Method for carbon sequestration and emission reduction in soil

Abstract

The application provides a soil carbon fixation and emission reduction method, comprising the following steps: mixing biomass, a flame retardant and water to activate the biomass, to obtain biomass activation product; pyrolyzing and carbonizing the biomass activation product, to obtain biochar precursor after cooling; processing the biochar precursor to have a particle size less than or equal to 300 nm, to obtain biochar; laying the biochar on a soil surface layer to obtain a biochar covering layer with a thickness of 1.0-1.5 cm; and plowing a surface soil layer with a depth of 0-20 cm to mix the surface soil layer with the biochar covering layer. The particle size of the biochar prepared by the application is small, i.e. less than or equal to 300 nm, so the biochar has a large specific surface area, and when the biochar with small particle size is applied to soil, the emission of soil CO2 can be significantly reduced, so that the carbon fixation and emission reduction effect of the biochar is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of carbon sequestration and emission reduction, and in particular to a method for soil carbon sequestration and emission reduction. BACKGROUND

[0002] Soil carbon pool is the largest and most active carbon pool in the terrestrial ecosystem, accounting for about one-third of the global carbon storage, and is the main carbon source of atmospheric greenhouse gases. The huge carbon capacity and natural carbon sequestration of soil have an important impact on the storage or release of carbon in the atmosphere. The increase of soil carbon emission leads to the increase of atmospheric carbon dioxide (CO2) concentration, which aggravates global climate warming; on the contrary, the increase of soil carbon pool can slow down the impact of climate change and has a positive regulating effect on climate change. Therefore, protecting and improving soil carbon pool is one of the important measures to cope with climate change.

[0003] Biochar is prepared by pyrolysis and carbonization of biomass at high temperature (300℃-450℃). Among them, biochar as an important material for soil CO2 emission reduction and carbon sink has been applied to protect and improve soil carbon pool. However, the existing biochar has poor carbon sequestration and emission reduction effect. SUMMARY

[0004] Therefore, it is necessary to provide a method for soil carbon sequestration and emission reduction which can improve the carbon sequestration and emission reduction effect of biochar.

[0005] At least one embodiment of the present application provides a method for soil carbon sequestration and emission reduction, comprising the following steps:

[0006] preparing biochar with a particle size less than or equal to 300 nm; and

[0007] applying the biochar to soil.

[0008] In some embodiments, the method for preparing the biochar comprises the following steps:

[0009] mixing biomass, a flame retardant and water to activate the biomass, to obtain biomass activation product;

[0010] pyrolyzing and carbonizing the biomass activation product to obtain biochar precursor after cooling; and

[0011] processing the biochar precursor to have a particle size less than or equal to 300 nm to obtain the biochar.

[0012] In some embodiments, the mass ratio of the biomass to the flame retardant is 1:1-4:1.

[0013] In some embodiments, the method comprises at least one of the following (1)-(2):

[0014] (1) the temperature for activating the biomass is 75-95 DEG C;

[0015] (2) the time for activating the biomass is 8-12 hours.

[0016] In some embodiments, the flame retardant comprises at least one of zinc borate and silicon dioxide.

[0017] In some embodiments, the method comprises at least one of the following (3)-(4):

[0018] (3) the temperature for pyrolysis carbonization is 100-120 DEG C;

[0019] (4) the time for pyrolysis carbonization is 40-60 minutes.

[0020] In some embodiments, the processing of the biochar precursor comprises the following steps:

[0021] The biochar precursor is processed by a ball mill.

[0022] In some embodiments, before mixing the biomass, the flame retardant and water, the method further comprises the step of crushing the biomass.

[0023] In some embodiments, the moisture content of the biomass is 5-10%.

[0024] In some embodiments, the application of the biochar to the soil comprises the following steps:

[0025] The biochar is spread on the surface layer of the soil to form a biochar cover layer with a thickness of 1-1.5 cm; and

[0026] The surface layer soil with a depth of 0-20 cm is ploughed to mix the surface layer soil with the biochar cover layer.

[0027] The biochar prepared by the present application has a small particle size, i.e. the particle size is less than or equal to 300 nm. Compared with biochar with large particle size, the biochar prepared by the present application has a larger specific surface area, stronger adsorption capacity and longer stability. When the biochar with small particle size is applied to the soil, the emission of CO2 from the soil can be significantly reduced, thereby improving the carbon sequestration and emission reduction effect of the biochar. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 A flow chart of the method for carbon sequestration and emission reduction of soil according to an embodiment of the present application;

[0029] Figure 2 A particle size distribution diagram of the biochar prepared in Example 1 of the present application. Detailed Implementation

[0030] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0032] Please see Figure 1 The present invention provides at least one embodiment of a method for soil carbon sequestration and emission reduction, comprising the following steps:

[0033] Step S11: Provide biomass and crush the biomass.

[0034] Specifically, the biomass with a moisture content of 5% to 10% is provided, and the biomass with a moisture content of 5% to 10% is crushed using a crusher.

[0035] For example, the moisture content of the biomass may be 5%, 6%, 7%, 8%, 9%, or 10%.

[0036] In one embodiment, the biomass includes plants. In one embodiment, the plants include trees, shrubs, vines, grasses, ferns, green algae, and lichens. In one embodiment, the trees include fruit trees.

[0037] Step S12: Mix the crushed biomass, flame retardant and water to activate the crushed biomass and obtain biomass activated product.

[0038] Specifically, the crushed biomass and the flame retardant are mixed in a mass ratio of 1:1 to 4:1, then water is added and mixed thoroughly to activate the crushed biomass with the flame retardant, thus obtaining the activated biomass. The crushed biomass is then impregnated with the flame retardant.

[0039] In one embodiment, the temperature for activating the biomass can be 75°C to 95°C. For example, the temperature for activating the biomass can be 75°C, 80°C, 85°C, 90°C, or 95°C.

[0040] In an embodiment, the time for activating the biomass can be 8h-12h. For example, the time for activating the biomass can be 8h, 9h, 10h, 11h or 12h.

[0041] In an embodiment, the flame retardant comprises at least one of zinc borate and silicon dioxide. In an embodiment, the silicon dioxide is nano-silicon dioxide.

[0042] In an embodiment, the mixture containing the broken biomass, the flame retardant and water after being stirred uniformly can be placed in a muffle furnace for activation. It can be understood that the temperature in the muffle furnace can be 75℃-95℃, and the time for placing the mixture in the muffle furnace can be 8h-12h.

[0043] The biomass activator has a lower pyrolysis carbonization temperature, i.e. 100℃-120℃, while the pyrolysis carbonization temperature of the biomass not activated by the flame retardant is as high as 300℃-450℃. That is, the flame retardant in the present application can reduce the pyrolysis carbonization temperature of the biomass, thereby being beneficial to energy saving and environmental protection.

[0044] Step S13, pyrolysis carbonization of the biomass activator to obtain a biochar precursor after cooling.

[0045] Specifically, the biomass activator is placed in a muffle furnace for pyrolysis carbonization to obtain the biochar precursor after cooling.

[0046] In an embodiment, the temperature for pyrolysis carbonization can be 100℃-120℃. For example, the temperature for pyrolysis carbonization can be 100℃, 105℃, 110℃, 115℃ or 120℃.

[0047] In an embodiment, the time for pyrolysis carbonization can be 40min-60min. For example, the time for pyrolysis carbonization can be 40min, 45min, 50min, 55min or 60min.

[0048] Step S14, treatment of the biochar precursor to have a particle size less than or equal to 300nm to obtain a biochar.

[0049] Specifically, the ball mill is used to treat the biochar precursor to reduce the particle size of the biochar precursor to obtain the biochar having a particle size less than or equal to 300nm.

[0050] The biochar has a large specific surface area due to the small particle size of the biochar. In addition, the biochar has a porous structure and good adsorption, provides a large specific surface area for biochemical reactions in the soil, and can provide more ecological niches and biochemical reaction active sites for microorganisms, which is beneficial to improve the carbon utilization efficiency of microorganisms and reduce the emission of CO2 in the soil.

[0051] It should be noted that the present application does not limit the use of a ball mill to treat the biochar precursor, and any method that can reduce the particle size of the biochar precursor can be used.

[0052] Step S15, applying the biochar to the soil.

[0053] Specifically, the biochar is laid flat on the surface layer of the soil to obtain a biochar cover layer with a thickness of 1.0-1.5 cm, and the soil is irrigated to soak the biochar cover layer, and then the surface layer soil with a depth of 0-20 cm is plowed to mix the surface layer soil with the biochar cover layer.

[0054] In an embodiment, the soil can be farmland soil, forest land soil or wetland soil.

[0055] The particle size of the biochar prepared by the present application is small, i.e. less than or equal to 300 nm. Compared with biochar with large particle size, the biochar prepared by the present application has a larger specific surface area, stronger adsorption capacity and longer stability. When the biochar with small particle size is applied to the soil, it can significantly reduce the emission of CO2 in the soil, thereby improving the carbon sequestration and emission reduction effect of the biochar, improving soil fertility, increasing the nitrogen and phosphorus content of the soil, and reducing soil acidity. The biochar in the present application can be widely used in farmland, forest land and wetland soil improvement, and promote ecological environment restoration.

[0056] In addition, the present application activates the biomass with the flame retardant to obtain the biomass activation product, which has a lower pyrolysis carbonization temperature, i.e. 100-120℃, while the pyrolysis carbonization temperature of biomass not activated by the flame retardant is as high as 300-450℃. That is, the flame retardant in the present application can reduce the pyrolysis carbonization temperature of the biomass, thereby being beneficial to energy saving and environmental protection.

[0057] The present application is further illustrated by specific examples and comparative examples.

[0058] Example 1

[0059] (1) The fruit trees are naturally air-dried to reduce the moisture content to 8%, and the air-dried fruit trees are crushed.

[0060] (2) The crushed fruit wood and zinc borate were mixed in a mass ratio of 1:1, then mixed with water and stirred evenly. The mixture was then soaked at 85°C for 8 hours to obtain the fruit wood activator.

[0061] (3) The activated fruit wood was placed in a muffle furnace at 105°C for pyrolysis and carbonization, and kept for 40 minutes. After cooling, the biochar precursor was obtained.

[0062] (4) The biochar precursor was ground using a ball mill to obtain biochar.

[0063] (5) Apply biochar to the soil surface of the five potted plants, so that the biochar is spread evenly on the soil surface of the five potted plants to obtain a biochar covering layer with a thickness of 1cm. Water the five potted plants to moisten the soil and biochar covering layer. Then, till the top soil with a depth of 0-20cm to mix the top soil with the biochar covering layer.

[0064] Comparative Example 1

[0065] (1) Water each of the five potted plants to moisten the soil, and then till the top layer of soil to a depth of 0-20cm.

[0066] Comparative Example 2

[0067] (1) Apply biochar with a particle size greater than 10 mm to the soil surface of 5 potted plants, so that the biochar is spread evenly on the soil surface of 5 potted plants to obtain a biochar covering layer with a thickness of 1 cm. Water the 5 potted plants to moisten the soil and biochar covering layer. Then, till the top layer of soil with a depth of 0-20 cm to mix the top layer of soil with the biochar covering layer.

[0068] (a) The particle size of the biochar prepared in Example 1 was tested.

[0069] Please see Figure 2 ,Depend on Figure 2 It can be seen that the peak particle size of the biochar prepared in Example 1 is 206.5 nm. That is to say, most of the biochar prepared in Example 1 has a particle size of 206.5 nm. Furthermore, from... Figure 2 It can also be concluded that the average particle size of all biochar prepared in Example 1 is 211.2 nm. This indicates that the particle size of most of the biochar prepared in Example 1 is ≤300 nm.

[0070] (ii) On the 10th, 43rd, 100th and 298th days after the application of biochar, the CO2 emissions from the soil of the five potted plants in Example 1 and Comparative Examples 1-2 were measured using a soil respiration monitor.

[0071] wherein the five pots in Example 1 and Comparative Examples 1-2 are respectively named as Pot 1, Pot 2, Pot 3, Pot 4 and Pot 5.

[0072] Table 1 shows the soil CO2 emission of the five pots in Example 1 and Comparative Examples 1-2 at the 10th day, the 43rd day, the 100th day and the 298th day after the biochar application

[0073]

[0074]

[0075] wherein the unit of the soil CO2 emission in Table 1 is mg / (m 2 ·h). For example, in Example 1, at the 10th day after the biochar application, the soil CO2 emission of the first pot is 73.51 mg / (m 2 ·h), the soil CO2 emission of the second pot is 81.45 mg / (m 2 ·h), the soil CO2 emission of the third pot is 74.32 mg / (m 2 ·h), the soil CO2 emission of the fourth pot is 69.49 mg / (m 2 ·h), the soil CO2 emission of the fifth pot is 58.20 mg / (m 2 ·h), and the average soil CO2 emission of the five pots is 71.40 mg / (m 2 ·h). In Comparative Example 1, at the 10th day after the soil surface was ploughed (Comparative Example 1 did not apply biochar), the soil CO2 emission of the first pot is 60.09 mg / (m 2 ·h), the soil CO2 emission of the second pot is 88.26 mg / (m 2 ·h), the soil CO2 emission of the third pot is 113.80 mg / (m 2 ·h), the soil CO2 emission of the fourth pot is 104.40 mg / (m 2 ·h), the soil CO2 emission of the fifth pot is 114.94 mg / (m 2 ·h), and the average soil CO2 emission of the five pots is 96.30 mg / (m 2 ·h). The average soil CO2 emission of the five pots in Example 1 is 25.86% lower than that in Comparative Example 1. The other data in Table 1 are described above and will not be described in detail here.

[0076] As shown in Table 1, the potting soil CO2 emissions of Example 1 (applying biochar) are reduced by 25.86%, 35.02%, 36.87% and 13.65% respectively, and the average reduction is 27.85% compared with Comparative Example 1 (not applying biochar) at the 10th day, the 43rd day, the 100th day and the 298th day; the potting soil CO2 emissions of Example 1 (applying biochar with a particle size of less than or equal to 300 nm) are reduced by 20.13%, 8.61%, 22.39% and 10.39% respectively, and the average reduction is 15.38% compared with Comparative Example 2 (applying biochar with a particle size of greater than 10 mm). It can be proved that the biochar with a small particle size can significantly reduce the emission of soil CO2.

[0077] The biochar prepared by the application has a small particle size, i.e., the particle size is less than or equal to 300 nm, and has a larger specific surface area, a stronger adsorption capacity and a longer stability compared with biochar with a large particle size. When the biochar with a small particle size is applied to soil, the emission of soil CO2 can be significantly reduced, thereby improving the carbon sequestration and emission reduction effect of the biochar, improving soil fertility, increasing the nitrogen and phosphorus content of soil, and reducing soil acidity. The biochar can be widely applied to farmland, woodland and wetland soil improvement, and promote ecological environment restoration.

[0078] In addition, the biomass is activated by the flame retardant to obtain the biomass activation product, and the biomass activation product has a lower pyrolysis carbonization temperature, i.e., only 100-120℃, while the pyrolysis carbonization temperature of biomass not activated by the flame retardant is as high as 300-450℃. That is, the flame retardant in the application can reduce the pyrolysis carbonization temperature of the biomass, thereby being beneficial to energy saving and environmental protection.

[0079] The technical features of the above-described embodiments can be combined arbitrarily, and for the sake of brevity, all possible combinations of the technical features in the above-described embodiments are not described, however, as long as the combinations of the technical features do not exist contradictory, they should be considered as the scope of the description.

[0080] The above-described embodiments only express several embodiments of the application, the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the application, a number of variations and improvements can be made, which are within the scope of the application. Therefore, the protection scope of the patent of the application should be subject to the appended claims.

Claims

1. A method for carbon sequestration and emission reduction of soil, characterized in that, The method comprises the following steps: preparing biochar with a particle size of less than or equal to 300 nm; and applying the biochar to soil; The method for preparing the biochar comprises the following steps: providing biomass with a water content of 5% to 10%, crushing the biomass with a water content of 5% to 10% using a crusher; mixing the crushed biomass, a flame retardant, and water to activate the crushed biomass, thereby obtaining biomass activation product; pyrolyzing and carbonizing the biomass activation product at a temperature of 100°C to 120°C for 40 min to 60 min, and obtaining biochar precursor after cooling; and processing the biochar precursor to have a particle size of less than or equal to 300 nm, thereby obtaining the biochar.

2. The method of carbon sequestration and emission reduction of soil according to claim 1, wherein, The mass ratio of the biomass to the flame retardant is 1:1 to 4:

1.

3. The method of carbon sequestration and emission reduction of soil according to claim 1, wherein, The method comprises at least one of the following (1) to (2): (1) the temperature for activating the biomass is 75°C to 95°C; (2) the time for activating the biomass is 8 h to 12 h.

4. The method of carbon sequestration and emission reduction of soil according to claim 1, wherein, The flame retardant comprises at least one of zinc borate and silicon dioxide.

5. The method of carbon sequestration and emission reduction of soil according to claim 1, wherein, Processing the biochar precursor comprises the following steps: processing the biochar precursor using a ball mill.

6. The method of soil carbon sequestration emission reduction according to any one of claims 1 to 5, characterized in that, Applying the biochar to soil comprises the following steps: laying the biochar flat on the surface layer of soil to obtain a biochar cover layer with a thickness of 1 cm to 1.5 cm; and plowing the surface layer soil with a depth of 0 to 20 cm to mix the surface layer soil with the biochar cover layer.

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