阅读说明：本技术 一种疏水活性炭的制备方法 (Preparation method of hydrophobic activated carbon ) 是由 宋肖肖 刘同浩 马乐 侯士峰 于 2021-08-17 设计创作，主要内容包括：本发明涉及一种疏水活性炭的制备方法,属于活性炭疏水改性领域,其特征在于,将活性炭首先进行热处理预处理,然后再与水玻璃混合液混匀,抽真空处理后抽滤并冲洗,调pH后陈化得负载二氧化硅的活性炭,最后经氟化处理得到氟化改性疏水活性炭；本发明的优点在于能够有效避免氟化过程中活性炭原结构的孔道坍塌影响吸附性能。(The invention relates to a preparation method of hydrophobic activated carbon, which belongs to the field of activated carbon hydrophobic modification and is characterized in that activated carbon is firstly subjected to heat treatment pretreatment, then is uniformly mixed with a water glass mixed solution, is subjected to vacuum pumping treatment, is subjected to suction filtration and washing, is subjected to pH adjustment and then is aged to obtain silicon dioxide-loaded activated carbon, and finally is subjected to fluorination treatment to obtain fluorinated modified hydrophobic activated carbon; the method has the advantage of effectively avoiding the influence on the adsorption performance caused by the collapse of the pore canal of the original structure of the active carbon in the fluorination process.)

1. A preparation method of hydrophobic activated carbon is characterized by comprising the following steps:

1) taking water glass, adding water to dilute to obtain a mixed solution A;

2) slowly heating the mixed solution A in the step 1) to boiling, cooling to room temperature, aging for a period of time, taking supernatant liquor, and filtering to obtain a mixed solution B;

3) putting the activated carbon into a tubular furnace, and carrying out heat treatment for a certain time under the protection of nitrogen to obtain solid C;

4) adding C into B according to a certain mass ratio, and uniformly stirring to obtain a mixed system D;

5) putting the mixed system D into a vacuum oven, and taking out after vacuumizing treatment;

6) magnetically stirring the vacuumized mixed system D at room temperature for a period of time, and then carrying out suction filtration and washing to obtain a solid E;

7) adding the solid E into deionized water with the same volume as the system D again, and dropwise adding sulfuric acid at the temperature of 20-60 ℃ while stirring until the system pH = 7; stopping stirring, standing and aging for a period of time, filtering and drying to obtain silicon dioxide-loaded activated carbon F;

8) putting the solid F in a closed tube furnace, introducing nitrogen firstly, introducing a fluorine-nitrogen mixed gas later, and performing fluorination treatment at the temperature of 100 ℃ and 150 ℃ for a certain time to obtain a product G;

9) and soaking the product G in HF for a period of time to remove silicon dioxide in the pore channel of the activated carbon, thereby obtaining the hydrophobic fluorinated activated carbon material.

2. The method for preparing hydrophobic activated carbon according to claim 1, wherein the water glass in the step 1) is 40% by weight.

3. The method for preparing hydrophobic activated carbon according to claim 1, wherein the heat treatment of step 3) is a high temperature treatment of 800 ℃.

4. The method for preparing hydrophobic activated carbon according to claim 1, wherein in the step 4), C: the mass ratio of B is 1:30-1: 100.

5. The method for preparing hydrophobic activated carbon according to claim 1, wherein the dropping speed of the sulfuric acid in the step 7) is 2 to 10 drops/min.

Technical Field

The invention relates to the field of active carbon hydrophobic modification, and particularly relates to a preparation method of hydrophobic active carbon.

Background

The active carbon has the advantages of developed void structure, large specific surface area, strong adsorption capacity, high removal rate, convenient recovery and the like, and is often used for treating low-concentration organic waste gas. However, the waste gas is often mixed with water vapor, and the presence of the water vapor reduces the equilibrium adsorption amount of VOC, which reduces the working efficiency of the adsorption tower, increases the operation cost, and reduces the recovery efficiency of the organic solvent. In order to solve the above problems, the activated carbon is usually subjected to hydrophobic modification treatment, typically by grafting a silane coupling agent or fluorination treatment.

In the fluorination treatment process of the prior art, carbon and fluorine react, and pi bonds of a carbon layer are broken to form new carbon-carbon bonds and fluorocarbon bonds. The old bond is broken, and the original structure of the activated carbon is changed in the process of forming the new bond, such as the collapse of a pore channel, the great reduction of the specific surface area and the like, so that the adsorption performance is influenced. Therefore, how to maintain the original structure in the fluorination process is a problem to be solved urgently.

Disclosure of Invention

The invention aims to solve the technical problem of the prior art, and provides a preparation method of hydrophobic activated carbon, which can effectively avoid the influence of the collapse of the pore canal of the original structure of the activated carbon on the adsorption performance in the fluorination process.

The technical scheme for solving the technical problems is as follows: a preparation method of hydrophobic activated carbon is characterized by comprising the following steps:

1) taking 40% water glass by mass, and adding water to dilute to obtain a mixed solution A;

2) slowly heating the mixed solution A in the step 1) to boiling, cooling to room temperature, aging for a period of time, taking supernatant liquor, and filtering to obtain a mixed solution B;

the boiling process can promote the complex silicic acid aggregates in the water glass solution to rapidly polymerize to form large network-shaped gel to wrap impurities in the solution and precipitate, so that the viscosity of the water glass is reduced;

3) putting the activated carbon into a tube furnace, and carrying out heat treatment at 800 ℃ for a certain time under the protection of nitrogen to obtain solid C;

impurities adsorbed in the active carbon pore canal are removed through heat treatment, so that the pore canal is richer and smoother;

4) adding C into B according to a certain mass ratio, and uniformly stirring to obtain a mixed system D; wherein, C: the mass ratio of B is 1:30-1: 100;

5) putting the mixed system D into a vacuum oven, and taking out after vacuumizing treatment;

the aim is to promote the escape of air in a system, particularly in the pore canal of the activated carbon, so that the water glass can be more quickly and fully filled in the pore canal of the activated carbon, and the adsorption of the activated carbon on the sodium silicate in the water glass is completed;

6) magnetically stirring the vacuumized mixed system D at room temperature for a period of time, and then carrying out suction filtration and washing to obtain a solid E;

the aim is to remove redundant water glass, only the water glass adsorbed by the active carbon is reserved, the water glass can be hydrolyzed in the following step to obtain silicon dioxide, and thus, after treatment, the active carbon cannot be wrapped by the silicon dioxide to influence the fluorination of the surface;

7) adding the solid E into deionized water with the same volume as the system D again, and dropwise adding sulfuric acid at the dropwise adding speed of 2-10 drops/min while stirring at the temperature of 20-60 ℃ until the system pH = 7; stopping stirring, standing and aging for a period of time, filtering and drying to obtain silicon dioxide-loaded activated carbon F;

8) putting the solid F in a closed tube furnace, introducing nitrogen firstly, introducing a fluorine-nitrogen mixed gas later, and performing fluorination treatment at the temperature of 100 ℃ and 150 ℃ for a certain time to obtain a product G; in the dry case, fluorine gas does not react with silica;

9) and soaking the product G in HF for a period of time to remove silicon dioxide in the pore channel of the activated carbon, thereby obtaining the hydrophobic fluorinated activated carbon material.

The invention has the beneficial effects that:

1) in the reaction process, sodium silicate (water glass) is adsorbed into the pore channel of the active carbon, so that the generation area of silicon dioxide is limited, and the active carbon is prevented from being coated by the silicon dioxide to influence the fluorination of the surface;

2) the silicon dioxide in the pore canal has a supporting function on the pore canal of the active carbon, so that the collapse of the pore canal of the active carbon in the fluorination process is avoided;

3) the carbon material prepared by the experimental scheme of the invention realizes the fluorination reaction on the surface of the activated carbon, so that the activated carbon has hydrophobicity, and simultaneously, the rich pore structure of the activated carbon is maintained.

Detailed Description

The principles and features of this invention are described below in conjunction with examples which are set forth to illustrate, but are not to be construed to limit the scope of the invention.

Example 1

The preparation method of the hydrophobic activated carbon comprises the following steps:

1) taking 1 part by mass of 40% water glass, and adding 3 parts by mass of deionized water for dilution to obtain a mixed solution A;

2) slowly heating the mixed solution A in the step 1) to boiling, cooling to room temperature, aging for 12h, taking supernatant, and filtering to obtain a mixed solution B;

3) putting the activated carbon into a tube furnace, and carrying out heat treatment at 800 ℃ under the protection of nitrogen to obtain solid C;

4) according to the mass ratio C: b =1:30, adding C into B, and stirring uniformly to obtain a mixed system D;

5) putting the mixed system D into a vacuum oven, vacuumizing for 2h, and taking out;

6) magnetically stirring the vacuumized mixed system D at room temperature for 10 hours, carrying out suction filtration and washing for 3 times to obtain a solid E;

7) the solid E was added again to the same volume of deionized water as in system D, and sulfuric acid was added dropwise at a rate of 2 drops/min at 20 ℃ with stirring to a system PH = 7. Stopping stirring, standing, aging for 12h, filtering and drying at 120 ℃ to obtain activated carbon F loaded with silicon dioxide;

8) putting the solid F in a closed tubular furnace, introducing nitrogen for 30min, introducing a fluorine-nitrogen mixed gas with the fluorine content of 5%, and carrying out fluorination treatment at 100 ℃ for 2h to obtain a product G;

9) and soaking the product G in HF for 2h to remove silicon dioxide in the pore channel of the activated carbon to obtain the hydrophobic fluorinated activated carbon material.

Example 2

1) Taking 1 part by mass of 40% water glass, and adding 3 parts by mass of deionized water for dilution to obtain a mixed solution A;

2) slowly heating the mixed solution A in the step 1) to boiling, cooling to room temperature, aging for 18h, taking supernatant, and filtering to obtain a mixed solution B;

3) putting the activated carbon into a tube furnace, and carrying out heat treatment at 800 ℃ under the protection of nitrogen to obtain solid C;

4) according to the mass ratio C: b =1:60, adding C into B, and stirring uniformly to obtain a mixed system D;

5) putting the mixed system D into a vacuum oven, vacuumizing for 4h, and taking out;

6) magnetically stirring the vacuumized mixed system D at room temperature for 18 hours, carrying out suction filtration and washing for 4 times to obtain a solid E;

7) the solid E was added again to the same volume of deionized water as in system D, and sulfuric acid was added dropwise at a rate of 6 drops/min at 40 ℃ while stirring to a system PH = 7. Stopping stirring, standing, aging for 18h, filtering and drying at 120 ℃ to obtain activated carbon F loaded with silicon dioxide;

8) putting the solid F in a closed tubular furnace, introducing nitrogen for 30min, introducing a fluorine-nitrogen mixed gas with the fluorine content of 5%, and performing fluorination treatment at 130 ℃ for 6h to obtain a product G;

9) and soaking the product G in HF for 4h to remove silicon dioxide in the pore channel of the activated carbon to obtain the hydrophobic fluorinated activated carbon material.

Example 3

1) Taking 1 part by mass of 40% water glass, and adding 3 parts by mass of deionized water for dilution to obtain a mixed solution A;

2) slowly heating the mixed solution A in the step 1) to boiling, cooling to room temperature, aging for 24h, taking supernatant, and filtering to obtain a mixed solution B;

3) putting the activated carbon into a tube furnace, and carrying out heat treatment at 800 ℃ under the protection of nitrogen to obtain solid C;

4) according to the mass ratio C: b =1:100, adding C into B, and stirring uniformly to obtain a mixed system D;

5) putting the mixed system D into a vacuum oven, vacuumizing for 6 hours, and taking out;

6) magnetically stirring the vacuumized mixed system D at room temperature for 24 hours, carrying out suction filtration and washing for 6 times to obtain a solid E;

7) the solid E was added again to the same volume of deionized water as that of the system D, and sulfuric acid was added dropwise at a rate of 10 drops/min at 60 ℃ while stirring to a system PH = 7. Stopping stirring, standing, aging for 24h, filtering and drying at 120 ℃ to obtain activated carbon F loaded with silicon dioxide;

8) putting the solid F in a closed tubular furnace, introducing nitrogen for 30min, introducing a fluorine-nitrogen mixed gas with the fluorine content of 5%, and performing fluorination treatment at 150 ℃ for 10h to obtain a product G;

9) and soaking the product G in HF for 6h to remove silicon dioxide in the pore channel of the activated carbon, thereby obtaining the hydrophobic fluorinated activated carbon material.

Comparative example 1

1) Weighing 1g of active carbon, putting the active carbon into a tube furnace, and carrying out heat treatment at 800 ℃ under the protection of nitrogen;

2) and (3) putting the activated carbon subjected to heat treatment in a closed tubular furnace, introducing nitrogen for 30min, introducing a fluorine-nitrogen mixed gas with the fluorine content of 5%, and performing fluorination treatment at 150 ℃ for 10h to obtain a final product.

The activated carbon as a raw material, the above examples and comparative examples were subjected to BET and water contact angle tests and formaldehyde removal rate tests at 90% humidity using a specific surface area tester and a contact angle tester, respectively. The test results are shown in Table 1.

Table 1 the examples and comparative examples were tested for each property as follows:

the test data in the table show that BET is reduced to different degrees after activated carbon is respectively fluorinated in examples 1 to 3 and comparative example 1, but the BET reduction range of the product of each example is far lower than that of the comparative example, which indicates that the technical scheme of the invention can largely maintain the pore structure of the activated carbon and effectively avoid the pore collapse of the activated carbon in the fluorination process; the water contact angle test data shows that the activated carbon can be changed from hydrophilic to hydrophobic after fluorination treatment; the formaldehyde removal rate at high humidity shows that the product of the invention has a higher removal rate, which is a result of the combined action of the hydrophobic active carbon and the intact pore structure.