Device and method for separating and simulating horizontal migration of microplastics with different particle sizes in water body

Abstract

The invention discloses a device and method for separating and simulating horizontal migration of microplastics with different particle sizes in a water body, the device comprises a water inlet, a primary filter layer, a digestion column and a flotation layer which are arranged in sequence, an impurity filter screen is arranged between the primary filter layer and the water inlet, and a turnover filter screen is arranged in the primary filter layer; a pretreatment rotating nozzle is arranged at the lateral upper part of the primary filtering layer and is positioned above the turnover filter screen, a first waste liquid cylinder and a first waste liquid cylinder control valve connected with the first waste liquid cylinder are arranged on one side of the bottom of the primary filtering layer, and waste liquid flows through the first waste liquid cylinder control valve and enters the first waste liquid cylinder; a first valve is arranged between the primary filtering layer and the digestion column. According to the invention, pretreatment of detection of micro-plastics in a water body is integrated in one device, so that the micro-plastics with different particle sizes can be separated at the same time, and horizontal migration simulation of the micro-plastics with different particle sizes can be completed; and various operations of pretreatment can be simplified, the loss and collection error of the micro-plastic are reduced, and an integrated collection and simulation process is realized.

Description

Technical Field

[0001] The invention relates to a device and method for separating and simulating the horizontal migration of microplastics with different particle sizes in water bodies, belonging to the technical field of microplastic separation and collection. Background Art

[0002] Plastic products have good chemical stability, strong plasticity and low cost, and have been widely used in life and production. Plastic waste accumulated in the environment can be decomposed into tiny plastic particles under physical, chemical and biological effects. Microplastics refer to plastic particles with a particle size of less than 5mm. At present, the abundance of microplastics in the environment has reached a level that cannot be ignored. Due to the characteristics of microplastics such as wide sources, small size and easy migration, they are widely present in various water environments. Therefore, the potential ecological risks that may be caused by microplastics need to be taken seriously.

[0003] In order to study the abundance and occurrence of microplastics in water bodies, it is necessary to conduct a systematic field survey and detect microplastics in water bodies by collecting water samples. However, the current pretreatment of microplastic detection is relatively complicated, requiring filtration, digestion and flotation. These pretreatments require different devices and equipment, and the operation is relatively cumbersome. Microplastics are easily lost or contaminated during the liquid transfer process of different operations. At the same time, the horizontal migration of microplastics in water bodies involves their occurrence in natural water bodies, which is currently less studied, and the simulation of the horizontal migration process deserves further study.

[0004] In summary, the devices in the prior art are unable to simultaneously separate microplastics of different particle sizes and complete the horizontal migration simulation of microplastics of different particle sizes. There are problems such as microplastic loss and collection errors. In addition, the operation is cumbersome and it is impossible to achieve an integrated collection and simulation process. Summary of the invention

[0005] To solve the above problems, the present invention provides a device and method for separating and simulating the horizontal migration of microplastics of different particle sizes in water bodies. The present invention concentrates the pretreatment of microplastic detection in water bodies in one device, can simultaneously separate microplastics of different particle sizes and complete the simulation of the horizontal migration of microplastics of different particle sizes; and can simplify various pretreatment operations, reduce the loss and collection errors of microplastics, and realize an integrated collection and simulation process.

[0006] The first object of the present invention is to provide a device for separating the horizontal migration of microplastics of different particle sizes in simulated water bodies, comprising a water inlet, a primary filter layer, a digestion column and a flotation layer arranged in sequence from top to bottom, an impurity filter screen is arranged between the primary filter layer and the water inlet, a reversible filter screen is arranged in the primary filter layer, a pretreatment rotary nozzle is arranged on the upper side of the primary filter layer, and the pretreatment rotary nozzle is located above the reversible filter screen, a first waste liquid tank and a first waste liquid tank control valve connected thereto are arranged on one side of the bottom of the primary filter layer, and the waste liquid flows through the first waste liquid tank control valve into the first waste liquid tank; a first valve is arranged between the primary filter layer and the digestion column.

[0007] In one embodiment of the present invention, the digestion column is connected below the primary filtration layer to receive flushing liquid containing microplastics from the primary filtration layer. The digestion column is detachably connected to the primary filtration layer and the flotation layer, and digestion liquid is added to the digestion column.

[0008] In one embodiment of the present invention, a liquid adding port is provided on one side of the top of the flotation layer, a second waste liquid tank and a second waste liquid tank control valve connected thereto are provided on one side of the bottom, the waste liquid flows through the second waste liquid tank control valve into the second waste liquid tank, and a second valve is provided inside the flotation layer; flotation liquid is added from the liquid adding port to float the digestion liquid, and after the liquid is separated, the lower layer of liquid is passed into the second waste liquid tank to obtain a supernatant containing microplastics.

[0009] In one embodiment of the present invention, the flotation layer is an L-shaped structure, the upper end of the L-shaped structure is arranged vertically and connected to the digestion column, and the lower end of the L-shaped structure is arranged horizontally and is the microplastic collection area of ​​the microplastic collection and separation mechanism; the microplastic collection area at the lower end of the flotation layer is sequentially provided with a first filter screen, a second filter screen, and a third filter screen with decreasing mesh apertures, and the first filter screen, the second filter screen, and the third filter screen are respectively used to collect large-particle microplastics, medium-particle microplastics and small-particle microplastics; a first filter control valve is arranged on the pipe connected to the bottom of the first filter screen, and a first water inlet control valve is arranged on the side of the first filter screen away from the second filter screen; a second filter control valve is arranged on the pipe connected to the bottom of the second filter screen, and a second water inlet control valve is arranged on the side of the second filter screen facing the first filter screen; a third filter control valve is arranged on the pipe connected to the bottom of the third filter screen, and a third water inlet control valve is arranged on the side of the third filter screen facing the second filter screen.

[0010] In one embodiment of the present invention, a collecting area rotating nozzle is provided on the side of the first filter screen facing the second filter screen, the side of the second filter screen facing the third filter screen, and the side of the third filter screen away from the second filter screen, and the collecting area rotating nozzle is connected to the second high-pressure liquid replenishment flusher; the lower end of the flotation layer is connected to the third waste liquid tank through a pipeline.

[0011] In one embodiment of the present invention, a third water outlet control valve is arranged between the pipe connected to the bottom of the first filter screen and the pipe connected to the third waste liquid tank; a second water outlet control valve is arranged between the pipe connected to the bottom of the second filter screen and the pipe connected to the third waste liquid tank; a first water outlet control valve is arranged between the pipe connected to the bottom of the third filter screen and the pipe connected to the third waste liquid tank; a separation zone control valve is arranged between the pipe connected to the third waste liquid tank and the right end of the third filter screen.

[0012] In one embodiment of the present invention, the pipe connected to the bottom of the first filter screen, the pipe connected to the bottom of the second filter screen, and the pipe connected to the bottom of the third filter screen are all L-shaped structures, the upper ends of which are arranged vertically and connected to the flotation layer, and the lower ends are arranged horizontally and are horizontal migration simulation areas, the horizontal migration simulation area is provided with a plurality of sampling water inlets and a water inlet control valve located on one side of the water inlet; the sampling water inlet is connected to a suction filtration device, and the suction filtration device is provided with a mixed fiber filter membrane.

[0013] In one embodiment of the present invention, the pretreatment rotary nozzle is externally connected to a first high-pressure liquid replenishment flusher, and the first high-pressure liquid replenishment flusher is provided with a linkage switch.

[0014] The second object of the present invention is to provide a method for separating and simulating the horizontal migration of microplastics of different particle sizes in water, using the device for separating and simulating the horizontal migration of microplastics of different particle sizes in water, comprising the following steps:

[0015] Step 1: Add sample and filter initially; collect water sample and add it from the water inlet, large impurities are trapped on the impurity filter and removed, the water sample is filtered through the reversible filter, microplastics are trapped by the filter, close the first valve, open the first waste liquid cylinder control valve, and the remaining liquid enters the first waste liquid cylinder; close the first waste liquid cylinder control valve, use the pretreatment rotary nozzle to flush the reversible screen up and down, open the first valve, and flush the microplastics into the digestion column;

[0016] Step 2: digestion and flotation of microplastics; after the flushing liquid containing microplastics enters, the digestion column is disassembled from the device, the digestion liquid is added to the digestion column, and the column is placed in an oscillating incubator for digestion. After the digestion is completed, the integrated device is assembled; the second valve is closed to allow the digestion liquid to enter the flotation layer, and a saturated sodium chloride solution is added to the liquid adding port. After the flotation is allowed to stand, the second waste liquid cylinder control valve is opened to allow the lower layer of liquid to enter the second waste liquid cylinder, and the supernatant where the microplastics are gathered is retained; the second waste liquid cylinder control valve is closed, and the second valve is opened to allow the supernatant to enter the microplastic collection area;

[0017] Step 3: separation and collection of microplastics: Open the first water inlet control valve, the second water inlet control valve, and the third water inlet control valve, and the large-size microplastics, medium-size microplastics, and small-size microplastics are respectively retained on the first filter screen, the second filter screen, and the third filter screen, and the remaining liquid enters the third waste liquid tank along the pipeline;

[0018] Step 4: Simulate the migration of microplastics;

[0019] When simulating the horizontal migration of large-sized microplastics, close the first water inlet control valve, the second water inlet control valve and the first filter screen control valve, use the collection area rotary nozzle to flush the first filter screen up and down, open the first filter screen control valve, and allow the liquid carrying large-sized microplastics to enter the horizontal migration simulation area for horizontal migration. Select horizontal sampling outlets at different positions at the same time to sample for qualitative characterization and quantitative statistics of microplastics;

[0020] When simulating the horizontal migration of medium-sized microplastics, close the second water inlet control valve, the third water inlet control valve and the second filter screen control valve, use the collection area rotary nozzle to flush the second filter screen up and down, open the second filter screen control valve, and allow the liquid carrying medium-sized microplastics to enter the horizontal migration simulation area for horizontal migration. Select horizontal sampling outlets at different positions at the same time to take samples for qualitative characterization and quantitative statistics of microplastics;

[0021] When simulating the horizontal migration of small-sized microplastics, close the third water inlet control valve, the separation zone control valve and the third filter screen control valve, use the collection zone rotary nozzle to flush the third filter screen up and down, open the third filter screen control valve, and allow the liquid carrying small-sized microplastics to enter the horizontal migration simulation area for horizontal migration. Select horizontal sampling water outlets at different positions at the same time to take samples through the water intake control valve for qualitative characterization and quantitative statistics of microplastics;

[0022] Step 5. Record and conduct statistical analysis. Obtain water samples from the sampling inlet and connect them to the filtration device. The filtration device is equipped with a mixed fiber filter membrane. The water sample is filtered using the mixed fiber filter membrane. After the filter membrane is dried, it is placed in a glass culture dish. The glass culture dish is placed under a microscope for observation. The number of microplastics on the filter membrane in sampling at different positions is recorded. At the same time, the particle size of microplastics is divided into large-size microplastics, medium-size microplastics and small-size microplastics. Statistical analysis is performed on the microplastics on the filter membrane at different positions to derive the migration pattern of microplastics in the horizontal direction.

[0023] In one embodiment of the present invention, the digestion solution in step 2 is 200 mL of 30% hydrogen peroxide solution, which is placed in an oscillating incubator and digested for 48 hours at 80 rpm and 60°C; the saturated sodium chloride solution is added in a ratio of 6 g of sodium chloride per 20 mL of solution, and the second waste liquid tank control valve is opened after flotation is allowed to stand for 24 hours; the mixed fiber filter membrane in step 5 is 2 μm, the filter membrane drying time is 12 hours, and the microplastics on the filter membrane at different positions are statistically analyzed using software Image J; the particle size of large-particle microplastics is >2 mm, the particle size of medium-particle microplastics is 0.5-2 mm, and the particle size of small-particle microplastics is <0.5 mm.

[0024] The present invention has the following beneficial effects:

[0025] (1) The present invention can directly carry out an integrated pretreatment process in the device after obtaining the water sample, concentrate digestion, flotation and separation in one device for processing, simplify the pretreatment operation of microplastics, reduce the loss and collection error of microplastics, realize the integrated collection and simulation process, and can simultaneously separate microplastics of different particle sizes and complete the horizontal migration simulation of microplastics of different particle sizes, which is suitable for the study of the horizontal migration law of microplastics in water bodies. Specifically, after the water sample enters, a series of pretreatment processes can be completed in the device, and the pretreated water containing microplastics is separated and collected into microplastics of different particle sizes, and enters the corresponding parallel horizontal migration simulation pipeline to simulate the horizontal migration of microplastics. Through the present invention, the workload of separating and extracting microplastics in water bodies can be significantly reduced, and experimental data of simulated horizontal migration of microplastics of different particle sizes in water bodies can be obtained, with the advantages of high separation rate, convenient operation, and reusability.

[0026] (2) The present invention makes it easy for experimenters to separate water bodies and obtain experimental data on microplastics of different particle sizes. It has a high extraction rate, is easy to operate, and can be reused.

[0027] (3) After pre-treating the water sample, the present invention enriches the microplastics on the filter screens with different pore sizes, thus completing the separation and collection of the microplastics. The operation is convenient and reusable. After the separation and collection is completed, the horizontal migration of microplastics with different particle sizes can be simulated on this basis, further providing research on the migration and enrichment of microplastics in water bodies, which is convenient to operate and highly efficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. The drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0029] Figure 1 A schematic diagram of the structure of a device for separating and simulating the horizontal migration of microplastics of different particle sizes in water provided by the present invention;

[0030] Figure 2 A schematic diagram of the structure of the filter control valve, the sample water outlet and the water outlet control valve provided by the present invention;

[0031] Figure 3 The present invention provides a flow chart of a method for separating the horizontal migration of microplastics of different particle sizes in simulated water bodies.

[0032] Explanation of reference numerals: 1, water inlet; 2, primary filtration layer; 3, digestion column; 4, flotation layer; 5, impurity filter; 6, flip filter; 7, first filter; 8, second filter; 9, third filter; 10, first high-pressure liquid replenishment flusher; 11, pretreatment rotary nozzle; 12, second high-pressure liquid replenishment flusher; 13, liquid filling port; 14, first waste liquid tank; 15, first waste liquid tank control valve; 16, first valve; 17, second valve; 18, sample outlet; 19, linkage Switch; 20, first water inlet control valve; 21, second water inlet control valve; 22, third water inlet control valve; 23, first filter control valve; 24, second filter control valve; 25, third filter control valve; 26, first water outlet control valve; 27, second water outlet control valve; 28, third water outlet control valve; 29, separation zone control valve; 30, second waste liquid tank control valve; 31, second waste liquid tank; 32, third waste liquid tank; 33, collection zone rotary nozzle; 34, water intake control valve. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are 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 creative work are within the scope of protection of the present invention.

[0034] In the description of the present invention, it should be noted that the terms "upper", "lower", "inner", "outer", "top", "bottom" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0035] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0036] like Figure 1-2 As shown, an embodiment of the present invention provides a device for separating the horizontal migration of microplastics of different particle sizes in simulated water bodies. In some embodiments, the device includes a water inlet 1, a primary filter layer 2, a digestion column 3 and a flotation layer 4 arranged in sequence from top to bottom, an impurity filter screen 5 is arranged between the primary filter layer 2 and the water inlet 1, a reversible filter screen 6 is arranged in the primary filter layer 2, a pretreatment rotary nozzle 11 is arranged on the upper side of the primary filter layer 2, and the pretreatment rotary nozzle 11 is located above the reversible filter screen 6. The pretreatment rotary nozzle 11 is externally connected to a first high-pressure liquid infusion flusher 10, and the first high-pressure liquid infusion flusher 10 is provided with a linkage switch 19.

[0037] In some embodiments, a first waste liquid tank 14 and a first waste liquid tank control valve 15 connected thereto are provided on one side of the bottom of the primary filter layer 2, and the waste liquid flows through the first waste liquid tank control valve 15 into the first waste liquid tank 14; a first valve 16 is provided between the primary filter layer 2 and the digestion column 3.

[0038] The device for separating and simulating the horizontal migration of microplastics of different particle sizes in water provided in the embodiment of the present application collects water samples from the water inlet 1, and large impurities are filtered by the impurity filter 5. After the water sample is filtered by the reversible filter 6, the microplastics are intercepted by the reversible filter 6, so that the microplastics are enriched on the reversible filter 6. Close the first valve 16, open the first waste liquid cylinder control valve 15, and the remaining liquid enters the first waste liquid cylinder 14; close the first waste liquid cylinder control valve 15, use the pretreatment rotary nozzle 11 to flush the reversible filter 6 up and down, open the first valve 16, and flush the microplastics into the digestion column 3.

[0039] Optionally, the mesh size of the reversible filter 6 can be set to 2 μm.

[0040] In some embodiments, the digestion column 3 is connected to the bottom of the primary filtration layer 2 to receive the flushing liquid containing microplastics from the primary filtration layer 2. The digestion column 3 is detachably connected to the primary filtration layer 2 and the flotation layer 4, and is installed and connected after the digestion operation is completed. After the flushing liquid containing microplastics enters, the digestion column 3 is detached, and 200 mL of 30% hydrogen peroxide solution is added to the digestion column 3 as a digestion liquid, and the column is placed in an oscillating incubator for digestion at 80 rpm and 60°C for 48 hours. After the digestion is completed, the integrated device is assembled.

[0041] In some embodiments, a liquid adding port 13 is provided on one side of the top of the flotation layer 4, and a second waste liquid tank 31 and a second waste liquid tank control valve 30 connected thereto are provided on one side of the bottom. The waste liquid flows through the second waste liquid tank control valve 30 and enters the second waste liquid tank 31. A second valve 17 is provided inside the flotation layer 4. Flotation liquid is added from the liquid adding port 13 to float the digestion liquid. After the liquid is separated, the lower layer of liquid is passed into the second waste liquid tank 31 to obtain a supernatant containing microplastics.

[0042] Specifically, the second valve 17 is closed to allow the digestion solution to enter the flotation layer 4, and a saturated sodium chloride solution is added to the liquid adding port 13, wherein the ratio of the saturated sodium chloride solution is 6 g of sodium chloride for every 20 mL of solution. After the flotation is allowed to stand for 24 hours, the second waste liquid tank control valve 30 is opened to allow the lower layer of liquid to enter the second waste liquid tank 31, and the supernatant in which the microplastics are gathered is retained; the second waste liquid tank control valve 30 is closed, and the second valve 17 is opened to allow the supernatant to enter the microplastic collection area.

[0043] Optionally, the flotation layer 4 is an L-shaped structure, the upper end of the L-shaped structure is vertically arranged and connected to the digestion column 3, and the lower end of the L-shaped structure is horizontally arranged and is the microplastic collection area of ​​the microplastic collection and separation mechanism.

[0044] In some embodiments, the microplastic collection area at the lower end of the flotation layer 4 is provided with a first filter screen 7, a second filter screen 8, and a third filter screen 9 with decreasing mesh apertures in sequence, and the first filter screen 7, the second filter screen 8, and the third filter screen 9 are used to collect large-particle-size microplastics, medium-particle-size microplastics, and small-particle-size microplastics, respectively; a first filter screen control valve 23 is provided on the pipe connected to the lower part of the first filter screen 7, and a first water inlet control valve 20 is provided on the side of the first filter screen 7 facing away from the second filter screen 8; a second filter screen control valve 24 is provided on the pipe connected to the lower part of the second filter screen 8, and the second filter screen 8 faces the first filter screen 8. A second water inlet control valve 21 is provided on one side of the filter screen 7; a third filter screen control valve 25 is provided on the pipeline connected to the bottom of the third filter screen 9, and a third water inlet control valve 22 is provided on the side of the third filter screen 9 facing the second filter screen 8; a collecting area rotating nozzle 33 is provided on the side of the first filter screen 7 facing the second filter screen 8, the side of the second filter screen 8 facing the third filter screen 9, and the side of the third filter screen 9 away from the second filter screen 8, and the collecting area rotating nozzle 33 is connected to the second high-pressure liquid replenishment flusher 12; the lower end of the flotation layer 4 is connected to the third waste liquid tank 32 through a pipeline.

[0045] Open the first water inlet control valve 20, the second water inlet control valve 21, and the third water inlet control valve 22, and the large-size microplastics, medium-size microplastics, and small-size microplastics are respectively retained on the first filter screen 7, the second filter screen 8, and the third filter screen 9, and the remaining liquid enters the third waste liquid tank 32 along the pipeline. Optionally, the mesh of the first filter screen 7 can be set to 2mm; the mesh of the second filter screen 8 can be set to 0.5mm; the mesh of the third filter screen 9 can be set to 0.05mm. Among them, the first high-pressure liquid infusion flusher 10 and the second high-pressure liquid infusion flusher 12 can be controlled by the linkage switch 19.

[0046] Furthermore, a third water outlet control valve 28 is arranged between the pipe connected to the bottom of the first filter 7 and the pipe connected to the third waste liquid tank 32; a second water outlet control valve 27 is arranged between the pipe connected to the bottom of the second filter 8 and the pipe connected to the third waste liquid tank 32; a first water outlet control valve 26 is arranged between the pipe connected to the bottom of the third filter 9 and the pipe connected to the third waste liquid tank 32; and a separation zone control valve 29 is arranged between the pipe connected to the third waste liquid tank 32 and the right end of the third filter 9.

[0047] In some embodiments, the pipe connected to the bottom of the first filter screen 7, the pipe connected to the bottom of the second filter screen 8, and the pipe connected to the bottom of the third filter screen 9 are all L-shaped structures, whose upper ends are arranged vertically and connected to the flotation layer 4, and whose lower ends are arranged horizontally and are horizontal migration simulation areas. The horizontal migration simulation area is provided with several sampling water intakes 18 and a water intake control valve 34 located on one side of the water intake 18.

[0048] When simulating the horizontal migration of large-particle microplastics, close the first water inlet control valve 20, the second water inlet control valve 21 and the first filter screen control valve 23, use the collection area rotating nozzle 33 to flush the first filter screen 7 up and down, open the first filter screen control valve 23, and allow the liquid carrying large-particle microplastics to enter the horizontal migration simulation area for horizontal migration. Select the horizontal sampling outlet 18 at different positions at the same time to take samples for qualitative characterization and quantitative statistics of microplastics.

[0049] When simulating the horizontal migration of medium-sized microplastics, close the second water inlet control valve 21, the third water inlet control valve 22 and the second filter screen control valve 24, use the collection area rotating nozzle 33 to flush the second filter screen 8 up and down, open the second filter screen control valve 24, and allow the liquid carrying medium-sized microplastics to enter the horizontal migration simulation area for horizontal migration. Select the horizontal sampling outlet 18 at different positions at the same time to take samples for qualitative characterization and quantitative statistics of microplastics.

[0050] When simulating the horizontal migration of small-particle microplastics, close the third water inlet control valve 22, the separation zone control valve 29 and the third filter screen control valve 25, use the collection zone rotary nozzle 33 to flush the third filter screen 9 up and down, open the third filter screen control valve 25, and allow the liquid carrying small-particle microplastics to enter the horizontal migration simulation area for horizontal migration. Select the horizontal sampling water outlet 18 at different positions at the same time to take samples through the water outlet control valve 34 for qualitative characterization and quantitative statistics of microplastics.

[0051] When the sampling water inlet 18 is used to collect water samples, sampling and analysis are performed simultaneously at the sampling water inlets 18 at different horizontal positions. The sampling water inlet 18 is connected to a suction filtration device, and a 2μm mixed fiber filter membrane is set in the suction filtration device. The water sample is filtered using the mixed fiber filter membrane. After the filter membrane is dried for 12 hours, it is placed in a glass culture dish, and the glass culture dish is placed under a stereo microscope for observation at 60 times magnification; the number of microplastics on the filter membrane in sampling at different positions is recorded, and the particle size of microplastics is divided into large-particle microplastics (>2mm), medium-particle microplastics (0.5-2mm) and small-particle microplastics (<0.5mm). The software Image J is used to perform statistical analysis on the microplastics on the filter membrane at different positions to obtain the migration law of microplastics in the horizontal direction.

[0052] In addition, an embodiment of the present invention further provides a method for separating and simulating the horizontal migration of microplastics of different particle sizes in water, using the device for separating and simulating the horizontal migration of microplastics of different particle sizes in water, and the method comprises the following steps:

[0053] Step 1, adding sample and initial filtration; collecting water sample and adding it from the water inlet 1, large impurities and the like are trapped on the impurity filter 5 and removed, after the water sample is filtered through the reversible filter 6 2, microplastics are trapped by the filter, the first valve 16 is closed, the first waste liquid cylinder control valve 15 is opened, and the remaining liquid enters the first waste liquid cylinder 14; the first waste liquid cylinder control valve 15 is closed, and the reversible screen 6 is flushed up and down with the pretreatment rotary nozzle 11, and the first valve 16 is opened to flush the microplastics into the digestion column 3;

[0054] Step 2, digestion and flotation of microplastics; after the flushing liquid containing microplastics enters, the digestion column 3 is disassembled from the device, 200 mL of 30% hydrogen peroxide solution is added to the digestion column 3 as the digestion solution, and the digestion is placed in an oscillating incubator at 80 rpm and 60°C for 48 hours. After the digestion is completed, the integrated device is assembled; the second valve 17 is closed to allow the digestion solution to enter the flotation layer 4, and a saturated sodium chloride solution is added to the liquid adding port 13. The ratio of the saturated sodium chloride solution is 6 g of sodium chloride per 20 mL of solution. After the flotation is allowed to stand for 24 hours, the second waste liquid cylinder control valve 30 is opened to allow the lower layer of liquid to enter the second waste liquid cylinder 31, and the supernatant where the microplastics are gathered is retained; the second waste liquid cylinder control valve 30 is closed, and the second valve 17 is opened to allow the supernatant to enter the microplastic collection area;

[0055] Step 3: separation and collection of microplastics: opening the first water inlet control valve 20, the second water inlet control valve 21, and the third water inlet control valve 22, large-size microplastics, medium-size microplastics, and small-size microplastics are retained on the first filter screen 7, the second filter screen 8, and the third filter screen 9, respectively, and the remaining liquid enters the third waste liquid tank 32 along the pipeline;

[0056] Step 4: Simulate the migration of microplastics;

[0057] When simulating the horizontal migration of large-size microplastics, close the first water inlet control valve 20, the second water inlet control valve 21 and the first filter screen control valve 23, use the collection area rotating nozzle 33 to flush the first filter screen 7 up and down, open the first filter screen control valve 23, so that the liquid carrying large-size microplastics enters the horizontal migration simulation area for horizontal migration, and selects the horizontal sampling outlet 18 at different positions at the same time to sample for qualitative characterization and quantitative statistics of microplastics;

[0058] When simulating the horizontal migration of medium-sized microplastics, close the second water inlet control valve 21, the third water inlet control valve 22 and the second filter screen control valve 24, use the collection area rotary nozzle 33 to flush the second filter screen 8 up and down, open the second filter screen control valve 24, so that the liquid carrying medium-sized microplastics enters the horizontal migration simulation area for horizontal migration, and selects the horizontal sampling outlet 18 at different positions at the same time to sample for qualitative characterization and quantitative statistics of microplastics;

[0059] When simulating the horizontal migration of small-particle microplastics, close the third water inlet control valve 22, the separation zone control valve 29 and the third filter screen control valve 25, use the collection zone rotary nozzle 33 to flush the third filter screen 9 up and down, open the third filter screen control valve 25, so that the liquid carrying small-particle microplastics enters the horizontal migration simulation area for horizontal migration, and selects the horizontal sampling water inlet 18 at different positions at the same time to take samples through the water inlet control valve 34 for qualitative characterization and quantitative statistics of microplastics;

[0060] Step 5, record and conduct statistical analysis; obtain water samples from the sampling water inlet 18 and connect them to the filtration device. The filtration device is equipped with a 2μm mixed fiber filter membrane. The water sample is filtered using the mixed fiber filter membrane. After the filter membrane is dried for 12 hours, it is placed in a glass culture dish. The glass culture dish is placed under a stereo microscope and magnified 60 times for observation; the number of microplastics on the filter membrane in sampling at different positions is recorded; at the same time, the particle size of microplastics is divided into large-particle microplastics, medium-particle microplastics and small-particle microplastics; the software ImageJ is used to perform statistical analysis on the microplastics on the filter membrane at different positions to obtain the migration law of microplastics in the horizontal direction.

[0061] In summary, the present invention provides a device and method for separating and simulating the horizontal migration of microplastics of different particle sizes in water bodies. The collected water samples are first pretreated, and then the horizontal migration of microplastics in the water samples to be tested is simulated after pretreatment, and the samples are collected for research and analysis.

[0062] Pretreatment includes: first, set a 2μm reversible screen for filtration, remove the relevant waste liquid and enter the waste liquid pool, and the rotating nozzle flushes the enriched substances on the filter screen; the flushed liquid enters the digestion column for digestion operation; the digestion column can perform the digestion process, and the digested solution enters the flotation layer; the flotation layer is provided with a solution addition port, and a saturated sodium chloride solution can be added for flotation. After the flotation is completed, the lower layer enters the waste liquid pool, and the supernatant enters the separation layer; the separation layer contains 3 reversible filters with decreasing pore sizes, and the supernatant is filtered by the microporous mesh to complete the separation of microplastics. After the water sample is filtered by the 2μm reversible filter, the microplastics will be intercepted by the filter, and the rotating nozzle can flush the screen up and down, flushing the microplastics into the digestion column. The digestion column can be disassembled, and 30% hydrogen peroxide solution is added to the digestion column as the digestion solution, and it is placed in an oscillating incubator for digestion at 80rpm and 60℃ for 48h. After the digestion is completed, the integrated device is assembled. The flotation layer is used for the flotation of the digestion solution. After the solution enters this layer, add saturated sodium chloride solution in the liquid adding area. The ratio of saturated sodium chloride solution added is 6g sodium chloride for every 20mL solution. After the flotation is left to stand for 24 hours, open the valve to allow the lower layer of liquid to enter the waste liquid tank, and retain the supernatant to enter the subsequent device to complete the flotation process.

[0063] Horizontal migration simulation includes:

[0064] 1. After the pretreatment step, the water sample enters the simulated migration section, where the microplastics in the water sample are gathered on three reversible filters with decreasing apertures, 2mm, 0.5mm and 0.05mm respectively. The discharged water sample enters the waste liquid tank along the pipeline;

[0065] 2. Collection of microplastics of different sizes: The microplastics gathered on the three filters are divided into three different particle sizes: >2mm, 0.5-2mm and <0.5mm. The rotating nozzle on each filter can be used to wash the microplastics enriched on the filter into the horizontal migration simulation pipeline;

[0066] 3. Simulation of the migration of microplastics: Control valves are provided under the three filters. To simulate the migration of microplastics of a specific size, the control valve under the corresponding filter is opened to allow microplastics of a specific size to enter the corresponding migration simulation pipeline together with the water flow. Each migration pipeline is provided with a sampling water inlet every 50 cm in the horizontal direction, and sampling can be carried out at different locations of the same pipeline;

[0067] 4. Characterization of microplastics after simulated migration; obtain water samples from the sampling water inlet and connect them to the filtration device. The filtration device is equipped with a 2μm mixed fiber filter membrane. The water sample is filtered using the mixed fiber filter membrane. After the filter membrane is dried for 12 hours, it is placed in a glass culture dish. The glass culture dish is placed under a stereo microscope for observation at a magnification of 60 times;

[0068] 5. Qualitative characterization of simulated migrating microplastics; use a micro-Raman imaging spectrometer to analyze the microplastics on the filter membrane, detect the polymer type of the microplastics (785nm laser, voltage 3-5mW, dwell time 0.1s, Raman shift 100-3500cm-1), and identify the polymer category of the microplastics;

[0069] 6. Simulate the size and quantity of migrating microplastics: Observe and count the microplastics collected by different filters and simulated migration under a microscope, record the number of microplastics on the filter membrane in different sampling positions, and divide the microplastic particle size into large-size microplastics (>2mm), medium-size microplastics (0.5-2mm) and small-size microplastics (<0.5mm). Use the software Image J to perform statistical analysis on the microplastics on the filter membrane at different positions, and obtain the migration law of microplastics in the horizontal direction.

[0070] Thus, after the water sample enters, a series of pretreatment processes can be completed in the device, and the water body containing microplastics that has completed the pretreatment is separated and collected into microplastics of different particle sizes, and enters the corresponding parallel horizontal migration simulation pipeline to simulate the horizontal migration of microplastics. The present invention can concentrate the pretreatment of microplastic detection in the water body in one device, simplify the pretreatment operation of microplastics, and can simultaneously separate microplastics of different particle sizes and complete the horizontal migration simulation of microplastics of different particle sizes, which is suitable for the study of the horizontal migration law of microplastics in water bodies. Through the present invention, the workload of separating and extracting microplastics in water bodies can be significantly reduced, and experimental data of simulated horizontal migration of microplastics of different particle sizes in water bodies can be obtained, with the advantages of high separation rate, convenient operation, and reusability.

[0071] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A device for separating and simulating the horizontal migration of microplastics of different particle sizes in water, characterized in that: It includes a water inlet, a primary filter layer, a digestion column and a flotation layer which are arranged in sequence from top to bottom, an impurity filter screen is arranged between the primary filter layer and the water inlet, a flip filter screen is arranged in the primary filter layer, a pretreatment rotary nozzle is arranged on the upper side of the primary filter layer, and the pretreatment rotary nozzle is located above the flip filter screen, a first waste liquid cylinder and a first waste liquid cylinder control valve connected thereto are arranged on one side of the bottom of the primary filter layer, and waste liquid flows through the first waste liquid cylinder control valve into the first waste liquid cylinder; a first valve is arranged between the primary filter layer and the digestion column.

2. The device for separating the horizontal migration of microplastics of different particle sizes in simulated water according to claim 1, characterized in that: The digestion column is connected below the primary filtration layer and is used to receive flushing liquid containing microplastics from the primary filtration layer. The digestion column is detachably connected to the primary filtration layer and the flotation layer, and digestion liquid is added to the digestion column.

3. The device for separating the horizontal migration of microplastics of different particle sizes in simulated water according to claim 2, characterized in that: A liquid adding port is provided on one side of the top of the flotation layer, and a second waste liquid tank and a second waste liquid tank control valve connected thereto are provided on one side of the bottom. The waste liquid flows through the second waste liquid tank control valve into the second waste liquid tank, and a second valve is provided inside the flotation layer. Flotation liquid is added from the liquid adding port to float the digestion liquid, and after the liquid is separated, the lower layer of liquid is passed into the second waste liquid tank to obtain a supernatant containing microplastics.

4. The device for separating the horizontal migration of microplastics of different particle sizes in simulated water according to claim 3, characterized in that: The flotation layer is an L-shaped structure, the upper end of the L-shaped structure is arranged vertically and connected to the digestion column, and the lower end of the L-shaped structure is arranged horizontally and is the microplastic collection area of ​​the microplastic collection and separation mechanism; the microplastic collection area at the lower end of the flotation layer is sequentially provided with a first filter screen, a second filter screen, and a third filter screen with decreasing mesh apertures, and the first filter screen, the second filter screen, and the third filter screen are respectively used to collect large-size microplastics, medium-size microplastics and small-size microplastics; a first filter screen control valve is arranged on the pipeline connected to the bottom of the first filter screen, and a first water inlet control valve is arranged on the side of the first filter screen away from the second filter screen; a second filter screen control valve is arranged on the pipeline connected to the bottom of the second filter screen, and a second water inlet control valve is arranged on the side of the second filter screen facing the first filter screen; a third filter screen control valve is arranged on the pipeline connected to the bottom of the third filter screen, and a third water inlet control valve is arranged on the side of the third filter screen facing the second filter screen.

5. The device for separating the horizontal migration of microplastics of different particle sizes in simulated water according to claim 4, characterized in that: The side of the first filter screen facing the second filter screen, the side of the second filter screen facing the third filter screen, and the side of the third filter screen away from the second filter screen are all provided with collection area rotating nozzles, and the collection area rotating nozzles are connected to the second high-pressure liquid replenishment flusher; the lower end of the flotation layer is connected to the third waste liquid tank through a pipeline.

6. The device for separating the horizontal migration of microplastics of different particle sizes in simulated water according to claim 5, characterized in that: A third water outlet control valve is arranged between the pipe connected to the bottom of the first filter screen and the pipe connected to the third waste liquid tank; a second water outlet control valve is arranged between the pipe connected to the bottom of the second filter screen and the pipe connected to the third waste liquid tank; a first water outlet control valve is arranged between the pipe connected to the bottom of the third filter screen and the pipe connected to the third waste liquid tank; a separation zone control valve is arranged between the pipe connected to the third waste liquid tank and the right end of the third filter screen.

7. The device for separating the horizontal migration of microplastics of different particle sizes in simulated water according to claim 6, characterized in that: The pipe connected to the bottom of the first filter, the pipe connected to the bottom of the second filter, and the pipe connected to the bottom of the third filter are all L-shaped structures, whose upper ends are arranged vertically and connected to the flotation layer, and whose lower ends are arranged horizontally and are horizontal migration simulation areas. The horizontal migration simulation area is provided with a number of sampling water inlets and a water inlet control valve located on one side of the water inlet; the sampling water inlet is connected to a suction filtration device, and the suction filtration device is provided with a mixed fiber filter membrane.

8. The device for separating the horizontal migration of microplastics of different particle sizes in simulated water according to claim 1, characterized in that: The pretreatment rotary nozzle is externally connected to a first high-pressure liquid replenishment flusher, and the first high-pressure liquid replenishment flusher is provided with a linkage switch.

9. A method for separating the horizontal migration of microplastics of different particle sizes in simulated water bodies, characterized in that: A device for separating the horizontal migration of microplastics of different particle sizes in simulated water bodies as described in any one of claims 1 to 8 is used, comprising the following steps: Step 1: Add sample and filter initially; collect water sample and add it from the water inlet, large impurities are trapped on the impurity filter and removed, the water sample is filtered through the reversible filter, microplastics are trapped by the filter, close the first valve, open the first waste liquid cylinder control valve, and the remaining liquid enters the first waste liquid cylinder; close the first waste liquid cylinder control valve, use the pretreatment rotary nozzle to flush the reversible screen up and down, open the first valve, and flush the microplastics into the digestion column; Step 2: digestion and flotation of microplastics; after the flushing liquid containing microplastics enters, the digestion column is disassembled from the device, the digestion liquid is added to the digestion column, and the column is placed in an oscillating incubator for digestion. After the digestion is completed, the integrated device is assembled; the second valve is closed to allow the digestion liquid to enter the flotation layer, and a saturated sodium chloride solution is added to the liquid adding port. After the flotation is allowed to stand, the second waste liquid cylinder control valve is opened to allow the lower layer of liquid to enter the second waste liquid cylinder, and the supernatant where the microplastics are gathered is retained; the second waste liquid cylinder control valve is closed, and the second valve is opened to allow the supernatant to enter the microplastic collection area; Step 3: separation and collection of microplastics: Open the first water inlet control valve, the second water inlet control valve, and the third water inlet control valve, and the large-size microplastics, medium-size microplastics, and small-size microplastics are respectively retained on the first filter screen, the second filter screen, and the third filter screen, and the remaining liquid enters the third waste liquid tank along the pipeline; Step 4: Simulate the migration of microplastics; When simulating the horizontal migration of large-sized microplastics, close the first water inlet control valve, the second water inlet control valve and the first filter screen control valve, use the collection area rotary nozzle to flush the first filter screen up and down, open the first filter screen control valve, and allow the liquid carrying large-sized microplastics to enter the horizontal migration simulation area for horizontal migration. Select horizontal sampling outlets at different positions at the same time to sample for qualitative characterization and quantitative statistics of microplastics; When simulating the horizontal migration of medium-sized microplastics, close the second water inlet control valve, the third water inlet control valve and the second filter screen control valve, use the collection area rotary nozzle to flush the second filter screen up and down, open the second filter screen control valve, and allow the liquid carrying medium-sized microplastics to enter the horizontal migration simulation area for horizontal migration. Select horizontal sampling outlets at different positions at the same time to take samples for qualitative characterization and quantitative statistics of microplastics; When simulating the horizontal migration of small-sized microplastics, close the third water inlet control valve, the separation zone control valve and the third filter screen control valve, use the collection zone rotary nozzle to flush the third filter screen up and down, open the third filter screen control valve, and allow the liquid carrying small-sized microplastics to enter the horizontal migration simulation area for horizontal migration. Select horizontal sampling water outlets at different positions at the same time to take samples through the water intake control valve for qualitative characterization and quantitative statistics of microplastics; Step 5. Record and conduct statistical analysis. Obtain water samples from the sampling inlet and connect them to the filtration device. The filtration device is equipped with a mixed fiber filter membrane. The water sample is filtered using the mixed fiber filter membrane. After the filter membrane is dried, it is placed in a glass culture dish. The glass culture dish is placed under a microscope for observation. The number of microplastics on the filter membrane in sampling at different positions is recorded. At the same time, the particle size of microplastics is divided into large-size microplastics, medium-size microplastics and small-size microplastics. Statistical analysis is performed on the microplastics on the filter membrane at different positions to derive the migration pattern of microplastics in the horizontal direction.

10. The method for separating the horizontal migration of microplastics of different particle sizes in simulated water according to claim 9, characterized in that: The digestion solution in the step 2 is 200 mL of 30% hydrogen peroxide solution, which is placed in an oscillating incubator and digested at 80 rpm and 60° C. for 48 hours; the saturated sodium chloride solution is prepared by adding 6 g of sodium chloride to every 20 mL of solution, and the second waste liquid tank control valve is opened after flotation and standing for 24 hours; the mixed fiber filter membrane in the step 5 is 2 μm, and the filter membrane drying time is 12 hours. The software Image J is used to perform statistical analysis on the microplastics on the filter membranes at different positions; the particle size of large-particle microplastics is >2 mm, the particle size of medium-particle microplastics is 0.5-2 mm, and the particle size of small-particle microplastics is <0.5 mm.

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