Activated carbon prepared from glucose as well as preparation method and application of activated carbon

Abstract

The invention relates to activated carbon prepared from glucose as well as a preparation method and application thereof. The preparation method comprises the following steps: S1, mixing glucose and aluminum salt, and performing hydrothermal reaction to obtain a glucose-aluminum hydroxide precursor; s2, heating and roasting the glucose-aluminum hydroxide precursor obtained in the step S1 in an oxygen-free environment to obtain an activated carbon-aluminum oxide compound; and S3, acidifying the activated carbon-aluminum oxide compound obtained in the step S2 to obtain the activated carbon. Compared with the prior art, the one-step activation method taking the glucose as the precursor can remarkably reduce the preparation cost, and meanwhile, the pore structure and the adsorption performance of the activated carbon are improved. The glucose is converted into a valuable activated carbon product, so that the economic benefit is improved, and effective utilization of resources is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of activated carbon processing, and particularly relates to an activated carbon prepared from glucose, a preparation method thereof, and an application thereof. Background Art

[0002] Activated carbon is mainly made from carbon-containing raw materials such as coal, wood, and fruit shells through processes such as carbonization and activation. The characteristics of activated carbon lie in its developed pore structure, large specific surface area, and abundant surface chemical groups, which endow it with strong adsorption performance. Activated carbon has broad application prospects and unique advantages in the fields of adsorption, electrode materials, catalysts, etc.

[0003] Glucose (chemical formula C6H 12 O6) is an organic compound and is the most widely distributed and important monosaccharide in nature. Glucose is derived from the photosynthesis of plants, is a renewable resource, and has the advantages of environmental protection and sustainability. Pure glucose is a colorless crystal, has a sweet taste but is less sweet than sucrose, is easily soluble in water, slightly soluble in ethanol, and insoluble in ether. It is easily decomposed when heated under alkaline conditions. Glucose has active chemical properties and can be converted into various products through a series of reactions such as hydrogenation, oxidation, and isomerization to meet the needs of different fields.

[0004] Patent CN107746056A discloses a production method of spherical activated carbon, which includes the following steps: (1) Mix glucose, an anionic surfactant, a cationic surfactant, humic acid, and water, carry out a hydrothermal reaction, and filter to obtain hydrothermal carbon spheres; (2) Carbonize the hydrothermal carbon spheres obtained in step (1) under nitrogen protection to obtain carbonized carbon spheres; (3) Mix the carbonized carbon spheres obtained in step (2) with an activator and carry out activation under nitrogen protection to obtain spherical activated carbon. Among them, the anionic surfactant is rhamnolipid, and the cationic surfactant is cetyltrimethylammonium bromide. Although these two surfactants bring some unique advantages in the preparation of activated carbon, there are also some potential disadvantages. For example, the cost of rhamnolipid is relatively high, its solubility is limited, and additional cosolvents or pretreatment steps are required to improve its dispersibility during the preparation process. In addition, it is also affected by pH value and ionic strength, etc. Cetyltrimethylammonium bromide has certain toxicity, and there may be residues during the preparation process, which pose potential risks to the environment and the safety of operators, and has poor biodegradability, etc.

[0005] Glucose has good biocompatibility in the human body and can be quickly absorbed and utilized by the human body. Therefore, it is hoped to develop a new process to convert glucose into activated carbon in view of the biocompatibility and renewable nature of glucose. Summary of the Invention

[0006] The object of the present invention is to provide an activated carbon prepared from glucose, a preparation method thereof and an application thereof, so as to overcome the potential problems caused by surfactants in the prior art.

[0007] The object of the present invention can be achieved by the following technical solutions:

[0008] One of the technical solutions of the present invention is to provide a method for preparing activated carbon from glucose, comprising the following steps:

[0009] S1. Mix glucose and an aluminum salt, and obtain a glucose-aluminum hydroxide precursor after hydrothermal reaction;

[0010] S2. Heat the glucose-aluminum hydroxide precursor obtained in step S1 in an anaerobic environment to obtain an activated carbon-aluminum oxide composite;

[0011] S3. Acidify the activated carbon-aluminum oxide composite obtained in step S2 to obtain activated carbon.

[0012] In some specific embodiments, in step S1, the molar ratio of the aluminum salt to glucose is 1:(0.8 - 6.4).

[0013] More preferably, the molar ratio of the aluminum salt to glucose is 1:(1.6 - 5.2).

[0014] In some specific embodiments, in step S1, the aluminum salt is selected from any one of aluminum nitrate and aluminum nitrate nonahydrate.

[0015] In some specific embodiments, in step S1, the temperature of the hydrothermal reaction is 100 - 200 °C, and the time of the hydrothermal reaction is 10 - 20 h.

[0016] More preferably, the temperature of the hydrothermal reaction is 140 - 180 °C, and the time of the hydrothermal reaction is 20 h.

[0017] In some specific embodiments, in step S2, the temperature of the roasting is 500 - 550 °C, and the time of the roasting is 2 - 5 h.

[0018] More preferably, the temperature of the roasting is 550 °C, and the time of the roasting is 4 h.

[0019] In some specific embodiments, in step S2, the protective gas for the anaerobic environment is nitrogen and / or argon.

[0020] More preferably, the protective gas for the anaerobic environment is nitrogen.

[0021] In some specific embodiments, in step S3, the concentration of the acidification treatment is 5% - 15%, and the time of the acidification treatment is 5 - 12 h.

[0022] More preferably, the concentration of acidification is 10%, and the acidification treatment time is 10 h.

[0023] In some specific embodiments, in step S3, the solution used for acidification is hydrochloric acid.

[0024] In the present invention, glucose is used as the raw material for manufacturing activated carbon. After hydrothermal treatment with an aluminum salt such as aluminum nitrate nonahydrate, a glucose-aluminum hydroxide precursor is obtained. Then, under oxygen isolation, the precursor is calcined with a heating rate of 10 °C / min to obtain an activated carbon-aluminum oxide composite. After the product is acidified, such as treated with hydrochloric acid, for a period of time, dehydration, drying, and sieving treatments are carried out to obtain activated carbon.

[0025] The second technical solution of the present invention is to provide an activated carbon obtained by the preparation method described in the first technical solution above.

[0026] The third technical solution of the present invention is to provide an application of the activated carbon described in the second technical solution above. The activated carbon is used in the fields of wastewater treatment and industrial catalysis.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) Compared with the traditional two-step method for preparing activated carbon by first roasting and carbonizing, impregnating, and then roasting and activating, the one-step activation method using glucose as the precursor in the present invention can significantly reduce the preparation cost, simplify the process flow, and at the same time improve the pore structure and adsorption performance of the activated carbon.

[0029] (2) Glucose, as one of the most widely distributed and important monosaccharides in nature, has the characteristics of being non-toxic, harmless, cheap, and easily available. And by using glucose to prepare activated carbon in the present invention, glucose that might otherwise be regarded as waste can be converted into valuable activated carbon products, thereby reducing production costs, improving economic benefits, and realizing the effective utilization of resources.

[0030] (3) The method for preparing activated carbon provided by the present invention is simple, has a certain generality, and the raw materials are all environmentally friendly materials. No harmful substances are generated during the preparation and use processes, reducing the treatment cost and environmental pollution. These advantages make glucose one of the ideal precursors for preparing activated carbon. Description of the Drawings

[0031] Figure 1 FT-IR diagrams of activated carbon after roasting at different hydrothermal temperatures, where (a) is the activated carbon of Example 3; (b) is the activated carbon of Example 1; (c) is the activated carbon of Comparative Example 1.

[0032] Figure 2 SEM diagram of the activated carbon of Example 1.

[0033] Figure 3 N2 adsorption / desorption isotherm of glucose-activated carbon for Experimental Example 1.

[0034] Figure 4 Adsorption and degradation diagrams of methylene blue by activated carbons calcined at different hydrothermal temperatures, where (a) is the activated carbon of Example 3; (b) is the activated carbon of Example 1; (c) is the activated carbon of Comparative Example 1. Detailed implementation manners

[0035] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented on the premise of the technical solution of the present invention, and gives detailed implementation manners and specific operation processes, but the protection scope of the present invention is not limited to the following embodiments.

[0036] In the following examples and comparative examples, unless otherwise specified for raw materials or treatment techniques, it means that they are all conventional commercially available raw material products or conventional treatment techniques in the art.

[0037] Example 1

[0038] This example provides a method for preparing activated carbon from glucose, which includes the following steps:

[0039] (1) Glucose and aluminum nitrate nonahydrate were added to a reaction kettle in a molar ratio of 1.6:1, and then placed in an electrothermal constant temperature blast drying oven for hydrothermal treatment at 180 °C for 20 h. After the reaction was completed, the obtained brown solid was centrifuged and filtered, and then repeatedly rinsed three times with deionized water and ethanol in a suction filter, and dried in a drying oven for 3 h to obtain a glucose-aluminum hydroxide precursor.

[0040] (2) The obtained product was placed in a tubular furnace and calcined at 550 °C for 4 h in a nitrogen atmosphere to obtain a complex of activated carbon-aluminum oxide.

[0041] (3) The obtained complex was acidified with 10% hydrochloric acid for 10 hours, washed with deionized water until the pH value was about 7, and then dried in an oven to constant weight to obtain activated carbon.

[0042] Example 2

[0043] This example provides a method for preparing activated carbon from glucose, which includes the following steps:

[0044] (1) Glucose and aluminum nitrate nonahydrate were added to a reaction kettle in a molar ratio of 5.2:1, and then placed in an electrothermal constant temperature blast drying oven for hydrothermal treatment at 180 °C for 20 h. After the reaction was completed, the obtained brown solid was centrifuged and filtered, and then repeatedly rinsed three times with deionized water and ethanol in a suction filter, and dried in a drying oven for 3 h to obtain a glucose-aluminum hydroxide precursor.

[0045] (2) Put the obtained product into a tube furnace and calcine it at 550 °C for 4 h in a nitrogen atmosphere to obtain an activated carbon-aluminum oxide composite.

[0046] (3) Acidify the obtained composite with 10% hydrochloric acid for 10 hours, wash it with deionized water until the pH value is about 7, and dry it in an oven to constant weight to obtain activated carbon.

[0047] Example 3

[0048] This example provides a method for preparing activated carbon from glucose, which includes the following steps:

[0049] (1) Add glucose and aluminum nitrate nonahydrate to a reaction kettle in a molar ratio of 1.6:1, then place it in an electrothermal constant temperature forced air drying oven for hydrothermal treatment at 140 °C for 20 h. After the reaction is completed, centrifuge and filter the obtained brown solid, and repeat rinsing three times with deionized water and ethanol respectively in a suction filter, and dry it in a drying oven for 3 h to obtain a glucose-aluminum hydroxide precursor.

[0050] (2) Put the obtained product into a tube furnace and calcine it at 550 °C for 4 h in a nitrogen atmosphere to obtain an activated carbon-aluminum oxide composite.

[0051] (3) Acidify the obtained composite with 10% hydrochloric acid for 10 hours, wash it with deionized water until the pH value is about 7, and dry it in an oven to constant weight to obtain activated carbon.

[0052] Example 4

[0053] This example provides a method for preparing activated carbon from glucose, which includes the following steps:

[0054] (1) Add glucose and aluminum nitrate nonahydrate to a reaction kettle in a molar ratio of 5.2:1, then place it in an electrothermal constant temperature forced air drying oven for hydrothermal treatment at 140 °C for 20 h. After the reaction is completed, centrifuge and filter the obtained brown solid, and repeat rinsing three times with deionized water and ethanol respectively in a suction filter, and dry it in a drying oven for 3 h to obtain a glucose-aluminum hydroxide precursor.

[0055] (2) Put the obtained product into a tube furnace and calcine it at 550 °C for 4 h in a nitrogen atmosphere to obtain an activated carbon-aluminum oxide composite.

[0056] (3) Acidify the obtained composite with 10% hydrochloric acid for 10 hours, wash it with deionized water until the pH value is about 7, and dry it in an oven to constant weight to obtain activated carbon.

[0057] Comparative Example 1

[0058] This embodiment provides a method for preparing activated carbon from glucose, comprising the following steps:

[0059] (1) Glucose and aluminum nitrate nonahydrate are added to a reaction kettle in a molar ratio of 1.6:1, and then placed in an electrothermal constant temperature forced air drying oven for hydrothermal treatment at 180 °C for 20 h. After the reaction is completed, the obtained brown solid is centrifuged and filtered, and then repeatedly rinsed three times with deionized water and ethanol respectively in a suction filter, and dried in a drying oven for 3 h to obtain a glucose-aluminum hydroxide precursor.

[0060] (2) The obtained product is placed in a tubular furnace and calcined at 550 °C for 4 h in a nitrogen atmosphere to obtain an activated carbon-aluminum oxide composite.

[0061] (3) The obtained composite is acidified with 10% hydrochloric acid for 1 hour, washed with deionized water until the pH value is about 7, and then dried in an oven to constant weight to obtain activated carbon.

[0062] Comparative Example 2

[0063] This embodiment provides a method for preparing activated carbon from glucose, comprising the following steps:

[0064] (1) Glucose and aluminum nitrate nonahydrate are added to a reaction kettle in a molar ratio of 5.2:1, and then placed in an electrothermal constant temperature forced air drying oven for hydrothermal treatment at 180 °C for 20 h. After the reaction is completed, the obtained brown solid is centrifuged and filtered, and then repeatedly rinsed three times with deionized water and ethanol respectively in a suction filter, and dried in a drying oven for 3 h to obtain a glucose-aluminum hydroxide precursor.

[0065] (2) The obtained product is placed in a tubular furnace and calcined at 550 °C for 4 h in a nitrogen atmosphere to obtain an activated carbon-aluminum oxide composite.

[0066] (3) The obtained composite is acidified with 10% hydrochloric acid for 1 hour, washed with deionized water until the pH value is about 7, and then dried in an oven to constant weight to obtain activated carbon.

[0067] Comparative Example 3

[0068] This embodiment provides a method for preparing activated carbon from glucose, comprising the following steps:

[0069] (1) Glucose and aluminum nitrate nonahydrate are added to a reaction kettle in a molar ratio of 1.6:1, and then placed in an electrothermal constant temperature forced air drying oven for hydrothermal treatment at 140 °C for 20 h. After the reaction is completed, the obtained brown solid is centrifuged and filtered, and then repeatedly rinsed three times with deionized water and ethanol respectively in a suction filter, and dried in a drying oven for 3 h to obtain a glucose-aluminum hydroxide precursor.

[0070] (2) The obtained product was placed in a tubular furnace and calcined at 550 °C for 4 h in a nitrogen atmosphere to obtain an activated carbon-aluminum oxide composite.

[0071] (3) The obtained composite was acidified with 10% hydrochloric acid for 1 hour, washed with deionized water until the pH value was about 7, and then dried in an oven to constant weight to obtain activated carbon.

[0072] Comparative Example 4

[0073] This example provides a method for preparing activated carbon from glucose, which includes the following steps:

[0074] (1) Glucose and aluminum nitrate nonahydrate were added to a reaction kettle in a molar ratio of 5.2:1, and then hydrothermally treated at 140 °C for 20 h in an electrothermal constant temperature forced air drying oven. After the reaction was completed, the obtained brown solid was centrifuged and filtered, and rinsed three times with deionized water and ethanol respectively in a suction filter, and then dried in a drying oven for 3 h to obtain a glucose-aluminum hydroxide precursor.

[0075] (2) The obtained product was placed in a tubular furnace and calcined at 550 °C for 4 h in a nitrogen atmosphere to obtain an activated carbon-aluminum oxide composite.

[0076] (3) The obtained composite was acidified with 10% hydrochloric acid for 1 hour, washed with deionized water until the pH value was about 7, and then dried in an oven to constant weight to obtain activated carbon.

[0077] The activated carbon prepared in Examples 1-4 and Comparative Examples 1-4 was analyzed as follows:

[0078] For the activated carbon treated at different hydrothermal temperatures and acidification times, infrared analysis was carried out as Figure 1 shown. Curve a represents the activated carbon prepared in Example 3, curve b represents the activated carbon prepared in Example 1, and curve c represents the activated carbon prepared in Comparative Example 1. It can be seen that there is a peak in curve b in the high wavenumber region (3300-2900 cm -1 ), which should be caused by the stretching vibration of the C-H bond. There is no obvious peak in curve a, indicating that compared with the hydrothermal treatment at 140 °C, more aluminum oxide and other organic substances were removed at 180 °C, and more pore structures appeared. The peak of curve c is relatively weak, which may be due to insufficient acidification time, resulting in impure activated carbon with impurities. In the range of 1700-1750 cm -1 This band usually represents the C=O stretching vibration, which is the characteristic peak of carbonyl groups (such as ketones, aldehydes, carboxylic acids, esters). No characteristic peaks appear in the three curves in this band, indicating that during the treatment process, the carbonyl structure in the glucose molecule may have been removed or destroyed, and the original structure of glucose no longer exists. In the range of 1500-1600 cm -1In the waveband, there are obvious peaks in the a and c curves, indicating the stretching vibration of aromatic rings or C=C double bonds. At the same time, in the range of 500 - 900 cm -1 The small peaks in this region (usually C-H bending vibration, especially the C-H rocking vibration on substituted aromatic rings) contrast with the peaks in the 1500 - 1600 cm -1 waveband, proving that after the roasting of glucose, some of its existing structures may be transformed into aromatic rings or C=C double bonds, coexisting with activated carbon. However, there is no peak in the b curve in the 1500 - 1600 cm -1 range, indicating that after hydrothermal synthesis at 180°C and then 10 h of acidification treatment, glucose and other impurities are treated more thoroughly, and a relatively pure activated carbon sample can be obtained.

[0079] Figure 2 Figure 10 is the scanning electron microscope image of the activated carbon in Experimental Example 1. It can be observed from the figure that the surface of the activated carbon raw material is rough and irregular, with different cracks and gaps, and the pore structure is relatively developed. Gases such as CO2 and water vapor generated during the activation process will also increase the number of pores in the activated carbon powder, making it present a sponge-like structure. This makes it easier for adsorbate molecules to enter the pores, helping to improve the adsorption efficiency. More importantly, the pores can also enhance the continuous flow of the adsorbate, thus better adsorbing some tiny substances to be removed.

[0080] Figure 3 Figure 14 is the N2 adsorption / desorption isotherm of the activated carbon in Experimental Example 1, showing typical physical adsorption characteristics. As the relative pressure increases, the adsorption amount gradually increases; while as the relative pressure decreases, the desorption amount gradually decreases. When the relative pressure is relatively low (such as P / Po < 0.1), the increase in the adsorption amount is relatively slow, which may be due to monolayer adsorption occurring mainly at this time. When the relative pressure increases to a certain extent (such as P / Po > 0.5), the increase rate of the adsorption amount accelerates, which may be due to the start of multilayer adsorption and the contribution of mesopores and larger pores in the activated carbon. There is a certain hysteresis phenomenon between the desorption curve and the adsorption curve, which is one of the characteristics of typical physical adsorption isotherms, indicating that the pore structure of the activated carbon has changed during the adsorption and desorption processes.

[0081] Figure 4Adsorption and degradation diagrams of activated carbon roasted after hydrothermal treatment at different temperatures for methylene blue. Curve a represents the activated carbon prepared in Example 3, curve b represents the activated carbon prepared in Example 1, and curve c represents the activated carbon prepared in Comparative Example 1. It can be seen that the activated carbon prepared by the present invention has good adsorption performance. Looking at curves a and b at different temperatures, the activated carbon obtained by hydrothermal treatment at 180°C has better adsorption performance than that obtained by treatment at 140°C. Comparing curves b and c at the same temperature, acidifying the activated carbon for 10 h can obtain a better adsorption effect. This may be because hydrochloric acid reacts with the alumina loaded on the surface of the activated carbon to remove it, expanding the specific surface area of the activated carbon and further enhancing the adsorption capacity of the activated carbon.

[0082] The above description of the embodiments is for the convenience of those of ordinary skill in the art to understand and use the invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative efforts. Therefore, the present invention is not limited to the above embodiments, and the improvements and modifications made by those skilled in the art without departing from the scope of the present invention according to the disclosure of the present invention should be within the protection scope of the present invention.

Claims

1. A method for preparing activated carbon from glucose, characterized in that, It includes the following steps: S1. Mix glucose and an aluminum salt, and obtain a glucose-aluminum hydroxide precursor after hydrothermal reaction; S2. Heat and roast the glucose-aluminum hydroxide precursor obtained in step S1 under an anaerobic environment to obtain an activated carbon-aluminum oxide composite; S3. Acidify the activated carbon-aluminum oxide composite obtained in step S2 to obtain activated carbon.

2. The method for preparing activated carbon from glucose according to claim 1, characterized in that, In step S1, the molar ratio of the aluminum salt to glucose is 1:(0.8 - 6.4).

3. The method for preparing activated carbon from glucose according to claim 2, wherein, In step S1, the aluminum salt is selected from any one of aluminum nitrate and aluminum nitrate nonahydrate.

4. The method for preparing activated carbon from glucose according to claim 1, characterized in that, In step S1, the temperature of the hydrothermal reaction is 100 - 200 °C, and the time of the hydrothermal reaction is 10 - 20 h.

5. The method for preparing activated carbon from glucose according to claim 1, characterized in that, In step S2, the roasting temperature is 500 - 550 °C, and the roasting time is 2 - 5 h.

6. The method for preparing activated carbon from glucose according to claim 1, wherein In step S2, the protective gas for the anaerobic environment is nitrogen and / or argon.

7. The method for preparing activated carbon from glucose according to claim 1, wherein, In step S3, the concentration of the acidification treatment is 5% - 15%, and the time of the acidification treatment is 5 - 12 h.

8. The method for preparing activated carbon from glucose according to claim 7, characterized in that, In step S3, the solution used for acidification is hydrochloric acid.

9. An activated carbon, characterized in that, Prepared by the method according to any one of claims 1 - 8.

10. Use of activated carbon as described in claim 9, characterized in that, The activated carbon is used in the fields of wastewater treatment and industrial catalysis.

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