A low-temperature, high-efficiency activated carbon composite material for formaldehyde adsorption and its preparation method

Abstract

This invention relates to the field of adsorption and filtration material preparation technology, specifically to an activated carbon composite material for low-temperature, high-efficiency formaldehyde adsorption and its preparation method. The method includes the following steps: S1, adding activated carbon to a strong oxidant solution; S2, washing and filtering the activated carbon treated in step S1 with deionized water until the filtrate is clear and transparent, and drying it in an oven at 105°C after washing; S3, preparing a formaldehyde low-temperature adsorption aid; S4, placing the dried activated carbon from step S2 in a tumbling mixer, and continuously spraying the formaldehyde low-temperature adsorption aid onto the surface of the activated carbon during stirring; S5, drying the activated carbon treated in step S4 in a temperature-controlled oven at 105°C. Compared with existing technologies, treating activated carbon with a strong oxidant introduces polar functional groups to the surface, which can form hydrogen bonds or weak chemical bonds with aldehydes.

Description

Technical Field

[0001] This invention relates to the field of adsorption and filtration material preparation technology, specifically to an activated carbon composite material for low-temperature and high-efficiency formaldehyde adsorption and its preparation method. Background Technology

[0002] Activated carbon, due to its high specific surface area and well-developed pore structure, is widely used for the physical adsorption of VOCs such as formaldehyde. However, at low temperatures (5~15℃), traditional activated carbon generally suffers from the following problems:

[0003] 1. Adsorption capacity decreased significantly (slow diffusion rate at low temperatures).

[0004] 2. The number of surface chemical groups is limited, resulting in insufficient affinity for polar aldehydes;

[0005] 3. An unreasonable pore size distribution (too low proportion of mesopores) leads to poor adsorption kinetics. Summary of the Invention

[0006] To overcome the shortcomings of existing technologies, this invention provides an activated carbon composite material for low-temperature, high-efficiency formaldehyde adsorption and its preparation method. The activated carbon is treated with a strong oxidant, introducing polar functional groups onto its surface. These groups can form hydrogen bonds or weak chemical bonds with aldehydes. A formaldehyde low-temperature adsorption aid, composed of polyamines and nano-silica sol, is introduced into the activated carbon. This simultaneously optimizes the pore size distribution of the activated carbon, increases the proportion of mesopores, and allows the introduction of polyamine groups to nucleophilically add to formaldehyde, thereby enhancing the adsorption capacity for formaldehyde molecules at low temperatures.

[0007] To achieve the above objectives, a method for preparing an activated carbon composite material for low-temperature, high-efficiency formaldehyde adsorption is designed, characterized by comprising the following steps:

[0008] S1. Add activated carbon to a strong oxidant solution, control the temperature at 60~80℃, and react for 30~60 minutes.

[0009] S2, Wash the activated carbon treated in step S1 with deionized water and filter it until the filtrate is clear and transparent. After washing, dry the filtrate in an oven at 105℃, controlling the moisture content to ≤3%.

[0010] S3 is formulated with formaldehyde low-temperature adsorption aids, including lysine, m-phenylenediamine, and nano-silica sol.

[0011] S4. Place the dried activated carbon from step S2 into a tumbling mixer. During the mixing process, formaldehyde low-temperature adsorption agent is continuously sprayed onto the surface of the activated carbon. The mass ratio of activated carbon to formaldehyde low-temperature adsorption agent is 1:1. The spraying process takes 5 to 10 minutes. After that, the mixer continues to stir for 20 to 30 minutes and then the carbon is left to stand for 1 hour.

[0012] S5. Use a temperature-controlled oven at 105℃ to dry the activated carbon processed in step S4, controlling the moisture content to ≤10%.

[0013] The strong oxidant solution in step S1 is a hydrogen peroxide solution with a concentration of 0.3M. The activated carbon impregnation time is 30-60 minutes, and the impregnation water bath temperature is controlled at 60-80℃.

[0014] In step S2, the water used to wash the activated carbon is deionized water, the activated carbon drying temperature is 105℃, and the moisture content of the dried activated carbon is ≤3%.

[0015] In the formaldehyde low-temperature adsorption aid in step S3, the mass concentration of lysine is 2-5 wt%, the mass concentration of m-phenylenediamine is 2-12 wt%, and the mass concentration of nano-silica sol is 0.5-2 wt%.

[0016] The formaldehyde low-temperature adsorption aid in step S3 includes lysine, m-phenylenediamine, and nano-silica sol.

[0017] In step S4, the formaldehyde low-temperature adsorption aid and activated carbon are mixed by tumbling spraying.

[0018] A low-temperature, high-efficiency activated carbon composite material for formaldehyde adsorption is prepared by any one of the above-mentioned methods.

[0019] Compared with existing technologies, this invention provides an activated carbon composite material for low-temperature and high-efficiency formaldehyde adsorption and its preparation method. The activated carbon is treated with a strong oxidant, introducing polar functional groups onto its surface. These groups can form hydrogen bonds or weak chemical bonds with aldehydes. A formaldehyde low-temperature adsorption aid, composed of polyamines and nano-silica sol, is introduced into the activated carbon, simultaneously optimizing the pore size distribution and increasing the proportion of mesopores. The introduction of polyamine groups onto the surface allows for nucleophilic addition of formaldehyde, enhancing the adsorption capacity for formaldehyde molecules at low temperatures. Compared with existing technologies on the market, this invention achieves a formaldehyde adsorption retention rate of ≥90% in low-temperature environments. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the modification mechanism of the material of the present invention.

[0021] Note: The activated carbon matrix is ​​presented with a honeycomb / microporous texture; the surface shows introduced functional groups; it shows that formaldehyde approaches and forms hydrogen bonds for adsorption, nucleophilic condensation.

[0022] Figure 2 This is a comparison chart of low-temperature adsorption curves. Detailed Implementation

[0023] The present invention will now be further described with reference to the accompanying drawings.

[0024] This invention provides an activated carbon material based on surface functional group modification, pore size distribution regulation, and composite additive guidance. The activated carbon composite material prepared according to the method of this invention can maintain high adsorption efficiency for formaldehyde even at low temperatures.

[0025] To achieve the above objectives, the technical solution adopted by this invention is: a low-temperature, high-efficiency activated carbon composite material for formaldehyde adsorption and its preparation method, comprising the following steps:

[0026] S1. Add activated carbon to a strong oxidant solution, control the temperature at 60~80℃, and react for 30~60 minutes.

[0027] S2, Wash the activated carbon treated in step S1 with deionized water and filter it until the filtrate is clear and transparent. After washing, dry the filtrate in an oven at 105°C, controlling the moisture content to ≤3%.

[0028] S3 is formulated with formaldehyde low-temperature adsorption aids, including lysine, m-phenylenediamine, and nano-silica sol.

[0029] S4. Place the dried activated carbon from step S2 into a tumbling mixer. During the mixing process, formaldehyde low-temperature adsorption agent is continuously sprayed onto the surface of the activated carbon. The mass ratio of activated carbon to formaldehyde low-temperature adsorption agent is 1:1. The absorption process takes 1 hour, the spraying process takes 5 to 10 minutes, and then the mixer continues to stir for 20 to 30 minutes.

[0030] S5. Use a temperature-controlled oven at 105℃ to dry the activated carbon processed in step S4, controlling the moisture content to ≤10%.

[0031] Preferably, the strong oxidant solution in step S1 is a 0.3M hydrogen peroxide solution.

[0032] Preferably, in step S1, the reaction time between the strong oxidant solution and activated carbon is 30 min, and the reaction temperature is 80 °C.

[0033] Preferably, in step S2, after washing the activated carbon with deionized water, the activated carbon is dried at a temperature of 105°C.

[0034] Preferably, in the formaldehyde low-temperature adsorption aid prepared in step S3, the mass concentration of lysine is 2wt%, the mass concentration of m-phenylenediamine is 10wt%, and the mass concentration of nano-silica sol is 0.5wt%.

[0035] Preferably, in step S4, during the process of spraying the formaldehyde low-temperature adsorption aid onto the activated carbon, the mass ratio of activated carbon to the formaldehyde low-temperature adsorption aid is 1:1.

[0036] Preferably, in step S4, the formaldehyde low-temperature adsorption agent is sprayed onto the activated carbon, and the spraying time is 5 minutes. After the spraying is completed, the activated carbon is stirred in the tumbler for another 30 minutes at a tumbling speed of 5 r / min.

[0037] Preferably, in step S5, the activated carbon dried at 105°C has a moisture content of 3% to 7%.

[0038] The present invention has the following beneficial effects:

[0039] 1. Hydrogen peroxide treatment of activated carbon introduces polar functional groups onto its surface, such as hydroxyl (-OH) and methoxy (-O-CH3). These groups can form hydrogen bonds or weak chemical bonds with aldehydes. Simultaneously, it optimizes the pore size distribution, increases the proportion of mesopores, and enhances the diffusion capacity of formaldehyde molecules at low temperatures. Low-temperature adsorption aids are also introduced, including lysine (an amine that provides an amino group to improve nucleophilic capture ability); m-phenylenediamine (an amine that provides an amino group to improve nucleophilic capture ability); and inorganic aids (silica sol, which further adjusts the pore size distribution and increases effective binding sites for formaldehyde). Compared with existing technologies on the market, this method can achieve a formaldehyde adsorption retention rate of ≥90% in low-temperature environments.

[0040] Example 1: Activated carbon was added to a hydrogen peroxide solution and reacted at 80°C for 30 minutes. The treated activated carbon was washed with deionized water and filtered until the filtrate was clear and transparent. After washing, the carbon was dried at 105°C, with the moisture content controlled to ≤3%. A formaldehyde low-temperature adsorption aid was prepared: lysine was added at 2 wt%, m-phenylenediamine at 10 wt%, and nano-silica sol at 0.5 wt%. The dried activated carbon was placed in a tumbling mixer. During the mixing process, the low-temperature adsorption aid was continuously sprayed onto the carbon surface at a mass ratio of 1:1. The spraying process lasted for 5 minutes, followed by 30 minutes of mixing at a frequency of 5 r / min. The treated activated carbon was dried in a temperature-controlled oven at 105°C, with the moisture content controlled to ≤10%.

[0041] Example 2: In this example, the formaldehyde low-temperature adsorption agent has a m-phenylenediamine mass concentration of 9.0 wt%, and the rest is the same as in Example 1.

[0042] Example 3: In this example, the formaldehyde low-temperature adsorption agent has a m-phenylenediamine mass concentration of 9.5 wt%, and the rest is the same as in Example 1.

[0043] Example 4: In this example, the formaldehyde low-temperature adsorption agent has a m-phenylenediamine mass concentration of 10.5 wt%, and the rest is the same as in Example 1.

[0044] Example 5: In this example, the formaldehyde low-temperature adsorption agent has a m-phenylenediamine mass concentration of 11.0 wt%, and the rest is the same as in Example 1.

[0045] The activated carbon composite materials from Examples 1 to 5 were tested for formaldehyde removal rate at room temperature (25°C) and low temperature (5°C), and the results are shown in Table 1.

[0046] Table 1

[0047] Example Formaldehyde removal rate at 25℃ (%) Formaldehyde removal rate at 5℃ (%) Formaldehyde adsorption retention rate % Example 1 92.2 88.3 95.8 Example 2 90.1 85.9 95.3 Example 3 91.3 86.2 94.4 Example 4 91.5 86.3 94.3 Example 5 90.6 85.7 94.6 Comparative Example 1 62.2 50.2 80.7

[0048] As shown in Table 1, the formaldehyde adsorption retention rate at low temperature in Examples 1 to 5 is all >90%. Compared with Comparative Example 1, the porous activated carbon composite material for low-temperature high-efficiency formaldehyde adsorption and its preparation method in this invention can effectively improve the adsorption effect of activated carbon on formaldehyde at low temperature.

Claims

1. A method for preparing a low-temperature, high-efficiency activated carbon composite material for formaldehyde adsorption, characterized in that, Includes the following steps: S1. Add activated carbon to a strong oxidant solution, control the temperature at 60~80℃, and react for 30~60 minutes. S2, Wash the activated carbon treated in step S1 with deionized water and filter it until the filtrate is clear and transparent. After washing, dry the filtrate in an oven at 105°C, controlling the moisture content to ≤3%. S3 is formulated with formaldehyde low-temperature adsorption aids, including lysine, m-phenylenediamine, and nano-silica sol. S4. Place the dried activated carbon from step S2 into a tumbling mixer. During the mixing process, formaldehyde low-temperature adsorption agent is continuously sprayed onto the surface of the activated carbon. The mass ratio of activated carbon to formaldehyde low-temperature adsorption agent is 1:

1. The spraying process takes 5 to 10 minutes. After that, the mixer continues to stir for 20 to 30 minutes and then the carbon is left to stand for 1 hour. S5. Use a temperature-controlled oven at 105℃ to dry the activated carbon processed in step S4, controlling the moisture content to ≤10%.

2. The preparation method of the activated carbon composite material for low-temperature high-efficiency formaldehyde adsorption according to claim 1, characterized in that: The strong oxidant solution in step S1 is a hydrogen peroxide solution with a concentration of 0.3M. The activated carbon impregnation time is 30-60 minutes, and the impregnation water bath temperature is controlled at 60-80℃.

3. The preparation method of the activated carbon composite material for low-temperature and high-efficiency formaldehyde adsorption according to claim 1, characterized in that: In step S2, the water used to wash the activated carbon is deionized water, the activated carbon drying temperature is 105℃, and the moisture content of the dried activated carbon is ≤3%.

4. The preparation method of the activated carbon composite material for low-temperature high-efficiency formaldehyde adsorption according to claim 1, characterized in that: In the formaldehyde low-temperature adsorption aid in step S3, the mass concentration of lysine is 2-5 wt%, the mass concentration of m-phenylenediamine is 2-12 wt%, and the mass concentration of nano-silica sol is 0.5-2 wt%.

5. The preparation method of the activated carbon composite material for low-temperature high-efficiency formaldehyde adsorption according to claim 1, characterized in that: The formaldehyde low-temperature adsorption aid in step S3 includes lysine, m-phenylenediamine, and nano-silica sol.

6. The method for preparing a low-temperature, high-efficiency activated carbon composite material for formaldehyde adsorption according to claim 1, characterized in that: In step S4, the formaldehyde low-temperature adsorption aid and activated carbon are mixed by tumbling spraying.

7. A low-temperature, high-efficiency activated carbon composite material for formaldehyde adsorption, characterized in that, The activated carbon composite material for low-temperature and high-efficiency adsorption of formaldehyde, as described in any one of claims 1 to 6, was prepared.

Images