Porous iron-based carbon block, method for preparing the same, and use thereof

Abstract

The application discloses a kind of porous iron-based carbon block and its preparation method and application.The processed Chinese fir wood block is soaked with methanol, dried, then the wood block after drying treatment is soaked with acetylacetone ferrous solution, dried, then the dried wood block is placed into a tube furnace under nitrogen atmosphere and calcined continuously, to obtain acetylacetone ferrous-loaded carbon block;The acetylacetone ferrous-loaded carbon block is soaked with methanol and ultrapure water for a period of time, dried, to obtain a porous iron-based carbon block.The porous iron-based carbon block has excellent photo-thermal desalination performance, is cheap and easy to obtain, and has a significant effect of removing VOCs while desalinating.

Description

Technical Field

[0001] This invention relates to a porous iron-based carbon block, its preparation method, and its application, specifically to a porous iron-based carbon block for simultaneous removal of salt and VOCs from water, its preparation method, and its application, belonging to the field of photothermal material preparation technology. Background Technology

[0002] Since the beginning of the 21st century, with the continuous development of society, the demand for energy and water resources has been increasing. To address the energy crisis, solar thermal desalination technology has been continuously developed. Traditional seawater desalination technologies, such as ion exchange, while highly efficient, are complex and their practical applications are limited; electrodialysis, while selective, is difficult to treat high-concentration wastewater; reverse osmosis is highly efficient but suffers from membrane damage; and membrane distillation is effective at removing pollutants but carries the risk of membrane fouling. Furthermore, these traditional methods require significant energy and are costly. In contrast, solar thermal desalination technology has a simple structure, produces high-purity desalinated seawater, and the steam generated during the desalination process can be indirectly used for power generation, achieving sustainable development.

[0003] Although solar thermal desalination technology has matured, certain problems remain in the evaporation process. Firstly, salt precipitation often occurs during desalination, depositing on the surface of the evaporation device. At certain concentrations, this salt weakens the device's lifespan and reduces light absorption, significantly impacting the solar thermal efficiency. Secondly, VOCs from seawater can enter the distilled water during evaporation, greatly increasing the risk to drinking water. In recent years, carbon-based materials have attracted widespread attention in seawater desalination due to their superior light absorption, biocompatibility, and stability. Modifying carbon-based materials to improve light absorption and desalination efficiency has become a promising research direction. Some studies have used noble metal-loaded plasma to prepare noble metal plasma blocks, demonstrating significant water evaporation and solar thermal conversion efficiencies. However, the preparation process is complex and costly, making it difficult to apply to complex and variable environments. Furthermore, the problem of VOCs migrating into the condensate during desalination remains unresolved. Therefore, there is an urgent need to develop a modified carbon-based material that can simultaneously remove VOCs during the desalination process while achieving high seawater desalination efficiency. Summary of the Invention

[0004] Purpose of the invention: The first purpose of the invention is to provide a porous iron-based carbon block; the second purpose of the invention is to provide a method for preparing the porous iron-based carbon block; and the third purpose of the invention is to provide the application of the porous iron-based carbon block in the simultaneous removal of VOCs from desalinated seawater.

[0005] Technical solution: The present invention provides a method for preparing porous iron-based carbon blocks, comprising the following steps:

[0006] (1) Soak the fir wood blocks in methanol and then dry them;

[0007] (2) Prepare ferrous acetylacetone solution, soak the wood blocks obtained in step (1) in ferrous acetylacetone solution, and dry them;

[0008] (3) The wood block obtained in step (2) is calcined in a nitrogen atmosphere to obtain a carbon block loaded with ferrous acetylacetone;

[0009] (4) Soak the carbon block loaded with ferrous acetylacetone in methanol, then soak it in ultrapure water, and dry it to obtain the desired porous iron-based carbon block.

[0010] Further, in step (1), the shape of the fir wood block is cylindrical, the length of the fir wood block is about 8.7 to 9.0 mm, and the diameter of the fir wood block is 35.2 to 35.5 mm.

[0011] Furthermore, in step (1), the soaking time is 24 to 48 hours.

[0012] Furthermore, in step (1), the drying temperature is 60-80℃ and the drying time is 6-12h.

[0013] Furthermore, in step (2), the concentration of the ferrous acetylacetone solution is 4-6 g / L, and the ferrous acetylacetone solution is ultrasonically dispersed for 20-40 min when it is prepared.

[0014] Furthermore, in step (2), the soaking time is 24-48 hours, the drying temperature is 60-80°C, and the drying time is 6-12 hours.

[0015] Furthermore, in step (3), during calcination, the wood block obtained in step (2) is placed on the oxidizing furnace boat and then placed into the tube furnace, where the heating rate of the tube furnace is 3-7℃ / min.

[0016] Furthermore, in step (3), the calcination temperature is 500-900℃ and the calcination time is 2-3h.

[0017] Further, in step (4), the soaking time is 24-48 hours, the continued soaking time is 12-48 hours, the drying temperature is 60-80°C, and the drying time is 6-12 hours.

[0018] The present invention also includes porous iron-based carbon blocks obtained by the preparation method described above.

[0019] The application of the porous iron-based carbon block described in this invention in the simultaneous removal of VOCs from desalinated seawater.

[0020] This invention provides a method for preparing porous iron-based carbon blocks that simultaneously desalinate and remove VOCs from water. Using inexpensive fir wood blocks as the matrix, pre-treated fir wood blocks are obtained by soaking in methanol, which extracts resins and gums from the wood blocks, improving the water transport capacity of the pores. Before soaking the dried wood blocks in a ferrous acetylacetone solution, ultrasonic dispersion ensures uniform dissolution of the ferrous acetylacetone, facilitating better bonding with the wood blocks. Soaking the dried wood blocks in the ferrous acetylacetone solution modifies the internal pores and oxygen-containing groups, enhancing hydrophilicity, resulting in ferrous acetylacetone-treated fir wood blocks after drying. The wood blocks are calcined into carbon blocks in a tube furnace under a nitrogen atmosphere. Finally, the carbon blocks are soaked successively in methanol and ultrapure water to remove impurities and gums, further optimizing the internal structure of the carbon blocks. After drying, ferrous acetylacetone-loaded carbon blocks are obtained. The porous iron-based carbon block possesses excellent hydrophilic and porous properties, which is beneficial for light energy absorption and water transport. Ferrous acetylacetone has a beneficial effect on the internal pores and oxygen-containing groups of the carbon block. The combination of ferrous acetylacetone and the carbon block allows the porous iron-based carbon block of this invention to significantly improve the efficiency of photothermal desalination and significantly increase the rate of VOC removal by activated persulfate. This makes the combination of ferrous acetylacetone and the carbon block more stable and also significantly improves the internal porosity of the carbon block.

[0021] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0022] (1) The porous iron-based carbon block of the present invention has excellent photothermal desalination performance, and is cheap and readily available. It has a significant effect on removing VOCs while desalinating.

[0023] (2) The preparation method of the present invention is simple. It can prepare photothermal devices with high efficiency of VOCs degradation and excellent evaporation performance by relying on ferrous acetylacetone and fir blocks for simple high-temperature calcination.

[0024] (3) The porous iron-based carbon block prepared by the present invention can ensure that the active sites are fully loaded inside the pores of the carbon block, which solves the problems of dispersion of active sites and low utilization rate of catalysts in the prior art and has high practical application value. Attached Figure Description

[0025] Figure 1 XRD patterns and Raman spectra of the porous iron-based carbon blocks prepared in Examples 1-5 were obtained;

[0026] Figure 2 SEM images of the porous iron-based carbon block prepared in Example 1 at different magnifications;

[0027] Figure 3 Elemental mapping image of the porous iron-based carbon block prepared in Example 1;

[0028] Figure 4 The images show the effect of porous iron-based carbon blocks obtained in Examples 1-5 on the removal of phenol from persulfate after activation.

[0029] Figure 5 The graph shows the phenol content in the condensate after photothermal evaporation of the porous iron-based carbon blocks obtained in Examples 1-5.

[0030] Figure 6 Image showing the effect of photothermal evaporation and simultaneous activation of persulfate removal of phenol by porous iron-based carbon blocks under real outdoor sunlight;

[0031] Figure 7 Desalination performance of porous iron-based carbon blocks at different temperatures was tested. Detailed Implementation

[0032] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0033] Example 1

[0034] (1) The cedar wood block, which is processed into a cylindrical shape with a thickness of about 8.7 mm and a diameter of about 35.2 mm, is soaked in methanol for 48 hours, and then dried at 60°C for 6 hours.

[0035] (2) Prepare a 4 g / L ferrous acetylacetone solution and ultrasonically disperse the prepared solution for 20 min. Soak the wood blocks dried in step (1) in the 4 g / L ferrous acetylacetone solution for an additional 12 h, and then dry them at 70 °C for 8 h.

[0036] (3) Place the dried wood block from step (2) on the oxidizing furnace boat, then put it into the tube furnace and continue to calcine it under a nitrogen atmosphere. The heating rate of the tube furnace is 5℃ / min. After heating to 500℃, keep it for 2 hours and then take out the carbon block to obtain carbon block loaded with ferrous acetylacetone.

[0037] (4) The carbon block loaded with ferrous acetylacetone was first soaked in methanol for 24 h, and then soaked in ultrapure water for 48 h. It was then dried at 60 °C for 6 h to obtain the desired porous iron-based carbon block FeCB-500.

[0038] Example 2

[0039] (1) The cedar wood block, which is processed into a cylindrical shape with a thickness of about 8.7 mm and a diameter of about 35.2 mm, is soaked in methanol for 48 hours, and then dried at 70°C for 8 hours.

[0040] (2) Prepare a 4 g / L ferrous acetylacetone solution and ultrasonically disperse the prepared solution for 30 min. Soak the wood blocks dried in step (1) in the 4 g / L ferrous acetylacetone solution for an additional 24 h, and then dry them at 70 °C for 8 h.

[0041] (3) Place the dried wood block from step (2) on the oxidizing furnace boat, then put it into the tube furnace and continue to calcine it under a nitrogen atmosphere. The heating rate of the tube furnace is 3℃ / min. After heating to 600℃, keep it for 2 hours and then take out the carbon block to obtain carbon block loaded with ferrous acetylacetone.

[0042] (4) The carbon block loaded with ferrous acetylacetone was first soaked in methanol for 24 h, and then soaked in ultrapure water for 48 h. It was then dried at 70 °C for 8 h to obtain the desired porous iron-based carbon block FeCB-600.

[0043] Example 3

[0044] (1) The cedar wood block, which is processed into a cylindrical shape with a thickness of about 8.7 mm and a diameter of about 35.2 mm, is soaked in methanol for 48 hours, and then dried at 80°C for 10 hours.

[0045] (2) Prepare a 4 g / L ferrous acetylacetone solution and ultrasonically disperse the prepared solution for 40 min. Soak the wood blocks dried in step (1) in the 4 g / L ferrous acetylacetone solution for an additional 36 h, and then dry them at 80 °C for 10 h.

[0046] (3) Place the dried wood block from step (2) on the oxidizing furnace boat, then put it into the tube furnace and continue to calcine it under a nitrogen atmosphere. The heating rate of the tube furnace is 7℃ / min. After heating to 700℃, keep it for 2 hours and then take out the carbon block to obtain carbon block loaded with ferrous acetylacetone.

[0047] (4) The carbon block loaded with ferrous acetylacetone was first soaked in methanol for 24 h, and then soaked in ultrapure water for 48 h. It was then dried at 80 °C for 10 h to obtain the desired porous iron-based carbon block FeCB-700.

[0048] Example 4

[0049] (1) The cedar wood block, which is processed into a cylindrical shape with a thickness of about 8.7 mm and a diameter of about 35.2 mm, is soaked in methanol for 48 hours, and then dried at 80°C for 12 hours.

[0050] (2) Prepare a 4 g / L ferrous acetylacetone solution and ultrasonically disperse the prepared solution for 40 min. Soak the wood blocks dried in step (1) in the 4 g / L ferrous acetylacetone solution for an additional 48 h, and then dry them at 800 °C for 12 h.

[0051] (3) Place the dried wood block from step (2) on the oxidizing furnace boat, then put it into the tube furnace and continue to calcine it under a nitrogen atmosphere. The heating rate of the tube furnace is 5℃ / min. After heating to 800℃, keep it for 2 hours and then take out the carbon block to obtain carbon block loaded with ferrous acetylacetone.

[0052] (4) The carbon block loaded with ferrous acetylacetone was first soaked in methanol for 24 h, and then soaked in ultrapure water for 48 h. It was then dried at 60 °C for 12 h to obtain the desired porous iron-based carbon block FeCB-800.

[0053] Example 5

[0054] (1) The cedar wood block, which is processed into a cylindrical shape with a thickness of about 8.7 mm and a diameter of about 35.2 mm, is soaked in methanol for 48 hours, and then dried at 60°C for 12 hours.

[0055] (2) Prepare a 4 g / L ferrous acetylacetone solution and ultrasonically disperse the prepared solution for 30 min. Soak the wood blocks dried in step (1) in the 4 g / L ferrous acetylacetone solution for an additional 48 h, and then dry them at 60 °C for 12 h.

[0056] (3) Place the dried wood block from step (2) on the oxidizing furnace boat, then put it into the tube furnace and continue to calcine it under a nitrogen atmosphere. The heating rate of the tube furnace is 5℃ / min. After heating to 900℃, keep it for 2 hours and then take out the carbon block to obtain carbon block loaded with ferrous acetylacetone.

[0057] (4) The carbon block loaded with ferrous acetylacetone was first soaked in methanol for 24 h, and then soaked in ultrapure water for 48 h. It was then dried at 60 °C for 12 h to obtain the desired porous iron-based carbon block FeCB-900.

[0058] XRD and Raman spectroscopy analyses were performed on the porous iron-based carbon blocks prepared in Examples 1-5, and the results are as follows: Figure 1 As shown. Figure 1 XRD patterns and Raman spectra of the porous iron-based carbon blocks prepared in Examples 1-5 were obtained. (a) is the XRD pattern of the porous iron-based carbon blocks prepared in Examples 1-5, and (b) is the Raman spectrum of the porous iron-based carbon blocks prepared in Examples 1-5. Figure 1 It can be seen that, Figure 1 In (a), the iron-based porous carbon block exhibits two diffraction peaks at 21.5° and 41.6°, corresponding to the (002) and (101) crystal planes of graphite carbon, respectively. The (002) crystal plane is formed by the interlayer stacking of aromatic segments, while the (101) crystal plane is formed by the planar arrangement of aromatic segments. The diffraction peaks are broad and weak, indicating a low crystallinity of the porous carbon block. Figure (b) shows the Raman spectrum, which also reveals impurities and defects in the carbon material, located at 1365 cm⁻¹.-1 The D peak at 1594 cm⁻¹ is related to lattice defects of carbon atoms in graphite, while the peak at 1594 cm⁻¹ is related to lattice defects of carbon atoms in graphite. -1 The G peak at that location and the sp of carbon atoms in the graphite layer 2 The in-plane stretching vibrations of the bond phonon mode are related. The D-to-G peak ratios of FeCB-500, FeCB-700, and FeCB-900 are 0.66, 0.78, and 1.06, respectively. The I-value of FeCB-500 is related to the in-plane stretching vibrations of the bond phonon mode. D / I G The smaller value means that FeCB-500 contains fewer impurities and has a higher degree of crystallinity.

[0059] Scanning electron microscopy analysis was performed on the porous iron-based carbon block FeCB-500 obtained in Example 1, and the results are as follows: Figure 2 As shown. Figure 2 The images show SEM images of the porous iron-based carbon block prepared in Example 1 at different magnifications. (a) is a 10µm frontal SEM image of the porous iron-based carbon block, (b) is a 50µm frontal SEM image of the porous iron-based carbon block, (c) is a 100µm side SEM image of the porous iron-based carbon block, and (d) is a 50µm side SEM image of the porous iron-based carbon block. Figure 2 As shown in (a) and (b), the surface of the FeCB-500 charcoal block exhibits a regular porous morphology, which originates from the tubular structure naturally present in wood. Figure 2 As shown in (c) and (d), the pores arranged neatly in the carbon block are mostly wide, generally greater than 20 μm, and penetrate the entire carbon block. This structure is beneficial for the water transport of the seawater to be desalinated, thereby improving the evaporation efficiency. In addition, these pores can refract incident light, improving light energy utilization; on the other hand, they can also increase the specific surface area, thereby enhancing the adsorption capacity of the porous carbon block for VOCs.

[0060] TEM-EDS elemental mapping image analysis was performed on the porous iron-based carbon block obtained in Example 1, and the results are as follows: Figure 3 As shown. Figure 3 The images shown are elemental mapping images of the porous iron-based carbon blocks prepared in Example 1, wherein (a) is a TEM-EDS elemental mapping image of the porous iron-based carbon block at 50 μm, (b) is a TEM-EDS elemental mapping image of C at 50 μm, (c) is a TEM-EDS elemental mapping image of Fe at 50 μm, (d) is a TEM-EDS elemental mapping image of the porous iron-based carbon block at 100 μm, (e) is an EDS elemental mapping image of C at 100 μm, and (f) is an EDS elemental mapping image of Fe at 100 μm. Figure 3 It is evident that FeCB-500 contains both C and Fe elements, with the Fe element evenly distributed throughout, thus successfully completing the modification.

[0061] Example 6: Performance testing of the porous iron-based carbon blocks prepared in Examples 1-5

[0062] 1. Performance test of persulfate-activated porous carbon blocks in degrading phenol

[0063] Phenol degradation: Before photothermal degradation, 20 mL of 1 mol / L NaCl, 1 mL of 1 mol / L phenol, 1.2 mL of 200 mmol / L potassium persulfate, and 17.8 mL of ultrapure water were added to five evaporating dishes. After thorough stirring, simulated saline water with a final persulfate concentration of 6 mmol / L was obtained. Porous iron-based carbon blocks prepared in Examples 1-5 were then placed in these solutions. The experiment used a xenon lamp fitted with an AM1.5 filter as the light source, with a light intensity of approximately 500 mW / cm². 2 First, a dark reaction was carried out in a light-shielded chamber for 30 minutes to reach adsorption-desorption equilibrium. After the dark reaction, a saline sample was collected. At regular intervals (120 min, 240 min, 360 min), 800 μL of the saline solution was collected and, together with 200 μL of methanol, was placed into a syringe with a 0.22 μm microporous membrane. Finally, the solution was injected into a liquid chromatography vial, which was then subjected to high-performance liquid chromatography (HPLC) for detection, thereby determining the change in phenol concentration in the saline solution at different time points. The results are as follows: Figure 4 As shown in the figure. A condensate collection hood was placed above the evaporator dish to collect distilled water at 120 min, 240 min, and 360 min, respectively, and then placed in a liquid chromatography vial for later use. The phenol content in the distilled water was then determined using high-performance liquid chromatography (HPLC), and the results are shown in the figure. Figure 5 As shown. A comparison was made with the sample without added potassium persulfate (0 mmol / L).

[0064] Figure 4 The images show the effect of porous iron-based carbon blocks obtained in Examples 1-5 on the removal of phenol from persulfate after activation. Figure 4 It is known that Fe can both alter the surface functional groups and hydrophilicity / hydrophobicity of porous iron-based carbon blocks, thus affecting the activation of persulfate, and may also activate persulfate itself. The removal of phenol using porous iron-based carbon blocks prepared at different calcination temperatures yielded the following results: Figure 4 As shown in (a), although the phenol concentration was increased to 0.75 mM, the removal rate of phenol by Fe-modified porous carbon blocks was still significantly improved. FeCB-900 removed phenol quickly in the first 60 minutes, but its rate decreased significantly with the consumption of persulfate and it could not completely remove phenol. Although FeCB-500 was slightly slower than FeCB-900 in the early stage of the experiment, its rate gradually increased as the experiment progressed, and it could completely remove phenol from the solution within 360 minutes. Figure 4(b) This diagram shows the effect of porous iron-based carbon blocks activating persulfate to remove phenol without the addition of persulfate. It can be seen that when no persulfate is added, the phenol removal effect is significantly reduced, and the reaction rate decreases significantly with increasing reaction time, far lower than the effect when persulfate is added.

[0065] Figure 5 The graph shows the phenol content in the condensate after photothermal evaporation of the porous iron-based carbon blocks prepared in Examples 1-5. Figure 5 It can be found that after adding potassium persulfate, the phenol content in the condensate of porous iron-based carbon blocks prepared at different calcination temperatures after photothermal evaporation is almost zero, which shows the excellent performance of persulfate-activated porous iron-based carbon blocks in photothermal degradation of phenol.

[0066] Example 7: Actual evaporation performance test of porous iron-based carbon blocks under sunlight

[0067] This experiment was conducted under actual sunlight. The experimental procedure was the same as in Example 6. 20 mL of 1 mol / L NaCl, 1 mL of 1 mol / L phenol, 1.2 mL of 200 mmol / L potassium persulfate, and 17.8 mL of ultrapure water were added to a beaker. After thorough stirring, a simulated brine was obtained. The porous iron-based carbon block FeCB-500 prepared in Example 1 was placed inside. A condensate collection hood was placed above the beaker, and then it was placed under sunlight. The intensity of the sunlight was measured using a photometer. Specific values ​​are shown below. Figure 6 (b) As shown on the left axis, it can be observed that the intensity of sunlight measured at different time points changes with time, further affecting the temperature of the liquid solution. In this experiment, the intensity of sunlight was measured every 30 minutes using a photometer, and the temperature of the liquid solution was measured every 30 minutes using a thermometer. Real-time records of the intensity of sunlight and the temperature of the liquid surface were obtained, as shown below. Figure 6 As shown in the figure. Every 30 minutes, a portion of the salt solution was transferred to a small vial for later use. Every 120 minutes, a portion of distilled water from the condensate collection hood was transferred to a small vial for later use. The phenol content in the salt solution and distilled water was then determined using high-performance liquid chromatography (HPLC), respectively. The results are shown in the figure. Figure 6 As shown.

[0068] Figure 6 The images show the effect of photothermal evaporation and simultaneous activation of persulfate to remove phenol from porous iron-based carbon blocks under real outdoor sunlight; (a) shows the changes in phenol concentration in saline and distilled water, and (b) shows the changes in outdoor light intensity and solution temperature during the experiment. Figure 6 (b) It is evident that the intensity of sunlight varies with time, reaching a maximum of 100 mW / cm². 2As time progresses, the intensity of sunlight increases, and the temperature of the solution at the surface also rises further. This is because sunlight heats the porous iron-based carbon block, creating a localized thermal effect that promotes the degradation of phenol under actual conditions. Figure 6 (a) It can be seen that the removal rate of phenol in the solution reached 86.24% at 360 min, while the residual amount of phenol in the evaporated water was only 6.05% at the highest point, and less than 1% at 360 min. Therefore, it has certain application potential under actual sunlight.

[0069] Example 8: Desalination Performance Test of Porous Iron-Based Carbon Blocks

[0070] Similar to Example 7, 40 mL of simulated saline solution was placed in an evaporating dish, and five groups were prepared. The porous iron-based carbon blocks from Examples 1-5 were placed above the liquid surface of each of the five groups, and then placed on an electronic balance and irradiated with an AM1.5 xenon lamp. The electronic balance was connected to a computer, and the evaporation mass of the simulated saline solution in the evaporating dish was recorded in real time using Serial Port Utility software, thereby calculating the evaporation rate and light energy utilization rate of the simulated saline solution.

[0071] Figure 7 The graph shows the desalination performance test results of porous iron-based carbon blocks in Examples 1-5. The 1-hour evaporation rates of FeCB-500, FeCB-700, and FeCB-900 are 3.65 kg / m³, respectively. -2 h -1 1.95kg m -2 h -1 3.17kg m -2 h -1 This indicates that FeCB-500 performs better in photothermal evaporation than other Fe-modified porous carbon blocks. This is mainly because at lower temperatures, the porous iron-based carbon blocks have a more complete pore structure, and their hydrophilicity and hydrophobicity are preserved, thereby improving the desalination evaporation performance. However, at higher temperatures, the degree of carbonization is more obvious, and the pore structure collapses, weakening the desalination evaporation performance.

Claims

1. A method for producing a porous iron-based carbon block, characterized by, The method comprises the following steps: (1) soaking Chinese fir wood pieces in methanol, and drying, wherein the Chinese fir wood pieces are in a cylindrical shape, the length of the Chinese fir wood pieces is 8.7-9.0 mm, and the diameter of the Chinese fir wood pieces is 35.2-35.5 mm; (2) preparing a solution of acetylacetone ferrous with a concentration of 4-6 g / L, soaking the wood pieces obtained in step (1) in the solution of acetylacetone ferrous for 24-48 h, and drying; (3) calcining the wood pieces obtained in step (2) under a nitrogen atmosphere to obtain carbon pieces loaded with acetylacetone ferrous, wherein the heating rate during calcination is 3-7 ℃ / min, the calcination temperature is 500-900 ℃, and the calcination time is 2-3 h; (4) soaking the carbon pieces loaded with acetylacetone ferrous in methanol, then continuing to soak in ultrapure water, and drying to obtain the desired porous iron-based carbon pieces.

2. The production method according to claim 1, characterized by, In step (1), the soaking time is 24-48 h, and the drying temperature is 60-80 ℃, and the drying time is 6-24 h.

3. The production method according to claim 2, characterized by, In step (2), the solution of acetylacetone ferrous is ultrasonically dispersed for 20-40 min when being prepared.

4. The method of claim 1, wherein, In step (2), the drying temperature is 60-80 ℃, and the drying time is 6-24 h.

5. The preparation method according to claim 1, characterized in that, In step (4), the soaking time is 24-48 h, the continuing soaking time is 24-48 h, the drying temperature is 60-80 ℃, and the drying time is 6-24 h.

6. The porous iron-based carbon pieces obtained by the preparation method in any one of claims 1-5.

7. The application of the porous iron-based carbon pieces in claim 6 in desalination of seawater and simultaneous removal of VOCs.

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