CN114308401A

CN114308401A - Micro-plastic flotation device and method

Info

Publication number: CN114308401A
Application number: CN202210006651.6A
Authority: CN
Inventors: 张平; 张宇宁; 陈姗
Original assignee: University of Macau
Current assignee: University of Macau
Priority date: 2022-01-05
Filing date: 2022-01-05
Publication date: 2022-04-12
Anticipated expiration: 2042-01-05
Also published as: CN114308401B

Abstract

The invention discloses a micro-plastic flotation device and a micro-plastic flotation method, and belongs to the technical field of micro-plastic pollutant treatment. The device comprises a flotation agent containing container, a separation column, a liquid recovery container, an aerator and a screen; the separation column is used for filling a micro-plastic sample to be floated, a flotation agent inlet is formed in the column wall of the separation column, and the flotation agent containing container is connected with the flotation agent inlet through a pipeline; the liquid recovery container is covered outside the separation column, and the gas output end of the aerator is positioned in the separation column; the upper end of the separation column is provided with a micro plastic overflow port; the screen cloth is located the micro-plastic overflow mouth below in order to collect the micro-plastic solid that flows out by the micro-plastic overflow mouth, and the screen cloth is cyclic annular, and the inner wall suit separation column of screen cloth and with separation column activity sealing contact, the outer wall of screen cloth and the inner wall activity sealing contact of liquid recovery container. The device can conveniently and rapidly separate the micro plastic from the micro plastic sample to be treated by flotation, and has high recovery efficiency. The corresponding method is simple and easy to operate.

Description

Micro-plastic flotation device and method

Technical Field

The invention relates to the technical field of micro-plastic pollutant treatment, in particular to a micro-plastic flotation device and a micro-plastic flotation method.

Background

As an emerging persistent pollutant, Micro Plastics (MPs) are now found in the maja nata and the world peak marumar peak deepest in the world's oceans. As a notable contaminant, Microplastics (MPs) pose potential toxicity and ecological risks to animals and even humans. Worse still, it is estimated that the number of MPs in the natural system may increase continuously due to continued degradation and fragmentation even if the release of all plastics into the environment is stopped immediately. The small size makes detection and toxicology studies of MP challenging. Moreover, plastic particles ingested by these organisms, small enough to occupy the stomach volume, cause satiety, and thus reduce food intake, malnutrition, and even death by the organisms. Furthermore, as size decreases, the total surface area of the MPs increases, and then the absorptive capacity increases, presenting an increased likelihood of intrinsic toxicity. These toxic substances may accumulate in animal tissues through the food chain and food network.

However, this does not mean that the micro-plastic is useless. Researchers have proposed that the age and origin of plastics in the ocean can be traced by analyzing the metallic elements on the surface of MPs. In addition, the use of MP as a pharmaceutical carrier can be used to treat brain diseases. Furthermore, many applications of MPs have been developed to achieve recycling economy, such as: the micro plastic fiber is reused as cellulose powder for dyeing; producing a new plastic product using the recycled and sorted MP as a filler; the recovered MP is regarded as a filler of various materials having low quality control requirements, and the like.

According to the handbook of plastics recycling, most of the recycled waste plastics need to be crushed to less than 5 mm, i.e., to reach the specified micro-plastic size. And the classified MPs are directly recycled, so that the crushing process can be omitted, and the efficiency of plastic recycling and re-granulation is improved.

However, at present, no device or method for conveniently and rapidly recycling micro-plastics continuously exists.

In view of this, the invention is particularly proposed.

Disclosure of Invention

The invention aims to provide a micro-plastic flotation device and a micro-plastic flotation method, which aim to solve the technical problem.

The application can be realized as follows:

in a first aspect, the present application provides a microplastic flotation device comprising a flotation agent holding container, a separation column, a liquid recovery container, an aerator, and a screen;

the separation column is used for filling a matrix-containing micro-plastic sample to be floated, a flotation agent inlet is formed in the column wall of the separation column, and the flotation agent containing container is connected with the flotation agent inlet through a pipeline;

the liquid recovery container is covered outside the separation column, and the gas output end of the aerator is positioned in the separation column;

the upper end of the separation column is provided with a micro plastic overflow port;

the screen cloth is located the micro-plastic overflow mouth below in order to collect the micro-plastic solid that flows out by the micro-plastic overflow mouth, and the screen cloth is cyclic annular, and the inner wall suit separation column of screen cloth and with separation column activity sealing contact, the outer wall of screen cloth and the inner wall activity sealing contact of liquid recovery container.

In an alternative embodiment, the flotation agent holding container comprises a first holding container for holding water, a second holding container for holding a saturated NaCl solution, and a third holding container for holding an oil solution;

the flotation agent inlet is selectively connected to each holding container in one of the following ways according to different flotation stages:

the first method is as follows: only communicates with the first container;

the second method comprises the following steps: only communicating with the second container;

the third method comprises the following steps: and is simultaneously communicated with the second container and the third container.

In an alternative embodiment, when the flotation agent inlet is in communication with both the second holding vessel and the third holding vessel;

the flotation agent access port comprises a first access port communicated with the second container and a second access port communicated with the third container, and the first access port and the second access port are located on the same horizontal plane and are symmetrically arranged by taking the axis of the separation column as a symmetry axis.

In an alternative embodiment, the micro plastic flotation device further comprises a magnetic stirrer and a magnetic stirrer, wherein the magnetic stirrer is arranged at the bottom of the separation column, and the lower end of the separation column is in contact with the magnetic stirrer.

In an alternative embodiment, the microplastic flotation device further comprises a peristaltic pump connected to a conduit between the flotation agent holding container and the flotation agent inlet.

In an alternative embodiment, the micro plastic flotation device further comprises an electric stirrer, and the stirring end of the electric stirrer is positioned at the micro plastic overflow port.

In an alternative embodiment, the micro plastic flotation device further comprises a support and a lifting platform, wherein the support is used for supporting the electric stirrer, and the support and the aerator are arranged on the lifting platform.

In a second aspect, the present application provides a method for micro-plastic flotation, wherein a micro-plastic sample to be floated is subjected to micro-plastic flotation by using the micro-plastic flotation device of any one of the previous embodiments.

In an alternative embodiment, the micro-plastic sample to be floated is a soil containing micro-plastic;

in an alternative embodiment, the micro-plastic comprises at least one of butadiene styrene, polycarbonate, polypropylene, and polystyrene.

In an alternative embodiment, the following phases are included, carried out in succession:

the first stage is as follows: continuously introducing water in the first container into a separation column filled with a micro-plastic sample to be floated and a magnetic stirrer, opening the magnetic stirrer when the liquid level in the separation column is close to a flotation agent inlet, and when the liquid level in the separation column reaches a micro-plastic overflow port, overflowing the micro-plastic separated by water from the micro-plastic overflow port and separating the micro-plastic through a screen;

and a second stage: on the basis of the first stage, turning on an aerator to aerate the separation column;

and a third stage: on the basis of the second stage, saturated NaCl solution is continuously introduced into the separation column instead of water;

a fourth stage: on the basis of the third stage, continuously introducing the oil solution into the separation column;

each stage lasts 3-5 min.

In alternative embodiments, the oil in the oil solution comprises corn oil, peanut oil, olive oil, or sesame oil.

In an alternative embodiment, the oil solution is a corn oil solution.

In alternative embodiments, the corn oil solution has a corn oil to solvent volume ratio of 5:95 to 15: 85; preferably 5: 95.

In an alternative embodiment, the water and saturated NaCl are introduced at a flow rate of 11.55-11.58L/min and the oil is introduced at a flow rate of 0.6-0.62L/min.

In an alternative embodiment, the screen is divided into four zones by cross-bars, the four zones being used in turn to collect the micro-plastic overflowing from the four stages, in the same direction.

The beneficial effect of this application includes:

according to the micro-plastic flotation device and the micro-plastic flotation method, the sample to be treated containing micro-plastic is filled in the separation column, and different types of micro-plastic are decomposed from the matrix according to the mixing of the flotation agent and the sample and the combination of the density and the solubility of the micro-plastic and the matrix of the sample. The method is simple and efficient, can quickly separate various micro-plastics from the matrix, has high flotation recovery rate, and provides an effective means for sustainable recovery and research of the micro-plastics.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.

FIG. 1 is a schematic structural diagram of a micro plastic flotation device provided herein;

FIG. 2 is a graph showing the results of the recovery efficiency of four types of microplastic particles purchased in test example 1 of the present application at each stage in different treatment groups;

FIG. 3 is a graph showing the results of the recovery efficiency of four types of micro plastic particle fragments in the post-consumer plastic product of test example 2 of the present application;

FIG. 4 is a graph showing the results of the floating rate of primary microplastic particles at different concentrations for different oil types in test example 3 of the present application;

FIG. 5 is a graph showing the results of primary microplastic particle flotation in various matrices for various concentrations of corn oil in test example 3 of the present application.

Icon: a-a second container; b-a first peristaltic pump tube; c-a first peristaltic pump; d-a liquid recovery vessel; e-a magnetic stirrer; f-a separation column; g-screen mesh; an H-electric stirrer; i-an aerator; j-lifting platform; k-a second peristaltic pump; l-a second peristaltic pump tube; m-a third container.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

The micro plastic flotation device and method provided by the present application are specifically described below.

As shown in fig. 1, the present application proposes a micro plastic flotation device, which comprises a flotation agent container, a separation column F, a liquid recovery container D, an aerator I and a screen G.

The separation column F is used to pack the matrix-containing micro-plastic sample to be floated. The separation column F may, for example, be cylindrical, although in other embodiments it may have a square, triangular or other cross-sectional shape.

The separating column F is in a long and narrow form, so that on one hand, the separating time of the micro-plastic is prolonged, on the other hand, particles with higher density can fall back for enough time, and the separating accuracy of the micro-plastic is improved.

In some alternative embodiments, the separation column F may have a diameter of 5cm and a height of 40 cm. In other embodiments, the diameter and height of the separation column F may be appropriately adjusted.

The bottom of the separation column F is in a sealed state, and the top is in an open state. Preferably, the upper end of the separation column F is also provided with a micro-plastic overflow port to facilitate the micro-plastic to overflow with the flotation agent.

Furthermore, the column wall of the separation column F is also provided with a flotation agent inlet, and the flotation agent containing containers are connected through the pipeline flotation agent inlet.

Specifically, the container for holding the flotation agent comprises a first container for holding water (ultrapure water), a second container for holding a saturated NaCl solution a and a third container for holding an oil solution M.

The flotation is mainly divided into four stages in combination with the following flotation method, and the flotation agent inlet is selectively connected with each container in one of the following ways according to different flotation stages:

the first method is as follows: only communicated with a first container (water), and the mode corresponds to a first stage and a second stage;

the second method comprises the following steps: only the second container (A) (saturated NaCl solution) is communicated, and the mode corresponds to the third stage;

the third method comprises the following steps: and simultaneously communicated with a second container A (saturated NaCl solution) and a third container M (oil solution), and the mode corresponds to a fourth stage.

Preferably, when the flotation agent inlet is communicated with the second container A and the third container M simultaneously; the flotation agent access port comprises a first access port communicated with the second container A and a second access port communicated with the third container M, and the first access port and the second access port are located on the same horizontal plane and are symmetrically arranged by taking the axis of the separation column F as a symmetry axis.

The flotation agent inlet is connected to each container by a peristaltic pump tube, which can be, for example and without limitation, 16 gauge.

In some embodiments, the peristaltic pump tube used to pump water into the separation column F may be used in common with the peristaltic pump tube used to pump oil solution into the separation column F, while the peristaltic pump tube used to pump saturated NaCl into the separation column F is used separately. For the sake of distinction, the peristaltic pump tube for pumping in water or oil solution is defined below as the first peristaltic pump tube B, and the peristaltic pump tube for pumping in saturated NaCl is the second peristaltic pump tube L. And in the fourth stage, the end of the first peristaltic pump tube B communicated with the first container is switched to be communicated with the second sub-container M.

Correspondingly, the micro-plastic flotation device also comprises a peristaltic pump, and the peristaltic pump is connected with a pipeline between the flotation agent containing container and the flotation agent inlet. That is, the first peristaltic pump tube B and the second peristaltic pump tube L are connected with the first peristaltic pump C and the second peristaltic pump K, respectively, to pump water, a saturated NaCl solution, and an oil solution into the separation column F as required.

The liquid recovery container D covers the separation column F and is mainly used for recovering liquid overflowing from the separation column F.

The screen G is located the micro-plastic overflow mouth below in order to collect the micro-plastic solid that flows out by the micro-plastic overflow mouth, and this screen G is cyclic annular, and the inner wall suit separation column F of screen G and with separation column F activity sealing contact, the outer wall of screen G and the inner wall activity sealing contact of liquid recovery container D. The screens G in this application can be rotated according to different stages in a clockwise or counterclockwise direction.

The aperture of the screen G can be set to 100-1000 μm, and can be specifically adjusted according to the size of the micro-plastic to be separated. The screen G is preferably a transparent screen G for easy observation.

For reference, the screen G can be divided into four zones by cross bars, and the four zones are sequentially used for collecting micro plastic overflowing from the four stages along the same direction.

Taking the screen G as a circle as an example, the screen G is equally divided into four collecting areas by a cross-shaped cross bar, and the four collecting areas sequentially and correspondingly collect the micro-plastics from the first stage to the fourth stage in a clockwise or anticlockwise direction.

It should be noted that the number of the collecting areas separated by the screen G can be adjusted according to the number of the flotation stages in the actual flotation process.

Further, in the present application, the gas output of the aerator I is located within the separation column F. Preferably, the gas output end of the aerator I has an aerator stone suspended at a distance of about 10cm from the bottom of the separation column F.

By arranging the aerator I, the aeration stone can generate a large amount of fine bubbles to be damaged stably, and the gas can be ensured to be uniformly diffused in the column under the control of the surface tension of the outlet liquid, so that the buoyancy is provided for small-sized micro plastic. Because the suspended aeration stone has a certain volume, the vortex generated by the magnetic stirrer E can be cut off, and the vortex is prevented from floating high-density and low-density particles together in the rising process. In addition, the device is beneficial to prolonging the separation time of the micro-plastic under the condition of stable density change, and the potential micro-plastic flotation agent classification capability of the device is improved.

Furthermore, the micro-plastic flotation device also comprises a magnetic stirrer E and a magnetic stirrer, wherein the magnetic stirrer is arranged at the bottom of the separation column F, and the lower end of the separation column F is in contact with the magnetic stirrer. The arrangement of the magnetic stirrer E and the magnetic stirrer is beneficial to fully and uniformly mixing and contacting the sample to be treated with water or a flotation agent.

Further, the micro-plastic flotation device can also comprise an electric stirrer H, and the stirring end of the electric stirrer H is positioned at the micro-plastic overflow port.

The above-mentioned electric stirrer H can act as a scraper to prevent micro-plastic reaching the level of the overflow from adhering to the column wall, thus helping to push micro-plastic into the overflow to speed up the flotation process.

Further, the micro-plastic flotation device also comprises a support and a lifting platform J, wherein the support is used for supporting the electric stirrer H, and the support and the aerator I are arranged on the lifting platform J.

By arranging the lifting platform J, the heights of the aerator I, the electric stirrer H and the like can be adjusted as required, and the applicability of the device is improved.

Correspondingly, the application also provides a micro-plastic flotation method, and the micro-plastic flotation device is adopted to perform micro-plastic flotation on the micro-plastic sample to be floated.

The sample of the micro-plastic to be floated may, by reference, be soil containing the micro-plastic, although the matrix may be other substances. The micro plastic includes at least one of butadiene styrene, polycarbonate, polypropylene, and polystyrene.

It should be noted that the apparatus and method provided herein are particularly useful for micro-plastic flotation and separation of the type described above.

In some embodiments, the microplastic flotation process provided herein includes the following stages performed in series:

the first stage is as follows: continuously introducing water in the first container into a separation column F filled with a micro-plastic sample to be floated and a magnetic stirrer, opening a magnetic stirrer E when the liquid level in the separation column F is close to a flotation agent inlet (which can be understood as a first inlet, and the position of the first inlet can be about 5cm from the bottom of the column for example), and when the liquid level in the separation column F reaches a micro-plastic overflow port, overflowing the micro-plastic separated by water from the micro-plastic overflow port and separating the micro-plastic through a screen G;

and a second stage: on the basis of the first stage, the aerator I is turned on to aerate the separation column F;

and a third stage: on the basis of the second stage, the saturated NaCl solution is continuously introduced into the separation column F instead of water (i.e. in this stage, no water is introduced, and the flotation agent is only saturated NaCl solution);

a fourth stage: on the basis of the third stage, continuously introducing the oil solution into a separation column F;

each stage can last for 3-5min (preferably 3 min), and after each stage is finished, the screen G is rotated by 90 degrees.

It can be understood that: in the first stage, water is introduced into a separation column F; in the second stage, ultrapure water is introduced into the separation column F, and the aerator I is started to generate air in the separation column F; the third stage is to introduce saturated NaCl solution into the separation column F while maintaining the aerator I on to generate air in the separation column F; the fourth stage is to introduce the oil solution and the saturated NaCl solution into the separation column F at the same time, and to maintain the aerator I turned on to generate air in the separation column F.

In alternative embodiments, the oil in the oil solution may comprise, for example, corn oil, peanut oil, olive oil, or sesame oil.

Preferably, the oil solution is a corn oil solution. Preferably, the volume ratio of the corn oil to the solvent (e.g., water) in the corn oil solution is 5:95 to 15: 85. Most preferably, the corn oil to solvent ratio in the corn oil solution is 5:95 by volume. With the proportion, the flotation efficiency can be optimal. If the amount of the oil is too large, the emulsification reaction may be severe.

In the present application, the flow rates for both water and saturated NaCl may be set at 11.55-11.58L/min (corresponding to a peristaltic pump parameter of about 200rpm), and the flow rate for oil may be set at 0.6-0.62L/min (corresponding to a peristaltic pump parameter of about 7 rpm).

The rotation speed of the magnetic stirrer E may be 1000rpm, and the rotation speed of the electric stirrer H may be 100 rpm.

Bearing on, the principle of the micro plastic flotation device that this application provided includes: different types of microplastics are separated from a substrate (e.g., soil) by differences in density and solubility. Specifically, a sample to be treated containing the micro-plastic is filled in the separation column F, different flotation agents are introduced according to different stages and are mixed with the sample, so that pollutants are separated from other components in the sample, and the micro-plastic has lower density than soil and oleophilic property, can continuously float upwards under the condition that the flotation agents are continuously introduced (continuous flow condition), and overflows from an overflow port to achieve the separation purpose. The method is simple and efficient, can quickly separate various micro-plastics from the matrix, and provides an effective means for sustainable recovery and research of the micro-plastics.

Test example 1

Adopt the micro-plastic flotation device that this application provided, all experiments all use deionized water earlier, in the experimentation, through the recovery efficiency of four kinds of micro-plastics of four stage tests.

The test set up a control (no soil) group (corresponding to a in fig. 2) and three soil treatment groups (each group is different in soil), each group of the control group and the soil treatment group contains micro plastic particles which are plastic products with the diameter of below 4 mm, and the content of each micro plastic particle in each group is equal. The plastic product is plastic raw material particles (primary plastic pellet) sold by a plastic factory, belongs to primary micro plastic (primary micro plastic), and is specifically purchased in Taobao: dongguan integrity plastic raw material. The substrates of the three soil treatment groups were loam, sandy sediments and muddy sediments (corresponding to b, c and d in fig. 2 in sequence), respectively, and the micro plastic particles were butadiene styrene (ABS), Polycarbonate (PC), polypropylene (PP) and Polystyrene (PS). The micro-plastic flotation device is tested for the recovery efficiency of the micro-plastic.

The test method is as follows:

the first stage is as follows: continuously introducing ultrapure water into a separation column F (the diameter is 5cm multiplied by the height is 40 cm); when the liquid level in the separation column F is about 5cm from the top of the separation column F, turning on the magnetic stirrer E (1000rpm) and the electric stirrer H (100 rpm); separating for 3min, and collecting the micro plastic overflowing from the overflow port in the first collecting region of the screen G.

And a second stage: rotating the screen G by 90 degrees clockwise to enable the second collecting area to correspond to the overflow port, and starting the aerator I (namely introducing ultrapure water and air into the separation column F at the same time, wherein an aeration stone of the aerator I is suspended at a position which is about 10cm away from the bottom of the separation column F) on the basis of the first stage; separating for 3min, and collecting the micro plastic overflowing from the overflow port in the second collecting region of the screen G.

And a third stage: rotating the screen G by 90 degrees clockwise to enable the third collecting area to correspond to the overflow port, cutting off the introduction of pure water on the basis of the second stage, and introducing saturated NaCl solution into the separation column F instead (namely introducing the saturated NaCl solution and air into the separation column F at the same time); separating for 3min, and collecting the micro plastic overflowing from the overflow port in the third collecting region of the screen G.

A fourth stage: rotating the screen G by 90 degrees clockwise to enable the fourth collecting area to correspond to the overflow port, and introducing a 5 vt% corn oil aqueous solution into the separation column F on the basis of the third stage (namely simultaneously introducing the corn oil aqueous solution, a saturated NaCl solution and air into the separation column F); separating for 3min, and collecting the micro plastic overflowing from the overflow port in the fourth collecting region of the screen G.

In the above process, the parameters of the peristaltic pump for introducing water or saturated NaCl solution were about 200rpm, and the parameters of the peristaltic pump for introducing oil were 7 rpm.

The results are shown in FIG. 2, where a is the control group and b, c and d correspond to three soil groups in sequence (similar to FIG. 3).

As can be seen from the figure: PP is the first micro-plastic recovered, and the recovery efficiency of the PP in the first stage can reach 82.5-95%, which is slightly lower than 100% of the control group. However, in some cases, PS and PC are also found in the first stage. In the second stage, four kinds of micro-plastics are collected no matter how the soil matrix is, and the recovery efficiency of PS is the highest and accounts for 75-82.5%. However, in the control group, only two kinds of microplastics were collected. In the third stage, PC becomes the main micro-plastic overflowing from the saturated NaCl extraction liquid, and the recovery rate reaches 50-67.5%. PP and PS were recovered in the first three stages. The ABS is recovered from the second stage to the fourth stage, and the recovery efficiency of each stage is similar. The recovery efficiency of ABS in the fourth stage is 15-35%.

Test example 2

The present test example differs from test example 1 in that: the plastic products contained in the control group and the soil treatment group were pieces (post-consumer plastic fragments) of the plastic product of test example 1 found in daily life, and were classified as secondary microplastic.

The results of the measurement using the same test method as in test example 1 are shown in FIG. 3, and it can be seen from FIG. 3 that: the total recovery rates of ABS, PC, PP and PS are 93.34%, 89.99%, 96.66% and 93.33% in the control group respectively, and the total recovery rate of ABS in the three soil treatment groups is 76.67% -93.33%; the total recovery rate of PC is 86.66-93.34%; the overall recovery of PP is 89.99-100% and the overall recovery of PS is 86.66-93.33%. In the first three phases of the three soil matrices, PP and PS were almost completely recovered, except for the fourth phase of the sandy sediment, which recovered 3.33% PS. In the last three phases of the three soil matrices, the vast majority of both PC and ABS are recovered. In the fourth stage of the control and treatment groups, the recovery efficiency of PC and ABS ranged from 3.33% to 30%.

Test example 3

The floating experiment is taken as a preliminary experiment of the oil extraction experiment, and the whole process only needs to be observed in a conical flask. To determine the kind of oil most suitable for MP extraction, the total flotation efficiency at 1000rpm for 10min of 4 primary micro plastic particles (butadiene styrene ABS, polycarbonate PC, polypropylene PP and polystyrene PS) was tested with 0%, 2% and 5% oil/NaCl solution ratio as extraction solution with 4 oils (corn oil, peanut oil peanout oil, olive oil and sesame oil, respectively (as described in fig. 4).

The results of this figure show that: the average flotation efficiency of each oil-treated group was higher than that of the control (oil-free) group. The average flotation efficiency of the corn oil group in 2 vt% and 5 vt% oil/NaCl solutions was 100% and 99%, respectively, higher or equal to the other 3 oil groups.

Therefore, corn oil is more suitable than other oils for testing the recovery efficiency of MP in the final plant experiment.

Further, FIG. 5 shows the extraction efficiency of different MP types in 2 vt% and 5 vt% corn oil/NaCl ratio solutions. In the treatment groups of 3 soils (a is loam, b is sandy sediment and c is silt), the treatment effects of the corn oil/NaCl solutions at 2 vt% and 5 vt% are not significantly different in most cases, but the flotation efficiency of the treatment groups MPs is significantly reduced when the ratio of the corn oil/NaCl solution in the sandy sediment is 2 vt%.

Therefore, 5% corn oil/NaCl was better suited for testing MP recovery efficiency in the final plant experiment.

To sum up, the device and the method provided by the application can conveniently and rapidly separate micro-plastics, especially butadiene styrene (ABS), Polycarbonate (PC), polypropylene (PP) and Polystyrene (PS), from micro-plastic samples to be processed by flotation, and have the advantages of high recovery efficiency, simple operation and easily controlled conditions.

The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes will occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A micro-plastic flotation device is characterized by comprising a flotation agent containing container, a separation column, a liquid recovery container, an aerator and a screen;

the screen is located the micro-plastic overflow mouth below is in order to collect by the micro-plastic solid that flows out of micro-plastic overflow mouth, the screen is cyclic annular, the inner wall suit of screen the separation column and with the separation column activity sealing contact, the outer wall of screen with the inner wall activity sealing contact of liquid recovery container.

2. A microplastic flotation device according to claim 1, wherein the flotation agent holding containers comprise a first holding container for holding water, a second holding container for holding a saturated NaCl solution, and a third holding container for holding an oil solution;

the flotation agent inlet is selectively connected with each container according to different flotation stages in one of the following ways:

the first method is as follows: communicating only with the first holding container;

the second method comprises the following steps: only communicating with the second holding container;

3. A microplastic flotation device according to claim 2, wherein when the flotation agent inlet is in simultaneous communication with the second holding vessel and the third holding vessel;

the flotation agent access port comprises a first access port communicated with the second container and a second access port communicated with the third container, and the first access port and the second access port are located on the same horizontal plane and symmetrically arranged by taking the axis of the separation column as a symmetry axis.

4. The microplastic flotation device of any one of claims 1 to 3, further comprising a magnetic stirrer and a magnetic stirrer, wherein the magnetic stirrer is placed at the bottom of the separation column, and the lower end of the separation column is in contact with the magnetic stirrer.

5. The microplastic flotation device of claim 1, further comprising a peristaltic pump connected to a conduit between the flotation agent holding container and the flotation agent inlet.

6. The microplastic flotation device of claim 1, further comprising an electric agitator having an agitation end located at the microplastic overflow;

preferably, the micro plastic flotation device further comprises a support and a lifting platform, wherein the support is used for supporting the electric stirrer, and the support and the aerator are both arranged on the lifting platform.

7. A method for the flotation of microplastics, characterized in that a microplastics sample to be floated is subjected to microplastics flotation by using the microplastics flotation apparatus according to any one of claims 1-6;

preferably, the micro-plastic sample to be floated is soil containing micro-plastic;

preferably, the micro plastic comprises at least one of butadiene styrene, polycarbonate, polypropylene and polystyrene.

8. A microplastic flotation process according to claim 7, comprising the following stages performed in succession:

each stage lasts 3-5 min.

9. The micro-plastic flotation process of claim 8, wherein the oil in the oil solution comprises corn oil, peanut oil, olive oil, or sesame oil;

preferably, the oil solution is a corn oil solution;

preferably, the volume ratio of the corn oil to the solvent in the corn oil solution is 5:95-15: 85; even more preferably 5: 95;

preferably, the flow rates of water and saturated NaCl are 11.55-11.58L/min and the flow rate of oil is 0.6-0.62L/min.

10. A microplastic flotation process according to claim 8, wherein the screen is divided into four zones by cross bars, the four zones being successively used to collect the microplastic overflowing from the four stages in the same direction.