Preparation method of potassium-calcium-iron three-metal doped magnetic porous carbon based on total solid waste

Abstract

The application discloses a preparation method of a potassium-calcium-iron three-metal doped magnetic porous carbon based on a full solid waste, and belongs to the technical field of solid waste resource utilization and environmental protection. In-situ activation of calcium carbonate, calcium oxide and trace potassium oxide in lime dusting ash is utilized, and the doping effect of iron oxides in iron-containing dusting ash is combined, so that a hierarchical pore structure is constructed without adding calcium salt or iron salt, and the preparation cost is significantly reduced. Through the synergistic effect of hydrothermal carbonization and pyrolysis activation, uniform distribution of potassium, calcium and iron components in the carbon matrix is realized, which is beneficial to improving the structural stability and surface activity of the material. The pH adjustment effect of calcium oxide and trace potassium oxide in lime dusting ash and the magnetic iron oxide generated through hydrothermal carbonization and pyrolysis activation of iron oxides in iron-containing dusting ash improve the adsorption capacity of the material and make it easy to separate and recover.

Description

Technical Field

[0001] This invention belongs to the field of solid waste resource utilization and environmental protection technology, and in particular relates to a method for preparing potassium-calcium-iron trimetallic doped magnetic porous carbon based on all solid waste. Background Technology

[0002] Furfural residue is an organic solid waste generated during the furfural production process from biomass such as corn cobs and straw. It contains a large amount of cellulose and hemicellulose degradation products and residual lignin, and has a high carbon content, with an annual output exceeding one million tons. It can serve as an excellent carbon precursor material. However, long-term storage of furfural residue easily generates leachate, polluting soil and water bodies. Therefore, the material utilization of furfural residue is of great significance in environmental protection and resource recycling.

[0003] Iron-containing dust, derived from sintering dust and blast furnace gas ash generated during steel production, is typically rich in iron oxides and is a typical iron-based industrial solid waste. Improper disposal can pollute soil and water. Due to its high iron content, it has potential for recycling in the metallurgical field. Lime dust, mainly a byproduct of lime kiln production, comprises lime, gypsum, silicates, and other metal oxides, exhibiting strong alkalinity and potential activation capabilities. Recycling lime dust can not only reduce environmental burden but also provide a source of raw materials for industrial production. Therefore, utilizing iron-containing dust and lime dust to prepare functional materials offers both economic and environmental benefits.

[0004] Most existing porous carbon materials are prepared by adding chemical reagents to achieve activation and doping, which not only increases the preparation cost but also poses problems such as heavy post-processing burden and secondary pollution risk. On the other hand, there is little research on the synergistic material utilization of three types of solid waste: furfural residue, iron-containing dust, and lime dust. There is a lack of porous carbon preparation technologies that utilize calcium carbonate, calcium oxide, and potassium oxide in lime dust as sources for pH adjustment, in-situ activation, and doping.

[0005] Therefore, developing a method for preparing magnetic porous carbon doped with potassium, calcium, and iron using furfural residue, iron-containing dust, and lime dust as raw materials is of great significance for improving the level of solid waste resource utilization. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention proposes a method for preparing potassium-calcium-iron trimetallic doped magnetic porous carbon based on solid waste. This invention uses furfural residue, iron-containing dust (selected from blast furnace gas ash), and lime dust (selected from the finished product section of a lime kiln) as raw materials. Through hydrothermal carbonization and pyrolysis activation, it achieves the simultaneous construction of potassium, calcium, and iron trimetallic doping and a hierarchical porous structure. The method provided by this invention is simple, environmentally friendly, and enables the resource utilization of various solid wastes, generating economic benefits and promoting green and sustainable development.

[0007] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a method for preparing potassium-calcium-iron trimetallic doped magnetic porous carbon based on all solid waste, comprising the following steps: Furfural residue, iron-containing dust removal ash, and lime dust removal ash are mixed and then water is added to obtain a mixed slurry. The mixed slurry is then subjected to hydrothermal carbonization and pyrolysis activation in sequence to obtain the potassium-calcium-iron trimetallic doped magnetic porous carbon.

[0008] Furthermore, the mass ratio of furfural residue, iron-containing dust removal ash, and lime dust removal ash is (2~8):(1~6):(1~3).

[0009] Furthermore, the particle size of the furfural residue, iron-containing dust, and lime dust is 80-100 mesh.

[0010] Furthermore, the solid-liquid mass ratio of the mixed slurry is 1:(5~10).

[0011] Furthermore, the hydrothermal carbonization temperature is 200~280℃, and the hydrothermal carbonization time is 1~4h.

[0012] Furthermore, the hydrothermal carbonization is carried out under closed and stirred conditions; the stirring rate is 200~300 r / min.

[0013] Furthermore, the pyrolysis activation temperature is 600~800℃, the pyrolysis activation holding time is 1~3h, the pyrolysis activation heating rate is 5~15℃ / min, and the pyrolysis activation atmosphere is a protective atmosphere.

[0014] Furthermore, the pyrolysis activation process also includes washing and drying steps; the washing reagents are deionized water and acid solution; the concentration of the acid solution is 0.1~1 mol / L, and the acid solution is selected from hydrochloric acid, nitric acid or acetic acid.

[0015] The present invention also provides a potassium-calcium-iron trimetallic doped magnetic porous carbon, which is prepared according to the preparation method described in the above technical solution.

[0016] Furthermore, the potassium-calcium-iron trimetallic doped magnetic porous carbon has a microporous-mesoporous hierarchical pore structure.

[0017] The present invention also provides an application of the potassium-calcium-iron trimetallic doped magnetic porous carbon described in the above technical solution in the adsorption and catalytic degradation of tetracycline hydrochloride.

[0018] Compared with the prior art, the present invention has the following advantages and technical effects: This invention uses furfural residue as a carbon source and a reducing agent to promote the formation of magnetic iron oxides, iron-containing dust as a magnetic iron source, and lime dust as a potassium and calcium source, pH adjuster, and activator. Through hydrothermal carbonization and pyrolysis activation, potassium, calcium, and iron trimetallic doping and hierarchical porous structure are simultaneously constructed, resulting in potassium-calcium-iron trimetallic doped magnetic porous carbon with hierarchical porous structure and strong magnetism. The optimal porous carbon exhibits an iron doping content of 21%, a calcium doping content of 7%, and a potassium doping content of 4%, with a specific surface area of ​​942.5 m². 2 / g.

[0019] This invention utilizes furfural residue, iron-containing dust, and lime dust as raw materials to achieve a synergistic supply of carbon, iron, calcium, and potassium sources, and to prepare trimetallic-doped magnetic porous carbon from all solid waste. By leveraging the in-situ activation capabilities of calcium carbonate, calcium oxide, and trace amounts of potassium oxide in the lime dust, combined with the doping effect of iron oxides in the iron-containing dust, a hierarchical porous structure is constructed without the addition of calcium or iron salts, significantly reducing preparation costs. Through the synergistic effect of hydrothermal carbonization and pyrolysis activation, a uniform distribution of potassium, calcium, and iron components in the carbon matrix is ​​achieved, which is beneficial for improving the structural stability and surface activity of the material. The pH-regulating effect of calcium oxide and trace amounts of potassium oxide in the lime dust, and the magnetic iron oxides generated from the hydrothermal carbonization and pyrolysis activation of iron oxides in the iron-containing dust, enhance the material's adsorption capacity while facilitating its separation and recovery. In the application of potassium-calcium-iron trimetallic doped magnetic porous carbon for the adsorption and catalytic degradation of tetracycline hydrochloride, after an initial adsorption process of 30 min, the initial concentration of tetracycline hydrochloride decreased from 30 mg / L to 1.79 mg / L, and the maximum adsorption capacity of tetracycline hydrochloride was 94 mg / g, with a maximum adsorption rate of 94%. This indicates that the potassium-calcium-iron trimetallic doped magnetic porous carbon improved the adsorption capacity of the material. After a catalytic degradation process of 60 min, the concentration of tetracycline hydrochloride decreased to 0.25 mg / L, and the overall removal rate of tetracycline hydrochloride reached 99%.

[0020] The method provided by this invention is simple and environmentally friendly. The raw materials used are all solid wastes and are widely available. It realizes the resource utilization of various solid wastes, can create economic benefits, promote green and sustainable development, is suitable for large-scale production and application, and has good application prospects in the field of environmental remediation. Attached Figure Description

[0021] The accompanying drawings, which constitute a part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a process flow diagram of the preparation method of potassium-calcium-iron trimetallic doped magnetic porous carbon based on all solid waste in Examples 1-4 of the present invention; Figure 2 This explains the working principle of furfural residue, iron-containing dust removal ash, and lime dust removal ash in this invention; Figure 3 The image shows the XRD pattern of the iron-containing dust used in the embodiments of the present invention. Figure 4 The image shows the XRD pattern of the lime dust used in the embodiments of the present invention. Figure 5 The hysteresis loop diagrams are for the potassium-calcium-iron trimetallic doped magnetic porous carbons prepared in Examples 1-2, where FR2-Fe6-Ca2 is Example 1 and FR3-Fe4-Ca3 is Example 2. Figure 6 The image shows a physical sample of the potassium-calcium-iron trimetallic doped magnetic porous carbon prepared in Example 2. Figure 7 SEM images of potassium-calcium-iron trimetallic doped magnetic porous carbon prepared in Examples 1 and 4, and a mapping image of porous carbon prepared in Example 4, wherein FR2-Fe6-Ca2 is Example 1 and FR8-Fe1-Ca1 is Example 4; Figure 8 The BET diagrams are for potassium-calcium-iron trimetallic doped magnetic porous carbons prepared in Examples 3 and 4, where FR7-Fe2-Ca1 is Example 3 and FR8-Fe1-Ca1 is Example 4. Figure 9 The graphs show the removal rates of tetracycline hydrochloride by adsorption and catalytic degradation of potassium-calcium-iron trimetallic doped magnetic porous carbon prepared in Examples 3 and 4, where FR7-Fe2-Ca1 is Example 3 and FR8-Fe1-Ca1 is Example 4. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.

[0023] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] This invention provides a method for preparing potassium-calcium-iron trimetallic doped magnetic porous carbon based on all solid waste, comprising the following steps: Furfural residue, iron-containing dust removal ash, and lime dust removal ash are mixed and then water is added to obtain a mixed slurry. The mixed slurry is then subjected to hydrothermal carbonization and pyrolysis activation in sequence to obtain the potassium-calcium-iron trimetallic doped magnetic porous carbon.

[0025] In a preferred embodiment, the mass ratio of furfural residue, iron-containing dust, and lime dust is (2~8):(1~6):(1~3). In this invention, furfural residue serves as a carbon source and reducing agent, iron-containing dust serves as an iron dopant source, in-situ activation source, and magnetic modifier, and lime dust serves as a calcium-potassium dopant source, in-situ activation source, and pH adjuster.

[0026] The working principle of furfural residue, iron-containing dust removal ash, and lime dust removal ash in this invention is as follows: Figure 2 It can be seen that furfural residue is used as a reducing agent, lime dust is used as an activator and regulator, and iron-containing dust is used as a magnetic modifier. After hydrothermal carbonization and pyrolysis activation, potassium-calcium-iron trimetallic doped magnetic porous carbon with strong magnetic properties was obtained.

[0027] In a preferred embodiment, the furfural residue, iron-containing dust, and lime dust are pretreated before use; the pretreatment includes drying, crushing, and sieving; the drying temperature is 80~105℃, and the drying time is 24h; the sieving is through an 80~100 mesh sieve.

[0028] In a preferred embodiment, the particle size of the furfural residue, iron-containing dust, and lime dust is 80-100 mesh.

[0029] In a preferred embodiment, the solid-liquid mass ratio of the mixed slurry is 1:(5~10), and more preferably 1:10.

[0030] In a preferred embodiment, the process after adding water further includes a stirring step; the stirring rate is 200~300 r / min, and the stirring time is 60 min.

[0031] In a preferred embodiment, the hydrothermal carbonization temperature is 200~280℃, more preferably 280℃; the hydrothermal carbonization time is 1~4h, more preferably 1h. During the hydrothermal carbonization process, furfural residue undergoes hydrothermal carbonization to form hydrothermal carbon rich in oxygen-containing functional groups; under the condition that lime dust provides calcium oxide and trace potassium oxide as pH adjusters, iron oxides in iron-containing dust generate a certain amount of magnetic iron oxides in the hydrothermal environment and are fixed on the surface of the hydrothermal carbon; calcium oxide and trace potassium oxide in lime dust react with water to generate calcium hydroxide and trace potassium hydroxide, which migrate to the surface of the hydrothermal carbon while regulating the hydrothermal carbonization of furfural residue and iron-containing dust, thereby constructing magnetic hydrothermal carbon containing potassium, calcium and iron components.

[0032] In a preferred embodiment, the hydrothermal carbonization is carried out under closed and stirred conditions; the stirring rate is 200-300 r / min, more preferably 200 r / min. This invention promotes the migration and uniform distribution of potassium, calcium, and iron components in iron-containing dust and lime dust into the hydrothermal carbon through stirring, while simultaneously promoting the further conversion of iron oxides into magnetic iron oxides.

[0033] In a preferred embodiment, the process after hydrothermal carbonization includes filtration, washing, and drying. The filtration device is a vacuum pump. The washing reagent is deionized water, and the washing is performed three times. The drying temperature is 80-105°C, more preferably 90°C, and the drying time is 24 hours.

[0034] In a preferred embodiment, the pyrolysis activation temperature is 600~800℃, more preferably 800℃; the holding time for pyrolysis activation is 1~3h, more preferably 1h; the heating rate for pyrolysis activation is 5~15℃ / min, more preferably 10℃ / min; and the atmosphere for pyrolysis activation is a protective atmosphere, which is nitrogen or argon. During the pyrolysis activation process, calcium carbonate and calcium hydroxide in the lime dust decompose and undergo a solid-phase reaction with the carbon skeleton, producing an in-situ activation effect on the carbon material. Trace amounts of potassium components produce a synergistic activation effect on the carbon skeleton under high-temperature conditions. Iron oxides in the iron-containing dust undergo a reduction reaction under high-temperature conditions to generate a large amount of magnetic iron oxides, forming stable and dispersed iron-based active sites in the carbon matrix, thereby achieving potassium, calcium, and iron trimetallic doping while constructing a hierarchical porous structure.

[0035] In a preferred embodiment, the pyrolysis activation process further includes washing and drying steps; the washing reagent is deionized water and an acid solution; the concentration of the acid solution is 0.1~1 mol / L, and the acid solution is selected from hydrochloric acid, nitric acid, or acetic acid; the drying temperature is 90°C, and the drying time is 24 h.

[0036] The present invention also provides a potassium-calcium-iron trimetallic doped magnetic porous carbon, which is prepared according to the preparation method described in the above technical solution.

[0037] In a preferred embodiment, the potassium-calcium-iron trimetallic doped magnetic porous carbon has a hierarchical pore structure of micropores and mesopores. The pore structure of the potassium-calcium-iron trimetallic doped magnetic porous carbon in this invention is jointly constructed by calcium carbonate, calcium oxide, and trace amounts of potassium oxide in lime dust, and magnetic iron oxides in iron-containing dust during the in-situ activation process. Its strong magnetism originates from the gradual formation of magnetic iron oxides during hydrothermal carbonization and pyrolysis activation.

[0038] In this embodiment of the invention, room temperature refers to "25±2℃".

[0039] The industrial and elemental analyses of the furfural residue used in the embodiments of the present invention are shown in Table 1, the main component analyses of the iron-containing dust removal ash are shown in Table 2, the main component analyses of the lime dust removal ash are shown in Table 3, the main metal component analyses of the FR7-Fe2-Ca1 porous carbon prepared in Example 3 are shown in Table 4, and the structural parameters of the porous carbon pores prepared in Examples 3-4 are shown in Table 5.

[0040] Table 1 Table 2 Table 3 Table 4 Table 5 The XRD pattern of the iron-containing dust used in the embodiments of the present invention is shown in the figure. Figure 3 It can be seen that the main component of iron-containing dust is non-magnetic ferric oxide.

[0041] The XRD pattern of the lime dust used in this embodiment of the invention is shown in the figure. Figure 4 As can be seen, the main components of lime dust are calcium carbonate and calcium oxide.

[0042] Example 1 A method for preparing potassium-calcium-iron trimetallic doped magnetic porous carbon based on all solid waste, the process flow is as follows: Figure 1 The steps are as follows: Take 2g of furfural residue, 6g of iron-containing dust removal ash, and 2g of lime dust removal ash (i.e., the mass ratio of furfural residue, iron-containing dust removal ash, and lime dust removal ash is 2:6:2), dry them separately in an oven at 105℃ for 24h, pulverize them thoroughly, and pass them through an 80-mesh sieve to obtain powder with a particle size of less than 0.18mm. Mix the three powders and add 100mL of deionized water (i.e., the solid-liquid mass ratio of the mixed slurry is 1:10), and stir at a rate of 200r / min for 60min to obtain the mixed slurry. The resulting mixed slurry was transferred to a closed high-temperature and high-pressure reactor and hydrothermally carbonized for 1 hour at a constant temperature of 280℃ and a stirring rate of 200 r / min. After the reaction was completed, the mixture was cooled to room temperature, filtered by vacuum pump, washed three times with deionized water, and then dried in an oven at 90℃ for 24 hours to obtain hydrothermal carbon. The obtained hydrothermal carbon was placed in a tube furnace and heated to 800℃ at a heating rate of 10℃ / min under nitrogen atmosphere protection. The temperature was then maintained for 1 hour. After the reaction was completed and cooled to room temperature, the carbon was washed with 1 mol / L hydrochloric acid and deionized water until neutral. It was then dried in an oven at 90℃ for 24 hours to obtain potassium-calcium-iron trimetallic doped magnetic porous carbon (denoted as FR2-Fe6-Ca2).

[0043] Example 2 A method for preparing potassium-calcium-iron trimetallic doped magnetic porous carbon based on all solid waste, the process flow is as follows: Figure 1 The steps are as follows: Take 3g of furfural residue, 4g of iron-containing dust removal ash, and 3g of lime dust removal ash (i.e., the mass ratio of furfural residue, iron-containing dust removal ash, and lime dust removal ash is 3:4:3), dry them separately in an oven at 105℃ for 24h, pulverize them thoroughly, and pass them through an 80-mesh sieve to obtain powder with a particle size of less than 0.18mm. Mix the three powders and add 100mL of deionized water (i.e., the solid-liquid mass ratio of the mixed slurry is 1:10), and stir at a rate of 200r / min for 60min to obtain the mixed slurry. The resulting mixed slurry was transferred to a closed high-temperature and high-pressure reactor and hydrothermally carbonized for 1 hour at a constant temperature of 280℃ and a stirring rate of 200 r / min. After the reaction was completed, the mixture was cooled to room temperature, filtered by vacuum pump, washed three times with deionized water, and then dried in an oven at 90℃ for 24 hours to obtain hydrothermal carbon. The obtained hydrothermal carbon was placed in a tube furnace and heated to 800℃ at a heating rate of 10℃ / min under nitrogen atmosphere protection. The temperature was then maintained for 1 hour. After the reaction was completed and cooled to room temperature, the carbon was washed with 1 mol / L hydrochloric acid and deionized water until neutral. It was then dried in an oven at 90℃ for 24 hours to obtain potassium-calcium-iron trimetallic doped magnetic porous carbon (denoted as FR3-Fe4-Ca3).

[0044] Example 3 A method for preparing potassium-calcium-iron trimetallic doped magnetic porous carbon based on all solid waste, the process flow is as follows: Figure 1 The steps are as follows: Take 7g of furfural residue, 2g of iron-containing dust removal ash, and 1g of lime dust removal ash (i.e., the mass ratio of furfural residue, iron-containing dust removal ash, and lime dust removal ash is 7:2:1), dry them separately in an oven at 105℃ for 24h, pulverize them thoroughly, and pass them through an 80-mesh sieve to obtain powder with a particle size of less than 0.18mm. Mix the three powders and add 100mL of deionized water (i.e., the solid-liquid mass ratio of the mixed slurry is 1:10), and stir at a rate of 200r / min for 60min to obtain the mixed slurry. The resulting mixed slurry was transferred to a closed high-temperature and high-pressure reactor and hydrothermally carbonized for 1 hour at a constant temperature of 280℃ and a stirring rate of 200 r / min. After the reaction was completed, the mixture was cooled to room temperature, filtered by vacuum pump, washed three times with deionized water, and then dried in an oven at 90℃ for 24 hours to obtain hydrothermal carbon. The obtained hydrothermal carbon was placed in a tube furnace and heated to 800℃ at a heating rate of 10℃ / min under nitrogen atmosphere protection. The temperature was then maintained for 1 hour. After the reaction was completed and cooled to room temperature, the carbon was washed with 1 mol / L hydrochloric acid and deionized water until neutral. It was then dried in an oven at 90℃ for 24 hours to obtain potassium-calcium-iron trimetallic doped magnetic porous carbon (denoted as FR7-Fe2-Ca1).

[0045] Example 4 A method for preparing potassium-calcium-iron trimetallic doped magnetic porous carbon based on all solid waste, the process flow is as follows: Figure 1 The steps are as follows: Take 8g of furfural residue, 1g of iron-containing dust removal ash, and 1g of lime dust removal ash (i.e., the mass ratio of furfural residue, iron-containing dust removal ash, and lime dust removal ash is 8:1:1), dry them separately in an oven at 105℃ for 24h, pulverize them thoroughly, and pass them through an 80-mesh sieve to obtain powder with a particle size of less than 0.18mm. Mix the three powders and add 100mL of deionized water (i.e., the solid-liquid mass ratio of the mixed slurry is 1:10). Stir at a rate of 200r / min for 60min to obtain the mixed slurry. The resulting mixed slurry was transferred to a closed high-temperature and high-pressure reactor and hydrothermally carbonized for 1 hour at a constant temperature of 280℃ and a stirring rate of 200 r / min. After the reaction was completed, the mixture was cooled to room temperature, filtered by vacuum pump, washed three times with deionized water, and then dried in an oven at 90℃ for 24 hours to obtain hydrothermal carbon. The obtained hydrothermal carbon was placed in a tube furnace and heated to 800℃ at a heating rate of 10℃ / min under nitrogen atmosphere protection. The temperature was then maintained for 1 hour. After the reaction was completed and cooled to room temperature, the carbon was washed with 1 mol / L hydrochloric acid and deionized water until neutral. It was then dried in an oven at 90℃ for 24 hours to obtain potassium-calcium-iron trimetallic doped magnetic porous carbon (denoted as FR8-Fe1-Ca1).

[0046] Figure 5 The figures show the hysteresis loops of the potassium-calcium-iron trimetallic doped magnetic porous carbons prepared in Examples 1-2, where FR2-Fe6-Ca2 is Example 1 and FR3-Fe4-Ca3 is Example 2. It can be seen that the potassium-calcium-iron trimetallic doped magnetic porous carbons obtained in Examples 1-2 exhibit good magnetic properties. When the mass ratio of furfural residue, iron-containing dust, and lime dust is 2:6:2, the saturation magnetization of the obtained potassium-calcium-iron trimetallic doped magnetic porous carbon reaches 39.10 emu / g. When the mass ratio of furfural residue, iron-containing dust, and lime dust is 3:4:3, the saturation magnetization of the obtained potassium-calcium-iron trimetallic doped magnetic porous carbon reaches 43.07 emu / g. This indicates that appropriately increasing the amount of furfural residue and lime dust is beneficial for obtaining porous carbon with excellent magnetic properties.

[0047] Figure 6 The image shows a physical picture of the potassium-calcium-iron trimetallic doped magnetic porous carbon prepared in Example 2. It can be seen that the porous carbon has good magnetic properties and is easy to separate from other substances by means of magnetic properties.

[0048] Figure 7 SEM images of potassium-calcium-iron trimetallic doped magnetic porous carbons prepared in Examples 1 and 4, and a mapping image of the porous carbon prepared in Example 4, where FR2-Fe6-Ca2 is from Example 1 and FR8-Fe1-Ca1 is from Example 4. As can be seen from the images, a good pore structure was generated after high-temperature activation, and the potassium, calcium, and iron trimetallic compounds were uniformly distributed on the surface of the porous carbon.

[0049] Figure 8 The figures show the BET curves of the potassium-calcium-iron trimetallic doped magnetic porous carbons prepared in Examples 3 and 4, where FR7-Fe2-Ca1 represents Example 3 and FR8-Fe1-Ca1 represents Example 4. As can be seen from the figures, the adsorption-desorption curves of the potassium-calcium-iron trimetallic doped magnetic porous carbons prepared in Examples 3 and 4 exhibit a combination of Type I and Type IV adsorption isotherms, and also possess an H4-type hysteresis loop. The pore size is concentrated in the range below 2 nm, indicating that the prepared porous carbons are predominantly microporous with some mesopores, making them carbon materials with a micro-mesoporous hierarchical pore structure.

[0050] Figure 9The graphs show the removal rates of tetracycline hydrochloride by the potassium-calcium-iron trimetallic doped magnetic porous carbon prepared in Examples 3 and 4, where FR7-Fe2-Ca1 represents Example 3 and FR8-Fe1-Ca1 represents Example 4. The graphs show that the adsorption rate of tetracycline hydrochloride reached over 60% within 30 minutes (60.20% in Example 3 and 94.04% in Example 4), and the removal rate reached over 85% after 60 minutes of catalytic degradation (88.16% in Example 3 and 99.18% in Example 4), demonstrating that the prepared material has good adsorption and catalytic performance. The experimental parameters were: initial tetracycline hydrochloride concentration: 30 mg / L; catalyst dosage: 0.3 g / L; PMS dosage: 3 mM; pH=6; shaking speed: 200 rpm; temperature: 25℃.

[0051] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing potassium-calcium-iron trimetallic doped magnetic porous carbon based on all solid waste, characterized in that, Includes the following steps: Furfural residue, iron-containing dust removal ash, and lime dust removal ash are mixed and then water is added to obtain a mixed slurry. The mixed slurry is then subjected to hydrothermal carbonization and pyrolysis activation in sequence to obtain the potassium-calcium-iron trimetallic doped magnetic porous carbon.

2. The method for preparing potassium-calcium-iron trimetallic doped magnetic porous carbon based on all solid waste according to claim 1, characterized in that, The mass ratio of furfural residue, iron-containing dust removal ash and lime dust removal ash is (2~8):(1~6):(1~3).

3. The method for preparing potassium-calcium-iron trimetallic doped magnetic porous carbon based on all solid waste according to claim 2, characterized in that, The particle size of the furfural residue, iron-containing dust, and lime dust is 80-100 mesh.

4. The method for preparing potassium-calcium-iron trimetallic doped magnetic porous carbon based on all solid waste according to claim 1, characterized in that, The solid-liquid mass ratio of the mixed slurry is 1:(5~10).

5. The method for preparing potassium-calcium-iron trimetallic doped magnetic porous carbon based on all solid waste according to claim 1, characterized in that, The hydrothermal carbonization temperature is 200~280℃, and the hydrothermal carbonization time is 1~4h.

6. The method for preparing potassium-calcium-iron trimetallic doped magnetic porous carbon based on all solid waste according to claim 5, characterized in that, The hydrothermal carbonization is carried out under closed and stirred conditions; the stirring rate is 200~300 r / min.

7. The method for preparing potassium-calcium-iron trimetallic doped magnetic porous carbon based on all solid waste according to claim 1, characterized in that, The pyrolysis activation temperature is 600~800℃, the holding time for pyrolysis activation is 1~3h, the heating rate for pyrolysis activation is 5~15℃ / min, and the atmosphere for pyrolysis activation is a protective atmosphere.

8. The method for preparing potassium-calcium-iron trimetallic doped magnetic porous carbon based on all solid waste according to claim 1, characterized in that, The process after pyrolysis activation also includes washing and drying steps; the washing reagents are deionized water and acid solution; the concentration of the acid solution is 0.1~1 mol / L, and the acid solution is selected from hydrochloric acid, nitric acid or acetic acid.

9. A potassium-calcium-iron trimetallic doped magnetic porous carbon, characterized in that, The potassium-calcium-iron trimetallic doped magnetic porous carbon prepared according to any one of claims 1-8 has a hierarchical pore structure of micropores and mesopores.

10. The application of the potassium-calcium-iron trimetallic doped magnetic porous carbon of claim 9 in the adsorption and catalytic degradation of tetracycline hydrochloride.

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