substances during water treatment. In summary, among Examples 1 to 5, the activated carbon prepared in Example 4 has the best performance.

[0056] Examples 4 and 6 to 8 screened the electron-rich functional groups generated after chemical reduction treatment. From the test data in the above table, it can be seen that when the electron-rich functional groups are amino, amine, phenolic hydroxyl or imine groups, they all have good performance.

[0057] The activated carbons prepared in Examples 1 to 8 were subjected to regeneration experiments (electrochemical reduction or chemical reduction reaction) after pollutant adsorption, and the performance of the regenerated activated carbons was tested. The test results are shown in the following table:

[0058]

[0059] It can be seen from the test data in the above table that the moisture content after regeneration is generally low, indicating that the moisture is effectively removed during the regeneration process. Compared with the initial sample, the moisture content is significantly reduced, indicating that the moisture has been removed and is suitable for subsequent use. The ash content has decreased slightly, indicating that the ash content of the activated carbon has been removed to a certain extent during the regeneration process. The specific surface area and total control capacity of the activated carbon after regeneration are not much different from those before regeneration, and the pH value of the living carbon is still maintained at around 7.0, which shows that the regenerated activated carbon still has a strong adsorption capacity, and the activated carbon prepared in Examples 1 to 8 has regenerable properties.

[0060] The reduced regenerable activated carbon prepared in Examples 1 to 8 was subjected to multiple pollutant adsorption-regeneration cycles, and the number of regeneration cycles was recorded. The recorded data are shown in the following table:

[0061] Example 1 2 3 4 5 6 7 8 Number of cycles (times) 108 110 109 111 107 105 106 108

[0062] It can be seen from the data in the above table that the number of cycles of the reduced renewable activated carbon prepared in Examples 1 to 8 is greater than 100 times. It can be seen that the reduced renewable activated carbon prepared by the preparation method provided by the present invention has good regenerative properties and can basically be reused 100 times.

[0063] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A method for preparing reduced regenerable activated carbon, characterized in that: The following steps are involved: S1 Activated carbon pretreatment: soak the activated carbon in an alkaline solution, wash it with deionized water until the pH value reaches 7-7.2, and then dry it; S2 Chemical Reduction Treatment: The activated carbon pretreated in step S1 is placed in a reactor and subjected to gas replacement. After the gas replacement is completed, a reducing gas is introduced, and then the reaction temperature, pressure, and gas flow rate are controlled to perform reduction treatment to generate electron-rich functional groups on the surface of the activated carbon. After the reaction is completed, surface-modified activated carbon is obtained; S3 post-treatment: The surface-modified activated carbon prepared in step S2 is rapidly cooled, washed, filtered, and dried to obtain reduced regenerable activated carbon.

2. The method for preparing a reduced regenerable activated carbon according to claim 1, wherein: In the activated carbon pretreatment step S1, the alkaline solution is a sodium hydroxide solution with a molar concentration of 0.1 to 0.5 mol / L.

3. The method for preparing a reduced regenerable activated carbon according to claim 1, wherein: In the activated carbon pretreatment step S1, the soaking time in the alkaline solution is 30 to 50 minutes.

4. The method for preparing a reduced regenerable activated carbon according to claim 1, wherein: In the S2 chemical reduction treatment step, the reaction temperature is 300-600°C.

5. The method for preparing a reduced regenerable activated carbon according to claim 1, characterized in that: In the S2 chemical reduction treatment step, the reaction pressure is 1 to 5 MPa.

6. The method for preparing reduced regenerable activated carbon according to claim 1, wherein: In the S2 chemical reduction treatment step, the reaction gas flow rate is 1 to 5 L / min.

7. The method for preparing reduced regenerable activated carbon according to claim 1, wherein: In the S2 chemical reduction treatment step, the reduction treatment time is 3 to 6 hours.

8. The method for preparing reduced regenerable activated carbon according to claim 1, wherein: In the S2 chemical reduction treatment step, the reducing gas is hydrogen or ammonia.

9. The method for preparing reduced regenerable activated carbon according to claim 1, wherein: In the S2 chemical reduction treatment step, the electron-rich functional group is an amino group, an amine group, a phenolic hydroxyl group or an imine group.

10. Reduced renewable activated carbon prepared by the method for preparing reduced renewable activated carbon according to any one of claims 1 to 9.

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