A plant-based absorbent for CO2 absorption, its preparation method, and its application.

Abstract

This invention discloses a plant-based absorbent for absorbing CO2, its preparation method, and its application. This invention relates to the field of pollutant purification technology. The plant-based absorbent comprises plant extracts and chemical reagents; by weight, the plant extracts include 3-15 parts of acorn branch and leaf extract, 10-30 parts of *Gnaphalium affine* leaf extract, 5-30 parts of *Artemisia annua* branch and leaf extract, 5-10 parts of clover extract, and 15-25 parts of cypress branch and leaf extract; the chemical reagents include magnesium hydroxide or magnesium oxide, as well as zeolite, charcoal powder, and potassium hydroxide; the mass ratio of the plant extracts to the chemical reagents is 100:38-60. The CO2 absorbent provided by this invention has a good absorption effect on CO2, with an absorption capacity of 5.0-12.0 L (CO2) / 100 g (CO2 absorbent), and also features low cost, low energy consumption, high safety, and ease of use. Furthermore, this invention also provides a recyclable CO2 absorbent.

Description

Technical Field

[0001] This invention relates to the field of pollutant purification technology. More specifically, it relates to a plant-based absorbent for absorbing CO2, its preparation method, and its application. Background Technology

[0002] According to the International Energy Agency, global energy-related carbon dioxide emissions reached 37.4 billion tons in 2023, and emissions have been increasing in the past two years. With continued industrialization, carbon dioxide emissions have become a global concern and a subject of strict regulation.

[0003] Currently, industrial emission reduction technologies mainly employ carbon capture and utilization storage (CUSS) technology. CO2 capture methods are categorized into three types: pre-combustion, post-combustion, and oxy-fuel combustion. Among post-combustion CO2 capture methods, absorption is the most common. This process involves an absorption tower and a desorption tower. After desulfurization and denitrification, the flue gas enters the absorption tower from the bottom via an induced draft fan. Simultaneously, the absorbent is sprayed down from the top of the absorption tower. The flue gas and absorbent react upon contact within the tower, with the absorbent absorbing CO2 from the flue gas, becoming a CO2-rich solution. This rich solution is then pumped to the desorption tower, where it is heated to 100–120°C by a reboiler, causing it to decompose and release the CO2 absorbed from the flue gas, ultimately achieving carbon dioxide separation and recovery. Therefore, the performance of the absorbent is crucial for CO2 capture. Common chemical adsorbents include amine compounds and hot potassium hydroxide solutions. The advantages of chemical absorption are its high selectivity; it can efficiently capture carbon dioxide from complex gas mixtures, even at low concentrations, and its cost is relatively low compared to other methods. However, existing chemical absorption methods still suffer from problems such as low carbon dioxide absorption capacity, poor environmental friendliness, easy degradation of absorbents, and serious side reactions, or high energy consumption during desorption. Therefore, developing a new type of absorbent with high CO2 absorption capacity, low regeneration consumption, non-toxicity, low corrosiveness, low cost, and large-scale application in industrial production has become the key to solving the current carbon dioxide problem. Summary of the Invention

[0004] Based on the above-mentioned shortcomings, the first objective of this invention is to provide a plant-based absorbent for absorbing CO2. The plant-based absorbent provided by this invention exhibits good CO2 absorption, with an absorption capacity of 5.0-12.0 L (CO2) / 100 g (CO2 absorbent) in the absorbent. Furthermore, it features low cost, low energy consumption, high safety, and ease of use.

[0005] A second objective of this invention is to provide a method for preparing the plant absorbent liquid for absorbing CO2 as described above.

[0006] The third objective of this invention is to provide a recyclable plant absorbent for absorbing CO2. By improving the formulation of the previous CO2 absorbent, a recyclable absorbent that can both absorb and desorb CO2 is obtained, and energy consumption is reduced by more than 30% during the desorption process. This achieves a CO2 recycling system of capture-separation-capture, further reducing costs.

[0007] A fourth objective of this invention is to provide a method for preparing a recyclable plant absorbent liquid for absorbing CO2, as described above.

[0008] A fifth object of the present invention is to provide a biochemical scavenging solution comprising the plant absorbent liquid for absorbing CO2 as described above.

[0009] A sixth object of the present invention is to provide a biochemical scavenging solution comprising the recyclable plant absorbent liquid for absorbing CO2 as described above.

[0010] A seventh object of the present invention is to provide a CO2 removal device comprising the biochemical removal solution described above.

[0011] To achieve the first objective mentioned above, the present invention adopts the following technical solution:

[0012] This invention discloses a plant absorbent for absorbing CO2, wherein the plant absorbent for absorbing CO2 comprises a plant extract and a chemical reagent;

[0013] The plant extracts, by weight, include 3-15 parts of acorn branch and leaf extract, 10-30 parts of muskwort leaf extract, 5-30 parts of artemisia branch and leaf extract, 5-10 parts of clover extract, and 15-25 parts of cypress branch and leaf extract.

[0014] The chemical reagents include magnesium hydroxide or magnesium oxide, as well as zeolite, charcoal powder and potassium hydroxide;

[0015] The mass ratio of the plant extract to the chemical reagent is 100:38-60.

[0016] Furthermore, by weight, the chemical reagent comprises 10-15 parts magnesium hydroxide or magnesium oxide, 3-5 parts zeolite, 5-10 parts charcoal powder, and 20-30 parts potassium hydroxide.

[0017] To achieve the second objective mentioned above, the present invention adopts the following technical solution:

[0018] This invention discloses a method for preparing the plant absorbent liquid for absorbing CO2 as described above, comprising the following steps:

[0019] 1) Grind and crush each plant material, add the crushed plant material to water and heat to extract. The amount of water added is calculated as 100-2000 parts by weight (preferably 100-500 parts by weight) of water per 100 parts by weight of plant material. After the heating and extraction is completed, soak for 10-24 hours, filter to obtain the supernatant, mix and obtain the plant extract.

[0020] 2) Add each chemical reagent to the plant extract, wherein for every 100 parts by weight of plant extract, add 3-5 parts by weight of zeolite, 5-10 parts by weight of charcoal powder, 20-30 parts by weight of potassium hydroxide and 10-15 parts by weight of magnesium hydroxide or magnesium oxide to obtain the final product.

[0021] Furthermore, the extraction temperature is 100-120℃, and the extraction time is 0.5-2 hours.

[0022] Furthermore, the crushing process involves cutting the washed plant materials into small pieces or segments 1-2 cm long, soaking them in water for more than 10 hours, and then grinding them into a slurry.

[0023] To achieve the third objective mentioned above, the present invention adopts the following technical solution:

[0024] This invention discloses a recyclable plant absorbent for absorbing CO2, comprising plant extract and chemical reagents;

[0025] The plant extracts, by weight, include 3-15 parts of acorn branch and leaf extract, 10-30 parts of muskwort leaf extract, 5-30 parts of artemisia branch and leaf extract, 5-10 parts of clover extract, and 15-25 parts of cypress branch and leaf extract.

[0026] The chemical reagent includes monoethanolamine;

[0027] The mass ratio of the plant extract to the chemical reagent is 100:20-40.

[0028] By adjusting the chemical reagents, a cyclical operation of CO2 capture-separation-capture can be achieved. Since the formula of the plant extract that plays a major role in CO2 absorption remains unchanged, this CO2 absorbent solution not only ensures high CO2 absorption capacity but also further reduces CO2 absorbent solution loss and lowers costs.

[0029] Furthermore, the chemical reagent is 20-30 parts monoethanolamine by weight.

[0030] To achieve the fourth objective mentioned above, the present invention adopts the following technical solution:

[0031] This invention discloses a method for preparing a recyclable plant absorbent liquid for absorbing CO2 as described above, comprising the following steps:

[0032] 1) Grind and crush each plant material, add the crushed plant material to water and heat to extract. The amount of water added is calculated as 100-2000 parts by weight (preferably 100-500 parts by weight) of water per 100 parts by weight of plant material. After the heating and extraction is completed, soak for 10-24 hours, filter to obtain the supernatant, mix and obtain the plant extract.

[0033] 2) Add each chemical reagent to the plant extract, wherein 20-40 parts by weight of monoethanolamine are added to every 100 parts by weight of plant extract to obtain the final product.

[0034] Furthermore, the extraction temperature is 100-120℃, and the extraction time is 0.5-2 hours.

[0035] Furthermore, the crushing process involves cutting the washed plant materials into small pieces or segments 1-2 cm long, soaking them in water for more than 10 hours, and then grinding them into a slurry.

[0036] To achieve the fifth objective mentioned above, the present invention adopts the following technical solution:

[0037] This invention discloses a biochemical scavenging solution, including the plant absorption solution for absorbing CO2 as described above.

[0038] To achieve the sixth objective mentioned above, the present invention adopts the following technical solution:

[0039] This invention discloses a biochemical scavenging solution, comprising the recyclable plant absorbent for absorbing CO2 as described above.

[0040] To achieve the seventh objective mentioned above, the present invention adopts the following technical solution:

[0041] This invention discloses a CO2 removal device comprising the biochemical removal solution described above.

[0042] The beneficial effects of this invention are as follows:

[0043] This invention discloses a plant-based absorbent for absorbing CO2, its preparation method, and its applications. Compared to existing technologies, the technical solution of this invention has at least the following advantages:

[0044] (1) This invention selects safe and environmentally friendly plant extracts as the main component for CO2 absorption. It has low cost and high safety. Combined with common chemical reagents (such as zeolite, charcoal powder, potassium hydroxide and magnesium hydroxide or magnesium oxide), it can efficiently absorb CO2. The amount of CO2 absorbed in the CO2 absorption liquid is 5.0-12.0 L (CO2) / 100 g (CO2 absorption liquid). This absorbent can be used for simple CO2 absorption without CO2 separation. Therefore, from a process perspective, there is no need to set up a desorption tower, thus saving equipment investment and reducing energy consumption.

[0045] (2) In order to expand the applicability of CO2 absorbent, the chemical reagents were further adjusted. Monoethanolamine was used as a chemical reagent and combined with plant extract to realize the cyclic operation of CO2 capture-separation-capture. The experiment showed that the CO2 absorption capacity of the recyclable CO2 absorbent was 5.0-12.0 L (CO2) / 100 g (CO2 absorbent), the absorption and desorption rate reached 94%, the bottom temperature of the desorption tower was 95-98℃, and the average power consumption was 1.5 kW·h. The CO2 absorption and desorption rate was high. Therefore, the CO2 absorbent not only ensured the high absorption capacity of CO2, but also reduced the cost. Detailed Implementation

[0046] To more clearly illustrate the present invention, the following description, in conjunction with preferred embodiments, further clarifies the invention. It should be understood that the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0047] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0048] Example 1

[0049] Wash the acorn tree branches and leaves, cut them into small pieces or segments 1-2 cm long, and soak them in 20 times their weight of water for 12 hours. After soaking, grind them into a slurry, then put them back into the original soaking water and heat them over a low flame to 100-120°C for 1 hour. After turning off the heat, soak them for at least 10 hours to fully release the plant cell contents. Extract the supernatant to obtain the acorn tree branch and leaf extract. Using the same method, obtain the extracts of cotoneaster leaves, artemisia leaves, clover leaves, and cypress leaves. Mix the above extracts in a mass ratio of 1:3:3:1:2 to obtain plant extract I.

[0050] Add 5g of zeolite, 5g of charcoal powder, 30g of potassium hydroxide and 15g of magnesium hydroxide to 100g of plant extract I. After mixing evenly, a CO2 absorption solution is obtained.

[0051] Example 2

[0052] The preparation method of plant extract I is the same as in Example 1.

[0053] Add the above chemical reagents to every 100g of plant extract, adding 5g of zeolite, 5g of charcoal powder, 20g of potassium hydroxide and 15g of magnesium hydroxide. After mixing evenly, a CO2 absorption solution is obtained.

[0054] Example 3

[0055] The preparation method of plant extract I is the same as in Example 1.

[0056] Add the above chemical reagents to every 100g of plant extract, adding 20g of potassium hydroxide and 5g of magnesium hydroxide. After mixing evenly, a CO2 absorption solution is obtained.

[0057] Comparative Example 1

[0058] Add the above chemical reagents to every 100 grams of water, consisting of 5g of zeolite, 5g of charcoal powder, 30g of potassium hydroxide, and 15g of magnesium hydroxide. Mix thoroughly to obtain the CO2 absorption solution.

[0059] Comparative Example 2

[0060] The preparation process of acorn tree and leaf extract, muskwort leaf extract, and clover extract is the same as in Example 1. They are mixed in a mass ratio of 1:3:1 to obtain plant extract control solution I.

[0061] Add the above chemical reagents to every 100g of plant extract control solution I, adding 5g of zeolite, 5g of charcoal powder, 30g of potassium hydroxide and 15g of magnesium hydroxide. After mixing evenly, a CO2 absorption solution is obtained.

[0062] Example 4

[0063] The preparation method of plant extract I is the same as in Example 1.

[0064] The above chemical reagents were added to every 100g of plant extract with 30g of monoethanolamine, and the mixture was stirred to obtain the CO2 absorption solution.

[0065] Example 5

[0066] Wash the acorn tree branches and leaves, cut them into small pieces or segments 1-2 cm long, and soak them in 15 times their weight of water for 12 hours. After soaking, grind them into a mud-like consistency, then put them back into the original soaking water and heat them over a low flame to 100-120°C for 1 hour. After turning off the heat, soak them for at least 10 hours to fully release the plant cell contents. Extract the supernatant to obtain the acorn tree branch and leaf extract. Using the same method, obtain the extracts of cotoneaster leaves, artemisia leaves, clover leaves, and cypress leaves. Mix the above extracts in a mass ratio of 1:3:3:1:2 to obtain plant extract II.

[0067] The above chemical reagents were added to every 100g of plant extract II with 30g of monoethanolamine, and the mixture was stirred to obtain CO2 absorption solution.

[0068] Example 6

[0069] Wash the acorn tree branches and leaves, cut them into small pieces or segments 1-2 cm long, and soak them in 10 times their weight of water for 12 hours. After soaking, grind them into a mud-like consistency, then put them back into the original soaking water and heat them over a low flame to 100-120°C for 1 hour. After turning off the heat, soak them for at least 10 hours to fully release the plant cell contents. Extract the supernatant to obtain the acorn tree branch and leaf extract. Using the same method, obtain the extracts of cotoneaster leaves, artemisia leaves, clover leaves, and cypress leaves. Mix the above extracts in a mass ratio of 1:3:3:1:2 to obtain plant extract III.

[0070] The above chemical reagents were added to every 100g of plant extract III with 30g of monoethanolamine, and the mixture was stirred to obtain CO2 absorption solution.

[0071] Example 7

[0072] Wash the acorn tree branches and leaves, cut them into small pieces or segments 1-2 cm long, and soak them in 5 times their weight of water for 12 hours. After soaking, grind them into a mud-like consistency, then put them back into the original soaking water and heat them over a low flame to 100-120°C for 1 hour. After turning off the heat, soak them for at least 10 hours to fully release the plant cell contents. Extract the supernatant to obtain the acorn tree branch and leaf extract. Using the same method, obtain the extracts of cotoneaster leaves, artemisia leaves, clover leaves, and cypress leaves. Mix the above extracts in a mass ratio of 1:3:3:1:2 to obtain plant extract IV.

[0073] The above chemical reagents were added to every 100g of plant extract IV at a ratio of 30g monoethanolamine, and the mixture was stirred to obtain the CO2 absorption solution.

[0074] Verification test

[0075] The test was conducted by the laboratory of Dalian University of Technology, and the test information is as follows:

[0076] I. Determination of CO2 absorption capacity

[0077] 1. Main equipment used in the testing process:

[0078] 250ml three-necked flask;

[0079] Oil bath;

[0080] Equipped with condenser coils and a chilled water circulation pump;

[0081] Inlet metering—mass flow meter controller (MFC);

[0082] Gas output metering - wet flow meter (automatic counting).

[0083] 2. Test conditions:

[0084] The CO2 absorption solution to be tested was 100g, the CO2 input rate was 150ml / min, the input CO2 concentration was 99.90%, the absorption time was 100-120min, and the correction coefficient was 1.079.

[0085] 3. Testing methods:

[0086] 100g of the CO2 absorbent solution to be tested is placed into a 250ml flask, which is then placed in an oil bath. The inlet line, condenser (with exhaust connection), and thermocouple are inserted. The oil bath is stirred and the temperature is controlled at 40℃ (the temperature of the absorbent solution in the flask is 40℃). Cooling water is turned on, and a metered amount of carbon dioxide gas is introduced for the absorption experiment. The absorption time is 100-120 minutes. When the outflow rate is basically the same as the inflow rate after 10 minutes, the absorption is considered saturated.

[0087] 4. Test Data Recording and Processing:

[0088] Recordable data includes intake volume (controlled by mass flow meter), output volume (read by wet flow meter), and CO2 absorption liquid temperature change (detected by thermocouple).

[0089] CO2 absorption capacity = CO2 input rate * time * calibration coefficient - output volume (flow meter reading)

[0090] 5. Test Results:

[0091] The results are shown in Tables 1 and 2.

[0092] Table 1

[0093]

[0094] Note: The experiment in Comparative Example 1 could not be carried out due to crystal blockage.

[0095] in conclusion:

[0096] A comparison of Examples 1 and 2 revealed that the CO2 absorption capacity of the same plant extract varied with the addition of different chemical reagents. The adsorption of carbon dioxide was better when the chemical reagents included magnesium hydroxide or magnesium oxide, as well as zeolite, charcoal powder, and potassium hydroxide.

[0097] As shown in Comparative Example 1, under the same conditions, chemical reagents mixed in water easily form carbonate crystals during the experiment, clogging the tubing and preventing the experiment from proceeding. Later, mass spectrometry analysis of plant extract I revealed the presence of isophorone, acetaminophen, lauramide propylamine oxide, and complex terpene glycoside derivatives. These components can undergo organic reactions with CO2, and their absorption mechanism is completely different from that of alkaline substances dissolved in water, further demonstrating the effectiveness of the plant extract.

[0098] The comparison between Example 1 and Comparative Example 2 revealed that the CO2 absorption amount varied when the combination of plant extracts was different but the chemical reagents were the same. The adsorption effect of carbon dioxide was better when the plant extracts were prepared in a specific ratio of acorn branch and leaf extract, muskwort branch and leaf extract, artemisia branch and leaf extract, clover extract and cypress branch and leaf extract.

[0099] Table 2

[0100]

[0101] in conclusion:

[0102] Under the same conditions of plant extract, the higher the concentration of chemical reagents within a certain range, the greater the CO2 absorption.

[0103] Under the same chemical reagent conditions, the higher the concentration of plant extract within a certain range, the greater its CO2 absorption.

[0104] II. Continuous Absorption and Desorption Experiment

[0105] Introduction to experimental equipment:

[0106] 1CO2 Chemical Absorption and Desorption Continuous Testing Device

[0107] 1.1 Main Components of the Experimental System

[0108] The experimental platform occupies an area of ​​3.3 m². 2 The total height is 2.2 m.

[0109] The entire system includes an absorption tower and a desorption tower.

[0110] The utilities include two chilled water circulators and one thermal oil heating circulator.

[0111] The control system is PLC-controlled and automatically collects parameters such as temperature, pressure, and circulation rate.

[0112] 1.2 Experimental Procedure

[0113] CO2 gas enters the absorption tower through a gas flow meter, where it comes into countercurrent contact with the absorbent (i.e., the CO2 absorbent liquid in Example 4). After decarbonization, it is discharged into the atmosphere through a separator. The rich absorbent liquid, having absorbed all the CO2, flows out from the bottom of the absorption tower, is heated by a heat exchanger, and then sent to the desorption tower. Under the heat provided by the heat transfer oil, the rich absorbent liquid undergoes a reversible reaction, releasing carbon dioxide gas which is discharged through the gas flow meter, regenerating into a lean absorbent liquid. The lean absorbent liquid is cooled by a heat exchanger and a cooler before being sent back to the top of the absorption tower, thus achieving the regeneration and recycling of the absorbent.

[0114] 2. Specific Test Methods

[0115] 2.1 Solution preparation and gas preparation

[0116] The absorbent solution used in Example 4 was 15L.

[0117] Gas: CO2 content 99.9%, intake rate: 3L / min.

[0118] 2.2 Solution Cold Cycle

[0119] Close the rich liquid outlet valve at the bottom of the absorber and open the buffer tank.

[0120] Pour the absorbent into the buffer tank, open the outlet valve of the buffer tank, and start the rich liquid pump to add absorbent to the desorption tower.

[0121] When the absorbent liquid level in the desorption tower exceeds the heating coil, the lean liquid pump is turned on to add absorbent liquid into the absorption tower.

[0122] Once the absorbent liquid level in the absorption tower rises to the middle sight glass, open the rich liquid valve of the absorption tower and close the outlet valve of the buffer tank, allowing the absorbent liquid to circulate in the absorption tower and desorption tower through the lean liquid pump and the rich liquid pump.

[0123] During the circulation process, the lean liquid pump and the rich liquid pump are continuously adjusted until the liquid level in the absorption tower and the desorption tower tends to stabilize.

[0124] 2.3 Hot Start-up

[0125] Turn on two chilled water circulators and a heat transfer oil circulator to heat the absorbent in the desorption tower through the heat transfer oil until the desorption temperature or test temperature is reached.

[0126] Start the inlet flow meter controller to introduce CO2 gas (99.9%) into the CO2 capture system.

[0127] 2.4 Operating Condition Adjustment

[0128] When the desorption tower starts to regenerate CO2, it indicates that the system cycle has begun.

[0129] The temperature at the bottom of the desorption tower is adjusted by changing the set temperature of the heat transfer oil.

[0130] Circulating cooling water is used to ensure cooling effect.

[0131] The CO2 content is controlled by a mass flow meter.

[0132] 2.5 Test Data Recording

[0133] When the CO2 absorption and desorption efficiency reaches over 90%, the solution inflow and outflow are balanced, the amount of regenerated CO2 is stable for 60 minutes, and the system temperature changes smoothly, the operating conditions are considered to have reached stability. The operating data is recorded, and the power consumption is measured by the electricity meter.

[0134] 3 Experimental Results

[0135] 3.1 Data Acquisition

[0136] The runtime is the cumulative system time, recorded in hours.

[0137] The intake volume is the data displayed by the gas flow meter at the intake, recorded in L;

[0138] The desorbed gas volume is the data displayed by the gas flow meter at the outlet, recorded in L;

[0139] The absorption-desorption rate is the ratio of desorbed gas volume to inlet gas volume, calculated as % (%).

[0140] The desorption temperature is the data displayed by the thermometer at the bottom of the desorption tower; record the data in °C.

[0141] Total power consumption is the electrical power consumed for heating; record the data in kW·h.

[0142] Average power consumption is the electrical power consumed per hour for heating, calculated in kW·h.

[0143] 3.2 Results

[0144] The results are shown in Table 3.

[0145] Table 3

[0146]

[0147] Conclusion: The CO2 plant absorption liquid exhibits a CO2 absorption and desorption efficiency of over 94% and good stability during 102 hours of operation, with an average power consumption of 1.5 kW·h.

[0148] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A plant-based absorbent for absorbing CO2, characterized in that, Including plant extracts and chemical reagents; The plant extracts, by weight, include 3-15 parts of acorn branch and leaf extract, 10-30 parts of muskwort leaf extract, 5-30 parts of artemisia branch and leaf extract, 5-10 parts of clover extract, and 15-25 parts of cypress branch and leaf extract. The chemical reagents include magnesium hydroxide or magnesium oxide, as well as zeolite, charcoal powder and potassium hydroxide; The mass ratio of the plant extract to the chemical reagent is 100:38-60.

2. The plant absorbent liquid for absorbing CO2 according to claim 1, characterized in that, By weight, the chemical reagents include 10-15 parts magnesium hydroxide or magnesium oxide, 3-5 parts zeolite, 5-10 parts charcoal powder and 20-30 parts potassium hydroxide.

3. The method for preparing plant absorbent liquid for absorbing CO2 as described in claim 1 or 2, characterized in that, Includes the following steps: 1) Grind and crush each plant material, add the crushed plant material to water and heat to extract. The amount of water added is calculated as 100-2000 parts by weight of water for every 100 parts by weight of plant material. After the heating and extraction is completed, soak for 10-24 hours, filter to obtain the supernatant, mix and obtain the plant extract. 2) Add each chemical reagent to the plant extract, wherein for every 100 parts by weight of plant extract, add 3-5 parts by weight of zeolite, 5-10 parts by weight of charcoal powder, 20-30 parts by weight of potassium hydroxide and 10-15 parts by weight of magnesium hydroxide or magnesium oxide to obtain the final product.

4. The preparation method according to claim 3, characterized in that, The extraction temperature is 100-120℃, and the extraction time is 0.5-2 hours.

5. A plant-based absorbent for absorbing CO2, characterized in that, Including plant extracts and chemical reagents; The plant extracts, by weight, include 3-15 parts of acorn branch and leaf extract, 10-30 parts of muskwort leaf extract, 5-30 parts of artemisia branch and leaf extract, 5-10 parts of clover extract, and 15-25 parts of cypress branch and leaf extract. The chemical reagent includes monoethanolamine; The mass ratio of the plant extract to the chemical reagent is 100:20-40.

6. The method for preparing plant absorbent liquid for absorbing CO2 as described in claim 5, characterized in that, Includes the following steps: 1) Grind and crush each plant material, add the crushed plant material to water and heat to extract. The amount of water added is calculated as 100-2000 parts by weight of water for every 100 parts by weight of plant material. After the heating and extraction is completed, soak for 10-24 hours, filter to obtain the supernatant, mix and obtain the plant extract. 2) Add each chemical reagent to the plant extract, wherein 20-40 parts by weight of monoethanolamine are added to every 100 parts by weight of plant extract to obtain the final product.

7. The preparation method according to claim 6, characterized in that, The extraction temperature is 100-120℃, and the extraction time is 0.5-2 hours.

8. A biochemical cleaning solution, characterized in that, Includes the plant absorbent liquid for absorbing CO2 as described in claim 1 or 2.

9. A biochemical cleaning solution, characterized in that, Includes the plant absorbent liquid for absorbing CO2 as described in claim 5.

10. A CO2 removal device, characterized in that, Includes the biochemical removal solution as described in claim 8 or 9.

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