Porous activated carbon prepared from balsa wood material as well as preparation method and application of porous activated carbon

Abstract

The invention discloses porous activated carbon prepared from a balsa wood material and a preparation method and application of the porous activated carbon, the pore diameter of the porous activated carbon ranges from 0.4 nm to 400 nm, the pore volume ratio of micropores with the pore diameter being 0.4 nm to 2 nm, mesopores with the pore diameter being 2 nm to 50 nm and macropores with the pore diameter being 50 nm to 400 nm is larger than 30%, and the specific surface area of the porous activated carbon is 500 m / g to 700 m / g; the carbon tetrachloride adsorption rate is 130%-145%, and the adsorbent has excellent adsorption performance.

Description

Technical Field

[0001] The invention belongs to the technical field of adsorption materials, and specifically relates to a porous activated carbon prepared by using balsa wood material, and a preparation method and application thereof. Background Art

[0002] Carbon tetrachloride is a common chlorinated volatile organic compound, which is often used as a solvent in the fields of industry, agriculture, and pharmaceutical production. Carbon tetrachloride volatilized in the ambient air can enter the human body through inhalation or skin absorption, causing damage to the liver, kidneys, and nervous system, and even cancer. Carbon tetrachloride is also ecotoxic and difficult to degrade, causing long-term damage to water bodies and soil. Therefore, the removal and recovery of carbon tetrachloride gas volatilized in the environment and carbon tetrachloride in industrial production waste have become important issues in environmental governance.

[0003] In the carbon tetrachloride removal and recovery process, the most widely used and most convenient technical solution is the activated carbon adsorption recovery method. The adsorption capacity of activated carbon materials for carbon tetrachloride molecules can also reflect its adsorption performance for other chlorinated volatile organic molecules. However, the current process scheme for increasing the specific surface area of ​​the material is complicated and involves the use of a large amount of corrosive strong acid and strong alkali reagents. And the current technical process has room for further improvement in the adsorption capacity of carbon tetrachloride. Therefore, the development of activated carbon materials with simple processes and high carbon tetrachloride adsorption rates is still a difficulty in the prior art. Summary of the invention

[0004] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a method for preparing activated carbon with multi-level pores using balsa wood material. The prepared activated carbon material can achieve efficient adsorption of carbon tetrachloride and has excellent adsorption performance.

[0005] The purpose of the present invention is achieved through the following technical solutions.

[0006] A porous activated carbon prepared from balsa wood material, wherein the pore diameter of the porous activated carbon is 0.4 nm to 400 nm.

[0007] The pore volume of the porous activated carbon with pore diameters of 0.4 nm to 2 nm micropores, 2 nm to 50 nm mesopores and 50 nm to 400 nm macropores is greater than 30%.

[0008] The specific surface area of ​​the porous activated carbon is 500-700 m² / g.

[0009] A method for preparing porous activated carbon by using balsa wood material, using sodium cyclohexanesulfamic acid as a pore-forming agent.

[0010] A method for preparing porous activated carbon using balsa wood material, the preparation method specifically comprising the following steps: S1. Preprocessing The balsa wood is cut into blocks, preheated at 220°C to 260°C, cooled, crushed, and sieved to obtain preheated balsa wood powder; S2. Mixing and pyrolysis Preheat-treated balsa wood powder A, sodium cyclohexanesulfamate and water are mixed in a weight ratio of 1:(0.2-0.6):(3-6), stirred, dried, heated to 750°C-800°C in an inert atmosphere, and cooled to obtain a primary carbonized material.

[0011] S3. Chemical activation and post-treatment The primary carbonized material is soaked in a sodium hydroxide solution, stirred, filtered, washed with water until neutral, then soaked in a hydrochloric acid solution, filtered, washed with water until neutral, and dried to obtain a porous activated carbon material.

[0012] In step S2, the inert gas is one of nitrogen or argon.

[0013] In step S2, the heating rate is 2°C to 5°C per minute.

[0014] In step S3, the concentration of the hydrochloric acid solution used for soaking the carbon material is 0.1 mol / L ~ 1 mol / L.

[0015] The porous activated carbon or the porous activated carbon prepared by the above preparation method is applied to carbon tetrachloride adsorption.

[0016] The porous activated carbon has an adsorption rate of 130% to 145% for carbon tetrachloride.

[0017] Compared with the prior art, the present invention has the following beneficial effects: The activated carbon material prepared by the present invention has an adsorption capacity of more than 130% for carbon tetrachloride when the specific surface area is not more than 700 m2 / g.

[0018] The activated carbon material prepared by the present invention has a multi-level pore structure, and the prepared activated carbon material contains abundant micropores, mesopores and macropores, and the micropore volume ratio, mesopore volume ratio and macropore volume ratio are not less than 30%. The multi-level pore structure combined with the multi-scale pore structure can greatly improve the adsorption effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The scanning electron microscope characterization image (a) and elemental energy spectrum analysis data (b) of the carbon material obtained in Example 1; Figure 2This is a graph showing the change in specific surface area and pore volume increase of the carbon material obtained in Example 1 with the pore size.

[0020] Figure 3 Carbon tetrachloride adsorption rate data of the carbon material obtained in Example 1.

[0021] Figure 4 The scanning electron microscope characterization image (a) and elemental energy spectrum analysis data (b) of the carbon material obtained in Example 2; Figure 5 This is a graph showing the change in specific surface area and pore volume increase of the carbon material obtained in Example 2 as a function of pore size.

[0022] Figure 6 Carbon tetrachloride adsorption rate data of the carbon material obtained in Example 2.

[0023] Figure 7 The scanning electron microscope characterization image (a) and elemental energy spectrum analysis data (b) of the carbon material obtained in Example 3; Figure 8 This is a graph showing the change in specific surface area and pore volume increase of the carbon material obtained in Example 3 as a function of pore size.

[0024] Fig. 9 Carbon tetrachloride adsorption rate data of the carbon material obtained in Example 3. DETAILED DESCRIPTION

[0025] The technical solution of the present invention is further described below in conjunction with specific embodiments.

[0026] The drugs involved in the following embodiments are as follows: Sodium cyclamate: 99%, Shanghai MacLean Biochemical Technology Co., Ltd. Hydrochloric acid: mass percentage 35~38%, Tianjin Fengchuan Chemical Reagent Technology Co., Ltd. Sodium hydroxide: mass percentage ꞷ >96%, Tianjin Hengxing Chemical Reagent Manufacturing Co., Ltd. Example

[0027] A method for preparing porous carbon using balsa wood material comprises the following steps: 1) Cut 2.5-year-old balsa wood from Indonesia into blocks with a length, width and height of about 2 cm each, and then place the blocks of balsa wood in an oven at 240 o After the preheating is completed, the oven is cooled to 60°C. o C, the preheated balsa wood material is put into a grinder for crushing, and sieved with a 40-mesh screen to obtain preheated balsa wood powder A.

[0028] 2) Add the preheated balsa wood powder A and sodium cyclohexanesulfamate to water and mechanically stir and mix for 3 hours. The weight ratio of the preheated balsa wood powder A, sodium cyclohexanesulfamate and water is 1: (0.5): 4. The stirred and mixed materials are placed at 80 o C oven to obtain mixed raw material B. Mixed raw material B was placed in an argon atmosphere protection heating furnace at 3 per minute. o The heating rate was heated to 800 o C, heat treated for 2 hours. After the heat treatment, cooled to room temperature, primary carbonized material C was obtained.

[0029] 3) Soak the obtained primary carbonized material C in 1 mol / L sodium hydroxide solution and stir for 24 hours, then filter it, and wash the filtered carbon material with deionized water until the washing liquid is neutral. Then, soak the washed carbon material in 0.5 mol / L hydrochloric acid solution and stir for 24 hours, then filter it. Wash the powder material after filtering out the liquid with deionized water until the pH value of the washing liquid is neutral. Finally, heat the obtained powder material at 90 o C is dried in a forced air drying oven to obtain a multi-level porous activated carbon material.

[0030] The surface morphology of the obtained material was characterized by a scanning electron microscope, and the elemental composition of the obtained material was analyzed by an energy spectrum analyzer. Figure 1 As shown in the figure, the apparent morphology of the obtained material is granular, and the surface has a micron-scale pore structure; the main component of the obtained material is carbon (symbol: C), with a mass percentage of 93.37%. The other components contain oxygen (O), sulfur (S), nitrogen (N), and sodium (Na), which may be related to the pore-forming agent sodium cyclohexanesulfamic acid. The surface area and pore size distribution of the obtained carbon material were tested using a specific surface area and pore size analyzer, and the results are shown in the figure below. Figure 2 As shown. Figure 2 It can be seen that the specific surface area of ​​the obtained carbon material is 522.69 cm 2 / g; the pore size of the obtained carbon material is in the range of 0.6 nm ~ 400 nm; in the pore size range of 0.4 nm ~ 400 nm, the micropore volume accounts for 35.64%; the mesopore volume accounts for 32.49%; and the macropore volume accounts for 31.87%. The obtained activated carbon material with a multi-level pore structure was subjected to a carbon tetrachloride adsorption test, and the results are as follows Figure 3 As shown, the carbon tetrachloride adsorption rate of the obtained porous activated carbon material is 138.2%. Example

[0031] A method for preparing porous carbon using balsa wood material comprises the following steps: 1) Cut 3-year-old balsa wood from Papua New Guinea into blocks with a length, width and height of about 2 cm each, and then place the blocks of balsa wood in an oven at 260 o After the preheating is completed, the oven is cooled to 60°C. o C, the preheated balsa wood material is put into a grinder for crushing, and sieved with a 40-mesh screen to obtain preheated balsa wood powder A.

[0032] 2) Add the preheated balsa wood powder A and sodium cyclohexanesulfamate to water and mechanically stir and mix for 6 hours. The weight ratio of the preheated balsa wood powder A, sodium cyclohexanesulfamate and water is 1: 1: 6. The stirred and mixed materials are placed at 80 o C oven to obtain mixed raw material B. Mixed raw material B was placed in a nitrogen atmosphere protection heating furnace at 2 per minute. o The heating rate was heated to 850 o C, heat treated for 4 hours. After the heat treatment, cooled to room temperature, primary carbonized material C was obtained.

[0033] 3) The obtained primary carbonized material C was soaked and stirred in 2 mol / L sodium hydroxide solution for 12 hours, then filtered, and the filtered carbon material was washed with deionized water until the washing liquid was neutral. Then, the washed carbon material was soaked and stirred in 0.1 mol / L hydrochloric acid solution for 48 hours, then filtered. The powder material after filtering out the liquid was washed with deionized water until the pH value of the washing liquid was neutral. Finally, the obtained powder material was heated to 110 °C. o C is dried in a forced air drying oven to obtain a multi-level porous activated carbon material.

[0034] The surface morphology of the obtained material was characterized by a scanning electron microscope, and the elemental composition of the obtained material was analyzed by an energy spectrum analyzer. Figure 4 As shown, the apparent morphology of the obtained material is granular, with a micrometer-scale pore structure on the surface, and the pore structure of the wood material can be seen; the main component of the obtained material is carbon (symbol: C), with a mass percentage of >90%. The oxygen (O), sulfur (S), nitrogen (N), and sodium (Na) contained in other components may be related to the pore-forming agent sodium cyclohexanesulfamic acid. The surface area and pore size distribution of the obtained carbon material were tested using a specific surface area and pore size analyzer, and the results are shown in Figure 5 As shown. Figure 5 It can be seen that the specific surface area of ​​the obtained carbon material is 674.86 cm 2 / g, the pore size of the obtained carbon material is in the range of 0.6nm ~ 400nm; in the pore size range of 0.4nm~400nm, the micropore volume accounts for 34.76%; the mesopore volume accounts for 34.34%; and the macropore volume accounts for 30.90%. The obtained carbon material with multi-level pore structure was subjected to carbon tetrachloride adsorption test, and the results are as follows Figure 6 As shown, the carbon tetrachloride adsorption rate of the material is 144.5%. Example

[0035] A method for preparing porous carbon using balsa wood material comprises the following steps: 1) Cut the 2-year-old balsa wood from Indonesia into blocks with a length, width and height of about 2 cm each, and then place the blocks of balsa wood in an oven at 220 o After the preheating is completed, the oven is cooled to 60°C. o C, the preheated balsa wood material is put into a grinder for crushing, and sieved with a 40-mesh screen to obtain preheated balsa wood powder A.

[0036] 2) Add the preheated balsa wood powder A and sodium cyclohexanesulfamate to water and mechanically stir and mix for 6 hours. The weight ratio of the preheated balsa wood powder A, sodium cyclohexanesulfamate and water is 1: 0.3: 3. The stirred and mixed materials are placed at 80 o C oven to obtain mixed raw material B. Mixed raw material B was placed in a nitrogen atmosphere protection heating furnace at 5 per minute. o The heating rate was heated to 750 o C, heat treatment for 1 hour. After the heat treatment, cool to room temperature to obtain primary carbonized material C.

[0037] 3) The obtained primary carbonized material C was soaked and stirred in 0.5 mol / L sodium hydroxide solution for 48 hours, then filtered, and the filtered carbon material was washed with deionized water until the washing liquid was neutral. Then, the washed carbon material was soaked and stirred in 1 mol / L hydrochloric acid solution for 12 hours, then filtered. The powder material after filtering out the liquid was washed with deionized water until the pH value of the washing liquid was neutral. Finally, the obtained powder material was heated to 60 °C. o C is dried in a forced air drying oven to obtain a multi-level porous activated carbon material.

[0038] The surface morphology of the obtained material was characterized by a scanning electron microscope, and the elemental composition of the obtained material was analyzed by an energy spectrum analyzer. Figure 7As shown, the apparent morphology of the obtained material is granular, and the surface has a micron-scale pore structure; the main component of the obtained material is carbon (symbol: C), with a mass percentage of >90%. The oxygen (O), sulfur (S), nitrogen (N), and sodium (Na) contained in other components may be related to the pore-forming agent sodium cyclohexanesulfamic acid. The surface area and pore size distribution of the obtained carbon material were tested using a specific surface area and pore size analyzer, and the results are shown in Figure 8 As shown. Figure 8 It can be seen that the specific surface area of ​​the obtained carbon material is 501.48 cm 2 / g, the pore size of the obtained carbon material is in the range of 0.6 nm ~ 400 nm; in the pore size range of 0.4 nm ~ 400 nm, the micropore volume accounts for 36.72%; the mesopore volume accounts for 33.02%; and the macropore volume accounts for 30.26%. The obtained carbon material with a multi-level pore structure was subjected to a carbon tetrachloride adsorption test, and the results are as follows Fig. 9 As shown, the carbon tetrachloride adsorption rate of the material is 133.7%.

Claims

1. A porous activated carbon prepared from balsa wood material, characterized in that: The pore diameter of the porous activated carbon is 0.4 nm to 400 nm.

2. The porous activated carbon according to claim 1, characterized in that The porous activated carbon has pore volumes of micropores with pore sizes of 0.4 nm to 2 nm, mesopores with pore sizes of 2 nm to 50 nm, and macropores with pore sizes of 50 nm to 400 nm, all of which account for more than 30%.

3. The porous activated carbon according to claim 1 or 2, characterized in that: The specific surface area of ​​the porous activated carbon is 500-700 m² / g.

4. A method for preparing porous activated carbon using balsa wood material, characterized in that: Sodium cyclohexanesulfamic acid is used as a pore-forming agent in the preparation process.

5. A method for preparing porous activated carbon using balsa wood material, characterized in that: The preparation method specifically comprises the following steps: S1. Preprocessing The balsa wood is cut into blocks, preheated at 220°C to 260°C, cooled, crushed, and sieved to obtain preheated balsa wood powder; S2. Mixing and pyrolysis The preheated balsa wood powder A, sodium cyclohexanesulfamate and water are mixed in a weight ratio of 1:(0.2-0.6):(3-6), stirred, dried, heated to 750°C-800°C in an inert atmosphere, and cooled to obtain a primary carbonized material; S3. Chemical activation and post-treatment The primary carbonized material is soaked in a sodium hydroxide solution, stirred, filtered, washed with water until neutral, then soaked in a hydrochloric acid solution, filtered, washed with water until neutral, and dried to obtain a porous activated carbon material.

6. The method for preparing porous activated carbon using balsa wood material according to claim 5, characterized in that: In step S2, the inert gas is one of nitrogen or argon.

7. The method for preparing porous activated carbon using balsa wood material according to claim 5, characterized in that: In step S2, the heating rate is 2°C to 5°C per minute.

8. The method for preparing porous activated carbon using balsa wood material according to claim 5, characterized in that: In step S3, the concentration of the hydrochloric acid solution used for soaking the carbon material is 0.1 mol / L ~ 1 mol / L.

9. The porous activated carbon or the porous activated carbon prepared by the above preparation method is applied to carbon tetrachloride adsorption.

10. The use according to claim 9, characterized in that: The porous activated carbon has an adsorption rate of 130% to 145% for carbon tetrachloride.

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