A method and device for synthesizing oxygen vacancy nano-tin oxide using waste raw materials

Abstract

The present invention provides a method and apparatus for synthesizing oxygen-vacancy nano-tin oxide using waste raw materials. The method uses industrial and agricultural waste as raw materials and realizes the preparation of oxygen-vacancy nano-tin oxide through self-propagating high-temperature synthesis technology and the regulation of a flowing mixed atmosphere with an oxidizing function. The nano-tin oxide product prepared by the present invention has the advantages of high purity, good dispersibility, adjustable oxygen vacancy content, and good photocatalytic performance. While proposing a method for preparing nano-tin oxide with adjustable oxygen vacancy content, the method and apparatus provided by the present invention reduce the energy consumption and raw material costs of existing oxygen-vacancy nano-tin oxide production, improve its production efficiency, and achieve safe disposal of waste, greatly reducing environmental pressure. It has good economic and environmental benefits and has broad prospects for promotion and application.

Description

Technical Field

[0001] The present invention belongs to the technical field of nano material synthesis and solid waste resource utilization, and specifically relates to a method for synthesizing oxygen vacancy nano tin oxide using waste raw materials, and also relates to a device for synthesizing oxygen vacancy nano tin oxide using waste raw materials. Background Art

[0002] Tin oxide (SnO2) is an important wide-bandgap (3.6 eV) n-type semiconductor oxide. Nanotin oxide, with its unique optoelectronic properties, gas sensitivity, and chemical stability, shows broad application prospects in transparent electrodes, gas sensors, lithium-ion batteries, and photoelectrocatalysis. Oxygen vacancies are the main type of defect in tin oxide nanostructures. They provide a local high energy level in the internal band gap, which can effectively capture electrons in the valence band for electronic transitions, thereby significantly affecting the semiconductor properties of the material. Therefore, precisely controlling the oxygen vacancy content of nanotin oxide materials is particularly important for improving their performance.

[0003] Numerous methods for preparing nanotin oxide have been reported in the literature, including the hydrothermal synthesis method proposed in patent application CN1528671A; the microemulsion synthesis method proposed by Pan Qingyi et al. (Journal of Inorganic Materials, 1999, 14: 83-88); and the sol-gel and template synthesis methods described in patent application CN106629822B. These methods suffer from complex processes and demanding equipment and operational requirements. To address these issues, current research has applied self-propagating high-temperature synthesis (SHT), known for its advantages of fewer steps, shorter processes, simpler technology, and higher product quality, to the preparation of nanotin oxide. For example, patent application CN101671050A discloses a method for preparing nanotin oxide materials using an exothermic reaction. Xu Bingshe et al. (Metallic Materials and Engineering, 2007, S2: 492-495) prepared tin oxide nanowires via combustion synthesis and thermal explosion deformation. However, the above preparation method cannot achieve the preparation of nano-tin oxide with controllable oxygen vacancy content, and the tin sources it relies on, including chemical reagents such as tin, tin oxide, tin salts and stannous salts, have high purchase costs and low raw material utilization rates, which limits the promotion of large-scale industrial production.

[0004] Currently, there are many studies on methods for creating oxygen vacancies in nanotin oxide materials. For example, Li Fuping et al. (Semiconductor Optoelectronics, 2015, 36(03): 425-430) proposed that annealing treatment would affect the oxygen vacancy defects of the material; He Zhenkun (Northeastern University, 2019) proposed the use of in-situ molten salt oxidation to prepare nanotin oxide containing oxygen vacancies and discussed its formation mechanism; Yu Yanqiu (Wuhan University of Technology, 2022) proposed that doping in the material would also affect its oxygen vacancy concentration. However, the above methods have limited ability to control the oxygen vacancy content in the nanotin oxide product. Existing processes capable of regulating oxygen vacancies in materials include the electrochemical method described in patent CN112939053A, which controls the oxygen vacancy concentration in oxides by adjusting the composition of the electrolyte; patent CN113526567A discloses a method for preparing metal oxides with oxygen vacancies through controlled acid etching; and patent CN106564892A produces transition metal oxides with varying degrees of reduction by controlling the concentration, freeze-drying duration, and microwave combustion treatment duration. These methods generally suffer from complex production processes, high energy consumption, and demanding operating conditions.

[0005] Based on the above reasons, a self-propagating high-temperature synthesis method for nano-tin oxide using industrial and agricultural waste as raw materials is provided, which can achieve the regulation of the oxygen vacancy content of the product. While preparing nano-tin oxide with low energy consumption and low cost, it can also achieve the rapid disposal of industrial and agricultural waste. This is of great significance for promoting scientific and technological progress and environmental protection, and is also a technical problem that needs to be solved urgently. Summary of the Invention

[0006] One of the purposes of the present invention is to provide a low-cost, low-energy method for synthesizing nano-tin oxide with controllable oxygen vacancy content using solid waste as raw materials.

[0007] A second object of the present invention is to provide a device for synthesizing oxygen vacancy nano-tin oxide using waste raw materials.

[0008] The technical solution adopted by the present invention to achieve one of the objectives is to provide a method for synthesizing oxygen vacancy nano-tin oxide using waste raw materials, comprising the following steps:

[0009] S1. Mixing tin source waste with solid waste, grinding and drying to obtain a mixture; adding tar pitch to the mixture and mixing uniformly, and then pressing into a briquette;

[0010] The solid waste includes: industrial solid waste that contains or can generate oxides or sulfides corresponding to aluminum, silicon, iron, manganese, and calcium through self-propagating reactions; industrial solid waste that contains or can generate metal elements or alloys with a density greater than that of tin through self-propagating reactions; and agricultural solid waste that can assist the system in releasing heat and generate a certain amount of gas;

[0011] S2. Placing the briquette in a reactor under a flowing atmosphere, wherein the flowing atmosphere is a mixture of nitrogen, oxygen, and argon; igniting the briquette to cause a self-propagating reaction to generate tin liquid; and the tin liquid escapes from the reactor and is oxidized under the action of the high temperature and high pressure generated by the self-propagating reaction and the flowing atmosphere;

[0012] S3. Collect the products generated by oxidation of the tin liquid to obtain oxygen vacancy nano-tin oxide.

[0013] The overall concept of the present invention is as follows:

[0014] The present invention provides a method for synthesizing oxygen vacancy nano-tin oxide using solid waste raw materials. The method utilizes the chemical reaction and phase change process of the solid waste raw materials to control the formation, liquefaction, gasification, migration, oxidation and solidification of the tin source to achieve the preparation of oxygen vacancy nano-tin oxide.

[0015] In the above method, the types of solid waste must first be screened. The present invention utilizes industrial solid wastes of specific compositions. Among these, industrial solid wastes that contain or can generate oxides or sulfides corresponding to aluminum, silicon, iron, manganese, or calcium through a self-propagating reaction can form partially molten, interconnected, porous composite scum during the reaction, providing pressure and channels for the tin to disperse and escape from the reactor. Industrial solid wastes that contain or can generate metal elements or alloys with a density greater than that of elemental tin through a self-propagating reaction can form an alloy melt with a density far greater than that of tin during the reaction, allowing it to quickly settle below the molten tin and, together with the scum above the molten tin, form a closed micro-zone, providing sufficient injection pressure for the tin to escape.

[0016] During the self-propagating reaction, elemental tin, in the form of liquid tin, is ejected under pressure at a localized, transiently high temperature. Entrained by generated gases such as carbon dioxide and water vapor, it escapes the reactor and undergoes oxidation and non-equilibrium solidification in a flowing atmosphere of a mixture of nitrogen, oxygen, and argon. Furthermore, by adjusting the composition and flow rate of the mixed gas, the degree of tin oxidation, oxidation, and cooling times can be controlled, thereby regulating the oxygen vacancies in the resulting product. Ultimately, the solidified tin oxide product is transported by the airflow and collected to yield the desired product.

[0017] Furthermore, in step S1, the industrial solid waste includes a combination of one or more of aluminum alloy processing waste metal chips, dye industry acidification copper slag, hematite tailings, iron sludge, lime fluoride gypsum, and electrolytic manganese plant tailings. The main components of aluminum alloy processing waste metal chips are Al; the main components of dye industry acidification copper slag are CuO and CuSO4·5H2O; the main components of hematite tailings are Fe2O3; the main components of iron sludge are Fe3O4, Fe2O3, FeO, and Fe; the main components of lime fluoride gypsum are CaSO4 and water of crystallization; and the main components of electrolytic manganese plant tailings are MnO2, MnSO4, CaSO4, and SiO2.

[0018] Furthermore, the tin source waste includes one or more combinations of processing waste tin, tin paste, solder waste, and tin plating waste, and the main components of the above tin source waste include Sn, Pb and SnO.

[0019] Furthermore, in step S1, among the solid wastes, agricultural solid waste includes dead branches and leaves and / or straw. The main components of this type of agricultural solid waste are organic matter such as cellulose and lignin, which can release heat through a relatively slow combustion auxiliary system and produce a certain amount of gas. The present invention adds a certain proportion of agricultural solid waste to the raw material mixture. On the one hand, agricultural solid waste burns slowly compared to industrial products with similar components such as graphite and carbon powder, which can compensate for the cooling of the system after the heat release slows down the self-propagating reaction; on the other hand, the dry agricultural solid waste contains many pores and is densely filled with air, making it easier to burn than chemical reagents with the same composition.

[0020] The industrial solid waste and agricultural solid waste used in the present invention can generate a certain amount of gas during the reaction, and the product does not react with other substances. While increasing the spraying pressure of the tin liquid, it helps to disperse and atomize the tin liquid, so that it forms droplets as small as possible.

[0021] Preferably, in step S1, the mixture is composed of the following raw materials in parts by weight: 13.5-64.5 parts of tin source waste, 5.6-22.4 parts of aluminum alloy processing waste metal chips, 23.7-48.5 parts of dye industry acidified copper slag, 37.3-60.6 parts of hematite tailings, 27.6-44.7 parts of iron mud, 17.4-48.9 parts of lime fluoride gypsum, 20.0-42.5 parts of electrolytic manganese plant tailings, and 0.8-28.6 parts of agricultural solid waste.

[0022] Preferably, in step S1, the industrial solid waste is ground and passed through a 200-300 mesh sieve so that its particle size does not exceed 0.075 mm, and the agricultural solid waste is ground and passed through a 10-50 mesh sieve so that its particle size is not greater than 2 mm.

[0023] In the present invention, by optimizing and adjusting the ratio of the various components in the raw materials and the particle size distribution of the raw materials, a balance is achieved between the released heat and the heat absorbed by the products, ensuring that the tin liquid can be melted and the local temperature rise can form a sufficient instantaneous pressure, while preventing other products from escaping and being mixed into the tin liquid to form impurities. In addition, the appropriate ratio and particle size distribution can achieve the regulation of the pressure in the reactor, while controlling the injection amount and injection speed of the tin liquid, and avoiding excessive pressure that causes the alloy liquid below the tin liquid to be ejected and mixed into the tin liquid, thereby affecting the purity of the tin liquid.

[0024] Furthermore, in step S1, the tar pitch includes wood tar and asphalt, and the amount of wood tar added to the mixture is 350-550 mL / kg, and the amount of asphalt added to the mixture is 0-150 mL / kg. The main components of wood tar and asphalt are organic compounds such as phenols and alcohols. During the reaction process, various chemical reactions may occur between the various waste components, including but not limited to thermite reaction, dehydration reaction of hydrates, combustion reaction of organic matter, etc. These reactions will release a large amount of heat and be accompanied by the generation of gas. The addition of wood tar and asphalt not only helps the bonding and molding of the raw material powder and completes the blanking, but also can further increase the total heat release and gas production of the system through the combustion reaction.

[0025] The reaction types that may be involved in the method provided by the present invention are as follows:

[0026] Al+M x O y →Al2O3+M (M is a metal element such as Cu, Fe, or Mn)

[0027] Al+CaSO4→CaAl2O4+CaS+SO2(g)

[0028] Al+CaSO4→Al2O3+CaS+SO2(g)

[0029] Al+MnSO4→Al2O3+MnS+SO2(g)

[0030] Al+SnO→Al2O3+Sn

[0031] CuSO4·5H2O→CuSO4+5H2O(g)

[0032] CaSO4·2H2O→CaSO4·1 / 2H2O+3 / 2H2O(g)

[0033] CaSO4·1 / 2H2O→CaSO4+1 / 2H2O(g)

[0034] CuSO4→CuO+SO3(g)

[0035] Cx H y +O2→CO2(g)+H2O(g)

[0036] C x H y O z +O2→CO2(g)+H2O(g)

[0037] In addition, during the reaction process, as the temperature changes, the system will undergo a series of complex phase transitions, including not only physical changes of raw materials, intermediates, and reaction products, but also eutectic reactions between metal oxides. Specifically, these phase transitions may include but are not limited to:

[0038] Sn(s) Sn(l)

[0039] Pb(s) Pb(l)

[0040] Cu(s) Cu(l)

[0041] Mn(s) Mn(l)

[0042] SiO2-Al2O3·SiO2-Fe2O3·Al2O3(s) SiO2-Al2O3·SiO2(s)+L

[0043] Al2O3-Al2O3·SiO2-Fe2O3·Al2O3(s) Al2O3-Al2O3·SiO2(s)+L

[0044] Al2O3(s)+CaO(s)+SiO2(s) CaO·Al2O3·2SiO2(l)

[0045] Fe(s) Fe(l)

[0046] Fe2O3(s) Fe2O3(l)

[0047] Al2O3(s)+SiO2(s) Al2O3·SiO2(l)

[0048] Al2O3(s)+CaO(s) CaO·6Al2O3(l)

[0049] Al2O3(s) Al2O3(l)

[0050] CaO(s)+SiO2(s) 2CaO·SiO2(l)

[0051] CaO(s) CaO(l)

[0052] In the above reaction formula, L represents the mixed liquid phase of the product.

[0053] During the various reaction stages or thermal environments of the present invention, the solid waste feedstock and the resulting elemental tin exist as liquid tin. Due to gravity and density stratification, the liquid tin converges in the middle layer of the reaction pool, where it is covered by a porous scum composed of a less dense eutectic solid solution of metal oxides and aluminosilicates. Simultaneously, it lies above a higher-density alloy liquid composed of metals such as iron, copper, manganese, and lead. Under localized, transient high temperatures, it is pressurized and ejected, entrained by generated gases such as carbon dioxide and water vapor, and escapes the reactor. Upon exiting the reactor, the elemental tin undergoes oxidation and nonequilibrium solidification in the flowing atmosphere formed by the mixed gas.

[0054] Furthermore, by pre-controlling the chamber atmosphere composition and gas extraction rate, the degree of tin oxidation, oxidation, and cooling time can be controlled, thereby regulating the oxygen vacancies in the resulting product. Ultimately, the solidified tin oxide product is transported with the airflow and captured by a collection device, completing the product collection.

[0055] Furthermore, in step S1, the compact is pressed at a pressure of 2-10 MPa and for a time of 60-120 seconds. Preferably, the compact is a cylindrical block with a height-to-diameter ratio of 1:2-1:6.

[0056] Furthermore, in step S2, the volume fraction of the briquette in the reactor is 0.36-1.6 kg / L. In the present invention, appropriate briquette pressing pressure, pressing time, external dimensions, and charging volume fraction are selected to ensure that the raw material particles are adjacent to each other, that the combustion wave after ignition is not easily extinguished during the self-propagating transmission process, and that sufficient pores are left between the raw material particles and around the briquette to allow for sufficient aerobic combustion.

[0057] Furthermore, in step S2, selecting a flowing atmosphere composition and mixed gas flow rate that matches the tin liquid injection volume and injection velocity can control the dispersion, concentration, ambient pressure, oxygen content, and residence time of the tin liquid in the air within the chamber, thereby adjusting the degree of tin oxidation, oxidation, and cooling time, thereby achieving regulation of oxygen vacancies in the resulting product. Preferably, the mixed gas composition, by volume, is 79.2-96.2 parts nitrogen, 4.1-21.3 parts oxygen, and 0.9-1.1 parts argon; and the mixed gas flow rate is 200-1000 mL / min.

[0058] The method provided by this invention for synthesizing oxygen-vacancy nanotin oxide from solid waste raw materials fully leverages the advantages of self-propagating high-temperature synthesis technology. Through the nanotin oxide preparation system and process design, the oxygen vacancy content of the product can be controlled without the introduction of any templates or harsh conditions. Furthermore, this method significantly reduces the raw material cost of nanotin oxide preparation while achieving large-scale disposal of industrial and agricultural waste.

[0059] In some preferred embodiments, the purity of the nano-tin oxide with oxygen vacancies prepared by the present invention is 84.94%-99.9%, the grain size is 12.14-75.67 nm, and the oxygen vacancy is 24.36%-36.77%.

[0060] Furthermore, the nano-tin oxide containing oxygen vacancies prepared by the present invention also has good photocatalytic performance, and the photocatalytic degradation rate of nitrite can reach 59.01%-70.23% under suitable conditions.

[0061] The technical solution adopted by the present invention to achieve the second purpose is: to provide a device for synthesizing oxygen vacancy nano-tin oxide using waste raw materials based on the method described in one of the purposes of the present invention, which includes: a gas storage source, a gas transmission pipe, an atmosphere mixing device, a reaction chamber, a pressure detector, a laser igniter, a reactor, a flow rate control device, a collection box, an electrostatic dust removal device and an exhaust pipe.

[0062] Among them, the gas storage source is used to store the raw gas (nitrogen, oxygen and argon) of the mixed gas required for the reaction; the raw gas enters the atmosphere mixing device through the gas pipe, and a mixed gas of a specific proportion is obtained by controlling the gas partial pressure; the mixed gas enters from the inlet of the reaction chamber and flows out from the outlet of the reaction chamber. A flow rate control device is provided at the outlet of the reaction chamber to adjust the flow rate of the mixed gas.

[0063] A reactor is provided at the bottom center of the reaction chamber. The reactor is used to accommodate raw material blocks and provide a place for self-propagating reaction. An air pressure detector and a laser igniter are provided above the reactor. The air pressure detector is used to detect the air pressure changes in the reaction chamber to ensure that high pressure or negative pressure does not appear in the reaction chamber. The laser igniter is used to ignite the blocks and trigger a self-propagating reaction. The electrostatic precipitator is used to capture the solidified tin oxide products transferred with the air flow. A collection box for collecting the products is provided below the electrostatic precipitator, and an exhaust pipe is provided at the end of the collection box.

[0064] Compared with the prior art, the present invention has the following beneficial effects:

[0065] (1) The present invention provides a method for synthesizing oxygen-vacancy nano-tin oxide using solid waste raw materials. This method utilizes the chemical reaction and phase change process of the solid waste raw materials to control the formation, liquefaction, vaporization, migration, oxidation, and solidification of the tin source, thereby achieving the preparation of oxygen-vacancy nano-tin oxide. This method can achieve targeted regulation of the oxygen vacancy content of the nano-tin oxide product by adjusting process parameters such as the raw material system, mixed atmosphere composition, and atmosphere flow rate. The process is simple, energy-efficient, and environmentally friendly.

[0066] (2) The oxygen vacancy nano-tin oxide prepared by the method provided by the present invention has a purity of 84.94%-99.9%, a grain size of 12.14-75.67 nm, an oxygen vacancy content of 24.36%-36.77%, and has good photocatalytic performance. Under suitable conditions, the photocatalytic degradation rate of nitrite can reach 59.01%-70.23%.

[0067] (3) The method and device provided by the present invention for synthesizing oxygen vacancy nano-tin oxide using solid waste raw materials can obtain nano-tin oxide products with good performance using industrial and agricultural waste as raw materials. This not only significantly reduces the raw material cost of preparing nano-tin oxide, but also achieves the safe disposal of waste. For every ton of oxygen vacancy nano-tin oxide product produced, 21.2-115.1 tons of waste can be disposed of, which greatly reduces the pressure on environmental protection and has broad prospects for promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Figure 1 A schematic diagram of the structure of a device for synthesizing oxygen vacancy nano-tin oxide using waste raw materials according to an embodiment of the present invention;

[0069] Figure 2 This is the XRD pattern of the oxygen vacancy nano-tin oxide sample prepared in Example 1 of the present invention;

[0070] Figure 3 This is a Raman graph of the oxygen vacancy nano-tin oxide sample prepared in Example 2 of the present invention;

[0071] Among them, 1-gas storage source; 2-gas transmission pipe; 3-atmosphere mixing device; 4-reaction chamber; 5-air pressure detector; 6-laser igniter; 7-reactor; 8-raw material block; 9-flow rate control device; 10-collection box; 11-electrostatic dust removal device; 12-exhaust pipe. DETAILED DESCRIPTION

[0072] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0073] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0074] The present invention provides a method for synthesizing oxygen vacancy nano-tin oxide using waste raw materials. The device structure diagram used in this method is as follows: Figure 1 It includes: a gas storage source 1, a gas transmission pipe 2, an atmosphere mixing device 3, a reaction chamber 4, a pressure detector 5, a laser igniter 6, a reactor 7, a flow rate control device 9, a collection box 10, an electrostatic dust removal device 11 and an exhaust pipe 12.

[0075] Among them, the gas storage source 1 is used to store the raw gas (nitrogen, oxygen and argon) of the mixed gas required for the reaction; the raw gas enters the atmosphere mixing device 3 through the gas pipeline 2, and a mixed gas of a specific proportion is obtained by controlling the gas partial pressure; the mixed gas enters from the inlet of the reaction chamber 4 and flows out from the outlet of the reaction chamber. A flow rate control device 9 is provided at the outlet of the reaction chamber to adjust the flow rate of the mixed gas.

[0076] A reactor 7 is provided at the center of the bottom of the reaction chamber. The reactor is used to accommodate the raw material blocks and provide a place for self-propagating reaction. A pressure detector 5 and a laser igniter 6 are provided above the reactor. The pressure detector is used to detect the pressure changes in the reaction chamber to ensure that high pressure or negative pressure does not occur in the reaction chamber. The laser igniter is used to ignite the blocks and trigger a self-propagating reaction. An electrostatic precipitator 11 is used to capture the solidified tin oxide products transferred with the airflow. A collection box 10 for collecting the products is provided below the electrostatic precipitator, and an exhaust pipe 12 is provided at the end of the collection box.

[0077] The present invention is further described below with reference to specific examples. Examples 1-5 show that the present invention, through analysis of the composition, output, and storage and transportation costs of typical waste containing target components, combined with a large number of experimental studies, thermodynamic calculations, and kinetic modeling, ultimately determines the existing raw material system composition scheme and oxygen vacancy nano-tin oxide preparation process parameter combination. These examples are for illustration only and are not intended to limit the present invention.

[0078] The main raw materials and parameters involved in each embodiment of the present invention are shown in Table 1 and Table 2 below.

[0079] Table 1

[0080]

[0081] In the above table, industrial solid waste raw materials are ground and passed through a 200-300 mesh sieve to make their particle size no more than 0.075mm, and agricultural solid waste corn straw is ground and passed through a 10-50 mesh sieve to make its particle size no more than 2mm.

[0082] Table 2

[0083]

[0084] Example 1

[0085] This embodiment provides a method for synthesizing oxygen vacancy nano-tin oxide using waste raw materials, comprising the following steps:

[0086] Step 1: Aluminum alloy processing waste metal chips, dye industry acidified copper slag, hematite tailings, iron mud, lime fluor gypsum, electrolytic manganese plant tailings, and processing waste tin are passed through a 200-mesh sieve to make the particle size not exceed 0.075 mm, and corn straw is passed through a 30-mesh sieve to make the particle size not exceed 0.6 mm. After drying, 1 kg of solid waste raw materials are weighed according to a mass ratio of 22.4:48.5:60.6:44.7:48.9:42.5:45.9:0.8, 350 mL of wood tar and 150 mL of asphalt are added, and the mixture is evenly mixed. The raw material blocks 8 with a height-to-diameter ratio of 1:2 are obtained under a pressure of 10 MPa and a pressure holding time of 60 seconds.

[0087] Step 2: After the briquette obtained in step 1 is placed in the center of the reactor 7 at a raw material volume ratio of 0.36 kg / L, a mixed gas of nitrogen, oxygen, and argon is added in the atmosphere mixing device 3 at a volume ratio of 82.8:16.7:1.1, and the extraction flow rate is controlled to be 200 mL / min. When the pressure in the reaction chamber reaches the preset value, the briquette is ignited using the laser igniter 6 to cause a reaction;

[0088] Step 3: After the reaction is completed, the products are collected by means of an electrostatic dust removal device 11 to obtain an oxygen vacancy nano-tin oxide product in a collection box 10.

[0089] The oxygen vacancy nano-tin oxide prepared in this embodiment has a purity of 84.94%, an oxygen vacancy content of 35.39%, and a grain size of 15.22-52.32 nm. The XRD test results are as follows: Figure 2 As shown in the figure, under the conditions of initial nitrite concentration of 2.5 mg / L, pH of 6, nano-tin oxide feed ratio of 0.1 g / L, temperature of 15°C, and photoreaction time of 8 min, the nitrite purification rate can reach 70.23%, indicating good photocatalytic performance.

[0090] Example 2

[0091] This embodiment provides a method for synthesizing oxygen vacancy nano-tin oxide using waste raw materials, comprising the following steps:

[0092] Step 1: Aluminum alloy processing waste metal chips, dye industry acidified copper slag, hematite tailings, iron mud, lime fluor gypsum, electrolytic manganese plant tailings, and processing waste tin are passed through a 250-mesh sieve to make the particle size no more than 0.065 mm, and corn straw is passed through a 10-mesh sieve to make the particle size no more than 2 mm. After drying, 1 kg of solid waste raw materials are weighed according to a mass ratio of 5.6:23.7:37.3:27.6:17.4:20:24:16.7, 375 mL of wood tar and 75 mL of asphalt are added, and the mixture is evenly mixed. The raw material blocks 8 with a height-to-diameter ratio of 1:4 are obtained under a pressure of 6 MPa and a pressure holding time of 90 seconds.

[0093] Step 2: After the briquette obtained in step 1 is placed in the center of the reactor 7 at a raw material volume ratio of 1.0 kg / L, a mixed gas of nitrogen, oxygen, and argon is added in the atmosphere mixing device 3 at a volume ratio of 90:10.3:1, and the extraction flow rate is controlled to be 500 mL / min. When the pressure in the reaction chamber reaches the preset value, the briquette is ignited using the laser igniter 6 to cause a reaction;

[0094] Step 3: After the reaction is completed, the products are collected by means of an electrostatic dust removal device 11 to obtain oxygen vacancy nano-tin oxide products in a collection box 10.

[0095] The oxygen vacancy nano-tin oxide prepared in this embodiment has a purity of 98.04%, an oxygen vacancy content of 27.98%, and a grain size of 15.17-33.54 nm. The Raman test results are as follows: Figure 3 As shown; under the conditions of initial nitrite concentration of 2.5 mg / L, pH of 6, nano-tin oxide feed ratio of 0.1 g / L, temperature of 15°C, and photoreaction time of 8 min, the nitrite purification rate can reach 64.23%, indicating good photocatalytic performance.

[0096] Example 3

[0097] This embodiment provides a method for synthesizing oxygen vacancy nano-tin oxide using waste raw materials, comprising the following steps:

[0098] Step 1: Aluminum alloy processing waste metal chips, dye industry acidified copper slag, hematite tailings, iron mud, lime fluor gypsum, electrolytic manganese plant tailings, and processing waste tin are passed through a 250-mesh sieve to make the particle size no more than 0.065 mm, and corn straw is passed through a 10-mesh sieve to make the particle size no more than 2 mm. After drying, 1 kg of solid waste raw materials are weighed according to a mass ratio of 7.8:31.6:40.5:35:30:20:13.5:16.7, 375 mL of wood tar and 75 mL of asphalt are added, and the mixture is evenly mixed. The raw material blocks 8 with a height-to-diameter ratio of 1:4 are obtained under a pressure of 6 MPa and a pressure holding time of 90 seconds.

[0099] Step 2: After the briquette obtained in step 1 is placed in the center of the reactor 7 at a raw material volume ratio of 1.0 kg / L, a mixed gas of nitrogen, oxygen, and argon is added in the atmosphere mixing device 3 at a volume ratio of 90:10.3:1, and the extraction flow rate is controlled to be 500 mL / min. When the pressure in the reaction chamber reaches the preset value, the briquette is ignited using the laser igniter 6 to cause a reaction;

[0100] Step 3: After the reaction is completed, the products are collected by means of an electrostatic dust removal device 11 to obtain oxygen vacancy nano-tin oxide products in a collection box 10.

[0101] The oxygen vacancy nano-tin oxide prepared in this embodiment has a purity of 93.63%, an oxygen vacancy content of 32.23%, and a grain size of 34.01-75.67 nm. Under the conditions of an initial nitrite concentration of 2.5 mg / L, a pH of 6, a nano-tin oxide feed ratio of 0.1 g / L, a temperature of 15°C, and a photoreaction time of 8 min, the nitrite purification rate can reach 66.61%, indicating good photocatalytic performance.

[0102] Example 4

[0103] This embodiment provides a method for synthesizing oxygen vacancy nano-tin oxide using waste raw materials, comprising the following steps:

[0104] Step 1: Aluminum alloy processing waste metal chips, dye industry acidified copper slag, hematite tailings, iron mud, lime fluor gypsum, electrolytic manganese plant tailings, and processing waste tin are passed through a 250-mesh sieve to a particle size not exceeding 0.065 mm. Corn straw is passed through a 10-mesh sieve and dried to a particle size not exceeding 2 mm. 1 kg of solid waste raw materials is weighed according to a mass ratio of 5.6:23.7:37.3:27.6:17.4:20:24:16.7, 375 mL of wood tar and 75 mL of asphalt are added, and the mixture is evenly mixed. The raw material blocks 8 with a height-to-diameter ratio of 1:4 are obtained by pressing at a pressure of 6 MPa and holding the pressure for 90 seconds.

[0105] Step 2: After the briquette obtained in step 1 is placed in the center of the reactor 7 at a raw material volume ratio of 1.0 kg / L, a mixed gas of nitrogen, oxygen, and argon is added in the atmosphere mixing device 3 at a volume ratio of 96.2:4.1:0.9, and the extraction flow rate is controlled to 800 mL / min. When the pressure in the reaction chamber reaches the preset value, the briquette is ignited using the laser igniter 6 to cause a reaction;

[0106] Step 3: After the reaction is completed, the products are collected by means of an electrostatic dust removal device 11 to obtain oxygen vacancy nano-tin oxide products in a collection box 10.

[0107] The oxygen vacancy nano-tin oxide prepared in this embodiment has a purity of 90.83%, an oxygen vacancy content of 36.77%, and a grain size of 12.14-62.33 nm. Under the conditions of an initial nitrite concentration of 2.5 mg / L, a pH of 6, a nano-tin oxide feed ratio of 0.1 g / L, a temperature of 15°C, and a photoreaction time of 8 min, the nitrite purification rate can reach 65.56%, indicating good photocatalytic performance.

[0108] Example 5

[0109] This embodiment provides a method for synthesizing oxygen vacancy nano-tin oxide using waste raw materials, comprising the following steps:

[0110] Step 1: Aluminum alloy processing waste metal chips, dye industry acidified copper slag, hematite tailings, iron mud, lime fluor gypsum, electrolytic manganese plant tailings, and processing waste tin are passed through a 300-mesh sieve to a particle size not exceeding 0.055 mm, and corn straw is passed through a 50-mesh sieve and dried to a particle size not exceeding 0.3 mm. 1 kg of solid waste raw materials are weighed according to a mass ratio of 16:36:49:35.6:33:31:39:28.6, 550 mL of wood tar are added, and the mixture is evenly mixed. The raw material blocks 8 with a height-to-diameter ratio of 1:6 are obtained by pressing at a pressure of 2 MPa and holding the pressure for 120 seconds;

[0111] Step 2: After the briquette obtained in step 1 is placed in the center of the reactor 7 at a raw material volume ratio of 1.6 kg / L, a mixed gas of nitrogen, oxygen, and argon is added in the atmosphere mixing device 3 at a volume ratio of 79.2:21.3:1, and the extraction flow rate is controlled to be 1000 mL / min. When the pressure in the reaction chamber reaches the preset value, the briquette is ignited using the laser igniter 6 to cause a reaction;

[0112] Step 3: After the reaction is completed, the products are collected by means of an electrostatic dust removal device 11 to obtain oxygen vacancy nano-tin oxide products in a collection box 10.

[0113] The oxygen vacancy nano-tin oxide prepared in this embodiment has a purity of 99.9%, an oxygen vacancy content of 24.36%, and a grain size of 24.85-46.45 nm. Under the conditions of an initial nitrite concentration of 2.5 mg / L, a pH of 6, a nano-tin oxide feed ratio of 0.1 g / L, a temperature of 15°C, and a photoreaction time of 8 min, the nitrite purification rate can reach 59.01%, indicating good photocatalytic performance.

[0114] The above are only preferred embodiments of the present invention and do not limit the implementation mode and protection scope of the present invention. For those skilled in the art, it should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the contents of the present invention specification should be included in the protection scope of the present invention.

Claims

1. A method for synthesizing oxygen vacancy nano-tin oxide using waste raw materials, characterized in that: The following steps are involved: S1. Mixing tin source waste with solid waste, grinding and drying the mixture to obtain a mixture; adding tar pitch to the mixture and mixing them evenly, and then pressing them into blocks; the solid waste includes: industrial solid waste that contains or can generate oxides or sulfides corresponding to aluminum, silicon, iron, manganese, and calcium through self-propagating reaction, industrial solid waste that contains or can generate metal elements or alloys with a density greater than that of tin through self-propagating reaction, and agricultural solid waste that can assist the system in releasing heat and generate a certain amount of gas; the tin source waste includes A combination of one or more of solder paste, solder waste, and tin plating waste; the mixture is composed of the following raw materials in parts by weight: 13.5-64.5 parts of tin source waste, 5.6-22.4 parts of aluminum alloy processing waste metal chips, 23.7-48.5 parts of dye industry acidified copper slag, 37.3-60.6 parts of hematite tailings, 27.6-44.7 parts of iron mud, 17.4-48.9 parts of lime fluoride gypsum, 20.0-42.5 parts of electrolytic manganese plant tailings, and 0.8-28.6 parts of agricultural solid waste; S2. Placing the briquette in a reactor under a flowing atmosphere, wherein the flowing atmosphere is a mixture of nitrogen, oxygen, and argon; igniting the briquette to cause a self-propagating reaction to generate tin liquid; under the action of the high temperature and high pressure generated by the self-propagating reaction and the flowing atmosphere, the tin liquid escapes from the reactor and undergoes oxidation; the composition of the mixed gas, by volume, is 79.2-96.2 parts nitrogen, 4.1-21.3 parts oxygen, and 0.9-1.1 parts argon; and the flow rate of the mixed gas is 200-1000 mL / min; S3. Collecting the products generated by oxidation of the tin liquid to obtain oxygen vacancy nano-tin oxide; the nano-tin oxide has a purity of 84.94%-99.9%, a grain size of 12.14-75.67 nm, and an oxygen vacancy content of 24.36%-36.77%.

2. The method according to claim 1, characterized in that In step S1, the agricultural solid waste includes dead branches and leaves and / or straw.

3. The method according to claim 1, wherein In step S1, the tar pitch includes wood tar and asphalt, the amount of wood tar added to the mixture is 350-550 mL / kg, and the amount of asphalt added to the mixture is 0-150 mL / kg.

4. The method according to claim 1, wherein In step S1, the compact is pressed at a pressure of 2-10 MPa and for a time of 60-120 s; the compact is a cylindrical block with a height-to-diameter ratio of 1:2-1:

6.

5. The method according to claim 1, characterized in that In step S2, the volumetric rate of the briquettes in the reactor is 0.36-1.6 kg / L.

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