Method and device for removing perfluoroalkyl compounds in soil solid waste by electromagnetic induction zero-valent iron

Abstract

The application discloses a kind of electromagnetic induction zero-valent iron soil solid waste perfluoroalkyl compound removal method and device, it is related to environmental protection equipment technical field.The device includes spiral feeder, feed tank, energy recovery preheating section, electromagnetic heating section, medium-high frequency power supply, heating coil and the like.Perfluoroalkyl compound-containing material is mixed with zero-valent iron particles, after preheating, into electromagnetic heating section, zero-valent iron is inductive heating in alternating electromagnetic field, in situ heating and reducing degradation perfluoroalkyl compound, and zero-valent iron can be recycled and used.The application breaks through the limitation of traditional single physical thermal desorption or chemical adsorption, realizes "heating-degradation" simultaneously, and fundamentally improves the thoroughness of pollutant removal.The application can realize heating and degradation simultaneously, with high energy efficiency and complete removal.The whole device has simple structure, can be operated continuously, has strong adaptability, and has good engineering application prospect.

Description

Technical Field

[0001] This invention relates to the field of environmental protection equipment technology, and in particular to a method and apparatus for removing perfluoroalkyl compounds from soil solid waste using electromagnetic induction zero-valent iron. Background Technology

[0002] Perfluoroalkyl compounds (PFAS) are widely used in fire-fighting foams, surface coatings, and food packaging due to their extremely high chemical stability and hydrophobic and oleophobic properties. However, their persistence, bioaccumulation, and potential toxicity in the environment have attracted global attention. Soil and solid waste are important environmental sinks for PFAS, and how to efficiently and thoroughly remove PFAS from them has become a current challenge in environmental governance.

[0003] Physical remediation technologies primarily rely on physical means to separate or immobilize pollutants, with adsorption and thermal desorption being commonly used methods. Adsorption is a widely applied strategy, with commonly used materials including clay minerals, activated carbon, and biochar. However, this method cannot completely remove perfluoroalkyl compounds (PFAS) from the system, only achieving interphase transfer of pollutants, requiring further treatment. Thermal desorption technology uses high-temperature heating to volatilize PFAS; however, its decomposition efficiency is limited, making it difficult to achieve complete decomposition of PFAS. It also suffers from high treatment costs and low energy efficiency, especially external heating methods which exhibit significant energy transfer losses and uneven heating. Therefore, there is an urgent need to develop a highly efficient, thorough, and economically feasible PFAS treatment technology for soil and solid waste. Summary of the Invention

[0004] The purpose of this invention is to provide a method and apparatus for removing perfluoroalkyl compounds from soil solid waste using electromagnetic induction zero-valent iron, in order to solve the problems existing in the prior art.

[0005] To achieve the above objectives, this invention provides an electromagnetic induction device for removing perfluoroalkyl compounds from soil solid waste containing zero-valent iron, comprising a screw feeder, a feed hopper, an energy recovery preheating section, an electromagnetic heating section, a medium-high frequency power supply, a heating coil, a screw discharge mechanism, a discharge port, a cooling water pipe, and an exhaust port; the screw feeder is connected to the feed hopper and is used to continuously convey contaminated material mixed with zero-valent iron particles to the energy recovery preheating section; the energy recovery preheating section is located at the front end of the electromagnetic heating section and is used to preheat the contaminated material using the waste heat of the reaction tail gas; the electromagnetic heating... The section is externally wound with a heating coil, which is electrically connected to a medium-high frequency power supply. This coil generates an alternating electromagnetic field inside the electromagnetic heating section, causing zero-valent iron particles in the contaminated material to heat up in situ, thus reducing and degrading perfluoroalkyl compounds. The screw discharge mechanism is located at the end of the electromagnetic heating section and connected to the discharge port for discharging the treated material. The cooling water pipe is located on the outer wall of the electromagnetic heating section for temperature control. The exhaust port is located above the energy recovery preheating section and / or the electromagnetic heating section for discharging the gases produced by the reaction.

[0006] Preferably, the zero-valent iron particles have a diameter of 1 mm to 5 mm and account for 25% to 75% of the weight of the contaminant.

[0007] Preferably, the residence time of the contaminant in the energy recovery preheating section is 10 min to 20 min, and the residence time of the contaminant in the electromagnetic heating section is 30 min to 60 min.

[0008] Preferably, the wall material of the electromagnetic heating section is non-magnetic austenitic stainless steel.

[0009] Preferably, the non-magnetic austenitic stainless steel is austenitic 304 stainless steel or austenitic 316 stainless steel.

[0010] Preferably, the frequency of the medium-high frequency power supply is 30kHz to 80kHz, the heating power per kilogram of contaminated material in the electromagnetic heating section is 1kW to 15kW, and the cavity temperature of the electromagnetic heating section is 100℃ to 350℃.

[0011] Preferably, the zero-valent iron particles are separated and recovered by magnetic separation or sieving after the reaction, and can be recycled 5 to 8 times.

[0012] The present invention also provides a method for removing perfluoroalkyl compounds from soil solid waste using electromagnetic induction with the above-mentioned device, comprising the following steps: Step 1: Mix the contaminant containing perfluoroalkyl compounds with zero-valent iron particles in a certain proportion; Step 2: The mixture is continuously conveyed to the energy recovery preheating section via a screw feeder and feed box, where it is preheated using the waste heat from the reaction tail gas; Step 3: The preheated material enters the electromagnetic heating section. Under the action of the alternating electromagnetic field generated by the heating coil driven by the medium- and high-frequency power supply, the zero-valent iron particles are induced to heat up, causing the internal temperature of the system to rise rapidly to 100-350°C and remain there for 30-60 minutes, thereby achieving the desorption and reduction degradation of perfluoroalkyl compounds. Step 4: After the reaction is complete, the material is discharged through the discharge port by the screw conveyor, and the generated gas is discharged through the exhaust port. Step 5: The processed zero-valent iron particles are recycled by magnetic separation or sieving for reuse.

[0013] Preferably, the diameter of the zero-valent iron particles is 1 mm to 5 mm, and their weight ratio to the contaminant material is 25% to 75%; the residence time in the energy recovery preheating section is 10 min to 20 min.

[0014] Preferably, the frequency of the medium-high frequency power supply is 30kHz to 80kHz, and the heating power per kilogram of contaminated material in the electromagnetic heating section is 1kW to 15kW.

[0015] Compared with the prior art, the present invention has the following advantages and technical effects: The present invention provides a method and apparatus for removing perfluoroalkyl compounds from soil solid waste using electromagnetic induction zero-valent iron (ZVFe). This method couples the electromagnetic induction heating characteristics of ZVFe with its reduction and degradation function, overcoming the limitations of traditional single physical thermal desorption or chemical adsorption. It achieves simultaneous "heating-degradation," fundamentally improving the thoroughness of pollutant removal. Employing an internal induction heating mode within the reaction system, compared to traditional external heating technology, it avoids energy conduction losses and significantly improves energy utilization efficiency. Targeted optimization of key parameters such as ZVFe particle size, mixing ratio, heating power, and residence time constructs a synergistic system, significantly improving reaction rate and defluorination efficiency. The apparatus integrates an energy recovery preheating section and a non-magnetic austenitic stainless steel heating chamber wall, achieving energy saving in pretreatment and adapting to electromagnetic induction environments, enhancing system stability and scenario adaptability. ZVFe undergoes only a redox cycle during the reaction, without irreversible consumption. After the reaction, it can be efficiently recovered through simple separation processes such as magnetic separation and sieving, significantly reducing consumable costs and minimizing secondary solid waste generation. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention.

[0017] Figure 1 This is a schematic diagram of the electromagnetic induction zero-valent iron soil solid waste perfluoroalkyl compound removal device of the present invention.

[0018] In the diagram: 1. Screw feeder; 2. Feed box; 3. Energy recovery preheating section; 4. Electromagnetic heating section; 5. Medium and high frequency power supply; 6. Heating coil; 7. Screw discharge mechanism; 8. Discharge port; 9. Cooling water pipe; 10. Exhaust port. Detailed Implementation

[0019] It should be noted that, unless otherwise specified, the embodiments and features described in this invention can be combined with each other. The described embodiments are merely some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this invention. The invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0020] like Figure 1 As shown, this invention provides an electromagnetic induction device for removing perfluoroalkyl compounds from soil solid waste containing zero-valent iron, comprising a screw feeder 1, a feed box 2, an energy recovery preheating section 3, an electromagnetic heating section 4, a medium-high frequency power supply 5, a heating coil 6, a screw discharge mechanism 7, a discharge port 8, a cooling water pipe 9, and an exhaust port 10; the screw feeder 1 is connected to the feed box 2 and is used to continuously convey the contaminated material mixed with zero-valent iron particles to the energy recovery preheating section 3; the energy recovery preheating section 3 is located at the front end of the electromagnetic heating section 4 and is used to preheat the contaminated material using the waste heat of the reaction tail gas; the electromagnetic heating section... 4. An external heating coil 6 is wound around the outside of the electromagnetic heating section 4. The heating coil 6 is electrically connected to the medium-high frequency power supply 5 and is used to generate an alternating electromagnetic field inside the electromagnetic heating section 4, so that the zero-valent iron particles in the contaminated material are induced to heat up, and the perfluoroalkyl compounds are heated in situ and reduced and degraded. The screw discharge mechanism 7 is set at the end of the electromagnetic heating section 4 and is connected to the discharge port 8 for discharging the processed material. The cooling water pipe 9 is set on the outside of the wall of the electromagnetic heating section 4 for temperature control. The exhaust port 10 is set above the energy recovery preheating section 3 and / or the electromagnetic heating section 4 for discharging the gas generated by the reaction.

[0021] The pollutant material mixed with zero-valent iron particles is continuously conveyed to the energy recovery preheating section 3 through the screw feeder 1 and the feed box 2. It is preheated using the waste heat of the reaction tail gas and then enters the electromagnetic heating section 4. Under the action of the alternating electromagnetic field generated by the heating coil 6 driven by the medium-high frequency power supply 5, the zero-valent iron particles are induced to heat up, generate heat in situ and reduce and degrade PFAS. This can realize direct heat generation inside the reaction system, avoid energy conduction loss, and greatly improve energy utilization efficiency. At the same time, heating and degradation are carried out simultaneously, which improves the thoroughness of pollutant removal from the source.

[0022] The scheme was further optimized so that the diameter of the zero-valent iron particles was 1mm to 5mm, and their weight ratio of the pollutant material was 25% to 75%.

[0023] By controlling the diameter of zero-valent iron (PFAS) particles to between 1 mm and 5 mm, a strong induced heating effect can be ensured in the alternating electromagnetic field, improving the heat generation efficiency per unit volume. This avoids agglomeration, increased transport resistance, and difficulties in magnetic separation caused by excessively fine particles, while preventing excessively large particles from reducing specific surface area and decreasing reduction reaction efficiency. Thus, a balance between heating performance and reactivity is achieved. The dosage is controlled between 25 wt% and 75 wt%. A lower proportion ensures the formation of continuous induced heating points in the system, achieving effective temperature rise; a higher proportion enhances the electromagnetic coupling effect between particles and improves electron supply capacity, thereby strengthening the reduction and degradation reaction of PFAS.

[0024] The scheme was further optimized so that the residence time of the contaminant in the energy recovery preheating section 3 is 10 min to 20 min, and the residence time of the contaminant in the electromagnetic heating section 4 is 30 min to 60 min.

[0025] By controlling the residence time in the preheating section to 10–20 minutes, the waste heat from the tail gas generated in the electromagnetic heating section 4 can be used to achieve uniform heating of the material and promote the initial desorption of pollutants, while avoiding excessive residence time that would reduce the system's processing efficiency. Controlling the residence time in the heating section to 30–60 minutes ensures that the zero-valent iron particles are fully induced to heat up and maintain a stable high-temperature reaction environment, allowing the perfluoroalkyl compounds to complete the continuous process from desorption, reduction bond breaking to defluorination degradation. If the time is too short, the reaction will be incomplete, while if it is too long, energy consumption will increase and the efficiency improvement will be limited.

[0026] To further optimize the design, the wall material of electromagnetic heating section 4 is made of non-magnetic austenitic stainless steel.

[0027] By selecting non-magnetic austenitic stainless steel as the wall material for electromagnetic heating section 4, this type of material does not generate significant induced heating in alternating electromagnetic fields. This avoids the heating energy being consumed by the cavity wall, allowing the electromagnetic energy to primarily act on the zero-valent iron particles, thereby improving heating efficiency. Simultaneously, austenitic stainless steel has excellent high-temperature resistance and corrosion resistance, resisting the corrosive effects of fluorine-containing gases and reaction byproducts, ensuring long-term stable operation of the device.

[0028] Further optimization of the scheme involves using non-magnetic austenitic stainless steel, specifically austenitic 304 stainless steel or austenitic 316 stainless steel.

[0029] By selecting austenitic 304 or 316 stainless steel, the non-magnetic, high-temperature resistance and corrosion resistance properties can be further optimized to meet different working conditions and avoid structural deformation or safety risks caused by local overheating of the vessel wall.

[0030] Further optimization of the scheme: the frequency of the medium-high frequency power supply 5 is 30kHz to 80kHz, the heating power per kilogram of contaminated material in the electromagnetic heating section 4 is 1kW to 15kW, and the cavity temperature of the electromagnetic heating section 4 is 100℃ to 350℃.

[0031] By controlling the frequency between 30kHz and 80kHz, stable eddy currents and hysteresis losses can be generated in zero-valent iron particles, achieving high induction heating efficiency. Too low a frequency will reduce the heating rate, while too high a frequency will reduce the electromagnetic penetration depth, leading to uneven heating within the material and increased equipment energy consumption. Power control between 1 and 15kW / kg and temperature control between 100℃ and 350℃ can efficiently remove fluoride while avoiding changes in soil mineral structure or sintering of solid waste matrix, reducing the risk of generating volatile fluorine byproducts and extending equipment lifespan.

[0032] The scheme was further optimized so that the zero-valent iron particles could be separated and recovered by magnetic separation or sieving after the reaction, and could be recycled 5 to 8 times.

[0033] Zero-valent iron particles can be recovered by magnetic separation or sieving. Taking advantage of the fact that zero-valent iron only undergoes redox cycles in the reaction and does not produce irreversible consumption, it can be recycled 5 to 8 times, which greatly reduces the cost of consumables and reduces the generation of secondary solid waste.

[0034] The present invention also provides a method for removing perfluoroalkyl compounds from soil solid waste using electromagnetic induction with the above-mentioned device, comprising the following steps: Step 1: Mix the contaminant containing perfluoroalkyl compounds with zero-valent iron particles in a certain proportion; Step 2: The mixture is continuously conveyed to the energy recovery preheating section 3 via the screw feeder 1 and the feed box 2, where it is preheated using the waste heat of the reaction tail gas; Step 3: The preheated material enters the electromagnetic heating section 4. Under the action of the alternating electromagnetic field generated by the heating coil 6 driven by the medium-high frequency power supply 5, the zero-valent iron particles are induced to heat up, causing the internal temperature of the system to rise rapidly to 100-350℃ and remain there for 30-60 minutes, thereby achieving the desorption and reduction degradation of perfluoroalkyl compounds. Step 4: After the reaction is complete, the material is discharged through the screw discharge mechanism 7 and the discharge port 8, and the generated gas is discharged through the exhaust port 10. Step 5: The processed zero-valent iron particles are recycled by magnetic separation or sieving for reuse.

[0035] By using the above methods and steps, PFAS-containing pollutants are mixed with zero-valent iron and then preheated, degraded by electromagnetic induction heating, discharged, and recovered from zero-valent iron in sequence. This process can achieve continuous, efficient, and energy-saving PFAS removal and significantly reduce operating costs.

[0036] Further optimization of the scheme resulted in zero-valent iron particles with a diameter of 1mm–5mm, accounting for 25%–75% of the weight of the contaminant; the residence time in the energy recovery preheating section 3 was 10min–20min. Parameter optimization in this method can further improve heating uniformity and degradation efficiency, ensuring sufficient preheating without reducing the overall processing throughput.

[0037] Further optimization of the scheme involves using a medium-high frequency power supply 5 with a frequency of 30kHz to 80kHz, and a heating power of 1kW to 15kW per kilogram of contaminated material in the electromagnetic heating section 4. Through the control of electromagnetic parameters in this method, efficient induction heating of zero-valent iron and rapid reduction and degradation of PFAS can be achieved, while avoiding excessive energy consumption and thermal damage to the equipment.

[0038] The electromagnetic induction zero-valent iron soil solid waste perfluoroalkyl compound removal device provided by this invention has the following overall implementation process: First, contaminated soil or solid waste containing perfluoroalkyl compounds is mixed with zero-valent iron particles with a diameter of 1-5 mm at a weight ratio of 25%-75%. The mixture is fed into the feed box 2 through a screw feeder 1 and continuously conveyed to the energy recovery preheating section 3. In the energy recovery preheating section 3, the material is preheated using the waste heat of the high-temperature exhaust gas discharged from the electromagnetic heating section 4, with a residence time of 10-20 minutes, so that the material temperature is initially raised and partial desorption of PFAS is promoted. The preheated material enters the electromagnetic heating section 4, the wall of which is made of non-magnetic austenitic 304 or 316 stainless steel. The medium-high frequency power supply 5 is started, the frequency is set to 30-80 kHz, and an alternating current is input to the heating coil 6 wound around the outside of the electromagnetic heating section 4, thereby generating an alternating electromagnetic field inside the electromagnetic heating section 4. Zero-valent iron particles mixed in the material generate eddy current and hysteresis losses under the action of an alternating magnetic field, achieving rapid induction heating of the particles themselves, raising the internal temperature of the system to 100–350°C. During the heating process, zero-valent iron acts as an electron donor, undergoing a surface oxidation reaction, releasing electrons and promoting the reduction and breaking of stable CF bonds in PFAS molecules, thus achieving defluorination and degradation of pollutants. The material stays in the electromagnetic heating section 4 for 30–60 minutes, during which the screw discharge mechanism 7 rotates slowly, ensuring thorough mixing and close contact between the material and the zero-valent iron particles. After the reaction is complete, the treated soil or solid waste is discharged through the screw discharge mechanism 7 via the discharge port 8, and the generated fluorine-containing gas is discharged through the exhaust port 10, which can be used for waste heat utilization or subsequent treatment. Circulating water in the cooling water pipe 9 cools the walls of the electromagnetic heating section 4 to prevent overheating. The zero-valent iron particles in the discharged material can be separated and recovered by magnetic separation or sieving, and recycled 5–8 times.

[0039] The electromagnetic induction zero-valent iron (ZVFe) soil solid waste perfluoroalkyl compound (PFAS) removal device provided by this invention achieves direct heat generation within the reaction system through the induced heating of ZVFe in an alternating electromagnetic field, avoiding energy conduction losses associated with traditional external heating and significantly improving energy utilization efficiency. ZVFe simultaneously acts as a heating element and reducing agent, reducing and degrading PFAS under high-temperature conditions. This synergistic effect of thermal desorption and chemical reduction achieves complete removal of PFAS rather than simple transfer, significantly improving removal and defluorination rates. The device integrates an energy recovery preheating section 3, utilizing waste heat from the exhaust gas to preheat the feed, further reducing overall system energy consumption. By optimizing key parameters such as ZVFe particle size, dosage, heating power, temperature, and residence time, a synergistic efficiency system is constructed, ensuring efficient degradation while avoiding energy waste and equipment damage. The electromagnetic heating section 4 uses non-magnetic austenitic stainless steel for its walls, preventing self-heating of the chamber and improving the efficiency of electromagnetic energy transfer to ZVFe particles, while also exhibiting good corrosion resistance. ZVFe can be easily recovered and recycled multiple times through magnetic separation or sieving, significantly reducing consumable costs and secondary solid waste generation. The entire device has a simple structure, can operate continuously, is highly adaptable, and has good prospects for engineering applications.

[0040] Example 1 Zero-valent iron particles with a diameter of 1 mm were selected and mixed at a ratio of 25% of the soil weight. Using the device of this invention, the soil was propelled by a screw feeder 1 to the energy recovery preheating section 3 for preheating. The contaminated soil remained in the preheating section for 20 minutes, then rolled with the rotating drum to the electromagnetic induction heating section 4, where it remained for 60 minutes. The walls of the electromagnetic heating section 4 were made of non-magnetic austenitic 304 stainless steel. The medium-high frequency power supply 5 used a frequency of 30 kHz, with a heating power of 1 kW per kilogram of soil in the heating section, and the temperature inside the heating section was controlled at 100℃. The experiment was conducted using perfluorooctanoic acid (PFOA) in PFAS as an example. Soil containing 10 ppm PFOA was treated, and the PFOA removal rate reached 20.55%, and the defluorination rate reached 10.63%.

[0041] Example 2 Zero-valent iron particles with a diameter of 3mm were selected and mixed with the soil at a weight ratio of 75% iron powder. Using the device of this invention, the soil was fed into the feed box 2 via a screw feeder 1 for preheating. The contaminated soil remained in the preheating section for 10 minutes, then rolled with the rotating drum to the electromagnetic heating section 4, where it remained for 30 minutes. The walls of the electromagnetic heating section 4 were made of non-magnetic austenitic 316 stainless steel. The medium-high frequency power supply 5 used a frequency of 50kHz, with a heating power of 8kW per kilogram of soil in the heating section, and the temperature inside the heating section was controlled at 218℃. Treatment of soil containing 10ppm PFOA showed a PFOA removal rate of 91.07% and a defluorination rate of 39.76%.

[0042] Example 3 Zero-valent iron particles with a diameter of 5mm were selected and mixed with the soil at a ratio of 50% by weight of iron powder. Using the device of this invention, the soil was fed into the feed box 2 via a screw feeder 1 for preheating. The contaminated soil remained in the preheating section for 15 minutes, then rolled with the rotating drum to the electromagnetic heating section 4, where it remained for 40 minutes. The walls of the electromagnetic heating section 4 were made of non-magnetic austenitic 316 stainless steel. The medium-high frequency power supply 5 used an 80kHz frequency, with a heating power of 15kW per kilogram of soil in the heating section, and the temperature inside the heating section was controlled at 350℃. Treatment of soil containing 10ppm PFOA showed a PFOA removal rate of 99.93% and a defluorination rate of 63.21%.

[0043] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A device for removing perfluoroalkyl compounds from soil solid waste using electromagnetic induction zero-valent iron, characterized in that, The system includes a screw feeder (1), a feed box (2), an energy recovery preheating section (3), an electromagnetic heating section (4), a medium-high frequency power supply (5), a heating coil (6), a screw discharge mechanism (7), a discharge port (8), a cooling water pipe (9), and an exhaust port (10). The screw feeder (1) is connected to the feed box (2) and is used to continuously transport contaminant material mixed with zero-valent iron particles to the energy recovery preheating section (3). The energy recovery preheating section (3) is located at the front end of the electromagnetic heating section (4) and is used to preheat the contaminant material using the waste heat of the reaction tail gas. The electromagnetic heating section (4) is externally wound with a heating coil (6). The heating coil (6) is electrically connected to the medium-high frequency power supply (5) to generate an alternating electromagnetic field inside the electromagnetic heating section (4), causing the zero-valent iron particles in the contaminated material to be induced to heat up, and to heat and reduce perfluoroalkyl compounds in situ; the screw discharge mechanism (7) is located at the end of the electromagnetic heating section (4) and connected to the discharge port (8) to discharge the processed material; the cooling water pipe (9) is located on the outside of the wall of the electromagnetic heating section (4) for temperature control; the exhaust port (10) is located above the energy recovery preheating section (3) and / or the electromagnetic heating section (4) to exhaust the gas generated by the reaction. The zero-valent iron particles have a diameter of 1 mm to 5 mm and account for 25% to 75% of the weight of the contaminant. The frequency of the medium-high frequency power supply (5) is 30kHz to 80kHz, the heating power of each kilogram of pollutant in the electromagnetic heating section (4) is 1kW to 15kW, and the cavity temperature of the electromagnetic heating section (4) is 100℃ to 350℃.

2. The electromagnetic induction zero-valent iron soil solid waste perfluoroalkyl compound removal device according to claim 1, characterized in that, The residence time of the pollutant in the energy recovery preheating section (3) is 10 min to 20 min, and the residence time of the pollutant in the electromagnetic heating section (4) is 30 min to 60 min.

3. The electromagnetic induction zero-valent iron soil solid waste perfluoroalkyl compound removal device according to claim 1, characterized in that, The wall material of the electromagnetic heating section (4) is non-magnetic austenitic stainless steel.

4. The electromagnetic induction zero-valent iron soil solid waste perfluoroalkyl compound removal device according to claim 3, characterized in that, The non-magnetic austenitic stainless steel is austenitic 304 stainless steel or austenitic 316 stainless steel.

5. The electromagnetic induction zero-valent iron soil solid waste perfluoroalkyl compound removal device according to claim 1, characterized in that, The zero-valent iron particles are separated and recovered by magnetic separation or sieving after the reaction, and can be recycled 5 to 8 times.

6. A method for removing perfluoroalkyl compounds from soil solid waste using electromagnetic induction with the apparatus described in any one of claims 1 to 5, characterized in that, Includes the following steps: Step 1: Mix the contaminant containing perfluoroalkyl compounds with zero-valent iron particles in a certain proportion; Step 2: The mixture is continuously conveyed to the energy recovery preheating section (3) via the screw feeder (1) and the feed box (2) to preheat using the waste heat of the reaction tail gas; Step 3: The preheated material enters the electromagnetic heating section (4). Under the action of the alternating electromagnetic field generated by the heating coil (6) driven by the medium-high frequency power supply (5), the zero-valent iron particles are induced to heat up, so that the internal temperature of the system rises rapidly to 100-350℃ and stays for 30-60 minutes to achieve the desorption and reduction degradation of perfluoroalkyl compounds. Step 4: After the reaction is completed, the material is discharged through the discharge port (8) by the screw discharge mechanism (7), and the generated gas is discharged through the exhaust port (10); Step 5: The processed zero-valent iron particles are recycled by magnetic separation or sieving for reuse.

7. The method according to claim 6, characterized in that, The zero-valent iron particles have a diameter of 1 mm to 5 mm and account for 25% to 75% of the weight of the pollutant; the residence time in the energy recovery preheating section (3) is 10 min to 20 min.

8. The method according to claim 6, characterized in that, The frequency of the medium-high frequency power supply (5) is 30kHz to 80kHz, and the heating power of each kilogram of pollutant material in the electromagnetic heating section (4) is 1kW to 15kW.

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