A high specific surface area bamboo-based activated carbon

Abstract

The present invention relates to a high specific surface area bamboo-based activated carbon, belonging to the technical field of activated carbon production. The high specific surface area bamboo-based activated carbon comprises the following raw materials: bamboo powder, an activator, polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer, cetyltrimethylammonium bromide, sodium metaphosphate, and deionized water. The preparation method of the high specific surface area bamboo-based activated carbon comprises the following steps: S1, controlling the heating rate and keeping warm of the bamboo powder under a nitrogen atmosphere to obtain pre-carbonized powder; S2, activating the pre-carbonized powder to obtain an intermediate material; S3, performing post-treatment on the intermediate material to obtain the finished product of the high specific surface area bamboo-based activated carbon. The present invention mainly adds polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer, cetyltrimethylammonium bromide, and sodium metaphosphate to prepare a bamboo-based activated carbon with a high specific surface area.

Description

Technical Field

[0001] The present invention belongs to the technical field of activated carbon production, and specifically relates to a bamboo-based activated carbon with a high specific surface area. Background Art

[0002] Activated carbon is a carbon material with a developed pore structure, having a series of advantages such as good chemical stability, strong adsorption capacity, high mechanical strength, and convenient regeneration. It is widely used in various aspects of industry and life such as military, chemical industry, food, light industry, medicine, pharmacy, and environmental protection. With the development of science and technology and the improvement of people's living standards, the status of activated carbon has become increasingly important, and the demand has also increased year by year. Currently, the main raw materials for producing activated carbon on the market are coal-based and wood-based. Among them, coal is a non-renewable resource, and the trees for producing charcoal grow very slowly, and cutting trees to burn charcoal will cause serious damage to the ecological environment. Therefore, in order to alleviate the contradiction between the demand for charcoal and the protection of ecological resources, people have found a renewable material that can completely replace charcoal, that is, bamboo-based activated carbon fired from bamboo. Compared with trees, bamboo grows much faster. However, the existing bamboo-based activated carbon on the market generally has the problem of low specific surface area and is difficult to meet the requirements of various industries. Therefore, it is particularly important to find a preparation method for bamboo-based activated carbon with a high specific surface area. Summary of the Invention

[0003] The purpose of the present invention is to provide a bamboo-based activated carbon with a high specific surface area, which adds poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer and cetyltrimethylammonium bromide, playing an inducing and regulating role in the pore structure and regular arrangement formed by the activated carbon, thereby increasing the specific surface area of the obtained activated carbon; in addition, the present invention also adds sodium metaphosphate, effectively increasing the active sites of the bamboo-based activated carbon, and further increasing the specific surface area of the bamboo-based activated carbon, solving the problem of low specific surface area of bamboo-based activated carbon existing in the existing bamboo-based activated carbon production technology.

[0004] The purpose of the present invention can be achieved through the following technical solutions:

[0005] A bamboo-based activated carbon with a high specific surface area, the bamboo-based activated carbon with a high specific surface area comprises the following raw materials in parts by weight:

[0006]

[0007] As a preferred scheme of the present invention, the preparation method of the bamboo powder is as follows: The harvested bamboo and Indocalamus tessellatus are decontaminated, and then naturally dried. After drying, they are split, crushed, ground and sieved to obtain a sieved material, and the sieved material is dried under controlled temperature to obtain bamboo powder.

[0008] As a preferred embodiment of the present invention, the natural drying time is 1 - 2 days; the sieving is through a 30 - 50 mesh sieve; the temperature for temperature - controlled drying is 70 - 120 °C, and the drying degree is such that the moisture content of the bamboo powder is less than 15%.

[0009] As a preferred embodiment of the present invention, the activator is an aqueous phosphoric acid solution with a mass concentration of 40 - 60%.

[0010] As a preferred embodiment of the present invention, the method for preparing the high - specific - surface - area bamboo - based activated carbon comprises the following steps:

[0011] S1. Heating the bamboo powder at a controlled rate and holding the temperature in a nitrogen atmosphere to obtain pre - carbonized powder;

[0012] S2. Activating the pre - carbonized powder to obtain an intermediate material;

[0013] S3. Post - treating the intermediate material to obtain the finished product of high - specific - surface - area bamboo - based activated carbon.

[0014] As a preferred embodiment of the present invention, the heating at a controlled rate and holding the temperature in step S1 specifically means: heating at a rate of 5 - 10 °C / min to 500 - 550 °C and holding for 1.5 - 2 h.

[0015] As a preferred embodiment of the present invention, the specific steps of step S2 are: stirring the activator, poly(ethylene oxide) - poly(propylene oxide) - poly(ethylene oxide) triblock copolymer, cetyltrimethylammonium bromide, sodium metaphosphate and deionized water evenly, then adding the pre - carbonized powder and heating at a controlled rate and holding the temperature in a nitrogen atmosphere. After holding, continue heating for activation, and after activation, naturally cool to room temperature to obtain the intermediate material.

[0016] As a preferred embodiment of the present invention, the heating at a controlled rate and holding the temperature specifically means: heating at a heating rate of 10 - 13 °C / min to 200 - 220 °C and holding for 30 - 40 min; the temperature for heating activation is 700 - 850 °C, and the time is 1 - 2 h.

[0017] As a preferred embodiment of the present invention, the post - treatment in step S3 specifically means: stirring the intermediate material in hydrochloric acid, then repeatedly washing with deionized water, and then drying at a controlled temperature to obtain the finished product of high - specific - surface - area bamboo - based activated carbon.

[0018] As a preferred embodiment of the present invention, the concentration of the hydrochloric acid is 5 mol / L; the stirring time is 20 - 50 min; the repeated washing with deionized water is until neutral; the temperature for drying at a controlled temperature is 110 - 120 °C, and the time is 3 - 4 h.

[0019] The beneficial effects of the present invention:

[0020] (1) The present invention adds polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer and hexadecyltrimethylammonium bromide, which play an inducing and regulating role on the pore structure and regular arrangement formed by activated carbon, thereby increasing the specific surface area of the prepared activated carbon. This is because, during the preparation process, as the temperature gradually rises, the interaction between different blocks of the polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer will weaken, causing the polymer chain segments to separate and rearrange, resulting in phase separation, forming tiny, regular micelle structures. These micelles can be carbonized together during the preparation of activated carbon. At the same time, since the triblock copolymer has a regular structure, it helps to precisely adjust the arrangement of the pores. On this basis, hexadecyltrimethylammonium bromide is added. The coordination force between hexadecyltrimethylammonium bromide and other molecules is relatively low. Precisely because of this weak coordination force, hexadecyltrimethylammonium bromide will not destroy the structure of the system raw materials themselves, nor will it change their microscopic morphological characteristics, but it can effectively assist the polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer in inducing and adjusting the pore structure and regular arrangement formed by the activated carbon, thereby increasing the specific surface area of the activated carbon.

[0021] (2) The present invention adds sodium metaphosphate, which effectively increases the active sites of bamboo-based activated carbon, thereby increasing the specific surface area of bamboo-based activated carbon. This is because the phosphate ions in sodium metaphosphate can chemically react with the phenolic hydroxyl groups on the surface of bamboo-based activated carbon to form new bond structures. These newly formed bond structures have high activity, increasing the active sites in the reaction process, providing more adsorption sites and chemical reaction sites, thereby increasing the specific surface area of bamboo-based activated carbon.

[0022] (3) The present invention adopts a phosphoric acid activation process, using phosphoric acid as an activator to enter the interior of the raw material, increase the erosion and penetration ability and occupy more potential positions, which is beneficial to the pore expansion of the activated carbon and increases the product yield. DETAILED DESCRIPTION

[0023] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0024] Example 1

[0025] A bamboo-based activated carbon with a high specific surface area, comprising the following raw materials in parts by weight:

[0026]

[0027] The activator is an aqueous phosphoric acid solution with a mass concentration of 40%.

[0028] The preparation method of the bamboo powder is as follows: Remove impurities from the harvested moso bamboo and indocalamus bamboo, then naturally dry for 1 day. After drying, split, crush, grind it and pass through a 30-mesh sieve to obtain the sieved material. Control the temperature of the sieved material at 95 °C and dry it until the moisture content of the sieved material is 10% to obtain the bamboo powder.

[0029] The preparation method of the high specific surface area bamboo-based activated carbon includes the following steps:

[0030] S1. Heat the bamboo powder in a nitrogen atmosphere at a rate of 5 °C / min to 525 °C and hold for 1.5 h to obtain pre-carbonized powder.

[0031] S2. Stir the activator, polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer, cetyltrimethylammonium bromide, sodium metaphosphate and deionized water evenly, then add the pre-carbonized powder and heat it in a nitrogen atmosphere at a heating rate of 12 °C / min to 200 °C and hold for 40 min. After holding, continue to heat and activate at 700 °C for 1.5 h. After activation, naturally cool to room temperature to obtain the intermediate material.

[0032] S3. Stir the intermediate material in hydrochloric acid with a concentration of 5 mol / L for 20 min, then repeatedly wash it with deionized water until it is neutral, and then control the temperature at 115 °C and dry for 3 h to obtain the finished product of high specific surface area bamboo-based activated carbon.

[0033] Example 2

[0034] A high specific surface area bamboo-based activated carbon, and the high specific surface area bamboo-based activated carbon comprises the following raw materials in parts by weight:

[0035]

[0036] The activator is an aqueous phosphoric acid solution with a mass concentration of 60%.

[0037] [[ID=3I]]The preparation method of the bamboo powder is as follows: Remove impurities from the harvested moso bamboo and indocalamus bamboo, then naturally dry for 2 days. After drying, split, crush, grind it and pass through a 50-mesh sieve to obtain the sieved material. Control the temperature of the sieved material at 120 °C and dry it until the moisture content of the sieved material is 12% to obtain the bamboo powder.

[0038] The preparation method of the high specific surface area bamboo-based activated carbon includes the following steps:

[0039] S1. Heat the bamboo powder in a nitrogen atmosphere at a rate of 10 °C / min to 500 °C and hold for 2 h to obtain pre-carbonized powder.

[0040] S2. Stir the activator, poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer, cetyltrimethylammonium bromide, sodium metaphosphate and deionized water evenly, then add the pre-carbonized powder, and heat it up to 210 °C at a heating rate of 13 °C / min under a nitrogen atmosphere and keep it warm for 30 min. After the heat preservation is completed, continue to heat and activate it at 850 °C for 2 h. After the activation is completed, cool it naturally to room temperature to obtain the intermediate material;

[0041] S3. Stir the intermediate material in hydrochloric acid with a concentration of 5 mol / L for 50 min, then wash it repeatedly with deionized water until it is neutral, and then dry it at a controlled temperature of 110 °C for 3.5 h to obtain the finished product of high specific surface area bamboo-based activated carbon.

[0042] Example 3

[0043] A high specific surface area bamboo-based activated carbon, and the high specific surface area bamboo-based activated carbon comprises raw materials in the following parts by weight:

[0044]

[0045] The activator is an aqueous phosphoric acid solution with a mass concentration of 50%;

[0046] The preparation method of the bamboo material powder is as follows: Remove impurities from the harvested moso bamboo and indocalamus leaves, then naturally dry them for 1 day. After the drying is completed, split, crush, grind and sieve them through a 40-mesh sieve to obtain the sieved material. Control the temperature of the sieved material at 70 °C and dry it until the moisture content of the sieved material is 13% to obtain the bamboo material powder.

[0047] The preparation method of the high specific surface area bamboo-based activated carbon comprises the following steps:

[0048] S1. Heat the bamboo material powder to 550 °C at a rate of 8 °C / min under a nitrogen atmosphere and keep it warm for 1.7 h to obtain the pre-carbonized powder;

[0049] S2. Stir the activator, poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer, cetyltrimethylammonium bromide, sodium metaphosphate and deionized water evenly, then add the pre-carbonized powder, and heat it up to 220 °C at a heating rate of 10 °C / min under a nitrogen atmosphere and keep it warm for 35 min. After the heat preservation is completed, continue to heat and activate it at 775 °C for 1 h. After the activation is completed, cool it naturally to room temperature to obtain the intermediate material;

[0050] S3. Stir the intermediate material in hydrochloric acid with a concentration of 5 mol / L for 35 min, then wash it repeatedly with deionized water until it is neutral, and then dry it at a controlled temperature of 120 °C for 4 h to obtain the finished product of high specific surface area bamboo-based activated carbon.

[0051] Comparative Example 1

[0052] Compared with Example 2, the difference is that in Comparative Example 1, the poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer is not added, and the remaining operation steps and parameters are the same.

[0053] Comparative Example 2

[0054] Compared with Example 2, the difference is that in Comparative Example 2, cetyltrimethylammonium bromide is not added, and the remaining operation steps and parameters are the same.

[0055] Comparative Example 3

[0056] Compared with Example 2, the difference is that in Comparative Example 3, sodium metaphosphate is not added, and the remaining operation steps and parameters are the same.

[0057] Performance detection:

[0058] (1) According to the standard GB / T 7702.21-1997, the specific surface area of the high specific surface area bamboo-based activated carbon products prepared in Examples 1-3 and Comparative Examples 1-3 was tested, and the results are shown in Table 1.

[0059] (2) The yield of the high specific surface area bamboo-based activated carbon products prepared in Examples 1-3 was tested according to the following formula:

[0060] Yield (%) = (m1 / m2) * 100;

[0061] Wherein, m1 is the mass of the high specific surface area bamboo-based activated carbon product, and m2 is the mass of the bamboo powder;

[0062] The results are shown in Table 1.

[0063] Table 1

[0064] <![CDATA[Specific surface area (m 2 / g)]]> Yield (%) Example 1 1683 55.67 Example 2 1905 56.79 Example 3 1692 55.90 Comparative Example 1 1093 —— Comparative Example 2 1031 —— Comparative Example 3 994 ——

[0065] As can be seen from Table 1, the prepared bamboo-based activated carbon product of the present invention has a high specific surface area, and the yield of the prepared bamboo-based activated carbon product under this method is as high as 56.79%. This is because, during the preparation process, as the temperature gradually rises, the interaction between different blocks of the poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer added in the present invention will weaken, causing the polymer segments to separate and rearrange, resulting in a phase separation effect and forming small, regular micelle structures. These micelles can be carbonized together during the preparation of activated carbon. At the same time, due to the regular structure of this triblock copolymer, it helps to precisely adjust the arrangement of pore channels. On this basis, cetyltrimethylammonium bromide is added. The coordination force between cetyltrimethylammonium bromide and other molecules is relatively low. Due to this weak coordination force, cetyltrimethylammonium bromide will not destroy the structure of the system raw materials itself, nor change its microscopic morphological characteristics, but can effectively assist the poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer in inducing and regulating the pore structure and regular arrangement formed by activated carbon, thereby increasing the specific surface area of activated carbon.

[0066] In addition, sodium metaphosphate is added in the present invention, effectively increasing the active sites of the bamboo-based activated carbon and further increasing the specific surface area of the bamboo-based activated carbon. This is because the phosphate ions in sodium metaphosphate can chemically react with the phenolic hydroxyl groups on the surface of the bamboo-based activated carbon to form new bond structures. These newly formed bond structures have high activity, increasing the active sites in the reaction process, providing more adsorption sites and chemical reaction sites, thereby increasing the specific surface area of the bamboo-based activated carbon.

[0067] In the description of the specification, the description with reference to terms such as "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0068] The above content is only an example and illustration of the present invention. Those skilled in the art of the present technology can make various modifications or supplements to the described specific embodiments or use similar methods to replace them. As long as they do not deviate from the invention or exceed the scope defined by the claims of the present invention, they should fall within the protection scope of the present invention.

Claims

1. A bamboo-based activated carbon, characterized in that, The bamboo-based activated carbon comprises raw materials in the following parts by weight: Bamboo powder: 60 parts by weight Activating agent: 18 parts by weight Polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer: 1 part by weight Cetyltrimethylammonium bromide: 0.7 part by weight Sodium metaphosphate: 1 part by weight Deionized water: 113 parts by weight The activating agent is an aqueous phosphoric acid solution with a mass concentration of 60%; The preparation method of the bamboo powder is as follows: Remove impurities from the harvested moso bamboo and indocalamus bamboo, then naturally dry for 2 days. After drying, split, crush, grind and sieve through a 50-mesh sieve to obtain the sieved material. Control the temperature of the sieved material at 120 °C and dry it until the moisture content of the sieved material is 12% to obtain the bamboo powder; The preparation method of the bamboo-based activated carbon comprises the following steps: S1. Heat the bamboo powder in a nitrogen atmosphere at a rate of 10 °C / min to 500 °C and hold for 2 h to obtain pre-carbonized powder; S2. Stir the activating agent, polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer, cetyltrimethylammonium bromide, sodium metaphosphate and deionized water evenly, then add the pre-carbonized powder and heat in a nitrogen atmosphere at a heating rate of 13 °C / min to 210 °C and hold for 30 min. After holding, continue to heat and activate at 850 °C for 2 h. After activation, naturally cool to room temperature to obtain an intermediate material; S3. Stir the intermediate material in hydrochloric acid with a concentration of 5 mol / L for 50 min, then repeatedly wash with deionized water until neutral, and then control the temperature at 110 °C and dry for 3.5 h to obtain the bamboo-based activated carbon.

Images