Method and device for synthesizing oxygen vacancy nano tin oxide by using waste raw materials

Abstract

The invention provides a method and a device for synthesizing oxygen vacancy nano tin oxide from waste raw materials, and the method takes industrial and agricultural wastes as raw materials, and realizes preparation of oxygen vacancy nano tin oxide through a self-propagating high-temperature synthesis technology and regulation and control of a flowing mixed atmosphere with an oxidation function. The prepared nano tin oxide product has the advantages of high purity, good dispersity, adjustable oxygen vacancy content, good photocatalytic performance and the like. According to the method and the device provided by the invention, while the oxygen vacancy content adjustable nano tin oxide preparation method is provided, the production energy consumption and the raw material cost of the existing oxygen vacancy nano tin oxide are reduced, the production efficiency is improved, the safe consumption of wastes is completed, the environmental protection pressure is greatly reduced, and the method and the device have relatively good economic and environmental benefits and are suitable for industrial production. Wide popularization and application prospects are realized.

Description

Technical Field

[0001] The 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. Nano-tin oxide has shown broad application prospects in transparent electrodes, gas sensors, lithium-ion batteries, and photoelectrocatalysis due to its unique optoelectronic properties, gas sensitivity, and chemical stability. Oxygen vacancies are the main type of defects 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, precise control of the oxygen vacancy content of nano-tin oxide materials is particularly important for improving their performance.

[0003] There are many literature reports on the preparation methods of nano-tin oxide, such as the hydrothermal synthesis method proposed in the patent application with patent document number CN1528671A; the microemulsion synthesis method proposed by Pan Qingyi et al. (Journal of Inorganic Materials, 1999, 14: 83-88); the sol-gel synthesis method and template synthesis method mentioned in patent document number CN106629822B. These preparation methods have the disadvantages of complex process flow and high requirements for equipment and operation. In order to solve these problems, existing research has applied the self-propagating high-temperature synthesis technology with advantages such as fewer steps, short process flow, simple process and high product quality to the preparation of nano-tin oxide. For example, the patent with patent document number CN101671050A discloses a method for preparing nano-tin oxide materials by using exothermic reaction; Xu Bingshe et al. (Metallic Materials and Engineering, 2007, S2: 492-495) prepared tin oxide nanowires by 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] At present, there have been many studies on methods for creating oxygen vacancies in nano-tin 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 nano-tin 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 regulate the oxygen vacancy content in the nano-tin oxide product. There are existing processes that can achieve material oxygen vacancy regulation, such as the electrochemical method mentioned in patent CN112939053A, which can control the oxygen vacancy concentration in the oxide by adjusting the composition of the electrolyte; patent CN113526567A discloses a method for preparing oxygen vacancy metal oxides by acid etching effect; patent CN106564892A obtains transition metal oxides with different reduction degrees by controlling the concentration, freeze drying time, and microwave combustion treatment time. These methods generally face problems such as complex production process, high energy consumption, and harsh operating conditions.

[0005] Based on the above reasons, a self-propagating high-temperature synthesis method of nano-tin oxide using industrial and agricultural waste as raw materials and capable of regulating the oxygen vacancy content of the product is provided. While preparing nano-tin oxide with low energy consumption and low cost, it can achieve rapid disposal of industrial and agricultural waste, which 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 method for synthesizing nano-tin oxide with adjustable oxygen vacancy content using solid waste as raw materials at low cost and low energy consumption.

[0007] The 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 purposes is to provide a method for synthesizing oxygen vacancy nano-tin oxide using waste raw materials, comprising the following steps: S1, mixing tin source waste with solid waste, grinding and drying to obtain a mixture; adding tar pitch to the mixture and mixing evenly, and then pressing into a briquette; 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 alone through self-propagating reactions, and agricultural solid waste that can assist the system in releasing heat and generate a certain amount of gas; S2, placing the green block in a reactor under a flowing atmosphere, wherein the flowing atmosphere is a mixed gas composed of nitrogen, oxygen and argon; igniting the green block 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 is oxidized; S3. Collect the products generated by oxidation of the tin liquid to obtain oxygen vacancy nano-tin oxide.

[0009] The general idea of ​​the present invention is as follows: The 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.

[0010] In the above method, the types of solid waste need to be screened first. The present invention uses industrial solid waste of specific composition, among which industrial solid waste that contains or can generate oxides or sulfides corresponding to aluminum, silicon, iron, manganese, and calcium through self-propagating reaction can form partially molten and mutually adjacent porous composite scum in the reaction, providing a certain pressure and channel for tin to disperse and escape from the reactor; industrial solid waste that contains or can generate metal elements or alloys with a density greater than that of tin through self-propagating reaction can form an alloy melt with a density much greater than that of tin in the reaction, so as to quickly settle below the tin liquid, and together with the scum above the tin liquid, form a closed micro-area, providing sufficient injection pressure for the escape of tin.

[0011] In the self-propagating reaction process, the elemental tin in the form of tin liquid is ejected under pressure at a local instantaneous high temperature and is entrained by the generated carbon dioxide, water vapor and other gases to escape the reactor, and is oxidized and non-equilibrium solidified under the flowing atmosphere of a mixed gas of nitrogen, oxygen and argon. Furthermore, by adjusting the composition and flow rate of the mixed gas, the degree of oxidation of tin, oxidation and cooling time can be controlled, thereby achieving the regulation of oxygen vacancies in the obtained product. Finally, the solidified tin oxide product will be transferred with the airflow, and it will be collected to obtain the target product.

[0012] Furthermore, in step S1, the industrial solid waste includes: a combination of one or more of aluminum alloy processing waste metal scraps, dye industry acidified copper slag, hematite tailings, iron mud, lime fluoride gypsum, and electrolytic manganese plant tailings. Among them, the main component of aluminum alloy processing waste metal scraps is Al, the main component of dye industry acidified copper slag is CuO and CuSO4·5H2O; the main component of hematite tailings is Fe2O3; the main component of iron mud is Fe3O4, Fe2O3, FeO and Fe; the main component of lime fluoride gypsum is CaSO4 and crystal water; the main component of electrolytic manganese plant tailings is MnO2, MnSO4, CaSO4, SiO2.

[0013] 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.

[0014] 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, compared with industrial products with similar components such as graphite and carbon powder, agricultural solid waste burns slowly, 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 covered with air, which is easier to burn than chemical reagents with the same composition.

[0015] 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 to form droplets as small as possible.

[0016] Preferably, in step S1, the mixture is composed of the following raw materials 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.

[0017] Preferably, in step S1, the industrial solid waste is ground and then 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 then passed through a 10-50 mesh sieve so that its particle size is not greater than 2 mm.

[0018] In the present invention, by optimizing and adjusting the ratio of each component in the raw material and the particle size distribution of the raw material, a balance is achieved between the released heat and the heat absorbed by the product, 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 mixing into the tin liquid to form impurities; in addition, suitable ratios and particle size distributions can achieve the regulation of the pressure in the reactor, while regulating the injection amount and injection speed of the tin liquid, avoiding excessive pressure that causes the alloy liquid below the tin liquid to be sprayed out and mixed into the tin liquid, thereby affecting the purity of the tin liquid.

[0019] Furthermore, 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. 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 blank making, but also can further increase the total heat release and gas production of the system through the combustion reaction.

[0020] The reaction types that may be involved in the method provided by the present invention are as follows: Al+M x O y →Al2O3+M (M is a metal element such as Cu, Fe, Mn, etc.) Al+CaSO4→CaAl2O4+CaS+SO2(g) Al+CaSO4→Al2O3+CaS+SO2(g) Al+MnSO4→Al2O3+MnS+SO2(g) Al+SnO→Al2O3+Sn CuSO4·5H2O→CuSO4+5H2O(g) CaSO4·2H2O→CaSO4·1 / 2H2O+3 / 2H2O(g) CaSO4·1 / 2H2O→CaSO4+1 / 2H2O(g) CuSO4→CuO+SO3(g) C x H y +O2→CO2(g)+H2O(g) C x H y O z +O2→CO2(g)+H2O(g) In addition, during the reaction, as the temperature changes, the system will undergo a series of complex phase change processes, including not only the physical state changes of raw materials, intermediates and reaction products, but also the eutectic reaction between metal oxides. Specifically, these phase change processes may include but are not limited to: Sn(s) Sn(l) Pb(s) Pb(l) Cu(s) Cu(l) Mn(s) Mn(l) SiO2-Al2O3·SiO2-Fe2O3·Al2O3(s) SiO2-Al2O3·SiO2(s)+L Al2O3-Al2O3·SiO2-Fe2O3·Al2O3(s) Al2O3-Al2O3·SiO2(s)+L Al2O3(s)+CaO(s)+SiO2(s) CaO·Al2O3·2SiO2(l) Fe(s) Fe(l) Fe2O3(s) Fe2O3(l) Al2O3(s)+SiO2(s) Al2O3·SiO2(l) Al2O3(s)+CaO(s) CaO·6Al2O3(l) Al2O3(s) Al2O3(l) CaO(s)+SiO2(s) 2CaO·SiO2(l) CaO(s) CaO(l) In the above reaction formula, L represents the mixed liquid phase of the product.

[0021] In different reaction stages or thermal environments of the present invention, the solid waste raw materials and the simple tin generated by the reaction exist in the form of tin liquid. Due to the action of gravity and the density stratification effect, the tin liquid gathers in the middle layer of the reaction pool and is covered by the porous scum composed of metal oxides and aluminosilicate eutectic solid solutions with lower density. At the same time, it is located above the alloy liquid composed of metals such as iron, copper, manganese, and lead with higher density. It is pressurized and ejected under local instantaneous high temperature and is entrained by the generated carbon dioxide, water vapor and other gases to escape from the reactor. Once the simple tin leaves the reactor, it is oxidized and non-equilibrium solidified in the flowing atmosphere formed by the mixed gas.

[0022] Furthermore, the composition of the atmosphere in the chamber and the gas extraction flow rate can be controlled in advance to control the degree of oxidation of tin, oxidation and cooling time, thereby achieving regulation of oxygen vacancies in the product. Finally, the solidified tin oxide product will be transferred with the airflow and captured by the collection device, thus completing the collection of the product.

[0023] Furthermore, in step S1, the compact is pressed at a pressure of 2-10 MPa and for a time of 60-120 s. Preferably, the compact is a cylindrical block with a height-to-diameter ratio in the range of 1:2-1:6.

[0024] Furthermore, in step S2, the volumetric rate 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 volumetric rate are selected so that the raw material particles are adjacent to each other, the combustion wave after ignition is not easily extinguished in the process of self-propagating transmission, and sufficient pores are left between the raw material particles and around the briquette so that aerobic combustion can be fully carried out.

[0025] Furthermore, in step S2, the composition of the flowing atmosphere and the flow rate of the mixed gas that match the injection amount and injection speed of the tin liquid are selected, so as to control the dispersion, concentration and ambient air pressure, oxygen content and residence time of the tin liquid in the air in the cabin, adjust the oxidation degree, oxidation and cooling time of the tin, and thus realize the regulation of the oxygen vacancies of the obtained product. Preferably, the composition of the mixed gas is 79.2-96.2 parts by volume of nitrogen, 4.1-21.3 parts of oxygen, and 0.9-1.1 parts of argon; the flow rate of the mixed gas is 200-1000 mL / min.

[0026] The method for synthesizing oxygen vacancy nano-tin oxide using solid waste raw materials provided by the present invention fully utilizes the advantages of self-propagating high-temperature synthesis technology, and realizes the regulation of the oxygen vacancy content of the product without introducing any template or harsh conditions through the nano-tin oxide preparation system and process design. In addition, the method significantly reduces the cost of raw materials for preparing nano-tin oxide and realizes the large-scale disposal of industrial and agricultural waste.

[0027] 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 vacancies are 24.36%-36.77%.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] A reactor is provided at the center of the bottom of the reaction chamber. The reactor is used to accommodate raw material blocks and provide a place for self-propagating reaction. A pressure detector and a laser igniter are provided above the reactor. The pressure detector is used to detect the pressure change 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 to trigger a self-propagating reaction. The electrostatic precipitator is used to capture the solidified tin oxide products transferred with the airflow. A collection box for collecting products is provided below the electrostatic precipitator, and an exhaust pipe is provided at the end of the collection box.

[0032] Compared with the prior art, the present invention has the following beneficial effects: (1) The method for synthesizing oxygen vacancy nano-tin oxide using solid waste raw materials provided by the present invention 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. The method can achieve directional control of the oxygen vacancy content of the nano-tin oxide product by adjusting the process parameters such as the raw material system, the composition of the mixed atmosphere and the atmosphere flow rate. The process is simple, the energy consumption is low, and it is green and environmentally friendly.

[0033] (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%.

[0034] (3) The method and device for synthesizing oxygen vacancy nano-tin oxide using solid waste raw materials provided by the present invention can obtain nano-tin oxide products with good performance by using industrial and agricultural waste as raw materials, which not only significantly reduces the raw material cost of preparing nano-tin oxide, but also realizes the safe disposal of waste. For every 1 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

[0035] 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; Figure 2 This is the XRD pattern of the oxygen vacancy nano-tin oxide sample prepared in Example 1 of the present invention; Figure 3 This is a Raman graph of the oxygen vacancy nano-tin oxide sample prepared in Example 2 of the present invention; 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

[0036] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0037] 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.

[0038] The present invention provides a method for synthesizing oxygen vacancy nano-tin oxide using waste raw materials. The structure of the device used in the method is shown in FIG. 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.

[0039] 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 transmission pipe 2, and a mixed gas with a specific proportion is obtained by controlling the gas partial pressure; the mixed gas is introduced 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.

[0040] A reactor 7 is provided at the center of the bottom of the reaction chamber. The reactor is used to accommodate 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 change 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 to trigger a self-propagating reaction. The electrostatic precipitator 11 is used to capture the solidified tin oxide product transferred with the air flow. A collection box 10 for collecting the product is provided below the electrostatic precipitator, and an exhaust pipe 12 is provided at the end thereof.

[0041] The present invention is further described below in conjunction with specific examples. Examples 1-5 show that the present invention analyzes the composition, output, and storage and transportation costs of typical waste containing target components, combines a large number of experimental studies, thermodynamic calculations, and kinetic modeling to ultimately determine the existing raw material system composition scheme and oxygen vacancy nano-tin oxide preparation process parameter combination, which is only used as an example and is not intended to be a limitation of the present invention.

[0042] The main raw materials and parameters involved in each embodiment of the present invention are shown in Table 1 and Table 2 below.

[0043] Table 1

[0044] 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 0.075 mm, and agricultural solid waste corn stalks are ground and passed through a 10-50 mesh sieve to make their particle size no more than 2 mm.

[0045] Table 2

[0046] Example 1 This embodiment provides a method for synthesizing oxygen vacancy nano-tin oxide using waste raw materials, comprising the following steps: Step 1: passing aluminum alloy processing waste metal chips, dye industry acidified copper slag, hematite tailings, iron mud, lime fluoride gypsum, electrolytic manganese plant tailings, and processing waste tin through a 200-mesh sieve to make the particle size not exceed 0.075 mm, passing corn stalks through a 30-mesh sieve to make the particle size not exceed 0.6 mm, and after drying, weighing 1 kg of solid waste raw materials according to a mass ratio of 22.4:48.5:60.6:44.7:48.9:42.5:45.9:0.8, adding 350 mL of wood tar and 150 mL of asphalt, and mixing them evenly, pressing at a pressure of 10 MPa and holding the pressure for 60 seconds to obtain a raw material block 8 with a height-to-diameter ratio of 1:2; Step 2: After placing the green block obtained in step 1 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 in a volume ratio of 82.8:16.7:1.1 is added in the atmosphere mixing device 3, and the extraction flow rate is controlled to be 200 mL / min. When the air pressure in the reaction chamber reaches a preset value, a laser igniter 6 is used to ignite the green block to cause a reaction; Step 3, after the reaction is finished, the products are collected centrally by means of an electrostatic dust removal device 11 , and oxygen vacancy nano-tin oxide products are obtained in a collection box 10 .

[0047] 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; 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.

[0048] Example 2 This embodiment provides a method for synthesizing oxygen vacancy nano-tin oxide using waste raw materials, comprising the following steps: Step 1: passing aluminum alloy processing waste metal chips, dye industry acidified copper slag, hematite tailings, iron mud, lime fluoride gypsum, electrolytic manganese plant tailings, and processing waste tin through a 250-mesh sieve to make the particle size not exceed 0.065 mm, passing corn stalks through a 10-mesh sieve to make the particle size not exceed 2 mm, and after drying, weighing 1 kg of solid waste raw materials according to a mass ratio of 5.6:23.7:37.3:27.6:17.4:20:24:16.7, adding 375 mL of wood tar and 75 mL of asphalt, and mixing them evenly, pressing at a pressure of 6 MPa and holding the pressure for 90 seconds to obtain a raw material block 8 with a height-to-diameter ratio of 1:4; Step 2: After placing the green block obtained in step 1 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 in a volume ratio of 90:10.3:1 is added in the atmosphere mixing device 3, and the extraction flow rate is controlled to be 500 mL / min. When the air pressure in the reaction chamber reaches a preset value, a laser igniter 6 is used to ignite the green block to cause a reaction; Step 3: After the reaction is completed, the products are collected centrally by means of an electrostatic dust removal device 11 , and oxygen vacancy nano-tin oxide products are obtained in a collection box 10 .

[0049] 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.

[0050] Example 3 This embodiment provides a method for synthesizing oxygen vacancy nano-tin oxide using waste raw materials, comprising the following steps: Step 1: passing aluminum alloy processing waste metal chips, dye industry acidified copper slag, hematite tailings, iron mud, lime fluoride gypsum, electrolytic manganese plant tailings, and processing waste tin through a 250-mesh sieve to make the particle size not exceed 0.065 mm, passing corn stalks through a 10-mesh sieve to make the particle size not exceed 2 mm, and after drying, weighing 1 kg of solid waste raw materials according to a mass ratio of 7.8:31.6:40.5:35:30:20:13.5:16.7, adding 375 mL of wood tar and 75 mL of asphalt, and mixing them evenly, pressing at a pressure of 6 MPa and holding the pressure for 90 seconds to obtain a raw material block 8 with a height-to-diameter ratio of 1:4; Step 2: After placing the green block obtained in step 1 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 in a volume ratio of 90:10.3:1 is added in the atmosphere mixing device 3, and the extraction flow rate is controlled to be 500 mL / min. When the air pressure in the reaction chamber reaches a preset value, a laser igniter 6 is used to ignite the green block to cause a reaction; Step 3: After the reaction is completed, the products are collected centrally by means of an electrostatic dust removal device 11 , and oxygen vacancy nano-tin oxide products are obtained in a collection box 10 .

[0051] 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.

[0052] Example 4 This embodiment provides a method for synthesizing oxygen vacancy nano-tin oxide using waste raw materials, comprising the following steps: Step 1: passing aluminum alloy processing waste metal chips, dye industry acidified copper slag, hematite tailings, iron mud, lime fluoride gypsum, electrolytic manganese plant tailings, and processing waste tin through a 250-mesh sieve to make the particle size not exceed 0.065 mm, passing corn stalks through a 10-mesh sieve and drying them to make the particle size not exceed 2 mm, weighing 1 kg of solid waste raw materials according to a mass ratio of 5.6:23.7:37.3:27.6:17.4:20:24:16.7, adding 375 mL of wood tar and 75 mL of asphalt, and mixing them evenly, pressing at a pressure of 6 MPa and holding the pressure for 90 seconds to obtain a raw material block 8 with a height-to-diameter ratio of 1:4; Step 2: After placing the green block obtained in step 1 at 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 in a volume ratio of 96.2:4.1:0.9 is added in the atmosphere mixing device 3, and the extraction flow rate is controlled to be 800 mL / min. When the air pressure in the reaction chamber reaches a preset value, a laser igniter 6 is used to ignite the green block to cause a reaction; 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 .

[0053] 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.

[0054] Example 5 This embodiment provides a method for synthesizing oxygen vacancy nano-tin oxide using waste raw materials, comprising the following steps: Step 1: passing aluminum alloy processing waste metal chips, dye industry acidified copper slag, hematite tailings, iron mud, lime fluoride gypsum, electrolytic manganese plant tailings, and processing waste tin through a 300-mesh sieve to make the particle size not exceed 0.055 mm, and corn stalks through a 50-mesh sieve and dried to make the particle size not exceed 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 is added, and the mixture is evenly mixed. The raw material block 8 with a height-to-diameter ratio of 1:6 is obtained under a pressure of 2 MPa and a pressure holding time of 120 s. Step 2: After placing the green block obtained in step 1 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 in a volume ratio of 79.2:21.3:1 is added in the atmosphere mixing device 3, and the extraction flow rate is controlled to be 1000 mL / min. When the air pressure in the reaction chamber reaches a preset value, a laser igniter 6 is used to ignite the green block to cause a reaction; 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 .

[0055] 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.

[0056] The above are only preferred embodiments of the present invention, and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the contents of the specification of the present invention 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 to obtain a mixture; adding tar pitch to the mixture and mixing evenly, and then pressing into a briquette; 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 alone through self-propagating reactions, and agricultural solid waste that can assist the system in releasing heat and generate a certain amount of gas; S2, placing the green block in a reactor under a flowing atmosphere, wherein the flowing atmosphere is a mixed gas composed of nitrogen, oxygen and argon; igniting the green block 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 is oxidized; S3. Collect the products generated by oxidation of the tin liquid to obtain oxygen vacancy nano-tin oxide.

2. The method according to claim 1, characterized in that In step S1, the industrial solid waste includes: a combination of one or more of aluminum alloy processing waste metal chips, dye industry acidified copper slag, hematite tailings, iron mud, lime fluorite, and electrolytic manganese plant tailings slag; the tin source waste includes a combination of one or more of processing waste tin, solder paste, solder waste, and tin plating waste.

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

4. The method according to claim 1, characterized in that: In step S1, the mixture is composed of the following raw materials 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.

5. The method according to claim 1, characterized in that 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.

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

6.

7. The method according to claim 1, characterized in that In step S2, the volume ratio of the blocks in the reactor is 0.36-1.6 kg / L.

8. The method according to claim 1, characterized in that In step S2, the composition of the mixed gas is, by volume, 79.2-96.2 parts of nitrogen, 4.1-21.3 parts of oxygen, and 0.9-1.1 parts of argon; the flow rate of the mixed gas is 200-1000 mL / min.

9. The nano-tin oxide prepared by the method according to any one of claims 1 to 8, characterized in that: The purity of the nano-tin oxide is 84.94%-99.9%, the grain size is 12.14-75.67nm, and the oxygen vacancy content is 24.36%-36.77%.

10. A device for synthesizing oxygen vacancy nano-tin oxide using waste raw materials based on the method according to any one of claims 1 to 8, characterized in that: include: A gas storage source (1), a gas transmission pipe (2), an atmosphere mixing device (3), a reaction chamber (4), a flow rate control device (9) and an electrostatic dust removal device (11) connected in sequence; A reactor (7) for placing the briquettes is provided at the bottom center of the reaction chamber (4), and a gas pressure detector (5) and a laser igniter (6) are provided above the reactor (7); A collection box (10) is provided below the electrostatic precipitator (11), and the end of the electrostatic precipitator (11) is connected to an exhaust pipe (12).

Images