A device and method for separating horizontal migration of microplastics of different particle sizes in an analog water body

Abstract

The application discloses a device and method for separating and simulating horizontal migration of microplastics with different particle sizes in an analog water body. The device comprises a water inlet, an initial filtration layer, a digestion column and a flotation layer arranged in sequence. An impurity filter screen is arranged between the initial filtration layer and the water inlet. A reversible filter screen is arranged in the initial filtration layer. A pretreatment rotary nozzle is arranged on the upper part of the side of the initial filtration layer. The pretreatment rotary nozzle is located above the reversible filter screen. A first waste liquid cylinder and a first waste liquid cylinder control valve connected to the first waste liquid cylinder are arranged on one side of the bottom of the initial filtration layer. Waste liquid flows into the first waste liquid cylinder through the first waste liquid cylinder control valve. A first valve is arranged between the initial filtration layer and the digestion column. The device can concentrate the pretreatment of microplastic detection in one device, separate microplastics with different particle sizes at the same time, complete horizontal migration simulation of microplastics with different particle sizes, simplify various operations of the pretreatment, reduce the loss and collection error of microplastics, and realize integrated collection and simulation process.

Description

TECHNICAL FIELD

[0001] The present application relates to a device and method for separating and simulating the horizontal migration of microplastics of different particle sizes in a water body, and belongs to the technical field of microplastic separation and collection. BACKGROUND

[0002] Plastic products have good chemical stability, strong plasticity and low cost, and have been widely used in life and production. Plastic garbage accumulated in the environment can be decomposed into small plastic particles under the action of physics, chemistry and biology. Microplastics refer to plastic particles with a particle size of less than 5mm. At present, the abundance of microplastics in the environment has reached an unnegligible level. Due to the characteristics of wide source, small size and easy migration, microplastics exist widely in various water environments, so the potential ecological risk caused by microplastics needs to be paid attention to.

[0003] In order to study the abundance and occurrence of microplastics in water bodies, systematic field investigation is needed, and microplastics in water bodies are detected by collecting water samples. However, the detection and pretreatment of microplastics are relatively complex at present, and need to be filtered, digested and floated. These pretreatments all need to use different devices and equipment, and the operation is relatively cumbersome. Microplastics are easy to be lost or contaminated in the liquid transfer process of different operations. At the same time, the horizontal migration of microplastics in water bodies involves the occurrence in natural water bodies, and the current research is less involved. The simulation of horizontal migration process is worth further study.

[0004] In summary, the device in the prior art cannot separate microplastics of different particle sizes and complete the simulation of the horizontal migration of microplastics of different particle sizes at the same time, and there are problems such as loss and collection error of microplastics, and the operation is cumbersome, which cannot realize the integrated collection and simulation process. SUMMARY

[0005] In order to solve the above problems, the present application provides a device and method for separating and simulating the horizontal migration of microplastics of different particle sizes in a water body. The pretreatment of microplastic detection in the water body is concentrated in one device, which can separate microplastics of different particle sizes at the same time and complete the simulation of the horizontal migration of microplastics of different particle sizes. And it can simplify various operations of pretreatment, reduce the loss and collection error of microplastics, and realize the integrated collection and simulation process.

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

[0007] In an embodiment of the present application, the digestion column is connected below the initial filtration layer for receiving the flushing liquid containing microplastics from the initial filtration layer, the digestion column is detachably connected between the initial filtration layer and the flotation layer, and a digestion liquid is added into the digestion column.

[0008] In an embodiment of the present application, a liquid adding port is arranged on one side of the top of the flotation layer, a second waste liquid cylinder and a second waste liquid cylinder control valve connected thereto are arranged on one side of the bottom of the flotation layer, waste liquid flows into the second waste liquid cylinder through the second waste liquid cylinder control valve, and a second valve is arranged in the flotation layer; the digestion liquid is floated by adding a flotation liquid from the liquid adding port, the lower layer liquid is introduced into the second waste liquid cylinder after liquid separation, and supernatant containing microplastics is obtained.

[0009] In an embodiment of the present application, the flotation layer is in L-shaped structure, the upper end of the L-shaped structure is vertically arranged and connected with the digestion column, the lower end of the L-shaped structure is horizontally arranged and is a 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 sizes, and the first filter screen, the second filter screen and the third filter screen are respectively used for collecting large particle size microplastics, medium particle size microplastics and small particle size microplastics; a pipeline connected below the first filter screen is provided with a first filter screen control valve, one side of the first filter screen away from the second filter screen is provided with a first water inlet control valve; a pipeline connected below the second filter screen is provided with a second filter screen control valve, one side of the second filter screen facing the first filter screen is provided with a second water inlet control valve; a pipeline connected below the third filter screen is provided with a third filter screen control valve, and one side of the third filter screen facing the second filter screen is provided with a third water inlet control valve.

[0010] In an embodiment of the present application, one side of the first filter screen facing the second filter screen, one side of the second filter screen facing the third filter screen, and one side of the third filter screen away from the second filter screen are all provided with a collection area rotary nozzle, and the collection area rotary nozzle is connected with a second high-pressure liquid supplementing flusher; the lower end of the flotation layer is connected with a third waste liquid cylinder through a pipeline.

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

[0012] In one embodiment of the present application, the pipelines connected to the lower sides of the first, second and third filter screens are all L-shaped structures, the upper ends of which are arranged vertically and communicate with the flotation layer, and the lower ends of which are arranged horizontally and are horizontal migration simulation zones, which are provided with a plurality of sample outlet water inlets and water inlet control valves located on one side of the water inlets; the sample outlet water inlets are 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 application, a first high-pressure liquid supplementing flusher is arranged outside the pretreatment rotary spray head, and the first high-pressure liquid supplementing flusher is provided with a linkage switch.

[0014] The second object of the present application is to provide a method for separating and simulating the horizontal migration of microplastics with different particle sizes in a simulated water body, which uses the device for separating and simulating the horizontal migration of microplastics with different particle sizes in a simulated water body.

[0015] Step one: sample addition and preliminary filtration; the water sample is added from the water inlet, and large impurities are removed by being intercepted on the impurity filter screen; after the water sample is filtered through the reversible filter screen, the microplastics are intercepted by the filter screen; the first valve is closed, the first waste liquid tank control valve is opened, and the remaining liquid enters the first waste liquid tank; the first waste liquid tank control valve is closed, the pretreatment rotary spray head is used to wash the reversible screen up and down, the first valve is opened, and the microplastics after washing enter the digestion column;

[0016] Step two: digestion and flotation of microplastics; after the washing liquid containing microplastics enters, the digestion column is detached from the device, digestion liquid is added to the digestion column, and the digestion is carried out in an oscillation incubator; after the digestion is completed, the integrated device is assembled; the second valve is closed, the digestion liquid enters the flotation layer, saturated sodium chloride solution is added to the liquid inlet, the flotation is placed, the second waste liquid tank control valve is opened, the lower liquid enters the second waste liquid tank, and the supernatant in which the microplastics are gathered is reserved; the second waste liquid tank control valve is closed, the second valve is opened, and the supernatant enters the microplastic collection zone.

[0017] Step three, 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 particle size microplastics, the medium particle size microplastics and the small particle size microplastics are respectively intercepted 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 four, horizontal simulation migration of microplastics;

[0019] When simulating the horizontal migration of large particle size microplastics, the first water inlet control valve, the second water inlet control valve and the first filter screen control valve are closed, the first filter screen is flushed up and down using the rotating nozzle of the collection area, the first filter screen control valve is opened, the liquid carrying large particle size microplastics enters the horizontal migration simulation area for horizontal migration, and the horizontal sampling water outlet at the same time in different positions is sampled for microplastic characterization and quantity statistics;

[0020] When simulating the horizontal migration of medium particle size microplastics, the second water inlet control valve, the third water inlet control valve and the second filter screen control valve are closed, the second filter screen is flushed up and down using the rotating nozzle of the collection area, the second filter screen control valve is opened, the liquid carrying medium particle size microplastics enters the horizontal migration simulation area for horizontal migration, and the horizontal sampling water outlet at the same time in different positions is sampled for microplastic characterization and quantity statistics;

[0021] When simulating the horizontal migration of small particle size microplastics, the third water inlet control valve, the separation area control valve and the third filter screen control valve are closed, the third filter screen is flushed up and down using the rotating nozzle of the collection area, the third filter screen control valve is opened, the liquid carrying small particle size microplastics enters the horizontal migration simulation area for horizontal migration, and the horizontal sampling water outlet at the same time in different positions is sampled for microplastic characterization and quantity statistics;

[0022] Step five, record and statistical analysis; the water sample obtained by the sampling water outlet is connected to the filtration device, the filtration device is provided 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, and the glass culture dish is placed under a microscope for observation; the number of microplastics on the filter membrane in different positions is recorded; at the same time, the particle size of the microplastics is divided into large particle size microplastics, medium particle size microplastics and small particle size microplastics; the microplastics on the filter membranes in different positions are statistically analyzed, and the migration rule of the microplastics in the horizontal direction is obtained.

[0023] In one embodiment of the present application, the digestion solution in step two is 200 mL of 30% hydrogen peroxide solution as a digestion solution, which is placed in a shaking incubator for digestion at 80 rpm and 60 DEG C for 48 h; the proportion of the saturated sodium chloride solution is 6 g of sodium chloride per 20 mL of solution, and the second waste solution cylinder control valve is opened after 24 h of flotation and standing; the mixed fiber filter membrane in step five is 2 um, the filter membrane drying time is 12 h, and the software Image J is used for statistical analysis of microplastics on the filter membrane at different positions; the particle size of large particle size microplastics is > 2 mm, the particle size of medium particle size microplastics is 0.5-2 mm, and the particle size of small particle size microplastics is < 0.5 mm.

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

[0025] (1) The present application can directly perform an integrated pretreatment process in the device after obtaining the water sample, and can concentrate digestion, flotation and separation in one device for processing, thereby simplifying the pretreatment operation of microplastics, reducing the loss and collection error of microplastics, realizing integrated collection and simulation process, and simultaneously separating microplastics of different particle sizes and completing 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, the water body containing microplastics after the pretreatment is separated and collected as microplastics of different particle sizes, and enters the corresponding parallel horizontal migration simulation pipeline for horizontal migration simulation of microplastics. The present application can significantly reduce the workload of separating and extracting microplastics in water bodies, and obtain experimental data of simulated horizontal migration of microplastics of different particle sizes in water bodies, and has the advantages of high separation rate, convenient operation, and reusability.

[0026] (2) The present application is convenient for experimental personnel to separate water bodies and obtain experimental data of microplastics of different particle sizes, has high extraction rate, is convenient to operate, and can be reused.

[0027] (3) The present application enriches microplastics on filter screens of different pore sizes after pretreatment of the water sample, completes separation and collection of microplastics, is convenient to operate and can be reused. After separation and collection are completed, horizontal migration simulation of microplastics of different particle sizes can be further performed on this basis, which further provides research for the migration and enrichment of microplastics in water bodies, is convenient to operate, and has high efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced as follows, and the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creating labor on the premise of not creating labor.

[0029] Figure 1 A structural schematic diagram of a device for separating and simulating horizontal migration of microplastics of different particle sizes in a water body is provided in the present application.

[0030] Figure 2 A structural schematic diagram of a filter screen control valve, a sample outlet water inlet, and a water inlet control valve is provided in the present application.

[0031] Figure 3 A flow chart of a method for separating and simulating horizontal migration of microplastics of different particle sizes in a water body is provided in the present application.

[0032] The figure mark explanation: 1, water inlet; 2, primary filter layer; 3, digestion column; 4, flotation layer; 5, impurity filter screen; 6, reversible filter screen; 7, first filter screen; 8, second filter screen; 9, third filter screen; 10, first high-pressure liquid supplementing flusher; 11, pretreatment rotary spray head; 12, second high-pressure liquid supplementing flusher; 13, liquid inlet; 14, first waste liquid cylinder; 15, first waste liquid cylinder control valve; 16, first valve; 17, second valve; 18, sample outlet water inlet; 19, linkage switch; 20, first water inlet control valve; 21, second water inlet control valve; 22, third water inlet control valve; 23, first filter screen control valve; 24, second filter screen control valve; 25, third filter screen 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 cylinder control valve; 31, second waste liquid cylinder; 32, third waste liquid cylinder; 33, collection zone rotary spray head; 34, water inlet control valve. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0034] In the description of the present application, it should be noted that the terms "upper", "lower", "inner", "outer", "top", "bottom", etc. indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", "third" are only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0035] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "linking" should be understood in a broad sense, for example, it can be fixed connection, or detachable connection, or integral connection; it can be mechanical connection, or electrical connection; it can be direct connection, or indirect connection through intermediate medium, or internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0036] As shown in Figures 1-2 The embodiment of the present application provides a device for separating and simulating horizontal migration of microplastics with different particle sizes in a water body. In some embodiments, the device comprises, from top to bottom, a water inlet 1, a primary filtration layer 2, a digestion column 3 and a flotation layer 4. An impurity filter screen 5 is arranged between the primary filtration layer 2 and the water inlet 1. A reversible filter screen 6 is arranged in the primary filtration layer 2. A pretreatment rotary nozzle 11 is arranged on the upper side of the primary filtration layer 2. The pretreatment rotary nozzle 11 is located above the reversible filter screen 6. A first high-pressure liquid supplementing flusher 10 is connected to the pretreatment rotary nozzle 11. The first high-pressure liquid supplementing flusher 10 is provided with a linkage switch 19.

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

[0038] The device for separating and simulating horizontal migration of microplastics with different particle sizes in a water body provided by the embodiment of the present application collects water samples from the water inlet 1. Large impurities are filtered by the impurity filter screen 5. After the water sample is filtered by the reversible filter screen 6, microplastics are intercepted by the reversible filter screen 6, so that the microplastics are enriched on the reversible filter screen 6. 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, the pretreatment rotary nozzle 11 is used to flush the reversible filter screen 6 up and down, the first valve 16 is opened, and the microplastics after flushing enter the digestion column 3.

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

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

[0041] In some embodiments, one side of the top of the flotation layer 4 is provided with a liquid inlet 13, and one side of the bottom is provided with a second waste liquid cylinder 31 and a second waste liquid cylinder control valve 30 connected therewith. The waste liquid flows through the second waste liquid cylinder control valve 30 into the second waste liquid cylinder 31, and the inside of the flotation layer 4 is provided with a second valve 17. The digestion liquid is subjected to flotation by adding a flotation liquid from the liquid inlet 13, and after the liquid separation, the lower layer liquid is introduced into the second waste liquid cylinder 31 to obtain supernatant containing microplastics.

[0042] Specifically, the second valve 17 is closed, the digestion liquid is introduced into the flotation layer 4, the saturated sodium chloride solution is added from the liquid inlet 13, the proportion of the saturated sodium chloride solution is 6 g of sodium chloride per 20 mL of solution, the flotation is statically placed for 24 h, then the second waste liquid cylinder control valve 30 is opened, the lower layer liquid is introduced into the second waste liquid cylinder 31, and the supernatant in which the microplastics are gathered is reserved; the second waste liquid cylinder control valve 30 is closed, and the second valve 17 is opened, so that the supernatant is introduced into the microplastics collection area.

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

[0044] In some embodiments, the microplastic collection area at the lower end of the floatation layer 4 is sequentially provided with a first filter screen 7, a second filter screen 8, and a third filter screen 9 with decreasing mesh aperture, which are respectively used to collect large particle size microplastics, medium particle size microplastics, and small particle size microplastics; a pipeline connected below the first filter screen 7 is provided with a first filter screen control valve 23, and a side of the first filter screen 7 away from the second filter screen 8 is provided with a first water inlet control valve 20; a pipeline connected below the second filter screen 8 is provided with a second filter screen control valve 24, and a side of the second filter screen 8 facing the first filter screen 7 is provided with a second water inlet control valve 21; a pipeline connected below the third filter screen 9 is provided with a third filter screen control valve 25, and a side of the third filter screen 9 facing the second filter screen 8 is provided with a third water inlet control valve 22; a side of the first filter screen 7 facing the second filter screen 8, a side of the second filter screen 8 facing the third filter screen 9, and a side of the third filter screen 9 away from the second filter screen 8 are all provided with a collection area rotating nozzle 33, and the collection area rotating nozzle 33 is connected with a second high-pressure liquid supplementing flusher 12; and the lower end of the floatation layer 4 is connected with a third waste liquid tank 32 through a pipeline.

[0045] The first water inlet control valve 20, the second water inlet control valve 21, and the third water inlet control valve 22 are opened, and the large particle size microplastics, the medium particle size microplastics, and the small particle size microplastics are respectively intercepted 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 aperture of the first filter screen 7 can be 2 mm, the mesh aperture of the second filter screen 8 can be 0.5 mm, and the mesh aperture of the third filter screen 9 can be 0.05 mm. The first high-pressure liquid supplementing flusher 10 and the second high-pressure liquid supplementing flusher 12 can be controlled by a linkage switch 19.

[0046] Further, a third water outlet control valve 28 is arranged between the pipeline connected below the first filter screen 7 and the pipeline connected with the third waste liquid tank 32; a second water outlet control valve 27 is arranged between the pipeline connected below the second filter screen 8 and the pipeline connected with the third waste liquid tank 32; a first water outlet control valve 26 is arranged between the pipeline connected below the third filter screen 9 and the pipeline connected with the third waste liquid tank 32; and a separation area control valve 29 is arranged between the pipeline connected with the third waste liquid tank 32 and the right end of the third filter screen 9.

[0047] In some embodiments, the pipeline connected below the first filter screen 7, the pipeline connected below the second filter screen 8, and the pipeline connected below the third filter screen 9 are all L-shaped structures, the upper ends of which are vertically arranged and in communication with the floatation layer 4, and the lower ends of which are horizontally arranged and are horizontal migration simulation areas, and the horizontal migration simulation areas are provided with a plurality of sampling and water taking ports 18 and water taking port control valves 34 located on one side of the sampling and water taking ports 18.

[0048] When simulating the horizontal migration of large-particle microplastics, the first water inlet control valve 20, the second water inlet control valve 21 and the first filter screen control valve 23 are closed, the first filter screen 7 is flushed up and down by using the collection area rotating nozzle 33, the first filter screen control valve 23 is opened, the liquid carrying large-particle microplastics enters the horizontal migration simulation area for horizontal migration, and the horizontal sampling water outlet 18 at different positions is selected for sampling for microplastic characterization, qualitative and quantitative statistics.

[0049] When simulating the horizontal migration of medium-particle microplastics, the second water inlet control valve 21, the third water inlet control valve 22 and the second filter screen control valve 24 are closed, the second filter screen 8 is flushed up and down by using the collection area rotating nozzle 33, the second filter screen control valve 24 is opened, the liquid carrying medium-particle microplastics enters the horizontal migration simulation area for horizontal migration, and the horizontal sampling water outlet 18 at different positions is selected for sampling for microplastic characterization, qualitative and quantitative statistics.

[0050] When simulating the horizontal migration of small-particle microplastics, the third water inlet control valve 22, the separation area control valve 29 and the third filter screen control valve 25 are closed, the third filter screen 9 is flushed up and down by using the collection area rotating nozzle 33, the third filter screen control valve 25 is opened, the liquid carrying small-particle microplastics enters the horizontal migration simulation area for horizontal migration, and the horizontal sampling water outlet 18 at different positions is selected for sampling for microplastic characterization, qualitative and quantitative statistics.

[0051] When the sampling water outlet 18 collects water samples, the sampling water outlets 18 at different horizontal positions are simultaneously sampled and analyzed, the sampling water outlet 18 is connected to a suction filtration device, the suction filtration device is provided with a mixed fiber filter membrane with a pore size of 2 μm, the water sample is suction filtered by using the mixed fiber filter membrane, after the filter membrane is dried for 12 h, the filter membrane is placed in a glass culture dish, and the glass culture dish is placed under a stereomicroscope for observation at 60 times magnification; the number of microplastics on the filter membrane at different positions is recorded, and the particle size of the microplastics is divided into large-particle microplastics (> 2 mm), medium-particle microplastics (0.5-2 mm) and small-particle microplastics (< 0.5 mm). The software Image J is used to statistically analyze the microplastics on the filter membranes at different positions, and the migration rule of the microplastics in the horizontal direction is obtained.

[0052] In addition, the embodiment of the present application also provides a method for separating and simulating the horizontal migration of microplastics with different particle sizes in a water body, and the method uses the device for separating and simulating the horizontal migration of microplastics with different particle sizes in a water body.

[0053] Step one, sample loading and initial filtration; water sample is collected from the water inlet 1, large impurities are removed by being intercepted on the impurity filter screen 5, and microplastics are intercepted by the filter screen after the water sample is filtered through the reversible filter screen 6, the first valve 16 is closed, the first waste liquid tank control valve 15 is opened, and the remaining liquid enters the first waste liquid tank 14; the first waste liquid tank control valve 15 is closed, the pretreatment rotating nozzle 11 is used to flush the reversible screen 6 up and down, the first valve 16 is opened, and the microplastics are flushed into the digestion column 3 after the flushing;

[0054] Step two, digestion and flotation of microplastics; after the flushing liquid containing microplastics enters, the digestion column 3 is detached from the device, 200 mL of 30% hydrogen peroxide solution is added as a digestion solution in the digestion column 3, and the digestion is carried out in an oscillation incubator at 80 rpm and 60°C for 48 h, and after the digestion is completed, the integrated device is assembled; the second valve 17 is closed, the digestion solution enters the flotation layer 4, the saturated sodium chloride solution is added to the liquid inlet 13, the proportion of the saturated sodium chloride solution is 6 g of sodium chloride per 20 mL of solution, and after the flotation is placed for 24 h, the second waste liquid tank control valve 30 is opened, the lower liquid enters the second waste liquid tank 31, and the supernatant in which the microplastics are gathered is reserved; the second waste liquid tank control valve 30 is closed, and the second valve 17 is opened, so that the supernatant enters the microplastic collection area;

[0055] Step three, separation and collection of microplastics; the first water inlet control valve 20, the second water inlet control valve 21, and the third water inlet control valve 22 are opened, large-diameter microplastics, medium-diameter microplastics, and small-diameter microplastics are intercepted 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 four, horizontal simulation migration of microplastics;

[0057] When the horizontal migration of large-diameter microplastics is simulated, the first water inlet control valve 20, the second water inlet control valve 21, and the first filter screen control valve 23 are closed, the collection area rotating nozzle 33 is used to flush the first filter screen 7 up and down, the first filter screen control valve 23 is opened, the liquid carrying large-diameter microplastics enters the horizontal migration simulation area for horizontal migration, and the same time is selected to take water samples at different positions of the horizontal direction sample outlet 18 for microplastic characterization, qualitative and quantitative statistics;

[0058] When the horizontal migration of medium-diameter microplastics is simulated, the second water inlet control valve 21, the third water inlet control valve 22, and the second filter screen control valve 24 are closed, the collection area rotating nozzle 33 is used to flush the second filter screen 8 up and down, the second filter screen control valve 24 is opened, the liquid carrying medium-diameter microplastics enters the horizontal migration simulation area for horizontal migration, and the same time is selected to take water samples at different positions of the horizontal direction sample outlet 18 for microplastic characterization, qualitative and quantitative statistics;

[0059] When simulating the horizontal migration of small particle size microplastics, the third water inlet control valve 22, the separation zone control valve 29 and the third filter screen control valve 25 are closed, the third filter screen 9 is washed up and down by using the collection zone rotating nozzle 33, the third filter screen control valve 25 is opened, the liquid carrying small particle size microplastics enters the horizontal migration simulation zone for horizontal migration, and the horizontal direction sampling water outlet 18 at different positions is selected to take water samples through the water outlet control valve 34 for microplastic characterization, qualitative analysis and quantity statistics;

[0060] Step five, recording and statistical analysis; the water sample taken by the sampling water outlet 18 is connected to the filtration device, the filtration device is provided with a 2 μm mixed fiber filter membrane, the water sample is filtered by using the mixed fiber filter membrane, after the filter membrane is dried for 12 h, it is placed in a glass culture dish, and the glass culture dish is placed under a stereomicroscope for observation at 60 times magnification; the number of microplastics on the filter membrane in different positions is recorded; at the same time, the particle size of the microplastics is divided into large particle size microplastics, medium particle size microplastics and small particle size microplastics; the microplastics on the filter membrane at different positions are statistically analyzed by using software ImageJ, and the migration rule of the microplastics in the horizontal direction is obtained.

[0061] In summary, the device and method for simulating the horizontal migration of microplastics with different particle sizes in a separation simulation water body are provided, the collected water sample is pretreated first, the horizontal migration of microplastics in the water sample to be measured is simulated after the pretreatment, and the simulation is collected for research and analysis.

[0062] The pretreatment includes: first, a 2 μm reversible screen is set to filter, relevant waste liquid is removed into a waste liquid tank, and a rotating nozzle is used to wash the enriched substances on the filter screen; the washed liquid enters a digestion column for digestion operation; the digestion column can perform a digestion process, and the solution after digestion enters a flotation layer; the flotation layer is provided with a solution adding port, and saturated sodium chloride solution can be added for flotation; after the flotation is completed, the lower liquid enters the waste liquid tank, and the supernatant enters a separation layer; the separation layer includes three reversible filter screens with decreasing hole diameters, and the supernatant is filtered by the microporous screen to complete the separation of microplastics. After the water sample is filtered by the 2 μm reversible filter screen, the microplastics are intercepted by the filter screen, and the rotating nozzle can wash the filter screen up and down to wash the microplastics into the digestion column. The digestion column can be disassembled and treated, 30% hydrogen peroxide solution is added as a digestion liquid in the digestion column, and the digestion is performed in an oscillation incubator at 80 rpm and 60℃ for 48 h. After the digestion is completed, the integrated device is assembled. The flotation layer is used for the flotation of the solution after digestion, saturated sodium chloride solution is added in the liquid adding area after the solution enters the layer, the proportion of the added saturated sodium chloride solution is 6 g of sodium chloride per 20 mL of solution, and after the flotation is statically placed for 24 h, the valve is opened to make the lower liquid enter the waste liquid tank, and the supernatant enters the subsequent device to complete the flotation process.

[0063] The horizontal migration simulation includes:

[0064] 1. After the pretreatment step, the water sample enters the simulated migration part, and the microplastics in the water sample are aggregated on three reversible filters with decreasing pore sizes, 2 mm, 0.5 mm, and 0.05 mm. The discharged water sample enters the waste tank along the pipeline;

[0065] 2. Collection of microplastics of different sizes; the microplastics aggregated on the three filters are divided into three types of different particle sizes: >2 mm, 0.5-2 mm, and <0.5 mm. The rotating spray head on each filter can flush the microplastics enriched on the filter into the horizontal migration simulation pipeline;

[0066] 3. Simulation of microplastic migration; the three filters are provided with control valves. To simulate the migration of microplastics of a specific size, the control valve under the corresponding filter is opened, allowing the microplastics of the specific size to enter the corresponding migration simulation pipeline along with the water flow. Each migration pipeline is provided with a sample outlet every 50 cm in the horizontal direction, allowing sampling at different positions in the same pipeline;

[0067] 4. Characterization of microplastics after simulated migration; the water sample taken from the sample outlet is connected to a filtration device, which is provided with a 2 μm mixed fiber filter. The water sample is filtered using the mixed fiber filter. After the filter is dried for 12 h, it is placed in a glass culture dish, and the glass culture dish is placed under a stereomicroscope for observation at 60 times magnification;

[0068] 5. Qualitative analysis of simulated migration microplastics; the microplastics on the filter are analyzed using a micro-Raman imaging spectrometer to detect the polymer type (785 nm laser, voltage 3-5 mW, residence time 0.1 s, Raman shift 100-3500 cm-1), and identify the polymer category;

[0069] 6. Particle size and quantity statistics of simulated migration microplastics; the microplastics collected by different filters and simulated to migrate are observed and counted under a microscope. The number of microplastics on the filter at different sampling positions is recorded, and the microplastics are divided into large particle size microplastics (>2 mm), medium particle size microplastics (0.5-2 mm), and small particle size microplastics (<0.5 mm). The microplastics on the filter at different positions are statistically analyzed using software Image J to obtain the migration rule of microplastics in the horizontal direction.

[0070] Therefore, the water sample can complete a series of pretreatment processes in the device, the water body containing microplastics after the pretreatment is separated and collected as microplastics of different particle sizes, and the microplastics are subjected to horizontal migration simulation in corresponding parallel horizontal migration simulation pipelines. The application can concentrate the pretreatment of microplastics in water bodies in one device, simplify the pretreatment operation of microplastics, separate microplastics of different particle sizes, and complete the horizontal migration simulation of microplastics of different particle sizes, and is suitable for the research on the horizontal migration law of microplastics in water bodies. The application can significantly reduce the workload of separating and extracting microplastics in water bodies, and obtain experimental data of the simulated horizontal migration of microplastics of different particle sizes in water bodies, and has the advantages of high separation rate, convenient operation, and reusability.

[0071] The above examples are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that the technical solutions recorded in the foregoing examples can be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should 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, The system includes, from top to bottom, an inlet, a primary filtration layer, a digestion column, and a flotation layer. An impurity filter screen is installed between the primary filtration layer and the inlet. A reversible filter screen is installed within the primary filtration layer. A pretreatment rotary nozzle is located on the upper side of the primary filtration layer, above the reversible filter screen. A first waste liquid cylinder and a first waste liquid cylinder control valve are located on one side of the bottom of the primary filtration layer. Waste liquid flows through the first waste liquid cylinder control valve into the first waste liquid cylinder. A first valve is installed between the primary filtration layer and the digestion column. The digestion column is connected to the primary filtration layer... Below the filter layer, a flushing liquid containing microplastics from the primary filter layer is received. The digestion column is detachably connected to the primary filter layer and the flotation layer, and digestion liquid is added to the digestion column. A liquid inlet is provided on one side of the top of the flotation layer, and a second waste liquid cylinder and a second waste liquid cylinder control valve connected to it are provided on one side of the bottom. Waste liquid flows through the second waste liquid cylinder control valve into the second waste liquid cylinder. A second valve is provided inside the flotation layer. Flotation liquid is added through the liquid inlet to float the digestion liquid. After the liquid is separated, the lower layer liquid is passed into the second waste liquid cylinder to obtain a supernatant containing microplastics.

2. The device for separating and simulating the horizontal migration of microplastics of different particle sizes in simulated water, as described in claim 1, is characterized in that... The flotation layer has an L-shaped structure. The upper end of the L-shaped structure is vertically arranged and connected to the digestion column, while the lower end of the L-shaped structure is horizontally arranged and serves as 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 equipped with a first filter screen, a second filter screen, and a third filter screen with decreasing mesh sizes. The first, second, and third filter screens are used to collect large-diameter microplastics, medium-diameter microplastics, and small-diameter microplastics, respectively. A first filter screen control valve is installed on the pipe connected to the lower part of the first filter screen, and a first water inlet control valve is installed on the side of the first filter screen facing away from the second filter screen. A second filter screen control valve is installed on the pipe connected to the lower part of the second filter screen, and a second water inlet control valve is installed on the side of the second filter screen facing the first filter screen. A third filter screen control valve is installed on the pipe connected to the lower part of the third filter screen, and a third water inlet control valve is installed on the side of the third filter screen facing the second filter screen.

3. The device for separating and simulating the horizontal migration of microplastics of different particle sizes in simulated water, as described in claim 2, is characterized in that... A collection zone rotary 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. The collection zone rotary nozzle is connected to a second high-pressure replenishing flusher. The lower end of the flotation layer is connected to a third waste liquid cylinder through a pipe.

4. The device for separating and simulating the horizontal migration of microplastics of different particle sizes in simulated water, as described in claim 3, is characterized in that... A third water outlet control valve is provided between the pipe connected to the lower part of the first filter screen and the pipe connected to the third waste liquid cylinder; a second water outlet control valve is provided between the pipe connected to the lower part of the second filter screen and the pipe connected to the third waste liquid cylinder; a first water outlet control valve is provided between the pipe connected to the lower part of the third filter screen and the pipe connected to the third waste liquid cylinder; and a separation zone control valve is provided between the pipe connected to the third waste liquid cylinder and the right end of the third filter screen.

5. The apparatus for separating and simulating the horizontal migration of microplastics of different particle sizes in simulated water, as described in claim 4, is characterized in that... The pipes connected to the bottom of the first filter screen, the second filter screen, and the third filter screen are all L-shaped structures. Their upper ends are vertically arranged and connected to the flotation layer, and their lower ends are horizontally arranged and form a horizontal migration simulation zone. The horizontal migration simulation zone is provided with several sample outlets and a control valve for the outlets located on one side. The sample outlets are connected to a filtration device, which is equipped with a mixed fiber filter membrane.

6. The apparatus for separating and simulating the horizontal migration of microplastics of different particle sizes in simulated water, as described in claim 1, is characterized in that... The pretreatment rotary nozzle is externally connected to a first high-pressure replenishing flusher, which is equipped with a linkage switch.

7. A method for separating the horizontal migration of microplastics of different particle sizes in simulated water, characterized in that, The apparatus for separating and simulating the horizontal migration of microplastics of different particle sizes in simulated water, as described in claim 5, includes the following steps: Step 1: Sample addition and initial filtration; collect water samples and add them through the inlet. Large impurities are trapped and removed by the impurity filter screen. After the water sample passes through the flip-over filter screen, microplastics are trapped by the filter screen. Close the first valve and open the first waste liquid cylinder control valve. The remaining liquid enters the first waste liquid cylinder. Close the first waste liquid cylinder control valve and use the pretreatment rotary nozzle to rinse the flip-over screen from top to bottom. Open the first valve to rinse away the microplastics and then enter the digestion column. Step 2: Digestion and Flotation of Microplastics; After the flushing solution containing microplastics enters, the digestion column is detached from the device. Digestion solution is added to the digestion column, and it is placed in a shaking incubator for digestion. After digestion, the integrated device is reassembled. The second valve is closed, allowing the digestion solution to enter the flotation layer. Saturated sodium chloride solution is added to the inlet. After flotation and settling, the control valve of the second waste liquid cylinder is opened, allowing the lower layer liquid to enter the second waste liquid cylinder, while retaining the supernatant from which the microplastics have accumulated. The control valve of the second waste liquid cylinder is closed, and the second valve is opened, allowing the supernatant to enter the microplastic collection area. Step 3: Separation and collection of microplastics; Open the first, second, and third inlet control valves. Large-diameter, medium-diameter, and small-diameter microplastics are respectively trapped on the first, second, and third filter screens, while the remaining liquid enters the third waste liquid tank along the pipeline. Step 4: Simulate horizontal migration of microplastics; When simulating the horizontal migration of large-diameter microplastics, the first water inlet control valve, the second water inlet control valve, and the first filter control valve are closed. The first filter is flushed up and down using the rotating nozzle in the collection area. The first filter control valve is then opened to allow the liquid carrying the large-diameter microplastics to enter the horizontal migration simulation area for horizontal migration. Samples are taken from the horizontal sampling ports at different locations at the same time to characterize and count the number 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 control valve. Use the rotating nozzle in the collection area to flush the second filter up and down. Open the second filter control valve to allow the liquid carrying medium-sized microplastics to enter the horizontal migration simulation area for horizontal migration. Select the horizontal sampling outlets at different locations at the same time to perform microplastic characterization and quantity statistics. When simulating the horizontal migration of small-diameter microplastics, the third inlet control valve, the separation zone control valve, and the third filter control valve are closed. The third filter is flushed up and down using the rotating nozzle in the collection zone. The third filter control valve is then opened to allow the liquid carrying the small-diameter microplastics to enter the horizontal migration simulation zone for horizontal migration. Samples are taken from the horizontal sampling ports at different locations at the same time through the sampling port control valve for microplastic characterization, qualitative analysis, and quantity statistics. Step 5: Record and Statistical Analysis; A water sample is taken from the sampling port and connected to a 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 petri dish and observed under a microscope. The number of microplastics on the filter membrane is recorded at different sampling locations. Simultaneously, the microplastic particle size is categorized into large-diameter, medium-diameter, and small-diameter microplastics. Statistical analysis is performed on the microplastics on the filter membrane at different locations to determine the migration pattern of microplastics in the horizontal direction.

8. The method for separating the horizontal migration of microplastics of different particle sizes in simulated water according to claim 7, characterized in that, In step two, the digestion solution is 200 mL of 30% hydrogen peroxide solution, which is placed in a shaking incubator and digested at 80 rpm and 60°C for 48 h. The saturated sodium chloride solution ratio is 6 g of sodium chloride added per 20 mL of solution. After flotation and settling for 24 h, the control valve of the second waste liquid tank is opened. In step five, the mixed fiber filter membrane is 2 μm in diameter and the filter membrane is dried for 12 h. The microplastics on the filter membrane at different locations are statistically analyzed using ImageJ software. The particle size of large-diameter microplastics is >2 mm, the particle size of medium-diameter microplastics is 0.5–2 mm, and the particle size of small-diameter microplastics is <0.5 mm.

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