Preparation method and application of shell biochar-micron zero-valent iron-calcium polysulfide composite ball-milling material

Abstract

The invention discloses a preparation method and application of a shell biochar-micron zero-valent iron-calcium polysulfide composite ball-milling material, and relates to the technical field of preparation of composite ball-milling materials. The purpose of the invention is to solve the problem of poor Pb removal efficiency caused by easy oxidation and easy agglomeration of zero-valent iron when the zero-valent iron is used for removing heavy metal Pb in a water body. The method comprises the following steps: uniformly mixing pretreated shell biochar, micron zero-valent iron and calcium polysulfide, transferring into a stainless steel tank of a ball mill, adding three zirconium oxide balls with different particle sizes into the stainless steel tank of the ball mill, uniformly mixing, carrying out ball milling, taking out a material in the stainless steel tank of the ball mill after ball milling is finished, and sieving after grinding is finished, so as to obtain the zirconium oxide-based composite material. The shell biochar-micron zero-valent iron-calcium polysulfide composite ball-milling material is obtained. According to the preparation method and application of the shell biochar-micron zero-valent iron-calcium polysulfide composite ball-milling material, the shell biochar-micron zero-valent iron-calcium polysulfide composite ball-milling material can be obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of composite ball milling material preparation, and in particular to a preparation method and application of a shell biochar-micron zero-valent iron-calcium polysulfide composite ball milling material. Background Art

[0002] Under the combined influence of natural factors and human activities, heavy metal pollution in the environment is becoming increasingly serious, not only damaging the ecological environment but also posing a serious threat to human production and life. Pb, in particular, is known for its long-term accumulation, migration and transformation, and bioaccumulation. These characteristics make Pb pollution not only a long-term threat to the environment but also impacts human health through various pathways, particularly affecting children and pregnant women. Industrial wastewater is a major source of Pb contamination in water bodies. Industrial processes such as smelting and battery manufacturing generate large amounts of Pb-containing wastewater. The use of Pb-containing pesticides and fertilizers in agricultural activities, as well as wastewater irrigation, also contribute to increased Pb levels in water bodies. Furthermore, Pb in domestic wastewater primarily originates from daily necessities such as cosmetics, detergents, and hair dyes, as well as food containers and tableware. Furthermore, Pb is difficult to degrade in aquatic environments and ultimately persists in one or more forms for long periods, posing a potentially permanent threat. Therefore, comprehensive measures to control and prevent Pb pollution are necessary and urgent.

[0003] The principle of adsorption-based removal of Pb(II) from water primarily involves adsorbing Pb(II) ions in wastewater onto the adsorbent surface through surface adsorption, surface deposition, ion exchange, or electrostatic attraction, thereby purifying the water. Adsorption offers the advantages of low cost, high efficiency, and simple operation. The selection and performance of the adsorbent significantly influence the removal effect. Micronized zero-valent iron, as an iron-based material, is effective for removing Pb(II). However, its inherent susceptibility to oxidation and aggregation limits further removal of Pb(II). Therefore, it is necessary to modify micronized zero-valent iron to achieve even better performance. Summary of the Invention

[0004] The purpose of the present invention is to solve the problem of poor efficiency in removing heavy metal Pb in water due to its easy oxidation and agglomeration when zero-valent iron is used to remove heavy metal Pb, and to provide a preparation method and application of shell biochar-micron zero-valent iron-calcium polysulfide composite ball-milled material.

[0005] A method for preparing a shell biochar-micron zero-valent iron-calcium polysulfide composite ball-milled material is carried out according to the following steps: Step S1, pre-treatment of shell biochar: The shell biomass is crushed and sieved using a crusher, and then pyrolyzed using a tubular furnace to obtain pre-treated shell biochar; Step S2: preparing shell biochar-micronized zero-valent iron-calcium polysulfide composite ball-milled material: The pretreated shell biochar, micron zero-valent iron and calcium polysulfide obtained in step S1 are mixed evenly and then transferred to a stainless steel tank of a ball mill. Three zirconium oxide balls with different particle sizes are added to the stainless steel tank of the ball mill, mixed evenly and then ball milled. After the ball milling is completed, the material in the stainless steel tank of the ball mill is taken out and sieved to obtain a shell biochar-micron zero-valent iron-calcium polysulfide composite ball-milled material. The mass ratio of the pretreated shell biochar, micron zero-valent iron and calcium polysulfide is 1: (3.35~16.5):10.

[0006] An application of a shell biochar-micron zero-valent iron-calcium polysulfide composite ball milling material, and the application of the shell biochar-micron zero-valent iron-calcium polysulfide composite ball milling material in passivating heavy metals lead, cadmium and zinc and improving acidic soil.

[0007] Principle of the present invention: First, because coconut shell biochar has its own adsorption capacity, it can adsorb and remove some Pb(II); micron zero-valent iron contains abundant electrons, which can transfer electrons with Pb(II), thereby reducing the bioavailability of Pb(II); the calcium ions contained in calcium polysulfide can undergo ion exchange with Pb(II), and sulfur can react with zero-valent iron to form an iron sulfide shell on the surface, effectively preventing zero-valent iron from being passivated due to contact with air and reducing its performance. At the same time, coconut shell biochar is used to modify the material, and its rich surface pore structure can disperse micron zero-valent iron in these structures. In addition, its rich surface functional groups can also have a certain removal effect on Pb(II). This solves the problem that micron zero-valent iron is easily oxidized and easily agglomerated, and also provides a secondary use for agricultural and forestry waste, which has certain environmental benefits. The composite material of the present invention is prepared by ball milling, which can effectively fuse and load the three materials of coconut shell biochar / micron zero-valent iron / calcium polysulfide, and can effectively improve the adsorption performance of the material.

[0008] Beneficial effects of the present invention: 1. The present invention prepares coconut shell biochar / micron zero-valent iron / calcium polysulfide composite ball-milled materials by ball milling to repair heavy metal Pb(II) in water bodies. It has the advantages of simple synthesis, good repair effect and green environmental protection. Its main mechanism of action includes: (1) ion exchange between Pb(II) and protons on oxygen-containing functional groups (carboxyl, hydroxyl, etc.) of coconut shell biochar / micron zero-valent iron / calcium polysulfide composite ball-milled materials enhances the adsorption of Pb(II); (2) coconut shell biochar / micron zero-valent iron / calcium polysulfide composite ball-milled materials also have a certain pore structure, and Pb(II) can enter the pores by diffusion and be fixed; (3) coconut shell biochar / micron zero-valent iron / calcium polysulfide composite ball-milled materials are rich in Ca2+ , which can undergo ion exchange with Pb(II) in water and remove Pb(II); (4) The micron zero-valent iron in the coconut shell biochar / micron zero-valent iron / calcium polysulfide composite ball-milled material can effectively remove Pb(II).

[0009] Compared with other material modification technologies, ball milling offers a simple, cost-effective, and efficient modification method. Ball milling combines zero-valent iron with calcium polysulfide and loads it onto biochar, effectively addressing the issues of surface oxidation and agglomeration of zero-valent iron. The combined material effectively removes Pb(II) from water. Furthermore, ball milling allows for large-scale production, making it suitable for agricultural land remediation.

[0010] 3. The present invention prepares coconut shell biochar / micron zero-valent iron / calcium polysulfide composite ball-milled materials through ball milling technology, explores the removal performance of coconut shell biochar / micron zero-valent iron / calcium polysulfide on Pb(II) in water, and analyzes its related action mechanism.

[0011] The present invention can obtain a preparation method and application of a shell biochar-micron zero-valent iron-calcium polysulfide composite ball milling material. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 A scanning electron microscope image of a coconut shell biochar-micron zero-valent iron-calcium polysulfide composite ball-milled material in Example 1; Figure 2 : represents an X-ray diffraction pattern of a ball-milled coconut shell biochar-micron zero-valent iron-calcium polysulfide composite material in Example 1, Fe represents ball-milled micron zero-valent iron, Fe+S represents ball-milled micron zero-valent iron + calcium polysulfide, BC+S represents ball-milled coconut shell biochar + calcium polysulfide, Fe+BC+S represents ball-milled coconut shell biochar + micron zero-valent iron + calcium polysulfide, ◆ represents S, ● represents Fe; Figure 3 The figure shows the Fourier transform infrared spectrum of a ball-milled coconut shell biochar-micron zero-valent iron-calcium polysulfide composite material in Example 1, where Fe represents ball-milled micron zero-valent iron, Fe+S represents ball-milled micron zero-valent iron + calcium polysulfide, BC+S represents ball-milled coconut shell biochar + calcium polysulfide, and Fe+BC+S represents ball-milled coconut shell biochar-micron zero-valent iron-calcium polysulfide. Figure 4 The kinetic experimental diagram of a coconut shell biochar-micron zero-valent iron-calcium polysulfide composite ball-milled material in Example 1 is shown. 1 represents the kinetic first-order model fitting Pb(II), 2 represents the kinetic second-order model fitting Pb(II), and 3 represents the kinetic Avrami model fitting Pb(II); Figure 5It represents the isotherm experimental diagram of a coconut shell biochar-micron zero-valent iron-calcium polysulfide composite ball-milled material in Example 1, ● represents 20℃, ■ represents 35℃, ▲ represents 50℃, 1 represents the Langmuir model fitting at 20℃, 2 represents the Freundlich model fitting at 20℃, 3 represents the Sips model fitting at 20℃, 4 represents the Langmuir model fitting at 35℃, 5 represents the Freundlich model fitting at 35℃, 6 represents the Sips model fitting at 35℃, 7 represents the Langmuir model fitting at 50℃, 8 represents the Freundlich model fitting at 50℃, and 9 represents the Sips model fitting at 50℃. DETAILED DESCRIPTION

[0013] Specific embodiment 1: This embodiment is a method for preparing a shell biochar-micron zero-valent iron-calcium polysulfide composite ball-milled material, which is carried out according to the following steps: Step S1, pre-treatment of shell biochar: The shell biomass is crushed and sieved using a crusher, and then pyrolyzed using a tubular furnace to obtain pre-treated shell biochar; Step S2: preparing shell biochar-micronized zero-valent iron-calcium polysulfide composite ball-milled material: The pretreated shell biochar, micron zero-valent iron and calcium polysulfide obtained in step S1 are mixed evenly and then transferred to a stainless steel tank of a ball mill. Three zirconium oxide balls with different particle sizes are added to the stainless steel tank of the ball mill, mixed evenly and then ball milled. After the ball milling is completed, the material in the stainless steel tank of the ball mill is taken out and sieved to obtain a shell biochar-micron zero-valent iron-calcium polysulfide composite ball-milled material. The mass ratio of the pretreated shell biochar, micron zero-valent iron and calcium polysulfide is 1: (3.35~16.5):10.

[0014] Specific embodiment 2: This embodiment differs from specific embodiment 1 in that the shell biomass described in step S1 is coconut shell.

[0015] The other steps are the same as those in the first embodiment.

[0016] Specific embodiment three: This embodiment differs from specific embodiment one or two in that: in step S1 , the powder is sieved through a 200-mesh sieve after being crushed.

[0017] The other steps are the same as those in the first or second embodiment.

[0018] Specific embodiment 4: This embodiment differs from specific embodiments 1 to 3 in that: in step S1 , the pyrolysis temperature is 300-700° C., and the pyrolysis time is 2-6 hours.

[0019] The other steps are the same as those in Specific Embodiments 1 to 3.

[0020] Specific embodiment 5: The difference between this embodiment and specific embodiments 1 to 4 is that the mass ratio of the total mass of the pre-treated shell biochar, micron zero-valent iron and calcium polysulfide to the zirconia balls in step S2 is 1: (30~40).

[0021] The other steps are the same as those in Specific Embodiments 1 to 4.

[0022] Specific embodiment 6: The difference between this embodiment and specific embodiments 1 to 5 is that in step S2, the quantity ratio of the three zirconia balls with different particle sizes in descending order is 2:16:15.

[0023] The other steps are the same as those in Specific Embodiments 1 to 5.

[0024] Specific embodiment seven: This embodiment differs from specific embodiments one to six in that: in step S2, ball milling is performed at a rotation speed of 300-700 r / min for 2-12 hours.

[0025] The other steps are the same as those in Specific Embodiments 1 to 6.

[0026] Specific embodiment eight: This embodiment differs from specific embodiments one to seven in that: in step S2, the stirring direction is changed every 1 to 3 hours during the ball milling process.

[0027] The other steps are the same as those in Specific Embodiments 1 to 7.

[0028] Specific embodiment 9: The difference between this embodiment and specific embodiments 1 to 8 is that: after the grinding in step S2 is completed, the mixture is sieved through a 200-mesh screen.

[0029] The other steps are the same as those in Specific Embodiments 1 to 8.

[0030] Specific embodiment ten: This embodiment provides an application of a shell biochar-micron zero-valent iron-calcium polysulfide composite ball-milled material, and the application of the shell biochar-micron zero-valent iron-calcium polysulfide composite ball-milled material in passivating heavy metals lead, cadmium and zinc and improving acidic soil.

[0031] The following examples are used to verify the beneficial effects of the present invention: Example 1: A method for preparing a shell biochar-micron zero-valent iron-calcium polysulfide composite ball-milled material, comprising the following steps: Step S1, pre-treatment of coconut shell biochar: The coconut shell was crushed by a crusher and passed through a 200-mesh sieve. Then, it was pyrolyzed at 500°C for 2 h in a tubular furnace to obtain pre-treated coconut shell biochar for later use. Step S2: preparing shell biochar-micronized zero-valent iron-calcium polysulfide composite ball-milled material: 0.1 g of pre-treated coconut shell biochar, 1 g of micron zero-valent iron and 1.2525 g of calcium polysulfide were added to a beaker and stirred evenly with a glass rod to obtain a mixture; the mixture was transferred to a stainless steel tank of a ball mill, and three types of zirconium oxide balls were added to the stainless steel tank of the ball mill according to the ratio of large balls: medium balls: small balls = 2:16:15. After mixing evenly, the mixture was ball-milled at a speed of 500 r / min for 2 hours, and the stirring direction was changed every 1 hour during the ball milling process; after the ball milling, the material in the stainless steel tank of the ball mill was taken out, and after the grinding was completed, it was sieved through a 200-mesh sieve to obtain a coconut shell biochar-micron zero-valent iron-calcium polysulfide composite ball-milled material, wherein the molar ratio of carbon, sulfur and iron in the coconut shell biochar-micron zero-valent iron-calcium polysulfide composite ball-milled material was 1:2.5:10.

[0032] The mass ratio of the total mass of the coconut shell biochar, micron zero-valent iron and calcium polysulfide after pretreatment in step S2 to the mass ratio of the zirconium oxide balls is 1:30.

[0033] The coconut shell biochar-micronized zero-valent iron-calcium polysulfide composite ball-milled material prepared in this example was subjected to scanning electron microscopy, X-ray diffraction characterization, Fourier transform infrared spectroscopy, kinetic experiments, and isotherm experiments. The specific conclusions are as follows: 1. Characterization (Scanning Electron Microscopy, Fourier Transform Infrared Spectroscopy and X-ray Diffraction): The surface morphology, functional groups and elemental composition of coconut shell biochar-micron zero-valent iron-calcium polysulfide composite ball-milled materials were determined by scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction.

[0034] Figure 1 The scanning electron microscope image of a coconut shell biochar-micron zero-valent iron-calcium polysulfide composite ball-milled material in Example 1 is shown; Figure 1 As shown, the surface of the coconut shell biochar-micron zero-valent iron-calcium polysulfide composite ball-milled material has a large number of irregular flaky multilayer structures arranged together, and the center of the material has an irregular particle distribution, indicating the successful synthesis of the coconut shell biochar-micron zero-valent iron-calcium polysulfide composite ball-milled material and its excellent ability to capture pollutants.

[0035] Figure 2 represents an X-ray diffraction pattern of a coconut shell biochar-micron zero-valent iron-calcium polysulfide composite ball-milled material in Example 1, Fe represents ball-milled micron zero-valent iron, Fe+S represents ball-milled micron zero-valent iron + calcium polysulfide, BC+S represents ball-milled coconut shell biochar + calcium polysulfide, Fe+BC+S represents ball-milled coconut shell biochar + micron zero-valent iron + calcium polysulfide, ◆ represents S, ● represents Fe; Figure 2As shown in the figure, the main phases in the coconut shell biochar-micron zero-valent iron-calcium polysulfide composite ball-milled material are zero-valent iron and sulfur derivatives, etc., which proves the successful synthesis of the material.

[0036] Figure 3 The Fourier transform infrared spectrum of a coconut shell biochar-micron zero-valent iron-calcium polysulfide composite ball-milled material in Example 1 is shown, where Fe represents ball-milled micron zero-valent iron, Fe+S represents ball-milled micron zero-valent iron + calcium polysulfide, BC+S represents ball-milled coconut shell biochar + calcium polysulfide, and Fe+BC+S represents ball-milled coconut shell biochar-micron zero-valent iron-calcium polysulfide; Figure 3 As shown in the figure, the coconut shell biochar-micron zero-valent iron-calcium polysulfide composite ball-milled material has characteristic peaks of hydroxyl, carbonyl and iron, indicating that the ball milling treatment successfully combines coconut shell biochar, micron zero-valent iron and calcium polysulfide and enhances their effects.

[0037] 2. Dynamics: The adsorption process is as follows: the initial concentration of the Pb solution is 250 mg / L, the pH is 5, and the temperature is 25°C. The dosage of the coconut shell biochar-micron zero-valent iron-calcium polysulfide composite ball-milled material prepared in this example is 0.5 g / L. The material is added to 100 mL of the pollutant solution and placed in a water bath shaker at 25°C for adsorption for 20 minutes.

[0038] Figure 4 The kinetic experimental diagram of a coconut shell biochar-micron zero-valent iron-calcium polysulfide composite ball-milled material in Example 1 is shown, 1 represents the kinetic first-order model fitting Pb(II), 2 represents the kinetic second-order model fitting Pb(II), and 3 represents the kinetic Avrami model fitting Pb(II); Figure 4 As shown, the adsorption of Pb(II) increases dramatically within the first 5 minutes. This is due to the large number of adsorption sites provided by the coconut shell biochar-micronized zero-valent iron-calcium polysulfide composite ball-milled material. After a period of reaction, the adsorption sites are gradually occupied by the pollutants, reaching adsorption equilibrium around 15 minutes. Furthermore, the Avrami kinetic model best describes Pb(II) adsorption, demonstrating the existence of multiple dynamics between Pb(II) and the coconut shell biochar-micronized zero-valent iron-calcium polysulfide composite ball-milled material during the adsorption process.

[0039] 3. Isotherm: Isotherm conditions; the concentration range of the Pb solution is 250 mg / L~700 mg / L, and the dosage of the coconut shell biochar-micron zero-valent iron-calcium polysulfide composite ball-milled material prepared in this embodiment is 0.5 g / L; 0.05 g of the material was added to 100 mL of pollutant solutions of different concentrations, and adsorbed in a water bath shaker at 20°C, 35°C and 50°C and a pH of 5 for 20 minutes.

[0040] Figure 5 It represents the isotherm experimental diagram of a coconut shell biochar-micron zero-valent iron-calcium polysulfide composite ball-milled material in Example 1, ● represents 20℃, ■ represents 35℃, ▲ represents 50℃, 1 represents the Langmuir model fitting at 20℃, 2 represents the Freundlich model fitting at 20℃, 3 represents the Sips model fitting at 20℃, 4 represents the Langmuir model fitting at 35℃, 5 represents the Freundlich model fitting at 35℃, 6 represents the Sips model fitting at 35℃, 7 represents the Langmuir model fitting at 50℃, 8 represents the Freundlich model fitting at 50℃, and 9 represents the Sips model fitting at 50℃.

[0041] like Figure 5 As shown, driven by a concentration gradient, the adsorption of Pb(II) by the coconut shell biochar-micronized zero-valent iron-calcium polysulfide composite ball-milled material gradually increased with increasing Pb(II) concentration at various temperatures. However, as the Pb(II) concentration further increased, intense competition among the limited activation sites resulted in a slower increase in Pb(II) adsorption until equilibrium was reached. Furthermore, the Pb(II) adsorption efficiency gradually increased between 20 and 50°C, indicating that the Pb(II) adsorption process is exothermic.

[0042] The high correlation coefficient between the Sips and Freundlich models well simulated the adsorption isotherm data, indicating that the adsorption sites of the coconut shell biochar-micronized zero-valent iron-calcium polysulfide composite ball-milled material for Pb(II) are multi-molecular layer. Furthermore, the maximum Pb(II) adsorption capacity of the coconut shell biochar-micronized zero-valent iron-calcium polysulfide composite ball-milled material at room temperature (20°C) was approximately 479.85 mg / g, fully demonstrating the excellent Pb(II) adsorption performance of the coconut shell biochar-micronized zero-valent iron-calcium polysulfide composite ball-milled material.

[0043] In summary, the coconut shell biochar-micron zero-valent iron-calcium polysulfide composite ball-milled material prepared in this embodiment is an adsorption material that has an effective effect on removing Pb(II) in water, and the removal of Pb(II) is rapid.

Claims

1. A method for preparing shell biochar-micron zero-valent iron-calcium polysulfide composite ball-milled material, characterized in that The preparation method is carried out according to the following steps: Step S1, pre-treatment of shell biochar: The shell biomass is crushed and sieved using a crusher, and then pyrolyzed using a tubular furnace to obtain pre-treated shell biochar; Step S2: preparing shell biochar-micronized zero-valent iron-calcium polysulfide composite ball-milled material: The pretreated shell biochar, micron zero-valent iron and calcium polysulfide obtained in step S1 are mixed evenly and then transferred to a stainless steel tank of a ball mill. Three zirconium oxide balls with different particle sizes are added to the stainless steel tank of the ball mill, mixed evenly and then ball milled. After the ball milling is completed, the material in the stainless steel tank of the ball mill is taken out and sieved to obtain a shell biochar-micron zero-valent iron-calcium polysulfide composite ball-milled material. The mass ratio of the pretreated shell biochar, micron zero-valent iron and calcium polysulfide is 1: (3.35~16.5):

10.

2. The method for preparing a shell biochar-micron zero-valent iron-calcium polysulfide composite ball-milled material according to claim 1, characterized in that The shell biomass described in step S1 is coconut shell.

3. The method for preparing a shell biochar-micron zero-valent iron-calcium polysulfide composite ball-milled material according to claim 1, characterized in that After being crushed in step S1, the product is passed through a 200-mesh sieve.

4. The method for preparing a shell biochar-micron zero-valent iron-calcium polysulfide composite ball-milled material according to claim 1, characterized in that In step S1, the pyrolysis temperature is 300-700° C., and the pyrolysis time is 2-6 hours.

5. The method for preparing a shell biochar-micron zero-valent iron-calcium polysulfide composite ball-milled material according to claim 1, characterized in that The mass ratio of the total mass of the shell biochar, micron zero-valent iron and calcium polysulfide after pretreatment in step S2 to the mass ratio of the zirconia balls is 1: (30-40).

6. The method for preparing a shell biochar-micron zero-valent iron-calcium polysulfide composite ball-milled material according to claim 1, characterized in that In step S2, the ratio of the number of the three zirconia balls with different particle sizes in descending order is 2:16:

15.

7. The method for preparing a shell biochar-micron zero-valent iron-calcium polysulfide composite ball-milled material according to claim 1, characterized in that In step S2, the ball milling is performed at a rotation speed of 300-700 r / min for 2-12 hours.

8. The method for preparing a shell biochar-micron zero-valent iron-calcium polysulfide composite ball-milled material according to claim 1, characterized in that In step S2, the stirring direction is changed every 1 to 3 hours during the ball milling process.

9. The method for preparing a shell biochar-micron zero-valent iron-calcium polysulfide composite ball-milled material according to claim 1, characterized in that After grinding in step S2, the mixture is passed through a 200-mesh sieve.

10. Application of a shell biochar-micron zero-valent iron-calcium polysulfide composite ball-milled material prepared by the method according to any one of claims 1 to 9, characterized in that The shell biochar-micron zero-valent iron-calcium polysulfide composite ball-milled material is used in passivating heavy metals lead, cadmium and zinc and improving acidic soil.

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