Photocatalytic nitrogen fertilizer preparation and application integrated device and use method thereof

Abstract

The invention discloses a photocatalytic nitrogen fertilizer preparation and application integrated device in the technical field, the photocatalytic nitrogen fertilizer preparation and application integrated device comprises a floating support, the floating support is arranged in a paddy field, the upper part of the floating support is fixedly provided with a nitrogen fertilizer preparation mechanism, and the nitrogen fertilizer preparation mechanism comprises a reaction tank; the device uses solar energy as the only energy to drive the air pump, and does not depend on fossil energy; in combination with reaction period control, the concentration of ammonium nitrogen in the field water can be stably maintained at a proper concentration; ammonium nitrogen is dissolved in water and directly enters crop rhizosphere to be absorbed; the lifting ring is pushed and extruded through the reset spring, the aeration nozzle is used for aeration, the gradient photocatalytic material can dissolve ammonium nitrogen generated by nitrogen in air in water under photoreaction, under the action of the reset spring, the lifting ring can achieve lifting adjustment, the position can be conveniently adjusted through air pressure, and the gradient photocatalytic material can be recycled. And the turbine blades can rotate by virtue of the aerated air flow, so that a solution in the reaction tank is stirred, and the sufficiency of ammonium nitrogen dissolved in water is conveniently improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of agricultural production and fertilizer preparation, more particularly to the field of photocatalytic nitrogen fixation and nutrient management equipment, and particularly relates to a photocatalytic nitrogen fertilizer preparation and application integrated device and a use method thereof. BACKGROUND

[0002] Nitrogen fertilizer is one of the most important nutrient inputs in agricultural production, and its yield and application efficiency directly affect crop yield and quality. At present, agricultural nitrogen fertilizer mainly relies on chemical industry to synthesize ammonia by Haber-Bosch process and then process into urea, ammonium nitrate, compound fertilizer and other products. The production process of this kind of nitrogen fertilizer consumes a large amount of fossil energy and emits greenhouse gases; when applied in the field, due to the easy volatilization, leaching and runoff of nitrogen, the nitrogen utilization rate of crops is generally low (about 30%-35%), and at the same time, environmental problems such as air pollution and water eutrophication are caused.

[0003] In order to improve the utilization rate of nitrogen fertilizer and reduce environmental risks, existing technologies attempt to use slow-release fertilizer, controlled-release fertilizer, organic fertilizer and the like, or optimize the application depth and time through fertilization machinery. These methods improve the matching of nitrogen release and crop demand to some extent, but still have the following shortcomings: the production cost of slow-release and controlled-release fertilizers is high, the manufacturing process is complex, and the field promotion is limited; the nitrogen content of organic fertilizer is low, and the release speed is slow, which is difficult to meet the nitrogen demand of crops in a short time; the fertilization machinery is mainly single conveying and burying function, and lacks the ability to prepare nitrogen fertilizer on site, and the nitrogen source still needs external supply; the existing field liquid fertilizer preparation device relies on chemical synthesis of nitrogen source, and fails to fully utilize the nitrogen in the air as raw material.

[0004] Photocatalytic nitrogen fixation technology uses light energy to reduce nitrogen (N2) in the air to ammonia (NH3) or ammonium nitrogen (NH4+) at normal temperature and pressure, which has the advantages of low energy consumption and environmental friendliness. However, current photocatalytic nitrogen fixation is mostly in the laboratory stage, and the common reactor structure is not suitable for outdoor or field environment, which has problems such as unstable light conditions, low three-phase contact efficiency of nitrogen-gas-water-catalyst, easy volatilization loss of generated ammonia, and lack of integrated device combining photocatalytic nitrogen production and field application.

[0005] Therefore, it is urgent to develop a device that can directly use sunlight and air to prepare soluble nitrogen fertilizer in the field and realize on-site application, so as to improve the utilization rate of nitrogen, reduce the dependence on chemical fertilizer and reduce environmental pollution. SUMMARY

[0006] In view of the deficiencies in the prior art, the present application provides a new technical solution of a photocatalytic nitrogen fertilizer preparation and application integrated device and a use method thereof.

[0007] The purpose of the application is achieved in that the application discloses a photocatalytic nitrogen fertilizer preparation and application integrated device.

[0008] Further, the inside of the reaction tank is internally attached with a positioning rod, the upper and lower ends of the positioning rod are fixedly installed with return springs respectively, and a lifting ring is fixedly connected between the two return springs and movably installed on the positioning rod.

[0009] Further, the outside of the lifting ring is welded with four positioning plates, a first aeration ring and a second aeration ring are fixedly installed on the four positioning plates, and aeration nozzles are connected to the bottoms of the first aeration ring and the second aeration ring at equal angles.

[0010] Further, shaft rods are fixedly installed on the four positioning plates, the shaft rods are arranged between the first aeration ring and the second aeration ring, and turbine blades are movably installed at the upper ends of the shaft rods.

[0011] Further, a shunt pipe is communicated between the first aeration ring and the second aeration ring, a communication pipeline is sealingly communicated in the middle of the shunt pipe, the other end of the communication pipeline is sealingly connected with a gas delivery port of a micro air pump, and the micro air pump is electrically connected with the storage battery.

[0012] Further, four supporting plates are fixedly attached to the bottom of the reaction tank, fixed rings are fixedly connected to the upper ends of the four supporting plates, low-activity photocatalytic materials and high-activity photocatalytic materials are fixedly installed in the inside of the fixed rings, and the low-activity photocatalytic materials are arranged below the high-activity photocatalytic materials.

[0013] Further, a liquid outlet pipe is communicated to one side of the bottom of the reaction tank, a filter is installed and connected to the liquid outlet pipe, and an electromagnetic control valve is fixedly installed at the end of the liquid outlet pipe.

[0014] Further, the low-activity photocatalytic materials adopt graphite phase carbon nitride composite materials, the high-activity photocatalytic materials adopt graphite phase carbon nitride composite materials doped with nano metal, the low-activity photocatalytic materials and the high-activity photocatalytic materials enhance the nitrogen adsorption capacity and improve the photocatalytic reaction efficiency through the porous structure of MOF, the reaction tank adopts glass fiber reinforced polypropylene with a nano silicon dioxide coating sprayed on the inside, and a transparent light collecting cover is arranged above the reaction tank.

[0015] A method for using a photocatalytic nitrogen fertilizer preparation and application integrated device, comprising the following steps: S1, installation and connection of the device: the nitrogen fertilizer preparation mechanism is fixedly installed on the field ground or floats in the water body through a floating support, and each device is connected through a communication pipeline and a sealing joint; S2, gas supply and nitrogen fertilizer preparation: air is input into the nitrogen fertilizer preparation mechanism through a micro air pump and a communication pipeline; S3, photocatalytic reaction: when the air is input into the nitrogen fertilizer preparation mechanism, nitrogen fertilizer solution is prepared through gradient photocatalytic material for light reaction; S4, filtration and liquid outlet unit: nitrogen fertilizer solution is discharged through a liquid outlet pipe and a filter at the bottom of the nitrogen fertilizer preparation mechanism, and is directly used for field irrigation.

[0016] Further, the filter adopts a self-cleaning nanometer membrane, the surface of which is coated with a graphene coating, and periodic automatic cleaning is realized through an ultrasonic cleaning device; The self-cleaning nanometer membrane is provided with three levels: The first level is a microfiltration membrane, which is used for filtering large-particle photocatalytic materials; The second level is a nanofiltration membrane, which is used for separating ammonium nitrogen and small-particle impurities; The third level is a reverse osmosis membrane, which is used for further purifying the nitrogen fertilizer solution.

[0017] Compared with the prior art, the device of the present application has the following beneficial effects: the device uses solar energy as the only energy source to drive the air pump and does not rely on fossil energy; the photocatalytic reaction is carried out at normal temperature and pressure without the need for high temperature and pressure conditions, and the running process almost has zero carbon emission, which can save a large amount of energy compared with the industrial Haber-Bosch method for ammonia production; and the nitrogen in the air can be directly converted into soluble ammonium nitrogen in the field, and the ammonium nitrogen can be directly applied to the farmland after the reaction period, avoiding the problems of transportation, storage and secondary loss in the process from production to application of industrial nitrogen fertilizer; through the aeration system, the nitrogen-water-photocatalytic material three-phase is fully contacted, and combined with the reaction period control, the ammonium nitrogen concentration in the field water can be stably maintained at a suitable concentration, and the absorption rate of crops is significantly improved; The generated ammonium nitrogen is dissolved in water and directly absorbed into the crop rhizosphere, reducing ammonia volatilization, runoff and leaching; no additional chemical additives are introduced during the running process, no secondary pollution is generated, and the risk of water eutrophication can be effectively reduced; the photocatalytic material is separated from the nitrogen fertilizer solution through the filter and can be reused multiple times, reducing the running cost and reducing solid waste emission; the device structure is simple and corrosion-resistant, and can be fixedly installed or floated on the water surface, adapting to different farmland conditions; solar power supply combined with a storage battery can realize continuous operation, and is suitable for long-term use in remote or non-electricity areas; The application realizes pushing the lifting ring through the reset spring, and the aeration nozzles at the lower part of the first aeration ring and the second aeration ring are used for aeration, which facilitates air input to the inside of the reaction tank, so that the gradient photocatalytic material can dissolve the ammonium nitrogen generated by nitrogen in the air in water under the light reaction, and in the process of aeration, the first aeration ring and the second aeration ring are reversely pushed under the action of the reverse blowing force of the air, and the lifting ring can realize lifting adjustment under the action of the reset spring, which facilitates the position adjustment through air pressure, and the turbine blade is arranged on the positioning plate, so that the airflow of aeration can impact the turbine blade, the turbine blade can rotate, the solution in the reaction tank is stirred, and the solubility of ammonium nitrogen in water is improved.

[0018] Other features of the present application, and their advantages, will become apparent in the non-limiting detailed description of exemplary embodiments of the present application, which is presented in connection with the following drawings. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only embodiments of the present application, and those skilled in the art can obtain other drawings according to the provided drawings without creative labor.

[0020] Figure 1 The step flowchart of the present application.

[0021] Figure 2 The system schematic diagram of the present application.

[0022] Figure 3 The nitrogen fertilizer preparation mechanism schematic diagram of the present application.

[0023] Figure 4 The reaction tank internal structure bottom view of the present application.

[0024] Figure 5 The reaction tank internal structure top view of the present application.

[0025] Figure 6 The reaction tank internal structure partial view of the present application.

[0026] The diagram shows the following components: 1. Floating support; 2. Nitrogen fertilizer preparation mechanism; 201. Reaction tank; 202. Positioning rod; 203. Return spring; 204. Lifting ring; 205. Positioning plate; 206. First aeration ring; 207. Second aeration ring; 208. Aeration nozzle; 209. Shaft; 210. Turbine blade; 211. Diverter pipe; 212. Support plate; 213. Fixing ring; 214. Low-activity photocatalytic material; 215. High-activity photocatalytic material; 216. Liquid outlet pipe; 217. Filter; 218. Electromagnetic control valve; 3. Miniature air pump; 4. Connecting pipe; 5. Solar photovoltaic panel; 6. Charge converter; 7. Battery. Detailed Implementation

[0027] 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 some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] like Figures 2-6 As shown, an integrated photocatalytic nitrogen fertilizer preparation and application device includes a floating support 1, which is set in a paddy field. A nitrogen fertilizer preparation mechanism 2 is fixedly installed on the upper part of the floating support 1. The nitrogen fertilizer preparation mechanism 2 includes a reaction tank 201, and is also equipped with a solar photovoltaic panel 5, a charging converter 6, and a storage battery 7. The solar photovoltaic panel 5 receives sunlight to generate electricity, and the storage battery 7 is used to store the electricity. It should be noted that the floating support 1 is designed to allow the nitrogen fertilizer preparation mechanism 2 to be installed in the paddy field without the need for additional excavation or modification of the farmland structure, thus avoiding damage to the physical structure of the soil. At the same time, the water body is used as a natural support medium, reducing installation costs. The reaction tank 201 is located on the upper part of the floating support 1 and can be fully exposed to natural light. Combined with the light-transmitting cover design of the light-transmitting material, the efficiency of photocatalytic reaction is significantly improved.

[0029] In this embodiment, preferably, a positioning rod 202 is bonded and installed in the middle of the interior of the reaction vessel 201. A return spring 203 is fixedly installed at the upper and lower ends of the positioning rod 202, and a lifting ring 204 is fixedly connected between the two return springs 203. The lifting ring 204 is movably installed on the positioning rod 202. It should be noted that the positioning rod 202 is fixedly adhered in the inside of the reaction tank 201, facilitating the fixation of the positioning rod 202, and the lifting ring 204 is supported by the reset spring 203, which can reset and adjust the lifting ring 204, and can adapt to the adjustment, facilitating the adaptive reaction treatment in water of different depths.

[0030] In the embodiment, preferably, four positioning plates 205 are welded outside the lifting ring 204, the first aeration ring 206 and the second aeration ring 207 are fixedly installed on the four positioning plates 205, and the bottom of the first aeration ring 206 and the second aeration ring 207 is connected with the aeration nozzles 208 at equal angles. It should be noted that the four positioning plates 205 are set to fixedly install the first aeration ring 206 and the second aeration ring 207, facilitating the stable lifting adjustment of the lifting ring 204, and the aeration nozzles 208 at equal angles are used to realize the aeration treatment of the solution in the inside of the reaction tank 201.

[0031] In the embodiment, preferably, the shaft rod 209 is fixedly installed on the four positioning plates 205, the shaft rod 209 is arranged between the first aeration ring 206 and the second aeration ring 207, and the upper end of the shaft rod 209 movably installs the turbine blade 210. It should be noted that the shaft rod 209 is installed on the positioning plate 205, the turbine blade 210 is movably installed by the shaft rod 209, and the shaft rod 209 is arranged between the first aeration ring 206 and the second aeration ring 207, facilitating the driving of the turbine blade 210 by the air bubbles when the air is blown out by the aeration nozzles 208, so that the turbine blade 210 can rotate quickly, and the solution in the reaction tank 201 can be mixed and stirred by the turbine blade 210.

[0032] In the embodiment, preferably, the first aeration ring 206 and the second aeration ring 207 are communicated with the shunt pipe 211, the middle of the shunt pipe 211 is sealingly communicated with the communication pipeline 4, the other end of the communication pipeline 4 is sealingly connected with the air conveying port of the micro air pump 3, the micro air pump 3 is electrically connected with the storage battery 7. It should be noted that the shunt pipe 211 is set to communicate the first aeration ring 206 and the second aeration ring 207, and the communication pipeline 4 is used to transport the airflow conveyed by the micro air pump 3 to the shunt pipe 211, and then to the inside of the first aeration ring 206 and the second aeration ring 207, so that the aeration nozzles 208 can be fully aerated in the reaction tank 201.

[0033] In the embodiment, preferably, the bottom of the reaction tank 201 is fixedly connected with four support plates 212, the upper ends of the four support plates 212 are fixedly connected with a fixed ring 213, the inside of the fixed ring 213 is fixedly installed with a low-activity photocatalytic material 214 and a high-activity photocatalytic material 215, and the low-activity photocatalytic material 214 is arranged below the high-activity photocatalytic material 215. It should be noted that the support plates 212 are used to fix and install the fixed ring 213, so as to keep the stability of the fixed ring 213 in the reaction tank 201, and the inside of the fixed ring 213 is installed with the low-activity photocatalytic material 214 and the high-activity photocatalytic material 215, so as to realize the segmented absorption and release of nitrogen and prolong the service life of the materials.

[0034] In the embodiment, preferably, the bottom of the reaction tank 201 is fixedly connected with four support plates 212, the upper ends of the four support plates 212 are fixedly connected with a fixed ring 213, the inside of the fixed ring 213 is fixedly installed with a low-activity photocatalytic material 214 and a high-activity photocatalytic material 215, and the low-activity photocatalytic material 214 is arranged below the high-activity photocatalytic material 215. It should be noted that the support plates 212 are used to fix and install the fixed ring 213, so as to keep the stability of the fixed ring 213 in the reaction tank 201, and the inside of the fixed ring 213 is installed with the low-activity photocatalytic material 214 and the high-activity photocatalytic material 215, so as to realize the segmented absorption and release of nitrogen and prolong the service life of the materials.

[0035] In the embodiment, preferably, the low-activity photocatalytic material 214 adopts a graphite-phase carbon nitride composite material, the high-activity photocatalytic material 215 adopts a graphite-phase carbon nitride composite material doped with nano metal, the low-activity photocatalytic material 214 and the high-activity photocatalytic material 215 enhance the nitrogen adsorption capacity through the porous structure of MOF, and at the same time, the photocatalytic reaction efficiency is improved, the reaction tank 201 adopts a glass fiber reinforced polypropylene with a nano-silica coating sprayed on the inside, and a transparent light cover is arranged above the reaction tank 201. It should be noted that the low-activity photocatalytic material 214 adopts a graphite-phase carbon nitride composite material, which has strong adsorption capacity and reaction stability, is suitable for the initial nitrogen capture stage, and avoids the rapid escape of nitrogen; the high-activity photocatalytic material 215 improves the light response range and electron-hole pair separation efficiency by doping nano metals, significantly accelerating the reaction rate of nitrogen conversion to ammonium nitrogen; the porous characteristics of the MOF provide high specific surface area adsorption sites for nitrogen, improving nitrogen capture efficiency; at the same time, the synergistic effect of the pore structure of the MOF and the photocatalytic material optimizes the reaction path, reduces the generation of by-products, and improves the purity of nitrogen fertilizer; the reaction tank 201 adopts glass fiber reinforced polypropylene, which has a tensile strength of ≥40 MPa and is stable in the pH2-12 range of acid and alkali corrosion, suitable for the complex chemical environment of the rice field water body; the inside of the nano-silicon dioxide coating is sprayed by hydrophobicity and surface modification to reduce reaction liquid residue and microbial attachment, prolong the service life of the reaction tank 201 to more than 5 years, and LED lights are installed inside the reaction tank 201 to provide light in the absence of sunlight and achieve continuous reaction.

[0036] Reference Figure 1 A method for using a photocatalytic nitrogen fertilizer preparation and application integrated device, comprising the following steps: S1, installation and connection of the equipment: the nitrogen fertilizer preparation mechanism 2 is fixedly installed on the field ground or floats in the water body through the floating support 1, and the various devices are connected through the communication pipeline 4 and the sealing joint; S2, nitrogen fertilizer preparation by gas supply: air is input into the nitrogen fertilizer preparation mechanism 2 through the micro air pump 3 and the communication pipeline 4; S3, photocatalytic reaction: when the air is input into the nitrogen fertilizer preparation mechanism 2, a nitrogen fertilizer solution is prepared by gradient photocatalytic material through light reaction; S4, filtration and liquid outlet unit: the nitrogen fertilizer solution is discharged through the liquid outlet pipe 216 at the bottom of the nitrogen fertilizer preparation mechanism 2 and the filter 217, and is directly used for field irrigation.

[0037] A method for using a photocatalytic nitrogen fertilizer preparation and application integrated device, the filter 217 adopts a self-cleaning nano membrane, the surface is coated with a graphene coating, and periodic automatic cleaning is realized through an ultrasonic cleaning device; The self-cleaning nano membrane is provided with three levels: The first level is a microfiltration membrane for filtering large-particle photocatalytic materials; The second level is a nanofiltration membrane for separating ammonium nitrogen and small-particle impurities; The third level is a reverse osmosis membrane for further purifying the nitrogen fertilizer solution; It should be noted that the first stage microfiltration membrane has a pore size of 50-100 nm, which can effectively filter large particles of photocatalytic materials such as g-C3, N4, and MOF composites, preventing clogging and material loss, and ensuring the recycling of photocatalytic materials in the reaction tank 201. The second stage nanofiltration membrane has a pore size of 10-50 nm, which can accurately separate ammonium nitrogen and small particle impurities such as organic debris and microorganisms, improving the purity of the nitrogen fertilizer solution, with an electrical conductivity of ≤500 μS / cm and an NH4 + concentration of ≥150 mg / L. The third stage reverse osmosis membrane has a pore size of <1 nm, which can further remove trace impurities such as heavy metal ions or residual catalysts, achieving high purity of the nitrogen fertilizer solution with an NH4 + purity of ≥98%, meeting the efficient absorption requirements of rice for nitrogen; the graphene coating on the surface of the filter membrane provides hydrophobicity and antibacterial properties, extending the service life of the membrane to more than 10 years; the high electrical conductivity of graphene and the synergistic effect of photocatalytic materials may further improve the charge transfer efficiency of nitrogen adsorption and catalytic reactions, enhancing the overall nitrogen fixation performance; the ultrasonic cleaning device uses high-frequency vibration combined with pulsed water flow, with a vibration frequency of ≥20 kHz, to periodically remove surface contaminants such as organic matter and microorganisms, avoiding frequent manual cleaning and saving maintenance time and labor costs.

[0038] And also provided with solar photovoltaic panel 5, charging converter 6 and storage battery 7, through solar photovoltaic panel 5 to realize receiving the light of sun, generating electric energy, then through charging converter 6 to store electric energy in the inside of storage battery 7, through storage battery 7 to realize power supply for micro air pump 3 and LED lamp.

[0039] Specific embodiments, photocatalytic nitrogen fertilizer preparation and application integrated device field application: Photocatalytic reaction: the reaction tank 201 is made of glass fiber reinforced polypropylene with a nano-silica coating on the inside, which has good light transmission and corrosion resistance. The volume of the reaction tank 201 is 50L, which can be adjusted to 20-200L according to the field area. Gradient photocatalytic materials are installed in the reaction tank 201, and fixed rings 213 are used to fix and install low-activity photocatalytic materials 214 and high-activity photocatalytic materials 215. The gradient photocatalytic materials are fixed and installed in the water body through support plates 212, and a transparent light cover is installed on the mouth of the tank to prevent dust and debris from entering while ensuring the transmission of sunlight into the water body. The micro air pump 3 used for air supply is a direct current diaphragm pump with a power of 3-5 W, which is installed outside the reaction tank 201 and connected to the first aeration ring 206 and the second aeration ring 207 at the bottom of the reaction tank 201 through a corrosion-resistant PVC connecting pipeline 4. The bottom of the first aeration ring 206 and the second aeration ring 207 is connected with aeration nozzles 208 at equal angles. The aeration nozzles 208 adopt a microporous ceramic ball structure with a pore size of 20-50 μm, which can uniformly disperse air into fine bubbles and improve the contact efficiency of nitrogen, water and gradient photocatalytic materials.

[0040] Filtration and liquid outlet: One side of the bottom of the reaction tank 201 is provided with a liquid outlet pipe 216, which is provided with a filter 217 and an electromagnetic control valve 218. The filter 217 adopts a self-cleaning nanometer membrane coated with a graphene coating and is periodically automatically cleaned by an ultrasonic cleaning device. The first stage is a microfiltration membrane for filtering large-particle photocatalytic materials. The second stage is a nanofiltration membrane for separating ammonium nitrogen and small-particle impurities. The third stage is a reverse osmosis membrane for further purifying the nitrogen fertilizer solution, which can smoothly discharge the nitrogen fertilizer solution and effectively retain the gradient photocatalytic materials, ensuring their circulation in the reaction tank 201. Energy supply: The solar photovoltaic panel 5 has a power of 20 W and is installed on the top of the floating support 1 or a ground support. It receives sunlight to generate electric energy, which is stored in the internal battery 7 through the charging converter 6. The battery 7 supplies power to the micro air pump 3 and the LED lamp. When the light is insufficient, the battery 7 supplies power to ensure the continuous operation of the micro air pump 3 and the LED.

[0041] Floating and fixed structure: The floating support 1 is composed of a high-density polyethylene float and a stainless steel frame, which can make the reaction barrel float on the surface of a rice field or a canal. For dry land or fixed position use, the reaction barrel can be placed on the ground or a support.

[0042] Working principle and operation steps: Add clean water to the reaction tank 201 to the rated water level, and add gradient photocatalytic materials configured at a mass ratio of 3 g g-C3N4 / 300 mL water. Start the micro air pump 3, and continuously blow air into the water through the connecting pipeline 4 and the first aeration ring 206 and the second aeration ring 207, and the aeration nozzles 208, so that nitrogen, water and gradient photocatalytic materials are in full contact. Under natural sunlight, the gradient photocatalytic materials absorb light energy to generate electron-hole pairs, and the electrons react with nitrogen molecules to generate ammonia, which dissolves in water to form ammonium nitrogen. Continue aeration for 7-8 days until the ammonium nitrogen concentration in the water reaches a peak of about 3 mg / L, then turn off the micro air pump 3 and let it stand for 2 hours to allow the photocatalytic materials to settle. The electromagnetic control valve 218 is opened, ammonium nitrogen is discharged through the filter 217, and is directly applied to farmland or is connected to an irrigation system; After the reaction tank 201 is supplemented with clean water, the micro air pump 3 is started again, a next production cycle is entered, and the photocatalytic material can be repeatedly used for more than 10 cycles. Field application effect: in a rice field test, the ammonium nitrogen solution produced by the device is used as the only nitrogen source, a 7-day application cycle is adopted, the ammonium nitrogen concentration in the field water is kept stable during the whole growth period, there is no significant difference between the yield and conventional chemical nitrogen fertilizer treatment, P>0.05, but the chemical nitrogen fertilizer consumption is reduced by 100%, the nitrogen utilization efficiency is increased by about 30%, and the ammonia volatilization loss is reduced by more than 40%.

[0043] The above examples are only used to help understand the method of the present application and its core idea. It should be noted that for those skilled in the art, without departing from the principles of the present application, the present application can be improved and modified in several ways, and these improvements and modifications also fall within the scope of the claims of the present application.

Claims

1. An integrated device for photocatalytic nitrogen fertilizer preparation and application, characterized in that: The system includes a floating support (1) which is set in a paddy field. A nitrogen fertilizer preparation mechanism (2) is fixedly installed on the upper part of the floating support (1). The nitrogen fertilizer preparation mechanism (2) includes a reaction tank (201), and is also equipped with a solar photovoltaic panel (5), a charging converter (6), and a storage battery (7). The solar photovoltaic panel (5) receives sunlight to generate electricity, and the storage battery (7) is used to store the electricity.

2. The integrated photocatalytic nitrogen fertilizer preparation and application device according to claim 1, characterized in that: A positioning rod (202) is bonded to the inside of the reaction vessel (201). A return spring (203) is fixedly installed at the upper and lower ends of the positioning rod (202). A lifting ring (204) is fixedly connected between the two return springs (203). The lifting ring (204) is movably installed on the positioning rod (202).

3. The integrated photocatalytic nitrogen fertilizer preparation and application device according to claim 2, characterized in that: Four positioning plates (205) are welded to the outside of the lifting ring (204). A first aeration ring (206) and a second aeration ring (207) are fixedly installed on the four positioning plates (205). Aeration nozzles (208) are connected at equal angles to the bottom of the first aeration ring (206) and the second aeration ring (207).

4. The integrated photocatalytic nitrogen fertilizer preparation and application device according to claim 3, characterized in that: A shaft (209) is fixedly installed on the four positioning plates (205). The shaft (209) is located between the first aeration ring (206) and the second aeration ring (207). A turbine blade (210) is movably installed on the upper end of the shaft (209).

5. The integrated photocatalytic nitrogen fertilizer preparation and application device according to claim 4, characterized in that: A diversion pipe (211) is connected between the first aeration ring (206) and the second aeration ring (207). A connecting pipe (4) is sealed in the middle of the diversion pipe (211). The other end of the connecting pipe (4) is sealed to the air supply port of the micro air pump (3). The micro air pump (3) is electrically connected to the battery (7).

6. The integrated photocatalytic nitrogen fertilizer preparation and application device according to claim 5, characterized in that: Four support plates (212) are fixedly bonded to the bottom of the reaction vessel (201). The upper ends of the four support plates (212) are fixedly connected to a fixing ring (213). Low-activity photocatalytic material (214) and high-activity photocatalytic material (215) are fixedly installed inside the fixing ring (213). The low-activity photocatalytic material (214) is located below the high-activity photocatalytic material (215).

7. The integrated photocatalytic nitrogen fertilizer preparation and application device according to claim 6, characterized in that: The bottom side of the reaction vessel (201) is connected to a liquid outlet pipe (216), a filter (217) is installed on the liquid outlet pipe (216), and an electromagnetic control valve (218) is fixedly installed at the end of the liquid outlet pipe (216).

8. The integrated photocatalytic nitrogen fertilizer preparation and application device according to claim 7, characterized in that: The low-activity photocatalytic material (214) is a graphite-phase carbon nitride composite material, and the high-activity photocatalytic material (215) is a graphite-phase carbon nitride composite material doped with nano-metals. The low-activity photocatalytic material (214) and the high-activity photocatalytic material (215) enhance nitrogen adsorption capacity through the porous structure of MOF, and at the same time improve photocatalytic reaction efficiency. The reaction vessel (201) is made of glass fiber reinforced polypropylene with a nano-silica coating sprayed on the inside. The reaction vessel (201) is provided with a transparent light-transmitting cover.

9. A method for using an integrated photocatalytic nitrogen fertilizer preparation and application device, characterized in that: Includes the following steps: S1. Installation and connection of equipment: The nitrogen fertilizer preparation mechanism (2) is fixedly installed on the ground in the field or floated in the water through the floating support (1), and the various devices are connected through the connecting pipe (4) and the sealing joint; S2, Nitrogen fertilizer preparation by supplying air: Air is supplied to the nitrogen fertilizer preparation mechanism (2) through a micro air pump (3) and a connecting pipe (4); S3, Photocatalytic reaction: When air is input into the nitrogen fertilizer preparation mechanism (2), nitrogen fertilizer solution is prepared by photocatalysis through gradient photocatalytic materials; S4, Filtration and Discharge Unit: Nitrogen fertilizer solution is discharged through the discharge pipe (216) and filter (217) at the bottom of the nitrogen fertilizer preparation mechanism (2) and used directly for field irrigation.

10. The method of using the integrated photocatalytic nitrogen fertilizer preparation and application device according to claim 9, characterized in that: The filter (217) uses a self-cleaning nanomembrane with a graphene coating on its surface, and is periodically and automatically cleaned by an ultrasonic cleaning device. The self-cleaning nanofilm is configured with three levels: The first stage is a microfiltration membrane, used to filter large-particle photocatalytic materials; The second stage is a nanofiltration membrane, used to separate ammonium nitrogen from small particulate impurities; The third stage is a reverse osmosis membrane, used for further purification of the nitrogen fertilizer solution.

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