Dual-effect functional material for medicine and fertilizer, preparation method and application

Abstract

The present application relates to the technical field of agricultural controlled-release / slow-release fertilizer, and particularly relates to a pesticide-fertilizer dual-effect functional material, a preparation method and application. The pesticide-fertilizer dual-effect functional material comprises a fertilizer core and a shell layer. The fertilizer core is a fertilizer. The shell layer is arranged outside the fertilizer core. The shell layer comprises a polyurethane layer and a tobacco stem biochar layer loaded with herbicide arranged in sequence from inside to outside. The herbicide comprises quinclorac. The preparation method is used for preparing the pesticide-fertilizer dual-effect functional material. The application is the application of the pesticide-fertilizer dual-effect functional material in promoting crop growth. The present application can simultaneously have the long-acting slow-release effects of herbicide and fertilizer.

Description

Technical Field

[0001] This invention relates to the field of agricultural controlled-release / slow-release fertilizer technology, and in particular to a dual-function material for both pesticide and fertilizer, its preparation method, and its application. Background Technology

[0002] Excessive fertilization can easily lead to soil compaction and eutrophication of surface water. Currently, the solution to this problem is the use of controlled-release / slow-release coated fertilizers. Controlled-release / slow-release coated fertilizer technology significantly improves fertilizer utilization by optimizing the fertilizer release rate. As an important innovation in modern agricultural technology, the development and application of controlled-release / slow-release coated fertilizers have profound significance for global food security and sustainable ecological development.

[0003] Common controlled-release / slow-release coated fertilizers include polyurethane-coated fertilizers, which have attracted much attention due to their advantages such as strong designability of molecular structure, excellent film-forming properties, and mature preparation technology. In particular, in recent years, bio-based polyurethane coating materials prepared from natural raw materials such as vegetable oils, starch, cellulose, and lignin have been widely used in the preparation of controlled-release / slow-release fertilizers due to their low cost and easy biodegradability. However, natural bio-based materials have low purity and usually contain a large number of easily soluble small molecules; moreover, they are rich in oxygen-containing functional groups and have strong hydrophilicity, resulting in poor controlled-release / slow-release performance. Therefore, it is necessary to modify bio-based polyurethane-coated fertilizers to improve their controlled-release / slow-release performance. However, existing modification methods (such as grafting hydrophobic materials onto polyurethane to improve its hydrophobicity; or polymerizing modified polysiloxanes to improve its thermal stability) have problems with the controlled-release / slow-release performance of polyurethane-coated fertilizers, including uncontrollable improvement effects, complex processes, limited performance, and increased costs.

[0004] In addition, other factors affecting crop growth exist in actual agricultural scenarios, such as weeds that compete with crops for nutrients and hinder plant growth and development. However, common polyurethane-coated fertilizers cannot simultaneously possess the functions of both herbicides and controlled-release fertilizers, highlighting the urgent need to develop multifunctional fertilizers.

[0005] Therefore, it is necessary to provide a dual-function material for both herbicide and fertilizer, its preparation method, and its application to address the problems of uncontrollable improvement in the controlled-release / slow-release performance of polyurethane-coated fertilizers using existing modification methods, such as complex processes, limited performance, and rising costs. Furthermore, it is necessary to address the issue that existing polyurethane-coated fertilizers cannot simultaneously possess both herbicide and fertilizer controlled-release functions. Summary of the Invention

[0006] The purpose of this invention is to provide a dual-function material for both medicinal and fertilizer effects, its preparation method, and its application. The specific technical solution is as follows: In a first aspect, the present invention provides a dual-function material for both fertilizer and pesticide, comprising a fertilizer core and a shell layer; the fertilizer core is a fertilizer; the shell layer is disposed around the outside of the fertilizer core; the shell layer comprises a polyurethane layer and a tobacco stem biochar layer loaded with a herbicide, arranged sequentially from the inside to the outside; the herbicide comprises quinclorac acid.

[0007] Optionally, the fertilizer includes urea.

[0008] Optionally, the dual-effect fertilizer-pesticide material further includes a first sealing layer and a second sealing layer; the first sealing layer is disposed between the polyurethane layer and the herbicide-loaded tobacco biochar layer; the second sealing layer is disposed on the outside of the herbicide-loaded tobacco biochar layer; the first sealing layer includes a microcrystalline wax layer; the second sealing layer includes a microcrystalline wax layer.

[0009] In a second aspect, the present invention provides a method for preparing a dual-effect drug-fertilizer material, comprising: Step S1: Prepare the polyurethane layer by spin coating on the outer side of the fertilizer core; After the raw material components required for the polyurethane layer are mixed evenly, they are spin-coated onto the outer side of the fertilizer core to prepare a polyurethane prefabricated layer; after the polyurethane prefabricated layer is subjected to a first curing treatment, the polyurethane layer is obtained. Step S2: Spin-coating the outer side of the polyurethane layer to prepare the tobacco stem biochar layer loaded with herbicide, thereby obtaining the dual-effect pesticide-fertilizer material; After mixing the required amount of herbicide-loaded tobacco stem biochar for the herbicide-loaded layer, the mixture is then spin-coated onto the outer side of the polyurethane layer to prepare a pre-formed layer of herbicide-loaded tobacco stem biochar. The pre-formed layer of herbicide-loaded tobacco stem biochar is then subjected to a second curing treatment to obtain the herbicide-loaded tobacco stem biochar layer.

[0010] Optionally, in step S2, the method for obtaining the tobacco stem biochar includes: First, the dried tobacco stems are crushed and sieved through a 40-mesh screen to obtain sieved tobacco stem powder. Second, the tobacco stem powder, ferric citrate, and phosphoric acid solution are mixed in a mass ratio of 30:2.1~2.4:96~108 and then heat-treated to obtain pre-charred tobacco stems. Then, the pre-charred tobacco stems are naturally cooled and washed with water until the filtrate is clear. Subsequently, the filter residue is collected and dried a second time to obtain dried pre-charred tobacco stems. Finally, the dried pre-charred tobacco stems are sieved through a 100-mesh screen to obtain sieved tobacco stem biochar. The first drying process uses a drying temperature of 60±5℃ and a drying time of 24±2h. The heat treatment is performed in an air atmosphere, with a heating temperature of 280±5℃ and a heating time of 5±0.5h; the heating rate used in the heat treatment is 5±1℃ / min. The phosphoric acid solution comprises an aqueous solution of phosphoric acid with a mass concentration of 85%.

[0011] Optionally, in step S2, the method for obtaining the herbicide-loaded tobacco stem biochar includes: The tobacco stem biochar was added to a herbicide aqueous solution, mixed well, and then subjected to adsorption treatment to obtain the herbicide-loaded tobacco stem biochar. The concentration of the herbicide in the aqueous solution is 40 ± 1 mg / L; The mass ratio of the tobacco stem biochar to the volume ratio of the herbicide aqueous solution is 0.1 g: 800~1500 mL; The adsorption treatment was completed under shaking conditions, with a shaking speed of 150±5 rpm, an adsorption temperature of 25±2℃, and an adsorption time of 90±10 min. The mass of the herbicide-loaded tobacco stem biochar used in the second spin coating is 1:167~250 of the mass of the fertilizer core; The second spin coating uses a spin coating temperature of 80±5℃, a spin coating time of 10±3min, and a spin coating speed of 50±5rpm.

[0012] Optionally, in step S1, the raw material components required for the polyurethane layer include castor oil and polymethylene polyphenyl polyisocyanate in a mass ratio of 1.1 to 1.6:1. The preparation steps of the polyurethane preform layer include: The required amounts of castor oil and polymethylene polyphenyl polyisocyanate are placed separately and degassed under vacuum. The castor oil and polymethylene polyphenyl polyisocyanate are then alternately spin-coated onto the outside of the fertilizer core 3 to 8 times to prepare the polyurethane preform layer. The total mass of the castor oil and the polymethylene polyphenyl polyisocyanate used in the first spin coating is 6% to 10% of the mass of the fertilizer core; The first spin coating uses a spin coating temperature of 80±5℃, a spin coating time of 10±3min, and a spin coating speed of 50rpm. The vacuum degassing process uses a vacuum degassing temperature of 80±5℃ and a vacuum degassing time of 4~9min.

[0013] Optionally, the curing temperature for the first curing treatment is 80±5℃, and the curing time is 7~15min; The second curing process uses a curing temperature of 80.0±5℃ and a curing time of 7~15min.

[0014] Optionally, between step S1 and step S2, the process further includes applying microcrystalline wax to the outside of the polyurethane layer via a third spin coating to prepare a first sealing pre-layer; and then subjecting the first sealing pre-layer to a third curing treatment to obtain the first sealing layer. The spin coating process used in the third spin coating is a spin coating temperature of 80±5℃, a spin coating time of 10±3min, and a spin coating speed of 50±5rpm. The curing temperature for the third curing process is 80.0±5℃, and the curing time is 7~15min. The mass of the microcrystalline wax used in the third spin coating is 0.9% to 1.2% of the mass of the fertilizer core. After step S2, the process further includes spin-coating microcrystalline wax onto the outer side of the polyurethane layer to prepare a second sealing pre-layer; and then subjecting the second sealing pre-layer to a fourth curing treatment to obtain the second sealing layer. The spin coating process for the fourth spin coating is characterized by a spin coating temperature of 80±5℃, a spin coating time of 10±3min, and a spin coating speed of 50±5rpm. The curing temperature for the fourth curing process is 80.0±5℃, and the curing time is 7~15min. The mass of the microcrystalline wax used in the fourth spin coating is 0.9% to 1.2% of the mass of the fertilizer core.

[0015] In a third aspect, the present invention provides an application of a dual-effect pesticide and fertilizer material in promoting crop growth.

[0016] The application of the technical solution of the present invention has at least the following beneficial effects: (1) The present invention provides a dual-effect fertilizer-pesticide material comprising a fertilizer core, a polyurethane layer as an inner shell, and a tobacco stem biochar layer loaded with herbicides as an outer shell, capable of simultaneously providing both long-lasting and slow-release effects of herbicides and fertilizers. Specifically, the principle is that the dual-effect fertilizer-pesticide material provided by the present invention achieves long-lasting and slow-release effects of herbicides and fertilizers through the synergistic effects of physical adsorption-slow release, chemical bonding-slow release, and physical barrier-slow release. Specifically: Regarding physical adsorption-slow release, the physical adsorption principle is as follows: Tobacco stem biochar possesses abundant microporous and mesoporous structures and a large specific surface area, providing numerous physical adsorption sites for the herbicide quinclorac acid molecules. Quinclorac acid molecules can be trapped in the pore network and surface depressions of the tobacco stem biochar through van der Waals forces and pore-filling effects. The slow release principle is as follows: In the release medium (such as water or soil solution), the physically adsorbed quinclorac acid molecules must overcome the van der Waals forces between themselves and the pore walls of the tobacco stem biochar to desorb and enter the release medium, thus exerting the herbicide effect. Due to the strong confinement effect of the microporous and mesoporous structures on the tobacco stem biochar on the quinclorac acid molecules, the diffusion path is tortuous and circuitous, and the desorption rate is much lower than that in the free state. This makes the release of quinclorac acid from the tobacco stem biochar time-dependent, achieving the initial slow release effect of the herbicide.

[0017] In terms of chemical bonding and sustained release, hydrogen bonds can be formed between quinclorac acid and tobacco biochar, as well as between quinclorac acid and the polyurethane layer. Compared with physical adsorption, hydrogen bonds can further enhance the sustained-release efficacy of herbicides. Specifically, the principle of hydrogen bond formation between quinclorac acid and tobacco biochar is as follows: the surface of tobacco biochar is rich in hydroxyl (OH) and carboxyl (COOH) groups, while the quinclorac acid molecule contains a carboxyl (COOH) group and a quinoline ring nitrogen atom (N). This allows quinclorac acid and tobacco biochar to form a multi-type, multidentate coordination hydrogen bond network (such as the hydrogen bond between OH on the surface of tobacco biochar and COOH of quinclorac acid: OH···O; the hydrogen bond between COOH on the surface of tobacco biochar and N of the quinoline ring of quinclorac acid: OH···N; and the hydrogen bond between COOH of quinclorac acid and OH on the surface of tobacco biochar: OH···O). The strength of these hydrogen bonds is much greater than that of van der Waals forces (bond energy approximately 1040 kJ / mol), requiring a higher energy barrier to overcome for the desorption of quinclorac acid from tobacco biochar. The principle behind the formation of hydrogen bonds between quinclorac acid and the polyurethane layer is as follows: when herbicide-loaded tobacco biochar is embedded in the polyurethane layer, the quinoline ring and carboxylic acid groups in the quinclorac acid molecule readily form hydrogen bonds with the urethane (NHCOO) groups on the polyurethane segments. During the release of quinclorac acid, the quinclorac acid molecules undergo dynamic adsorption and desorption with the polyurethane segments along their outward diffusion path: hydrogen bonds are continuously formed and broken, significantly slowing down the net diffusion rate of quinclorac acid and enhancing its sustained-release effect. In addition, the hydroxyl groups in tobacco stem biochar react with the isocyanate groups in the polyurethane layer to form urethane bonds, which increases the chemical bonding strength between the tobacco stem biochar and the polyurethane layer, ensuring the bonding strength between the herbicide-loaded tobacco stem biochar layer and the polyurethane layer and preventing separation. Furthermore, tobacco stem biochar also contains abundant nutrients needed by plants and crops, such as potassium, which is beneficial to promoting plant and crop growth.

[0018] Regarding the physical barrier and slow release, the hydrogen bonds formed between quinclorac acid and tobacco biochar, and between quinclorac acid and the polyurethane layer, facilitate the formation of a more uniform and dense polyurethane layer (equivalent to an inner physical barrier). For fertilizer to be released from the fertilizer core to the outside, it must pass through the uniform and dense polyurethane layer. Inside the uniform and dense polyurethane layer, the free volume pores are small and tortuous, greatly extending the fertilizer diffusion path. According to Fick's diffusion law, diffusion flux is inversely proportional to diffusion path length. The uniform and dense polyurethane layer significantly reduces the effective diffusion coefficient, enhancing the slow-release effect of the fertilizer. Furthermore, the herbicide-loaded tobacco biochar layer (equivalent to an outer physical barrier) surrounding the polyurethane layer further reduces the fertilizer diffusion rate, enhancing the slow-release effect of the fertilizer. Furthermore, the hydrogen bonding that forms a uniform and dense polyurethane layer, along with the herbicide-loaded tobacco biochar layer surrounding the polyurethane layer, synergistically enhances the polyurethane layer's resistance to swelling and water erosion, maintaining constant diffusion resistance throughout the release cycle. This strengthens the fertilizer's slow-release effect, achieving a long-lasting slow-release effect. Additionally, the herbicide, through the action of both inner and outer physical barriers, also achieves a long-lasting slow-release effect.

[0019] (2) The preparation method of the dual-effect drug and fertilizer functional material provided by the present invention can combine low cost, environmental friendliness and relatively simple process, and the prepared dual-effect drug and fertilizer functional material can achieve the effect of long-term slow release of drug and fertilizer, providing a new solution for the development of green precision agriculture.

[0020] (3) The application of the dual-effect fertilizer and pesticide material provided by the present invention in promoting crop growth can promote rice growth and kill and remove barnyard grass.

[0021] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the figures. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0023] Figure 1 The infrared spectra of TS and TS-QNC prepared in Example 1 are shown.

[0024] Figure 2 Infrared spectra of PU and TS-QNC-PU prepared in Example 1, and TS-PU prepared in Comparative Example 1.

[0025] exist Figures 1-2 In the diagram: the vertical axis “Transmittance” represents light transmittance; the horizontal axis “Wavenumber” represents wavenumber.

[0026] Figure 3 C1s spectra of XPS characterization of TS and TS-QNC prepared in Example 1.

[0027] Figure 4 The O1s spectra of XPS characterization of TS and TS-QNC prepared in Example 1 are shown.

[0028] Figure 5 N1s spectra of the PU and TS-QNC-PU prepared in Example 1 and the TS-PU prepared in Comparative Example 1, characterized by XPS.

[0029] Figure 6 O1s spectra of XPS characterization of PU and TS-QNC-PU prepared in Example 1 and TS-PU prepared in Comparative Example 1.

[0030] exist Figures 3-6 In the diagram: the vertical axis “Intensity” represents intensity (dimensionless); the horizontal axis “Binding Energy” represents binding energy (unit: electron volt, eV).

[0031] Figure 7 The effects of different amounts of TS on the removal rate and adsorption capacity of QNC in Example 1 and Comparative Examples 3-5 are shown.

[0032] Figure 8 This study examines the effects of different concentrations of QNC on the removal rate and adsorption capacity under the same TS dosage conditions in Examples 1 and Comparative Examples 6-7.

[0033] exist Figure 7 and Figure 8 In the middle: the left vertical axis "QNC removal efficiency" represents the QNC removal rate; the right vertical axis "Absorption capacity" represents the adsorption capacity; Figure 7 The horizontal axis "Carbon content" in the graph represents the amount of TS used; Figure 8 The horizontal axis in the graph represents the concentration of QNC.

[0034] Figure 9 The effect of different dosages of TS-QNC in Example 1 and Comparative Examples 8-11 on the initial nitrogen release rate of the dual-effect fertilizer-pesticide material.

[0035] Figure 10The effect of different dual-effect fertilizer and pesticide materials prepared for Example 1 and Comparative Examples 1-2 on the initial nitrogen release rate.

[0036] exist Figures 9-10 In the middle: the vertical axis "Nitrogen initial release rate" represents the initial nitrogen release rate; in... Figure 9 The horizontal axis “TS-QNC content” in the figure represents the amount of TS-QNC used.

[0037] Figure 11 The effect of different dual-effect fertilizer and pesticide materials prepared for Example 1 and Comparative Examples 1-2 on nitrogen cumulative release rate.

[0038] exist Figure 11 In the middle: the vertical axis “N Cumulative release rate” represents the cumulative nitrogen release rate; the horizontal axis “Incubation time” represents the immersion time (in days) (i.e., the immersion time of the coated fertilizer in water).

[0039] Figure 12 The effect of different drug-fertilizer dual-effect functional materials prepared for Example 1, Comparative Example 1 and Comparative Example 12 on the cumulative release rate of QNC.

[0040] exist Figure 12 In the middle: the vertical axis “QNC Cumulative release rate” represents the cumulative release rate of QNC; the horizontal axis “time” represents the extraction time (in days).

[0041] Figure 13 SEM image of the PU-coated fertilizer prepared for Comparative Example 2.

[0042] Figure 14 SEM image of the TS-PU coated fertilizer prepared in Comparative Example 1.

[0043] Figure 15 SEM image of the TS-QNC-PU coated fertilizer prepared in Example 1.

[0044] Figure 16 The contact angle (WCA) test diagram of the PU-coated fertilizer prepared for Comparative Example 2.

[0045] Figure 17 The contact angle (WCA) test diagram of the TS-PU coated fertilizer prepared for Comparative Example 1.

[0046] Figure 18 The image shows the contact angle (WCA) test result of the TS-QNC-PU coated fertilizer prepared in Example 1.

[0047] Figure 19The results of soil bagging tests were conducted on the coated fertilizers prepared in Example 1 and Comparative Examples 1-2.

[0048] Figure 20 The effects of different treatment groups on the growth of rice and barnyard grass.

[0049] Figure 21 This is a schematic diagram illustrating the principle behind the coated fertilizer prepared in Example 1 promoting rice growth and causing damage to barnyard grass.

[0050] exist Figure 20 and Figure 21 In Chinese: "rice" refers to rice; "barnyard grass" refers to barnyard grass.

[0051] Figure 22 (a) is a SEM image of the PU-coated fertilizer at 100 μm after 7 days of extraction.

[0052] Figure 22 (b) is a SEM image of the PU-coated fertilizer at 10 μm after 7 days of extraction.

[0053] Figure 22 (c) is a SEM image of TS-PU coated fertilizer at 100 μm after 7 days of extraction.

[0054] Figure 22 (d) is a SEM image of TS-PU coated fertilizer at 10 μm after 7 days of extraction.

[0055] Figure 22 (e) is a SEM image of the TS-QNC-PU coated fertilizer at 100 μm after 7 days of extraction.

[0056] Figure 22 (f) is a SEM image of TS-QNC-PU coated fertilizer at 10 μm after 7 days of extraction.

[0057] Figure 23 (a) is a SEM image of the PU-coated fertilizer at 100 μm after 28 days of extraction.

[0058] Figure 23 (b) is a SEM image of the PU-coated fertilizer at 10 μm after 28 days of extraction.

[0059] Figure 23 (c) is a SEM image of TS-PU coated fertilizer at 100 μm after 28 days of extraction.

[0060] Figure 23 (d) is a SEM image of TS-PU coated fertilizer at 10 μm after 28 days of extraction.

[0061] Figure 23 (e) is a SEM image of TS-QNC-PU coated fertilizer at 100 μm after 28 days of extraction.

[0062] Figure 23 (f) is a SEM image of TS-QNC-PU coated fertilizer at 10 μm after 28 days of extraction.

[0063] Figure 24 (a) is a SEM image of TS-PU coated fertilizer at 500 μm after 56 days of extraction (in the figure, "Inner capsule" refers to the inner shell, i.e., the polyurethane membrane shell).

[0064] Figure 24 (b) is a SEM image of TS-PU coated fertilizer at 100 μm after 56 days of extraction.

[0065] Figure 24 (c) is a SEM image of TS-QNC-PU coated fertilizer at 500 μm after 56 days of extraction.

[0066] Figure 24 (d) is a SEM image of TS-QNC-PU coated fertilizer at 100 μm after 56 days of extraction. Detailed Implementation

[0067] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0068] Example 1: A dual-effect fertilizer and pesticide material includes a fertilizer core and a shell layer; the fertilizer core is fertilizer; the shell layer is wrapped around the outside of the fertilizer core; the shell layer includes a polyurethane layer (named PU) and a tobacco stem biochar layer loaded with herbicide (named TS-QNC) arranged sequentially from the inside to the outside, and the shell layer is named TS-QNC-PU; the herbicide is quinclorac acid (named QNC).

[0069] The fertilizer is urea.

[0070] The dual-effect fertilizer and pesticide material further includes a first sealing layer and a second sealing layer; the first sealing layer is disposed between the polyurethane layer and the tobacco stem biochar layer loaded with herbicide; the second sealing layer is disposed on the outside of the tobacco stem biochar layer loaded with herbicide; the first sealing layer is a microcrystalline wax layer; the second sealing layer is a microcrystalline wax layer.

[0071] The preparation method of the dual-effect drug-fertilizer material includes: Step S1: Prepare the polyurethane layer by spin coating on the outer side of the fertilizer core; After mixing the required amount of raw material components for the polyurethane layer, the mixture is first spin-coated onto the outer side of the fertilizer core to prepare a polyurethane prefabricated layer; after the polyurethane prefabricated layer undergoes a first curing treatment, the polyurethane layer is obtained, named PU. Step S2: Spin-coating the outer side of the polyurethane layer to prepare the tobacco stem biochar layer loaded with herbicide, thereby obtaining the dual-effect pesticide-fertilizer material; After mixing the required amount of herbicide-loaded tobacco stem biochar for the herbicide-loaded layer, the mixture is then spin-coated onto the outer side of the polyurethane layer to prepare a herbicide-loaded tobacco stem biochar pre-layer. The herbicide-loaded tobacco stem biochar pre-layer is then subjected to a second curing treatment to obtain the herbicide-loaded tobacco stem biochar layer, named TS-QNC.

[0072] The dual-effect fertilizer material prepared by the aforementioned method is named Coated Fertilizer TS-QNC-PU.

[0073] In step S2, the method for obtaining the tobacco stem biochar includes: First, the dried tobacco stems are crushed and sieved through a 40-mesh screen to obtain sieved tobacco stem powder. Second, the tobacco stem powder, ferric citrate, and phosphoric acid are mixed in a mass ratio of 30:2.204:101.1 and then heat-treated to obtain tobacco stem pre-charcoal. Then, the tobacco stem pre-charcoal is naturally cooled and washed with water until the filtrate is clear. Subsequently, the filter residue is collected and dried a second time to obtain dried tobacco stem pre-charcoal. Finally, the dried tobacco stem pre-charcoal is sieved through a 100-mesh screen to obtain sieved tobacco stem biochar, named TS. The first drying process uses a drying temperature of 60℃ and a drying time of 24 hours. The heat treatment is performed in an air atmosphere, with a heating temperature of 280°C and a heating time of 5 hours; the heating rate used in the heat treatment is 5°C / min.

[0074] In step S2, the method for obtaining the herbicide-loaded tobacco stem biochar includes: The tobacco stem biochar was added to a herbicide aqueous solution, mixed well, and then subjected to adsorption treatment to obtain the herbicide-loaded tobacco stem biochar. The concentration of the herbicide in the aqueous solution is 40 mg / L; The mass ratio of the tobacco stem biochar to the volume ratio of the herbicide aqueous solution is 0.1 g: 100 mL; The adsorption treatment was carried out under shaking conditions, with a shaking speed of 150 rpm, an adsorption temperature of 25℃, and an adsorption time of 90 min. The mass (specifically 1.0 g) of the tobacco stem biochar loaded with the herbicide used in the second spin coating is 1 / 200 of the mass of the fertilizer core; The second spin coating uses a spin coating temperature of 80±5 (specifically 80.0)℃, a spin coating time of 10min, and a spin coating speed of 50rpm.

[0075] In step S1, the raw material components required for the polyurethane layer are castor oil and polymethylene polyphenyl polyisocyanate in a mass ratio of 1.2:1. The preparation steps of the polyurethane preform layer include: The required amounts of castor oil and polymethylene polyphenyl polyisocyanate are placed separately and degassed under vacuum. The castor oil and polymethylene polyphenyl polyisocyanate are then alternately applied to the outside of the fertilizer core three times to prepare the polyurethane preform layer. The total mass of the castor oil and the polymethylene polyphenyl polyisocyanate used in the first spin coating is 3 / 40 of the mass of the fertilizer core; The first spin coating uses a spin coating temperature of 80±5 (specifically 80.0)℃, a spin coating time of 10 min, and a spin coating speed of 50 rpm; The vacuum degassing process uses a vacuum degassing temperature of 80℃ and a vacuum degassing time of 5 minutes.

[0076] The first curing process uses a curing temperature of 80.1℃ and a curing time of 8~10 (specifically 10) min; The second curing process uses a curing temperature of 80.0℃ and a curing time of 8~10 (specifically 10) min.

[0077] Between steps S1 and S2, the process further includes applying microcrystalline wax to the outer side of the polyurethane layer via a third spin coating to prepare a first sealing pre-layer; and then subjecting the first sealing pre-layer to a third curing treatment to obtain the first sealing layer. The spin coating process used in the third spin coating is a spin coating temperature of 80±5 (specifically 80.1)℃, a spin coating time of 10 min, and a spin coating speed of 50 rpm. The third curing process uses a curing temperature of 80.0℃ and a curing time of 10 minutes. The mass of the microcrystalline wax used in the third spin coating is 1 / 100 of the mass of the fertilizer core; After step S2, the process further includes spin-coating microcrystalline wax onto the outer side of the polyurethane layer to prepare a second sealing pre-layer; and then subjecting the second sealing pre-layer to a fourth curing treatment to obtain the second sealing layer. The spin coating process used in the fourth spin coating is a spin coating temperature of 80±5℃, a spin coating time of 10min, and a spin coating speed of 50rpm. The fourth curing process uses a curing temperature of 80.0℃ and a curing time of 10 minutes. The mass of the microcrystalline wax used in the fourth spin coating is 1 / 100 of the mass of the fertilizer core.

[0078] Comparative Example 1: Unlike Example 1, the herbicide-loaded tobacco stem biochar layer was replaced with a tobacco stem biochar layer, thus eliminating the use of herbicide. The product obtained from Comparative Example 1 is a herbicide-free slow-release fertilizer material, and its shell layer is named TS-PU. This herbicide-free slow-release fertilizer material is named coated fertilizer TS-PU.

[0079] Comparative Example 2: Unlike Example 1, the herbicide-loaded tobacco biochar layer was omitted; instead, only a polyurethane layer was wrapped around the outside of the fertilizer core. The product obtained from Comparative Example 2 was a conventional polyurethane-coated slow-release fertilizer material, the shell of which was named PU. This conventional polyurethane-coated slow-release fertilizer material was named coated fertilizer PU.

[0080] Comparative Example 3: Unlike Example 1, the mass ratio of the tobacco stem biochar to the volume ratio of the herbicide aqueous solution used was 0.05 g: 100 mL.

[0081] Comparative Example 4: Unlike Example 1, the mass ratio of the tobacco stem biochar to the volume ratio of the herbicide aqueous solution used was 0.15 g: 100 mL.

[0082] Comparative Example 5: Unlike Example 1, the mass ratio of the tobacco stem biochar to the volume ratio of the herbicide aqueous solution used was 0.20 g: 100 mL.

[0083] Comparative Example 6: Unlike Example 1, the concentration of the herbicide in the herbicide aqueous solution is 30 mg / L.

[0084] Comparative Example 7: Unlike Example 1, the concentration of the herbicide in the herbicide aqueous solution is 50 mg / L.

[0085] Comparative Example 8: Unlike Example 1, the mass of the tobacco stem biochar loaded with the herbicide used in the second spin coating was 0.25 g.

[0086] Comparative Example 9: Unlike Example 1, the mass of the tobacco stem biochar loaded with the herbicide used in the second spin coating was 0.5 g.

[0087] Comparative Example 10: Unlike Example 1, the mass of the tobacco stem biochar loaded with the herbicide used in the second spin coating was 0.75 g.

[0088] Comparative Example 11: Unlike Example 1, the mass of the tobacco stem biochar loaded with the herbicide used in the second spin coating was 1.25 g.

[0089] Comparative Example 12: Unlike Example 1, the polyurethane layer was omitted; instead, only a layer of tobacco stem biochar loaded with herbicide was wrapped around the outside of the fertilizer core. The product obtained from Comparative Example 12 was a slow-release fertilizer material wrapped with a layer of tobacco stem biochar loaded with herbicide, and its shell was named TS-QNC. This slow-release fertilizer material wrapped with a layer of tobacco stem biochar loaded with herbicide was named coated fertilizer TS-QNC.

[0090] The TS (i.e., tobacco stem biochar), TS-QNC (i.e., tobacco stem biochar layer loaded with the herbicide dichloroquinoline), PU (i.e., polyurethane layer), and TS-QNC-PU (i.e., a combination layer of tobacco stem biochar layer and polyurethane layer loaded with the herbicide dichloroquinoline) prepared in Example 1, as well as the TS-PU (i.e., a combination layer of tobacco stem biochar layer and polyurethane layer) prepared in Comparative Example 1, were analyzed by Fourier transform infrared spectroscopy (FTIR, vertex 80 / 80 v, Bruker, Germany) to explore the effect of different modifications on the surface groups of polyurethane.

[0091] See Figure 1 The characteristic peaks (-OH, -C=O) of TS and TS-QNC are at 3445 cm⁻¹. -1 1735cm -1 The adsorption of QNC near the site and the decrease in the intensity of the -OH peak of TS-QNC after adsorption suggest that the adsorption mechanism is mainly due to QNC occupying the active site -OH, leading to a decrease in the content of oxygen-containing groups such as hydroxyl groups, indicating that hydrogen bonds are formed between dichloroquinolinic acid and tobacco biochar.

[0092] See Figure 2 In the spectrum of PU, –NH and -C=O (approximately 3315 cm⁻¹) -1 1735 cm -1The characteristic peaks of TS-PU and TS-QNC-PU are clearly visible. The characteristic peaks (NH and -OH) of TS-PU and TS-QNC-PU show enhanced peak intensity after modification, indicating that TS and TS-QNC are successfully loaded onto the polyurethane surface. In addition, the -OH content of TS-QNC-PU is lower than that of TS-PU. This is because TS adsorbs QNC and consumes some -OH to form hydrogen bonds. Considering that the reduction of oxygen-containing groups such as hydroxyl groups will reduce the hydrophilicity of the shell to some extent, it shows that the preparation of TS-QNC-PU can simply and effectively improve the swelling resistance and water erosion resistance of polyurethane surface.

[0093] The TS (tobacco stem biochar), TS-QNC (tobacco stem biochar layer loaded with the herbicide dichloroquinoline), PU (polyurethane layer), and TS-QNC-PU (combination layer of tobacco stem biochar layer and polyurethane layer loaded with the herbicide dichloroquinoline) prepared in Example 1, as well as the TS-PU (combination layer of tobacco stem biochar layer and polyurethane layer) prepared in Comparative Example 1, were respectively used... To examine the participation of the oxygen-containing functional groups of TS prepared in Example 1 in the adsorption of QNC, X-ray photoelectron spectroscopy (XPS, K-Alpha, Thermo Fisher Scientific, America) was performed on TS and TS-QNC before and after QNC adsorption to analyze the changes in the functional groups on the material surface.

[0094] from Figure 1 and Figure 2 Infrared results indicate that both TS and TS-QNC contain both C and O elements. (See also...) Figure 3 After QNC adsorption on TS, the C=O content in the C1s spectrum decreased from 35.3% to 29.1%. This is attributed to the direct participation of the C=O functional group in the QNC adsorption process, possibly through hydrogen bonding interactions with the QNC molecule. Simultaneously, changes in the adsorption layer or electronic environment led to a relative decrease in signal intensity. See also Figure 4 The concentration of –OH in the O1s spectrum decreased from 42.9% to 41.9%. This is because the hydroxyl group acts as a hydrogen bond donor site, forming hydrogen bonds with the electronegative atoms in the QNC molecule. After adsorption, the number of free hydroxyl groups on the surface decreases, and some hydroxyl groups are covered by the adsorption layer. After adsorption, the carboxylic acid group concentration of TS-QNC decreased significantly, and the peak position of the carboxyl group shifted. This is because the carboxyl group (–COOH) is firmly bound to QNC through hydrogen bonding, resulting in a decrease in the density of free carboxyl groups on the surface. At the same time, the electron cloud density changes after the carboxyl group binds to the QNC molecule, leading to a shift in its binding energy. This further confirms the direct participation of oxygen-containing functional groups in the adsorption process.

[0095] To further elucidate the mechanism of action of TS and TS-QNC on polyurethane (PU) modification, the present invention also characterized PU, TS-PU and TS-QNC-PU by X-ray photoelectron spectroscopy (XPS).

[0096] See Figure 5 Compared to the original PU, the content of NH-C(=O)-O (carbamate bond) in the N1s spectrum of TS-PU and TS-QNC-PU is significantly increased. This is mainly attributed to the condensation reaction between the hydroxyl groups (-OH) on the surface of TS and the unreacted isocyanate groups (-NCO) in the PU matrix, forming new carbamate bonds, thereby chemically bonding TS to the PU molecular chain.

[0097] See Figure 6 The original PU contained 34.3% C=O (531.2 eV), which increased to 39.8% in the modified TS-PU and significantly to 55.1% in the TS-QNC-PU. This phenomenon is due, on the one hand, to the reaction of the hydroxyl groups in TS with the isocyanate groups in PU to form urethane bonds, increasing the proportion of C=O species in the system; on the other hand, compared with TS-PU, the C=O content in TS-QNC-PU was further increased by 15.3%, which is attributed to the fact that the QNC molecule itself is rich in carboxyl (-COOH) functional groups. During the process of loading TS-QNC onto the PU surface, these carboxyl groups were introduced, thus contributing additional C=O signals in the O1s spectrum.

[0098] See Figure 7 and Figure 8 As shown in Examples 1 and Comparative Examples 3-7, the adsorption performance exhibits a regular change when the TS dosage is adjusted within the range of 0.05-0.20 g and the QNC concentration is adjusted within the range of 30-50 mg / L. Under the conditions of 0.1 g TS and 40 mg / L QNC concentration (i.e., the conditions of Example 1), the TS removal rate (adsorption rate) for QNC reaches 94%, and the TS adsorption capacity is 38 mg / g. Although the adsorption capacity is highest at a TS dosage of 0.05 g, its removal rate is less than 75%, and excessively low dosages increase the difficulty and cost of subsequent TS and QNC separation and recovery processes. When the QNC concentration increases from 40 mg / L to 50 mg / L, the increase in TS adsorption capacity is limited. Considering adsorption efficiency, process feasibility, and economy, the optimal adsorption conditions are determined to be: TS dosage 0.1 g and QNC concentration 40 mg / L.

[0099] The nitrogen release performance of the coated fertilizers prepared in Examples 1, 1-2, and 8-12 was tested according to the national standard test method HG / T4216-2011. Specifically, 10g of each coated fertilizer was placed in a nylon mesh bag (100 mesh, 10cm wide, 15cm long), sealed, and then placed in an Erlenmeyer flask containing 200mL of water. The flask was then placed in a constant temperature incubator at 25℃ for static release. The nitrogen release rate of the fertilizer at 1, 3, 5, 7, 10, 14, 28, 42, 56, and 63 days, or the nitrogen release rate when the cumulative nitrogen release rate reached 80% or more, was measured. The concentration of urea nitrogen was detected using a UV-2450 Shimadzu Corporation (Japan). The sample solution was diluted to within the detection limit of the UV-2450 spectrophotometer before testing, as needed. First, prepare the p-dimethylaminobenzaldehyde colorimetric reagent, and allow it to react with urea in the sample solution for 20 minutes. Then, place the standard sample in a quartz cuvette and measure its absorbance at a wavelength of 430 nm. Finally, convert the measured absorbance to obtain the sample concentration.

[0100] See Figure 9 As shown in Examples 1 and Comparative Examples 8-11, when the dosage of TS-QNC increased from 0.25g to 1.0g, the initial nitrogen release rate of the dual-effect fertilizer-pesticide material gradually decreased (i.e., 1 day after release), and the controlled-release effect was enhanced. However, when the dosage was further increased to 1.25g, the initial nitrogen release rate actually increased, and the controlled-release performance decreased. This indicates that when the dosage of TS-QNC is 1.0g, the controlled-release effect of the dual-effect fertilizer-pesticide material is optimal, meeting the requirements of the national controlled-release fertilizer standard (GB / T 23348-2009).

[0101] See Figures 10-11 As shown in Examples 1 and Comparative Examples 1 and 2, the initial (i.e., 1-day release) nitrogen release rates of PU, TS-PU, and TS-QNC-PU were 2.69%, 19.44%, and 7.39%, respectively; the cumulative nitrogen release rates over 28 days were 22.22%, 69.94%, and 26.37%, respectively. According to the national standard (GB / T 23348-2009), the initial release rate of slow-release fertilizers should be less than 12%, and the cumulative release rate over 28 days should not exceed 75%. The initial release rate of TS-PU (19.44%) significantly exceeded the standard limit and did not meet the requirements for slow-release fertilizers; while the initial release rate (7.39%) and the cumulative release rate over 28 days (26.37%) of TS-QNC-PU both met the national standard requirements. It is noteworthy that during long-term release, the cumulative nitrogen release period of TS-QNC-PU reached 140 days, demonstrating excellent controlled-release performance.

[0102] See Figure 12As shown in Examples 1 and 12, TS-QNC without PU loading (i.e., Comparative Example 12) completes the release of QNC within 5 days; while in TS-QNC-PU (i.e., Example 1), the release rate of QNC is significantly reduced, and the release period is extended to more than 70 days. This indicates that loading TS-QNC, which serves as the outer shell, onto the PU matrix, which serves as the inner shell, as in Example 1 can not only effectively delay nitrogen release but also endow the dual-function fertilizer-pesticide material with good controlled-release capabilities, achieving synergistic controlled-release of fertilizer and pesticide.

[0103] To investigate the anti-swelling performance of the shell structure of the dual-effect fertilizer material in practical applications, this invention sampled the coated fertilizers prepared in Example 1 (TS-QNC-PU), Comparative Example 1 (TS-PU), and Comparative Example 2 (PU) for scanning electron microscopy (SEM, Japan-JEOL-JSM-IT700HR) before immersion. The static water extraction test conditions were as follows: Samples of the coated fertilizers prepared in Example 1 (TS-QNC-PU), Comparative Example 1 (TS-PU), and Comparative Example 2 (PU) were subjected to static water extraction tests. Specifically, 30g of each coated fertilizer sample was weighed and repeated three times. During each test, the coated fertilizer was immersed in distilled water at a temperature of 20-25°C (specifically 22°C). After 56 days, the samples were removed for verification of anti-swelling performance.

[0104] Before immersion: see Figure 13 As shown in Comparative Example 2, pure PU has a smooth surface, uniform cross-sectional structure, and no visible pores; in comparison, see [reference needed]. Figure 14 As shown in Comparative Example 1, a large number of protrusions appear on the surface of TS-PU (see...). Figure 14 (The protrusions within the yellow dashed circle) This is because the abundant hydroxyl and carboxyl functional groups on the surface of tobacco stem biochar can undergo condensation reactions with isocyanates on the polyurethane molecular chains. However, tobacco stem biochar particles are prone to local aggregation during film formation, leading to physical protrusions on the polyurethane film surface, which in turn reduces the film density and affects the sustained-release performance; see also Figure 15 As seen in Example 1, the TS-QNC-PU surface also has protrusions (see Example 1). Figure 15 (The raised areas within the yellow dashed circle) are more uniformly distributed than those in TS-PU; the quinoline ring and carboxylic acid groups in the QNC molecule can form hydrogen bonds with the urethane groups in PU. This intermolecular force enhances the load stability of biochar in the membrane layer and further improves the compactness of the polyurethane membrane layer.

[0105] After 7 days of extraction: See Figure 22 (a) Figure 22 (b) Figure 22 (e) and Figure 22(f) No pores or cracks were observed on the surface and cross-section of PU and TS-QNC-PU, while see [reference needed]. Figure 22 (c) and Figure 22 (d) Separation of the membrane layer from the fertilizer core and small pores appear in the TS-PU cross section (e.g. Figure 22 (d) The hole within the red dashed circle.

[0106] After 28 days of extraction: See Figure 23 (c) and Figure 23 (d) Cracks appear on the TS-PU surface (e.g.) Figure 23 (d) The cracks pointed to by the yellow arrows) and the holes (such as Figure 23 (c) the hole within the yellow dashed circle); see also Figure 23 (a) and Figure 23 (b) Although the PU film did not have obvious pores, compared with the film extracted for 7 days, the surface of the film showed signs of erosion of the polyurethane network structure (see the protrusions within the yellow dashed circle in 23(b)); in contrast, see Figure 23 (e) and Figure 23 (f) TS-QNC-PU still maintains a smooth surface and a dense structure.

[0107] The above results demonstrate that TS-QNC-PU exhibits excellent anti-swelling properties. Furthermore, cross-sectional SEM analysis was performed on TS-PU and TS-QNC-PU after 56 days of extraction to compare their structural stability. The results are shown in [see attached image]. Figure 24 (a) and Figure 24 (b) The urea inside the TS-PU has completely dissolved, leaving only the polyurethane membrane shell; while see [reference needed] Figure 24 (c) and Figure 24 (d) A large amount of solid urea still exists inside TS-QNC-PU, indicating that the modified shell membrane can effectively hinder the diffusion and permeation of water molecules and significantly improve the slow-release performance.

[0108] Water contact angle (WCA) testing further verified the aforementioned changes in anti-swelling properties. The water contact angle (WCA) of the coated fertilizers prepared in Example 1 (TS-QNC-PU), Comparative Example 1 (TS-PU), and Comparative Example 2 (PU) before immersion was measured using a contact angle meter (YIKE-360A, Chengde YIKE Testing Instrument Factory) at room temperature. Figures 16-18As shown, pure PU has a water contact angle of 112°, exhibiting hydrophobicity. TS-PU, due to the presence of numerous polar groups such as hydroxyl and amino groups on its surface, readily forms hydrogen bonds with water molecules, resulting in a contact angle of 81°, exhibiting hydrophilic properties. In contrast, TS-QNC-PU, with QNC adsorbed on TS and occupying the active sites on the TS surface, significantly reduces the content of oxygen-containing functional groups, causing the contact angle to rise to 114°, demonstrating even better hydrophobicity than pure PU. XPS analysis reveals that after TS adsorbs QNC, on the one hand, QNC reacts with the oxygen-containing groups on the TS surface to participate in the reaction of isocyanates in the polyurethane, forming urethane bonds and improving the membrane's density; on the other hand, the introduction of QNC consumes some of the hydrophilic functional groups on TS, reducing the surface hydrophilicity of the membrane, thereby synergistically inhibiting water from entering the membrane shell and enhancing the sustained-release performance.

[0109] The coated fertilizers prepared in Example 1 (TS-QNC-PU), Comparative Example 1 (TS-PU), and Comparative Example 2 (PU) were sampled and subjected to soil burial experiments. Specifically, 10g of each coated fertilizer sample was weighed and placed into a 200-mesh nylon mesh bag. Five replicates were set up for each treatment. The samples were buried in the soil (yellow-brown soil type) at a depth of 10-15cm according to a randomized block design, maintaining a field water holding capacity of 60%-70% and an ambient temperature fluctuating between 0-15℃. After 68 days, the samples were dug up to verify their anti-swelling performance.

[0110] After the soil bag burial test, no visible membrane rupture was observed in any of the three groups of coated fertilizers: Example 1 (TS-QNC-PU), Comparative Example 1 (TS-PU), and Comparative Example 2 (PU). Specifically, the fertilizer cores of PU and TS-PU were partially dissolved, indicating that water had fully penetrated into the membrane; while the fertilizer core of TS-QNC-PU remained mostly solid, with only a small amount dissolved. This trend is consistent with the appearance results of the coated fertilizers in the static water extraction test, confirming that TS-QNC-PU also exhibits excellent controlled-release performance in actual soil environments.

[0111] To evaluate the comprehensive performance (nitrogen control + weed control) of TS-QNC-PU in a real-world environment, disease-free rice and barnyard grass seeds with uniform plumpness were selected. These seeds were then disinfected with a 5% sodium hypochlorite solution for 20 minutes, followed by rinsing with distilled water to remove the sodium hypochlorite. The seeds were then soaked in deionized water and placed in a 25°C incubator for 12 hours. After soaking, the seeds were transferred to a 37°C incubator for germination for 12 hours. Germinated seeds were then placed in 500 mL of rice nutrient solution (prepared according to IRRI standards) and cultured in a 25°C incubator. Incubator conditions were set at 25°C, 14 hours of daylight, 10 hours of night, and 75% relative humidity. The nutrient solution was changed every 4 days, and seedling emergence was observed. In the hydroponic experiment, rice plants (or barnyard grass) were placed in petri dishes containing 400 mL of water. 5 g each of urea, the coated fertilizer prepared in Example 1 (TS-QNC-PU), Comparative Example 1 (TS-PU), and Comparative Example 2 (PU) were added for single-factor experiments. A blank control group (CK group) without fertilizer was also included. The hydroponic experiment lasted for 5 days. The results are as follows: Figure 20 As shown, barnyard grass treated with urea showed severe yellowing, which was due to high-concentration ammonia stress (seedling burn) caused by the rapid release of pure urea. Compared with the control group, barnyard grass treated with PU and TS-PU showed slight yellowing, while barnyard grass treated with TS-QNC-PU was almost completely dead. During the hydroponic period (5 days), the nitrogen release rate was TS-PU > TS-QNC-PU. The degree of barnyard grass mortality in the TS-QNC-PU treatment was significantly greater than that in the TS-PU treatment, indicating that it was mainly caused by the release of dichloroquinoline acid from TS-QNC-PU, rather than nitrogen stress. This shows that TS-QNC-PU has good herbicide slow-release activity. For the rice group, the growth of rice under the TS-QNC-PU treatment was not significantly different from that under the control group, proving that this fertilizer-pesticide carrier has biosafety for crops.

[0112] The above results demonstrate that modifying polyurethane with TS-QNC not only optimizes the controlled-release performance of nitrogen but also endows the coating material with the function of the slow-release herbicide QNC. Its controlled-release mechanism can be summarized as follows: See [link to relevant documentation] Figure 21(1) Nitrogen controlled release: On the one hand, QNC improves the hydrophobicity of the polyurethane membrane by loading TS-QNC onto the polyurethane membrane through the oxygen-containing functional groups (hydroxyl, carboxyl, etc.) on the surface of TS, thereby inhibiting the diffusion of water into the membrane; on the other hand, the quinoline ring and carboxylic acid group in the QNC molecule easily form hydrogen bonds with the urethane group of polyurethane, so that TS-QNC is uniformly loaded and the membrane density is increased. The synergistic effect of the two significantly delays the release of urea. (2) Herbicide slow release: First, QNC is adsorbed onto TS through pore filling and van der Waals forces, and the desorption rate is slow; second, the intermolecular forces such as hydrogen bonds between QNC and polyurethane further hinder the rapid release of QNC; the combined effect of the two achieves the continuous slow release of QNC, thereby effectively inhibiting the growth of barnyard grass, while not causing phytotoxicity to rice.

[0113] The above description is only a preferred embodiment of the present invention and does not limit the scope of the present invention. All equivalent structural transformations made under the inventive concept of the present invention using the contents of the present invention specification and drawings, or direct / indirect applications in other related technical fields, are included within the protection scope of the present invention.

Claims

1. A dual-function material for both medicinal and fertilizer effects, characterized in that, It includes a fertilizer core and a shell layer; the fertilizer core is fertilizer; the shell layer is wrapped around the outside of the fertilizer core; the shell layer includes a polyurethane layer and a tobacco stem biochar layer loaded with herbicide arranged sequentially from the inside to the outside; the herbicide includes quinclorac acid.

2. The dual-effect fertilizer-pesticide material as described in claim 1, characterized in that, The fertilizer includes urea.

3. The dual-effect fertilizer-pesticide material as described in claim 2, characterized in that, It also includes a first sealing layer and a second sealing layer; the first sealing layer is disposed between the polyurethane layer and the herbicide-loaded tobacco biochar layer; the second sealing layer is disposed on the outside of the herbicide-loaded tobacco biochar layer; the first sealing layer includes a microcrystalline wax layer; the second sealing layer includes a microcrystalline wax layer.

4. A method for preparing a dual-effect drug-fertilizer material as described in claim 3, characterized in that, include: Step S1: Prepare the polyurethane layer by spin coating on the outer side of the fertilizer core; After the raw material components required for the polyurethane layer are mixed evenly, they are spin-coated onto the outer side of the fertilizer core to prepare a polyurethane prefabricated layer; after the polyurethane prefabricated layer is subjected to a first curing treatment, the polyurethane layer is obtained. Step S2: Spin-coating the outer side of the polyurethane layer to prepare the tobacco stem biochar layer loaded with herbicide, thereby obtaining the dual-effect pesticide-fertilizer material; After mixing the required amount of herbicide-loaded tobacco stem biochar for the herbicide-loaded layer, the mixture is then spin-coated onto the outer side of the polyurethane layer to prepare a pre-formed layer of herbicide-loaded tobacco stem biochar. The pre-formed layer of herbicide-loaded tobacco stem biochar is then subjected to a second curing treatment to obtain the herbicide-loaded tobacco stem biochar layer.

5. The preparation method of the dual-effect drug-fertilizer material as described in claim 4, characterized in that, In step S2, the method for obtaining the tobacco stem biochar includes: First, the dried tobacco stems are crushed and sieved through a 40-mesh screen to obtain sieved tobacco stem powder. Second, the tobacco stem powder, ferric citrate, and phosphoric acid solution are mixed in a mass ratio of 30:2.1~2.4:96~108 and then heat-treated to obtain pre-charred tobacco stems. Then, the pre-charred tobacco stems are naturally cooled and washed with water until the filtrate is clear. Subsequently, the filter residue is collected and dried a second time to obtain dried pre-charred tobacco stems. Finally, the dried pre-charred tobacco stems are sieved through a 100-mesh screen to obtain sieved tobacco stem biochar. The first drying process uses a drying temperature of 60±5℃ and a drying time of 24±2h. The heat treatment is performed in an air atmosphere, with a heating temperature of 280±5℃ and a heating time of 5±0.5h; the heating rate used in the heat treatment is 5±1℃ / min. The phosphoric acid solution comprises an aqueous solution of phosphoric acid with a mass concentration of 85%.

6. The preparation method of the dual-effect drug-fertilizer material as described in claim 4, characterized in that, In step S2, the method for obtaining the herbicide-loaded tobacco stem biochar includes: The tobacco stem biochar was added to a herbicide aqueous solution, mixed well, and then subjected to adsorption treatment to obtain the herbicide-loaded tobacco stem biochar. The concentration of the herbicide in the aqueous solution is 40 ± 1 mg / L; The mass ratio of the tobacco stem biochar to the volume ratio of the herbicide aqueous solution is 0.1 g: 800~1500 mL; The adsorption treatment was completed under shaking conditions, with a shaking speed of 150±5 rpm, an adsorption temperature of 25±2℃, and an adsorption time of 90±10 min. The mass of the herbicide-loaded tobacco stem biochar used in the second spin coating is 1:167~250 of the mass of the fertilizer core; The second spin coating uses a spin coating temperature of 80±5℃, a spin coating time of 10±3min, and a spin coating speed of 50±5rpm.

7. The preparation method of the dual-effect drug-fertilizer material as described in claim 4, characterized in that, In step S1, the raw material components required for the polyurethane layer include castor oil and polymethylene polyphenyl polyisocyanate in a mass ratio of 1.1 to 1.6:

1. The preparation steps of the polyurethane preform layer include: The required amounts of castor oil and polymethylene polyphenyl polyisocyanate are placed separately and degassed under vacuum. The castor oil and polymethylene polyphenyl polyisocyanate are then alternately spin-coated onto the outside of the fertilizer core 3 to 8 times to prepare the polyurethane preform layer. The total mass of the castor oil and the polymethylene polyphenyl polyisocyanate used in the first spin coating is 6% to 10% of the mass of the fertilizer core; The first spin coating uses a spin coating temperature of 80±5℃, a spin coating time of 10±3min, and a spin coating speed of 50rpm. The vacuum degassing process uses a vacuum degassing temperature of 80±5℃ and a vacuum degassing time of 4~9min.

8. The preparation method of the dual-effect drug-fertilizer material as described in claim 4, characterized in that, The curing temperature for the first curing treatment is 80±5℃, and the curing time is 7~15min; The second curing process uses a curing temperature of 80.0±5℃ and a curing time of 7~15min.

9. The preparation method of the dual-effect drug-fertilizer material as described in claim 8, characterized in that, Between steps S1 and S2, the process further includes applying microcrystalline wax to the outer side of the polyurethane layer via a third spin coating to prepare a first sealing pre-layer; and then subjecting the first sealing pre-layer to a third curing treatment to obtain the first sealing layer. The spin coating process used in the third spin coating is a spin coating temperature of 80±5℃, a spin coating time of 10±3min, and a spin coating speed of 50±5rpm. The curing temperature for the third curing process is 80.0±5℃, and the curing time is 7~15min. The mass of the microcrystalline wax used in the third spin coating is 0.9% to 1.2% of the mass of the fertilizer core. After step S2, the process further includes spin-coating microcrystalline wax onto the outer side of the polyurethane layer to prepare a second sealing pre-layer; and then subjecting the second sealing pre-layer to a fourth curing treatment to obtain the second sealing layer. The spin coating process for the fourth spin coating is characterized by a spin coating temperature of 80±5℃, a spin coating time of 10±3min, and a spin coating speed of 50±5rpm. The curing temperature for the fourth curing process is 80.0±5℃, and the curing time is 7~15min. The mass of the microcrystalline wax used in the fourth spin coating is 0.9% to 1.2% of the mass of the fertilizer core.

10. The application of the dual-effect fertilizer and pesticide material as described in claim 5 in promoting crop growth.

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