A carbon-based adsorbent and its nitrogen-modified waste mask resource preparation method and application

Abstract

This invention discloses a carbon-based adsorbent and its nitrogen-modified waste mask resource utilization preparation method and application, belonging to the field of environmental functional materials technology. The method includes: firstly, crushing, removing impurities, and washing waste masks and agricultural and forestry waste; then performing ultrasonic-ball milling activation pretreatment; drying; followed by high-temperature pyrolysis under an inert atmosphere; then dispersing in water; adding a nitrogen-modifying reagent; and conducting a hydrothermal reaction. After cooling to room temperature, filtering and drying are performed to obtain nitrogen-modified waste mask-based carbon material. Finally, after microwave activation posttreatment, grinding and sieving, the carbon-based adsorbent is obtained. The method combines ultrasonic-ball milling activation pretreatment with co-pyrolysis and microwave activation posttreatment to activate waste masks and agricultural and forestry waste. The operation steps are simple, the equipment is basic, the cost is low, and there is no secondary pollution. The obtained carbon-based adsorbent has a porous structure, high specific surface area, contains micropores, and is virtually ash-free; it also exhibits excellent adsorption performance for the environmental hormone bisphenol A.

Description

Technical Field

[0001] This invention belongs to the field of environmental functional materials technology, specifically relating to a carbon-based adsorbent and its nitrogen-modified waste mask resource utilization preparation method and application. Background Technology

[0002] Discarded face masks typically consist of three layers: an outer hydrophobic nonwoven layer (semi-transparent), a middle meltblown layer (usually white), and an inner soft, absorbent nonwoven layer (green, blue, or white). The main materials of these masks are polypropylene and polyester fibers. Small amounts of other polymers such as polystyrene, polycarbonate, polyethylene, polyurethane, and polyacrylonitrile are also included. Discarded masks entering the environment not only release microfibers and microplastics but may also form aerosols that impact global climate and even pose a risk of viral infection, thus evolving into a new type of hazardous solid waste. These discarded masks can take up to 450 years to decompose naturally; therefore, the proper disposal of discarded masks is an urgent problem that needs to be solved, as it is of great benefit to human health and the environment.

[0003] Typically, discarded masks are sent to incinerators and landfills. However, because plastic incineration produces a large amount of toxic gases (such as dioxins), incineration is not recommended for disposing of discarded masks. Moreover, most masks are chemically stable, corrosion-resistant, and not easily degraded by microorganisms. Furthermore, discarded masks often remain in the soil after being landfilled, posing a significant threat to the environment. The resource utilization methods for discarded masks in China mainly include the following directions: (1) Energy utilization. Some places have tried to convert discarded masks into usable energy through incineration, but this method may produce gases and pollutants that are harmful to the human body. The plastics and other materials in discarded masks are also difficult to completely recycle and reuse because they may contain harmful substances such as viruses that are harmful to the human body, and need to be handled with caution. It can be seen that the energy utilization of discarded masks still needs further research and exploration in order to find more environmentally friendly and sustainable treatment methods. (2) Making recycled materials. Currently, some research institutions and enterprises in my country are exploring various methods to make recycled materials from discarded masks. One method is to process the cellulose and textile materials in discarded masks and convert them into recycled fibers. This recycled fiber can be used to manufacture various woven and nonwoven fabrics, such as masks, toilet paper, and wet wipes. This method is relatively mature and has already been initially applied in some companies and laboratories. In addition, some companies are attempting to recycle and reuse the plastic from discarded masks. This method requires detailed sorting and processing of discarded masks to extract the plastic materials. However, this method is relatively complex and requires significant technological and resource support. If successful, it will effectively reduce the environmental pollution caused by mask waste and promote resource recycling. Turning discarded masks into recycled materials is a relatively new field, requiring extensive research and exploration to find more effective and sustainable treatment methods, thereby reducing the environmental and resource impact of discarded mask waste. Many European countries utilize discarded masks as fuel or energy resources. In France, Belgium, Germany, and other European countries, companies recycle and reuse discarded disposable masks, processing them into pulp for paper and related products, or compressing them into high-density blocks for secondary processing to produce raw materials that can be used to manufacture other products. Some regions and cities in the United States encourage residents to recycle used face masks and take them to designated recycling points scattered throughout the city. Some companies have also begun collecting masks and converting them into reusable materials. For example, a company called "Mask-Escape" mixes discarded masks with some plastic products to create a new material that can be used in the construction industry. Meanwhile, in some parts of the United States, discarded masks are sent to waste incineration plants to be processed, converting them into usable energy through incineration; however, this method still inevitably causes environmental pollution.Compared to Europe, the United States still has much room for improvement in the resource utilization of discarded masks. Japan, a country that highly values ​​environmental protection and actively engages in resource recycling, has also taken relevant measures in the resource utilization of discarded masks. Some cities have already begun to implement recycling and reuse programs for discarded masks. For example, Tokyo, Japan, has established multiple discarded mask collection points, uniformly converting discarded masks into fiber raw materials for the production of new products. In short, although foreign countries have done relatively well in the resource utilization of discarded masks, more measures and policies are still needed to promote the resource utilization of discarded masks. Currently, most discarded masks, even if properly disposed of, cannot be recycled or chemically recycled. Common methods of disposing of discarded masks include landfill and incineration. Unfortunately, both methods can easily lead to the release of toxic secondary pollutants and pose a high risk of spreading viruses. This has forced scholars to explore more environmentally friendly and high-quality methods for the resource utilization of discarded masks. Among them, pyrolysis in an inert atmosphere provides a green, inexpensive, and reliable disposal process. Some scholars have found that this method can not only kill potential viruses but also convert discarded masks into functional carbon materials and high-quality bio-oils. Some scholars have also used a simple hydrothermal synthesis method to disinfect discarded masks and convert them into carbon dot materials, which are then applied to sodium sulfite and Fe. 3+ The spectral detection yielded good results. However, related research is still lacking, which puzzles scholars: Can discarded masks be recycled into carbon materials, and what are their effects on environmental applications? Moreover, is it feasible to prepare carbon-based adsorbents from discarded masks through co-pyrolysis? These preparation techniques and their environmental applications are still unclear or have not been reported.

[0004] In response to the technical problems of poor adsorption capacity, high cost, complex process and obvious pollution in the treatment of existing carbon materials for recycling waste masks, there is an urgent need to find a new carbon-based adsorbent that uses waste masks as raw materials, has a pollution-free preparation process, and is safe, environmentally friendly and green throughout the process, so as to realize the resource utilization of waste masks into carbon material adsorbents. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, the present invention aims to provide a carbon-based adsorbent and its nitrogen-modified waste mask resource utilization preparation method and application, so as to solve the technical problems of poor adsorption capacity, high cost, complex process and obvious pollution in the treatment process of existing resource utilization waste mask carbon materials.

[0006] To achieve the above objectives, the present invention employs the following technical solution:

[0007] This invention discloses a method for preparing carbon-based adsorbents from nitrogen-modified waste masks, comprising:

[0008] First, discarded masks and agricultural and forestry waste are crushed, cleaned, and purified. After ultrasonic-ball milling activation pretreatment and drying, they are dispersed in water after high-temperature pyrolysis under an inert atmosphere. A nitrogen-modifying reagent is added for hydrothermal reaction. After cooling to room temperature, the mixture is filtered and dried to obtain nitrogen-modified waste mask-based carbon material. Finally, after microwave activation, grinding, and sieving, a carbon-based adsorbent is obtained.

[0009] Preferably, the mass ratio of discarded masks to agricultural and forestry waste is 1:1, 2:1, or 1:2; the discarded masks are selected from at least one of ordinary masks, ordinary medical masks, medical surgical masks, and N95 masks; the agricultural and forestry waste is selected from at least one of wheat straw, corn straw, apple tree branches, jujube tree branches, cow dung, vines, fruit shells, edible fungus substrate, wood sawdust, and weeds.

[0010] Preferably, the conditions for ultrasonic-ball milling activation pretreatment include: ultrasonic frequency of 20-100kHz, ultrasonic power of 100-1000W, ultrasonic time of 1-10h; ball milling diameter of 5-30mm, ball milling time of 5-12h; and drying conditions include: drying temperature of 105-120℃, drying time of 2-12h.

[0011] Preferably, the inert atmosphere is any one or more of carbon dioxide, argon, helium, and nitrogen; the conditions for the high-temperature pyrolysis reaction include: 2-5℃·min -1 The heating rate is from room temperature to 225-475℃, and the temperature is maintained for 1-3 hours.

[0012] Preferably, the hydrothermal reaction conditions include: a hydrothermal reaction temperature of 175-225℃, a reaction time of 6-12h, and a reactor filling ratio of 50%-80%; the nitrogen-modifying reagent is urea, thiourea, melamine, or dicyandiamide; and the drying temperature is 105-120℃, with a drying time of 2-5h.

[0013] Preferably, the conditions for microwave activation post-treatment include: frequency of 1000MHz-30 GHz, power of 300-1000W, and time of 2-120min; the grinding and sieving conditions include: grinding time of 1-5h, and sieving particle size of 1-20mm.

[0014] The present invention also discloses a carbon-based adsorbent, which is prepared by the above preparation method.

[0015] Preferably, the specific surface area of ​​the carbon-based adsorbent is 20-500 m². 2 ·g -1 The pore volume is 0.02-0.96 cm³. 3 ·g -1 The average pore size is 0.8-48.9 nm; the ash content is ≤2.9 wt%.

[0016] The present invention also discloses the application of the above-mentioned carbon-based adsorbent in the treatment of industrial wastewater containing bisphenol A.

[0017] The present invention also discloses the application of the above-mentioned carbon-based adsorbent in soil improvement.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] This invention discloses a method for preparing carbon-based adsorbents from nitrogen-modified waste masks, comprising: first, crushing, removing impurities, and cleaning waste masks and agricultural and forestry waste; then, performing ultrasonic-ball milling activation pretreatment to clean the surface and internal fiber structure of the waste masks and agricultural and forestry waste, pre-activating the pores of the waste masks and agricultural and forestry waste, and removing impurities, thereby giving the prepared carbon-based adsorbent a porous structure and a high specific surface area; after drying, performing a high-temperature pyrolysis reaction under an inert atmosphere to fully carbonize the carbon-based adsorbent, ensuring that the specific surface area and porous structure of the carbon-based adsorbent are fully developed and reach a stable state, thereby significantly increasing the pore volume and specific surface area of ​​the prepared carbon-based adsorbent; then, dispersing the adsorbent in water, adding a nitrogen-modifying reagent, and performing a hydrothermal reaction; after cooling to room temperature, filtering, and drying, obtaining nitrogen-modified waste mask-based carbon material; finally, performing microwave activation posttreatment, grinding, and sieving to obtain the carbon-based adsorbent. This invention utilizes a pretreatment process of ultrasonic-ball milling activation, combined with a novel technology of co-pyrolysis of agricultural and forestry waste biomass. Simultaneously, microwave activation post-treatment significantly enhances the performance of the carbon-based adsorbent from waste masks. This results in a carbon-based adsorbent with a porous structure containing micropores, significantly increasing its specific surface area, and markedly reducing surface ash content and other impurities, thereby significantly increasing its adsorption performance in industrial wastewater containing bisphenol A (BPA). The preparation method of this carbon-based adsorbent is characterized by simple operation, easy equipment, low cost, and no secondary pollution release during adsorption. Using waste masks and agricultural and forestry waste materials as raw materials, it achieves a significant improvement in resource utilization. Roughly calculated for industrial batch production, preparing 1 kg of this carbon-based adsorbent requires only about 1 yuan of electricity. The adsorption process releases no secondary pollutants, and the subsequent separation and recovery effects are significant. Most importantly, it is suitable for large-scale factory production. Furthermore, evaluation shows that the preparation process of the carbon-based adsorbent from waste masks provided by this invention is safe, environmentally friendly, and green. This invention aligns with the green development concept of "achieving multiple benefits in one fell swoop, turning waste into treasure, and treating waste with waste," expanding new ideas for the comprehensive utilization of discarded masks and the preparation of environmentally functional materials. It also provides a theoretical basis for the removal of emerging pollutant BPA.

[0020] This invention discloses a carbon-based adsorbent prepared by the above-described method. This adsorbent possesses a porous structure, high specific surface area, microporous structure, and is virtually ash-free. It exhibits excellent adsorption performance for bisphenol A (BPA) in wastewater containing the endocrine disruptor BPA. It significantly increases the adsorption performance for BPA in industrial wastewater containing BPA, and even after five adsorption-desorption cycles, the adsorption efficiency for BPA remains above 50%. The saturated carbon-based adsorbent can also be used as a soil conditioner in farmland.

[0021] This invention discloses the application of the above-mentioned carbon-based adsorbent in the treatment of industrial wastewater containing bisphenol A. After five adsorption-desorption cycles, the adsorption effect on bisphenol A remains above 50%.

[0022] This invention discloses the application of the aforementioned carbon-based adsorbent in soil improvement. Its advantages primarily lie in the fact that the carbon-based adsorbent itself is an excellent carbon fixation material. Its preparation process reveals the presence of multiple carbon sources. When applied to the soil as a soil conditioner, it can increase the soil's organic carbon content, especially in arid and semi-arid regions of Northwest China. Furthermore, this carbon-based adsorbent contains nitrogen-modifying agents, such as urea, which is an excellent fertilizer source, providing nutrients to crops and promoting their growth and development. This carbon-based adsorbent can also regulate soil pH and micronutrient supply, providing a favorable rhizosphere environment for plants and increasing nutrient absorption efficiency and immunity. Based on the above analysis, this carbon-based adsorbent can also serve as a carrier and nutrient source for soil microorganisms, providing a suitable growth environment and nutrients, promoting the reproduction and activity of beneficial microorganisms in the soil. This helps improve soil biological activity, enhances soil nutrient transformation and organic matter decomposition capabilities, and promotes nutrient absorption and growth in plants. Furthermore, this carbon-based adsorbent exhibits excellent adsorption performance, effectively adsorbing harmful substances such as heavy metal ions, pesticide residues, and organic pollutants from the soil, reducing their harm to plants and the environment. This helps improve soil quality and environmental safety, protecting the health of plants and ecosystems. The adsorbent also possesses good adsorption properties, adsorbing and retaining soil moisture, reducing water loss and evaporation, and improving the soil's water retention capacity. This helps improve soil moisture conditions in arid or water-scarce areas, enhancing plant growth and survival conditions. In addition, the adsorbent itself contains a rich porous structure, increasing soil porosity and aeration, improving soil physical structure and soil aggregates. It also helps promote soil drainage and aeration, reducing waterlogging and root hypoxia, which is beneficial for plant root growth and respiration. Attached Figure Description

[0023] Figure 1 This is a scanning electron microscope image of the carbon-based adsorbent prepared in Example 1 of the present invention;

[0024] Figure 2 This is a scanning electron microscope image of the carbon-based adsorbent prepared in Example 2 of the present invention;

[0025] Figure 3 This is a scanning electron microscope image of the carbon-based adsorbent prepared in Example 3 of the present invention;

[0026] Figure 4 This is a scanning electron microscope image of the carbon-based adsorbent prepared in Example 4 of the present invention;

[0027] Figure 5 This is a scanning electron microscope image of the carbon-based adsorbent prepared in Example 5 of the present invention;

[0028] Figure 6 This is a scanning electron microscope image of the carbon-based adsorbent prepared in Example 6 of the present invention;

[0029] Figure 7 The infrared spectrum of the carbon-based adsorbent prepared in Example 1 of this invention;

[0030] Figure 8 The infrared spectrum of the carbon-based adsorbent prepared in Example 2 of this invention is shown. Detailed Implementation

[0031] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. 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 should fall within the scope of protection of the present invention.

[0032] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0033] The present invention is described in further detail below with reference to the accompanying drawings:

[0034] This invention provides a method for the resource recovery of carbon-based adsorbents from nitrogen-modified waste masks, comprising the following steps:

[0035] S1. Crush, remove impurities, and clean discarded masks and agricultural and forestry waste;

[0036] S2. Perform ultrasonic-ball milling activation pretreatment on the sample processed in step S1 to obtain the precursor material;

[0037] S3. After drying the precursor material obtained in step S2, a high-temperature pyrolysis reaction is carried out in the presence of an inert atmosphere to obtain waste mask-based carbon material.

[0038] S4. Disperse the waste mask-based carbon material obtained in step S3 in water, add nitrogen-modifying reagent, carry out hydrothermal reaction, cool to room temperature, filter, dry to obtain solid product, which is nitrogen-modified waste mask-based carbon material.

[0039] S5. The nitrogen-modified waste mask-based carbon material obtained in step S4 is subjected to microwave activation and then ground and sieved to obtain a carbon-based adsorbent.

[0040] In step S1, the mass ratio of discarded masks to agricultural and forestry waste is 1:1, 2:1, or 1:2.

[0041] Discarded masks are selected from at least one of the following: ordinary masks, ordinary medical masks, medical surgical masks, and N95 masks;

[0042] Agricultural and forestry waste is selected from at least one of the following: wheat straw, corn straw, apple tree branches, jujube tree branches, cow dung, vines, fruit shells, edible fungi substrate, wood sawdust, and weeds;

[0043] Preferably, the mass ratio of discarded masks to agricultural and forestry waste is 1:1; the discarded masks are medical surgical masks; and the agricultural and forestry waste is cow dung or fruit shells.

[0044] In step S2, the conditions for ultrasonic-ball milling activation pretreatment include: ultrasonic frequency of 20-100kHz, ultrasonic power of 100-1000W, and ultrasonic time of 1-10h.

[0045] The ball mill diameter is 5-30mm, and the ball milling time is 5-12h;

[0046] Preferably, the ultrasonic frequency is 40kHz, the ultrasonic power is 1000W, the ultrasonic time is 8h, the ball mill diameter is 5mm, and the ball milling time is 10h.

[0047] In step S3, the drying temperature is 105-120℃ and the drying time is 2-12h;

[0048] The conditions for high-temperature pyrolysis reactions include: 2-5℃·min -1The heating rate is increased from room temperature to 225-475℃ and maintained for 1-3 hours to carry out the high-temperature pyrolysis reaction;

[0049] The inert atmosphere is any one or more of carbon dioxide, argon, helium, and nitrogen;

[0050] Preferably, the drying temperature is 105℃ and the drying time is 10h; the heating rate of the high-temperature pyrolysis reaction is 2℃·min. -1 The temperature was raised to 375℃ and maintained for 2 hours; the inert atmosphere was carbon dioxide.

[0051] In step S4, the hydrothermal reaction conditions include: a hydrothermal reaction temperature of 175-225℃, a reaction time of 6-12h, and a reactor filling ratio of 50%-80%.

[0052] Nitrogen-modifying agents include: urea, thiourea, melamine, or dicyandiamide;

[0053] After cooling to room temperature and filtering, the product is dried at 105-120℃ for 2-5 hours.

[0054] Preferably, the hydrothermal reaction temperature is 200℃, the reaction time is 10h, the reactor filling ratio is 80%, the nitrogen-modifying agent is urea or thiourea, the drying temperature is 105℃, and the drying time is 5h.

[0055] In step S5, the conditions for microwave activation post-treatment include: frequency of 1000MHz~30GHz, power of 300-1000W, and time of 2-120min; the grinding and sieving conditions for microwave activation post-treatment include: grinding time of 1-5h and sieving particle size of 1-20mm.

[0056] Preferably, the microwave activation post-treatment frequency is 1200MHz, the power is 500W, and the time is 15min; the grinding time is 2h, and the sieve particle size is 10mm.

[0057] The carbon-based adsorbent prepared by this invention has a porous structure and a high specific surface area, ranging from 20 to 500 m². 2 ·g -1 The pore volume is 0.02-0.96 cm³. 3 ·g -1 The average pore size is 0.8-48.9 nm; the ash content is ≤2.9 wt%; this carbon-based adsorbent can treat industrial wastewater containing bisphenol A; this carbon-based adsorbent can also be added to farmland as a soil conditioner.

[0058] This invention employs a combination of ultrasonic-ball milling activation pretreatment and co-pyrolysis combined with microwave activation posttreatment to activate waste masks and carbon-based adsorbents, respectively. This significantly increases the porous structure and specific surface area of ​​the resulting carbon-based adsorbent from waste masks, while markedly reducing the ash content and other impurities on the adsorbent surface. This significantly enhances the adsorption performance of bisphenol A (BPA) in wastewater, and even after five adsorption-desorption cycles, the BPA adsorption efficiency remains above 50%. This invention uses waste masks and agricultural and forestry waste materials as raw materials, particularly waste masks and cow dung, achieving a significant improvement in resource utilization. The preparation method of the carbon-based adsorbent provided by this invention is simple to operate, low in cost (roughly calculated for industrial batch production, activating 1 kg of this carbon-based adsorbent requires only about 1 yuan of electricity), produces no secondary pollution, and exhibits significant subsequent separation and recovery effects. Most importantly, it is suitable for large-scale factory production, and evaluations have shown that the preparation process of the carbon-based adsorbent provided by this invention is safe, environmentally friendly, and green.

[0059] The carbon-based adsorbent prepared by the above-described preparation method disclosed in this invention has a specific surface area of ​​20-500 m². 2 ·g -1 The pore volume is 0.02-0.96 cm³. 3 ·g -1 The average pore size is 0.8-48.9 nm; the ash content is ≤2.9 wt%.

[0060] Preferably, the specific surface area of ​​the carbon-based adsorbent is 120-500 m². 2 ·g -1 The pore volume is 0.22-0.96 cm³. 3 ·g -1 The average pore size is 1.8-29.7 nm; the ash content is ≤0.15 wt%.

[0061] The carbon-based adsorbent disclosed in this invention can be applied to the treatment of industrial wastewater containing bisphenol A.

[0062] The carbon-based adsorbent disclosed in this invention can be used as a soil conditioner for soil improvement.

[0063] Bisphenol A (BPA, C) 15 H 16 O2 (oxygen dioxide) is a typical endocrine disruptor, commonly used in the production of polycarbonate and epoxy resins, and widely used in plastic products, food, and fine chemicals. As an emerging environmental pollutant, BPA has been detected in various water bodies and exhibits significant harmfulness. Upon entering the body, it can cause endocrine system disorders, potentially leading to reproductive dysfunction or inducing cancer. Because BPA has antioxidant properties, it is difficult to rapidly degrade; therefore, adsorption is the preferred method for efficiently removing BPA from water.

[0064] In this embodiment of the invention, cow dung was collected from Zhouzhi County, Xi'an City, Shaanxi Province; other raw materials and equipment used in the embodiments and comparative examples were commercially available products.

[0065] In this invention, the abbreviation MC stands for Mask carbon-based adsorbents, taken from the first letter MC.

[0066] Elemental content characterization: The elemental types and content ratios of the carbon-based adsorbent were determined using a Vario EL cubic elemental analyzer (Elementar Analysensysteme GmbH, Berlin, Germany) with argon as the carrier gas. The specific surface area, pore volume, and pore size of the carbon-based adsorbent were determined according to the national standard method GB / T 19587-2004, "Gas Adsorption BET Method," using nitrogen as the adsorbed gas. The testing instrument was a V-Sorb 2800P specific surface area and pore size analyzer from Beijing Jin'ai Spectrum Co., Ltd. The ash content of the carbon-based adsorbent was determined using a fully automated industrial analysis method, with approximate analysis performed using an XKGF-6000A automated industrial analyzer (Henan Xinke Analytical Instrument Co., Ltd., Hebi, China).

[0067] Example 1

[0068] A method for preparing carbon-based adsorbents from nitrogen-modified waste masks includes the following steps:

[0069] S1. Cut the medical surgical mask into 3cm pieces, rinse it several times with distilled water and air dry it. First, let the cow dung air dry naturally in the open air, then remove impurities and dry it in an oven at 105℃ for later use. Then weigh out the medical surgical mask and cow dung in a 1:1 mass ratio and mix them together.

[0070] S2. Place the sample processed in step S1 into clean water, control the ultrasonic frequency to 40kHz and the power to 1000W, and sonicate for 8 hours; dry at 105℃ for 10 hours; then ball mill the mixture in an air atmosphere, control the ball mill diameter to 5mm and set the ball milling time to 10 hours. After ultrasonic-ball milling activation pretreatment, the precursor material is obtained.

[0071] S3. Place the precursor material obtained in step S2 into a box furnace and heat it in a carbon dioxide atmosphere at 2°C·min. -1 The temperature was increased from room temperature to 375°C and held at that temperature for 2 hours to carry out a high-temperature pyrolysis reaction, resulting in waste mask-based carbon material.

[0072] S4. Disperse the waste mask-based carbon material obtained in step S3 in water and add nitrogen-modifying reagent urea. The reaction vessel is filled with 80% of the material. The reaction is carried out at 200°C for 10 hours to obtain nitrogen-modified waste mask-based carbon material. After cooling to room temperature, filter the material and dry it at 105°C for 5 hours to obtain nitrogen-modified waste mask-based carbon material.

[0073] S5. The nitrogen-modified waste mask-based carbon material obtained in step S4 is subjected to microwave activation post-treatment. The microwave activation post-treatment frequency is 1200MHz, the power is 500W, and the time is 15min. After grinding and sieving, the carbon-based adsorbent MC-1 is finally obtained. The grinding time of microwave activation post-treatment is 2h, and the sieved particle size is 10mm.

[0074] The specific surface area of ​​the carbon-based adsorbent MC-1 is 500.00 m². 2 ·g -1 The pore volume is 0.96 cm³. 3 ·g -1 The average pore size was 1.98 nm, and the ash content was 0.60 wt%. The elemental composition and physicochemical properties of the carbon-based adsorbent MC-1 were characterized, and the results are shown in Tables 1 and 2.

[0075] See Figure 1 This is a scanning electron microscope image of the carbon-based adsorbent prepared in Example 1 of the present invention; Figure 2 This is a scanning electron microscope image of the carbon-based adsorbent prepared in Example 2 of the present invention; Figure 3 This is a scanning electron microscope image of the carbon-based adsorbent prepared in Example 3 of the present invention; Figure 4 This is a scanning electron microscope image of the carbon-based adsorbent prepared in Example 4 of the present invention; Figure 5 This is a scanning electron microscope image of the carbon-based adsorbent prepared in Example 5 of the present invention; Figure 6 This is a scanning electron microscope (SEM) image of the carbon-based adsorbent prepared in Example 6 of the present invention; from Figure 1 It can be clearly observed that with nitrogen modification, the microsphere structure on the surface of the carbon-based adsorbent disappears, producing many flakes and particles, making the surface of the carbon-based adsorbent more fluffy and soft, like a sponge, with a large number of porous structures and dense, soft pores. Figure 2 The prepared carbon-based adsorbent has a large number of network structures, which are doped with micropores. There are also many irregular particles piled up on the surface of the carbon-based adsorbent. These may be esters produced by the pyrolysis reaction of polymers in the mask. Some of the sheet-like or cube-shaped particles may be crystals of polypropylene or the contents of the mask. Figure 3The results show that the unique fibers of cow dung, an agricultural and forestry waste, co-pyrolyze with the polymers in masks to produce microspheres or cubic crystals with spherical protrusions, which are widely distributed on the surface of the carbon-based adsorbent. This means that polymers introduced from discarded masks, such as polypropylene and polyester fibers, may undergo thermochemical reactions with natural biopolymers such as hemicellulose, cellulose, and lignin, affecting the overall structure of biochar and shaping microspherical particles through thermal polycondensation and pyrolysis. Figures 4-6 Similar situations exist in China, which indirectly indicates that nitrogen modification plays a role in activating the surface structure of biochar, further shaping the surface of biochar; at the same time, nitrogen-modifying agents may also react with waste mask-based carbon materials under hydrothermal conditions, leading to the fragmentation of microspheres.

[0076] See Figure 7 The infrared spectrum of the carbon-based adsorbent prepared in Example 1 of this invention; Figure 8 The image shows the infrared spectrum of the carbon-based adsorbent prepared in Example 2 of this invention. As can be seen from the image, both materials exhibit similar characteristic peaks, primarily including those at 3406 cm⁻¹. -1 The stretching vibration peak of the hydroxyl group (-OH) near the 2920 cm⁻¹ -1 Nearby CH stretching vibration peaks, such as methyl (-CH3), 1609 cm⁻¹ -1 The nearby amino (-NH2) resonance peak, 1437 cm⁻¹ -1 Nearby aromatic acid (-COOH) resonance peak, 1020 cm⁻¹ -1 Nearby C or C=C resonance peaks, and 400–800 cm⁻¹ -1 Nearby aromatic compounds such as pyridine or indole, and other heterocyclic functional groups. In particular, this carbon-based adsorbent exhibits high activity at 1560 cm⁻¹. -1 The characteristic peak may be an amino (-NH2) resonance peak. With co-pyrolysis and nitrogen modification, this resonance peak redshifts to 1606 cm⁻¹ in the NMB. -1 Nearby. Furthermore, based on the chemical composition characteristics of discarded masks and agricultural and forestry waste, 1560cm -1 The characteristic peaks are less likely to be nitrogen oxides, which are mainly obtained from the pyrolysis of the mask polymer (polyester fiber), and may also be affected by the participation of nitrogen-containing dyes in the pyrolysis reaction in discarded masks.

[0077] Example 2

[0078] A method for preparing carbon-based adsorbents from nitrogen-modified waste masks is disclosed. The carbon-based adsorbent is prepared according to the method in Example 1, with the following differences: In step S1, the agricultural and forestry waste is fruit shells, and the mass ratio of medical surgical masks to fruit shells is 1:2; In step S2, the ultrasonic frequency of the ultrasonic-ball milling activation pretreatment is 20 kHz, the ultrasonic power is 700 W, and the ultrasonic time is 10 h; the ball milling diameter is 10 mm, and the ball milling time is 12 h; the drying temperature is 105 °C, and the drying time is 8 h; In step S3, the inert atmosphere is nitrogen; the conditions for the high-temperature pyrolysis reaction are: 5 °C·min -1 The heating rate was increased from room temperature to 400℃ and held for 2.5 hours; in step S4, the hydrothermal reaction temperature was 205℃, the hydrothermal reaction time was 12 hours, and the reactor filling ratio was 70%; the nitrogen-modifying reagent was thiourea; after cooling to room temperature, the mixture was filtered and dried at 105℃ for 5 hours; in step S5, the microwave activation post-treatment frequency was 1000MHz, the power was 1000W, and the time was 10 minutes; the grinding time after microwave activation post-treatment was 3 hours, and the sieved particle size was 5 mm; carbon-based adsorbent MC-2 was obtained.

[0079] The specific surface area of ​​the carbon-based adsorbent MC-2 is 270.33 m². 2 ·g -1 The pore volume is 0.48 cm³. 3 ·g -1 The average pore size is 0.80 nm; the ash content is 1.50 wt%. The elemental composition and physicochemical properties of the carbon-based adsorbent MC-2 were characterized, and the results are shown in Tables 1 and 2.

[0080] Example 3

[0081] A method for preparing carbon-based adsorbents from nitrogen-modified waste masks is disclosed. The carbon-based adsorbent is prepared according to the method in Example 1, except that: in step S4, the hydrothermal reaction temperature is 205°C, the hydrothermal reaction time is 12h, and the reaction vessel filling ratio is 70%; the nitrogen-modifying reagent is thiourea; and carbon-based adsorbent MC-3 is obtained.

[0082] The specific surface area of ​​the carbon-based adsorbent MC-3 is 183.56 m². 2 ·g -1 The pore volume is 0.31 cm³. 3 ·g -1 The average pore size was 21.33 nm, and the ash content was 1.87 wt%. The elemental composition and physicochemical properties of the carbon-based adsorbent MC-3 were characterized, and the results are shown in Tables 1 and 2.

[0083] Example 4

[0084] A method for preparing carbon-based adsorbents from nitrogen-modified waste masks is disclosed. The carbon-based adsorbent is prepared according to the method in Example 1, except that: in step S5, the frequency of microwave activation post-treatment is 1000MHz, the power is 1000W, and the time is 10min; the grinding time of microwave activation post-treatment is 3h, and the sieve particle size is 5mm; carbon-based adsorbent MC-4 is obtained.

[0085] The specific surface area of ​​the carbon-based adsorbent MC-4 is 251.50 m². 2 ·g -1 The pore volume is 0.46 cm³. 3 ·g -1 The average pore size was 24.46 nm, and the ash content was 1.75 wt%. The elemental composition and physicochemical properties of the carbon-based adsorbent MC-4 were characterized, and the results are shown in Tables 1 and 2.

[0086] Example 5

[0087] A method for preparing carbon-based adsorbents from nitrogen-modified waste masks is disclosed. The method follows the procedure in Example 1, except that: in step S1, waste masks and cow dung are mixed at a mass ratio of 2:1; in step S2, the ultrasonic frequency for the ultrasonic-ball milling activation pretreatment is 20 kHz, the ultrasonic power is 700 W, and the ultrasonic time is 10 h; the drying temperature is 105 °C, and the drying time is 8 h; the ball milling diameter is 30 mm, and the ball milling time is 10 h; in step S3, the inert atmosphere is argon; and the high-temperature pyrolysis reaction conditions are: 3 °C·min⁻¹. -1 The heating rate was increased from room temperature to 475℃ and held for 3 hours; in step S4, the hydrothermal reaction temperature was 175℃, the hydrothermal reaction time was 12 hours, and the reactor filling ratio was 50%; the nitrogen-modifying reagent was melamine; after cooling to room temperature, the mixture was filtered and dried at 105℃ for 2 hours; in step S5, the microwave activation post-treatment frequency was 1000MHz, the power was 300W, and the time was 2 minutes; the grinding time after microwave activation post-treatment was 1 hour, and the sieved particle size was 1 mm; carbon-based adsorbent MC-5 was obtained.

[0088] The specific surface area of ​​the carbon-based adsorbent MC-5 is 306.78 m². 2 ·g -1 The pore volume is 0.51 cm³. 3 ·g -1 The average pore size was 10.67 nm, and the ash content was 1.43 wt%. The elemental composition and physicochemical properties of the carbon-based adsorbent MC-5 were characterized, and the results are shown in Tables 1 and 2.

[0089] Example 6

[0090] A method for preparing carbon-based adsorbents from nitrogen-modified waste masks is disclosed. The method follows the procedure in Example 1, except that: in step S1, waste masks and cow dung are mixed at a mass ratio of 1:2; in step S2, the ultrasonic frequency for the ultrasonic-ball milling activation pretreatment is 100 kHz, the ultrasonic power is 100 W, and the ultrasonic time is 1 h; the drying temperature is 105 °C, and the drying time is 8 h; the ball milling diameter is 30 mm, and the ball milling time is 10 h; in step S3, the inert atmosphere is helium; and the high-temperature pyrolysis reaction conditions are: 5 °C·min⁻¹. -1 The heating rate was increased from room temperature to 225℃ and held for 1 hour; in step S4, the hydrothermal reaction temperature was 225℃, the hydrothermal reaction time was 12 hours, and the reactor filling ratio was 80%; the nitrogen-modifying reagent was dicyandiamide; after cooling to room temperature, it was filtered and dried at 120℃ for 2 hours; in step S5, the microwave activation post-treatment frequency was 3000MHz, the power was 1000W, and the time was 100 minutes; the grinding time was 4 hours, and the sieved particle size was 20 mm; carbon-based adsorbent MC-6 was obtained.

[0091] The specific surface area of ​​the carbon-based adsorbent MC-6 is 20.00 m². 2 ·g -1 The pore volume is 0.02 cm³. 3 ·g -1 The average pore size was 48.9 nm, and the ash content was 2.90 wt%. The elemental composition and physicochemical properties of the carbon-based adsorbent MC-6 were characterized, and the results are shown in Tables 1 and 2.

[0092] Example 7

[0093] A method for preparing carbon-based adsorbents from nitrogen-modified waste masks is disclosed. The method follows the procedure in Example 1, except that: in step S1, ordinary masks and wheat straw are mixed at a mass ratio of 2:2; in step S2, the ultrasonic frequency for the ultrasonic-ball milling activation pretreatment is 60 kHz, the ultrasonic power is 200 W, and the ultrasonic time is 2 h; the drying temperature is 110 °C, and the drying time is 2 h; the ball milling diameter is 15 mm, and the ball milling time is 5 h; in step S3, the inert atmosphere is nitrogen; and the high-temperature pyrolysis reaction conditions are: 4 °C·min⁻¹. -1 The heating rate was increased from room temperature to 250℃ and held for 1.5 hours; in step S4, the hydrothermal reaction temperature was 220℃, the hydrothermal reaction time was 6 hours, and the reactor filling ratio was 60%; after cooling to room temperature, the mixture was filtered and dried at 110℃ for 3 hours; in step S5, the microwave activation post-treatment frequency was 5000MHz, the power was 800W, and the time was 50 minutes; the grinding time was 5 hours, and the sieved particle size was 15 mm; thus, carbon-based adsorbent MC-7 was obtained.

[0094] Example 8

[0095] A method for preparing carbon-based adsorbents from nitrogen-modified waste masks is disclosed. The method follows the procedure in Example 1, with the following differences: In step S1, ordinary medical masks and corn stalks are mixed at a mass ratio of 2:1; in step S2, the ultrasonic frequency for the ultrasonic-ball milling activation pretreatment is 80 kHz, the ultrasonic power is 500 W, and the ultrasonic time is 4 h; the drying temperature is 115 °C, and the drying time is 4 h; the ball milling diameter is 20 mm, and the ball milling time is 6 h; in step S3, the inert atmosphere is a mixture of nitrogen and argon; the high-temperature pyrolysis reaction conditions are: 4 °C·min -1 The heating rate was increased from room temperature to 250℃ and held for 1.5 hours; in step S4, the hydrothermal reaction temperature was 180℃ and the hydrothermal reaction time was 8 hours; after cooling to room temperature, the mixture was filtered and dried at 115℃ for 4 hours; in step S5, the microwave activation post-treatment frequency was 10 GHz, the power was 700 W, and the time was 80 minutes; carbon-based adsorbent MC-8 was obtained.

[0096] Example 9

[0097] A method for preparing carbon-based adsorbents from nitrogen-modified waste masks is disclosed. The method follows the procedure in Example 1, except that: in step S1, N95 masks and apple branches are mixed at a mass ratio of 1:1; in step S2, the ultrasonic frequency for the ultrasonic-ball milling activation pretreatment is 40 kHz, the ultrasonic power is 800 W, and the ultrasonic time is 6 h; the drying temperature is 120 °C, and the drying time is 6 h; the ball milling diameter is 25 mm, and the ball milling time is 7 h; in step S3, the high-temperature pyrolysis reaction conditions are: 4 °C·min -1 The heating rate was increased from room temperature to 300℃ and held for 1.5h; in step S5, the microwave activation post-treatment frequency was 30GHz, the power was 900W, and the time was 120min; carbon-based adsorbent MC-9 was obtained.

[0098] Example 10

[0099] A method for preparing carbon-based adsorbents from nitrogen-modified waste masks is disclosed. The carbon-based adsorbent is prepared according to the method in Example 1, with the following differences: In step S1, medical surgical masks and jujube tree branches are mixed at a mass ratio of 1:1; in step S2, the ultrasonic treatment time is 8 hours; the drying temperature is 105℃ and the drying time is 12 hours; the ball milling diameter is 5 mm and the ball milling time is 8 hours; in step S3, the high-temperature pyrolysis reaction conditions are: 4℃·min -1 The temperature was increased from room temperature to 325℃ and held for 1.5 hours to obtain carbon-based adsorbent MC-10.

[0100] Example 11

[0101] A method for preparing carbon-based adsorbents from nitrogen-modified waste masks is disclosed. The carbon-based adsorbent is prepared according to the method in Example 1, with the following differences: In step S1, a mixture of medical surgical masks and N95 masks (by mass ratio 1:1) and vines is mixed; in step S2, the drying time is 10 hours; the ball milling time is 9 hours; and in step S3, the high-temperature pyrolysis reaction conditions are: 4°C·min⁻¹. -1 The temperature was increased from room temperature to 350℃ and held for 2 hours to obtain carbon-based adsorbent MC-11.

[0102] Example 12

[0103] A method for preparing carbon-based adsorbents from nitrogen-modified waste masks is disclosed. The carbon-based adsorbent is prepared according to the method in Example 1, except that: in step S1, medical surgical masks and edible fungi substrate are mixed at a mass ratio of 1:1; in step S2, the ball milling time is 11 hours; and carbon-based adsorbent MC-12 is obtained.

[0104] Example 13

[0105] A method for preparing carbon-based adsorbents from nitrogen-modified waste masks is disclosed. The carbon-based adsorbent is prepared according to the method in Example 1, except that in step S1, medical surgical masks and wood sawdust are mixed in a mass ratio of 1:1 to obtain carbon-based adsorbent MC-13.

[0106] Example 14

[0107] A method for preparing carbon-based adsorbents from nitrogen-modified waste masks is disclosed. The carbon-based adsorbent is prepared according to the method in Example 1, except that in step S1, medical surgical masks and weeds are mixed in a mass ratio of 1:1 to obtain carbon-based adsorbent MC-14.

[0108] Example 15

[0109] A method for preparing carbon-based adsorbents from nitrogen-modified waste masks is disclosed. The carbon-based adsorbent is prepared according to the method in Example 1, except that in step S1, medical surgical masks and (a mixture of cow dung and fruit shells) are mixed in a mass ratio of 1:1 to obtain carbon-based adsorbent MC-15.

[0110] Comparative Example 1

[0111] The comparative carbon-based adsorbent was prepared according to the method of Example 1, except that steps S2 and S5 were not performed; comparative carbon-based adsorbent MB-1 was obtained, and the elemental content and physicochemical properties of comparative carbon-based adsorbent MB-1 were characterized, and the results are shown in Tables 1 and 2.

[0112] Comparative Example 2

[0113] The comparative carbon-based adsorbent was prepared according to the method of Example 1, except that step S5 was not performed; comparative carbon-based adsorbent MB-2 was obtained, and the elemental content and physicochemical properties of comparative carbon-based adsorbent MB-2 were characterized, and the results are shown in Tables 1 and 2.

[0114] Comparative Example 3

[0115] The comparative carbon-based adsorbent was prepared according to the method of Example 1, except that step S2 was not performed; comparative carbon-based adsorbent MB-3 was obtained, and the elemental content and physicochemical properties of comparative carbon-based adsorbent MB-3 were characterized, and the results are shown in Tables 1 and 2.

[0116] Table 1. Comparison of elemental content of carbon-based adsorbents prepared in Examples 1-6 and Comparative Examples 1-3 with comparative carbon-based adsorbents.

[0117]

[0118]

[0119] Note 1: The ash content here refers to the ash content in the carbon-based adsorbent through industrial analysis, not the ash content produced by biomass during biomass pyrolysis.

[0120] Table 2. Comparison of physicochemical properties of carbon-based adsorbents prepared in Examples 1-6 and Comparative Examples 1-3 with those of comparative carbon-based adsorbents.

[0121] Adsorbent <![CDATA[BET specific surface area (m 2 ·g -1 )]]> <![CDATA[Pore volume (cm 3 ·g -1 )]]> Average pore size (nm) MC-1 500.00 0.96 1.98 MC-2 270.33 0.48 0.80 MC-3 183.56 0.31 21.33 MC-4 251.50 0.46 24.46 MC-5 306.78 0.51 10.67 MC-6 20.00 0.02 48.9 MB-1 1.13 0.01 43.26 MB-2 13.15 0.01 26.69 MB-3 4.49 0.01 38.24

[0122] Table 1 compares the elemental content of the carbon-based adsorbents prepared in Examples 1-6 and Comparative Examples 1-3 with the comparative carbon-based adsorbents; Table 2 compares the physicochemical properties of the carbon-based adsorbents prepared in Examples 1-6 and Comparative Examples 1-3 with the comparative carbon-based adsorbents. As can be seen from Tables 1 and 2, compared to the comparative carbon-based adsorbents MB-1 to MB-3 prepared in Comparative Examples 1-3, the ash content of the carbon-based adsorbents MC-1 to MC-6 prepared in Examples 1-6 of this invention is significantly reduced, while the oxygen and nitrogen content is significantly higher. Furthermore, the carbon-based adsorbents prepared in Examples 1-6 have significantly increased specific surface area and pore volume, while the average pore size is reduced. This indicates that the waste mask carbon-based adsorbents prepared in Examples 1-6 of this invention have a porous structure containing micropores (average pore size less than 2 nm) and possess superior adsorption capacity.

[0123] Application test cases

[0124] 1. Application test of bisphenol A adsorption

[0125] a. Indoor Simulation Experiment: Bisphenol A (BPA) solutions were all mixed with 1 mL of anhydrous ethanol as a solvent to ensure complete dissolution at room temperature (25℃). The pH of the solution was adjusted to approximately neutral using dilute NaOH and dilute HCl. Sufficient centrifuge tubes were filled with 50 mL of a specific concentration of BPA solution and 0.05 g of the preparation material, and placed in an air bath constant-temperature shaker. The mixture was shaken at 240 rpm for 24 h at room temperature. The mixture was then centrifuged at high speed for solid-liquid separation. The solid filter residue was dried at 80℃ for 24 h and recovered. The filtrate was stored in a reagent bottle, protected from light, sealed, and refrigerated for later use. After dilution, it was used to analyze the concentration of the adsorbate. Each treatment was performed in triplicate, with a control and a blank treatment included. The mean values ​​were calculated using statistical methods for subsequent analysis. Furthermore, the accuracy of the BPA concentration in the adsorption experiment was calibrated using a standard curve and samples of known concentrations. The BPA concentration was determined using a Shimadzu Nexera UHPLC LC-30A ultra-high performance liquid chromatograph (UHPLC), and the adsorption capacity was calculated based on the difference in BPA concentration before and after the adsorption experiment. The adsorption capacity Q can be calculated using the following formula. e Removal rate (RE):

[0126]

[0127]

[0128] In the formula, Q e The adsorption amount at adsorption equilibrium (mg·g) -1 C0 is the initial solution concentration (mg·L⁻¹). -1 ); C e The concentration of the solution at adsorption equilibrium (mg·L) -1 V is the solution volume (L); m is the amount of carbon-based adsorbent used (g). The adsorption test results are shown in Table 3.

[0129] Table 3. Application test results of carbon-based adsorbents and comparative carbon-based adsorbents prepared in Examples 1-6 and Comparative Examples 1-3 for adsorbing bisphenol A.

[0130]

[0131] Table 3 (continued)

[0132]

[0133]

[0134] Table 3 shows the application test results of the carbon-based adsorbents and comparative carbon-based adsorbents prepared in Examples 1-6 and Comparative Examples 1-3 for the adsorption of bisphenol A. As can be seen from Table 3, overall, the average adsorption capacity of the carbon-based adsorbent MC prepared in the examples for bisphenol A is 2-6 times that of the comparative carbon-based adsorbent MB prepared in the comparative examples; compared with MB, the removal rate of bisphenol A by MC is also significantly increased by about 3-8 times, especially at higher concentrations of bisphenol A. Among them, MC-1 has the highest average adsorption capacity and removal rate for bisphenol A, followed by MC-5, MC-2, MC-4, MC-3, and MC-6. It is evident that carbon-based adsorbents subjected to ultrasonic-ball milling activation pretreatment, combined co-pyrolysis technology, and microwave activation posttreatment can significantly enhance the adsorption performance of materials for bisphenol A.

[0135] b. Application test in industrial wastewater: Collect sufficient amount of bisphenol A-containing wastewater from a factory, measure the bisphenol A content in the industrial wastewater, and then dilute it to 5-200 mg / L. -1 Then, accurately weigh 0.1000 g of the carbon-based adsorbent samples prepared in the examples and comparative examples and place them in a 250 mL Erlenmeyer flask. Add 50 mL of industrial wastewater containing BPA of different concentrations. Place the Erlenmeyer flasks, covered with plastic film, in a constant-temperature air bath shaker and shake at 150 rpm for 3 hours, without setting a reaction temperature. Afterward, filter the mixture using a 0.45 μm microporous membrane (50 mm diameter, filtration efficiency >99%) (or use high-speed centrifugation) to separate the solid and liquid phases and obtain the filtrate. Analyze the filtrate using a Shimadzu Nexera UHPLC LC-30A ultra-high performance liquid chromatograph to determine the BPA concentration. All treatments were repeated three times, and the average value was calculated. The adsorption test results are shown in Table 4.

[0136] Table 4 shows the adsorption test results of the carbon-based adsorbents prepared in Examples 1-6 and Comparative Examples 1-3 for bisphenol A-containing wastewater.

[0137]

[0138]

[0139] Table 4 (continued)

[0140]

[0141] Table 4 shows the adsorption test results of the carbon-based adsorbents and comparative carbon-based adsorbents prepared in Examples 1-6 and Comparative Examples 1-3 for bisphenol A-containing wastewater. As can be seen from Table 4, overall, the average adsorption capacity of the carbon-based adsorbent MC prepared in the examples for bisphenol A is 2-5 times that of the comparative carbon-based adsorbent MB prepared in the comparative examples. Compared with MB, the removal rate of bisphenol A by MC is also significantly increased by about 2-8 times, especially when the concentration of bisphenol A is high. Among them, MC-1 has the largest average adsorption capacity and removal rate of bisphenol A, followed by MC-2, MC-4, MC-5, MC-3, and MC-6. It is evident that the combined ultrasonic-ball milling activation pretreatment and co-pyrolysis technology, along with microwave activation posttreatment, significantly enhances the adsorption performance of the material for bisphenol A. Furthermore, a comparison between Table 4 and Table 3 shows that, due to the presence of various interfering ions in industrial wastewater, the actual situation is more complex than the indoor simulation experiment. However, for the same material, MC exhibits a more significant adsorption effect on industrial wastewater than the indoor simulation experiment, with a significantly higher average removal rate. This implies that MC is more suitable for industrial wastewater treatment; conversely, MB does not show this phenomenon.

[0142] 2. Desorption-Reusability Test

[0143] a) Distilled Water Test: Weigh 0.1000g of carbon-based adsorbent sample (test b) to the industrial wastewater used in the bisphenol A adsorption test, ensuring saturation adsorption. Immerse the sample in distilled water; the ratio of solid carbon-based adsorbent to liquid distilled water is 1:50. Shake the solution at 150 rpm for 24 hours at 25°C to allow bisphenol A desorption from the carbon-based adsorbent. Filter off the solid carbon-based adsorbent to obtain the filtrate. Determine the BPA concentration using a Shimadzu Nexera UHPLC LC-30A ultra-high performance liquid chromatograph. Calculate the desorption efficiency (DE; %) of the carbon-based adsorbent for bisphenol A as follows:

[0144]

[0145] Where C d and V d These are the concentrations (mg·L) of bisphenol A in the desorption solution. -1 The adsorption volume (L) was measured. The desorbed MC was washed with deionized water until neutral and then dried for recirculation. The reusability of the carbon-based adsorbent was evaluated by performing five consecutive adsorption-desorption cycles and checking the average value. The desorbed carbon-based adsorbent underwent adsorption performance testing according to application test b in the bisphenol A adsorption test for industrial wastewater to evaluate the reusability of the desorbed carbon-based adsorbent. The initial bisphenol A concentration was 50 mg·L⁻¹. -1 .

[0146] b. HCl test: Weigh 0.1000g of carbon-based adsorbent sample that has reached saturation adsorption in the industrial wastewater used for the bisphenol A adsorption test (b), and then immerse it in 0.1mol·L⁻¹ HCl solution. -1 The carbon-based adsorbent solid and distilled water were mixed in HCl at a ratio of 1:50. The solution was shaken at 150 rpm for 24 hours at 25°C to desorb bisphenol A (BPA) from the carbon-based adsorbent. The solid carbon-based adsorbent was filtered off to obtain the filtrate, which was then analyzed using a Shimadzu Nexera UHPLC LC-30A ultra-high performance liquid chromatograph to determine the BPA concentration. The desorbed carbon-based adsorbent was washed with deionized water until neutral and then dried for recycling. The reusability of the carbon-based adsorbent was evaluated by performing five consecutive adsorption-desorption cycles and checking the average value. The desorbed carbon-based adsorbent was subjected to adsorption performance testing according to application test b in the application test of BPA adsorption in industrial wastewater to evaluate the reusability of the desorbed carbon-based adsorbent. The initial BPA concentration was 50 mg·L⁻¹. -1 .

[0147] c. KCl test: Weigh 0.1000g of carbon-based adsorbent sample from industrial wastewater in the bisphenol A adsorption test (b) to achieve saturated adsorption, and then immerse it in 1mol·L⁻¹ KCl solution. -1 The carbon-based adsorbent solid and distilled water liquid were mixed in KCl at a ratio of 1:50. The solution was shaken at 150 rpm for 24 h at 25 °C to desorb bisphenol A (BPA) from the carbon-based adsorbent. The solid carbon-based adsorbent was filtered off to obtain the filtrate, which was then analyzed using a Shimadzu Nexera UHPLC LC-30A ultra-high performance liquid chromatograph to determine the BPA concentration. The desorbed carbon-based adsorbent was washed with deionized water until neutral and then dried for recycling. The reusability of the carbon-based adsorbent was evaluated by performing five consecutive adsorption-desorption cycles and checking the average value. The desorbed carbon-based adsorbent was subjected to adsorption performance testing according to application test b in the application test of BPA adsorption in industrial wastewater to evaluate the reusability of the desorbed carbon-based adsorbent. The initial BPA concentration was 50 mg·L⁻¹. -1 The results of the desorption-reuse test are shown in Table 5.

[0148] Table 5 shows the desorption-reuse test results of the carbon-based adsorbents prepared in Examples 1-6 and Comparative Examples 1-3, and the comparative carbon-based adsorbents.

[0149]

[0150]

[0151] Table 5 shows the desorption-reuse test results of the carbon-based adsorbents prepared in Examples 1-6 and Comparative Examples 1-3, and the comparative carbon-based adsorbents. As can be seen from Table 5, overall, 1 mol·L⁻¹… -1 The desorption effect of HCl was the most significant, followed by 0.1 mol·L⁻¹. -1 KCl and distilled water showed the worst desorption effect. On average, MB had a significantly better desorption effect than MC, meaning that MC is not easily desorbed after adsorbing bisphenol A, highlighting the adsorption stability of the carbon-based adsorbent material from waste masks. Furthermore, after five adsorption-desorption cycles for reuse, it was found that MC-1, MC-2, MC-3, MC-4, MC-5, and MC-6 maintained a bisphenol A removal rate of over 60%, significantly higher than the average of MB-1, MB-2, and MB-3. This demonstrates that the carbon-based material prepared in this invention has superior performance in recycling.

[0152] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A method for the resource-based preparation of carbon-based adsorbents from nitrogen-modified waste masks, characterized in that, include: First, discarded masks and agricultural and forestry waste are crushed, cleaned, and purified. After ultrasonic-ball milling activation pretreatment and drying, they are dispersed in water after high-temperature pyrolysis under an inert atmosphere. A nitrogen-modifying reagent is added for hydrothermal reaction. After cooling to room temperature, the mixture is filtered and dried to obtain nitrogen-modified waste mask-based carbon material. Finally, after microwave activation, grinding, and sieving, a carbon-based adsorbent is obtained.

2. The method for preparing carbon-based adsorbents from nitrogen-modified waste masks according to claim 1, characterized in that, The discarded masks are made of agricultural and forestry waste in a mass ratio of 1:1, 2:1, or 1:

2. The discarded masks are selected from at least one of ordinary masks, ordinary medical masks, medical surgical masks, and N95 masks. The agricultural and forestry waste is selected from at least one of wheat straw, corn straw, apple tree branches, jujube tree branches, cow dung, vines, fruit shells, edible fungus substrate, wood sawdust, and weeds.

3. The method for preparing carbon-based adsorbents from nitrogen-modified waste masks according to claim 1, characterized in that, The conditions for the ultrasonic-ball milling activation pretreatment include: ultrasonic frequency of 20-100kHz, ultrasonic power of 100-1000W, ultrasonic time of 1-10h; ball milling diameter of 5-30mm, ball milling time of 5-12h; and the drying conditions include: drying temperature of 105-120℃, drying time of 2-12h.

4. The method for preparing carbon-based adsorbents from nitrogen-modified waste masks according to claim 1, characterized in that, The inert atmosphere is any one or more of carbon dioxide, argon, helium, and nitrogen; the conditions for the high-temperature pyrolysis reaction include: heating from room temperature to 225-475°C at a heating rate of 2-5°C·min⁻¹, and holding the temperature for 1-3 hours.

5. The method for preparing carbon-based adsorbents from nitrogen-modified waste masks according to claim 1, characterized in that, The hydrothermal reaction conditions include: a hydrothermal reaction temperature of 175-225℃, a reaction time of 6-12h, and a reactor filling ratio of 50%-80%; the nitrogen-modifying reagent is urea, thiourea, melamine, or dicyandiamide; the drying temperature is 105-120℃, and the drying time is 2-5h.

6. The method for preparing carbon-based adsorbents from nitrogen-modified waste masks according to claim 1, characterized in that, The conditions for microwave activation post-treatment include: frequency of 1000MHz-30 GHz, power of 300-1000W, and time of 2-120min; the conditions for grinding and sieving include: grinding time of 1-5h and sieving particle size of 1-20mm.

7. A carbon-based adsorbent, characterized in that, It is prepared by the preparation method described in any one of claims 1-6.

8. The carbon-based adsorbent according to claim 7, characterized in that, The specific surface area of ​​this carbon-based adsorbent is 20-500 m². 2 ·g -1 The pore volume is 0.02-0.96 cm³. 3 ·g -1 The average pore size is 0.8-48.9 nm; the ash content is ≤2.9 wt%.

9. The application of the carbon-based adsorbent according to claim 7 in the treatment of industrial wastewater containing bisphenol A.

10. The application of the carbon-based adsorbent of claim 7 in soil improvement.

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