An apparatus and method for the separation and enrichment of particulate microplastics based on electrophoresis.

Abstract

This invention discloses an electrophoresis-based device and method for separating and enriching particulate microplastics. The device includes an electrophoresis separation chamber with a first inert electrode inside; a second inert electrode positioned below the first inert electrode for filtering the input water sample containing the microplastics to be separated, and a pressure difference between the first and second inert electrodes to enrich the filtered microplastic solution; the first and second inert electrodes are connected to a power source via wires; a filtrate chamber for storing pure water is positioned directly below the second inert electrode; a filtrate outlet structure is positioned below the filtrate chamber; a valve for discharging the enriched microplastic solution is positioned on the outer layer of the electrophoresis separation chamber above the second inert electrode; and an inlet structure for introducing the water sample containing the microplastics to be separated is positioned at the top of the electrophoresis separation chamber. This invention features a simple structure, no complex operating devices, easy-to-replace components, and low cost.

Description

Technical Field

[0001] This invention belongs to the field of water treatment technology and relates to a device and method for separating and enriching particulate microplastics based on electrophoresis. Background Technology

[0002] Currently, plastics are widely used in many aspects of daily life and industrial production. The increasing demand for plastic products has led to a rapid increase in plastic production, from 1.5 million tons in the 1950s to 368 million tons in 2019, and is projected to reach 12 billion tons by 2050. Microplastics generally refer to plastic fragments with a diameter of less than 5 millimeters, and can be divided into primary and secondary sources. Primary microplastics mainly come from products used in daily life and industrial production, such as the microbeads in toothpaste and facial cleanser, as well as plastic particles generated by the friction between car tires and road surfaces. Secondary microplastics are tiny plastic particles formed from the decomposition of large pieces of plastic waste in the environment through physical, chemical, and biological processes. Microplastics have been detected in soil, groundwater, and marine environments, and have even been found in polar ice caps, the Mariana Trench, and uninhabited islands. Microplastics can enter the body through the digestive tract, respiratory tract, and skin contact. Once inside the body and distributed to various tissues and organs, they can cause various toxic effects, endangering biosafety and human health. Therefore, it is essential to enrich and separate microplastics in water bodies.

[0003] The main methods for enriching and separating microplastics include membrane filtration and electrocoagulation. Membrane filtration is widely used in the advanced treatment of drinking water, utilizing the selective permeability of membranes with different pore sizes to retain microplastics. While widely applied, it also suffers from problems such as pore blockage and membrane abrasion. Electrocoagulation, under the influence of an electric field, uses a sacrificial anode metal electrode to generate metal cationic flocculants, which combine with suspended particles in the water to form flocs, thus retaining suspended solid particles. It is often used in industrial wastewater treatment. However, the high energy consumption increases the operating cost of electrocoagulation. Furthermore, prolonged electrolysis can lead to electrode fouling, requiring optimization to reduce power consumption and electrode fouling. Due to the problems of material wear and tear, long operating times, and high costs associated with these methods, there is an urgent need to develop a method and apparatus for enriching and separating microplastics that can operate quickly and efficiently at a low cost. Summary of the Invention

[0004] To solve the above problems, the technical solution adopted by the present invention is: a device for separating and enriching particulate microplastics based on electrophoresis, characterized in that: it includes...

[0005] Electrophoretic separation chamber;

[0006] The electrophoretic separation chamber is equipped with a first inert electrode;

[0007] A second inert electrode is disposed below the first inert electrode for filtering the input water sample containing microplastics to be separated, and a pressure difference is formed between the first inert electrode and the second inert electrode to enrich the filtered microplastic solution.

[0008] The first inert electrode and the second inert electrode are respectively connected to the power supply via wires;

[0009] A filtrate chamber for storing pure water is provided directly below the second inert electrode;

[0010] A filtrate outlet structure is provided below the filtrate chamber;

[0011] A valve is provided on the outer layer of the electrophoretic separation chamber above the second inert electrode to discharge the enriched microplastic solution;

[0012] An inlet structure for introducing the microplastic water sample to be separated is provided at the top of the electrophoresis separation chamber.

[0013] Furthermore: the first inert electrode is a graphite electrode or a stainless steel mesh electrode, and the second inert electrode is a stainless steel mesh electrode.

[0014] Furthermore, the dimensions of the second inert electrode are the same as the cross-section of the chamber.

[0015] Furthermore, the device was tested with polystyrene microplastic water samples with a diameter of 1-8 μm.

[0016] Furthermore, the stainless steel mesh has an average pore size of 45μm, a film diameter of 200mm, and a thickness of 0.07mm.

[0017] The method for separating and enriching particulate microplastics based on electrophoresis according to any one of the described methods includes the following steps:

[0018] S1. Add deionized water to the filtrate chamber. The deionized water flows into the filtrate chamber through the stainless steel mesh membrane. When the level of the deionized water in the filtrate chamber is the same as the height of the second inert electrode, stop adding deionized water.

[0019] S2. Inject the water sample containing the microplastics to be separated into the electrophoresis separation chamber;

[0020] S3. Connect the first inert electrode and the second inert electrode to the positive and negative terminals of the power supply, respectively. Apply a DC electric field between the first inert electrode and the second inert electrode. Under the action of electrophoresis, the microplastics in the aqueous sample solution to be separated move towards the first inert electrode and accumulate on the surface of the first inert electrode, thereby achieving the enrichment of microplastics.

[0021] S4. After the energizing time is fixed, use the filtrate outlet structure to export the solution from the bottom of the electrophoretic separation chamber where microplastics have been removed.

[0022] S5. Stop the power supply and discharge the microplastic enrichment solution through the valve;

[0023] S6. Using the inlet structure, deionized water is added to the electrophoretic separation chamber, the second inert electrode is switched to the positive electrode and the first inert electrode is switched to the negative electrode, realizing the reversal of the electric field. The microplastics attached to the first inert electrode enter the liquid under the action of electrophoresis, and then are discharged from the reaction device through the residual liquid discharge valve, thus cleaning the electrode.

[0024] When a DC electric field is applied between the first inert electrode and the second inert electrode, that is, when the height of the microplastic water sample to be separated between the first inert electrode and the second inert electrode is such that the injected microplastic water sample to be separated submerges the first inert electrode.

[0025] The fixed time is determined by the appearance of stratification in the microplastic water sample to be separated.

[0026] The present invention provides an apparatus and method for separating and enriching particulate microplastics based on electrophoresis, which has the following advantages:

[0027] 1. This invention uses a stainless steel mesh membrane as a filter membrane and combines it with electrophoresis technology to achieve the separation of particulate microplastics in water, with a separation efficiency of over 99%;

[0028] 2. In this invention, the filtrate is discharged after the microplastics are separated, avoiding re-mixing of the separated sample solution with the microplastics, which helps to improve the separation effect;

[0029] 3. This invention applies a reverse electric field to cause microplastics to detach from the graphite electrode, preventing the graphite electrode from being adhered to by microplastics and other impurities, which would reduce the current carrying efficiency. It eliminates the need for an additional backwashing device, extending the service life of the graphite electrode and simplifying the device.

[0030] 4. After the filtrate is discharged after separation, the present invention can collect the remaining microplastics for subsequent processing and reuse.

[0031] 5. This invention has a simple structure, no complicated operating devices, and easy-to-replace accessories, resulting in low cost. Appropriate dimensions can be designed according to the site environment to achieve optimal performance.

[0032] Based on the above reasons, the present invention can quickly and efficiently achieve the separation and enrichment of particulate microplastics. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a schematic diagram of a device for enriching and separating particulate microplastics based on electrophoresis;

[0035] Figure 2 This is a front view of a device for enriching and separating particulate microplastics based on electrophoresis;

[0036] Figure 3 A side view (AA) of an electrophoresis-based device for enriching and separating particulate microplastics;

[0037] Figure 4 This is a top view (BB) of a device for enriching and separating particulate microplastics based on electrophoresis;

[0038] Figure 5 This is a process flow diagram for the enrichment and separation of particulate microplastics based on electrophoresis.

[0039] Reference numerals: 1. Positive electrode wire; 2. Electrophoresis separation chamber; 3. Negative electrode wire; 4. Filtration chamber; 5. Filtration output conduit; 6. Sample input conduit; 7. Residual liquid discharge valve; 8. Filtration output valve; 9. Graphite electrode; 10. Stainless steel mesh electrode. Detailed Implementation

[0040] It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0041] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] Figure 1 This is a schematic diagram of a device for enriching and separating particulate microplastics based on electrophoresis;

[0043] Figure 2 This is a front view of a device for enriching and separating particulate microplastics based on electrophoresis;

[0044] Figure 3 A side view (AA) of an electrophoresis-based device for enriching and separating particulate microplastics;

[0045] Figure 4 This is a top view (BB) of a device for enriching and separating particulate microplastics based on electrophoresis;

[0046] An electrophoresis-based device for separating and enriching particulate microplastics includes: an electrophoresis separation chamber 2, a first inert electrode 9, a second inert electrode 10, a filtrate chamber 4, a filtrate outlet structure 5, a valve 8, and a sample introduction structure 6.

[0047] Electrophoretic separation chamber 2; the electrophoretic separation chamber can be cylindrical or cuboid; the shell material of the electrophoretic separation chamber 2 is quartz glass;

[0048] The electrophoretic separation chamber 2 is equipped with a first inert electrode 9;

[0049] A second inert electrode 10 is disposed below the first inert electrode 9 for filtering the input microplastic water sample to be separated, and a pressure difference is formed between the first inert electrode 9 and the second inert electrode 10 to enrich the filtered microplastic solution.

[0050] The first inert electrode 9 is connected to a DC power supply via a positive electrode line 1; the DC power supply (containing a transformer) is used to adjust the voltage.

[0051] The second inert electrode 10 is connected to the negative terminal of the power supply via the negative electrode wire 3;

[0052] A filtrate chamber 4 for storing pure water is provided directly below the second inert electrode;

[0053] A filtrate outlet structure 5 is provided below the filtrate chamber; the filtrate outlet structure includes a filtrate outlet conduit 5, and a filtrate outlet valve 8 is provided on the filtrate outlet conduit 5.

[0054] A valve 7 is provided on the outer layer of the electrophoretic separation chamber above the second inert electrode 10 to discharge the enriched microplastic solution;

[0055] An inlet structure 6 for introducing the microplastic water sample to be separated is provided at the top of the electrophoresis separation chamber. The inlet structure 6 uses an external pump to control the flow rate.

[0056] The first inert electrode is a graphite electrode or a stainless steel mesh electrode, and the second inert electrode is a stainless steel mesh electrode.

[0057] The distance between the first inert electrode 9 and the second inert electrode 10 is more than 20 mm;

[0058] The stainless steel mesh membrane is a three-dimensional network structured metallic material. The stainless steel mesh membrane has an average pore size of 45 μm, a film diameter of 200 mm, and a thickness of 0.07 mm. As a metallic material with a three-dimensional network structure, the stainless steel mesh membrane excludes microplastics larger than its own pore size during the separation process. After adding the water sample to be treated into the separation chamber, on the one hand, microplastics larger than the pore size of the stainless steel mesh membrane are retained; on the other hand, an electric field is formed between the graphite electrode and the stainless steel mesh membrane due to the application of direct current, generating an electrophoretic effect, thereby further improving the separation efficiency. Under the action of electrophoresis, the microplastics in the sample migrate towards the graphite electrode and accumulate near the graphite electrode, thus achieving microplastic enrichment. The enriched filtrate is discharged through the filtrate output conduit 8, obtaining a liquid free of microplastics. The current is stopped, and the microplastic-enriched liquid is discharged through the residual liquid output conduit 5. By adding an appropriate amount of deionized water and reversing the power supply, the microplastics attached to the graphite electrode are detached and enter the solution, and then discharged through the residual liquid discharge valve 7, achieving the cleaning of the graphite electrode.

[0059] The electrophoretic separation chamber is made of quartz glass and is fixed to the tabletop by an iron frame.

[0060] The dimensions of the second inert electrode are the same as the cross-section of the chamber;

[0061] The device was tested with polystyrene microplastic water samples with a diameter of 1-8 μm.

[0062] Example 1: An electrophoresis-based device for separating and enriching particulate microplastics, comprising: an electrophoresis separation chamber 2, a first inert electrode 9, a second inert electrode 10, a filtrate chamber 4, a filtrate outlet structure 5, a valve 8, and a sample introduction structure 6;

[0063] Electrophoretic separation chamber 2; the electrophoretic separation chamber can be cylindrical or cuboid;

[0064] The electrophoretic separation chamber 2 is equipped with a first inert electrode 9;

[0065] A second inert electrode 10 is disposed below the first inert electrode 9 for filtering the input microplastic water sample to be separated, and a pressure difference is formed between the first inert electrode 9 and the second inert electrode 10 to enrich the filtered microplastic solution.

[0066] The first inert electrode 9 is connected to a DC power supply via a positive electrode line 1;

[0067] The second inert electrode 10 is connected to the negative terminal of the power supply via the negative electrode wire 3;

[0068] A filtrate chamber 4 for storing pure water is provided directly below the second inert electrode;

[0069] A filtrate outlet structure 5 is provided below the filtrate chamber; the filtrate outlet structure includes a filtrate outlet conduit 5, and a filtrate outlet valve 8 is provided on the filtrate outlet conduit 5.

[0070] A valve 7 is provided on the outer layer of the electrophoretic separation chamber above the second inert electrode 10 to discharge the enriched microplastic solution;

[0071] An inlet structure 6 for introducing the microplastic water sample to be separated is provided at the top of the electrophoresis separation chamber;

[0072] The electrophoretic separation chamber 2 and the filtrate chamber 4 are an integral structure;

[0073] Example 2: An electrophoresis-based device for separating and enriching particulate microplastics, comprising: an electrophoresis separation chamber 2, a first inert electrode 9, a second inert electrode 10, a filtrate chamber 4, a filtrate outlet structure 5, a valve 8, and a sample introduction structure 6;

[0074] Electrophoretic separation chamber 2; the electrophoretic separation chamber can be cylindrical or cuboid;

[0075] The electrophoretic separation chamber 2 is equipped with a first inert electrode 9;

[0076] A second inert electrode 10 is disposed below the first inert electrode 9 for filtering the input microplastic water sample to be separated, and a pressure difference is formed between the first inert electrode 9 and the second inert electrode 10 to enrich the filtered microplastic solution.

[0077] The first inert electrode 9 is connected to a DC power supply via a positive electrode line 1;

[0078] The second inert electrode 10 is connected to the negative terminal of the power supply via the negative electrode wire 3;

[0079] A filtrate chamber 4 for storing pure water is provided directly below the second inert electrode;

[0080] A filtrate outlet structure 5 is provided below the filtrate chamber; the filtrate outlet structure includes a filtrate outlet conduit 5, and a filtrate outlet valve 8 is provided on the filtrate outlet conduit 5.

[0081] A valve 7 is provided on the outer layer of the electrophoretic separation chamber above the second inert electrode 10 to discharge the enriched microplastic solution;

[0082] An inlet structure 6 for introducing the microplastic water sample to be separated is provided at the top of the electrophoresis separation chamber;

[0083] The electrophoretic separation chamber 2 and the filtrate chamber 4 are separated by a second inert electrode 10; the cross-sectional shape of the electrophoretic separation chamber 2 is the same as the cross-sectional shape of the upper part of the filtrate chamber 4;

[0084] The filtrate chamber 4 is funnel-shaped;

[0085] The size of the second inert electrode is larger than the cross-sectional shape of the electrophoretic separation chamber 2;

[0086] The second inert electrode is fixed by a flange.

[0087] Figure 5 This is a process flow diagram for the enrichment and separation of particulate microplastics based on electrophoresis.

[0088] A method for separating and enriching particulate microplastics based on electrophoresis includes the following steps:

[0089] S1. Add deionized water to the filtrate chamber 4. The deionized water flows into the filtrate chamber 4 through the stainless steel mesh. When the height of the deionized water in the filtrate chamber 4 is the same as the height of the stainless steel mesh, stop adding deionized water.

[0090] S2. Inject the microplastic water sample to be separated into electrophoresis separation chamber 1;

[0091] S3. Connect the first inert electrode 9 and the second inert electrode 10 to the positive and negative terminals of the power supply, respectively. Apply a DC electric field between the first inert electrode 9 and the second inert electrode 10. Under the action of electrophoresis, the microplastics in the aqueous sample solution to be separated move towards the first inert electrode 9 and accumulate on the surface of the first inert electrode, thereby achieving the enrichment of microplastics.

[0092] S4. After the power is applied for a fixed time, the solution in the lower part of the electrophoretic separation chamber 1 with the microplastics removed is exported using the filtrate export structure. The fixed time is confirmed by the appearance of visible stratification in the water sample to be separated for microplastics (based on the concentration and volume of the wastewater being treated).

[0093] S5. Stop the power supply and discharge the microplastic enrichment solution through valve 7;

[0094] S6. Using the inlet structure, deionized water is added to the electrophoresis separation chamber 1, the second inert electrode 10 is connected to the positive electrode, and the first inert electrode 9 is connected to the negative electrode to achieve electric field reversal. The microplastics attached to the first inert electrode 9 enter the liquid under the action of electrophoresis, and then are discharged from the reaction device through the filtrate discharge valve 8 to achieve electrode cleaning.

[0095] When a DC electric field is applied between the first inert electrode and the second inert electrode, that is, when the height of the microplastic water sample to be separated between the first inert electrode and the second inert electrode is such that the injected microplastic water sample to be separated submerges the first inert electrode.

[0096] The determination of the energizing time shows that the separation efficiency of particulate microplastics in a 100mL polystyrene microplastic water sample with a concentration of 1-80mg / L and a diameter of 1-8μm can reach more than 80% within 3 minutes, and the separation efficiency reaches more than 99% after 10 minutes. It can be effectively used for the treatment of wastewater containing microplastics.

[0097] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A device for separating and enriching particulate microplastics based on electrophoresis, characterized in that: include Electrophoretic separation chamber; The electrophoretic separation chamber is equipped with a first inert electrode; A second inert electrode is disposed below the first inert electrode for filtering the input water sample containing microplastics to be separated, and a pressure difference is formed between the first inert electrode and the second inert electrode to enrich the filtered microplastic solution. The first inert electrode and the second inert electrode are respectively connected to the power supply via wires; A filtrate chamber for storing pure water is provided directly below the second inert electrode; A filtrate outlet structure is provided below the filtrate chamber; A valve is provided on the outer layer of the electrophoretic separation chamber above the second inert electrode to discharge the enriched microplastic solution; An inlet structure for introducing the microplastic water sample to be separated is provided at the top of the electrophoresis separation chamber; The first inert electrode is a graphite electrode or a stainless steel mesh electrode, and the second inert electrode is a stainless steel mesh electrode. The device was tested on polystyrene microplastic water samples with a diameter of 1-8 μm.

2. The electrophoresis-based particulate microplastic separation and enrichment device according to claim 1, characterized in that: The second inert electrode has the same dimensions as the cross-section of the chamber.

3. The electrophoresis-based particulate microplastic separation and enrichment device according to claim 1, characterized in that: The stainless steel mesh has an average pore size of 45 μm, a film diameter of 200 mm, and a thickness of 0.07 mm.

4. A method for the separation and enrichment of particulate microplastics based on electrophoresis according to any one of claims 1-3, characterized in that: Includes the following steps: S1. Add deionized water to the filtrate chamber. The deionized water flows into the filtrate chamber through the stainless steel mesh membrane. When the level of the deionized water in the filtrate chamber is the same as the height of the second inert electrode, stop adding deionized water. S2. Inject the water sample containing the microplastics to be separated into the electrophoresis separation chamber; S3. Connect the first inert electrode and the second inert electrode to the positive and negative terminals of the power supply, respectively. Apply a DC electric field between the first inert electrode and the second inert electrode. Under the action of electrophoresis, the microplastics in the aqueous sample solution to be separated move towards the first inert electrode and accumulate on the surface of the first inert electrode, thereby achieving the enrichment of microplastics. S4. After the energizing time is fixed, use the filtrate outlet structure to export the solution from the bottom of the electrophoretic separation chamber where microplastics have been removed. S5. Stop the power supply and discharge the microplastic enrichment solution through the valve; S6. Using the inlet structure, deionized water is added to the electrophoretic separation chamber, the second inert electrode is switched to the positive electrode and the first inert electrode is switched to the negative electrode, realizing the reversal of the electric field. The microplastics attached to the first inert electrode enter the liquid under the action of electrophoresis, and then are discharged from the reaction device through the residual liquid discharge valve, thus cleaning the electrode.

5. A method for the separation and enrichment of particulate microplastics based on electrophoresis according to any one of claims 4, characterized in that: When a DC electric field is applied between the first inert electrode and the second inert electrode, that is, when the height of the microplastic water sample to be separated between the first inert electrode and the second inert electrode is such that the injected microplastic water sample to be separated submerges the first inert electrode.

6. A method for the separation and enrichment of particulate microplastics based on electrophoresis according to any one of claims 4, characterized in that: The fixed time is determined by the appearance of stratification in the microplastic water sample to be separated.

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