Methane emission inhibitor for'rice + 'rotation farmland as well as preparation method and application of methane emission inhibitor
By preparing a high-oxidation-state iron-carbon composite material from waste self-heating patches, the problem of high cost of methane emission inhibitors in paddy fields was solved, achieving low-cost and side-effect-free methane emission reduction in paddy fields.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- NINGBO UNIV
- Filing Date
- 2025-11-21
- Publication Date
- 2026-04-24
AI Technical Summary
In existing technologies, the production cost of rice paddy methane emission inhibitors is relatively high, and exogenous electron acceptor materials may have side effects on the soil, making long-term application difficult.
Using waste self-heating patches as raw materials, a high oxidation state iron-carbon composite material was prepared by grinding, ultrasonic water washing and hydrogen peroxide treatment. As a methane emission inhibitor in paddy fields, it utilizes its high oxidation state characteristics to inhibit the metabolic activity of methanogenic bacteria and adsorb soluble organic matter.
The preparation method is simple and low-cost, applicable to various paddy soils, has no side effects with long-term use, significantly reduces methane emissions, and reduces other greenhouse gas emissions.
Smart Images
Figure CN121914733A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of environmental protection technology, specifically to the control of methane emissions from rice-plus rotation farmland, and more specifically to a method and application for regulating methane generation and emissions from rice-plus rotation farmland. Background Technology
[0002] Methane (CH4) is the second largest greenhouse gas globally after carbon dioxide, but its greenhouse effect is 20 to 30 times greater. Studies show that reducing methane emissions is key to mitigating global warming. Rice paddies are a significant source of methane emissions, accounting for approximately 11% of global anthropogenic methane emissions. It is estimated that the total amount of methane escaping from rice paddies globally each year is as high as 0.25 to 1.0 billion tons. my country is the world's largest producer and consumer of rice, with over 60% of its rice paddies being "rice+" rotation fields. There is an urgent need to develop low-cost, green, and efficient methane emission reduction technologies for "rice+" rotation fields.
[0003] Supplementing flooded soils with electron acceptors is also a common methane emission reduction measure. For example, adding ferric iron (iron oxide), manganese (manganese oxide), sulfur (sulfate), and nitrogen (nitrate) to saturated soil can promote the oxidation of soluble organic matter in the soil, thereby reducing the potential organic substrate for methanogenic bacteria and inhibiting methane production. However, the small amount of exogenously added electron acceptors is quickly depleted by soil organic matter, requiring multiple additions to prolong the methane emission reduction effect. This significantly increases the cost of methane emission reduction, and some materials may have considerable side effects on the soil. For example, excessive application of sulfate can lead to paddy soil acidification, resulting in soil quality deterioration. Iron oxide is a relatively safe electron acceptor; however, large-scale production is costly and cannot be applied long-term.
[0004] Therefore, there is a need to provide a low-cost methane emission inhibitor for rice-plus rotation farmland. Summary of the Invention
[0005] The technical problem to be solved by this invention is: how to reduce the production cost of methane emission inhibitors in "rice+" rotation farmland.
[0006] To address the aforementioned technical problems, the first aspect of this invention provides a method for preparing a methane emission inhibitor in "rice+" rotation farmland, comprising the following steps: S1: Recycle used self-heating patches, remove the contents and grind them into powder; S2: The powder obtained in step S1 is subjected to ultrasonic water washing to remove salt and impurities; S3: Soak the powder washed with water in step S2 in hydrogen peroxide solution to obtain the oxidized material; S4: The oxidized material obtained in grinding step S3 is used to obtain methane emission inhibitors from "rice+" rotation farmland.
[0007] Preferably, in step S1, the grinding process is a ball milling process, and the specific conditions of the ball milling process are as follows: the ball milling ambient temperature is 5~40℃; the single ball milling time is 0.5h, and after each ball milling for 0.5h, the process is stopped and cooled for 5~10min, and the cycle is repeated 5~10 times; the diameter of the grinding balls is 10~20mm, the mesh size of the sieve is greater than or equal to 100 mesh, and the ball milling speed is 150~400rpm.
[0008] Preferably, in step S2, the ultrasonic frequency of the ultrasonic water washing is 20~40kHz and the ultrasonic power is 50~500W.
[0009] Preferably, in step S3, the concentration of hydrogen peroxide in the hydrogen peroxide solution is 1% to 10%.
[0010] Preferably, in step S4, the grinding process is ball milling, and the specific conditions of the ball milling process are as follows: the ball milling ambient temperature is 5~40℃; the single ball milling time is 0.5h, and after each ball milling for 0.5h, the milling is stopped and cooled for 5~10min, and the cycle is repeated 5~10 times; the diameter of the grinding balls is 10~20mm, the mesh size of the sieve is greater than or equal to 100 mesh, and the ball milling speed is 150~400rpm.
[0011] This invention extracts and prepares a methane emission inhibitor from used self-heating patches through grinding, washing, and oxygenation. This methane emission inhibitor is a high-oxidation-state iron-carbon composite material that can increase the redox potential (Eh) of flooded soil, directly inhibiting the metabolic activity of methanogens and making it difficult for them to complete the reduction reaction required for methanogenesis. At the same time, the high-oxidation-state iron-carbon composite material adsorbs and fixes a large amount of soluble organic matter, reducing the potential organic substrate for methanogens. In addition, the high-oxidation-state iron-carbon composite material significantly inhibits the activity of methanogens by promoting the proliferation of iron-reducing bacteria and competing with methanogens for limited electron donors (such as acetic acid and H2) in an anaerobic environment.
[0012] The second aspect of the present invention provides a methane emission inhibitor for rice-rotation farmland, wherein the methane emission inhibitor for rice-rotation farmland is prepared by the preparation method described in the first aspect.
[0013] The third aspect of this invention provides an application of the methane emission inhibitor in the "rice+" rotation farmland described in the second aspect, specifically, applying the methane emission inhibitor in the "rice+" rotation farmland to the "rice+" rotation soil, especially to the methane emission reduction in flooded "rice+" rotation soil.
[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. The methane emission inhibitor for rice-rotation farmland provided by this invention is prepared using waste self-heating patches as raw materials. The raw materials are widely available and easy to obtain, and have the advantage of low cost. 2. The preparation method of the methane emission inhibitor in rice-rotation farmland provided by the present invention is simple. It can be prepared by only simple ball milling, ultrasonic water washing and oxidation steps. No complicated process or equipment is required and the product is easy to industrialize. 3. The "rice+" rotation farmland methane emission inhibitor provided by this invention is applicable to methane emission reduction in various types of land, with good effect and no side effects on the land, and is suitable for long-term use. Attached Figure Description
[0015] Figure 1 The images show the SEM scan and EDS spectrum of the high oxidation state Fe-C material in Example 1 of this invention. Figure 2 The results of the test on the performance of high oxidation state Fe-C material in reducing soluble organic matter in "rice+" rotation farmland in Example 2 of the present invention; Figure 3 The results of the test on reducing methane emissions using the high oxidation state Fe-C material in Example 3 of this invention; Figure 4 The results of the test on reducing carbon dioxide emissions using the high oxidation state Fe-C material in Example 4 of this invention; Figure 5 The results of the test on the reduction of nitrous oxide emissions by the high oxidation state Fe-C material in Example 5 of this invention; Figure 6 The results of the test on the reduction of total greenhouse gas emissions by the high oxidation state Fe-C material in Example 6 of the present invention are shown. Detailed Implementation
[0016] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described in detail below. It should be noted that the following embodiments are only used to illustrate the implementation methods and typical parameters of the present invention, and are not intended to limit the parameter range described in the present invention. Reasonable variations derived therefrom are still within the protection scope of the present invention.
[0017] It should be noted that the endpoints and any values of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of the various ranges, the endpoint values of the various ranges and individual point values, and individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.
[0018] As described in the background section, the current preparation cost of methane emission inhibitors for "rice+" rotation farmland using electron acceptor-high oxidized iron oxide composite materials is relatively high. Therefore, this invention provides a low-cost methane emission inhibitor for "rice+" rotation farmland, the preparation method of which includes the following steps: S1: Recycle used self-heating patches, remove the contents and grind them into powder; S2: The powder obtained in step S1 is subjected to ultrasonic water washing to remove salt and impurities; S3: Soak the powder washed with water in step S2 in hydrogen peroxide solution to obtain the oxidized material; S4: The oxidized material obtained in grinding step S3 is used to obtain methane emission inhibitors from "rice+" rotation farmland.
[0019] The above-described embodiments extract and prepare a high-oxidation-state iron-carbon composite material from used self-heating patches through grinding, washing, and oxygenation steps. This material can be used to suppress methane emissions from rice-plus rotation farmland. The method achieves resource utilization of waste self-heating patches through a three-step process, solving the problem of high raw material costs associated with traditional methods. By controlling the particle size of the material through a staged ball milling process, effectively removing impurities through ultrasonic washing, and oxygenating with hydrogen peroxide, a high-oxidation-state methane emission inhibitor with a high specific surface area is finally prepared.
[0020] In step S1 of the above embodiment, the grinding process is a ball milling process. The specific conditions of the ball milling process are as follows: the ball milling ambient temperature is 5~40℃; the single ball milling time is 0.5h, and after each ball milling for 0.5h, it is stopped and cooled for 5~10min, and the cycle is repeated 5~10 times; the diameter of the grinding ball is 10~20mm, the mesh size of the sieve is greater than or equal to 100 mesh, and the ball milling speed is 150~400rpm. Low-temperature intermittent ball milling can effectively prevent the material from overheating and agglomerating.
[0021] In step S2 of the above embodiment, the ultrasonic frequency of the ultrasonic water washing is 20~40kHz and the ultrasonic power is 50~500W.
[0022] In step S2 of the above embodiment, ultrasonic cleaning can remove impurities, salts and other organic substances from the contents of the self-heating patch, which is beneficial to improving the product quality of the final product, methane emission inhibitor, and eliminating the risk of soil salinization caused by exogenous materials. At the same time, the ultrasonic frequency of 20~40kHz is matched with 100-500W power to form the optimal cavitation effect, ensuring the cleaning effect while avoiding damage to the three-dimensional structure of the iron-based material caused by excessive power.
[0023] In step S3 of the above embodiment, the concentration of hydrogen peroxide in the hydrogen peroxide solution is 1% to 10%.
[0024] In step S4 of the above embodiment, the grinding process is a ball milling process. The specific conditions of the ball milling process are as follows: the ball milling ambient temperature is 5~40℃; the single ball milling time is 0.5h, and after each ball milling of 0.5h, it is stopped and cooled for 5~10min, and the cycle is repeated 5~10 times; the diameter of the grinding balls is 10~20mm, the mesh size of the sieve is greater than or equal to 100 mesh, and the ball milling speed is 150~400rpm. The ball milling process in step S4 can increase the specific surface area of the material, expose more Fe-O active sites and cavities, and enhance the methane emission reduction capacity of the final product.
[0025] The methane emission inhibitor for rice-plus rotation farmland prepared through the above-described embodiments is essentially a high-oxidation-state iron-carbon composite material, which can be used in rice-plus rotation farmland soils where methane production occurs under flooded conditions.
[0026] More specifically, this refers to rice-wheat, rice-vegetable, rice-oil, and rice-rice farmland soils that exhibit methanogenesis processes under the aforementioned flooding conditions.
[0027] The "rice+" rotation farmland emission inhibitor prepared using the above-described embodiments can effectively increase the redox potential of the flooded environment, inhibiting the metabolic activity of methanogenic bacteria and making it difficult for them to complete the reduction reaction required for methanogenesis. The "rice+" rotation farmland methane emission inhibitor prepared using the above-described embodiments can also effectively adsorb a large amount of soluble organic matter, reducing the organic substrate for methanogenic bacteria. Simultaneously, the "rice+" rotation farmland methane emission inhibitor provided by the above-described embodiments can act as an electron acceptor, driving the anaerobic oxidation process of methane. In this process, methanogenic bacteria can convert methane into carbon dioxide and reduce ferric iron to ferrous iron. This coupling reaction can significantly reduce the final methane emission. Furthermore, the "rice+" rotation farmland methane emission inhibitor prepared using the above-described embodiments can significantly inhibit the activity of methanogenic bacteria by promoting the proliferation of iron-reducing bacteria and competing with methanogenic bacteria for limited electron donors (such as acetic acid and H2) in an anaerobic environment. The combination of these multiple reactions can effectively reduce the methane emission of "rice+" rotation farmland under flooded conditions.
[0028] More specifically, the methane emission inhibitor for rice-plus rotation farmland prepared by the above embodiments includes the following components: 35%~45% iron (Fe), 5%~15% carbon (C), 20%~30% oxygen (O), with the balance being unavoidable impurities or common soil minerals.
[0029] More specifically, if the applicable environment is a paddy field, the depth of the "rice+" rotation farmland methane emission inhibitor prepared by the above implementation method in the soil is 0~20 cm, the mass ratio of the "rice+" rotation farmland methane emission inhibitor to the soil is (0.1~1):100, and the application environment is a flooded environment.
[0030] The technical solutions of the present invention are further described below through specific embodiments. Unless otherwise defined, all terms, symbols, and other scientific terms used herein are intended to have the same meaning as commonly understood by one of ordinary skill in the art. In some cases, terms with a conventional understanding are limited herein for clarification or ease of reference, and such limitations should not be construed as indicating a significant difference from the conventional understanding in the art. The technical methods described or referenced herein are generally well understood by those skilled in the art and have been adopted by conventional methods. Unless otherwise stated, the use of commercially available kits, reagents, and instruments shall be performed according to the manufacturer's instructions and parameters.
[0031] Example 1 Preparation of high oxidation state Fe-C materials S1: Recycle used self-heating patches. At 25℃, remove the contents of the used self-heating patches, with a mass of 10kg. Place the waste in a grinding jar and grind the contents using a ball mill at 300rpm for 0.5 hours. Stop grinding for 5 minutes to prevent the temperature of the grinding material from getting too high. Continue grinding for 0.5 hours, and repeat this grinding process for 3 hours. S2: Add ultrapure water to the powder obtained in step S1, and perform ultrasonic water washing in a 50W ultrasonic cleaner for 20 minutes. Repeat the washing twice to remove salt and impurities. S3: Immerse the Fe-C material cleaned in step S3 into a hydrogen peroxide solution for oxygenation. The concentration of hydrogen peroxide is 1%-10%, and the immersion time is controlled at 10-40 minutes. S4: The material obtained after oxygenation in step S3 is dried in a forced-air drying oven at 55°C for 24 hours. The dried material is then placed in a grinding jar and ball-milled at 300 rpm for 0.5 hours. The grinding is stopped for 5 minutes to prevent the temperature of the grinding material from getting too high. The grinding continues for another 0.5 hours. This grinding process is repeated for 3 hours. The grinding powder is then removed, passed through a 100-mesh sieve, and the material passing through the sieve is used to obtain a high oxidation state Fe-C material with an average particle size of 150 micrometers.
[0032] The Fe-C materials and high-oxidation-state Fe-C materials prepared in this embodiment were subjected to SEM scanning and EDS analysis. The relevant results are as follows: Figure 1 As shown, where, Figure 1 In the figure, A represents the SEM scan result of the Fe-C material. Figure 1 In the figure, B represents the SEM scan result of the high oxidation state Fe-C material, derived from... Figure 1The SEM results show that the high oxidation state Fe-C material prepared in this embodiment has a smooth and flat surface without grooves, and the particle size is relatively uniform and in regular block shape. The EDS results show that the Fe-C material includes Fe, C and O. Compared with the present invention, the O content in the high oxidation state Fe-C material prepared in this invention is increased by 77%, and the oxidation state is significantly improved.
[0033] Example 2 Test on the performance of high oxidized Fe-C materials in reducing soluble organic matter in soil of rice-plus rotation farmland Topsoil (0-20 cm) from typical "rice+" rotation farmland was collected, air-dried in a cool place, and stored for later use. Simulating paddy field conditions, 1.0 kg of paddy field soil and 1.0 g of high-oxidation-state Fe-C material were mixed and added to a 650 mL culture tank at a depth of 10 cm. During the 30-day culture period, soil pore water was collected periodically using a soil pore water sampler. The soil pore water was acidified with 1 M hydrochloric acid and stored for three-dimensional fluorescence analysis. The results are shown below. Figure 2 As shown, by Figure 2 This indicates that the high-oxidation-state Fe-C material not only significantly reduced the soluble organic carbon in the soil of rice-plus rotation farmland, but also changed the structure of the soluble organic carbon.
[0034] Example 3 Tests on reducing methane emissions using high oxidation state Fe-C materials High oxidation state Fe-C materials can significantly reduce CH4 emissions. For example... Figure 3 As shown in Figure A, after 40 days of cultivation with the addition of high-oxidation-state Fe-C material, compared to the blank control, methane emission rate was significantly suppressed from day 30 onwards, with the best effect observed on day 40. Figure 3 As shown in B, during the 40-day culture period, the methane emission inhibitors reduced the methane emission rate by 25.4% compared to the blank control.
[0035] Example 4 Tests on the reduction of carbon dioxide emissions by high oxidation state Fe-C materials High oxidation state Fe-C materials can significantly reduce CO2 emissions. For example... Figure 4 As shown in Figure A, after 40 days of cultivation with the addition of high-oxidation-state Fe-C material, the carbon dioxide emission rate was significantly suppressed from day 0 to day 10 compared to the blank control. Figure 4 As shown in B, during the 40-day cultivation process, the oxidized Fe-C material reduced the carbon dioxide emission rate by 44.9% compared to the blank control.
[0036] Example 5 Tests on reducing nitrous oxide emissions using high oxidation state Fe-C materials High oxidation state Fe-C materials can reduce N2O emissions to some extent. For example... Figure 5 As shown in Figure A, after 40 days of cultivation with the addition of high-oxidation-state Fe-C material, compared to the blank control, the nitrous oxide emission rate was significantly suppressed from day 6, with the best effect observed on day 10, followed by a decrease. Figure 5 As shown in B, during the 40-day cultivation process, the high-oxidation-state Fe-C material reduced the nitrous oxide emission rate by 36.1% compared to the blank control.
[0037] Example 6 High-oxidation-state Fe-C materials reduce total greenhouse gas emissions from rice-plus rotation farmland. like Figure 6 As shown in Figure A, the field experiment was conducted in the rice-wheat rotation experimental field in Yinzhou District, Ningbo. The experiment used the Yongyou 15 rice variety and included a blank control without high-oxidized-state Fe-C material and a treatment with high-oxidized-state Fe-C material. Before transplanting rice seedlings after soil tillage, high-oxidized-state Fe-C material was evenly applied to the top 20cm of soil at a dosage of 9 t / ha. After transplanting, a static box with an openable lid, equipped with a thermometer and barometer, was set up in the field to monitor changes in field temperature and pressure. The box was normally opened for ventilation, allowing the rice to grow in a normal field environment. Gas samples were taken during the application of high-oxidized-state Fe-C material and at the peak tillering stage of rice (40 days after transplanting) to test changes in field humidity and greenhouse gas concentrations. Figure 6 As shown in B, the average temperature over a day decreased by 0.02% compared to the control group; Figure 6 As shown in C, the average humidity over a day increased by 0.01% compared to the control group; Figure 6 As shown in D, the average air pressure over a day decreased by 0.01% compared to the control group; Figure 6 As shown in E, the average daily CO2 concentration decreased by 1.37% compared to the blank control; Figure 6 As shown in F, the average concentration of N2O within a day remained almost unchanged compared to the blank control; Figure 6 As shown in G, the average concentration of CH4 within one day decreased by 11.9% compared to the blank control; as Figure 6 As shown by H in the figure, the average concentration of total greenhouse gases (calculated as CO2; total CO2 = CO2 + 28 * CH4 + 300 * N2O) within a day was reduced by 7.6% compared to the blank control. Field validation experiments demonstrated that the high-oxidation-state Fe-C material has a significant effect on reducing greenhouse gas emissions, especially methane. The high-oxidation-state Fe-C material provided by this invention can be widely used as a methane emission inhibitor in "rice+" rotation farmland.
[0038] While the disclosure is as stated above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of this disclosure, and all such changes and modifications will fall within the protection scope of this invention.
Claims
1. A method for preparing a methane emission inhibitor in "rice+" rotation farmland, characterized in that, Includes the following steps: S1: Recycle used self-heating patches, remove the contents and grind them into powder; S2: The powder obtained in step S1 is subjected to ultrasonic water washing to remove salt and impurities; S3: Soak the powder washed with water in step S2 in hydrogen peroxide solution to obtain the oxidized material; S4: The oxidized material obtained in grinding step S3 is used to obtain methane emission inhibitors from "rice+" rotation farmland.
2. The preparation method according to claim 1, characterized in that, In step S1, the grinding process is a ball milling process. The specific conditions of the ball milling process are as follows: the ball milling ambient temperature is 5~40℃; the single ball milling time is 0.5h, and after each ball milling for 0.5h, the milling is stopped and cooled for 5~10min, and the cycle is repeated 5~10 times; the diameter of the grinding balls is 10~20mm, the mesh size of the sieve is greater than or equal to 100 mesh, and the ball milling speed is 150~400rpm.
3. The preparation method according to claim 1, characterized in that, In step S2, the ultrasonic frequency of the ultrasonic water washing is 20~40kHz and the ultrasonic power is 50~500W.
4. The preparation method according to claim 1, characterized in that, In step S3, the concentration of hydrogen peroxide in the hydrogen peroxide solution is 1% to 10%.
5. The preparation method according to claim 1, characterized in that, In step S4, the grinding process is ball milling. The specific conditions of the ball milling process are as follows: the ball milling ambient temperature is 5~40℃; the single ball milling time is 0.5h, and after each ball milling for 0.5h, the milling is stopped and cooled for 5~10min, and the cycle is repeated 5~10 times; the diameter of the grinding balls is 10~20mm, the mesh size of the sieve is greater than or equal to 100 mesh, and the ball milling speed is 150~400rpm.
6. A methane emission inhibitor for "rice+" rotation farmland, characterized in that, The methane emission inhibitor in the "rice+" rotation farmland is prepared using any one of the preparation methods described in claims 1 to 5.
7. The application of the methane emission inhibitor in "rice+" rotation farmland as described in claim 6, characterized in that, The aforementioned methane emission inhibitor from the "rice+" rotation farmland was used for methane emission reduction in the "rice+" rotation soil.