A magnetic cattle hair-based biomass activated carbon and its preparation method and application

Abstract

The present invention discloses a magnetic yak hair-based biomass activated carbon, as well as its preparation method and application. The magnetic yak hair-based activated carbon is prepared by a two-step process of mixing Fenton iron mud with yak hair activated carbon, based on the carbonization and activation of yak hair. The activated carbon has a maximum specific surface area of ​​2632 m² / g and can be separated from a solution using magnetism. It can be used for the efficient adsorption of water pollutants such as organic dyes and antibiotics.

Description

Technical Field

[0001] The invention relates to magnetic ox-hair-based biomass activated carbon and a preparation method and application thereof, belonging to the technical field of development and utilization of renewable resources and preparation of adsorption materials. Background Art

[0002] Activated carbon is widely used in water treatment due to its high specific surface area, excellent adsorption properties, and good biocompatibility. However, conventional activated carbon faces difficulties in separation and recycling after use. The emergence of magnetic activated carbon offers a new approach to addressing this problem. Cow hair, a plentiful biomass waste rich in carbon, has the potential to serve as an activated carbon raw material. Converting cow hair into magnetic activated carbon not only transforms animal waste resources but also provides an efficient, low-cost, and easily recyclable adsorption material for water treatment and water resource conservation.

[0003] The inventors first searched for relevant research on hair-based activated carbon. In terms of papers, in 2017, Ahmed et al. used a high-temperature furnace carbonization method to prepare a high-specific-surface-area porous carbon material derived from human hair (BioresourceTechnology, 2017, 243, 778-784); in 2020, Sani et al. used chicken feathers and eggshells to synthesize a new type of magnetized activated carbon for adsorbing heavy metal ions (BioresourceTechnology, 2020, 297); in 2021, Seyed et al. used human hair as a carbon precursor to prepare a mesoporous activated carbon with an average pore size of 2.42 nm, which was used for Ni 2+ The average adsorption rate is between 0.828 and 8.917 mg / g (Current Opinion in Green and Sustainable Chemistry, 2021, 4: 100141). Secondly, the inventors also searched for research related to magnetic activated carbon. In terms of papers, Zhu Guangyao's master's thesis at Tianjin University of Science and Technology prepared magnetic activated carbon by mixing black leaf lignin and Fenton sludge in a one-step method, and explored its magnetic mechanism; in terms of patents, the invention with application number 202210697481.0 calcined pre-carbonized bean cake and potassium iron oxalate, and the product was washed with water, separated by a magnet and dried to obtain magnetic activated carbon. The invention with application number 202310582060.8 uses oil sludge and desulfurization ash to prepare magnetic activated carbon powder. In the above studies, plant charcoal was used as the precursor carbon material for the preparation of magnetic activated carbon, and there are no magnetized products for hair-type activated carbon. At the same time, the specific surface area and adsorption effect of hair-based activated carbon, as well as the adsorption effect of magnetized plant-based activated carbon, have not achieved ideal results.

[0004] In addition, the inventors also summarized the magnetization process during the preparation of magnetic activated carbon. For example, the co-precipitation method adjusts the pH value of the solution to allow iron ions to co-precipitate on the surface of activated carbon to form magnetic oxides, thereby simplifying the operation process. The sol-gel method generates uniformly distributed nanomagnetic particles by controlling the reaction conditions of the solution, providing a more precise preparation method for the material. The mechanical mixing method uses physical mixing to uniformly attach magnetic nanoparticles to the surface of activated carbon, which is convenient and suitable for rapid mass production. In related work, Zhu et al. used Fenton iron mud as a precursor for magnetic materials, and prepared magnetic activated carbon in one step by high-temperature pyrolysis at 800°C in a tube furnace (Journal of Environmental Chemical Engineering, 2021, 9, 106538). Compared with traditional activated carbon preparation methods, this process can generate magnetic nanoparticles in situ from iron compounds in the mixture during the high-temperature carbonization process, successfully achieving the magnetization of the material. However, the pure activated carbon produced by this method has a BET value of 1992 m² / g, while the BET value of magnetic activated carbon is 1099 m² / g. The incorporation of Fenton causes the pores and carbon walls of the magnetic activated carbon to collapse, while the iron-based particles block the pores, resulting in a decrease in porosity and pore volume. Therefore, further optimization is needed to produce magnetic activated carbon with a higher specific surface area. The present invention adopts a two-step preparation method. First, the pure activated carbon obtained has a BET value of 922 m² / g. Then, Fenton iron mud is doped on this basis and reacted at high temperature to obtain a magnetic activated carbon with a BET value of 2632 m² / g. By separating the activation and magnetization processes, this method successfully avoids the decrease in porosity caused by the reaction between the activator and the magnetizer. At the same time, the magnetization process further promotes the expansion and formation of pores and produces finer iron-based particles, thereby avoiding the problem of pore blockage and significantly improving the porosity of the magnetic activated carbon. This method successfully takes into account the high porosity of the magnetic activated carbon and the coexistence of magnetic particles.

[0005] Yak hair is a source of livestock waste in Northwest China. Large-scale storage and incineration of this waste can cause environmental pollution. This invention proposes a method that combines activation and magnetization, using yak hair as a carbon source, to produce magnetic yak hair-based biomass activated carbon. This method facilitates the sustainable utilization of yak hair waste and can be used to treat environmental pollutants, demonstrating promising industrial applications. Summary of the Invention

[0006] The purpose of the present invention is to provide a magnetic yak hair-based biomass activated carbon and a preparation method and application thereof.

[0007] The present invention discloses a method for preparing highly adsorbable magnetic yak hair-based biomass activated carbon. The method adopts a two-step activation and magnetization process to prepare highly adsorbable magnetic activated carbon. The specific steps are as follows:

[0008] ① Carbonization: Wash the yak hair with ultrapure water, dry it, and heat it to 250-350℃ under nitrogen atmosphere at a heating rate of 3-5℃ / min for 1-2 hours for carbonization.

[0009] ② Activation: The carbonized material obtained in step ① was mixed with KOH and heated to 600°C-800°C under a nitrogen atmosphere at a heating rate of 3-5°C / min. The mixture was kept warm for 0.5-1 hour. The pH was adjusted to neutral with HCl, and the mixture was washed and dried to obtain ox-hair-based activated carbon. The mass ratio of carbonized material to KOH was 1:1-1:4. The oxidation reaction time was 1.5-4 hours.

[0010] ③ Preparation of Fenton iron mud: Ferrous sulfate heptahydrate is dissolved in ultrapure water to obtain a ferrous sulfate heptahydrate solution, which is then mixed with hydrogen peroxide for oxidation reaction at room temperature. After the reaction is completed, the pH is adjusted to neutral with HCl, and the supernatant is removed by centrifugation to obtain Fenton iron mud; the concentration of hydrogen peroxide is 30%, and the concentration of ferrous sulfate heptahydrate solution is 0.5-0.8 mol / L; the volume ratio of ferrous sulfate heptahydrate solution to hydrogen peroxide is 1:1-1:2.

[0011] ④ Magnetic Activated Carbon: Mix the yak hair-based activated carbon prepared in step ② with the Fenton iron sludge prepared in step ③ in a mass ratio of 1:1 to 1:4. The mixture is then reacted at 300°C to 600°C. After washing and drying, magnetic yak hair-based activated carbon is obtained. The high-temperature reaction time is 1.5 to 4 hours.

[0012] The magnetic yak hair-based biomass activated carbon prepared by this invention has a maximum specific surface area of ​​2632 m² / g and a pore size ranging from 0.889 nm to 33.242 nm, exhibiting a magnetic and porous structure. The magnetic activated carbon is used for efficient adsorption of methylene blue and tetracycline, demonstrating excellent adsorption performance and high adsorption capacity. It can also be separated from solutions using magnetism and can be used for efficient adsorption of water pollutants such as organic dyes and antibiotics. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 The scanning electron microscope image and magnetic verification image of the yak hair-based magnetic activated carbon prepared in Example 1.

[0014] Figure 2 The scanning electron microscope image and magnetic verification image of the yak hair-based magnetic activated carbon prepared in Example 2.

[0015] Figure 3 The scanning electron microscope image and magnetic verification image of the yak hair-based magnetic activated carbon prepared in Example 3.

[0016] Figure 4 These are the scanning electron microscope images and magnetic verification images of the yak hair-based magnetic activated carbon prepared in Example 4.

[0017] Figure 5 This is a diagram showing the adsorption effect of magnetic yak hair-based biomass activated carbon on methylene blue in Example 5.

[0018] Figure 6 This is a diagram showing the adsorption effect of tetracycline by magnetic yak hair-based biomass activated carbon in Example 6. DETAILED DESCRIPTION

[0019] The present invention will be further described below with reference to specific embodiments.

[0020] Example 1

[0021] ① Wash the yak hair with ultrapure water, dry it, and chop 100g of the dried yak hair into pieces with an average length of about 3cm. Heat the treated yak hair in a tube furnace under a nitrogen atmosphere at a heating rate of 5℃ / min to 300℃ and hold it for 2 hours to obtain a carbonized product.

[0022] ② The carbonized product was mixed with KOH in a mass ratio of 1:2, and heated to 600°C under a nitrogen atmosphere for 0.5 hours. The pH was adjusted to neutral with HCl, washed with ultrapure water, and dried to obtain yak-based biomass activated carbon.

[0023] ③ Mix 50 mL of 0.66 mol / L ferrous sulfate heptahydrate solution with 50 mL of 30% hydrogen peroxide and perform oxidation reaction at room temperature. After 0.5 h of reaction, adjust the pH to neutral with HCl. Centrifuge at 8000 rpm for 10 min, remove the supernatant, and obtain iron sludge precipitation.

[0024] ④ After mixing yak hair-based biomass activated carbon and Fenton iron mud in a mass ratio of 1:3 under a magnetic stirrer for 1 hour, nitrogen was introduced into a tube furnace and heated to 600°C for 1.5 hours. After washing and drying, yak hair-based magnetic biomass activated carbon was obtained.

[0025] Figure 1 (a) shows a scanning electron micrograph of the magnetic yak hair-based biomass activated carbon prepared in Example 1. Figure 1 (b) is a magnetic effect diagram of the magnetic activated carbon prepared in this example. The results show that the activated carbon has a certain void structure, but the number of voids is small and the magnetic effect of the magnetic activated carbon is average, with a portion of material at the bottom that cannot be magnetically separated.

[0026] The test results show that the specific surface area of ​​the product is 251.82 m² / g. 10 mg of the prepared magnetic yak hair-based biomass activated carbon was mixed with 10 mL of methylene blue and tetracycline solution with a concentration of 1200 mg / L, respectively, and placed in a 30°C constant temperature water bath shaker and shaken at 300 r / min for 300 minutes. The maximum adsorption capacity for methylene blue was 81.61 mg / g, and the maximum adsorption capacity for tetracycline was 56.76 mg / g.

[0027] Example 2

[0028] ① Wash the yak hair with ultrapure water, dry it, and chop 50g of the dried yak hair into pieces with an average length of about 3cm. Heat the treated hair to 300℃ at a heating rate of 5℃ / min under a nitrogen atmosphere and keep it at that temperature for 2 hours to obtain a carbonized product.

[0029] ② Mix the carbonized product in step ① with KOH in a mass ratio of 1:2, heat to 600°C under a nitrogen atmosphere, and keep warm for 0.5 hours;

[0030] ③ Mix 50 mL of 0.66 mol / L ferrous sulfate heptahydrate solution with 50 mL of 30% hydrogen peroxide and perform oxidation reaction at room temperature. After 0.5 h of reaction, adjust the pH to neutral with HCl. Centrifuge at 8000 rpm for 10 min, remove the supernatant, and obtain iron sludge precipitation.

[0031] ④ Yak hair, biomass activated carbon and Fenton iron mud were mixed in a mass ratio of 1:3 under a magnetic stirrer for 1 hour and then heated to 600℃ in a tube furnace for 2.5 hours. After washing and drying, magnetic yak hair-based magnetic activated carbon was obtained.

[0032] Figure 2 (a) shows the scanning electron microscope image and magnetic result image of the magnetic yak hair-based biomass activated carbon prepared in Example 2. Figure 2 (b) shows the magnetic effect of the magnetic activated carbon prepared in this example. The results show that the magnetic activated carbon has large voids, and the magnetic test results show that the activated carbon cannot achieve complete magnetic removal within a certain distance.

[0033] The test results show that the specific surface area of ​​the magnetic activated carbon is 562.49 m² / g. 10 mg of the prepared magnetic yak hair-based biomass activated carbon was mixed with 10 mL of methylene blue and tetracycline solution with a concentration of 1200 mg / L, respectively, and placed in a 30°C constant temperature water bath shaker and shaken at 300 r / min for 300 min. The maximum adsorption capacity for methylene blue was 381.61 mg / g, and the maximum adsorption capacity for tetracycline was 431.42 mg / g.

[0034] Example 3

[0035] ① Wash the yak hair with ultrapure water, dry it, and chop 50g of the dried yak hair into pieces with an average length of approximately 3cm. Heat the treated hair to 300℃ under a nitrogen atmosphere at a heating rate of 3℃ / min and hold for 2h to obtain the yak hair carbonization product.

[0036] ② Mix the carbonized yak hair product from step ① with KOH in a mass ratio of 1:3, continue heating to 800°C under a nitrogen atmosphere, and keep warm for 0.5h;

[0037] ③ Take 50 mL of 0.66 mol / L ferrous sulfate heptahydrate solution and mix it with 50 mL of 30% hydrogen peroxide for oxidation reaction at room temperature. After 1 hour of reaction, adjust the pH to neutral with HCl. Centrifuge at 8000 rpm for 10 minutes, remove the supernatant and obtain iron sludge precipitation.

[0038] ④ Yak hair-based biomass activated carbon and Fenton iron mud were mixed in a mass ratio of 1:2 under a magnetic stirrer for 1 hour, then heated to 600℃ in a tube furnace for 4 hours. After washing and drying, magnetic yak hair-based biomass activated carbon was obtained.

[0039] Figure 3 (a) shows a scanning electron microscope image of the magnetic activated carbon prepared in this example. The results show that although the magnetic activated carbon has a relatively large void structure, some of the voids are collapsed. Figure 3 (b) is a magnetic effect diagram of the magnetic activated carbon, and the results show that the magnetic properties of the material are poor.

[0040] The adsorption test results show that the specific surface area of ​​the product is 745.273 mg 2 / g, 10 mg of the prepared magnetic yak hair-based biomass activated carbon was mixed with 10 mL of methylene blue and tetracycline solution with a concentration of 1200 mg / L, respectively, and placed in a 30°C constant temperature water bath shaker and shaken at 300 r / min for 300 min. The maximum adsorption capacity for methylene blue was 556.77 mg / g, and the adsorption capacity for tetracycline was 793.85 mg / g.

[0041] Example 4

[0042] ① Wash yak hair with ultrapure water and dry it. Take 50g of the dried yak hair and chop it into pieces with an average length of approximately 3 cm. Heat the treated hair to 300°C in a nitrogen atmosphere at a heating rate of 5°C / min and hold for 2 hours to obtain a carbonized product.

[0043] ② Mix the carbonized product with KOH in a mass ratio of 1:4, continue heating to 800°C under a nitrogen atmosphere, and keep warm for 0.5 hours.

[0044] ③ Take 50 mL of 0.66 mol / L ferrous sulfate heptahydrate solution and mix it with 50 mL of 30% hydrogen peroxide for oxidation reaction at room temperature. After 1 hour of reaction, adjust the pH to neutral with HCl. Centrifuge at 8000 rpm for 10 minutes, remove the supernatant and obtain iron sludge precipitation.

[0045] ④ Yak hair-based biomass activated carbon and Fenton iron mud were mixed in a 1:1 mass ratio under a magnetic stirrer for 1 hour and then heated to 800°C in a tube furnace for 4 hours. After washing and drying, the resulting activated carbon exhibited magnetic properties.

[0046] like Figure 4 (a) is a scanning electron microscope image of the yak hair base prepared in this embodiment. Figure 5 (b) is the magnetic effect diagram of magnetic activated carbon. The results show that the magnetic activated carbon has a rich void structure and excellent magnetic properties.

[0047] The test results show that the specific surface area of ​​the product is 2632 m² / g. 10 mg of the prepared magnetic yak hair-based biomass activated carbon was mixed with 10 mL of methylene blue and tetracycline solution with a concentration of 1200 mg / L, respectively, and placed in a 30°C constant temperature water bath shaker and shaken at 300 r / min for 300 min. The maximum adsorption capacity for methylene blue was 996.54 mg / g, and the maximum adsorption capacity for tetracycline was 1114.52 mg / g.

[0048] Example 5

[0049] ① Wash yak hair with ultrapure water and dry it. Take 50g of the dried yak hair and chop it into pieces with an average length of approximately 3 cm. Heat the treated hair to 300°C in a nitrogen atmosphere at a heating rate of 5°C / min and hold for 2 hours to obtain a carbonized product.

[0050] ② Mix the carbonized product with KOH in a mass ratio of 1:4, continue heating to 800 °C under a nitrogen atmosphere, and keep warm for 0.5 hours.

[0051] ③ Take 50 mL of 0.66 mol / L ferrous sulfate heptahydrate solution and mix it with 50 mL of 30% hydrogen peroxide for oxidation reaction at room temperature. After 1 hour of reaction, adjust the pH to neutral with HCl. Centrifuge at 8000 rpm for 10 minutes, remove the supernatant and obtain iron sludge precipitation.

[0052] ④ Yak hair-based biomass activated carbon and Fenton iron mud were mixed in a 1:1 mass ratio under a magnetic stirrer for 1 hour and then heated to 800°C in a tube furnace for 4 hours. After washing and drying, the resulting activated carbon exhibited magnetic properties.

[0053] 10 mg of the magnetic yak hair-based biomass activated carbon prepared as above was mixed with 10 mL of a 1000 mg / L methylene blue solution and placed in a 30°C constant temperature water bath shaker. The mixture was shaken at 300 r / min for 600 min. A small amount of the suspension was taken for magnetic separation at time intervals of 10, 15, 20, 50, 100, 150, 200, 250, 300, 350, 400, 450, 500, and 600 min, and the methylene blue concentration was analyzed. Figure 5 The adsorption kinetics curve of methylene blue by the magnetic activated carbon is shown in Fig. 2. The maximum adsorption capacity of methylene blue by the magnetic activated carbon is 996.54 mg / g according to the first-order kinetic equation fitting.

[0054] Example 6

[0055] ① Wash yak hair with ultrapure water and dry it. Take 50g of the dried yak hair and chop it into pieces with an average length of approximately 3 cm. Heat the treated hair to 300°C in a nitrogen atmosphere at a heating rate of 5°C / min and hold for 2 hours to obtain a carbonized product.

[0056] ② Mix the carbonized product with KOH in a mass ratio of 1:4, continue heating to 800 °C under a nitrogen atmosphere, and keep warm for 0.5 hours.

[0057] ③ Take 50 mL of 0.66 mol / L ferrous sulfate heptahydrate solution and mix it with 50 mL of 30% hydrogen peroxide for oxidation reaction at room temperature. After 1 hour of reaction, adjust the pH to neutral with HCl. Centrifuge at 8000 rpm for 10 minutes, remove the supernatant and obtain iron sludge precipitation.

[0058] ④ Yak hair-based biomass activated carbon and Fenton iron mud were mixed in a 1:1 mass ratio under a magnetic stirrer for 1 hour and then heated to 800°C in a tube furnace for 4 hours. After washing and drying, the resulting activated carbon exhibited magnetic properties.

[0059] 10 mg of the magnetic yak hair-based biomass activated carbon prepared as above was mixed with 10 mL of a 1200 mg / L tetracycline solution and placed in a 30°C constant temperature water bath shaker. The mixture was shaken at 300 r / min for 600 min. A small amount of the suspension was taken for magnetic separation at time intervals of 10, 15, 20, 50, 100, 150, 200, 250, 300, 350, 400, 450, 500, and 600 min, and the tetracycline concentration was analyzed. Figure 6 The figure shows the adsorption kinetics curve of tetracycline by the magnetic activated carbon. According to the first-order kinetic equation fitting, the maximum adsorption capacity of tetracycline by the magnetic activated carbon is 1114.52 mg / g.

Claims

1. A method for preparing magnetic yak hair-based biomass activated carbon, comprising the following steps: ① Carbonization: Wash the yak hair with ultrapure water, dry it, and heat it to 250-350℃ at a heating rate of 3-5℃ / min under a nitrogen atmosphere for 1-2 hours. ② Activation: The carbonized material obtained in step ① is mixed with KOH, and heated to 600°C~800°C at a heating rate of 3~5°C / min under a nitrogen atmosphere, and kept warm for 0.5~1h. The pH is adjusted to neutral with HCl, and then washed and dried to obtain ox-hair-based activated carbon; the mass ratio of carbonized material to KOH is 1:1~1:4; ③ Preparation of Fenton iron mud: ferrous sulfate heptahydrate was dissolved in ultrapure water to obtain a ferrous sulfate heptahydrate solution, which was then mixed with hydrogen peroxide to carry out an oxidation reaction at room temperature. After the reaction was completed, the pH was adjusted to neutral with HCl, and the supernatant was removed by centrifugation to obtain Fenton iron mud; ④ Activated carbon magnetization: The yak hair-based activated carbon prepared in step ② is mixed with the Fenton iron mud in step ③ in a mass ratio of 1:1 to 1:4, and then reacted at a high temperature of 300°C to 600°C for 1.5 to 4 hours. After washing and drying, magnetic yak hair-based activated carbon is obtained.

2. The method for preparing magnetic yak hair-based biomass activated carbon according to claim 1, wherein: In step ③, the concentration of hydrogen peroxide is 30%, the concentration of ferrous sulfate heptahydrate solution is 0.5-0.8 mol / L; and the volume ratio of ferrous sulfate heptahydrate solution to hydrogen peroxide is 1:1-1:

2.

3. The method for preparing magnetic yak hair-based biomass activated carbon according to claim 1, wherein: In step ③, the oxidation reaction time is 0.5~1 h.

4. The magnetic yak hair-based biomass activated carbon prepared by the method according to any one of claims 1 to 3, characterized in that: Yak hair-based biomass activated carbon is magnetic, with a maximum specific surface area of ​​2632 m² / g and a pore size range of 0.889 nm to 33.242 nm.

5. Use of the magnetic yak hair-based biomass activated carbon prepared by the method of claim 1 or the magnetic yak hair-based biomass activated carbon according to claim 4 in the adsorption of methylene blue and tetracycline.

Images