A graphite-based base charged adsorbent for solid waste, its preparation method, and its application in air carbon capture.

Abstract

This invention discloses a solid waste graphite-based base charged adsorbent, its preparation method, and its application in air carbon capture, belonging to the field of adsorbent technology. The preparation method provided by this invention involves steps such as acid washing of solid waste graphite, high-temperature expansion, gradient pore formation, and electrochemical activation to obtain a solid waste graphite-based base charged adsorbent. This adsorbent can operate in low CO2 environments, achieving an adsorption efficiency of 0.6 mmol / g, and retains 95% of its adsorption capacity after 100 cycles, exhibiting high stability. The raw material for this adsorbent is solid waste graphite, resulting in low cost and reduced environmental pollution. Therefore, the solid waste graphite-based base charged adsorbent provided by this invention has excellent industrial prospects.

Description

Technical Field

[0001] This invention belongs to the field of adsorbent technology, specifically relating to a graphite-based base charged adsorbent for solid waste, its preparation method, and its application in air carbon capture. Background Technology

[0002] Direct carbon capture (DAC) is a key negative emission technology for addressing climate change, but existing adsorbents face challenges such as high cost, high regeneration energy consumption, and low adsorption efficiency for low-concentration CO2. Current mainstream technologies include: liquid adsorption technologies (such as alkaline solutions and amine solutions): requiring high-temperature regeneration (>120℃), high energy consumption (2.5-3.5 GJ / tCO2), and equipment prone to corrosion. Solid amine adsorbents: relying on the functionalization of organic amines (such as polyethyleneimine), but amine groups easily clog pores, leading to increased mass transfer resistance and significant amine volatilization losses.

[0003] Metal-organic frameworks (MOFs): Although they have high adsorption capacity, they are expensive to synthesize (>1000 USD / kg) and have poor stability.

[0004] The rise of charged adsorption technology has provided a new path to overcome the aforementioned bottlenecks. This technology uses electrochemical modulation of the surface charge state of the adsorbent to achieve capture through the acid-base neutralization reaction of CO2 with hydroxyl ions. A novel graphite-based charged adsorbent for directly capturing carbon dioxide from the air is introduced. This material uses electrochemical charging to embed hydroxide ions into the pores of low-cost activated carbon, forming chemisorption sites, which can efficiently capture CO2 and generate carbonates at room temperature. Compared with traditional methods, its regeneration temperature is significantly reduced (90-100℃), and it supports Joule heating, requiring only renewable energy power. Experiments show that the material has a CO2 adsorption capacity of 0.26 mmol / g under low pressure, maintains stable performance after 150 cycles, and exhibits antioxidant properties. In real-world environmental testing, the CO2 concentration was reduced from 500 ppm to 25 ppm within 25 minutes. This technology combines low cost, controllability, and conductivity, providing a new direction for low-carbon DAC (deionization-induced degradation) processes. However, this graphite-based adsorbent has the following problems: traditional graphite materials require high-purity raw materials, resulting in high raw material acquisition costs. Meanwhile, the purification of natural graphite is characterized by high pollution and high energy consumption. Graphite resources, such as those found in spent lithium-ion batteries, have significant application potential in fields like new energy and the electronics industry. Therefore, the recycling of negative electrode graphite materials into porous charged adsorbents is urgently needed. Furthermore, existing traditional adsorbents lack electrochemical activation and gradient pore design, resulting in low adsorption capacity and high desorption energy consumption. Summary of the Invention

[0005] In view of the above-mentioned prior art, the present invention provides a solid waste graphite-based base charged adsorbent, its preparation method and its application in air carbon capture, which solves the problems of high cost and low efficiency of the prior art.

[0006] To achieve the above objectives, the technical solution adopted by this invention is: to provide a method for preparing a solid waste graphite-based base charged adsorbent, comprising the following steps:

[0007] S1: Pickle the solid waste graphite, then place the pickled solid waste graphite in an inert gas atmosphere and keep it at 750-850℃ for 2-3 hours. After the heat preservation is completed, grind it into powder with a particle size ≤50μm to obtain pretreated solid waste graphite.

[0008] S2: Mix pretreated solid waste graphite and CaCO3, then add H2O2 and stir evenly to obtain a composite slurry;

[0009] S3: The composite slurry is molded into a film of 0.2-0.3 mm, and the film is vacuum dried at 100°C for 24 h and then cut into graphite electrode sheets;

[0010] S4: In KOH electrolyte, with graphite electrode sheet as working electrode, Pt as counter electrode and SCE as reference electrode, the solid waste graphite-based base charged adsorbent is obtained by continuous operation at 2V for 2h.

[0011] The beneficial effects of this invention are as follows: The method provided by this invention utilizes solid waste graphite as raw material, significantly reducing raw material costs. Through pretreatment of the solid waste graphite (acid washing, expansion, and ball milling), acid washing removes surface impurities, expansion forms a porous or loose structure, and ball milling reduces graphite particle size and optimizes morphology. Then, the graphite is mixed with CaCO3, followed by gradient oxidation etching with H2O2 to obtain a gradient pore distribution of macropores, mesopores, and micropores, increasing the specific surface area. Finally, after electrochemical activation and the introduction of OH... - This yields a graphite-based base charged adsorbent for solid waste.

[0012] Based on the above technical solution, the present invention can be further improved as follows.

[0013] Furthermore, the pickling process involves soaking solid waste graphite in 20% hydrochloric acid for 10–20 minutes.

[0014] Further grinding involves ball milling solid waste graphite at a speed of 300–500 r / min.

[0015] The beneficial effects of adopting further technical solutions are: to obtain pretreated graphite with fewer impurities, smaller particle size, and better morphology and structure.

[0016] Furthermore, the mass ratio of graphite to CaCO3 in the pretreated solid waste is 1:2 to 5.

[0017] Furthermore, the material ratio of the pretreated solid waste graphite and CaCO3 mixture to H2O2 is 1g:1-3mL.

[0018] The beneficial effect of adopting the further technical solution is that it enables the obtained solid waste graphite-based base charged adsorbent to have a reasonable gradient pore distribution, allowing for the embedding of more OH groups. - .

[0019] Furthermore, the electrolyte is a KOH solution or a NaHCO3 solution.

[0020] Furthermore, the charging process involves constant voltage charging at 2V for 2 hours or pulse charging at 0.5V with 10-minute intervals for 2 hours.

[0021] The beneficial effect of adopting a further technical solution is that OH groups can be embedded on the surface of the gradient channels through electrochemical means. - This significantly improves the performance of the final solid waste graphite-based base charged adsorbent.

[0022] The present invention also provides a method for preparing a solid waste graphite-based base charged adsorbent, which yields a solid waste graphite-based base charged adsorbent.

[0023] This invention also provides the application of solid waste graphite-based base charged adsorbents in air carbon capture.

[0024] The beneficial effects of this invention are as follows: The solid waste graphite-based base charged adsorbent provided by this invention reuses solid waste graphite. Moreover, the synergistic design of gradient channels and electrochemical activation enables the adsorbent to achieve excellent performance. In a low CO2 concentration environment, the dynamic adsorption capacity reaches 3.2 mmol / g, and the adsorption capacity only decreases slightly in a high humidity environment. The electrochemical desorption energy consumption is 0.6 GJ / t CO2, the CO2 desorption rate is >95%, and the capacity retention rate is about 95% after 100 cycles. Its excellent performance allows it to be used on a large scale in DACs. Therefore, this solid waste graphite-based base charged adsorbent has excellent industrial prospects. Attached Figure Description

[0025] Figure 1 Here is a SEM image of solid waste graphite from Example 1;

[0026] Figure 2 Here is a macroporous SEM image of the solid waste graphite-based base charged adsorbent prepared in Example 1;

[0027] Figure 3 Mesoporous SEM image of the solid waste graphite-based base charged adsorbent prepared in Example 1;

[0028] Figure 4 The image shows the micropores of the solid waste graphite-based base charged adsorbent prepared in Example 1.

[0029] Figure 5 This is a flow chart of the adsorption-regeneration cycle;

[0030] Figure 6 This is a statistical chart of adsorption performance;

[0031] Figure 7 This is a graph showing the cyclic performance. Detailed Implementation

[0032] The specific embodiments of the present invention will be described in detail below with reference to examples.

[0033] Example 1

[0034] A graphite-based base charged adsorbent for solid waste is prepared by the following steps:

[0035] S1: Immerse solid waste graphite in 6M HCl and stir at 60℃ for 2h. Then wash the acid-washed solid waste graphite with deionized water until neutral. Place it under nitrogen atmosphere and keep it at 800℃ for 2.5h. After the heat preservation is completed, grind it into powder with a particle size ≤50μm to obtain pretreated solid waste graphite.

[0036] S2: Mix pretreated solid waste graphite and CaCO3 at a mass ratio of 1:3, then add H2O2 and stir evenly (the material ratio of the mixture of pretreated solid waste graphite and CaCO3 to H2O2 is 1g:2mL) to obtain a composite slurry;

[0037] S3: The composite slurry is molded into a 0.25mm film, and the film is vacuum dried at 100℃ for 24h and then cut into graphite electrode sheets;

[0038] S4: In 1M KOH electrolyte, with graphite electrode sheet as working electrode, Pt as counter electrode, and SCE as reference electrode, constant voltage charging at 2V for 2h yields solid waste graphite-based base charged adsorbent.

[0039] Example 2

[0040] A method for preparing a graphite-based base charged adsorbent for solid waste includes the following steps:

[0041] S1: Immerse solid waste graphite in 6M HCl, stir at 60℃ for 2h, then wash the acid-washed solid waste graphite with deionized water until neutral, place it under nitrogen atmosphere, keep it at 750℃ for 3h, after the heat preservation is completed, grind it into powder with a particle size ≤50μm to obtain pretreated solid waste graphite.

[0042] S2: Mix pretreated solid waste graphite and CaCO3 at a mass ratio of 1:2, then add H2O2 and stir evenly (the material ratio of the mixture of pretreated solid waste graphite and CaCO3 to H2O2 is 1g:1mL) to obtain a composite slurry.

[0043] S3: The composite slurry is molded into a 0.2 mm film, and the film is vacuum dried at 100℃ for 24 h and then cut into graphite electrode sheets;

[0044] S4: In 1M NaHCO3 electrolyte, with graphite electrode sheet as working electrode, Pt as counter electrode and SCE as reference electrode, the solid waste graphite-based base charged adsorbent is obtained by pulse charging at 0.5V and 10min intervals for 2h.

[0045] Example 3

[0046] A graphite-based base charged adsorbent for solid waste is prepared by the following steps:

[0047] S1: Immerse solid waste graphite in 6M HCl, stir at 60℃ for 2h, then wash the acid-washed solid waste graphite with deionized water until neutral, place it under nitrogen atmosphere, keep it at 850℃ for 2h, after the heat preservation is completed, grind it into powder with a particle size ≤50μm to obtain pretreated solid waste graphite.

[0048] S2: Mix pretreated solid waste graphite and CaCO3 at a mass ratio of 1:5, then add H2O2 and stir evenly (the material ratio of the mixture of pretreated solid waste graphite and CaCO3 to H2O2 is 1g:3mL) to obtain a composite slurry.

[0049] S3: The composite slurry is molded into a 0.3 mm film, and the film is vacuum dried at 100℃ for 24 h and then cut into graphite electrode sheets;

[0050] S4: In 1M KOH electrolyte, with graphite electrode sheet as working electrode, Pt as counter electrode, and SCE as reference electrode, constant voltage charging at 2V for 2h yields solid waste graphite-based base charged adsorbent.

[0051] Comparative Example 1

[0052] A graphite-based base charged adsorbent, the preparation method of which includes the following steps:

[0053] S1: Immerse commercial high-purity graphite powder in 6M HCl solution and stir at 60℃ for 2h. Then wash the acid-washed graphite powder with deionized water until neutral, and then vacuum dry at 80℃ for 12h to obtain pretreated graphite powder.

[0054] S2: Pretreated graphite powder and KOH were mixed at a mass ratio of 1:3, and the mixture was placed under a nitrogen atmosphere and activated at 800℃ for 1 h. After activation, it was washed once with 0.1M HCl solution and then vacuum dried at 80℃ to constant weight to obtain single-pore graphite.

[0055] S3: In 1M KOH electrolyte, using single-channel graphite as the working electrode, Pt as the counter electrode, and a saturated calomel electrode as the reference electrode, a constant voltage charging at 2V for 2 hours yields a graphite-based base charged adsorbent.

[0056] Comparative Example 2

[0057] This comparative example is solid waste graphite that has been acid-washed and expanded at high temperature;

[0058] Solid waste graphite was immersed in 6M HCl and stirred at 60°C for 2 hours. Then, the acid-washed solid waste graphite was washed with deionized water until neutral and placed in a nitrogen atmosphere at 800°C for 2.5 hours to obtain pretreated solid waste graphite.

[0059] The solid waste graphite-based charged adsorbents prepared in Examples 1 to 3 of this invention have similar performance effects, and the solid waste graphite-based charged adsorbent prepared in Example 1 was used in subsequent experiments.

[0060] Experimental Example 1

[0061] Characterization experiments: The raw material (solid waste graphite) used in Example 1 and the solid waste graphite-based charged adsorbent prepared in Example 1 were analyzed using scanning electron microscopy. The SEM images of the solid waste graphite are shown below. Figure 1 As shown, the SEM image of the solid waste graphite-based base charged adsorbent prepared in Example 1 is as follows. Figures 2-4 As shown, different pore sizes correspond to macropores, mesopores, and micropores, respectively, indicating that the solid waste graphite-based base charged adsorbent prepared in Example 1 successfully formed a gradient pore distribution on the solid waste graphite.

[0062] Experiment Example 2

[0063] Adsorption-regeneration cycle experiment: according to Figure 5 The process was used to conduct adsorption-regeneration cycle experiments on Examples 1 and 2. The adsorption environment was 25°C and 400 ppm CO2. The regeneration conditions for Example 1 were applying a reverse voltage (-2V) and CO3. 2 - Decomposes into CO2 and O2-, OH- is regenerated in situ, and the regeneration energy consumption is 0.6 GJ / tCO2; the regeneration condition of Comparative Example 1 is Joule heating (90°C) desorption, and the regeneration energy consumption is 1.2 GJ / tCO2; the regeneration condition of Comparative Example 2 is conventional steam purging, and the regeneration energy consumption is 1.5 GJ / tCO2; it can be seen that the regeneration energy consumption of the present invention is low, reducing energy consumption.

[0064] Experimental Example 3

[0065] Airborne carbon capture experiment: The solid waste graphite-based charged adsorbent prepared in Example 1, the graphite-based charged adsorbent prepared in Comparative Example 1, and the solid waste graphite in Comparative Example 2 were degassed under vacuum at 100°C for 15 hours to remove residual moisture and impurities. Then, 400ppm CO2 was introduced at 30°C to simulate dry air adsorption, followed by desorption at 100% N2 and 100°C. The CO2 adsorption performance of the adsorbent at ultra-low concentrations was tested. The experimental results are as follows: Figure 6 As shown, the adsorption capacity of the solid waste graphite-based base charged adsorbent prepared in Example 1 is stable at around 0.6 mmol / g, which is far superior to that of Comparative Examples 1-2.

[0066] Experimental Example 4

[0067] Cyclic Experiment: The solid waste graphite-based base charged adsorbent prepared in Example 1 was degassed under vacuum at 100°C for 15 hours to remove residual moisture and impurities. Then, CO2 adsorption was performed at 25°C for 20 minutes, followed by CO2 desorption at 100°C for 20 minutes. This process was repeated 100 times. The results are as follows: Figure 6 As shown, after 100 cycles, the graphite-based base charged adsorbent for solid waste still retains 95% of its capacity, demonstrating excellent stability.

[0068] Although specific embodiments of the present invention have been described in detail with reference to examples, they should not be construed as limiting the scope of protection of this patent. Various modifications and variations that can be made by those skilled in the art without inventive effort within the scope described in the claims are still within the scope of protection of this patent.

Claims

1. A method for preparing a graphite-based base charged adsorbent for solid waste, characterized in that, Includes the following steps: S1: Pickle the solid waste graphite, then place the pickled solid waste graphite in an inert gas atmosphere and keep it at 750~850℃ for 2~3h. After the heat preservation is completed, grind it into powder with a particle size ≤50μm to obtain pretreated solid waste graphite. S2: Mix pretreated solid waste graphite and CaCO3, then add H2O2 and stir evenly to obtain a composite slurry; S3: The composite slurry is molded into a film of 0.2~0.3mm, and the film is vacuum dried at 100℃ for 24h and then cut into graphite electrode sheets; S4: In the electrolyte, a graphite electrode sheet is used as the working electrode, Pt is used as the counter electrode, and SCE is used as the reference electrode to charge the solid waste graphite-based base charged adsorbent. The pickling process involves soaking solid waste graphite in 20% hydrochloric acid for 10-20 minutes; the grinding process involves ball milling the solid waste graphite at a speed of 300-500 r / min; and the charging process involves constant voltage charging at 2V for 2 hours or pulse charging at 0.5V with 10-minute intervals for 2 hours.

2. The method for preparing the solid waste graphite-based base charged adsorbent according to claim 1, characterized in that: The mass ratio of graphite to CaCO3 in the pretreated solid waste is 1:2~5.

3. The method for preparing the solid waste graphite-based base charged adsorbent according to claim 1, characterized in that: The material ratio of the pretreated solid waste graphite and CaCO3 mixture to H2O2 is 1g:1~3mL.

4. The method for preparing the solid waste graphite-based base charged adsorbent according to claim 1, characterized in that: The electrolyte is a KOH solution or a NaHCO3 solution.

5. The solid waste graphite-based charged adsorbent prepared by the method of any one of claims 1 to 4.

6. The application of the solid waste graphite-based base charged adsorbent according to claim 5 in air carbon capture.

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