A method for preparing pyrite / graphite composite material by using ball milling method and application of the pyrite / graphite composite material in photocatalytic HMF conversion
Pyrite/graphite composite materials were prepared by mechanical ball milling, which destroyed the passivation layer of pyrite and formed a microporous structure. Combined with the electrical conductivity of graphite, this method solved the problems of insufficient catalytic activity of pyrite and waste of graphite resources, and achieved a highly efficient photocatalytic reaction.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHANGZHOU UNIV
- Filing Date
- 2026-04-22
- Publication Date
- 2026-07-03
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Abstract
Description
Technical Field
[0001] This invention relates to nanomaterial synthesis and biomass waste conversion technology, specifically providing a method for preparing pyrite / graphite composite materials based on mechanical ball milling and its application in photocatalytic HMF conversion. Background Technology
[0002] With the continued depletion of fossil fuels, greenhouse gas emissions are surging and resource depletion is becoming increasingly serious. Developing renewable and sustainable energy has become a global focus. Biomass, as an abundant renewable resource, plays a crucial role in achieving carbon neutrality and a circular economy through its high-value conversion. 5-Hydroxymethylfurfural (HMF), as an important biomass platform molecule, can be transformed into high-value-added chemicals through reactions such as oxidation and hydrogenation, serving as a key bridge connecting biomass and fossil resources.
[0003] Natural mineral materials have attracted widespread attention in the field of photocatalysis due to their abundant reserves, low cost, and numerous surface active sites. Pyrite (FeS2), a typical pyrite, possesses advantages such as narrow band gap, high light absorption, and low cost; however, its surface often has an oxide passivation layer, limiting its catalytic activity. Therefore, exposing its active sites through physical or chemical means is key to improving its performance. On the other hand, graphite, the negative electrode material in retired power batteries, has a high specific surface area and excellent electron migration ability, and its layered structure is conducive to the separation of photogenerated electron-hole pairs. Combining graphite with pyrite can not only suppress carrier recombination but also realize the resource utilization of waste graphite, embodying the green concept of treating waste with waste. Mechanical ball milling, as a green and efficient solid-phase synthesis technology, does not require the use of harmful reagents and can effectively reduce particle size, destroy the surface passivation layer, and promote material activation and composite. Currently, there are no reports on the preparation of pyrite / waste graphite composite materials using mechanical ball milling. Summary of the Invention
[0004] Based on the aforementioned technical background, this invention provides a method for preparing a composite material using pyrite, a natural mineral material, and waste battery negative electrode graphite as precursors. This invention uses pyrite and waste battery negative electrode graphite in different mass ratios as raw materials, resulting in low raw material costs and high yields. The catalyst is synthesized by ball milling the precursor materials using mechanical ball milling, making the preparation method simple.
[0005] To achieve the objectives of this invention, the following technical solution is adopted:
[0006] A method for preparing pyrite / graphite composite materials using mechanical ball milling specifically includes the following steps:
[0007] (1) Add pyrite and graphite, and KOH in a mass ratio of (1-5):100 relative to pyrite, into a ball mill jar, wherein the mass ratio of graphite to pyrite is (1-20):100.
[0008] (2) The sample prepared in (1) is placed in a mechanical ball mill and pyrite / graphite composite material is synthesized by ball milling in an air atmosphere. The revolution speed of the ball milling process in the mechanical ball mill is 300-600 rpm and the ball milling time is 3-6 h.
[0009] (3) The pyrite / graphite composite material is scraped out of the ball mill jar, passed through an 80-120 mesh sieve, and then stored for later use.
[0010] (4) Subsequently, the ball-milled composite material was calcined in a tube furnace at 400~500℃ for 2~5h under nitrogen atmosphere protection, then ground and stored for later use.
[0011] Furthermore, the preferred mass ratio of graphite to pyrite is (5-15):100.
[0012] Furthermore, the KOH mass ratio relative to pyrite is preferably (3-5):100.
[0013] Furthermore, the grinding beads are zirconium oxide. The materials were prepared using a planetary ball mill. Large balls with a diameter of approximately 10 mm and small balls with a diameter of approximately 3 mm were mixed, with a mass ratio of large balls to small balls of 1:1 to 4:1. In all experiments, the ball-to-material mass ratio was 90 to 95:1.
[0014] The pyrite / graphite composite material prepared by the above method was applied to the photocatalytic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxaldehyde (DFF).
[0015] Compared with existing technologies, the advantages of this invention are:
[0016] This invention prepares pyrite / graphite composite materials through ball milling. While ensuring uniform mixing of the two materials, ball milling also minimizes their particle size. Furthermore, ball milling disrupts the naturally occurring passivation layer of pyrite, exposing active sites and improving its photocatalytic performance. KOH can etch graphite, forming a microporous / mesoporous structure, increasing the specific surface area and providing more anchoring sites for pyrite. It can also synergistically with ball milling to disrupt the oxide layer on the pyrite surface, exposing fresh active surfaces and promoting tight interfacial bonding with the carbon substrate. During ball milling, heteroatoms (K) can be introduced, and potassium elements can be embedded into the carbon framework, introducing structural defects, regulating the electronic structure, and optimizing catalytic activity.
[0017] This invention fully utilizes the excellent conductivity of graphite, the negative electrode material of waste batteries, and applies it to the separation of photogenerated electrons and holes in pyrite, organically combining the two. This solves the problems of high recombination rates of photogenerated carriers due to the short band gap of pyrite, and also addresses the waste of waste graphite resources and environmental pollution. Furthermore, the heat energy generated by graphite absorbing light under illumination can also help couple pyrite to overcome the necessary energy barrier in the photocatalytic process, enhancing the number and energy of effective carriers in the 5-HMF oxidation reaction, thereby accelerating the catalytic reaction and increasing the yield of DFF. Attached Figure Description
[0018] Figure 1 XRD patterns of pyrite / graphite composite materials prepared in Examples 1-5 and comparative Examples 1-2;
[0019] Figure 2 TEM image of the pyrite / graphite composite material sample prepared in Example 4;
[0020] Figure 3 FT-IR images of pyrite / graphite composite materials prepared in Examples 1-5 and comparative Examples 1-2;
[0021] Figure 4 The HMF conversion rate and DFF production rate are plots of the pyrite / graphite composite materials prepared in Examples 1-5 and the photocatalytic HMF to DFF conversion in Comparative Examples 1-4. Detailed Implementation
[0022] Unless otherwise specified, all mechanical ball milling experiments in the following examples and comparative examples were conducted using a planetary ball mill. The milling media were zirconia balls, and a mixture of large and small balls was used to improve grinding efficiency. The large balls had a diameter of 10 mm, and the small balls had a diameter of 3 mm; the mass ratio of large to small balls was 3:1. In all experiments, the ball-to-material mass ratio (the ratio of the total mass of the milling media to the total mass of the raw material powder) was controlled at 95:1.
[0023] Example 1:
[0024] (1) Take 100 g of pyrite, 1 g of graphite and 1 g of KOH as precursors and add them to the ball mill jar respectively;
[0025] (2) Place the sample weighed in (1) into a mechanical ball milling device, set the ball milling revolution speed to 600 rpm, and the ball milling time to 6 h. In an air atmosphere, synthesize the composite material by ball milling. After ball milling, pass it through a 100-mesh sieve.
[0026] (3) Subsequently, the ball-milled composite material was calcined in a tube furnace at 500°C for 2 hours under nitrogen atmosphere protection, then ground and stored for later use to obtain pyrite / graphite composite material.
[0027] The XRD pattern of the pyrite / graphite composite material prepared in Example 1 is shown below. Figure 1 As shown, the peaks of the composite material correspond one-to-one with the FeS2 card (JCPDS: 99-0087) and the graphite card (JCPDS: 41-1487); the (002) diffraction peak of graphite shifts to a lower angle and the peak shape is significantly broadened, indicating that the insertion of potassium ions increases the carbon interlayer spacing and introduces lattice distortion.
[0028] FT-IR Figure 3 As shown, the prepared material exhibits corresponding target groups (Fe-S and SS bonds in pyrite), confirming the formation of the target composite structure.
[0029] Photocatalytic experiments on the oxidation of HMF were conducted in a 100 mL photochemical reactor. First, 40 mL of deionized water and 0.1 g of pyrite / graphite composite material were added to a photochemical autoclave. Then, 0.05 g of HMF was added to the reactor and stirred magnetically until completely dissolved and thoroughly mixed with the materials. A 300 W xenon lamp was used as the light source, and the reaction solution was exposed to light for 5 hours through a transparent window at the top of the visible light reactor. The extracted reaction liquid was analyzed using liquid chromatography.
[0030] The HMF conversion rate and DFF yield of the pyrite / graphite composite material prepared in Example 1 are shown in the figure below. Figure 4 As shown, the HMF conversion rate was 39.8%; the DFF production rate was 97.41 μmol·g⁻¹. -1 ·h -1 .
[0031] Example 2:
[0032] (1) Take 100g of pyrite, 5g of graphite and 2g of KOH as precursors and add them to the ball mill jar respectively;
[0033] (2) Place the sample weighed in (1) into a mechanical ball milling device, set the ball milling revolution speed to 300 rpm, and the ball milling time to 5 h. In an air atmosphere, synthesize the composite material by ball milling. After ball milling, pass it through a 100-mesh sieve.
[0034] (3) Subsequently, the ball-milled composite material was calcined in a tube furnace at 400°C for 2 hours under nitrogen atmosphere protection, then ground and stored for later use to prepare pyrite / graphite composite material.
[0035] The XRD pattern of the pyrite / graphite composite material prepared in Example 2 is as follows: Figure 1As shown, the peaks of the composite material correspond one-to-one with the FeS2 card (JCPDS: 99-0087) and the graphite card (JCPDS: 41-1487); FT-IR Figure 3 As shown, the prepared material has corresponding target groups present.
[0036] The HMF photocatalytic oxidation experiment process is as described in Example 1. The HMF conversion rate and DFF yield graphs of the pyrite / graphite composite materials prepared in Example 2 are shown below. Figure 4 As shown, the HMF conversion rate was 49.4%; the DFF production rate was 185.75 μmol·g⁻¹. -1 ·h -1 .
[0037] Example 3:
[0038] (1) Take 100g of pyrite, 10g of graphite and 3g of KOH, and add them into the ball mill jar respectively;
[0039] (2) Place the sample weighed in (1) into a mechanical ball milling device, set the ball milling speed to 400 rpm and the ball milling time to 4 h, and synthesize the composite material by ball milling in an air atmosphere. After ball milling, pass it through a 100-mesh sieve.
[0040] (3) Subsequently, the ball-milled composite material was calcined in a tube furnace at 500°C for 3 hours under nitrogen atmosphere protection, then ground and stored for later use to obtain pyrite / graphite composite material.
[0041] The XRD pattern of the pyrite / graphite composite material prepared in Example 3 is as follows: Figure 1 As shown, the peaks of the composite material correspond one-to-one with the FeS2 card (JCPDS: 99-0087) and the graphite card (JCPDS: 41-1487); FT-IR Figure 3 As shown, the prepared material has corresponding target groups present.
[0042] The HMF photocatalytic oxidation experiment process is as described in Example 1. The HMF conversion rate and DFF yield graphs of the pyrite / graphite composite materials prepared in Example 3 are shown in the figures. Figure 4 As shown, the HMF conversion rate was 61.1%; the DFF production rate was 271.53 μmol·g⁻¹. -1 ·h -1 .
[0043] Example 4:
[0044] (1) Take 100g of pyrite, 15g of graphite and 4g of KOH, and add them into the ball mill jar respectively;
[0045] (2) Place the sample weighed in (1) into a mechanical ball milling device, set the ball milling revolution speed to 500 rpm, and the ball milling time to 3 h. In an air atmosphere, synthesize the composite material by ball milling. After ball milling, pass it through a 100-mesh sieve.
[0046] (3) Subsequently, the ball-milled composite material was calcined in a tube furnace at 500°C for 2 hours under nitrogen atmosphere protection, then ground and stored for later use to obtain pyrite / graphite composite material.
[0047] The XRD pattern of the pyrite / graphite composite material prepared in Example 4 is as follows: Figure 1 As shown, during ball milling, the mechanical force causes the graphite sheets to break continuously, reducing the degree of graphitization. The (002) crystal plane is extensively damaged, the grain size becomes smaller and finer, resulting in broadened diffraction peaks and decreased intensity. Furthermore, ball milling tightly bonds graphite and pyrite, causing the orientation of the graphite sheets to become random, disrupting the original preferred orientation arrangement, leading to a relative decrease in the intensity of the (002) peak. In XRD testing, the X-ray mass absorption coefficient of pyrite is much higher than that of graphite. When the graphite content increases, although the proportion of pyrite as a heavy matrix in the composite material decreases relatively, its strong absorption effect on X-rays remains significant. That is, pyrite strongly absorbs X-rays, resulting in a weakening of the incident light intensity reaching the graphite crystal plane, thereby reducing the diffraction signal of graphite.
[0048] TEM image Figure 2 As shown, the 2D-to-2D stacked morphology achieves a synergistic effect of large-area interfacial contact, high active site exposure, and structural stability, which is the key structural basis for the excellent catalytic performance of the composite material. This morphology is usually due to the mechanochemical effect during ball milling and the KOH-assisted interfacial regulation; FT-IR Figure 3 As shown, the prepared material has corresponding target groups present.
[0049] The HMF photocatalytic oxidation experiment process is as described in Example 1. The HMF conversion rate and DFF yield graphs of the pyrite / graphite composite materials prepared in Example 4 are shown below. Figure 4 As shown, the HMF conversion rate was 82.7%; the DFF production rate was 320.67 μmol·g⁻¹. -1 ·h -1 .
[0050] Example 4-1:
[0051] Compared with Example 4, the only difference was that 100g of pyrite, 5g of graphite, and 4g of KOH were added to the ball mill jar, and the other conditions were the same as in Example 4. The HMF conversion rate was 81.6% and the DFF production rate was 311.62 μmol·g⁻¹. -1 ·h -1 .
[0052] Example 4-2:
[0053] Compared with Example 4, the only difference is that 100g of pyrite, 20g of graphite, and 4g of KOH were added to the ball mill jar, and the other conditions were the same as in Example 4. The HMF conversion rate was 75.8% and the DFF production rate was 291.64 μmol·g⁻¹. -1 ·h -1 .
[0054] Example 5:
[0055] (1) Take 100g of pyrite, 20g of graphite and 5g of KOH, and add them into the ball mill jar respectively;
[0056] (2) The sample weighed in (1) was placed in a mechanical ball mill, the ball mill revolution speed was set to 600 rpm, the ball milling time was 3 h, and the pyrite / graphite composite material was synthesized by ball milling in an air atmosphere.
[0057] (3) Subsequently, the ball-milled composite material was calcined in a tube furnace at 500°C for 5 hours under nitrogen atmosphere protection, then ground and stored for later use.
[0058] The XRD pattern of the composite material prepared in Example 5 is as follows: Figure 1 As shown, the peaks of the composite material correspond to those on the card (JCPDS: 99-0087), indicating successful material synthesis; FT-IR Figure 3 As shown, the prepared material has corresponding target groups present.
[0059] The HMF photocatalytic oxidation experiment process is as described in Example 1. The HMF conversion rate and DFF yield of the pyrite / graphite composite material are shown in the figure below. Figure 4 As shown, the HMF conversion rate was 45.4%; the DFF production rate was 268.24 μmol·g⁻¹. -1 ·h -1 .
[0060] Example 6:
[0061] Example 6 differs from Example 5 in that: 100g of pyrite, 5g of graphite, and 3g of KOH were added to a ball mill jar, while the other conditions remained the same as in Example 5. The HMF conversion rate was 42.6%, and the DFF production rate was 308.52 μmol·g⁻¹. -1 ·h -1 .
[0062] Example 7:
[0063] Example 7 differs from Example 5 in that: 100g of pyrite, 5g of graphite, and 2g of KOH were added to a ball mill jar, while the other conditions remained the same as in Example 7. The HMF conversion rate was 35.6%, and the DFF production rate was 216.63 μmol·g⁻¹. -1 ·h -1 .
[0064] Comparative Example 1:
[0065] (1) Take 1g of pyrite and 0.04g of KOH as precursors and add them to the ball mill jar. Do not add graphite.
[0066] (2) The sample weighed in (1) was placed in a mechanical ball milling device, the ball milling speed was set to 600 rpm, the ball milling time was 6 h, and the ball milling pyrite material was synthesized by ball milling in an air atmosphere.
[0067] (3) Subsequently, the ball-milled material was calcined in a tube furnace at 500°C for 2 hours under nitrogen atmosphere protection, then ground and stored for later use.
[0068] The XRD pattern of the prepared material is as follows: Figure 1 As shown, the peaks of the material correspond to the FeS2 card (JCPDS: 99-0087), but the peak intensities are significantly lower than those in Example 1, indicating that some crystal planes of the material have not been enhanced; FT-IR Figure 3 As shown.
[0069] The HMF photocatalytic oxidation experiment in Comparative Example 1 was as described in Example 1. Because no graphite was added to assist in the separation of photogenerated carriers, the HMF conversion rate and DFF yield of the ball-milled pyrite material were lower. Figure 4 As shown, the HMF conversion rate was only 10.5%; the DFF production rate was only 95.42 μmol·g⁻¹. -1 ·h -1 .
[0070] Comparative Example 2:
[0071] (1) Take 1g of graphite and 0.27g of KOH as precursors and add them to the ball mill jar. Do not add pyrite.
[0072] (2) Place the sample weighed in (1) into a mechanical ball milling device, set the ball milling revolution speed to 600 rpm, and the ball milling time to 6 h, and synthesize ball milled graphite material by ball milling in an air atmosphere;
[0073] (3) Subsequently, the ball-milled material was calcined in a tube furnace at 500°C for 2 hours under nitrogen atmosphere protection, then ground and stored for later use.
[0074] The XRD pattern of the material prepared in Comparative Example 2 is as follows: Figure 1 As shown, the peaks of the material correspond to those on the graphite card (JCPDS: 41-1487), but compared with the examples, no characteristic peaks of pyrite appeared, and no target product appeared in the photocatalytic experiment, indicating that the material has no catalytic effect; FT-IR Figure 3 As shown, the prepared material did not contain the corresponding target functional group.
[0075] The HMF photocatalytic oxidation experiment was conducted as described in Example 1. Due to the absence of pyrite, the HMF conversion rate of the ball-milled graphite composite material was low. Figure 4 As shown, no product DFF was generated.
[0076] Comparative Example 3:
[0077] (1) Take 100g of pyrite, 15g of graphite and 4g of KOH as precursors and obtain pyrite / graphite composite material by direct physical dry mixing.
[0078] (2) Subsequently, the dry-mixed composite material was calcined in a tube furnace at 500°C for 2 hours under nitrogen atmosphere protection, then ground and stored for later use.
[0079] The photocatalytic oxidation results of HMF showed that the HMF conversion rate was only 22.7% and the DFF production rate was only 60.56 μmol·g. -1 ·h -1 .
[0080] Comparative Example 4:
[0081] (1) Take 100g of pyrite, 15g of graphite and 4g of KOH, and add them into the ball mill jar respectively;
[0082] (2) The sample weighed in (1) was placed in a mechanical ball mill, the ball milling speed was set to 500 rpm, the ball milling time was 3 h, and the pyrite / graphite composite material was synthesized by ball milling in an air atmosphere.
[0083] After ball milling, the material was not subjected to calcination under an inert atmosphere and was directly stored for later use.
[0084] The results of the photocatalytic oxidation of HMF in Comparative Example 4 showed that the HMF conversion rate was only 15.7% and the DFF production rate was only 50.23 μmol·g⁻¹. -1 ·h -1 .
[0085] Comparative Example 5:
[0086] Compared with Example 4, the difference is that KOH is not added during the preparation process, while the rest of the operation is the same as in Example 4.
[0087] The obtained material was used in the photocatalytic oxidation of HMF, and the experimental procedure was as described in Example 1. The experimental results showed that the HMF conversion rate was 38.5%; the DFF production rate was only 150.18 μmol·g⁻¹. -1 ·h -1 .
[0088] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.
Claims
1. A method for preparing a pyrite / graphite composite material using a ball milling method, characterized by, Includes the following steps: (1) Add pyrite, graphite and potassium hydroxide into a ball mill jar, wherein the mass ratio of graphite to pyrite is (1-20):100 and the mass ratio of potassium hydroxide to pyrite is (1-5):100; (2) The mixture in step (1) is ball-milled in air atmosphere to obtain the ball-milled product; (3) The ball-milled product is sieved; (4) The product after step (3) is calcined at 400-500°C for 2-5 hours under an inert atmosphere to obtain the pyrite / graphite composite material.
2. The method for preparing pyrite / graphite composite material using a ball milling method according to claim 1, characterized by: In step (1), the mass ratio of graphite to pyrite is (5-15):
100. 3.The method for preparing pyrite / graphite composite material using a ball milling method according to claim 1, characterized in that: In step (2), the ball milling speed is 300-600 rpm and the ball milling time is 3-6 h. 4.The method for preparing pyrite / graphite composite material using a ball milling method according to claim 1, characterized in that: In step (4), the calcination temperature is 500℃ and the calcination time is 2h.
5. A pyrite / graphite composite material, characterized by, The composite material is prepared by the method described in any one of claims 1-4.
6. The application of the pyrite / graphite composite material according to claim 5 in the photocatalytic oxidation of 5-hydroxymethylfurfural.
7. Use according to claim 6, characterized in that: The product of the photocatalytic oxidation of 5-hydroxymethylfurfural is 2,5-furandicarboxaldehyde.