Micro-plastic circulating filtration and extraction device and method

Abstract

The microplastic circulating filtration and extraction device comprises a first bottle, a second bottle, a filter cartridge, a pneumatic switch and a vacuum pump, the top end of the first bottle is provided with a feeding port, the second bottle is located below the first bottle, and a first pipe is arranged between the top end of the second bottle and the bottom end of the first bottle; a first pipe is arranged between the bottom end of the second bottle and the top end of the first bottle, a second pipe is arranged between the bottom end of the second bottle and the top end of the first bottle, the first pipe is provided with a first valve, the second pipe is provided with a second valve, the filter cartridge is arranged on the first pipe, a first filter membrane is arranged in the filter cartridge, the pneumatic switch is arranged on the first bottle, and the vacuum pump is communicated with the top end of the first bottle and the top end of the second bottle. And the pneumatic switch seals the feeding hole under the action of negative pressure in the first bottle. Circulating filtration of the soil solution can be achieved through one vacuum pump, the situation that in the prior art, micro-plastic is prone to adhering to the reflux pump can be avoided, micro-plastic extraction and detection are more accurate, and the situation that in the prior art, the soil solution easily corrodes the reflux pump can be avoided.

Description

Technical Field

[0001] This application relates to the field of microplastic extraction technology, and in particular to a microplastic circulating filtration extraction device and method. Background Technology

[0002] Accurately detecting the microplastic content in soil samples is crucial for assessing the degree of microplastic pollution in soil and for better remediation of soil microplastic pollution. Related technologies involve adding a solution such as salt to the soil, then pouring the soil solution into a filter cartridge. The solution is filtered through a membrane inside the cartridge, where most microplastics are intercepted. The remaining solution and a small amount of microplastics pass through the membrane and are pumped back into the filter cartridge via a reflux pump, achieving a circulating filtration process for better microplastic extraction.

[0003] However, in the existing technology, the reflux pump is in direct contact with the soil solution, and some microplastics are easy to adhere to the reflux pump, affecting the extraction of microplastics. In addition, some soil solution is also easy to corrode the reflux pump, and the reflux pump needs to be cleaned after each use, which is inconvenient. Summary of the Invention

[0004] This application aims to address at least one of the technical problems existing in the prior art. To this end, this application proposes a microplastic circulating filtration extraction device, which can achieve circulating filtration of soil solution using a vacuum pump. This avoids the problem of microplastics easily adhering to the return pump in the prior art, making microplastic extraction and detection more accurate, and also avoids the problem of soil solution easily corroding the return pump in the prior art.

[0005] This application also proposes a method for microplastic cyclic filtration extraction.

[0006] The microplastic circulating filtration extraction device according to the first aspect of this application includes a first bottle, a second bottle, a filter cartridge, a pneumatic switch, and a vacuum pump. The first bottle has a feed inlet at its top. The second bottle is located below the first bottle. A first tube is provided between the top of the second bottle and the bottom of the first bottle. A second tube is provided between the bottom of the second bottle and the top of the first bottle. The first tube has a first valve, and the second tube has a second valve. The filter cartridge is located in the first tube and contains a first filter membrane. The pneumatic switch is located in the first bottle. The vacuum pump connects the top of the first bottle and the top of the second bottle. When the vacuum pump evacuates the first bottle, the pneumatic switch closes the feed inlet under the negative pressure inside the first bottle.

[0007] The microplastic circulating filtration extraction device according to the embodiments of this application has at least the following beneficial effects: Soil solution is added to the first bottle through the inlet. Then, the first valve is opened and the second valve is closed. A vacuum pump then evacuates the second bottle, causing the soil solution to pass through the first filter membrane of the filter cartridge under the combined action of the vacuum pump and gravity. The second valve is then opened and the first valve closed. The vacuum pump then evacuates the first bottle again, and a pneumatic switch closes the inlet under negative pressure. The vacuum pump continues to evacuate the first bottle, allowing the soil solution from the second bottle to enter the first bottle. This process is repeated until the microplastics filtered through the first filter membrane are removed. In this application, a single vacuum pump enables the circulating filtration of the soil solution, avoiding the problem of microplastics easily adhering to the return pump in existing technologies. This results in more accurate microplastic extraction and detection, and also avoids the corrosion of the return pump by the soil solution, eliminating the need for pump cleaning and making it convenient to use. In addition, the pneumatic switch can seal the feed, making the vacuum pump more effective at evacuating the first bottle. Moreover, the pneumatic switch can directly seal the feed port under the negative pressure inside the first bottle the moment the vacuum pump evacuates the first bottle, without the need for manual operation or controller control, making it more convenient to use.

[0008] According to some embodiments of this application, the pneumatic switch includes a base and a sealing plate. The base is detachably inserted into the feed inlet. The base is provided with an air duct connecting the feed inlet and the outside. A partition is provided inside the air duct, and the partition is provided with a through hole. The sealing plate is located on the side of the partition away from the feed inlet. The vacuum pump connects the air duct to the side of the partition away from the sealing plate. When the vacuum pump evacuates the air duct, the sealing plate adheres to the partition under negative pressure and blocks the through hole.

[0009] According to some embodiments of this application, the partition is provided with a mounting hole, the sealing plate is provided with a guide portion, and a guide cylinder is provided on the side of the partition away from the sealing plate. The guide portion passes through the mounting hole and extends into the guide cylinder. An elastic element is provided inside the guide cylinder. The elastic element abuts against the guide portion and is used to separate the sealing plate from the partition.

[0010] According to some embodiments of this application, the guide cylinder has a detachable cover plate on the side opposite to the partition, and the elastic element abuts against the cover plate.

[0011] According to some embodiments of this application, a plurality of through holes are provided, and the plurality of through holes are arranged circumferentially along the guide cylinder.

[0012] According to some embodiments of this application, a feeding cylinder is also included, the feeding cylinder including a cylinder body, a cover body and a second filter membrane, the cylinder body being connected to the vacuum pump, the cover body being detachably disposed on the cylinder body, a third valve being provided between the cover body and the side of the filter cylinder near the first bottle, the second filter membrane being sandwiched between the cylinder body and the cover body, wherein the first valve is disposed between the filter cylinder and the first bottle.

[0013] According to some embodiments of this application, the inner peripheral wall of the cylinder is provided with an annular recess, the inner peripheral wall of the annular recess is threadedly connected to the cover, the edge of the second filter membrane is provided with a sealing ring surrounding the second filter membrane, a first sealing ring is clamped between the sealing ring and the cover, and a second sealing ring is clamped between the sealing ring and the bottom surface of the annular recess.

[0014] According to some embodiments of this application, the top of the second bottle is provided with an air inlet pipe, and the air inlet pipe is provided with a fourth valve.

[0015] According to some embodiments of this application, a water outlet assembly is also included. The water outlet assembly includes a housing and an impeller. The housing is disposed in the second pipe and located below the second bottle. A liquid outlet pipe is provided at the bottom end of the housing. The liquid outlet pipe is provided with a fifth valve. The impeller is rotatably installed in the housing. When the solution passes through the housing, it drives the impeller to rotate.

[0016] According to the microplastic circulating filtration extraction method of the second aspect of this application, and based on the microplastic circulating filtration extraction apparatus of the first aspect of this application, the method includes: S100. Add soil solution into the first bottle through the feed inlet; S200: Open the first valve and close the second valve; S300, The vacuum pump evacuates the second bottle, so that the soil solution enters the second bottle after being filtered through the first filter membrane of the filter cartridge; S400: Open the second valve and close the first valve; S500, the vacuum pump evacuates the first bottle, the pneumatic switch closes the feed port under negative pressure, and the vacuum pump continues to evacuate the first bottle, so that the soil solution in the second bottle enters the first bottle; S600, repeat steps S200 to S500, and finally remove the microplastics filtered by the first filter membrane.

[0017] Additional aspects and advantages of this application will be set forth in part in the description which follows, and some of these additional aspects and advantages will become apparent from the description or may be learned by practice of this application. Attached Figure Description

[0018] The present application will be further described below with reference to the accompanying drawings and embodiments, wherein: Figure 1 This is a schematic diagram of a microplastic circulating filtration and extraction device. Figure 2 This is a cross-sectional view of a pneumatic switch; Figure 3 This is a cross-sectional view of the water outlet assembly; Figure 4 This is a cross-sectional view of the material handling cylinder.

[0019] Icon labels: The first bottle is 100; Second bottle 200; First tube 201; Second tube 202; First valve 203; Second valve 204; Inlet pipe 205; Fourth valve 206; Filter cartridge 300; Pneumatic switch 400; base 401; air duct 402; partition 403; through hole 404; sealing plate 405; mounting hole 406; guide part 407; guide cylinder 408; elastic element 409; cover plate 410; Vacuum pump 500; Feeding cylinder 600; cylinder body 601; cover body 602; third valve 603; second filter membrane 604; annular settling platform 605; sealing ring 606; first sealing ring 607; second sealing ring 608; Water outlet assembly 700; tank 701; liquid outlet pipe 702; fifth valve 703; impeller 704. Detailed Implementation

[0020] The embodiments of this application are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0021] In the description of this application, it should be understood that the orientation descriptions, such as up, down, etc., are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0022] In the description of this application, "multiple" refers to two or more. The use of "first" and "second" is for the purpose of distinguishing technical features only and should not be construed as indicating or implying relative importance, or implicitly indicating the number of technical features indicated, or the order in which the technical features are indicated.

[0023] In the description of this application, unless otherwise expressly defined, terms such as "setup," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this application in conjunction with the specific content of the technical solution.

[0024] The following is for reference. Figures 1 to 4 This application describes a microplastic circulating filtration extraction apparatus and method according to embodiments of the present application.

[0025] refer to Figures 1 to 4 As shown, the microplastic circulating filtration extraction device according to the first aspect of this application includes a first bottle 100, a second bottle 200, a filter cartridge 300, a pneumatic switch 400, and a vacuum pump 500.

[0026] The first bottle 100 has a feed inlet at its top. The feed inlet is used to add soil solution into the first bottle 100. The soil solution is formed by adding salt solutions such as sodium chloride solution to the soil and then stirring and mixing it.

[0027] The second bottle 200 is located below the first bottle 100. A first pipe 201 is provided between the top of the second bottle 200 and the bottom of the first bottle 100, and a second pipe 202 is provided between the bottom of the second bottle 200 and the top of the first bottle 100. The first pipe 201 is equipped with a first valve 203, and the second pipe 202 is equipped with a second valve 204. For example, the first valve 203 and the second valve 204 can be shut-off valves. Because the second bottle 200 is located below the first bottle 100, when the first valve 203 is open and the second valve 204 is closed, the soil solution in the first bottle 100 can flow relatively slowly into the second bottle 200 under its own gravity.

[0028] A filter cartridge 300 is disposed in the first tube 201, and a first filter membrane is disposed inside the filter cartridge 300. For example, the first filter membrane can be horizontally disposed, and the section of the first tube 201 between the filter cartridge 300 and the first bottle 100 can be connected to the top end of the filter cartridge 300, and the section of the first tube 201 between the filter cartridge 300 and the second bottle 200 can be connected to the bottom end of the filter cartridge 300.

[0029] Vacuum pump 500 is connected to the top of the first bottle 100 and the top of the second bottle 200. It should be noted that vacuum pump 500 can evacuate the top of the first bottle 100 and the top of the second bottle 200 independently. That is, when vacuum pump 500 evacuates the top of the first bottle 100, vacuum pump 500 is isolated from the top of the second bottle 200, and when vacuum pump 500 evacuates the top of the second bottle 200, vacuum pump 500 is isolated from the top of the first bottle 100.

[0030] The pneumatic switch 400 is installed in the first bottle 100. When the vacuum pump 500 evacuates the first bottle 100, the pneumatic switch 400 closes the feed inlet under the negative pressure inside the first bottle 100. It should be noted that closing the feed inlet mentioned in this application means cutting off the connection between the feed inlet and the outside.

[0031] Soil solution is added into the first bottle 100 through the inlet. Then, the first valve 203 is opened and the second valve 204 is closed. The vacuum pump 500 then evacuates the second bottle 200, causing the soil solution to pass through the first filter membrane of the filter cartridge 300 under the action of the vacuum pump 500 and its own gravity before entering the second bottle 200. Then, the second valve 204 is opened and the first valve 203 is closed. The vacuum pump 500 then evacuates the first bottle 100. The pneumatic switch 400 closes the inlet under negative pressure. The vacuum pump 500 continues to evacuate the first bottle 100, causing the soil solution in the second bottle 200 to enter the first bottle 100. The previous steps are repeated. Finally, the microplastics filtered through the first filter membrane are removed.

[0032] In this application, the circulation and filtration of the soil solution can be achieved using a single vacuum pump 500, avoiding the problem of microplastics easily adhering to the return pump in existing technologies. This results in more accurate microplastic extraction and detection, and also avoids the corrosion of the return pump by the soil solution, eliminating the need for pump cleaning and making it convenient to use. Furthermore, the pneumatic switch 400 can seal the feed inlet, improving the vacuum pump 500's vacuuming effect on subsequent bottles 100. Moreover, the pneumatic switch 400 can directly seal the feed inlet under the negative pressure within the first bottle 100 the moment the vacuum pump 500 evacuates it, without requiring manual operation or a controller, making it even more convenient to use.

[0033] refer to Figure 2 As shown, in some embodiments of this application, the pneumatic switch 400 includes a base 401 and a sealing plate 405. The base 401 is detachably inserted into the feed inlet. For example, the bottom end of the base 401 may have a connector with a stepped top surface. The connector is inserted into the feed inlet and can be interference-fitted with the feed inlet to achieve a sealed connection with the feed inlet of the first bottle 100. The base 401 has an air duct 402 connecting the feed inlet and the outside. The air duct 402 can extend vertically and has a partition 403 inside. The partition 403 can be horizontally arranged and has a through hole 404. The sealing plate 405 is located on the side of the partition 403 opposite to the feed inlet. The vacuum pump 500 connects the air duct 402 to the side of the partition 403 opposite to the sealing plate 405, thereby indirectly connecting to the first bottle 100. When vacuum pump 500 evacuates air duct 402, sealing plate 405 adheres to partition plate 403 under negative pressure, thus blocking through hole 404.

[0034] In this embodiment, when the vacuum pump 500 evacuates the top of the second bottle 200, although the soil solution in the first bottle 100 can flow into the second bottle 200, since the first bottle 100 is not directly evacuated, a negative pressure will not be formed directly inside the first bottle 100. Furthermore, since the second bottle 200 is located below the first bottle 100, the soil solution can flow by its own gravity. The vacuum pump 500 can evacuate with a smaller force, thus preventing a large negative pressure from forming instantly inside the first bottle 100. A gap can still exist between the sealing plate 405 and the partition plate 403, allowing air to be drawn from the outside through the gap between the sealing plate 405 and the partition plate 403. This allows the soil solution in the first bottle 100 to flow smoothly into the second bottle 200 after being filtered by the first filter membrane inside the filter cartridge 300.

[0035] When the vacuum pump 500 evacuates the air duct 402, it evacuates the air duct 402, which is very close to the through hole 404. This causes a large negative pressure to be formed at the through hole 404 instantly. Under the action of the large negative pressure, that is, under the action of the large suction, the sealing plate 405 can stick to the partition plate 403 and block the through hole 404, thereby sealing the feed inlet. The operation is very convenient.

[0036] refer to Figure 2 As shown, in some embodiments of this application, the partition 403 is provided with a mounting hole 406, the sealing plate 405 is provided with a guide portion 407, and a guide cylinder 408 is provided on the side of the partition 403 opposite to the sealing plate 405. The guide portion 407 passes through the mounting hole 406 and extends into the guide cylinder 408. An elastic member 409 is provided inside the guide cylinder 408. The elastic member 409 abuts against the guide portion 407 and is used to separate the sealing plate 405 from the partition 403. For example, the elastic member 409 can be a spring or an elastic rubber block, etc. The size of the portion of the guide portion 407 extending into the guide cylinder 408 can be larger than the size of the mounting hole 406, restricting the portion of the guide portion 407 extending into the guide cylinder 408 from moving out of the mounting hole 406.

[0037] In this embodiment, when the vacuum pump 500 evacuates the top of the second bottle 200, the negative pressure generated inside the first bottle 100 is very small. Under the elastic force of the elastic element 409, the sealing plate 405 can separate from the partition plate 403, creating a gap. This allows outside air to enter the first bottle 100, and the soil solution inside the first bottle 100 can flow smoothly into the second bottle 200 after being filtered by the first filter membrane in the filter cartridge 300. When the vacuum pump 500 evacuates the air duct 402, since the vacuum is being evacuated inside the air duct 402, it is very close to the through hole 404. This allows a large negative pressure to be instantly formed at the through hole 404. Under the action of the large negative pressure, the sealing plate 405 approaches the partition plate 403, thereby compressing the elastic element 409. After the sealing plate 405 adheres to the partition plate 403, it can seal the through hole 404, making the operation very convenient.

[0038] It should be noted that when the vacuum pump 500 does not evacuate the air duct 402, the sealing plate 405 can also be separated from the partition plate 403 in other ways. For example, the sealing plate 405 can also be an elastic sheet, and the sealing plate 405 can be separated from the partition plate 403 by its own elastic restoring force.

[0039] refer to Figure 2 As shown, in some embodiments of this application, a removable cover plate 410 is provided on the side of the guide cylinder 408 away from the partition plate 403, and an elastic member 409 abuts against the cover plate 410. For example, the cover plate 410 can be threaded to the guide cylinder 408 or connected by fasteners.

[0040] In this embodiment, the cover plate 410 is provided to reduce the communication between outside air and the first bottle 100 through the mounting hole 406 and the guide cylinder 408, thereby improving the negative pressure effect inside the first bottle 100. The cover plate 410 is detachable, facilitating the installation and removal of the elastic element 409.

[0041] refer to Figure 2 As shown, in some embodiments of this application, multiple through holes 404 are provided, and the multiple through holes 404 are arranged circumferentially along the guide cylinder 408.

[0042] In this embodiment, multiple through holes 404 are provided. This facilitates the entry of outside air into the first bottle 100 when the vacuum pump 500 evacuates the second bottle 200, allowing the soil solution in the first bottle 100 to flow smoothly into the second bottle 200 after being filtered by the first filter membrane in the filter cartridge 300. When the vacuum pump 500 evacuates the first bottle 100, the sealing effect of the sealing plate 405 on the through holes 404 is also improved.

[0043] refer to Figure 1 and Figure 4As shown, in some embodiments of this application, the microplastic circulating filtration extraction device further includes a feeding cylinder 600, which includes a cylinder body 601, a cover 602, and a second filter membrane 604. The cylinder body 601 is connected to a vacuum pump 500. The cover 602 is detachably disposed on the cylinder body 601. A third valve 603 is provided between the cover 602 and the side of the filter cylinder 300 near the first bottle 100. The second filter membrane 604 is sandwiched between the cylinder body 601 and the cover 602. The first valve 203 is disposed between the filter cylinder 300 and the first bottle 100. For example, the third valve 603 can be a shut-off valve. The cover 602 and the cylinder body 601 can be connected by threads or by fasteners. The position of the cylinder body 601 connected to the vacuum pump 500 and the position of the cover 602 connected to the first bottle 100 are respectively located on opposite sides of the second filter membrane 604. It should be noted that the vacuum pump 500 can evacuate the material taking cylinder 600 independently. That is, when the vacuum pump 500 evacuates the material taking cylinder 600, the vacuum pump 500 is isolated from the first bottle 100 and the second bottle 200. When evacuating the first bottle 100 or the second bottle 200, the vacuum pump 500 is isolated from the material taking cylinder 600.

[0044] Since the filter cartridge 300 needs to be supplied with soil solution and air frequently, it needs to be frequently used with the vacuum pump 500 for vacuuming. If the filter cartridge 300 is frequently disassembled to remove the microplastics on the first filter membrane, poor sealing may occur, affecting the delivery of soil solution and air, as well as affecting the vacuuming with the vacuum pump 500.

[0045] In this embodiment, after the soil solution is circulated and filtered, the filtered soil solution is drained, the first valve 203 is closed, and the vacuum pump 500 evacuates the material collection cylinder 600. This allows air to pass through the first filter membrane from the side near the second bottle 200 and then onto the side near the first bottle 100, before being drawn into the material collection cylinder 600. The flowing air carries the microplastics on the first filter membrane into the material collection cylinder 600. Afterwards, the cover 602 is removed, and the second filter membrane 604 and its microplastics are taken out, making material collection more convenient. Furthermore, it eliminates the need to disassemble the filter cylinder 300, resulting in better sealing. Secondly, during vacuuming, the flowing air also dries the microplastics on the first filter membrane, making it easier for them to separate from the first filter membrane and enter the material collection cylinder 600, and also easier to separate from the second filter membrane 604, further facilitating material collection. In addition, during vacuuming, the flowing air also performs backflushing and cleaning of the first filter membrane, reducing the possibility of clogging, thus providing multiple functions.

[0046] refer to Figure 4As shown, in some embodiments of this application, the inner peripheral wall of the cylinder 601 is provided with an annular recess 605, the inner peripheral wall of the annular recess 605 is threadedly connected to the cover 602, the edge of the second filter membrane 604 is provided with a sealing ring 606 surrounding the second filter membrane 604, a first sealing ring 607 is sandwiched between the sealing ring 606 and the cover 602, and a second sealing ring 608 is sandwiched between the sealing ring 606 and the bottom surface of the annular recess 605. For example, both the first sealing ring 607 and the second sealing ring 608 can be made of rubber or silicone.

[0047] In this embodiment, an annular recess 605 is provided, and the inner peripheral wall of the annular recess 605 is threadedly connected to the cover 602. The sealing ring 606 is provided with a first sealing ring 607 and a second sealing ring 608 on both sides of the thickness direction of the second filter membrane 604, which makes the sealing performance better, the vacuum pump 500 has a better vacuuming effect, and makes it easier for the microplastics in the filter cartridge 300 to enter the feed cylinder 600.

[0048] refer to Figure 1 As shown, in some embodiments of this application, the top of the second bottle 200 is provided with an air inlet pipe 205, and the air inlet pipe 205 is provided with a fourth valve 206. For example, the fourth valve 206 can be a shut-off valve.

[0049] In this embodiment, when the soil solution is circulated and filtered, the fourth valve 206 is closed. When the vacuum pump 500 evacuates the material collection cylinder 600, the fourth valve 206 is opened, allowing outside air to enter the filter cylinder 300. This makes it easier for the microplastics in the filter cylinder 300 to enter the material collection cylinder 600, and also makes it easier to dry the microplastics on the first filter membrane. In addition, the backflushing cleaning effect on the first filter membrane is better.

[0050] refer to Figure 1 and Figure 3 As shown, in some embodiments of this application, the microplastic circulating filtration extraction device further includes a water outlet assembly 700. The water outlet assembly 700 includes a housing 701 and an impeller 704. The housing 701 is disposed within the second pipe 202 and located below the second bottle 200. A liquid outlet pipe 702 is provided at the bottom end of the housing 701, and the liquid outlet pipe 702 is equipped with a fifth valve 703. The impeller 704 is rotatably mounted inside the housing 701, and the impeller 704 rotates when the solution passes through the housing 701. For example, the section of the second pipe 202 between the housing 701 and the second bottle 200 can extend downwards at an angle close to the housing 701 or extend vertically downwards. The fifth valve 703 can be a shut-off valve.

[0051] In this embodiment, during the circulating filtration of the soil solution, the fifth valve 703 is closed, and the soil solution in the second bottle 200 enters the chamber 701, and then enters the first bottle 100. As the solution passes through the chamber 701, it drives the impeller 704 to rotate, preventing microplastics from settling in the chamber 701 and improving the circulating filtration effect of microplastics. After the soil solution circulation filtration is completed, the fifth valve 703 is opened to discharge the soil solution.

[0052] The microplastic circulating filtration extraction method according to the second aspect of this application, and the microplastic circulating filtration extraction apparatus according to the first aspect of this application, include, but are not limited to, the following steps: S100, add soil solution into the first bottle 100 through the inlet; S200, Open the first valve 203 and close the second valve 204; S300 and vacuum pump 500 evacuate the second bottle 200, so that the soil solution enters the second bottle 200 after being filtered through the first filter membrane of filter cartridge 300. S400, Open the second valve 204 and close the first valve 203; S500 and vacuum pump 500 evacuate the first bottle 100. Pneumatic switch 400 closes the feed inlet under negative pressure. Vacuum pump 500 continues to evacuate the first bottle 100, allowing the soil solution in the second bottle 200 to enter the first bottle 100. S600, repeat steps S200 to S500, and finally remove the microplastics filtered by the first filter membrane.

[0053] In this embodiment, the circulation and filtration of the soil solution can be achieved using a single vacuum pump 500. This avoids the problem of microplastics easily adhering to the return pump in existing technologies, resulting in more accurate microplastic extraction and detection. It also avoids the issue of soil solution easily corroding the return pump, a problem present in existing technologies. Furthermore, the pneumatic switch 400 can seal the feed inlet, improving the vacuum pump 500's subsequent vacuuming effect on the first bottle 100. Moreover, the pneumatic switch 400 can directly seal the feed inlet under the negative pressure within the first bottle 100 the instant the vacuum pump 500 evacuates it, without requiring manual operation or a controller, making it more convenient to use.

[0054] The embodiments of this application have been described in detail above with reference to the accompanying drawings. However, this application is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of this application.

Claims

1. A microplastic circulating filtration extraction device, characterized in that, include: The first bottle has a feed inlet at its top; The second bottle is located below the first bottle. A first tube is provided between the top of the second bottle and the bottom of the first bottle, and a second tube is provided between the bottom of the second bottle and the top of the first bottle. The first tube is equipped with a first valve, and the second tube is equipped with a second valve. A filter cartridge is disposed in the first tube, and a first filter membrane is disposed inside the filter cartridge; A pneumatic switch is located on the first bottle; A vacuum pump connects the top of the first bottle to the top of the second bottle; When the vacuum pump evacuates the first bottle, the pneumatic switch closes the feed port under the negative pressure inside the first bottle.

2. The microplastic circulating filtration extraction device according to claim 1, characterized in that, The pneumatic switch includes: The base is detachably inserted into the feed inlet. The base is provided with an air duct connecting the feed inlet and the outside. The air duct is provided with a partition and the partition is provided with a through hole. A sealing plate is provided on the side of the partition away from the feed inlet; The vacuum pump is connected to the air duct on the side of the partition away from the sealing plate. When the vacuum pump evacuates the air duct, the sealing plate adheres to the partition under negative pressure and blocks the through hole.

3. The microplastic circulating filtration extraction device according to claim 2, characterized in that, The partition plate has a mounting hole, the sealing plate has a guide portion, and the partition plate has a guide cylinder on the side opposite to the sealing plate. The guide portion passes through the mounting hole and extends into the guide cylinder. An elastic element is provided inside the guide cylinder. The elastic element abuts against the guide portion and is used to separate the sealing plate from the partition plate.

4. The microplastic circulating filtration extraction device according to claim 3, characterized in that, The guide cylinder has a detachable cover plate on the side opposite to the partition, and the elastic element abuts against the cover plate.

5. The microplastic circulating filtration extraction device according to claim 3, characterized in that, The through holes are provided in multiple ways, and the multiple through holes are arranged circumferentially along the guide cylinder.

6. The microplastic circulating filtration extraction device according to claim 1, characterized in that, It also includes a material receiving cylinder, the material receiving cylinder comprising: The cylinder is connected to the vacuum pump; A cap is detachably disposed on the cylinder, and a third valve is provided between the cap and the side of the filter cylinder near the first bottle; The second filter membrane is sandwiched between the cylinder and the cover. The first valve is located between the filter cartridge and the first bottle.

7. The microplastic circulating filtration extraction device according to claim 6, characterized in that, The inner circumferential wall of the cylinder is provided with an annular recess, the inner circumferential wall of the annular recess is threadedly connected to the cover, the edge of the second filter membrane is provided with a sealing ring surrounding the second filter membrane, a first sealing ring is clamped between the sealing ring and the cover, and a second sealing ring is clamped between the sealing ring and the bottom surface of the annular recess.

8. The microplastic circulating filtration extraction device according to claim 1, characterized in that, The second bottle has an air inlet pipe at the top, and the air inlet pipe has a fourth valve.

9. The microplastic circulating filtration extraction device according to claim 1, characterized in that, It also includes a water outlet assembly, which comprises: A box body is provided on the second tube and located below the second bottle. The bottom end of the box body is provided with a liquid outlet pipe, and the liquid outlet pipe is provided with a fifth valve. An impeller is rotatably installed inside the tank, and the impeller rotates as the solution passes through the tank.

10. A method for microplastic circulating filtration extraction, based on the microplastic circulating filtration extraction device according to claim 1, characterized in that, include: S100. Add soil solution into the first bottle through the feed inlet; S200: Open the first valve and close the second valve; S300, The vacuum pump evacuates the second bottle, so that the soil solution enters the second bottle after being filtered through the first filter membrane of the filter cartridge; S400: Open the second valve and close the first valve; S500, the vacuum pump evacuates the first bottle, the pneumatic switch closes the feed port under negative pressure, and the vacuum pump continues to evacuate the first bottle, so that the soil solution in the second bottle enters the first bottle; S600, repeat steps S200 to S500, and finally remove the microplastics filtered by the first filter membrane.

Images