Micro-plastic modified magnetite powder as well as preparation method and application thereof

Abstract

The invention discloses a preparation method and application of microplastic modified magnetite, and belongs to the technical field of heavy metal wastewater treatment. The micro-plastic modified magnetite is prepared by mixing and ball-milling micro-plastic and magnetite powder and carrying out surface modification on the magnetite powder by using the micro-plastic, wherein the mass ratio of the micro plastic to the magnetite powder is (2-4): 100. When the microplastic modified magnetite powder is used for treating wastewater containing heavy metal, Cd (II), Cu (II) and Pb (II) can be safely, efficiently and quickly removed under the wide pH condition, and the heavy metal is quickly separated and recovered through magnetism; according to the method, resource utilization of pollutant microplastics and separation and recovery of heavy metal are achieved at the same time, the process is simple, conditions are mild, and the method has important application prospects.

Description

Technical Field

[0001] The invention belongs to the technical field of heavy metal wastewater treatment, and particularly relates to microplastic modified magnetite powder, a preparation method and application thereof. Background Art

[0002] With the acceleration of China's industrialization, heavy metal emissions are increasing, becoming a significant pollutant in water, soil, and the atmosphere. Heavy metals in the environment originate primarily from two sources: natural sources, including processes such as volcanic activity, crustal weathering, and soil erosion. These inputs are generally highly regional and cyclical, contributing relatively little to the overall environmental burden. Anthropogenic sources include industrial emissions, pesticide pollution, transportation, and urban solid waste. Heavy metals are non-biodegradable and accumulate in organisms, posing a threat to ecosystems and human health. For example, lead and cadmium can inhibit plant photosynthesis, reduce root absorption capacity, and contribute to vegetation degradation. The accumulation of heavy metals like lead, cadmium, and mercury in the human body can cause neurological diseases (such as Minamata disease) and Itai-itai disease, posing a significant threat to the ecological environment and life.

[0003] Currently, the commonly used heavy metal wastewater treatment technologies include chemical precipitation, ion exchange, and reverse osmosis membrane separation. Although the above methods can effectively remove heavy metals, they generally face problems such as high treatment costs and the tendency to cause secondary pollution. Adsorption is a common method for removing heavy metal ions from water bodies. It has the advantages of simple operation, high removal efficiency, and reusable materials. Magnetite (Fe3O4) is a magnetic mineral with high natural reserves. It can achieve rapid solid-liquid separation under the action of an external magnetic field. However, magnetite has defects such as few surface functional groups and small specific surface area, and its adsorption performance is limited. Therefore, it is necessary to develop effective modification methods to improve its adsorption performance. Summary of the Invention

[0004] The purpose of the present invention is to provide a microplastic-modified magnetite powder, a preparation method and application thereof. The obtained microplastic-modified magnetite powder can efficiently and quickly remove heavy metal ions under a wide pH condition, while realizing the resource utilization of pollutant microplastics and the separation and recovery of heavy metals, and has important application prospects.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions: Provided is a microplastic-modified magnetite powder, which is prepared by mixing microplastics and magnetite powder, ball-milling the mixture, and surface-modifying the magnetite powder using the microplastics; wherein the mass ratio of the microplastics to the magnetite powder is 2-4:100.

[0006] According to the above scheme, the ball milling time is 1 to 6 hours, preferably 4 to 6 hours.

[0007] According to the above scheme, the particle size of the microplastics is 10~300μm.

[0008] According to the above solution, the microplastic is at least one of polyethylene terephthalate (PET), polypropylene (PP) or polystyrene (PS).

[0009] A method for preparing the microplastic-modified magnetite powder is provided, comprising the following steps: The microplastics and magnetite powder are mixed and ball-milled to obtain the microplastic-modified magnetite powder.

[0010] According to the above scheme, when ball milling, select 10 to 20 8 to 10 mm stainless steel balls and 30 to 50 5 to 6 mm stainless steel balls.

[0011] According to the above scheme, the rotation speed of the ball mill is 450~550 r / min.

[0012] According to the above scheme, the ball milling time is 1~6 h.

[0013] Preferably, the ball milling is performed in forward and reverse rotation for 30 to 60 minutes each, followed by 1 to 2 cycles.

[0014] Preferably, the ball milling time is 4 to 6 hours.

[0015] Provided is a specific application of the microplastic modified magnetite powder in treating heavy metal-containing wastewater.

[0016] According to the above scheme, the heavy metal ions in the heavy metal-containing wastewater are at least one of Cd(II), Cu(II) and Pb(II).

[0017] According to the above scheme, the specific application is: adding microplastic modified magnetite powder to heavy metal-containing wastewater to react and remove heavy metals.

[0018] Preferably, the reaction temperature is 20-45° C., and the reaction time is 30-120 min, preferably 50-70 min.

[0019] Preferably, the reaction is carried out in an oscillator at a rotation speed of 200-220 rpm.

[0020] According to the above scheme, the pH value of the heavy metal-containing wastewater is 4-9; preferably 5.5-9, more preferably 6-7.

[0021] According to the above scheme, the initial concentration of the heavy metal-containing wastewater is 5-10 mg / L.

[0022] According to the above scheme, the mass volume ratio of microplastic modified magnetite powder to heavy metal wastewater is 1-3g / L.

[0023] The beneficial effects of the present invention are as follows: 1. The present invention provides a microplastic-modified magnetite powder. The magnetite powder is modified using microplastic powder, an emerging environmental pollutant. The dense oxide layer on the surface of the magnetite powder is destroyed by ball milling to activate the magnetite powder. At the same time, the aging of the microplastic powder is accelerated, the stable microplastic structure is torn, and more structural functional groups are exposed, which is conducive to reaction and combination with the activated magnetite powder, thereby increasing the types and number of functional groups on the surface of the magnetite powder, reconstructing the structure of the magnetite, and increasing adsorption sites, which is conducive to the adsorption and removal of heavy metal ions in water. The combination with the hydrophilic magnetite powder also significantly reduces the hydrophobicity of the microplastics, accelerating their adsorption of heavy metals in wastewater. The microplastic-modified magnetite powder obtained by the present invention, when used to treat heavy metal-containing wastewater, can safely, efficiently and quickly remove heavy metal ions such as Cd(II), Cu(II) and Pb(II) under a wide pH condition, and recover the heavy metals through rapid magnetic separation. The present invention simultaneously realizes the resource utilization of pollutant microplastics and the separation and recovery of heavy metals, and has important application prospects.

[0024] 2. The present invention provides a method for preparing microplastic-modified magnetite powder, which achieves the modification of microplastics on the surface of magnetite powder through simple ball milling. The process is simple, the conditions are mild, and it is conducive to industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments and comparative examples are briefly introduced below.

[0026] Figure 1 The X-ray crystal diffraction patterns of the PET modified magnetite powder obtained in Example 1 of the present invention and the ball-milled magnetite powder obtained in Comparative Example 1 are shown.

[0027] Figure 2 This is a diagram showing the effects of microplastic-modified magnetite powders PET1-Fe3O4, PET2-Fe3O4, PET3-Fe3O4 and PET4-Fe3O4 obtained from the same raw materials in different mass ratios in Examples 9 and 10 of the present invention, and Fe3O4 obtained from Comparative Example 1 in treating Cd(II) in polluted water.

[0028] Figure 3 This is a diagram showing the adsorption effect of PET-modified magnetite powder on Cd(II) in the presence of common interfering ions in Example 12 of the present invention.

[0029] Figure 4 This is a diagram showing the effect of using PET-modified magnetite powder from different manufacturers in Example 13 of the present invention to treat Cd(II) in polluted water.

[0030] Figure 5 This is a diagram showing the effect of using PET-modified magnetite powder in Example 14 of the present invention to treat Cd(II) in contaminated water bodies with different initial pH values.

[0031] Figure 6 This is a diagram showing the effect of using PET-modified magnetite powder in Example 16 of the present invention to treat a mixed solution of Cu(II) and Pb(II) in polluted water.

[0032] Figure 7 FTIR (Fourier transform infrared spectra) of the PET modified magnetite powder obtained from the magnetite powder in Example 1 of the present invention and the ball-milled magnetite powder obtained in Comparative Example 1 before and after adsorption. DETAILED DESCRIPTION

[0033] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0034] Example 1 Provided is a method for preparing microplastic (PET) modified magnetite powder, comprising the following steps: A ball mill was added with 2 g of magnetite powder and 0.04 g of polyethylene terephthalate (PET, average particle size 20 μm) (magnetite powder / PET mass ratio of 100:2). Twenty 10 mm diameter stainless steel beads and 50 6 mm stainless steel beads were selected. The ball mill was set at 500 rpm for one hour each of forward and reverse rotation, followed by one cycle, for a total of four hours to obtain microplastic-modified magnetite powder, designated PET2-Fe3O4 (or PET-Fe3O4-4).

[0035] Example 2 The specific operation is the same as that of Example 1, except that the mass ratio of magnetite powder to PET is 100:3, and the obtained microplastic modified magnetite powder is recorded as PET3-Fe3O4.

[0036] Example 3 The specific operation is the same as that of Example 1, except that the mass ratio of magnetite powder to PET is 100:4, and the obtained microplastic modified magnetite powder is recorded as PET4-Fe3O4.

[0037] Example 4 The specific operation was the same as in Example 1, except that the ball milling time was 1 h. The obtained microplastic modified magnetite powder was recorded as PET-Fe3O4-1.

[0038] Example 5 The specific operation was the same as in Example 1, except that the ball milling time was 2 h. The obtained microplastic modified magnetite powder was recorded as PET-Fe3O4-2.

[0039] Example 6 The specific operation was the same as in Example 1, except that the ball milling time was 6 h. The obtained microplastic modified magnetite powder was recorded as PET-Fe3O4-6.

[0040] Example 7 The specific operation is the same as that in Example 1, except that the PET used comes from different manufacturers than that in Example 1, namely, manufacturer A (average particle size 20 μm), manufacturer B (average particle size 20 μm) and manufacturer C (average particle size 200 μm). The obtained microplastic modified magnetite powders are respectively recorded as PET-Fe3O4-A, PET-Fe3O4-B and PET-Fe3O4-C.

[0041] Comparative Example 1 The specific operation is the same as that of Example 1, except that the magnetite powder is directly ball-milled without adding PET. The magnetite powder obtained by ball milling is recorded as Fe3O4.

[0042] The crystal structures of PET2-Fe3O4 obtained in Example 1 and Fe3O4 obtained in Comparative Example 1 were characterized by X-ray powder diffractometer. Figure 1 . Figure 1 It shows that the main components of Fe3O4 obtained in Comparative Example 1 are Fe3O4 and Fe2O3, while the crystallization performance of the modified magnet powder with the addition of PET is significantly enhanced, the stability of the material is enhanced, and it contains a small amount of zero-valent iron.

[0043] Figure 7 The FTIR of the PET modified magnetite powder obtained in Example 1 of the present invention and the magnetite powder obtained in Comparative Example 1 before and after adsorption of Cd (II) is shown in the figure: the obtained microplastic modified magnetite powder (PET2-Fe3O4) has a Cd(II) content of 1617 cm -1 There is a peak at 569.8, which is the C=O bond of the benzene ring on PET, indicating that the microplastic has been successfully modified to the surface of the mineral Fe3O4; the peak at 569.8 is the Fe-O bond. The size of the peak can be seen to have changed significantly before and after adsorption, indicating that Cd (II) has combined with the Fe-O bond; 933.5cm -1 It is a -OH bond. It can be inferred that when PET2-Fe3O4 is adsorbed, not only the Fe-O bond in the magnetite powder adsorbs Cd (Ⅱ), but the functional groups -OH and -COOH modified by PET will also combine with Cd (Ⅱ).

[0044] Comparative Example 2 The specific operation is the same as that of Example 1, except that the mass ratio of magnetite powder to PET is 100:1, and the obtained microplastic modified magnetite powder is recorded as PET1-Fe3O4.

[0045] Example 9 Provided is a method for applying the PET-modified magnetite powder to remove Cd(II), comprising the following steps: Weigh 0.15 g of the PET-modified magnetite powder (PET2-Fe3O4) obtained in Example 1 and add it to 50 mL of a 5 mg / L Cd(II) solution with an initial pH of 5.5. The conical flask was placed in an oscillator (200 rpm, 25°C) to conduct the experiment. Cd(II) removal was measured after 60 minutes of reaction. Finally, a magnet was used to separate the modified magnetite powder and wastewater solution, completing the Cd(II) wastewater treatment.

[0046] Example 10 A method for applying the above-mentioned PET modified magnetite powder to remove Cd(II) is provided. The Fe3O4 powder obtained in Comparative Example 1, the modified powder PET1-Fe3O4 obtained in Comparative Example 2, and the PET modified magnetite powders PET3-Fe3O4 and PET4-Fe3O4 obtained in Examples 2-3 are respectively selected to remove Cd(II). The specific operation is the same as that in Example 9.

[0047] The results of removing Cd(II) in Examples 9 and 10 are as follows: Figure 2 As shown, the results show that the removal rates of Cd(II) by Fe3O4, PET1-Fe3O4, PET2-Fe3O4, PET3-Fe3O4, and PET4-Fe3O4 obtained in Comparative Examples 1-2 and Examples 1-3 were 54.2%, 71.1%, 88.2%, 84.8%, and 80.9%, respectively.

[0048] Example 11 A method for applying the PET-modified magnetite powder to remove Cd(II) is provided. The PET-modified magnetite powders are PET-Fe3O4-1, PET-Fe3O4-2, and PET-Fe3O4-6 obtained by ball milling for different times in Examples 4-6. The specific operation is the same as that in Example 9, and the removal rate of Cd(II) is measured.

[0049] The results showed that the Cd(II) removal rates of PET-Fe3O4-1, PET-Fe3O4-2 and PET-Fe3O4-6 modified magnetite powders obtained by different ball milling times in Examples 4-6 were 80.9%, 81.2% and 91% respectively in 60 min.

[0050] Example 12 The adsorption of Cd(II) by PET-modified magnetite powder in the presence of common interfering ions was tested. The specific operation was as follows: The PET2-Fe3O4 obtained in Example 1 was added to 8 groups of 50 mL, 5 mg / L Cd(II) solutions, and Cd(II) was removed according to the same process as in Example 9; wherein the 8 groups of Cd(II) solutions contained interfering ions Na + 、Cu 2 + , Ca 2+ NH4 + , humic acid (FA), hyaluronic acid (HA), Cl - 、SO4 2- The interfering ion concentration is 50 mg / L, and the removal time is 120 min. The results are as follows Figure 3 shown.

[0051] Figure 3 Display, except NH4 + Except for some obvious inhibitory effects on ions, other ions have no inhibitory effects, which proves that PET modified magnetite powder has a better and more stable adsorption effect in different water environments.

[0052] Example 13 A method for removing Cd(II) by using the modified PET magnetite powder is provided. The modified magnetite powder used is PET-Fe3O4-A, PET-Fe3O4-B and PET-Fe3O4-C obtained from magnetite powders of different manufacturers in Example 7. The specific operation is the same as that in Example 9. The results of removing Cd(II) are shown in FIG. Figure 4 shown.

[0053] Figure 4 The results showed that the Cd(II) removal rates of PET-Fe3O4-A, PET-Fe3O4-B, and PET-Fe3O4-C were 78.8%, 82.1%, and 84.5%, respectively, within 60 minutes. These results demonstrate that the modified reduced iron powder obtained by this invention is universally applicable to PET from different manufacturers.

[0054] Example 14 Provided is an application method of the above-mentioned PET modified magnetite powder to remove Cd(II). The specific operation is the same as in Example 9, except that the pH of the Cd(II) solution is adjusted to 4, 5, 6, 7, 8, and 9, respectively. The results are as follows: Figure 5 shown.

[0055] like Figure 5As shown, the PET-modified magnetite powder (PET2-Fe3O4) achieved removal rates of 58.8%, 75.3%, 92.1%, 95.8%, 91.3%, and 90.1% in 60 minutes for Cd(II) solutions with initial pH values ​​of 4, 5, 6, 7, 8, and 9, respectively. This indicates that PET-modified magnetite has a wide pH range for Cd(II) removal, achieving removal rates exceeding 55% under neutral and even acidic conditions. Therefore, the microplastic-modified magnetite obtained by this method can be used to treat Cd(II) wastewater over a wide pH range.

[0056] Example 15 A method for applying the PET-modified magnetite powder to remove Cd(II) is provided. The specific operation is the same as that in Example 9, except that the initial concentration of the Cd(II) solution is 10 mg / L. The Cd(II) removal rate is 70.5% after 60 minutes.

[0057] Example 16 A method for applying the PET-modified magnetite powder to remove Cu(II) and Pb(II) is provided. The specific operation is the same as that in Example 9, except that the Cd(II) solution is replaced with a mixed solution of Cu(II) and Pb(II) with an initial concentration of 10 ppm.

[0058] The results are as follows Figure 6 The results showed that the removal rates of PET2-Fe3O4 for a mixed solution of Cu(II) and Pb(II) with a concentration of 10 mg / L were 50% and 80% respectively in 30 min, and the removal rates of PET2-Fe3O4 for a mixed solution of Cu(II) and Pb(II) with a concentration of 10 mg / L were 70.5% and 99.5% respectively in 60 min.

[0059] Example 17 Provided is a method for preparing microplastic-modified magnetite powder. The specific operation is the same as that in Example 1, except that the microplastic PET is replaced with PS and PP, respectively, to obtain microplastic-modified magnetite powders PP-Fe3O4 and PS-Fe3O4, respectively.

[0060] The modified magnetite powders PP-Fe3O4 and PS-Fe3O4 were respectively selected to remove Cd(II) according to the method of Example 9, and the removal rates of Cd(II) were measured.

[0061] The results showed that the removal rates of PP-Fe3O4 and PS-Fe3O4 for 5 mg / L Cd(II) solution were 95.2% and 92.8% respectively in 60 min.

[0062] The above description is only a partial implementation example of the present invention and does not limit the present invention in any form. Any equivalent changes, modifications and evolutions made to the above implementation examples based on the essential technology of the present invention shall fall within the scope of protection of the technical solution of the present invention.

Claims

1. A microplastic modified magnetite powder, characterized in that: The microplastic-modified magnetite powder is prepared by mixing microplastics and magnetite powder, ball-milling the mixture, and modifying the surface of the magnetite powder using the microplastics. The mass ratio of the microplastics to magnetite powder is 2~4:

100.

2. The microplastic modified magnetite powder according to claim 1, characterized in that The ball milling time is 1 to 6 h.

3. The microplastic modified magnetite powder according to claim 1, characterized in that The microplastic particle size is 10~300μm.

4. The microplastic modified magnetite powder according to claim 1, characterized in that The microplastic is at least one of polyethylene terephthalate, polypropylene or polystyrene.

5. A method for preparing microplastic modified magnetite powder according to any one of claims 1 to 4, characterized in that: The following steps are involved: Microplastics and magnetite powder are mixed and ball-milled to obtain microplastic-modified magnetite powder.

6. The preparation method according to claim 5, characterized in that The ball milling speed is 450-550 r / min.

7. The preparation method according to claim 5, characterized in that The ball milling time is 1 to 6 h.

8. Use of the microplastic-modified magnetite powder according to any one of claims 1 to 4 in treating heavy metal-containing wastewater.

9. The use according to claim 8, characterized in that The heavy metal ions in the heavy metal-containing wastewater are at least one of Cd(II), Cu(II) and Pb(II).

10. The use according to claim 8, characterized in that The pH value of the heavy metal-containing wastewater is 4-9.

Images