Preparation method and application of FexOy / TiO2 / C composite microwave absorbing material

Abstract

The invention discloses a preparation method and application of a FexOy / TiO2 / C composite microwave absorbing material, belongs to the technical field of solid waste recycling and microwave absorbing materials, solves the technical problem of resource utilization of waste powdered ink and waste warm paste residues, and adopts the technical scheme that firstly, the waste powdered ink and the waste warm paste residues are subjected to crushing, ball milling, screening and drying treatment; secondly, deionized water is added into a mixed solution composed of tetrabutyl titanate, glacial acetic acid and absolute ethyl alcohol, sol is obtained, solid waste powder is added into the sol, magnetic stirring and uniform mixing are conducted, and gel is obtained after aging; and finally, drying the gel, and roasting at a constant temperature in an N2 atmosphere to prepare the FexOy / TiO2 / C composite microwave absorbing material. The composite wave-absorbing material is prepared by taking the waste powdered ink, the waste warm paste residues and the tetrabutyl titanate as main raw materials, a new thought is provided for comprehensive utilization of solid wastes, and low-cost preparation of the microwave-absorbing material is also realized.

Description

Technical Field

[0001] The invention belongs to the technical field of solid waste recycling and microwave absorbing materials, and specifically relates to a Fe x O y Preparation method and application of / TiO2 / C composite microwave absorbing material. Background Art

[0002] The rapid development of electronic communication technology has led to more and more electromagnetic waves appearing in people's daily lives. The electromagnetic radiation caused by this not only affects human health, but also becomes another major source of pollution after air pollution and water pollution. Microwave absorbing materials can use their own mechanisms to attenuate incident electromagnetic waves and convert electromagnetic energy into heat energy or other forms of energy to dissipate it. They can effectively solve the problem of electromagnetic radiation, so they have received widespread attention from researchers. At the same time, with the widespread application of microwave absorbing materials in practice, they not only need to meet the requirements of "thin", "light", "wide" and "strong", but also need to take into account low cost and other requirements, so as to expand their practical application areas.

[0003] With the continuous development of science and technology, office conditions are further automated, and the application of modern office equipment such as laser printers and copiers has increased dramatically around the world. The output of waste toner has also increased accordingly. Every year, 60% to 80% of waste toner is discharged without treatment. However, since waste toner contains a variety of new pollutants such as micro-nano plastics, nano-oxides, and nano-carbon, there are potential ecological and human health risks. Therefore, scientific disposal of waste toner is an urgent task for achieving green development. The rich carbon-based and metal nanoparticles in waste toner give it excellent electrical, mechanical, adsorption and catalytic properties. Related research has been conducted in the fields of electrode materials, photocatalysts, adsorbents and concrete modification. However, there are still problems such as complex preparation process, long cycle, and low utilization rate. Therefore, it is urgent to further improve the recycling and resource utilization rate of waste toner.

[0004] A heating pad is a heating product composed of a raw material layer, a gelatin layer, and a non-woven fabric. Its reaction principle is that iron oxidation occurs under the action of oxygen in the air to release heat. The raw material layer of the heating pad is an important source of heat release. Its main components are iron powder, activated carbon, vermiculite, resin, inorganic salts, water, etc. Due to different manufacturers, the content of iron powder also varies, and the basic content is between 68% and 85%. As a portable and effective heating product, heating pads have been widely used. Due to their low price, most of them are directly treated as ordinary garbage after use, which has caused certain pollution to the environment and also caused waste of resources. Recycling and reusing discarded heating pads not only reduces pollution to the environment, but also realizes the resource reuse of the effective components therein, alleviating the problem of resource shortage.

[0005] In recent years, titanium dioxide (TiO2) has attracted widespread attention from researchers due to its good thermal stability and chemical corrosion resistance, non-toxicity, simple synthesis process and low synthesis cost. It has been widely used in photoelectric catalysis, coatings, sensors, semiconductors, papermaking industry, solar cells and lithium batteries. In addition, titanium dioxide also has certain dielectric loss properties and is a typical dielectric material that can be used in the field of absorbing materials. However, single titanium dioxide cannot achieve good impedance matching and it is difficult to obtain good microwave absorption performance. Magnetic powder has a high magnetic permeability. Compounding titanium dioxide with magnetic components can increase the magnetic loss of electromagnetic waves, enrich the electromagnetic wave loss mechanism, achieve impedance matching of composite materials, and improve absorbing performance.

[0006] In summary, if we can reasonably develop and utilize waste toner or waste heating pad residue to prepare Fe x O y / TiO2 / C composite microwave absorbing materials can not only effectively alleviate the ecological environmental pressure caused by the discharge of waste toner or waste heating pad residues, but also reduce the production cost of composite absorbing materials, realize the transformation of solid waste into high value-added products, and improve the recycling level of solid waste resources. Summary of the invention

[0007] The main purpose of the present invention is to overcome the shortcomings of the prior art and solve the problem of resource utilization of waste toner and waste heating pads. The present invention provides a Fe x O y The preparation method and application of / TiO2 / C composite microwave absorbing material provide new ideas for the high value-added and large-scale application of waste toner and waste heating pads, and at the same time realize the low-cost preparation of composite microwave absorbing materials.

[0008] In order to achieve the above-mentioned purpose of the invention, the technical solution adopted by the present invention is: Fe x O y The preparation method of the / TiO2 / C composite microwave absorbing material comprises the following steps: S1. After crushing and ball-milling the solid waste, the solid waste is sieved through a 100-300 mesh standard sieve, and the sieved solid waste powder is placed in an oven for drying at a temperature of 60° C. to 100° C. for a drying time of 4 to 8 hours, and is reserved for use in a subsequent step; the solid waste is waste toner or waste heating pad residue; S2. First, tetrabutyl titanate, glacial acetic acid, and anhydrous ethanol are mixed uniformly in a volume ratio of (2-8.5):(0-4):(4-12) to obtain a mixed solution; secondly, deionized water is added to the mixed solution, and the volume of the deionized water accounts for 1%-9% of the total volume of the mixed solution to obtain a sol; thirdly, the solid waste powder dried in step S1 is weighed and added to the sol, and the mass ratio of the solid waste powder to the tetrabutyl titanate in the sol is (1-2):(1-10), and the mixture is mixed uniformly by magnetic stirring; finally, a gel is obtained after aging; S3. First, the gel prepared in step S2 is placed in an oven for drying at a temperature of 60°C to 100°C for 8 to 12 hours to obtain a precursor dry gel; then, the precursor dry gel is placed in a tubular furnace and calcined at a constant temperature in a N2 atmosphere at a temperature of 400°C to 1000°C for 2 hours, and then cooled to room temperature with the furnace to obtain Fe x O y / TiO2 / C composite microwave absorbing material.

[0009] Furthermore, the chemical composition and mass percentage of the waste toner are: Fe2O3: 55.79%, SiO2: 17.32%, ZnO: 6.95%, C: 10.81%, CuO: 5.72%, CaO: 3.41%; the composition and mass percentage of the waste heating pad residue are: Fe2O3: 63.3%, C: 22.2%, SiO2: 8.6%, Al2O3: 3.5%, CaO: 2.4%.

[0010] The Fe prepared by the above-mentioned preparation method x O y Application of / TiO2 / C composite microwave absorbing materials in microwave absorption process.

[0011] Furthermore, the Fe x O y The effective phase for microwave absorption in the / TiO2 / C composite microwave absorbing material is Fe x O y , TiO2 and C, the Fe x O y is Fe or Fe3O4; among which, Fe x O y As magnetic components, TiO2 and C serve as dielectric components.

[0012] Further, in the Fe x O y In the / TiO2 / C composite microwave absorbing material, the dielectric component TiO2 is wrapped around the magnetic component Fe x O yOutside the composite absorbing material, the dielectric component C is evenly distributed in the composite absorbing material.

[0013] The beneficial effects of the present invention are: 1. The main raw materials used in the present invention are waste toner or waste heating pad residue, which are effectively recycled to prepare Fe x O y / BaTiO3 / C composite microwave absorbing material, the preparation process is simple, which helps to achieve low-cost preparation of microwave absorbing materials; 2. During the calcination process in N2 atmosphere, Fe2O3 and C in the waste toner or waste heating pad residue undergo carbothermal reduction reaction to obtain Fe3O4 or Fe, without the need to add additional carbon source; the generated Fe3O4 or Fe acts as a magnetic component, and TiO2 and C act as dielectric components. The magnetic component and the dielectric component work together to optimize the microwave absorption performance of the composite material; 3. The present invention adopts TiO2 as the dielectric component. On the one hand, it can adjust the excessively high dielectric constant of the carbon material, provide dielectric loss together with carbon, and synergistically enhance the microwave absorption performance of the material; on the other hand, TiO2 has excellent thermal stability, and coating TiO2 on the surface of the magnetic component can improve the thermal stability of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The microwave reflection loss curve of the Fe3O4 / TiO2 / C composite microwave absorbing material prepared using waste toner as raw material in Example 1; Figure 2 The Raman spectrum of the Fe / TiO2 / C composite microwave absorbing material prepared using waste toner as raw material in Example 2; Figure 3 The Raman spectrum of the Fe / TiO2 / C composite microwave absorbing material TiO2 prepared using waste toner as raw material in Example 3; Figure 4 This is the X-ray diffraction spectrum of the Fe / TiO2 / C composite microwave absorbing material prepared using waste toner as raw material in Example 4.

[0015] Figure 5 The microwave reflection loss curve of the Fe / TiO2 / C composite microwave absorbing material prepared using the waste heating pad residue as raw material in Example 5; Figure 6 The XRD spectrum of the Fe3O4 / TiO2 / C composite microwave absorbing material prepared using the waste heating pad residue as raw material in Example 6; Figure 7 This is the Raman spectrum of the Fe / TiO2 / C composite microwave absorbing material prepared using the residue of discarded heating pads as raw materials in Example 7. DETAILED DESCRIPTION

[0016] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. Example 1

[0017] The preparation method of Fe3O4 / TiO2 / C composite microwave absorbing material comprises the following steps: S1. Weigh the waste toner and sieve it through a 120-mesh standard sieve. The sieved waste toner is placed in an oven for drying at a temperature of 80°C for 6 hours, and is reserved for later use. The chemical composition and mass percentage of the waste toner are: Fe2O3: 55.79%, SiO2: 17.32%, ZnO: 6.95%, C: 10.81%, CuO: 5.72%, CaO: 3.41%; S2. First, tetrabutyl titanate, glacial acetic acid, and anhydrous ethanol are mixed uniformly in a volume ratio of 8.5:2:10 to obtain a mixed solution; secondly, 0.45 mL of deionized water is added to the mixed solution to obtain a sol; thirdly, the waste toner dried in step S1 is weighed and added to the sol, the mass ratio of the waste toner to the tetrabutyl titanate in the sol is 1:1, and the mixture is uniformly mixed by magnetic stirring; finally, a gel is obtained after aging; S3. First, the gel prepared in step S2 is placed in an oven for drying at a temperature of 80°C for 12 hours to obtain a precursor dry gel; then, the precursor dry gel is placed in a tubular furnace and calcined at a constant temperature in a N2 atmosphere at a temperature of 600°C for 2 hours, and then cooled to room temperature with the furnace to obtain a Fe3O4 / TiO2 / C composite microwave absorbing material.

[0018] The Fe3O4 / TiO2 / C composite microwave absorbing material prepared by the preparation method described in Example 1 is used in the microwave absorption process, and the effective phases for microwave absorption are Fe3O4, TiO2 and C, wherein Fe3O4 is used as a magnetic component, and TiO2 and C are used as dielectric components; and the dielectric component TiO2 is wrapped around the outside of the magnetic component Fe3O4, and the dielectric component C is uniformly distributed in the composite absorbing material.

[0019] like Figure 1 As shown, when the Fe3O4 / TiO2 / C composite microwave absorbing material prepared in Example 1 is used in the microwave absorption process, when the coating thickness is 1.5 mm, its effective bandwidth is 5.0 GHz and the minimum reflection loss value is -25.2 dB. Example 2

[0020] The preparation method of Fe / TiO2 / C composite microwave absorbing material comprises the following steps: S1. Weigh the waste toner and sieve it through a 140-mesh standard sieve. The sieved waste toner is placed in an oven and dried at a drying temperature of 80°C for 6 hours, and is reserved for use in the next step. The chemical composition and mass percentage of the waste toner are: Fe2O3: 55.79%, SiO2: 17.32%, ZnO: 6.95%, C: 10.81%, CuO: 5.72%, CaO: 3.41%; S2. First, tetrabutyl titanate, glacial acetic acid, and anhydrous ethanol are mixed uniformly in a volume ratio of 8.5:2:10 to obtain a mixed solution; secondly, 0.45 mL of deionized water is added to the mixed solution to obtain a sol; thirdly, the waste toner dried in step S1 is weighed and added to the sol, the mass ratio of the waste toner to the tetrabutyl titanate in the sol is 1:2, and the mixture is mixed uniformly by magnetic stirring; finally, a gel is obtained after aging; S3. First, the gel prepared in step S2 is placed in an oven for drying at a temperature of 80°C for 10 hours to obtain a precursor dry gel; then, the precursor dry gel is placed in a tubular furnace and calcined at a constant temperature in a N2 atmosphere at a temperature of 700°C for 2 hours, and then cooled to room temperature with the furnace to obtain a Fe / TiO2 / C composite microwave absorbing material.

[0021] The Fe / TiO2 / C composite microwave absorbing material prepared by the preparation method described in Example 2 is used in the microwave absorption process, and the effective phases for microwave absorption are Fe, TiO2 and C, wherein Fe is used as a magnetic component, and TiO2 and C are used as dielectric components; and the dielectric component TiO2 is wrapped around the outside of the magnetic component Fe, and the dielectric component C is uniformly distributed in the composite absorbing material.

[0022] like Figure 2 As shown, the Raman spectrum of the Fe / TiO2 / C composite microwave absorbing material prepared in Example 2 has D peak and G peak, which proves that after the carbothermal reduction reaction, there is still excess carbon inside the Fe / TiO2 / C composite material. Example 3

[0023] The preparation method of Fe / TiO2 / C composite microwave absorbing material comprises the following steps: S1. Weigh the waste toner and sieve it through a 150-mesh standard sieve. The sieved waste toner is placed in an oven and dried at a drying temperature of 80°C for 6 hours, and is reserved for use in the next step. The chemical composition and mass percentage of the waste toner are: Fe2O3: 55.79%, SiO2: 17.32%, ZnO: 6.95%, C: 10.81%, CuO: 5.72%, CaO: 3.41%; S2. First, tetrabutyl titanate, glacial acetic acid, and anhydrous ethanol are mixed uniformly in a volume ratio of 6:3:8 to obtain a mixed solution; secondly, 0.45 mL of deionized water is added to the mixed solution to obtain a sol; thirdly, the waste toner dried in step S1 is weighed and added to the sol, the mass ratio of the waste toner to the tetrabutyl titanate in the sol is 1:3, and the mixture is mixed uniformly by magnetic stirring; finally, a gel is obtained after aging; S3. First, the gel prepared in step S2 is placed in an oven for drying at a temperature of 80°C for 8 hours to obtain a precursor dry gel; then, the precursor dry gel is placed in a tubular furnace and calcined at a constant temperature in a N2 atmosphere at a temperature of 700°C for 2 hours, and then cooled to room temperature with the furnace to obtain a Fe / TiO2 / C composite microwave absorbing material.

[0024] like Figure 3 As shown, the Raman spectrum of the Fe / TiO2 / C composite microwave absorbing material prepared in Example 3 has characteristic peaks of the TiO2 anatase phase, indicating that a TiO2 crystal phase with good crystallinity can be obtained through the sol-gel process. Example 4

[0025] The preparation method of Fe / TiO2 / C composite microwave absorbing material comprises the following steps: S1. Weigh the waste toner and sieve it through a 150-mesh standard sieve. The sieved waste toner is placed in an oven for drying at a temperature of 80°C for 6 hours, and is reserved for later use. The chemical composition and mass percentage of the waste toner are: Fe2O3: 55.79%, SiO2: 17.32%, ZnO: 6.95%, C: 10.81%, CuO: 5.72%, CaO: 3.41%; S2. First, tetrabutyl titanate, glacial acetic acid, and anhydrous ethanol are mixed uniformly in a volume ratio of 5:3:8 to obtain a mixed solution; secondly, 0.45 mL of deionized water is added to the mixed solution to obtain a sol; thirdly, the waste toner dried in step S1 is weighed and added to the sol, the mass ratio of the waste toner to tetrabutyl titanate in the sol is 1:3.5, and the mixture is uniformly mixed by magnetic stirring; finally, a gel is obtained after aging; S3. First, the gel prepared in step S2 is placed in an oven for drying at a temperature of 80°C for 12 hours to obtain a precursor dry gel; then, the precursor dry gel is placed in a tubular furnace and calcined at a constant temperature in a N2 atmosphere at a temperature of 800°C for 2 hours, and then cooled to room temperature with the furnace to obtain a Fe / TiO2 / C composite microwave absorbing material.

[0026] like Figure 4 As shown, the main phases of the Fe / TiO2 / C composite microwave absorbing material prepared in this Example 4 are Fe, TiO2 and C. Example 5

[0027] The preparation method of Fe / TiO2 / C composite microwave absorbing material comprises the following steps: S1. The waste heating pad residue is crushed, ball-milled and then sieved through a 150-mesh standard sieve. The sieved waste heating pad residue powder is placed in an oven and dried at a temperature of 80°C for 5 hours, and is reserved for use in the next step. The composition and mass percentage of the waste heating pad residue are: Fe2O3: 63.3%, C: 22.2%, SiO2: 8.6%, Al2O3: 3.5%, CaO: 2.4%; S2. First, tetrabutyl titanate, glacial acetic acid and anhydrous ethanol are mixed uniformly in a volume ratio of 3:1:5 to obtain a mixed solution; secondly, deionized water is added to the mixed solution, and the volume of the deionized water accounts for 3% of the total volume of the mixed solution to obtain a sol; thirdly, the waste heating pad residue powder after drying in step S1 is weighed and added to the sol, and the mass ratio of the waste heating pad residue powder to the tetrabutyl titanate in the sol is 1:6, and the mixture is mixed uniformly by magnetic stirring; finally, a gel is obtained after aging; S3. First, the gel prepared in step S2 is placed in an oven for drying at a temperature of 80°C for 10 hours to obtain a precursor dry gel; then, the precursor dry gel is placed in a tubular furnace and calcined at a constant temperature in a N2 atmosphere at a temperature of 1000°C for 2 hours, and then cooled to room temperature with the furnace to obtain a Fe / TiO2 / C composite microwave absorbing material.

[0028] The Fe / TiO2 / C composite microwave absorbing material prepared by the preparation method described in Example 5 is used in the microwave absorption process, and the effective phases for microwave absorption are Fe, TiO2 and C, wherein Fe is used as a magnetic component, TiO2 and C are used as dielectric components, and the dielectric component TiO2 is wrapped around the outside of the magnetic component Fe, and the dielectric component C is uniformly distributed in the composite absorbing material.

[0029] like Figure 5As shown, when the Fe / TiO2 / C composite microwave absorbing material prepared using the residue of discarded heating pads in Example 5 is used in the microwave absorption process, when the coating thickness is 5.0 mm, the minimum reflection loss is -38.6 GHz; when the coating thickness is 1.5 mm, its effective bandwidth can reach a maximum of 3.5 GHz. Example 6

[0030] The preparation method of Fe3O4 / TiO2 / C composite microwave absorbing material comprises the following steps: S1. The waste heating pad residue is crushed, ball-milled and then sieved through a 200-mesh standard sieve. The sieved waste heating pad residue powder is placed in an oven and dried at a drying temperature of 100°C for 5 hours, and is reserved for use in the next step. The composition and mass percentage of the waste heating pad residue are: Fe2O3: 63.3%, C: 22.2%, SiO2: 8.6%, Al2O3: 3.5%, CaO: 2.4%; S2. First, tetrabutyl titanate, glacial acetic acid and anhydrous ethanol are mixed in a volume ratio of 5:1:6 to obtain a mixed solution; secondly, deionized water is added to the mixed solution, and the volume of the deionized water accounts for 4% of the total volume of the mixed solution to obtain a sol; thirdly, the waste heating pad residue powder after drying in step S1 is weighed and added to the sol, and the mass ratio of the waste heating pad residue powder to the tetrabutyl titanate in the sol is 1:5, and the mixture is mixed evenly by magnetic stirring; finally, a gel is obtained after aging; S3. First, the gel prepared in step S2 is placed in an oven for drying at a drying temperature of 100°C for 10 hours to obtain a precursor dry gel; then, the precursor dry gel is placed in a tubular furnace and calcined at a constant temperature in a N2 atmosphere at a calcination temperature of 500°C for 2 hours, and then cooled to room temperature with the furnace to obtain a Fe3O4 / TiO2 / C composite microwave absorbing material.

[0031] The Fe3O4 / TiO2 / C composite microwave absorbing material prepared by the preparation method described in Example 6 is used in the microwave absorption process. The effective phases for microwave absorption are Fe3O4, TiO2 and C (such as Figure 6 As shown in the figure, Fe3O4 is used as a magnetic component, TiO2 and C are used as dielectric components, and the dielectric component TiO2 is wrapped around the outside of the magnetic component Fe3O4, and the dielectric component C is uniformly distributed in the composite absorbing material. Example 7

[0032] The preparation method of Fe / TiO2 / C composite microwave absorbing material comprises the following steps: S1. The waste heating pad residue is crushed, ball-milled and then sieved through a 200-mesh standard sieve. The sieved waste heating pad residue powder is placed in an oven and dried at a temperature of 80°C for 8 hours, and is reserved for use in the next step. The composition and mass percentage of the waste heating pad residue are: Fe2O3: 63.3%, C: 22.2%, SiO2: 8.6%, Al2O3: 3.5%, CaO: 2.4%; S2. First, tetrabutyl titanate, glacial acetic acid and anhydrous ethanol are mixed uniformly in a volume ratio of 3:1:4 to obtain a mixed solution; secondly, deionized water is added to the mixed solution, and the volume of the deionized water accounts for 8% of the total volume of the mixed solution to obtain a sol; thirdly, the waste heating pad residue powder after drying in step S1 is weighed and added to the sol, and the mass ratio of the waste heating pad residue powder to the tetrabutyl titanate in the sol is 1:8, and the mixture is mixed uniformly by magnetic stirring; finally, a gel is obtained after aging; S3. First, the gel prepared in step S2 is placed in an oven for drying at a temperature of 80°C for 10 hours to obtain a precursor dry gel; then, the precursor dry gel is placed in a tubular furnace and calcined at a constant temperature in a N2 atmosphere at a temperature of 800°C for 2 hours, and then cooled to room temperature with the furnace to obtain a Fe / TiO2 / C composite microwave absorbing material.

[0033] The Fe / TiO2 / C composite microwave absorbing material prepared by the preparation method described in Example 5 is used in the microwave absorption process, and the effective phases for microwave absorption are Fe, TiO2 and C, wherein Fe is used as a magnetic component, TiO2 and C are used as dielectric components, and the dielectric component TiO2 is wrapped around the outside of the magnetic component Fe, and the dielectric component C is uniformly distributed in the composite absorbing material.

[0034] like Figure 7 As shown, the Raman spectrum of the Fe / TiO2 / C composite microwave absorbing material prepared using discarded heating pads in Example 7 has characteristic peaks of the TiO2 rutile phase, proving that the sol-gel method can successfully prepare a TiO2 crystal phase with good crystallinity. Example 8

[0035] The preparation method of Fe3O4 / TiO2 / C composite microwave absorbing material comprises the following steps: S1. The waste heating pad residue is crushed, ball-milled and then sieved through a 200-mesh standard sieve. The sieved waste heating pad residue powder is placed in an oven and dried at a drying temperature of 100°C for 5 hours, and is reserved for use in the next step. The composition and mass percentage of the waste heating pad residue are: Fe2O3: 63.3%, C: 22.2%, SiO2: 8.6%, Al2O3: 3.5%, CaO: 2.4%; S2. First, tetrabutyl titanate, glacial acetic acid and anhydrous ethanol are mixed uniformly in a volume ratio of 5:1:9 to obtain a mixed solution; secondly, deionized water is added to the mixed solution, and the volume of the deionized water accounts for 8% of the total volume of the mixed solution to obtain a sol; thirdly, the waste heating pad residue powder after drying in step S1 is weighed and added to the sol, and the mass ratio of the waste heating pad residue powder to the tetrabutyl titanate in the sol is 1:3, and the mixture is mixed uniformly by magnetic stirring; finally, a gel is obtained after aging; S3. First, the gel prepared in step S2 is placed in an oven for drying at a temperature of 80°C for 10 hours to obtain a precursor dry gel; then, the precursor dry gel is placed in a tubular furnace and calcined at a constant temperature in a N2 atmosphere at a temperature of 400°C for 2 hours, and then cooled to room temperature with the furnace to obtain a Fe3O4 / TiO2 / C composite microwave absorbing material.

[0036] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A kind of Fe x O y The preparation method of / TiO2 / C composite microwave absorbing material is characterized in that: The following steps are involved: S1. After crushing and ball-milling the solid waste, the solid waste is sieved through a 100-300 mesh standard sieve, and the sieved solid waste powder is placed in an oven for drying at a temperature of 60° C. to 100° C. for a drying time of 4 to 8 hours, and is reserved for use in a subsequent step; the solid waste is waste toner or waste heating pad residue; S2. First, tetrabutyl titanate, glacial acetic acid, and anhydrous ethanol are mixed uniformly in a volume ratio of (2-8.5):(0-4):(4-12) to obtain a mixed solution; secondly, deionized water is added to the mixed solution, and the volume of the deionized water accounts for 1%-9% of the total volume of the mixed solution to obtain a sol; thirdly, the solid waste powder dried in step S1 is weighed and added to the sol, and the mass ratio of the solid waste powder to the tetrabutyl titanate in the sol is (1-2):(1-10), and the mixture is mixed uniformly by magnetic stirring; finally, a gel is obtained after aging; S3. First, the gel prepared in step S2 is placed in an oven for drying at a temperature of 60°C to 100°C for a drying time of 8 to 12 hours to obtain a precursor dry gel; Then, the precursor dry gel was placed in a tubular furnace and calcined at a constant temperature of 400°C to 1000°C in a N2 atmosphere for 2 h, and then cooled to room temperature to obtain Fe x O y / TiO2 / C composite microwave absorbing material.

2. A Fe according to claim 1 x O y The preparation method of / TiO2 / C composite microwave absorbing material is characterized in that: The chemical composition and mass percentage of the waste toner are: Fe2O3: 55.79%, SiO2: 17.32%, ZnO: 6.95%, C: 10.81%, CuO: 5.72%, CaO: 3.41%; the composition and mass percentage of the waste heating pad residue are: Fe2O3: 63.3%, C: 22.2%, SiO2: 8.6%, Al2O3: 3.5%, CaO: 2.4%.

3. A Fe prepared by the preparation method as claimed in claim 1 x O y Application of / TiO2 / C composite microwave absorbing materials in microwave absorption process.

4. The use according to claim 3, characterized in that: The Fe x O y The effective phase for microwave absorption in the / TiO2 / C composite microwave absorbing material is Fe x O y , TiO2 and C, the Fe x O y Fe or Fe3O4; Among them, Fe x O y As magnetic components, TiO2 and C serve as dielectric components.

5. The use according to claim 4, characterized in that: In the Fe x O y In the / TiO2 / C composite microwave absorbing material, the dielectric component TiO2 is wrapped around the magnetic component Fe x O y Outside the composite absorbing material, the dielectric component C is evenly distributed in the composite absorbing material.

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