Environmentally friendly regenerated activated carbon and preparation method thereof

Abstract

This invention relates to the field of activated carbon technology, specifically to an environmentally friendly regenerated activated carbon and its preparation method. The invention utilizes chitosan as a framework, combined with the synergistic effects of glacial acetic acid aqueous solution, magnetic silica, a ternary photocatalyst, and glutaraldehyde, to prepare a composite aerogel via freeze-drying. The composite aerogel is then calcined in a muffle furnace to obtain a composite photocatalyst with a three-dimensional network structure. The composite photocatalyst is then uniformly mixed with pretreated activated carbon and deionized water, and calcined in a muffle furnace to obtain the environmentally friendly regenerated activated carbon. The environmentally friendly regenerated activated carbon prepared by this invention not only possesses a high specific surface area and pore structure, providing more adsorption and catalytic active sites, but also exhibits excellent photocatalytic performance, contributing to the efficient removal of environmental pollutants and resource regeneration.

Description

Technical Field

[0001] This invention relates to the field of activated carbon technology, specifically to an environmentally friendly regenerated activated carbon and its preparation method. Background Technology

[0002] With the increasing severity of environmental pollution, waste treatment and resource recycling have become increasingly important. Environmentally friendly recycled activated carbon is a material that can adsorb and remove harmful substances, and its preparation method is of great significance in the field of environmental protection.

[0003] Currently, the regeneration of waste activated carbon includes methods such as thermal regeneration, biological regeneration, microwave regeneration, electrochemical regeneration, and photocatalytic regeneration. Among these, photocatalytic regeneration has attracted much attention due to its high efficiency, environmental friendliness, and sustainability. Photocatalytic regeneration of activated carbon utilizes the properties of photocatalysts to adsorb and photocatalytically degrade harmful substances on waste activated carbon, achieving the regeneration goal. Photocatalysts are typically semiconductor materials, such as titanium dioxide and zinc oxide, possessing excellent light absorption properties and the ability to generate photo-electron-hole pairs. Under illumination, the photocatalyst absorbs light energy, generating reactive oxygen species (such as hydroxyl radicals and superoxide radicals), which react with harmful substances on the surface of the waste activated carbon, degrading and decomposing them into harmless substances. The preparation method of photocatalytically regenerated activated carbon has the advantages of high efficiency, environmental friendliness, and sustainability, effectively degrading and removing harmful substances from waste activated carbon and achieving resource recycling.

[0004] However, traditional photocatalysts suffer from insufficient visible light absorption and low visible light catalytic performance, which limits their application in the preparation of photocatalytic regenerated activated carbon.

[0005] Therefore, we propose an environmentally friendly regenerated activated carbon and its preparation method. Summary of the Invention

[0006] The purpose of this invention is to provide an environmentally friendly regenerated activated carbon and its preparation method to solve the problems mentioned in the background art.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0008] A method for preparing environmentally friendly recycled activated carbon includes the following steps:

[0009] S1: Soak waste activated carbon in deionized water for 12-24 hours, heat to boiling for 10-20 minutes, filter out, wash repeatedly with deionized water until the pH value reaches 6-7, then dry and grind to obtain waste activated carbon powder, add hydrochloric acid and mix evenly, heat to 30-40℃, reflux reaction for 1-2 hours, filter, wash repeatedly, and vacuum dry at 70-80℃ for 2-4 hours to obtain pretreated activated carbon;

[0010] S2: Mix anhydrous ethanol and deionized water evenly, adjust the pH value to 6-7, add nano-iron oxide, ultrasonically disperse for 15-25 min, then add a mixture of tetraethyl orthosilicate and anhydrous ethanol dropwise over 1-2 h, stir evenly at 300-400 r / min, separate and collect under magnetic field, wash multiple times, and vacuum dry at 70-80℃ for 5-7 h to obtain magnetic silica;

[0011] S3: Mix chitosan and glacial acetic acid aqueous solution, ultrasonically disperse for 20-30 min, add magnetic silica, stir evenly at 250-350 r / min, then add ternary photocatalyst and mix evenly, add glutaraldehyde dropwise over 30-40 min to obtain a sol; start at 40-50℃, age the sol to 70-80℃ at a heating rate of 10-20℃ / d, keep it at this temperature for 1-2 days, then soak it in anhydrous ethanol, shake and replace it 2-3 times at room temperature, then soak it in deionized water for 22-24 h, changing the water every 3 h during this period, and freeze-dry for 46-48 h to obtain a composite aerogel; heat the composite aerogel in a muffle furnace from room temperature to 450-550℃ at a rate of 2-5℃ / min, calcine for 2-4 h, and cool to room temperature to obtain a composite photocatalyst;

[0012] S4: Mix the composite photocatalyst, pretreated activated carbon, and deionized water, sonicate for 30-40 minutes, stir evenly at 500-600 r / min, and vacuum dry at 70-80℃ for 12-14 hours to obtain a mixture; calcine the mixture in a muffle furnace at a rate of 2-5℃ / min from room temperature to 500-550℃ for 2-4 hours, and cool to room temperature to obtain environmentally friendly regenerated activated carbon.

[0013] Furthermore, the mass ratio of waste activated carbon powder to hydrochloric acid in S1 is 1:(5-7).

[0014] Furthermore, the particle size of the waste activated carbon powder in S1 is 200-250 mesh.

[0015] Furthermore, the concentration of hydrochloric acid in S1 is 5-10 wt%.

[0016] Furthermore, the mass ratio of anhydrous ethanol to deionized water in S2 is 1:(0.30-0.35).

[0017] Furthermore, the mass of nano-ferric oxide in S2 is 0.12-0.15% of the total mass of anhydrous ethanol and deionized water.

[0018] Furthermore, the mass ratio of nano-ferric oxide and tetraethyl orthosilicate in S2 is 1:(1.5-2.0).

[0019] Furthermore, the mass ratio of tetraethyl orthosilicate to anhydrous ethanol in S2 is 1:(20-30).

[0020] Furthermore, the mass ratio of chitosan to glacial acetic acid aqueous solution in S3 is 1:(70-75).

[0021] Furthermore, the volume fraction of the glacial acetic acid aqueous solution in S3 is 1.5-2.0%.

[0022] Furthermore, the mass of magnetic silica in S3 is 8-10% of the mass of chitosan.

[0023] Furthermore, the mass of the ternary photocatalyst in S3 is 50-60% of the mass of chitosan.

[0024] Furthermore, the preparation method of the ternary photocatalyst in S3 is as follows:

[0025] Step (1): Mix melamine and deionized water, heat to 80-90℃, stir until completely dissolved, add a mixed solution of cyanuric acid and deionized water dropwise over 1-2 hours, evaporate the water and vacuum dry at 100-110℃ for 24-48 hours to obtain a precursor, calcine the precursor in a muffle furnace at a rate of 2-5℃ / min from room temperature to 500-550℃ for 3-4 hours to obtain porous carbon nitride;

[0026] Step (2): Cerium nitrate hexahydrate, potassium bromate, L-asparagine, and porous carbon nitride are mixed evenly, deionized water is added, and the mixture is stirred evenly. The mixture is placed in a 200 mL polytetrafluoroethylene-lined reactor and kept at 140-150 °C for 22-24 h. After cooling to room temperature, the mixture is washed alternately with anhydrous ethanol and deionized water, and then vacuum dried at 70-80 °C for 10-12 h to obtain the composite.

[0027] Step (3): Mix the complex with deionized water, sonicate for 50-60 min, add a mixed solution of zinc nitrate hexahydrate and methanol, stir evenly, then add a mixed solution of 2-methylimidazole and methanol, stir evenly, and after centrifugation, multiple washings and drying, the ternary photocatalyst is obtained.

[0028] In the above technical solution, melamine and cyanuric acid are mixed to prepare a hydrogen-bonded precursor, which is then polymerized at high temperature to obtain a three-dimensional, lamellar, rolled-up porous carbon nitride. The introduction of hydrogen bonds significantly reduces the blocky stacking of graphitic carbon nitride, increases its specific surface area, increases the number of pores, and improves the separation efficiency of photogenerated carriers, thereby enhancing photocatalytic activity. A hydrothermal method is used to prepare a composite of porous carbon nitride and cerium oxide, which effectively inhibits the recombination of photogenerated electrons and holes in carbon nitride, greatly enhancing photocatalytic activity. A room-temperature synthesis method is used to load 2-methylimidazolium zinc MOF (ZIF-8) onto the surface of the composite to prepare a ternary photocatalyst. The Zn of ZIF-8 is then used to generate the photocatalyst. 2+ The strong electrostatic interaction between the N-ions and the in-plane repeating N-ions of the 3-s-triazine ring in porous carbon nitride, as well as the interaction between ZIF-8 and cerium oxide, improves the stability, photocatalytic performance, specific surface area and dispersibility of the composite, thus resulting in better application performance.

[0029] Furthermore, in step (1), the mass ratio of melamine to deionized water is 1:(100-110).

[0030] Furthermore, in step (1), the mass ratio of cyanuric acid to melamine is 1:(1.0-1.5), and the mass ratio of cyanuric acid to deionized water is 1:(100-110).

[0031] Furthermore, in step (2), the mass ratio of cerium nitrate hexahydrate, potassium bromate, L-asparagine, and porous carbon nitride is 1:(3.8-4.0):(1.0-1.2):(1.0-1.5).

[0032] Furthermore, in step (3), the mass of deionized water is 170-175 times the mass of cerium nitrate hexahydrate.

[0033] Furthermore, in step (3), the mass ratio of the complex to deionized water is 1:(30-35).

[0034] Furthermore, in step (3), the mass of zinc nitrate hexahydrate is 1.5-2.0 times the mass of the complex, and the mass ratio of zinc nitrate hexahydrate to methanol is 1:(35-40).

[0035] Furthermore, in step (3), the mass of 2-methylimidazole is 4-5 times the mass of the complex, and the mass ratio of 2-methylimidazole to methanol is 1:(20-30).

[0036] Furthermore, the mass of glutaraldehyde in S3 is 6-8 times that of chitosan.

[0037] Furthermore, the mass ratio of the composite photocatalyst, pretreated activated carbon, and deionized water in S4 is 1:(3-5):(50-60).

[0038] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0039] 1. This invention discloses an environmentally friendly regenerated activated carbon and its preparation method. A hydrogen-bonded precursor is prepared by mixing melamine and cyanuric acid, followed by a high-temperature polymerization reaction to obtain a three-dimensional, lamellar, coiled, stacked porous carbon nitride. The introduction of hydrogen bonds significantly reduces the blocky stacking of graphitic carbon nitride, increasing its specific surface area, the number of pores, and the separation efficiency of photogenerated carriers, thereby improving photocatalytic activity. A hydrothermal method is used to prepare a composite of porous carbon nitride and cerium oxide, effectively inhibiting the recombination of photogenerated electrons and holes in carbon nitride, greatly enhancing photocatalytic activity. A room-temperature synthesis method is used to load 2-methylimidazolium zinc MOF (ZIF-8) onto the surface of the composite to obtain a ternary photocatalyst. The Zn of ZIF-8... 2+ The strong electrostatic interaction between the N-ions and the in-plane repeating N-ions of the 3-s-triazine ring in porous carbon nitride, as well as the interaction between ZIF-8 and cerium oxide, improves the stability, photocatalytic performance, specific surface area and dispersibility of the composite, thus resulting in better application performance.

[0040] 2. The present invention provides an environmentally friendly regenerated activated carbon and its preparation method. By coating nano-ferric oxide with silica, the stability and dispersibility of nano-ferric oxide can be improved, preventing its aggregation and agglomeration. The resulting magnetic silica has excellent magnetic properties and adsorption capacity, which can enhance the adsorption capacity of activated carbon and make it have a better adsorption effect on pollutants such as metal ions.

[0041] 3. This invention provides an environmentally friendly regenerated activated carbon and its preparation method. Chitosan, a natural and environmentally friendly material, serves as the framework, providing stability and structural support for the composite aerogel, helping to maintain its porous structure and shape stability. Simultaneously, the addition of magnetic silica and a ternary photocatalyst synergistically enhances catalytic performance, strengthening the photocatalyst's degradation effect on pollutants. The addition of glutaraldehyde allows for cross-linking with chitosan, forming a three-dimensional network structure that enhances light absorption, making it easier for reactant molecules to reach the active sites, thereby improving reaction rate and efficiency. After freeze-drying and calcination, a composite photocatalyst is obtained. The composite photocatalyst, pretreated activated carbon, and deionized water are mixed uniformly and calcined in a muffle furnace to obtain environmentally friendly regenerated activated carbon with excellent photocatalytic performance and a high specific surface area. This invention, through the synergistic effect of multiple components, can improve the adsorption capacity and photocatalytic performance of activated carbon, contributing to the efficient removal of environmental pollutants and resource recycling. Detailed Implementation

[0042] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] In this embodiment, the waste activated carbon was sourced from Shenzhen Juneng Graphite Recycling Co., Ltd.; the nano-iron oxide (Fe3O4) had a content of ≥99.9% and a size of 10-20nm and was sourced from Beijing Zhongke Keyou Technology Co., Ltd.; and the chitosan was food-grade and sourced from Jiangsu Gubei Biotechnology Co., Ltd.

[0044] Example 1: A method for preparing environmentally friendly recycled activated carbon, comprising the following processes:

[0045] S1: Soak the waste activated carbon in deionized water for 12 hours, heat to boiling for 10 minutes, filter out, wash repeatedly with deionized water until the pH value reaches 6, dry and grind to obtain 3g of waste activated carbon powder, add 15g of 5wt% hydrochloric acid and mix evenly, heat to 30℃, reflux reaction for 1 hour, filter, wash repeatedly, and vacuum dry at 70℃ for 2 hours to obtain pretreated activated carbon;

[0046] S2: Mix 75g of anhydrous ethanol and 22.5g of deionized water evenly, adjust the pH value to 6, add 0.117g of nano-iron oxide, ultrasonically disperse for 15min, then add dropwise a mixture of 0.176g of tetraethyl orthosilicate and 3.52g of anhydrous ethanol, and add it dropwise over 1h. Stir evenly at 300r / min, separate and collect under magnetic field, wash multiple times, and then vacuum dry at 70℃ for 5h to obtain magnetic silica.

[0047] S3: Mix 1.5g chitosan and 105g of 1.5% (v / v) glacial acetic acid aqueous solution, ultrasonically disperse for 20min, add 0.12g magnetic silica, stir evenly at 250r / min, then add 0.75g ternary photocatalyst and mix evenly, then add 9g glutaraldehyde dropwise over 30min to obtain a sol; starting at 40℃, age the sol to 70℃ at a heating rate of 10℃ / d, keep it at that temperature for 1d, then soak it in anhydrous ethanol, shake and replace it twice at room temperature, then soak it in deionized water for 22h, changing the water every 3h during this period, and freeze-dry for 46h to obtain a composite aerogel; calcine the composite aerogel in a muffle furnace at a rate of 2℃ / min from room temperature to 450℃ for 2h, then cool it to room temperature to obtain a composite photocatalyst;

[0048] S4: Mix 1g of composite photocatalyst, 3g of pretreated activated carbon, and 50g of deionized water, sonicate for 30 minutes, stir evenly at 500r / min, and vacuum dry at 70℃ for 12h to obtain a mixture; calcine the mixture in a muffle furnace at a rate of 2℃ / min from room temperature to 500℃ for 2h, and cool to room temperature to obtain environmentally friendly regenerated activated carbon;

[0049] The preparation process of ternary photocatalysts is as follows:

[0050] Step (1): Mix 1g of melamine and 100g of deionized water, heat to 80℃, stir until completely dissolved, add dropwise a mixed solution of 1g of cyanuric acid and 100g of deionized water, add dropwise over 1 hour, evaporate the water and vacuum dry at 100℃ for 24 hours to obtain the precursor, calcine the precursor in a muffle furnace at a rate of 2℃ / min from room temperature to 500℃ for 3 hours to obtain porous carbon nitride;

[0051] Step (2): Mix 1g of cerium nitrate hexahydrate, 3.8g of potassium bromate, 1g of L-asparagine, and 1g of porous carbon nitride evenly, add 170g of deionized water, stir evenly, place in a 200mL polytetrafluoroethylene-lined reactor, keep warm at 140℃ for 22h, cool to room temperature, wash with anhydrous ethanol and deionized water alternately, and dry under vacuum at 70℃ for 10h to obtain the composite.

[0052] Step (3): Mix 1g of the complex with 30g of deionized water, sonicate for 50min, add a mixed solution of 1.5g of zinc nitrate hexahydrate and 35g of methanol, stir evenly, then add a mixed solution of 4g of 2-methylimidazole and 80g of methanol, stir evenly, centrifuge, wash repeatedly and dry to obtain the ternary photocatalyst.

[0053] Example 2: A method for preparing environmentally friendly recycled activated carbon, comprising the following processes:

[0054] S1: Soak the waste activated carbon in deionized water for 18 hours, heat to boiling for 15 minutes, filter out, wash repeatedly with deionized water until the pH value reaches 6.5, dry and grind to obtain 4g of waste activated carbon powder, add 24g of 8wt% hydrochloric acid and mix evenly, heat to 35℃, reflux reaction for 1.5 hours, filter, wash repeatedly, and vacuum dry at 75℃ for 3 hours to obtain pretreated activated carbon;

[0055] S2: Mix 75g of anhydrous ethanol and 24g of deionized water evenly, adjust the pH value to 6.5, add 0.13g of nano-iron oxide, ultrasonically disperse for 20min, then add dropwise a mixture of 0.23g of tetraethyl orthosilicate and 5.75g of anhydrous ethanol over 1.5h. Stir evenly at 350r / min, separate by magnetic field, collect, wash multiple times, and vacuum dry at 75℃ for 6h to obtain magnetic silica.

[0056] S3: Mix 1.5g chitosan and 110g of 1.8% glacial acetic acid aqueous solution, ultrasonically disperse for 25min, add magnetic silica, stir evenly at 300r / min, then add 0.8g ternary photocatalyst and mix evenly, then add 10.5g glutaraldehyde dropwise over 35min to obtain a sol; start at 45℃, age the sol to 75℃ at a heating rate of 15℃ / d, keep it at that temperature for 1.5d, then soak it in anhydrous ethanol, shake and replace it 3 times at room temperature, then soak it in deionized water for 23h, changing the water every 3h during this period, and freeze-dry for 47h to obtain a composite aerogel; calcine the composite aerogel in a muffle furnace at a rate of 4℃ / min from room temperature to 500℃ for 3h, then cool it to room temperature to obtain a composite photocatalyst;

[0057] S4: Mix 1g of composite photocatalyst, 4g of pretreated activated carbon, and 55g of deionized water, sonicate for 35min, stir evenly at 550r / min, and dry at 75℃ for 13h to obtain a mixture; calcine the mixture in a muffle furnace from room temperature to 530℃ at a rate of 4℃ / min for 3h, and cool to room temperature to obtain environmentally friendly regenerated activated carbon.

[0058] The preparation process of ternary photocatalysts is as follows:

[0059] Step (1): Mix 1g of melamine and 105g of deionized water, heat to 85℃, stir until completely dissolved, add dropwise a mixed solution of 1.2g of cyanuric acid and 126g of deionized water, add dropwise over 1.5h, evaporate the water and vacuum dry at 105℃ for 36h to obtain the precursor, calcine the precursor in a muffle furnace at a rate of 4℃ / min from room temperature to 540℃ for 3.5h to obtain porous carbon nitride;

[0060] Step (2): Mix 1g cerium nitrate hexahydrate, 3.9g potassium bromate, 1.1g L-asparagine, and 1.2g porous carbon nitride evenly, add 172g deionized water, stir evenly, place in a 200mL polytetrafluoroethylene-lined reactor, keep warm at 145℃ for 23h, cool to room temperature, wash with anhydrous ethanol and deionized water alternately, and dry under vacuum at 75℃ for 11h to obtain the composite.

[0061] Step (3): Mix 1g of the complex with 33g of deionized water, sonicate for 55min, add a mixed solution of 1.8g of zinc nitrate hexahydrate and 68g of methanol, stir evenly, then add a mixed solution of 4.5g of 2-methylimidazole and 112g of methanol, stir evenly, centrifuge, wash repeatedly and dry to obtain the ternary photocatalyst.

[0062] Example 3: A method for preparing environmentally friendly recycled activated carbon, comprising the following processes:

[0063] S1: Soak the waste activated carbon in deionized water for 24 hours, heat and boil for 20 minutes, filter out, wash repeatedly with deionized water until the pH value reaches 7, dry and grind to obtain 5g of waste activated carbon powder, add 35g of 10wt% hydrochloric acid and mix evenly, heat to 40℃, reflux reaction for 2 hours, filter, wash repeatedly, and vacuum dry at 80℃ for 4 hours to obtain pretreated activated carbon;

[0064] S2: Mix 100g of anhydrous ethanol and 35g of deionized water evenly, adjust the pH value to 7, add 0.2g of nano-iron oxide, ultrasonically disperse for 25min, then add 0.4g of a mixture of tetraethyl orthosilicate and anhydrous ethanol dropwise over 2h, stir evenly at 400r / min, separate by magnetic field, collect, wash multiple times, and vacuum dry at 80℃ for 7h to obtain magnetic silica;

[0065] S3: Mix 2g of chitosan and 150g of 2.0% glacial acetic acid aqueous solution, ultrasonically disperse for 30min, add 0.2g of magnetic silica, stir evenly at 350r / min, then add 1.2g of ternary photocatalyst and mix evenly. Add glutaraldehyde dropwise over 40min to obtain a sol. Start at 50℃ and age the sol to 80℃ at a heating rate of 20℃ / d. After holding at this temperature for 2d, soak in anhydrous ethanol, shake and replace 3 times at room temperature, then soak in deionized water for 24h, changing the water every 3h. After freeze-drying for 48h, obtain a composite aerogel. Heat the composite aerogel in a muffle furnace from room temperature to 550℃ at a rate of 5℃ / min, calcine for 4h, and cool to room temperature to obtain the composite photocatalyst.

[0066] S4: Mix 1g of composite photocatalyst, 5g of pretreated activated carbon, and 60g of deionized water, sonicate for 40min, stir evenly at 600r / min, and dry at 80℃ for 14h to obtain a mixture; calcine the mixture in a muffle furnace at a rate of 5℃ / min from room temperature to 550℃ for 4h, and cool to room temperature to obtain environmentally friendly regenerated activated carbon.

[0067] The preparation process of ternary photocatalysts is as follows:

[0068] Step (1): Mix 1g of melamine and 110g of deionized water, heat to 90℃, stir until completely dissolved, add dropwise a mixed solution of 1.5g of cyanuric acid and 165g of deionized water, add dropwise over 2 hours, evaporate the water and vacuum dry at 110℃ for 48 hours to obtain the precursor, calcine the precursor in a muffle furnace at a rate of 5℃ / min from room temperature to 550℃ for 4 hours to obtain porous carbon nitride;

[0069] Step (2): Mix 1g cerium nitrate hexahydrate, 4g potassium bromate, 1.2g L-asparagine, and 1.5g porous carbon nitride evenly, add 175g deionized water, stir evenly, place in a 200mL polytetrafluoroethylene-lined reactor, keep warm at 150℃ for 24h, cool to room temperature, wash with anhydrous ethanol and deionized water alternately, and dry under vacuum at 80℃ for 12h to obtain the composite.

[0070] Step (3): Mix 1g of the complex with 35g of deionized water, sonicate for 60min, add a mixed solution of 2g of zinc nitrate hexahydrate and 40g of methanol, stir evenly, then add a mixed solution of 5g of 2-methylimidazole and 150g of methanol, stir evenly, centrifuge, wash repeatedly and dry to obtain the ternary photocatalyst.

[0071] Comparative Example 1: A method for preparing environmentally friendly recycled activated carbon, comprising the following processes:

[0072] Compared with Example 1, Comparative Example 1 does not include S2, and replaces the magnetic silicon dioxide in S3 with the same mass of ordinary silicon dioxide (20nm, from Shanghai Naio Nanotechnology Co., Ltd.). Other steps and processes are the same as in Example 1.

[0073] Comparative Example 2: A method for preparing environmentally friendly recycled activated carbon, comprising the following processes:

[0074] S1: Soak the waste activated carbon in deionized water for 12 hours, heat to boiling for 10 minutes, filter out, wash repeatedly with deionized water until the pH value reaches 6, dry and grind to obtain 3g of waste activated carbon powder, add 15g of 5wt% hydrochloric acid and mix evenly, heat to 30℃, reflux reaction for 1 hour, filter, wash repeatedly, and vacuum dry at 70℃ for 2 hours to obtain pretreated activated carbon;

[0075] S2: Mix 1g of ternary photocatalyst, 3g of pretreated activated carbon, and 50g of deionized water, sonicate for 30min, stir evenly at 500r / min, and vacuum dry at 70℃ for 12h to obtain a mixture; calcine the mixture in a muffle furnace at a rate of 2℃ / min from room temperature to 500℃ for 2h, and cool to room temperature to obtain environmentally friendly regenerated activated carbon;

[0076] The preparation process of ternary photocatalysts is as follows:

[0077] Step (1): Mix 1g of melamine and 100g of deionized water, heat to 80℃, stir until completely dissolved, add dropwise a mixed solution of 1g of cyanuric acid and 100g of deionized water, add dropwise over 1 hour, evaporate the water and vacuum dry at 100℃ for 24 hours to obtain the precursor, calcine the precursor in a muffle furnace at a rate of 2℃ / min from room temperature to 500℃ for 3 hours to obtain porous carbon nitride;

[0078] Step (2): Mix 1g of cerium nitrate hexahydrate, 3.8g of potassium bromate, 1g of L-asparagine, and 1g of porous carbon nitride evenly, add 170g of deionized water, stir evenly, place in a 200mL polytetrafluoroethylene-lined reactor, keep warm at 140℃ for 22h, cool to room temperature, wash with anhydrous ethanol and deionized water alternately, and dry under vacuum at 70℃ for 10h to obtain the composite.

[0079] Step (3): Mix 1g of the complex with 30g of deionized water, sonicate for 50min, add a mixed solution of 1.5g of zinc nitrate hexahydrate and 35g of methanol, stir evenly, then add a mixed solution of 4g of 2-methylimidazole and 80g of methanol, stir evenly, centrifuge, wash repeatedly and dry to obtain a ternary photocatalyst.

[0080] Compared with Example 1, Comparative Example 2 does not include S2 and S3, and replaces the composite photocatalyst in S4 with a ternary photocatalyst. Other steps and processes are the same as in Example 1.

[0081] Comparative Example 3: A method for preparing environmentally friendly recycled activated carbon, comprising the following processes:

[0082] Compared with Example 2, Comparative Example 3 does not include the preparation process of the ternary photocatalyst. The ternary photocatalyst in S3 is replaced with titanium dioxide particles of the same mass (anatase type, particle size 5-15nm, sourced from Nanjing Baoket New Materials Co., Ltd.). Other steps are the same as in Example 2.

[0083] Comparative Example 4: A method for preparing environmentally friendly recycled activated carbon, comprising the following processes:

[0084] The preparation process of ternary photocatalysts is as follows:

[0085] Step (1): Mix 1g of melamine and 105g of deionized water, heat to 85℃, stir until completely dissolved, add dropwise a mixed solution of 1.2g of cyanuric acid and 126g of deionized water, add dropwise over 1.5h, evaporate the water and vacuum dry at 105℃ for 36h to obtain the precursor, calcine the precursor in a muffle furnace at a rate of 4℃ / min from room temperature to 540℃ for 3.5h to obtain porous carbon nitride;

[0086] Step (2): Mix 1g of cerium nitrate hexahydrate, 1g of potassium bromate, 0.5g of L-asparagine, and 0.5g of porous carbon nitride evenly, add 172g of deionized water, stir evenly, place in a 200mL polytetrafluoroethylene-lined reactor, keep warm at 145℃ for 23h, cool to room temperature, wash with anhydrous ethanol and deionized water alternately, and dry under vacuum at 75℃ for 11h to obtain the composite.

[0087] Step (3): Mix 1g of the complex with 33g of deionized water, sonicate for 55min, add a mixed solution of 1.8g of zinc nitrate hexahydrate and 68g of methanol, stir evenly, then add a mixed solution of 4.5g of 2-methylimidazole and 112g of methanol, stir evenly, centrifuge, wash repeatedly and dry to obtain the ternary photocatalyst.

[0088] Compared with Example 2, in step (2) of Comparative Example 4, the mass ratio of cerium nitrate hexahydrate, potassium bromate, L-asparagine, and porous carbon nitride is 1:1:0.5:0.5, and the remaining steps are the same as in Example 2.

[0089] experiment

[0090] The environmentally friendly recycled activated carbon obtained in Examples 1-3 and Comparative Examples 1-4 was used to prepare samples, and its performance was tested and the test results were recorded:

[0091] The photocatalytic performance of RhB (Rhodamine B) under simulated sunlight degradation was studied. The experimental procedure was as follows: 0.1 g of environmentally friendly regenerated activated carbon was added to a 50 mg / L RhB solution (total volume 100 mL), and the solution was stirred in the dark for 60 min to reach adsorption equilibrium. A 300 W xenon lamp was used as the light source for 120 min. During the illumination period, 5 mL of RhB solution was collected and centrifuged at 40 min, 80 min, and 120 min. The absorbance A of the supernatant at 552 nm was measured using a UV-Vis spectrophotometer, and the degradation rate X was calculated using the following formula: X = (A0 - A...) / (A0 - A0 ... t ) / A0×100%, where A0 is the initial absorbance, A t t represents the absorbance at reaction time t.

[0092] The specific surface area was determined by nitrogen adsorption-desorption (BET method). The experimental procedure was as follows: 2g of the environmentally friendly recycled activated carbon sample to be tested was weighed and dried at 120℃. The dried sample was then analyzed using a nitrogen adsorption instrument.

[0093] Test Results

[0094]

[0095]

[0096] Based on the data in the table above, the following conclusions can be clearly drawn:

[0097] 1. Compared with examples 1-3, the degradation rate and specific surface area of ​​the products obtained in Comparative Examples 1 and 2 both decreased, indicating that the magnetic silica of the present invention has better magnetic properties and adsorption capacity than ordinary silica; the composite photocatalyst has better catalytic effect than the ternary photocatalyst, which further proves that the three-dimensional network structure constructed in this invention is beneficial to photocatalytic reactions. Through this three-dimensional network structure, the light absorption capacity of the photocatalyst is enhanced, and reactant molecules can more easily contact the active sites, thereby improving the reaction rate and efficiency.

[0098] 2. Compared with Examples 1-3, the degradation rate and specific surface area of ​​the product obtained in Comparative Example 3 both decreased, indicating that the ternary photocatalyst prepared by the present invention has better catalytic effect and larger specific surface area than titanium dioxide particles, and can provide more active sites, thereby enhancing the adsorption capacity and reaction efficiency of the photocatalyst.

[0099] 3. Compared with Examples 1-3, the degradation rate and specific surface area of ​​the product obtained in Comparative Example 4 have decreased. It can be seen that the performance of the ternary photocatalyst prepared by the present invention is affected by the ratio of each reagent in its preparation process. By selecting the mass ratio within the range described above, the prepared material has excellent photocatalytic performance and specific surface area.

[0100] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process method article or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process method article or apparatus.

[0101] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing environmentally friendly recycled activated carbon, characterized in that: Includes the following steps: S1: Soak waste activated carbon in deionized water for 12-24 hours, heat to boiling for 10-20 minutes, filter out, wash repeatedly with deionized water until the pH value reaches 6-7, then dry and grind to obtain waste activated carbon powder, add hydrochloric acid and mix evenly, heat to 30-40℃, reflux reaction for 1-2 hours, filter, wash repeatedly, and vacuum dry at 70-80℃ for 2-4 hours to obtain pretreated activated carbon; S2: Mix anhydrous ethanol and deionized water evenly, adjust the pH value to 6-7, add nano-iron oxide, ultrasonically disperse for 15-25 min, then add a mixture of tetraethyl orthosilicate and anhydrous ethanol dropwise over 1-2 h, stir evenly at 300-400 r / min, separate and collect under magnetic field, wash multiple times, and vacuum dry at 70-80℃ for 5-7 h to obtain magnetic silica; S3: Mix chitosan and glacial acetic acid aqueous solution, ultrasonically disperse for 20-30 min, add magnetic silica, stir evenly at 250-350 r / min, then add ternary photocatalyst and mix evenly, add glutaraldehyde dropwise over 30-40 min to obtain a sol; start at 40-50℃, age the sol to 70-80℃ at a heating rate of 10-20℃ / d, keep it at this temperature for 1-2 days, then soak it in anhydrous ethanol, shake and replace it 2-3 times at room temperature, then soak it in deionized water for 22-24 h, changing the water every 3 h during this period, and freeze-dry for 46-48 h to obtain a composite aerogel; heat the composite aerogel in a muffle furnace from room temperature to 450-550℃ at a rate of 2-5℃ / min, calcine for 2-4 h, and cool to room temperature to obtain a composite photocatalyst; S4: Mix the composite photocatalyst, pretreated activated carbon, and deionized water, ultrasonically disperse for 30-40 min, stir evenly at 500-600 r / min, and vacuum dry at 70-80℃ for 12-14 h to obtain a mixture; calcine the mixture in a muffle furnace at a rate of 2-5℃ / min from room temperature to 500-550℃ for 2-4 h, and cool to room temperature to obtain environmentally friendly regenerated activated carbon; The preparation method of the ternary photocatalyst in S3 is as follows: Step (1): Mix melamine and deionized water, heat to 80-90℃, stir until completely dissolved, add a mixed solution of cyanuric acid and deionized water dropwise over 1-2 hours, evaporate the water and vacuum dry at 100-110℃ for 24-48 hours to obtain a precursor, calcine the precursor in a muffle furnace at a rate of 2-5℃ / min from room temperature to 500-550℃ for 3-4 hours to obtain porous carbon nitride; Step (2): Cerium nitrate hexahydrate, potassium bromate, L-asparagine, and porous carbon nitride are mixed evenly, deionized water is added, and the mixture is stirred evenly. The mixture is placed in a 200 mL polytetrafluoroethylene-lined reactor and kept at 140-150 °C for 22-24 h. After cooling to room temperature, the mixture is washed alternately with anhydrous ethanol and deionized water, and then vacuum dried at 70-80 °C for 10-12 h to obtain the composite. Step (3): Mix the complex with deionized water, sonicate for 50-60 min, add a mixed solution of zinc nitrate hexahydrate and methanol, stir evenly, then add a mixed solution of 2-methylimidazole and methanol, stir evenly, and after centrifugation, multiple washings and drying, the ternary photocatalyst is obtained.

2. The method for preparing environmentally friendly recycled activated carbon according to claim 1, characterized in that: The mass ratio of waste activated carbon powder to hydrochloric acid in S1 is 1:(5-7).

3. The method for preparing environmentally friendly recycled activated carbon according to claim 1, characterized in that: The mass ratio of nano-iron oxide and tetraethyl orthosilicate in S2 is 1:(1.5-2.0).

4. The method for preparing environmentally friendly recycled activated carbon according to claim 1, characterized in that: The mass of magnetic silica in S3 is 8-10% of the mass of chitosan.

5. The method for preparing environmentally friendly recycled activated carbon according to claim 1, characterized in that: In step (1), the mass ratio of cyanuric acid to melamine is 1:(1.0-1.5), and the mass ratio of cyanuric acid to deionized water is 1:(100-110).

6. The method for preparing environmentally friendly recycled activated carbon according to claim 1, characterized in that: In step (2), the mass ratio of cerium nitrate hexahydrate, potassium bromate, L-asparagine, and porous carbon nitride is 1:(3.8-4.0):(1.0-1.2):(1.0-1.5).

7. The method for preparing environmentally friendly recycled activated carbon according to claim 1, characterized in that: In step (3), the mass of zinc nitrate hexahydrate is 1.5-2.0 times the mass of the complex, and the mass ratio of zinc nitrate hexahydrate to methanol is 1:(35-40).

8. The method for preparing environmentally friendly recycled activated carbon according to claim 1, characterized in that, The mass ratio of the composite photocatalyst, pretreated activated carbon, and deionized water in S4 is 1:(2-3):(50-60).

9. An environmentally friendly regenerated activated carbon prepared by the preparation method according to any one of claims 1-8.

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