Low-cost sulfidized nano zero-valent iron synthesized from pyrite and its application

Abstract

The application discloses low-cost sulfidized nano zero-valent iron synthesized by using pyrite as raw material and application thereof. The low-cost sulfidized nano zero-valent iron is obtained by using cheap pyrite powder as raw material, adding a small amount of anhydrous FeCl3, and through ball milling, drying and hydrogen reduction. The pyrite powder to which a small amount of anhydrous FeCl3 is added is ball milled by using zirconia ball milling beads which are easy to clean but not easy to be polluted, and then the sulfidized nano zero-valent iron is prepared after drying and reduction. By adjusting parameters such as ball powder ratio, FeCl3 addition amount, heating rate and holding time, the low-cost sulfidized nano zero-valent iron with a particle size of 200-300 nm, zero-valent iron content accounting for more than 90% of total iron content and preparation cost being 11% of that of a laboratory liquid-phase synthesis method is prepared. The material can effectively degrade trichloroethylene (TCE) and florfenicol (FF), has a small hydrogen production amount and a high electron efficiency. The preparation method is simple and easy to operate, has a low cost and has a large-scale production prospect, the degradation performance of pollutants is close to that of the laboratory-prepared sulfidized nano zero-valent iron, and far exceeds that of nano zero-valent iron, and therefore the material has a prospect of being applied to actual groundwater pollution remediation.

Description

Technical Field

[0001] This invention belongs to the field of functional nanomaterials and technology, and in particular relates to a low-cost sulfide nano-zero-valent iron synthesized from pyrite and its applications. Background Technology

[0002] Sulfide-modified nano-zero-valent iron (SNZVI), as a product of sulfur modification of nano-zero-valent iron, exhibits enhanced hydrophobicity, reduced hydrogen evolution capacity, and enhanced electron transfer capacity compared to traditional nano-zero-valent iron due to the addition of sulfur. This results in better removal of organic pollutants such as TCEs, and it has been widely studied in soil and groundwater applications in recent years. Currently, the only synthesis method for SNZVI is the liquid-phase reduction method. This method is limited by the price of reducing agents, resulting in low yield, high cost, and difficulty in achieving large-scale production.

[0003] Gas-phase reduction and mechanical ball milling are currently mature methods for the large-scale preparation of nanoparticles. Hydrogen gas-phase reduction can well preserve the original morphology of the particles, but the cost of preparing the nanoscale precursors for reduction is high. Mechanical ball milling has advantages such as simple operation and low cost, but it also has disadvantages such as difficulty in guaranteeing particle morphology. Previous studies have directly ball-milled iron and sulfur powders, but due to the ductility of metals, the milled products can only reach the micrometer scale and are difficult to reach the nanometer scale, exhibiting lower specific surface area and activity compared to spherical SNZVI. Pyrite is more brittle than iron, making it easier to grind into nanoscale particles in multiple directions, and pyrite is inexpensive. Therefore, this patent uses ball milling to prepare nanoscale pyrite as a precursor for hydrogen reduction. Pyrite is ball-milled to the nanoscale using zirconia ball milling beads with higher hardness and easier cleaning, and FeCl3 is added during the process to reduce the difficulty of subsequent reduction. Then, it is reduced with hydrogen to prepare a low-cost sulfide nano-zero-valent iron material. Currently, there is no commercially available SNZVI produced industrially. Laboratory-synthesized SNZVI using liquid phase synthesis costs as much as 1253 yuan / kg, while the low-cost SNZVI synthesized using this method costs only 137 yuan / kg, and its performance is also quite similar, showing great promise for industrialization. In summary, this invention provides a new design concept and technical method reference for the preparation of sulfide nano-zero-valent iron materials. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by providing a low-cost sulfide nano-zero-valent iron synthesized from pyrite and its applications.

[0005] The objective of this invention is achieved through the following technical solution: a low-cost sulfide nano-zero-valent iron synthesized from pyrite, wherein the low-cost sulfide nano-zero-valent iron synthesized from pyrite is prepared by the following method:

[0006] (1) Pyrite powder, anhydrous FeCl3, a zirconia ball milling bead assembly, and anhydrous ethanol are placed in a ball mill jar. The zirconia ball milling bead assembly consists of zirconia ball milling bead A, zirconia ball milling bead B, and zirconia ball milling bead C. The diameter of zirconia ball milling bead A is 6.0-6.2 mm, the diameter of zirconia ball milling bead B is 3.0-3.2 mm, and the diameter of zirconia ball milling bead C is 2.0-2.2 mm. The mass ratio of zirconia ball milling bead A, zirconia ball milling bead B, and zirconia ball milling bead C is 1:1:4. The mass ratio of pyrite powder to the zirconia ball milling bead assembly is 1:20. The mass ratio of pyrite powder to anhydrous ethanol is 1 g: 1-3 mL. The mass of Fe in the anhydrous FeCl3 is 0%-10% of the mass of Fe in the pyrite powder.

[0007] (2) The ball mill jar was then placed on a planetary ball mill for ball milling. After ball milling, the pyrite powder was obtained by washing with water.

[0008] (3) After drying the pyrite powder obtained in step (2), small-particle-size pyrite powder blocks are obtained.

[0009] (4) Grind the small-particle-size pyrite powder blocks obtained in step (3) with a mortar and pestle to obtain nano-sized pyrite powder;

[0010] (5) Take the pyrite powder obtained in step (4) and spread it evenly in a porcelain boat. Place it in a reduction furnace and heat it to 500-650°C in a pure hydrogen atmosphere at a heating rate of 5-10°C / min. Hold it for 10-30 min and then continue heating to 900-1100°C at a heating rate of 0.5-2°C / min. Hold it for 60-180 min. Then switch to argon gas and cool it to room temperature in an argon atmosphere to obtain low-cost sulfide nano-zero-valent iron synthesized from pyrite.

[0011] Furthermore, the pyrite powder has a particle diameter of 40–45 μm.

[0012] Furthermore, the optimal mass ratio of Fe in the anhydrous FeCl3 to Fe in the pyrite powder is 0.075:1.

[0013] Furthermore, in step (2), the ball milling parameters are set to 400-450 rpm for 20-24 hours.

[0014] This invention also provides the application of low-cost sulfide nano-zero-valent iron synthesized from pyrite as raw material for the degradation of TCE in TCE-contaminated groundwater.

[0015] Furthermore, the specific steps include:

[0016] (a1) Using a TCE solution with a concentration of 50–80 μmol / L, under anaerobic conditions, simulate TCE-contaminated groundwater;

[0017] (a2) 0.1g of low-cost sulfide nano-zero-valent iron synthesized from pyrite was placed into 100mL of simulated TCE-contaminated groundwater and nitrogen was blown into the headspace of the container.

[0018] (a3) Place the container on a turner at room temperature and rotate it at 50 rpm for 7 to 10 days to degrade TCE in simulated TCE-contaminated groundwater.

[0019] This invention also provides the application of low-cost sulfide nano-zero-valent iron synthesized from pyrite as raw material for the degradation of FF in FF-contaminated groundwater.

[0020] Furthermore, the specific steps include:

[0021] (a1) Prepare FF solutions of 0.028–0.28 mmol / L and simulate FF contamination of groundwater under anaerobic conditions;

[0022] (a2) 0.1g of low-cost sulfide nano-zero-valent iron synthesized from pyrite was placed into 100mL of simulated FF-contaminated groundwater and nitrogen was blown into the headspace of the container.

[0023] (a3) Place the container on a turner at room temperature and rotate it at 50 rpm for 8-10 hours to degrade FF in simulated FF-contaminated groundwater.

[0024] The beneficial effects of this invention are:

[0025] (1) The preparation method of this low-cost sulfide nano zero-valent iron material is to first ball mill the relatively brittle pyrite powder to the nanoscale and then reduce it, which is simple and easy to operate;

[0026] (2) This preparation method can obtain sulfide nano-zero valent iron with properties close to those prepared in the laboratory, and the preparation cost is only 11% of that prepared in the laboratory, which has good industrialization value and prospects.

[0027] (3) The material can effectively degrade pollutants (TCE, FF) in simulated polluted groundwater, and produces less hydrogen and has high electron efficiency. Attached Figure Description

[0028] Figure 1 The graph shows the test results of the proportion of zero-valent iron content in the low-cost sulfide nano-zero-valent iron synthesized from pyrite as raw material obtained in Examples 1-3 and the sulfide nano-zero-valent iron prepared in the laboratory.

[0029] Figure 2 The images show transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDXPS) characterizations of ball-milled pyrite. Figure 2 (a) is a transmission electron microscope image of pyrite after ball milling. Figure 2 (b) is an energy dispersive X-ray spectrometer characterization of pyrite after ball milling;

[0030] Figure 3 The images show transmission electron microscopy and energy-dispersive X-ray spectroscopy characterizations of directly reduced ball-milled pyrite. Figure 3 (a) is a transmission electron microscope image of ball-milled pyrite after direct reduction. Figure 3 (b) Energy dispersive X-ray spectrometer characterization of ball-milled pyrite after direct reduction;

[0031] Figure 4 The images show transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDX) characterizations of low-cost sulfide nano-zero-valent iron synthesized from pyrite before reduction. Figure 4 (a) is a transmission electron microscope characterization image of low-cost sulfide nano-zero-valent iron synthesized from pyrite before reduction. Figure 4 (b) is the energy dispersive X-ray spectrometer characterization of low-cost sulfide nano-zero-valent iron synthesized from pyrite before reduction;

[0032] Figure 5 The images shown are transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDX) characterizations of the low-cost sulfide nano-zero-valent iron synthesized from pyrite in Example 3. Figure 5 (a) is a transmission electron microscope characterization image of the low-cost sulfide nano-zero-valent iron synthesized from pyrite as raw material obtained in Example 3. Figure 5 (b) is the energy dispersive X-ray spectrometer characterization of the low-cost sulfide nano-zero-valent iron synthesized from pyrite as raw material prepared in Example 3;

[0033] Figure 6 The particle size distribution test results of the low-cost sulfide nano-zero-valent iron synthesized from pyrite as raw material obtained in Examples 1-3 are shown in the figure.

[0034] Figure 7 X-ray diffraction patterns of low-cost sulfide nano-zero-valent iron synthesized from pyrite as raw material, prepared in Examples 1-3;

[0035] Figure 8 This is a comparison chart showing the preparation costs of low-cost sulfide nano-zero-valent iron synthesized from pyrite as raw material, prepared in Example 3, sulfide nano-zero-valent iron prepared by laboratory liquid-phase reduction method, and nano-zero-valent iron prepared by laboratory liquid-phase reduction method.

[0036] Figure 9 A comparison chart of the unit cost of low-cost sulfide nano-zero-valent iron synthesized from pyrite as raw material in Example 3 under different yields;

[0037] Figure 10 The graph shows the change of TCE content over time when low-cost sulfide nano-zero-valent iron synthesized from pyrite as raw material degrades TCE in simulated groundwater, as shown in Examples 1-3.

[0038] Figure 11 This is a comparison of the reaction rates of TCE degradation in simulated groundwater when low-cost sulfide nano-zero-valent iron synthesized from pyrite and prepared in Examples 1-3 is used.

[0039] Figure 12 The graph shows the change of FF content over time when low-cost sulfide nano-zero valent iron synthesized from pyrite as raw material degrades FF in simulated groundwater, as shown in Examples 1-3.

[0040] Figure 13 The graph shows a comparison of the degradation rates of FF in simulated groundwater using low-cost sulfide nano-zero-valent iron synthesized from pyrite as raw material, prepared in Examples 1-3. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0042] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; unless otherwise specified, the reagents and materials are commercially available.

[0043] This invention provides a low-cost sulfide nano-zero-valent iron synthesized from pyrite, which is prepared by the following method:

[0044] (1) Pyrite powder, anhydrous FeCl3, a zirconia ball milling bead assembly, and anhydrous ethanol are placed in a ball mill jar. The zirconia ball milling bead assembly consists of zirconia ball milling bead A, zirconia ball milling bead B, and zirconia ball milling bead C. The diameter of zirconia ball milling bead A is 6.0-6.2 mm, the diameter of zirconia ball milling bead B is 3.0-3.2 mm, and the diameter of zirconia ball milling bead C is 2.0-2.2 mm. The mass ratio of zirconia ball milling bead A, zirconia ball milling bead B, and zirconia ball milling bead C is 1:1:4. The mass ratio of pyrite powder to the zirconia ball milling bead assembly is 1:20. The mass ratio of pyrite powder to anhydrous ethanol is 1 g: 1-3 mL. The mass of Fe in the anhydrous FeCl3 is 0%-10% of the mass of Fe in the pyrite powder.

[0045] (2) The ball mill jar was then placed on a planetary ball mill for ball milling. After ball milling, the pyrite powder was obtained by washing with water.

[0046] (3) After drying the pyrite powder obtained in step (2), small-particle-size pyrite powder blocks are obtained.

[0047] (4) Grind the small-particle-size pyrite powder blocks obtained in step (3) with a mortar and pestle to obtain nano-sized pyrite powder;

[0048] (5) Take the pyrite powder obtained in step (4) and spread it evenly in a porcelain boat. Place it in a reduction furnace and heat it to the reduction temperature of 500-650℃ in a pure hydrogen atmosphere. The heating rate is 5-10℃ / min. Hold for 10-30min. Then continue to heat it to the reduction temperature of 900-1100℃ in a pure hydrogen atmosphere. The heating rate is 0.5-2℃ / min. Hold for 60-180min. Then switch to argon gas and cool to room temperature in an argon atmosphere to obtain low-cost sulfide nano-zero valent iron synthesized from pyrite.

[0049] The pyrite powder has a particle diameter of 40–45 μm.

[0050] The optimal mass ratio of Fe in the anhydrous FeCl3 to Fe in the pyrite powder is 0.075:1.

[0051] In step (2), the ball milling parameters are set to 400-450 rpm for 20-24 hours.

[0052] This invention also provides the application of low-cost sulfide nano-zero-valent iron synthesized from pyrite as raw material for the degradation of TCE in TCE-contaminated groundwater, specifically including the following steps:

[0053] (a1) Using a TCE solution with a concentration of 50–80 μmol / L, under anaerobic conditions, simulate TCE-contaminated groundwater;

[0054] (a2) 0.1g of low-cost sulfide nano-zero-valent iron synthesized from pyrite was placed into 100mL of simulated TCE-contaminated groundwater and nitrogen was blown into the headspace of the container.

[0055] (a3) Place the container on a turner at room temperature and rotate it at 50 rpm for 7 to 10 days to degrade TCE in simulated TCE-contaminated groundwater.

[0056] This invention also provides the application of low-cost sulfide nano-zero-valent iron synthesized from pyrite as raw material for the degradation of FF in FF-contaminated groundwater, specifically including the following steps:

[0057] (a1) Prepare FF solutions of 0.028–0.28 mmol / L and simulate FF contamination of groundwater under anaerobic conditions;

[0058] (a2) 0.1g of low-cost sulfide nano-zero-valent iron synthesized from pyrite was placed into 100mL of simulated FF-contaminated groundwater and nitrogen was blown into the headspace of the container.

[0059] (a3) Place the container on a turner at room temperature and rotate it at 50 rpm for 8-10 hours to degrade FF in simulated FF-contaminated groundwater.

[0060] Example 1: A preparation process of low-cost sulfide nano-zero-valent iron synthesized from pyrite.

[0061] (1) Take 15g of pyrite powder, 0.5g of anhydrous FeCl3 (the mass of Fe in the anhydrous FeCl3 is 2.5% of the mass of Fe in the pyrite powder), 50g of zirconia grinding beads A, 50g of zirconia grinding beads B, 200g of zirconia grinding beads C, and 30mL of anhydrous ethanol and place them in a grinding jar. The anhydrous ethanol is a grinding aid. The diameter of the zirconia grinding beads A is 6.0mm, the diameter of the zirconia grinding beads B is 3.0mm, and the diameter of the zirconia grinding beads C is 2.0mm.

[0062] (2) The ball mill jar was then placed on a planetary ball mill for ball milling at a speed of 450 rpm for 24 hours. After the ball milling was completed, the pyrite powder was obtained by washing with water.

[0063] (3) The pyrite powder obtained in step (2) is dried at 60°C for 8 hours to obtain small-particle-size pyrite powder blocks.

[0064] (4) Grind the small-particle-size pyrite powder blocks obtained in step (3) with a mortar and pestle to obtain nano-sized pyrite powder.

[0065] (5) Take 2.0g of nano-sized pyrite powder obtained in step (4) and spread it evenly in a ceramic boat. Place it in a reduction furnace and heat it to 600℃ in a pure hydrogen atmosphere at a heating rate of 5℃ / min. Hold it for 30min and then continue heating to 950℃ at a heating rate of 1℃ / min. Hold it for 120min. Then switch to argon gas and cool it to room temperature in an argon atmosphere. Remove the rubber tube at the end of the tubular furnace from the water surface and slowly shut off the argon gas to obtain low-cost sulfide nano-zero valent iron (Py-SNZVI) synthesized from pyrite.

[0066] Example 2: A preparation process of low-cost sulfide nano-zero-valent iron synthesized from pyrite.

[0067] (1) Take 15g of pyrite powder, 1.0g of anhydrous FeCl3 (the mass of Fe in the anhydrous FeCl3 is 5% of the mass of Fe in the pyrite powder), 50g of zirconia grinding beads A, 50g of zirconia grinding beads B, 200g of zirconia grinding beads C, and 30mL of anhydrous ethanol and place them in a grinding jar. The anhydrous ethanol is a grinding aid. The diameter of the zirconia grinding beads A is 6.0mm, the diameter of the zirconia grinding beads B is 3.0mm, and the diameter of the zirconia grinding beads C is 2.0mm.

[0068] (2) The ball mill jar was then placed on a planetary ball mill for ball milling at a speed of 450 rpm for 24 hours. After the ball milling was completed, the pyrite powder was obtained by washing with water.

[0069] (3) The pyrite powder obtained in step (2) is dried at 60°C for 8 hours to obtain small-particle-size pyrite powder blocks.

[0070] (4) Grind the small-particle-size pyrite powder blocks obtained in step (3) with a mortar and pestle to obtain nano-sized pyrite powder.

[0071] (5) Take 2.0g of nano-sized pyrite powder obtained in step (4) and spread it evenly in a ceramic boat. Place it in a reduction furnace and heat it to 600℃ in a pure hydrogen atmosphere at a heating rate of 5℃ / min. Hold it for 30min and then continue heating to 950℃ at a heating rate of 1℃ / min. Hold it for 120min. Then switch to argon gas and cool it to room temperature in an argon atmosphere. Remove the rubber tube at the end of the tubular furnace from the water surface and slowly shut off the argon gas to obtain low-cost sulfide nano-zero valent iron (Py-SNZVI) synthesized from pyrite.

[0072] Example 3: A preparation process of low-cost sulfide nano-zero-valent iron synthesized from pyrite.

[0073] (1) Take 15g of pyrite powder, 1.5g of anhydrous FeCl3 (the mass of Fe in the anhydrous FeCl3 is 7.5% of the mass of Fe in the pyrite powder), 50g of zirconia grinding beads A, 50g of zirconia grinding beads B, 200g of zirconia grinding beads C, and 30mL of anhydrous ethanol and place them in a grinding jar. The anhydrous ethanol is a grinding aid. The diameter of the zirconia grinding beads A is 6.0mm, the diameter of the zirconia grinding beads B is 3.0mm, and the diameter of the zirconia grinding beads C is 2.0mm.

[0074] (2) The ball mill jar was then placed on a planetary ball mill for ball milling at a speed of 450 rpm for 24 hours. After the ball milling was completed, the pyrite powder was obtained by washing with water.

[0075] (3) The pyrite powder obtained in step (2) is dried at 60°C for 8 hours to obtain small-particle-size pyrite powder blocks.

[0076] (4) Grind the small-particle-size pyrite powder blocks obtained in step (3) with a mortar and pestle to obtain nano-sized pyrite powder.

[0077] (5) Take 2.0g of nano-sized pyrite powder obtained in step (4) and spread it evenly in a ceramic boat. Place it in a reduction furnace and heat it to the reduction temperature of 600℃ under a pure hydrogen atmosphere. The heating rate is 5℃ / min and it is held for 30min. Then continue to heat it to the reduction temperature of 950℃ at a heating rate of 1℃ / min and it is held for 120min. Then switch to argon gas and cool it to room temperature under an argon atmosphere. Take the rubber tube at the end of the tubular furnace out of the water and slowly turn off the argon gas to obtain low-cost sulfide nano-zero valent iron (Py-SNZVI) synthesized from pyrite.

[0078] Comparative laboratory process for preparing nano-zero valent iron sulfide using sodium borohydride liquid-phase reduction (Lab-SNZVI)

[0079] (1) Take 5.8 g of FeCl3 and add it to 200 mL of deionized water to dissolve it and obtain a ferric chloride solution;

[0080] (2) Take 0.22 g of sodium dithionite and 6.8 g of sodium borohydride, add them to 200 mL of deionized water and dissolve them to obtain a sulfur solution;

[0081] (3) Under a nitrogen atmosphere and with stirring at 300 rpm, the sulfur solution prepared in step (2) is added to the ferric chloride solution prepared in step (1) at a dropping rate of 10 mL / min and stirred for 10 minutes.

[0082] (4) After stirring, solid-liquid separation was carried out. The solid was washed three times with deionized water and dried under vacuum at 60 degrees Celsius for 8 hours to obtain a dry solid.

[0083] (5) Grind the dry solid obtained in step (4) into powder to obtain sulfide nano-zero valent iron prepared in the laboratory.

[0084] Application Example 1: Test Experiment on the Proportion of Zero-Valence Iron

[0085] Take 0.1g of the low-cost sulfide nano-zero-valent iron synthesized from pyrite as raw material, prepared in Examples 1 to 3, and place them in different sample bottles. Use a magnet to attract the Py-SNZVI powder to the top of the bottle wall. Add 10mL of concentrated hydrochloric acid solution to each bottle, being careful not to let the concentrated hydrochloric acid solution come into contact with the material. After sealing the sample bottle, remove the magnet and place the Py-SNZVI powder down to react with the concentrated hydrochloric acid solution. After the Py-SNZVI powder has reacted completely, measure the amount of headspace hydrogen in the sample bottle, making three copies. Calculate the zero-valent iron content in Py-SNZVI, and then divide it by the total iron content measured by ICP-OES to obtain the proportion of zero-valent iron to total iron. The calculation results are as follows: Figure 1 As shown.

[0086] from Figure 1 It can be seen that the proportion of zero-valent iron in the total iron of the low-cost sulfide nano-zero-valent iron synthesized from pyrite prepared in Examples 1 to 3 is all above 68%, which is close to or even exceeds that of laboratory-prepared sulfide nano-zero-valent iron (Lab-SNZVI). Moreover, the proportion of zero-valent iron in the total iron of Example 3 reaches 95.2%, indicating that the low-cost sulfide nano-zero-valent iron synthesized from pyrite prepared in Example 3 has the highest reduction rate.

[0087] Application Example 2: Characterization using Transmission Electron Microscopy (TEM) and Energy Dispersive X-ray Spectroscopy (EDS)

[0088] Since the low-cost sulfide nano-zero-valent iron prepared in Example 3 has the highest zero-valent iron content and the strongest activity, only the low-cost sulfide nano-zero-valent iron (Py-SNZVI) prepared in Example 3, as well as the low-cost sulfide nano-zero-valent iron prepared in Example 3, the ball-milled pyrite, and the directly reduced ball-milled pyrite, were characterized by transmission electron microscopy. The specific steps were as follows: the powder to be tested was completely dispersed by ultrasonication with anhydrous ethanol, dropped onto a silicon wafer, air-dried, sputtered with gold, and then characterized by transmission electron microscopy. The characterization results are as follows. Figures 2-5 As shown. Figure 2 Transmission electron microscopy and energy-dispersive X-ray spectroscopy characterization of pyrite after ball milling; Figure 3 Transmission electron microscopy and energy-dispersive X-ray spectroscopy characterization of directly reduced ball-milled pyrite; Figure 4Transmission electron microscopy and energy-dispersive X-ray spectroscopy characterization of low-cost sulfide nano-zero-valent iron synthesized from pyrite before reduction. Figure 5 The images show the transmission electron microscope (TEM) and energy-dispersive X-ray spectroscopy (EDX) characterization of the low-cost sulfide nano-zero-valent iron synthesized from pyrite as raw material in Example 3.

[0089] from Figure 2 and Figure 4 As can be seen, the ball-milled pyrite exhibits significant fragmentation, with particle size reduced to the nanometer scale, and the addition of FeCl3 has no impact on the morphology of the ball-milled material. (Comparison) Figure 2 and Figure 3 ( Figure 4 and Figure 5 It was found that after high-temperature reduction, the originally irregular nano-pyrite particles transformed into regular spherical nanoparticles, which may be related to the sintering and casting of iron particles under high-temperature conditions. Measurements of the energy-dispersive X-ray spectra of S and Fe in the particles revealed that after the addition of FeCl3, the distribution of S became more uniform, and there were no aggregated elemental S particles (such as...). Figure 3 (b) This may explain why the addition of FeCl3 increases the zero-valent iron content. In summary, this characterization demonstrates that the method provided by this invention can prepare spherical sulfide nanoparticles with uniform S distribution.

[0090] Application Example 3: Particle Size Distribution (D50) Test Experiment

[0091] The particle size distribution of low-cost sulfide nano-zero-valent iron synthesized from pyrite as raw material, prepared in Examples 1-3, was tested using a laser particle size analyzer. The specific steps were as follows: a small amount of material of equal mass was dispersed in anhydrous ethanol, sonicated for at least half an hour, and then diluted until the particles were uniformly distributed and invisible to the naked eye. The particle size was then analyzed using a laser particle size analyzer. The test results are as follows: Figure 6 As shown.

[0092] from Figure 6 It can be seen that the D50 of the materials prepared by this method can all reach below 250 nm, proving that the particle size of the prepared materials is in the nanoscale, which is comparable to that of SNZVI prepared in the laboratory. The main reason is that pyrite has high hardness (Mohs hardness 6-6.5) and low ductility, making it easier to break rather than stretch during ball milling. In addition, pyrite itself is non-magnetic, and the particles are not easy to agglomerate, which is more conducive to achieving and maintaining the nanoscale.

[0093] Application Example 4: X-ray Diffraction (XRD) Test Experiment

[0094] X-ray diffraction tests were performed on the low-cost sulfide nano-zero-valent iron synthesized from pyrite prepared in Examples 1-3, and the test results are as follows: Figure 7 As shown.

[0095] from Figure 7 It can be seen that the low-cost sulfide nano-zero-valent iron synthesized from pyrite prepared in Examples 1-3 all exhibited Fe. 0 The presence of characteristic peaks, especially the main characteristic peaks, indicates that the powder has been effectively reduced.

[0096] Application Example 5: Cost reduction in the preparation of low-cost sulfide nano-zero-valent iron

[0097] The low-cost sulfide nano-zero-valent iron synthesized from pyrite in Example 3 and the sulfide nano-zero-valent iron (SNZVI) prepared by laboratory liquid-phase reduction method in the comparative example were compared respectively. NaBH4 Nano-zero valent iron (NZVI) prepared by laboratory liquid-phase reduction method NaBH4 The preparation cost was calculated by listing the specific preparation steps and categorizing the items into raw material costs and processing costs according to their intended use. Raw material costs include chemical reagents and gases used in the preparation process, while processing costs include energy consumption and water usage. The same unit price was used for all items; for example, the "energy consumption" item was calculated using the average 1-10 kV electricity price for large industrial use in Zhejiang Province in 2023 (RMB 0.7169 / kWh). The calculation results are as follows: Figure 8 As shown. And based on different yields, the price changes of the low-cost sulfide nano-zero-valent iron synthesized from pyrite in Example 3 under different yield conditions are calculated as follows: Figure 9 .

[0098] Application Example 6: Simulated TCE Degradation Experiment in Groundwater

[0099] The degradation of TCE (trichloroethene) in simulated groundwater was carried out using low-cost sulfide nano-zero-valent iron synthesized from pyrite prepared in Examples 1-3. The preparation steps for simulating TCE-contaminated groundwater were as follows: a saturated TCE solution was diluted 100 times to obtain a TCE concentration of 70 μmol / L. Nitrogen was purged for 25 min to remove dissolved oxygen and simulate the groundwater environment. 100 mL of simulated TCE-contaminated groundwater was added to the reactor, followed by 0.1 g of the low-cost sulfide nano-zero-valent iron synthesized from pyrite prepared in Examples 1-3. The headspace was then purged with nitrogen for 10 s, and the reactor lid was quickly closed. Two reactors were prepared for parallel reactions. The reactor was placed in a 50 rpm inverted reactor for the reaction. 0.1 mL of headspace gas was extracted every 24 hours, and the TCE concentration and degradation products were determined using gas chromatography. The results are as follows: Figure 10 As shown. The reaction rate was calculated using the total iron content normalized, and the results are as follows. Figure 11 As shown.

[0100] from Figure 10 It can be seen that after 12 days of reaction, the low-cost sulfide nano-zero-valent iron synthesized from pyrite in Example 3 had completely degraded TCE. The reaction rate of the low-cost sulfide nano-zero-valent iron synthesized from pyrite in Examples 1-3 gradually increased. After normalization of total iron, the TCE degradation rate was basically close to that of SNZVI reduced by sodium borohydride in the liquid phase, proving that this preparation method has great potential and can effectively degrade TCE in groundwater, showing great application prospects.

[0101] Application Example 7: Simulated FF Degradation Experiment in Groundwater

[0102] The degradation of FF (Florfenicol) in simulated groundwater was carried out using low-cost sulfide nano-zero-valent iron synthesized from pyrite prepared in Examples 1-3. The preparation steps for simulating FF-contaminated groundwater were as follows: a solution with an FF concentration of 0.28 mmol / L was prepared, and dissolved oxygen was removed by nitrogen purging for 25 min to simulate the groundwater environment. 100 mL of simulated FF-contaminated groundwater was added to the reactor, followed by the addition of 0.1 g of the low-cost sulfide nano-zero-valent iron synthesized from pyrite prepared in Examples 1-3. The headspace was then purged with nitrogen for 10 s, and the reactor lid was quickly closed. Two replicates were performed. The reactor was placed in a 50 rpm inverted reactor for the reaction. Samples were taken at appropriate intervals during the 8-hour reaction time, and the FF concentration and degradation products were determined by liquid chromatography. The results are shown below. Figure 12 As shown. The reaction rate was calculated using the total iron content normalized, and the results are as follows. Figure 13 As shown.

[0103] from Figure 12 It can be seen that, after 8 hours of reaction, the low-cost sulfide nano-zero-valent iron synthesized from pyrite in Example 3 essentially completely removed FF from the simulated groundwater. Figure 13 As shown, the reaction rate of low-cost sulfide nano-zero-valent iron synthesized from pyrite as raw material prepared in Examples 1-3 gradually increases. After the total iron is normalized, the FF removal rate is basically close to that of SNZVI reduced by sodium borohydride in the liquid phase. This proves that the preparation method has great potential and can effectively remove FF from groundwater, and has great application prospects.

[0104] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A low-cost sulfide nano-zero-valent iron synthesized from pyrite, characterized in that, The low-cost sulfide nano-zero-valent iron synthesized from pyrite is prepared by the following method: (1) Pyrite powder, anhydrous FeCl3, a combination of zirconia grinding beads, and anhydrous ethanol are placed in a grinding jar. The zirconia grinding bead combination consists of zirconia grinding beads A, zirconia grinding beads B, and zirconia grinding beads C. The diameter of zirconia grinding beads A is 6.0-6.2 mm, the diameter of zirconia grinding beads B is 3.0-3.2 mm, and the diameter of zirconia grinding beads C is 2.0-2.2 mm. The mass ratio of zirconia grinding beads A, zirconia grinding beads B, and zirconia grinding beads C is 1:1:

4. The mass ratio of pyrite powder to the zirconia grinding bead combination is 1:

20. The mass ratio of pyrite powder to the volume of anhydrous ethanol is 1 g:1-3 mL. The mass of Fe in the anhydrous FeCl3 is 0%-10% of the mass of Fe in the pyrite powder. (2) The ball mill jar is then placed on a planetary ball mill for ball milling. After ball milling, the pyrite powder is washed with water to obtain the ground pyrite powder. (3) The ground pyrite powder obtained in step (2) is dried to obtain small-particle-size pyrite powder blocks. (4) The small-particle-size pyrite powder blocks obtained in step (3) are ground with a mortar to obtain nano-sized pyrite powder. (5) The pyrite powder obtained in step (4) is spread evenly in a porcelain boat and placed in a reduction furnace. Under a pure hydrogen atmosphere, the temperature is raised to 500-650℃ at a rate of 5-10℃ / min and held for 10-30min. Then the temperature is raised to 900-1100℃ at a rate of 0.5-2℃ / min and held for 60-180min. Then argon gas is introduced and cooled to room temperature under an argon atmosphere to obtain low-cost sulfide nano-zero-valent iron synthesized from pyrite.

2. The low-cost sulfide nano-zero-valent iron synthesized from pyrite as raw material according to claim 1, characterized in that, The pyrite powder has a particle diameter of 40–45 μm.

3. The low-cost sulfide nano-zero-valent iron synthesized from pyrite as raw material according to claim 1, characterized in that, The optimal mass ratio of Fe in the anhydrous FeCl3 to Fe in the pyrite powder is 0.075:

1.

4. The low-cost sulfide nano-zero-valent iron synthesized from pyrite as a raw material according to claim 1, characterized in that, In step (2), the ball milling parameters are set to 400-450 rpm for 20-24 hours.

5. The application of the low-cost sulfide nano-zero-valent iron synthesized from pyrite as described in claim 1 for the degradation of TCE in TCE-contaminated groundwater.

6. The application according to claim 5, characterized in that, Specifically, the following steps are included: (a1) Using a TCE solution with a concentration of 50-80 μmol / L, TCE-contaminated groundwater was simulated under anaerobic conditions; (a2) 0.1 g of low-cost sulfide nano-zero-valent iron synthesized from pyrite was placed into 100 mL of simulated TCE-contaminated groundwater, and nitrogen was blown into the headspace of the container; (a3) ​​The container was placed on a rotating device at room temperature and rotated at 50 rpm for 7-10 days to achieve the degradation of TCE in the simulated TCE-contaminated groundwater.

7. The application of the low-cost sulfide nano-zero-valent iron synthesized from pyrite as described in claim 1 for the degradation of florfenicol in groundwater contaminated with florfenicol.

8. The application according to claim 7, characterized in that, Specifically, the following steps are included: (a1) Prepare a 0.028–0.28 mmol / L florfenicol solution and simulate florfenicol-contaminated groundwater under anaerobic conditions; (a2) Add 0.1 g of low-cost sulfide nano-zero-valent iron synthesized from pyrite to 100 mL of simulated florfenicol-contaminated groundwater and purge the container with nitrogen from the headspace; (a3) ​​Place the container on a turner at room temperature and rotate it at 50 rpm for 8–10 h to degrade florfenicol in the simulated florfenicol-contaminated groundwater.

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