Soil micro-plastic electrostatic separation device and method

Abstract

The invention relates to the technical field of soil treatment, and particularly discloses a soil micro-plastic electrostatic separation device and method.The soil micro-plastic electrostatic separation device comprises a sample pool, an electrostatic adsorption mechanism is arranged on one side of the sample pool, and the electrostatic adsorption mechanism is connected with an electrostatic discharge generator through a wire; the electrostatic adsorption mechanism comprises an adsorption plate and a connecting handle; the bottom box and the heightening frame bodies are made of wood, the height of the sample pool can be adjusted by installing the heightening frame bodies in an assembling mode, a nylon coating is arranged on the outer side of an adsorption plate and used for adsorbing micro-plastics and eradicating the risk of high-voltage electric leakage, and the height of the adsorption plate can be adjusted through an arranged supporting assembly; the particle size range of the micro-plastic covered by electrostatic adsorption is wide, compared with a traditional method, the recovery rate is remarkably improved, and the original form of the micro-plastic and the natural structure of soil are protected through normal-temperature physical separation and no reagent addition.

Description

Technical Field

[0001] The present invention belongs to the technical field of soil remediation, and in particular relates to a device and method for electrostatically separating soil microplastics. Background Art

[0002] At present, the research on soil microplastic separation is still in its infancy. Methods include filtration adsorption, coagulation sedimentation, manual screening, density flotation, pressurized fluid extraction, catalytic degradation, microbial degradation, etc. Filtration adsorption and coagulation sedimentation are mainly used to separate microplastic pollutants in water bodies;

[0003] Filtration adsorption and coagulation sedimentation are mainly used to separate microplastic pollutants from water bodies. Artificial screening and density flotation can be used in the pretreatment stage of quantitative analysis of microplastics in a small amount of soil samples, but they have problems such as low efficiency and difficulty in large-scale application. The pressurized fluid extraction method has a high application cost and is very destructive to the soil, making it unsuitable as a method for removing microplastics from farmland soil. Although catalytic degradation has been proven to be effective in removing microplastics from water bodies, it is difficult to degrade microplastics in the soil due to the low oxygen content and weak visible light in the soil. The microbial degradation method has problems such as long application cycle, low efficiency, and susceptibility to complex site conditions and environmental factors. It also poses certain risks to the ecological health of farmland.

[0004] In summary, current separation methods are mainly used for the quantitative detection of microplastics in a small amount of environmental samples and the removal of microplastics in water bodies. They have problems such as difficulty in operation, strong destructiveness to soil, high cost, low efficiency, and small scale, and cannot be widely used to remove microplastics from farmland soil. Summary of the Invention

[0005] The object of the present invention is to provide a soil microplastic electrostatic separation device and method to solve the problems raised in the above background technology.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A soil microplastic electrostatic separation device and method, comprising:

[0008] A sample pool is used to place soil samples. An electrostatic adsorption mechanism is provided on one side of the sample pool for adsorbing microplastics in the soil. The electrostatic adsorption mechanism is connected to an electrostatic discharge generator via a wire, which is used to energize the adsorption plate of the electrostatic adsorption mechanism and generate static electricity, so that the microplastics in the soil will be adsorbed to the lower surface of the electrostatic adsorption plate under the action of electrostatic attraction;

[0009] The electrostatic adsorption mechanism includes an adsorption plate and a connecting handle. The adsorption plate is arranged above the sample pool. The connecting handle is connected to one side of the adsorption plate. One end of the wire passes through the connecting handle and is electrically connected to the adsorption plate. The adsorption plate is configured as a plate that can generate static electricity when energized, which is conducive to electrostatic adsorption of microplastics in the soil.

[0010] Preferably, the adsorption plate is configured as an aluminum plate with a nylon coating on the outside.

[0011] Preferably, the connecting handle is made of insulating material to provide insulation.

[0012] Preferably, the electrostatic adsorption mechanism further includes a support assembly, which is connected to the connecting handle and is used to install the connecting handle and the adsorption plate and adjust their heights.

[0013] Preferably, the support assembly includes a support base, a support rod and a locking piece. The support base is provided on one side of the sample pool, the upper end of the support base is connected to the support rod, and an installation hole that matches the support rod is opened inside one end of the connecting handle. The locking piece is also provided on the support rod for fixing the connecting handle.

[0014] Preferably, the locking member includes two groups of locking nuts, and the support rod is threaded with two groups of locking nuts, and the two groups of locking nuts are respectively located at the upper and lower ends of the mounting holes. When adjusting the height of the adsorption plate and the connecting handle, the two groups of locking nuts are first screwed separately to make the two groups of locking nuts move away from each other, and then the connecting handle is moved on the support rod, and the adsorption plate is driven to move vertically until it reaches an appropriate height. After adjusting the height, the two groups of locking nuts are screwed separately to make the two groups of locking nuts approach each other and clamp the connecting handle to achieve limited fixation.

[0015] Preferably, the sample pool includes a base box and several groups of heightened frames, the base box is configured as a box structure with an open upper end, the heightened frame is configured as a box structure with openings at the upper and lower ends, the upper end of the base box is equipped with the heightened frame, the upper end of the heightened frame and the upper end of the heightened frame are both provided with a card block, the lower end of the heightened frame is provided with a card slot that cooperates with the card block, the two groups of heightened frames are respectively assembled by the card block and the card slot, the number of soil samples placed in the sample pool is adjusted, and then the heightened frame is installed at the upper end of the base box by the card block and the card slot, and the upper end heightened frame is installed at the upper end of the lower end heightened frame by the card block and the card slot, so that the number of heightened frames can be installed according to actual usage, and the height of the sample pool can be adjusted.

[0016] Preferably, a separation method according to the above-mentioned soil microplastic electrostatic separation device comprises the following steps:

[0017] S1. Soil sample pretreatment: First, the collected soil samples containing microplastics are dried, then fully crushed to destroy large aggregates, and then sieved to remove large impurities for standby use;

[0018] S2. Electrostatic separation of microplastics: Place the pretreated soil sample into the sample pool. The soil sample is laid flush with the upper edge of the sample pool. Adjust the height of the adsorption plate so that the adsorption plate is placed parallel to the sample pool at 0.5 cm above the sample pool. Connect its wire to the negative electrode of the electrostatic discharge generator. Power the adsorption plate so that the adsorption plate electrostatically adsorbs the microplastics in the soil sample placed in the sample pool under the action of static electricity, thereby separating the microplastics from the soil sample.

[0019] S3. Collection of microplastic samples. After the electrostatic discharge generator is turned on, the microplastics in the soil sample are adsorbed onto the electrostatic adsorption plate under the action of electrostatic attraction. The microplastic samples on the electrostatic adsorption plate are then swept and recovered using an electrostatic dust removal brush. The separation and recovery steps are repeated multiple times depending on the content and type of microplastics in the sample.

[0020] Preferably, the soil sample containing microplastics in S1 is dried at 25°C;

[0021] The soil sample after crushing in S1 was passed through a 5 mm coarse sieve.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The base box and heightened frame are both made of wood, and the number of heightened frames is assembled. The height of the sample pool can be adjusted, eliminating the need to customize containers of multiple specifications, saving raw materials and storage space. The outer side of the adsorption plate is coated with nylon to eliminate the risk of high-voltage leakage. It carries a charge opposite to that of microplastics and is used to adsorb microplastics. The support assembly can adjust the height of the adsorption plate, making it easy to adjust according to actual usage. The connecting handle can be held and installed through the support assembly, making it suitable for both laboratory and field scenarios.

[0024] 2. Electrostatic adsorption covers a wide range of microplastic particle sizes. Compared with traditional methods, the recovery rate is significantly improved. Through physical separation at room temperature, no reagents are added, and the original form of microplastics and the natural structure of the soil are protected. Electrostatic adsorption responds instantly, and a single separation takes only a few minutes. It is time-saving and efficient. The operation only requires electricity and no consumable materials. Compared with traditional methods, the long-term use cost is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0026] Figure 2 This is a schematic diagram of the working state simulation of the present invention;

[0027] Figure 3 The working state of the present invention is shown as follows Figure 1 ;

[0028] Figure 4 The working state of the present invention is shown as follows Figure 2 ;

[0029] In the figure: 10, sample pool; 11, bottom box; 12, heightened frame;

[0030] 20. Electrostatic adsorption mechanism; 21. Adsorption plate; 22. Connecting handle; 23. Support base; 24. Support rod; 25. Locking member;

[0031] 30. Electrostatic discharge generator; 31. Wire. DETAILED DESCRIPTION

[0032] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0033] Example 1:

[0034] See also Figure 1 As shown, a soil microplastic electrostatic separation device comprises:

[0035] The sample pool 10 is used to place soil samples. An electrostatic adsorption mechanism 20 is provided on one side of the sample pool 10 for adsorbing microplastics in the soil. The electrostatic adsorption mechanism 20 is connected to an electrostatic discharge generator 30 via a wire 31, which is used to energize the adsorption plate 21 of the electrostatic adsorption mechanism 20 and generate static electricity, so that the microplastics in the soil will be adsorbed to the lower surface of the electrostatic adsorption plate 21 under the action of electrostatic attraction;

[0036] The electrostatic adsorption mechanism 20 includes an adsorption plate 21 and a connecting handle 22. The adsorption plate 21 is arranged above the sample pool 10. The connecting handle 22 is connected to one side of the adsorption plate 21. One end of the wire 31 passes through the connecting handle 22 and is electrically connected to the adsorption plate 21. The inner core of the adsorption plate 21 is set to be a conductive plate, which is covered with a polymer coating for conducting electricity and releasing charges, which is conducive to electrostatic adsorption of microplastics in the soil.

[0037] refer to Figure 1As shown, the adsorption plate 21 is configured as an aluminum plate with a nylon coating on the outside, that is, the inner core of the adsorption plate 21 is configured as an aluminum plate, and the outside of the inner core is wrapped with a nylon coating, which can fully cover the inner core so that it is not exposed, thereby eliminating the risk of high-voltage leakage. Furthermore, the thickness of the coating can be 0.2 cm. While wrapping, it carries an electric charge opposite to that of the microplastics for adsorbing the microplastics, so that the adsorption plate 21 produces an electrostatic adsorption effect on the microplastics.

[0038] It should be noted that the function of aluminum plate itself is to conduct electricity and release electric charges. It cannot absorb microplastics by itself, so it needs to be covered with nylon coating. In fact, it is through the contact between the aluminum plate and the nylon coating that the nylon coating carries the opposite charge to the microplastics, thereby achieving the effect of absorbing microplastics.

[0039] refer to Figure 1 As shown, the connecting handle 22 is made of insulating material and plays an insulating role.

[0040] refer to Figure 1 As shown, the electrostatic adsorption mechanism 20 further includes a support assembly, which is connected to the connecting handle 22 and is used to install the connecting handle 22 and the adsorption plate 21 and adjust their heights.

[0041] refer to Figure 1 As shown, the support assembly includes a support base 23, a support rod 24 and a locking piece 25. A support base 23 is provided on one side of the sample pool 10, and the upper end of the support base 23 is connected to the support rod 24. A mounting hole that matches the support rod 24 is opened inside one end of the connecting handle 22. A locking piece 25 is also provided on the support rod 24 for fixing the connecting handle 22, which is suitable for laboratory scenes.

[0042] refer to Figure 1 As shown, the locking member 25 includes two sets of locking nuts, and the support rod 24 is threaded with two sets of locking nuts. The two sets of locking nuts are respectively located at the upper and lower ends of the mounting holes. When adjusting the height of the adsorption plate 21 and the connecting handle 22, the two sets of locking nuts are first screwed separately to make the two sets of locking nuts move away from each other, and then the connecting handle 22 is moved on the support rod 24, and the adsorption plate 21 is driven to move vertically until it reaches an appropriate height. After adjusting the height, the two sets of locking nuts are screwed separately to make the two sets of locking nuts close to each other and clamp the connecting handle 22 to achieve limited fixation.

[0043] It should be noted that the present invention can also omit the support assembly, so that the staff can operate it by holding the connecting handle 22, which is suitable for outdoor scenes.

[0044] refer to Figure 1As shown, the sample pool 10 includes a base box 11 and several groups of heightened frames 12. The base box 11 is configured as a box structure with an upper end opening, and the heightened frame 12 is configured as a box structure with openings at both the upper and lower ends. The upper end of the base box 11 is installed with a heightened frame 12, and the upper end of the heightened frame 12 and the upper end of the heightened frame 12 are both provided with a card block, and the lower end of the heightened frame 12 is provided with a card slot that cooperates with the card block. The two groups of heightened frames 12 are assembled by the card block and the card slot respectively, which can adjust the number of soil samples placed in the sample pool 10, and then during installation, the heightened frame 12 is installed on the upper end of the base box 11 by the card block and the card slot, and the upper end heightened frame 12 is installed on the upper end of the lower end heightened frame 12 by the card block and the card slot, so that the number of heightened frames 12 can be installed according to actual usage conditions, and then the height of the sample pool 10 can be adjusted.

[0045] The bottom box 11 and the heightened frame 12 are both made of wood, and the number of heightened frames 12 is assembled to adjust the height of the sample pool 10. There is no need to customize containers of multiple specifications, saving raw materials and storage space.

[0046] Example 2:

[0047] refer to Figure 1 As shown, a separation method according to the above-mentioned soil microplastic electrostatic separation device comprises the following steps:

[0048] S1. Pretreatment of soil samples: First, dry the collected soil samples containing microplastics, then fully crush them to destroy large aggregates, and then sieve them to remove large impurities such as gravel and plant residues before use;

[0049] S2, electrostatic separation of microplastics, the soil sample after pretreatment is spread into the sample pool 10, the laying height of the soil sample is flush with the upper edge of the sample pool 10, and the height of the adsorption plate 21 is adjusted. According to needs, it can be handheld or fixed. Use the soil microplastic electrostatic separation device, place the adsorption plate 21 parallel to 0.5 cm above the sample pool 10, connect its wire 31 to the negative pole of the electrostatic discharge generator 30, turn on the electrostatic discharge generator 30, adjust the voltage according to actual needs, and the recommended range is 20KV-30KV. Power on the adsorption plate 21 so that the adsorption plate 21 electrostatically adsorbs the microplastics in the soil sample spread into the sample pool 10 under the action of static electricity, so that the microplastics are separated from the soil sample (such as Figure 2 shown);

[0050] The electrostatic discharge generator 30 is an optional market product, requiring an adjustable voltage of 3KV-120KV, positive and negative polarity switching output, an ambient temperature of -15-50℃, an output current of 0-2mA, and automatic cut-off of high voltage output due to overcurrent.

[0051] S3, microplastic sample collection, after the electrostatic discharge generator 30 is turned on (such as Figure 3 As shown in FIG), the microplastics in the soil sample are adsorbed onto the electrostatic adsorption plate 21 (as shown in FIG) under the action of electrostatic attraction. Figure 4 As shown), the microplastic samples on the electrostatic adsorption plate 21 are swept and recovered using an electrostatic dust removal brush, and the separation and recovery steps are repeated multiple times according to the content and type of microplastics in the sample.

[0052] The soil samples containing microplastics in S1 were dried at 25°C;

[0053] The crushed soil sample in S1 was passed through a 5 mm coarse sieve for screening. 5 mm is the particle size defined for microplastics, and plastic bodies larger than 5 mm are not considered microplastics.

[0054] Based on the electrostatic separation principle experiment, this invention solves the problems existing in existing soil microplastic separation technologies, such as low sample recovery rate and integrity, strong soil destructiveness, complex operation process, and difficulty in large-scale application, and provides a non-destructive and highly efficient soil microplastic physical separation solution.

[0055] 1. The base box 11 and the heightened frame 12 provided in the present invention are both made of wood, and the number of heightened frames 12 is assembled, which can adjust the height of the sample pool 10. There is no need to customize containers of multiple specifications, saving raw materials and storage space. The outer side of the adsorption plate 21 is provided with a nylon coating to eliminate the risk of high-voltage leakage and avoid contamination of the sample. The support assembly provided can adjust the height of the adsorption plate 21, which is convenient for adjustment according to actual usage. The connecting handle 22 provided can be held by hand and installed through the support assembly, which is suitable for laboratory and field scenes;

[0056] 2. Electrostatic adsorption covers a wide range of microplastic particle sizes (millimeter to micron). Results show that a single use of the device in sandy loam soil removes approximately 15%-20% of microplastics, and after five consecutive uses, the removal rate can reach 70%-80%. Compared with traditional methods, the recovery rate is significantly increased by 80%. Through physical separation at room temperature and without the addition of reagents, the original form of microplastics and the natural structure of the soil are preserved. Electrostatic adsorption responds instantly, and a single separation takes only a few minutes, which is time-saving and efficient. Operation only requires electricity and no consumable materials. Compared with traditional methods, long-term use costs are reduced by 50%.

[0057] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A soil microplastic electrostatic separation device, characterized in that: include: A sample pool (10) is used to place a soil sample, wherein an electrostatic adsorption mechanism (20) is provided on one side of the sample pool (10), and the electrostatic adsorption mechanism (20) is connected to an electrostatic discharge generator (30) via a wire (31); The electrostatic adsorption mechanism (20) includes an adsorption plate (21) and a connecting handle (22). The adsorption plate (21) is arranged above the sample pool (10). One side of the adsorption plate (21) is connected to the connecting handle (22). One end of the wire (31) passes through the connecting handle (22) and is electrically connected to the adsorption plate (21). The adsorption plate (21) is configured as a plate capable of generating static electricity when energized.

2. The soil microplastic electrostatic separation device according to claim 1, characterized in that: The adsorption plate (21) is configured as an aluminum plate with a nylon coating on the outside.

3. The soil microplastic electrostatic separation device according to claim 2, characterized in that: The connecting handle (22) is made of insulating material.

4. The soil microplastic electrostatic separation device according to claim 3, characterized in that: The electrostatic adsorption mechanism (20) further comprises a support assembly, which is connected to the connecting handle (22) and is used for installing the connecting handle (22) and the adsorption plate (21) and adjusting their heights.

5. The soil microplastic electrostatic separation device according to claim 4, characterized in that: The support assembly includes a support base (23), a support rod (24) and a locking piece (25). The support base (23) is provided on one side of the sample pool (10), and the upper end of the support base (23) is connected to the support rod (24). A mounting hole matching the support rod (24) is provided inside one end of the connecting handle (22), and the locking piece (25) is also provided on the support rod (24).

6. The soil microplastic electrostatic separation device according to claim 5, characterized in that: The locking member (25) includes two sets of locking nuts, and the support rod (24) is threadedly connected with the two sets of locking nuts, and the two sets of locking nuts are respectively located at the upper and lower ends of the mounting hole.

7. The soil microplastic electrostatic separation device according to claim 6, characterized in that: The sample pool (10) comprises a bottom box (11) and several groups of heightened frames (12), wherein the bottom box (11) is configured as a box structure with an upper end open, and the heightened frames (12) are configured as a box structure with upper and lower ends open. The heightened frames (12) are mounted on the upper end of the bottom box (11), and the upper ends of the heightened frames (12) and the upper ends of the heightened frames (12) are both provided with card blocks, and the lower ends of the heightened frames (12) are provided with card slots matched with the card blocks, and two groups of the heightened frames (12) are assembled by respectively matching the card blocks and the card slots.

8. A separation method using the soil microplastic electrostatic separation device according to claim 7, characterized in that: The following steps are involved: S1. Soil sample pretreatment: First, the collected soil samples containing microplastics are dried, then fully crushed to destroy large aggregates, and then sieved to remove large impurities for standby use; S2, electrostatic separation of microplastics, the soil sample after pretreatment is spread into the sample pool (10), the soil sample is laid at a height flush with the upper edge of the sample pool (10), the height of the adsorption plate (21) is adjusted so that the adsorption plate (21) is placed parallel to the sample pool (10) at 0.5 cm above the adsorption plate (21), the wire (31) is connected to the negative electrode of the electrostatic discharge generator (30), and the adsorption plate (21) is energized so that the adsorption plate (21) electrostatically adsorbs the microplastics in the soil sample spread into the sample pool (10) under the action of static electricity, so that the microplastics are separated from the soil sample; S3. Collection of microplastic samples. After the electrostatic discharge generator (30) is turned on, the microplastics in the soil sample are adsorbed onto the electrostatic adsorption plate (21) under the action of electrostatic attraction, and then the microplastic samples on the electrostatic adsorption plate (21) are swept and recovered using an electrostatic dust removal brush.

9. A separation method using the soil microplastic electrostatic separation device according to claim 8, characterized in that: The soil sample containing microplastics in S1 was dried at 25°C; The soil sample after crushing in S1 was passed through a 5 mm coarse sieve.

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