Bamboo-based activated carbon and a method for preparing the same

Abstract

The present application relates to a kind of bamboo-based activated carbon and its preparation method, belong to activated carbon preparation technical field.The waste bamboo is broken in the present application, then washing and drying, then placed in mixed acid solution is treated under the condition of ultrasonic wave and heating, the bamboo after processing is soaked in the azeotrope of isopropyl alcohol and water, after taking out, washing and drying, high-temperature carbonization, put into the mixed solution containing aluminum sol and silica sol and soak treatment, after drying, activation is carried out, and bamboo-based activated carbon is obtained.The present application uses hydrochloric acid and acetic acid mixture to ultrasonically treat bamboo, synergistically promote the effective dissolution of inorganic salt component in bamboo, reduce the ash content of activated carbon, soak in the azeotrope of isopropyl alcohol and water, promote the effective removal of lignin in bamboo, also further promote the removal of inorganic salt, further reduce the ash content of activated carbon, while increase the mechanical strength of activated carbon, aluminum sol and silica sol soak increase the mechanical strength of activated carbon.

Description

Technical Field

[0001] This invention belongs to the field of activated carbon preparation technology, and relates to a bamboo-based activated carbon and its preparation method. Background Technology

[0002] China boasts the world's richest bamboo resources and the largest bamboo forest area. However, due to limited in-depth development of bamboo products, bamboo use remains largely confined to basic stages such as raw bamboo utilization, weaving handicrafts, and furniture making. Activated carbon, as a high-quality adsorbent, is widely used in environmental protection, chemical, and petroleum fields. Plant resources are renewable organic resources, with reserves ranking first on Earth. They are inexpensive and readily available, making them one of the most promising raw materials for activated carbon production. Bamboo-based activated carbon is also relatively common, but it generally uses raw bamboo as raw material, leading to massive deforestation and even ecological damage. Waste bamboo, as a biological material, possesses characteristics such as high mechanical strength, good flexibility, stable performance, and low density, making it suitable as a raw material for activated carbon production. Furthermore, it enables waste recycling, reducing dependence on bamboo forest resources.

[0003] However, activated carbon made from waste bamboo often has a high ash content, and activated carbon after high-temperature carbonization and activation often has low mechanical strength, resulting in reduced performance. Summary of the Invention

[0004] The purpose of this invention is to provide a bamboo-based activated carbon and its preparation method, belonging to the field of activated carbon preparation technology. This invention involves crushing, washing, and drying waste bamboo, then ultrasonically treating it in a mixed acid solution under ultrasonic and heating conditions. The treated bamboo is then soaked in an azeotropic solution of isopropanol and water, removed, washed, and dried. After high-temperature carbonization, it is soaked in a mixture containing aluminum sol and silica sol, dried, and then activated to obtain bamboo-based activated carbon. This invention uses a mixture of hydrochloric acid and acetic acid for ultrasonic treatment of the bamboo, synergistically promoting the effective dissolution of inorganic salts in the bamboo and reducing the ash content of the activated carbon. Soaking in the azeotropic solution of isopropanol and water promotes the effective release of lignin from the bamboo, further promoting the release of inorganic salts and further reducing the ash content of the activated carbon. The effective release of lignin prevents rapid high-temperature decomposition of lignin during subsequent high-temperature carbonization, which could lead to cracking of the activated carbon, thus improving its mechanical strength. Soaking in aluminum sol and silica sol synergistically increases the mechanical strength of the activated carbon.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A method for preparing bamboo-based activated carbon, the method comprising the following steps:

[0007] (1) The waste bamboo is crushed, washed and dried to obtain bamboo scraps;

[0008] (2) Place bamboo scraps in a mixed acid solution, heat and then ultrasonically treat;

[0009] (3) Soak the ultrasonically treated bamboo scraps in an azeotropic solution of isopropanol and water, then remove them, wash them, and dry them.

[0010] (4) After the dried bamboo scraps are carbonized at high temperature, they are soaked in a mixture containing silica sol and aluminum sol, then dried and activated to obtain bamboo-based activated carbon.

[0011] As a preferred technical solution of the present invention, the particle size of the bamboo scraps in step (1) is 80-120um.

[0012] As a preferred technical solution of the present invention, the mixed acid solution in step (2) is a mixed aqueous solution of hydrochloric acid and acetic acid, wherein the concentration of hydrochloric acid in the mixed aqueous solution is 3-5 mol / L and the concentration of acetic acid is 6-8 mol / L.

[0013] As a preferred technical solution of the present invention, the heating temperature in step (2) is 40-60℃, the ultrasonic frequency is 25-32KHz, and the ultrasonic treatment time is 1-2h.

[0014] As a preferred technical solution of the present invention, the soaking time in step (3) is controlled to be 30-50 min.

[0015] As a preferred technical solution of the present invention, the high-temperature carbonization temperature in step (4) is 450-600℃ and the carbonization time is 50-80min.

[0016] As a preferred embodiment of the present invention, the alumina content in the mixture in step (4) is 6-10 wt%, and the silicon dioxide content is 8-12 wt%.

[0017] As a preferred technical solution of the present invention, the soaking time in step (4) is 2-5 hours.

[0018] As a preferred technical solution of the present invention, the activation temperature in step (4) is 750-900℃, the activation time is 2-4h, and the activator is water vapor.

[0019] The bamboo-based activated carbon prepared by the above method.

[0020] The beneficial effects of this invention are:

[0021] (1) This invention uses waste bamboo as a raw material for preparing activated carbon, which reduces the large-scale logging and destruction of bamboo forest resources, reduces resource waste, and realizes the recycling of waste bamboo, making it green and environmentally friendly.

[0022] (2) In this invention, bamboo scraps are placed in a mixed acid solution containing hydrochloric acid and acetic acid and treated by heating and ultrasound. At a temperature of 40-60℃, hydrochloric acid and acetic acid can synergistically promote the effective dissolution of inorganic salt components in bamboo scraps. At the same time, with the oscillation effect of ultrasound, the removal and dissolution of inorganic salts are further promoted, effectively reducing the ash content of activated carbon.

[0023] (3) In this invention, bamboo scraps are soaked in an azeotropic solution of isopropanol and water. The azeotropic state can improve the permeability of water in the bamboo scraps. Combined with isopropanol, the lignin in the bamboo scraps can be slowly released, preventing the rapid decomposition of lignin at high temperature during the subsequent high-temperature carbonization process, which would cause the activated carbon to crack, and improving the mechanical strength of the activated carbon.

[0024] (4) In this invention, carbonized bamboo is soaked in a mixture containing aluminum sol and silica sol. The nano-silica and nano-alumina in the mixture are adsorbed on the surface of activated carbon. After drying and high-temperature activation, the mechanical strength of activated carbon is effectively improved in a synergistic manner while ensuring the adsorption performance of activated carbon. Detailed Implementation

[0025] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with embodiments, is provided below.

[0026] Example 1

[0027] A method for preparing bamboo-based activated carbon, the method comprising the following steps:

[0028] (1) The waste bamboo is crushed, washed and dried to obtain bamboo fragments with a particle size of 90-100um;

[0029] (2) Place the bamboo scraps in a mixed acid solution, wherein the mixed acid solution is a mixed aqueous solution of hydrochloric acid and acetic acid, wherein the concentration of hydrochloric acid in the mixed aqueous solution is 4 mol / L and the concentration of acetic acid is 7 mol / L, and then heat to 45°C and ultrasonically treat at a frequency of 28 kHz for 1.8 h.

[0030] (3) Soak the ultrasonically treated bamboo scraps in an azeotropic solution of isopropanol and water for 40 minutes, then remove, wash and dry them.

[0031] (4) After drying, the bamboo scraps are carbonized at 500°C for 60 minutes and then soaked in a mixture containing silica sol and aluminum sol for 3 hours. The mixture contains 7 wt% aluminum oxide and 11 wt% silicon dioxide. After drying, the bamboo scraps are activated in steam at 800°C for 2.8 hours to obtain bamboo-based activated carbon.

[0032] The bamboo-based activated carbon prepared by the above method.

[0033] Example 2

[0034] A method for preparing bamboo-based activated carbon, the method comprising the following steps:

[0035] (1) The waste bamboo is crushed, washed and dried to obtain bamboo fragments with a particle size of 80-90um;

[0036] (2) Place the bamboo scraps in a mixed acid solution, wherein the mixed acid solution is a mixed aqueous solution of hydrochloric acid and acetic acid, wherein the concentration of hydrochloric acid in the mixed aqueous solution is 3 mol / L and the concentration of acetic acid is 8 mol / L, and then heat to 50°C and ultrasonically treat at a frequency of 32KHz for 1.2h.

[0037] (3) Soak the ultrasonically treated bamboo scraps in an azeotropic solution of isopropanol and water for 32 minutes, then remove, wash and dry them.

[0038] (4) After the dried bamboo scraps are carbonized at 450°C for 80 minutes, they are soaked in a mixture containing silica sol and aluminum sol for 5 hours. The mixture contains 8 wt% aluminum oxide and 9 wt% silicon dioxide. After drying, the bamboo scraps are activated in steam at 900°C for 2 hours to obtain bamboo-based activated carbon.

[0039] The bamboo-based activated carbon prepared by the above method.

[0040] Example 3

[0041] A method for preparing bamboo-based activated carbon, the method comprising the following steps:

[0042] (1) The waste bamboo is crushed, washed and dried to obtain bamboo fragments with a particle size of 100-110um;

[0043] (2) Place the bamboo scraps in a mixed acid solution, wherein the mixed acid solution is a mixed aqueous solution of hydrochloric acid and acetic acid, wherein the concentration of hydrochloric acid in the mixed aqueous solution is 5 mol / L and the concentration of acetic acid is 6 mol / L, and then heat to 60°C and ultrasonically treat at a frequency of 25 kHz for 2 hours.

[0044] (3) Soak the ultrasonically treated bamboo scraps in an azeotropic solution of isopropanol and water for 40 minutes, then remove, wash and dry them.

[0045] (4) After the dried bamboo scraps are carbonized at 600℃ for 50 minutes, they are soaked in a mixture containing silica sol and aluminum sol for 2.5 hours. The mixture contains 6 wt% aluminum oxide and 12 wt% silicon dioxide. After drying, the bamboo scraps are activated in steam at 750℃ for 4 hours to obtain bamboo-based activated carbon.

[0046] The bamboo-based activated carbon prepared by the above method.

[0047] Example 4

[0048] A method for preparing bamboo-based activated carbon, the method comprising the following steps:

[0049] (1) The waste bamboo is crushed, washed and dried to obtain bamboo fragments with a particle size of 110-120um;

[0050] (2) Place the bamboo scraps in a mixed acid solution, wherein the mixed acid solution is a mixed aqueous solution of hydrochloric acid and acetic acid, wherein the concentration of hydrochloric acid in the mixed aqueous solution is 4.5 mol / L and the concentration of acetic acid is 6.5 mol / L, and heat to 50°C and then sonicate at 30 kHz for 1.5 h.

[0051] (3) Soak the ultrasonically treated bamboo scraps in an azeotropic solution of isopropanol and water for 45 minutes, then remove, wash and dry them.

[0052] (4) After drying, the bamboo scraps are carbonized at 500°C for 60 minutes and then soaked in a mixture containing silica sol and aluminum sol for 4 hours. The mixture contains 9 wt% aluminum oxide and 10 wt% silicon dioxide. After drying, the bamboo scraps are activated in steam at 850°C for 3 hours to obtain bamboo-based activated carbon.

[0053] The bamboo-based activated carbon prepared by the above method.

[0054] Comparative Example 1

[0055] A method for preparing bamboo-based activated carbon, the method comprising the following steps:

[0056] (1) The waste bamboo is crushed, washed and dried to obtain bamboo fragments with a particle size of 110-120um;

[0057] (2) Place the bamboo scraps in a hydrochloric acid aqueous solution with a concentration of 4.5 mol / L, heat to 50°C, and then sonicate at a frequency of 30 kHz for 1.5 h.

[0058] (3) Soak the ultrasonically treated bamboo scraps in an azeotropic solution of isopropanol and water for 45 minutes, then remove, wash and dry them.

[0059] (4) After drying, the bamboo scraps are carbonized at 500°C for 60 minutes and then soaked in a mixture containing silica sol and aluminum sol for 4 hours. The mixture contains 9 wt% aluminum oxide and 10 wt% silicon dioxide. After drying, the bamboo scraps are activated in steam at 850°C for 3 hours to obtain bamboo-based activated carbon.

[0060] The bamboo-based activated carbon prepared by the above method.

[0061] Comparative Example 2

[0062] A method for preparing bamboo-based activated carbon, the method comprising the following steps:

[0063] (1) The waste bamboo is crushed, washed and dried to obtain bamboo fragments with a particle size of 110-120um;

[0064] (2) Place the bamboo scraps in an acetic acid aqueous solution with a concentration of 6.5 mol / L, heat to 50°C, and then sonicate at a frequency of 30 kHz for 1.5 h.

[0065] (3) Soak the ultrasonically treated bamboo scraps in an azeotropic solution of isopropanol and water for 45 minutes, then remove, wash and dry them.

[0066] (4) After drying, the bamboo scraps are carbonized at 500°C for 60 minutes and then soaked in a mixture containing silica sol and aluminum sol for 4 hours. The mixture contains 9 wt% aluminum oxide and 10 wt% silicon dioxide. After drying, the bamboo scraps are activated in steam at 850°C for 3 hours to obtain bamboo-based activated carbon.

[0067] The bamboo-based activated carbon prepared by the above method.

[0068] Comparative Example 3

[0069] A method for preparing bamboo-based activated carbon, the method comprising the following steps:

[0070] (1) The waste bamboo is crushed, washed and dried to obtain bamboo fragments with a particle size of 110-120um;

[0071] (2) Place the bamboo scraps in a mixed acid solution, wherein the mixed acid solution is a mixed aqueous solution of hydrochloric acid and acetic acid, wherein the concentration of hydrochloric acid in the mixed aqueous solution is 4.5 mol / L and the concentration of acetic acid is 6.5 mol / L, and soak for 1.5 hours after heating to 50°C;

[0072] (3) Soak the ultrasonically treated bamboo scraps in an azeotropic solution of isopropanol and water for 45 minutes, then remove, wash and dry them.

[0073] (4) After drying, the bamboo scraps are carbonized at 500°C for 60 minutes and then soaked in a mixture containing silica sol and aluminum sol for 4 hours. The mixture contains 9 wt% aluminum oxide and 10 wt% silicon dioxide. After drying, the bamboo scraps are activated in steam at 850°C for 3 hours to obtain bamboo-based activated carbon.

[0074] The bamboo-based activated carbon prepared by the above method.

[0075] Comparative Example 4

[0076] A method for preparing bamboo-based activated carbon, the method comprising the following steps:

[0077] (1) The waste bamboo is crushed, washed and dried to obtain bamboo fragments with a particle size of 110-120um;

[0078] (2) Place the bamboo scraps in a mixed acid solution, wherein the mixed acid solution is a mixed aqueous solution of hydrochloric acid and acetic acid, wherein the concentration of hydrochloric acid in the mixed aqueous solution is 2 mol / L and the concentration of acetic acid is 9 mol / L, and then heat to 50°C and ultrasonically treat at a frequency of 30 kHz for 1.5 h.

[0079] (3) Soak the ultrasonically treated bamboo scraps in an azeotropic solution of isopropanol and water for 45 minutes, then remove, wash and dry them.

[0080] (4) After drying, the bamboo scraps are carbonized at 500°C for 60 minutes and then soaked in a mixture containing silica sol and aluminum sol for 4 hours. The mixture contains 9 wt% aluminum oxide and 10 wt% silicon dioxide. After drying, the bamboo scraps are activated in steam at 850°C for 3 hours to obtain bamboo-based activated carbon.

[0081] The bamboo-based activated carbon prepared by the above method.

[0082] Comparative Example 5

[0083] A method for preparing bamboo-based activated carbon, the method comprising the following steps:

[0084] (1) The waste bamboo is crushed, washed and dried to obtain bamboo fragments with a particle size of 110-120um;

[0085] (2) Place the bamboo scraps in a mixed acid solution, wherein the mixed acid solution is a mixed aqueous solution of hydrochloric acid and acetic acid, wherein the concentration of hydrochloric acid in the mixed aqueous solution is 6 mol / L and the concentration of acetic acid is 5 mol / L, and then heat to 50°C and ultrasonically treat at a frequency of 30 kHz for 1.5 h.

[0086] (3) Soak the ultrasonically treated bamboo scraps in an azeotropic solution of isopropanol and water for 45 minutes, then remove, wash and dry them.

[0087] (4) After drying, the bamboo scraps are carbonized at 500°C for 60 minutes and then soaked in a mixture containing silica sol and aluminum sol for 4 hours. The mixture contains 9 wt% aluminum oxide and 10 wt% silicon dioxide. After drying, the bamboo scraps are activated in steam at 850°C for 3 hours to obtain bamboo-based activated carbon.

[0088] The bamboo-based activated carbon prepared by the above method.

[0089] Comparative Example 6

[0090] A method for preparing bamboo-based activated carbon, the method comprising the following steps:

[0091] (1) The waste bamboo is crushed, washed and dried to obtain bamboo fragments with a particle size of 110-120um;

[0092] (2) Place the bamboo scraps in a mixed acid solution, wherein the mixed acid solution is a mixed aqueous solution of hydrochloric acid and acetic acid, wherein the concentration of hydrochloric acid in the mixed aqueous solution is 4.5 mol / L and the concentration of acetic acid is 6.5 mol / L, and heat to 50°C and then sonicate at 30 kHz for 1.5 h.

[0093] (3) Soak the ultrasonically treated bamboo scraps in boiling water for 45 minutes, then take them out, wash and dry them.

[0094] (4) After drying, the bamboo scraps are carbonized at 500°C for 60 minutes and then soaked in a mixture containing silica sol and aluminum sol for 4 hours. The mixture contains 9 wt% aluminum oxide and 10 wt% silicon dioxide. After drying, the bamboo scraps are activated in steam at 850°C for 3 hours to obtain bamboo-based activated carbon.

[0095] Comparative Example 7

[0096] A method for preparing bamboo-based activated carbon, the method comprising the following steps:

[0097] (1) The waste bamboo is crushed, washed and dried to obtain bamboo fragments with a particle size of 110-120um;

[0098] (2) Place the bamboo scraps in a mixed acid solution, wherein the mixed acid solution is a mixed aqueous solution of hydrochloric acid and acetic acid, wherein the concentration of hydrochloric acid in the mixed aqueous solution is 4.5 mol / L and the concentration of acetic acid is 6.5 mol / L, and heat to 50°C and then sonicate at 30 kHz for 1.5 h.

[0099] (3) Soak the ultrasonically treated bamboo scraps in an azeotropic solution of isopropanol and water for 45 minutes, then remove, wash and dry them.

[0100] (4) After drying, the bamboo scraps are carbonized at 500°C for 60 minutes, then soaked in silica sol for 4 hours. The silica sol contains 19 wt% silica. After drying, the bamboo scraps are activated in steam at 850°C for 3 hours to obtain bamboo-based activated carbon.

[0101] The bamboo-based activated carbon prepared by the above method.

[0102] Comparative Example 8

[0103] A method for preparing bamboo-based activated carbon, the method comprising the following steps:

[0104] (1) The waste bamboo is crushed, washed and dried to obtain bamboo fragments with a particle size of 110-120um;

[0105] (2) Place the bamboo scraps in a mixed acid solution, wherein the mixed acid solution is a mixed aqueous solution of hydrochloric acid and acetic acid, wherein the concentration of hydrochloric acid in the mixed aqueous solution is 4.5 mol / L and the concentration of acetic acid is 6.5 mol / L, and heat to 50°C and then sonicate at 30 kHz for 1.5 h.

[0106] (3) Soak the ultrasonically treated bamboo scraps in an azeotropic solution of isopropanol and water for 45 minutes, then remove, wash and dry them.

[0107] (4) After drying, the bamboo scraps are carbonized at 500°C for 60 minutes, then soaked in aluminum sol for 4 hours. The aluminum sol contains 19 wt% aluminum oxide. After drying, the bamboo scraps are activated in steam at 850°C for 3 hours to obtain bamboo-based activated carbon.

[0108] The bamboo-based activated carbon prepared by the above method.

[0109] Performance testing

[0110] The bamboo-based activated carbon prepared in Examples 1-4 and Comparative Examples 1-8 was tested for iodine value according to GB / T14296.8-2015, ash content according to GB / T12496.3-1999, and strength according to GB / T14296.6-1999. The test results are shown in Table 1 below.

[0111] Table 1

[0112]

[0113]

[0114] The test results above show that, in Comparative Example 1, which was treated with only hydrochloric acid aqueous solution and then ultrasonically, the ash content of the activated carbon increased significantly. In Comparative Example 2, which was treated with only acetic acid aqueous solution and then ultrasonically, the ash content of the activated carbon increased significantly. In Comparative Example 3, which was not treated with ultrasound, the ash content of the activated carbon increased significantly. In Comparative Example 4, which was treated with a decrease in hydrochloric acid concentration and an increase in acetic acid concentration, the ash content of the activated carbon increased significantly. In Comparative Example 5, which was treated with a decrease in hydrochloric acid concentration and an increase in acetic acid concentration, the ash content of the activated carbon increased significantly. In Comparative Example 6, which was treated with bamboo fragments soaked in boiling water, the mechanical strength of the activated carbon decreased significantly and the ash content increased. In Comparative Example 7, which was treated with carbonized bamboo in silica sol, the mechanical strength of the activated carbon decreased significantly and the iodine value decreased. In Comparative Example 8, which was treated with carbonized bamboo in aluminum sol, the mechanical strength decreased significantly and the iodine value decreased.

[0115] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for preparing bamboo-based activated carbon, characterized in that, The preparation method includes the following steps: (1) The waste bamboo is crushed, washed and dried to obtain bamboo scraps; (2) Place bamboo scraps in a mixed acid solution, heat and then ultrasonically treat; (3) Soak the ultrasonically treated bamboo scraps in an azeotropic solution of isopropanol and water, then remove them, wash them, and dry them. (4) After the dried bamboo scraps are carbonized at high temperature, they are soaked in a mixture containing silica sol and aluminum sol, then dried and activated to obtain bamboo-based activated carbon. Wherein, the mixed acid solution in step (2) is a mixed aqueous solution of hydrochloric acid and acetic acid, wherein the concentration of hydrochloric acid in the mixed aqueous solution is 3-5 mol / L and the concentration of acetic acid is 6-8 mol / L; The alumina content in the mixture in step (4) is 6-10 wt%, and the silica content is 8-12 wt%.

2. The method for preparing bamboo-based activated carbon according to claim 1, characterized in that, The particle size of the bamboo scraps mentioned in step (1) is 80-120μm.

3. The method for preparing bamboo-based activated carbon according to claim 1, characterized in that, The heating temperature in step (2) is 40-60℃, the ultrasonic frequency is 25-32KHz, and the ultrasonic treatment time is 1-2h.

4. The method for preparing bamboo-based activated carbon according to claim 1, characterized in that, The soaking time in step (3) is controlled to be 30-50 minutes.

5. The method for preparing bamboo-based activated carbon according to claim 1, characterized in that, The high-temperature carbonization temperature in step (4) is 450-600℃, and the carbonization time is 50-80min.

6. The method for preparing bamboo-based activated carbon according to claim 1, characterized in that, The soaking time in step (4) is 2-5 hours.

7. The method for preparing bamboo-based activated carbon according to claim 1, characterized in that, The activation temperature in step (4) is 750-900℃, the activation time is 2-4h, and the activator is water vapor.

8. A bamboo-based activated carbon prepared by the preparation method according to any one of claims 1-7.

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