Filters and water treatment devices for removing microscale or nanoscale plastic particles from water

Abstract

The present invention relates to a filter (1) for removing micro- or nano-scale plastic particles (6) from water, the filter (1) comprising a filter medium (3; 3a) through which water can flow. Advantageously, the filter medium (3; 3a) comprises spheres (4, 5, 14-17; 4a, 5a, 14a-17a), the spheres (4, 5, 14-17; 4a, 5a, 14a-17a) comprising a layer (7) adapted to receive the plastic particles (6), the spheres (4, 5, 14-17; 4a, 5a, 14a-17a) being in a bidisperse sphere packing arrangement. The bidisperse sphere packing arrangement of the coated layer advantageously allows a very high packing density to be achieved and allows a very high flow through the filter to be set up.

Description

[Technical Field]

[0001] The present invention relates to a filter for removing microscale or nanoscale plastic particles from water, having a filter medium through which water can flow. Furthermore, the present invention relates to an apparatus for water treatment, in particular for removing microscale or nanoscale plastic particles from water.

[0002] Nanoscale plastic particles have a particle size between 1 nm and 100 nm, while microscale plastic particles have a particle size between over 100 nm and less than 35 μm. Such nanoscale or microscale plastic particles, particularly polyethylene (PE), polypropylene (PP), or polyethylene terephthalate (PET), can be ingested by living organisms through drinking water and accumulate in the body, especially in internal organs, as well as in the blood and brain, potentially causing serious health damage. For example, they may cause inflammation of the walls of the human aorta (e.g., https: / / journals.plos.org / plosone / article?id=10.1371 / journal.pone.0260181, last accessed April 19, 2023), or stretching and rupture of cell membranes (e.g., https: / / www.pnas.org / doi / 10.1073 / pnas.2104610118, last accessed April 19, 2023).

[0003] It is well known that water filters are used to treat drinking water, particularly tap water, to remove lime and ions. Furthermore, activated carbon filters are known for purifying water contaminated with bacteria.

[0004] Another filter is known from Chinese Patent Application Publication No. 108926880, U.S. Patent Application Publication No. 2006 / 0260997, and U.S. Patent No. 6,361,710.

[0005] From German Patent Application Publication No. 102020132439, a filter is known that comprises a filter medium having a hydrophobic layer for adsorbing microscale or nanoscale plastic particles. Furthermore, from this publication, a pressurized water treatment apparatus is known. A drawback of nanoscale or microscale plastic particles is that high pressure is required or long processing times must be tolerated to achieve the desired filtering performance.

[0006] The problem that this invention is based on is to provide a filter, as described at the beginning, that can overcome the shortcomings of conventional filters.

[0007] According to the present invention, this problem is solved by the filter medium having a layer configured to receive plastic material particles, wherein the spheres form a bidisperse sphere-filled arrangement.

[0008] The term "reception" refers to both absorption and adsorption, absorption or adsorption, and especially adsorption, i.e., adhesion in a layer that covers at least partially, and especially completely, the surface of a sphere.

[0009] A sphere in the sense of this invention is an object that may deviate from a perfect sphere within the limits of technical manufacturing tolerances. For example, an ellipsoid is considered a sphere in the sense of this invention as long as the difference between its minimum and maximum radii does not exceed 4%.

[0010] Didispersion sphere packing is a sphere packing in which spheres of a first size are mixed with spheres of a second size. The size of the spheres can be determined in particular by their diameter. Didispersion sphere packing in the sense of the present invention has only spheres of the first size and spheres of the second size, taking into account manufacturing tolerances. In didispersion sphere packing in the sense of the present invention, unlike bimodal distribution, there are no spheres of sizes between the first and second sizes, taking into account manufacturing tolerances. It is considered a disadvantage that spheres of such intermediate sizes may occupy intermediate spaces within the filter, potentially significantly reducing the flow through the filter. This could lead to a significant decrease in the possible processing capacity, i.e., the flow performance.

[0011] In one example of didispersion sphere packing, for instance, spheres with a diameter of 3 mm and spheres with a diameter of 1 mm are mixed together. The advantage of didispersion sphere packing is that it allows for a particularly high packing density, where the intermediate spaces between relatively large spheres can be occupied by relatively small spheres, and at the same time, a particularly large specific surface area is achieved, on which plastic particles removed from the water to be treated can adhere. Didispersion sphere packing can advantageously result in a filter with optimal filtering performance.

[0012] In a didispersion sphere-filled system, a first-size sphere is configured to remove a first type of plastic particles from water, while a second-size sphere is provided to remove a second type of plastic particles. This is achieved, in particular, by different coating materials. For example, the first-size sphere can be configured to remove polypropylene (PP), and the second-size sphere can be configured to remove polymethyl methacrylate (PMMA).

[0013] Furthermore, it is also possible that the spheres are arranged in a polydisperse sphere packing configuration. In a tridisperse sphere packing configuration, three spheres of different sizes would be necessary, and in a tetradisperse sphere packing configuration, four spheres of mutually different sizes would be necessary.

[0014] Furthermore, the problem underlying the present invention is to provide a water treatment device that is operable in the building's water pipe network, for example at the faucet in the kitchen of a house. The normal water pressure in the building is between 2 bar and 6 bar, and this water pressure is sufficient to remove plastic particles. At the same time, in the building's water pipe network, there is a need to provide a water treatment device that is operable with a volume flow rate between 5 l / min and 15 l / min, which is common in such water pipe networks.

[0015] This problem is solved by the water treatment device according to the present invention.

[0016] The inventor has recognized that by appropriately selecting the sphere parameters of the spheres arranged to form a binary dispersion sphere packing, particularly the diameter of the spheres or the volume ratio of the spheres in the filter medium, the filter characteristics can be adjusted to meet the purpose. In particular, a very high packing density can be achieved, and the flow rate through the filter can be increased.

[0017] More advantageously, it is possible to ensure that a very high filter performance is achieved, that is, a very large number of plastic particles are removed. This is realized particularly because the specific surface area of the filter medium is particularly large, that is, the surface area of all the coated spheres arranged to form a binary dispersion sphere packing is particularly large, and it is utilized to receive the plastic particles removed from the water.

[0018] The spheres may be hollow spheres or solid spheres.

[0019] Preferably, the sphere packing density is between 55 vol% and 90 vol%, particularly between 65 vol% and 80 vol%, and especially preferably between 71 vol% and 76 vol%. The term vol% refers to the total volume of the filter medium. For example, a percentage of 90 vol% means that 90% of the volume of the filter medium is occupied by spheres, and 10 vol% is available as space for the water to be treated to flow. The above volume percentages result in a very high flow velocity in the filter, as well as a low pressure loss between the inlet and outlet.

[0020] In one embodiment of the present invention, the ratio K of the first diameter d2 of the sphere to the second diameter d1 of the sphere is d The ratio K is between 0.10 and 0.35, preferably between 0.20 and 0.31, and particularly preferably between 0.3. d is defined as the quotient of the diameter d2 of the second type of sphere and the diameter d1 of the first type of sphere, where d1 > d2. Given K d And in the defined first diameter d1, d1 is K d By multiplying by this, the second diameter d2 can be determined. K d It is understood that this is not always 1, because if it were not, a didispersion sphere packing would not exist.

[0021] The inventors of this invention have found that the ratio K d We recognized that when the value is less than 0.10, the flow rate that can pass through the filter according to the present invention is below the flow rate value at which the filter can still be used, for example, under non-pressurized conditions.

[0022] Ratio K greater than 0.35 d Therefore, while the flow rate through the filter certainly increases, the filter performance decreases. This is because the total spherical surface area is no longer sufficient to accommodate the microscale or nanoscale plastic particles that need to be removed from the water.

[0023] The inventor of this invention is K dIt has been found that a ratio of = 0.3 results in a very high-performance filter with high flow rates and high purification capabilities.

[0024] In another embodiment of the present invention, the diameter d1 of the spheres is greater than the diameter d2 of the spheres and is between 0.95 mm and 1.05 mm, preferably between 0.98 mm and 1.02 mm, particularly preferably 1.0 mm. The diameter of the first type of spheres arranged to form a binary sphere filling has been found to be particularly advantageous in order to achieve a sufficiently large specific surface area of the filter medium that can adsorb almost all plastic particles from the water to be purified.

[0025] In one embodiment of the present invention, the ratio K of the volume fraction p2 of the spheres in the total sphere volume in the filter medium to the volume fraction p1 of the spheres in the total sphere volume in the filter medium P is from 0.4 to 0.9, preferably from 0.45 to 0.70, particularly preferably from 0.49 to 0.61. The ratio K P is defined as the quotient of the volume fraction p2 of the second type of spheres (having diameter d2) and the volume fraction p1 of the first type of spheres (having diameter d1), where p1 + p2 = 1. The volume fractions represent the proportion of spheres having diameter d1 and the proportion of spheres having diameter d2, based on the total sphere volume in the filter medium. For example, a ratio K p of 0.5 means that the volume fraction p1 of the spheres having diameter d1 is twice as large as the volume fraction p2 of the spheres having diameter d2. This means that two-thirds of the total sphere volume in the filter medium is classified as spheres having diameter d1. The inventor has found that within the above range, a filter can be provided that can be manufactured particularly economically.

[0026] Preferably, the filter medium has a length between 3 cm and 12 cm, preferably between 4 cm and 10 cm, and particularly preferably between 8 cm and 9 cm, in the direction of flow through the filter. Experiments and flow simulations have shown that filter mediums having such lengths exhibit particularly good purification performance. When the filter medium has a length of 9 cm, it was possible to remove almost all plastic particles having a size between 1 nm and 10 μm from the water. On the other hand, with a length of 8 cm, it was possible to remove almost all plastic particles having a size between 10 μm and 30 μm from the water. The purification performance can be adjusted to suit the purpose by changing the length of the filter medium. Advantageously, the filter according to the present invention can be used in a multifaceted way.

[0027] In another embodiment of the present invention, the volumetric flow rate at which water can flow through the filter is between 4 l / min and 15 l / min, preferably between 7 l / min and 12 l / min. Advantageously, it can be used in daily life without additional pressurization. In particular, it can be used in daily life at home for additional drinking water purification.

[0028] In other embodiments of the present invention, the spheres contain a material having an activatable surface, preferably silicon dioxide. Besides silicon dioxide (SiO2), technical ceramics, particularly zirconium dioxide (ZrO2) or aluminum oxide (Al2O3), may be used. However, the spheres are preferably made of SiO2. Surface activation forms material-dependent silanol groups and / or hydroxide groups, which bond very strongly to the coating material. Advantageously, it is ensured that the coating material, especially coating materials formed from plastics, does not peel off. Surface activation is performed, for example, by a so-called piranha solution (peroxosulfuric acid; 3 parts concentrated sulfuric acid to 1 part 30% hydrogen peroxide solution), or by plasma, for example, so-called plasma etching.

[0029] Preferably, the layer is formed from a hydrophobic or hydrophilic material, particularly from a hydrophobic or hydrophilic material selected from the group consisting of trichlorosilane, cellulose, polyamide, and polyethylene glycol, or the layer has an electric dipole moment and is formed from a material selected from the group consisting of polytetrahydrofuran, polymethyl methacrylate, and zeolite.

[0030] The trichlorosilane is preferably octadecyltrichlorosilane. Layers containing trichlorosilane, particularly octadecyltrichlorosilane (OTS), are hydrophobic and suitable for receiving nanoscale or microscale plastic particles. Layers containing cellulose, polyamide, and / or polyethylene glycol (PEG) are hydrophilic. Hydrogen bonds can be formed between the layer and the plastic particles to absorb them. Hydrophilic layers can remove polyurethane (PU), polycarbonate (PC), polyamide (PA), polyvinyl chloride (PVC), phenolic resins, polymethyl methacrylate (PMMA), and polypropylene (PP) from drinking water.

[0031] The layer may also be formed from a material having a permanent electric dipole moment, preferably tetrahydrofuran and / or natural zeolite. Furthermore, the layer may also be formed from carbon molecular sieve. The zeolite may be natural or synthetic. When the layer has a material with a permanent electric dipole moment, polyurethane (PU), polycarbonate (PC), and polyamide (PA) can be removed from drinking water particularly effectively.

[0032] In one embodiment of the present invention, the layer is formed from a material having permanent dipoles and is configured to induce dipoles in nonpolar plastic particles, preferably acetone and / or polymethyl methacrylate (PMMA). When the layer has a material with permanent dipoles, polymethyl methacrylate (PMMA), polyamide (PA), and polypropylene (PP) can be removed particularly well from drinking water.

[0033] Preferably, the layer has a π-conjugated system and preferably includes a material selected from the group consisting of activated carbon, graphene, organic zeolite, and polycyclic aromatic hydrocarbons. The polycyclic aromatic hydrocarbon is particularly selected from the group consisting of naphthalene, anthracene, benzopyrene, acenaphthene, acenaphthene, fluorene, phenanthrene, fluoranthene, pyrene, benzanthracene, coronene, ovalene, tetracene, pentacene, chrysene, perylene, benzo[a]fluoranthene, benzo[j]fluoranthene, pentafene, hexacene, heptafene, heptacene, trinaphthene, and superphenalene. The use of mesitylene and xylene is also possible.

[0034] The layer having a π-conjugated system can, in particular, remove polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), or polystyrene (PS) from water.

[0035] In one embodiment of the present invention, the layer is formed from a hydrophobic or hydrophilic material selected from the group consisting of cellulose, polyamide, and polyethylene glycol, or the layer is formed from a material having an electric dipole moment and is selected from the group consisting of polytetrahydrofuran, polymethyl methacrylate, and zeolite, and / or the layer includes a material having a π-conjugated system.

[0036] The inventors recognized that while a hydrophobic layer containing trichlorosilane is indeed suitable for receiving nanoscale or microscale plastic particles, better reception of nanoscale or microscale plastic particles can be achieved by a coating other than the aforementioned coating. Advantageously, when a coating material other than the trichlorosilane-containing coating material is used, a filter with 3% to 10% higher filtering performance can be obtained.

[0037] In one embodiment of the present invention, the filter medium has multiple regions, which are arranged sequentially in the direction of flow through the filter, and each region is configured to remove specific plastic particles from water. Advantageously, a single filter can be used collectively to remove various plastic particles from drinking water. This is particularly important for filters intended for household use.

[0038] Adjacent regions are formed identically in terms of sphere size, i.e., with respect to the didispersive sphere packing, and therefore have the same hydrodynamic properties, and the spheres in each region are distinguished from one another only by coating. Furthermore, it is conceivable that each region has different hydrodynamic properties from one another. For example, the first region may contain a didispersive sphere packing with a lower packing density than the adjacent second region. Also, the diameter d of the spheres in the first region 1,1 and d 2,1 d is the diameter of the sphere in the adjacent second region. 1,2 and d 2,2 It may be different from that. The same thing applies to the spherical volume ratio p 1,1 , p 1,2 and p 2,1 , p 2,2 Ratio K p , and the diameter of the sphere d 1,1 d 1,2 and d 2,1 d 2,2 Ratio K d This is also a possibility.

[0039] For example, the first region may be provided for removing polyethylene (PE) particles, and the second region may be provided for removing polymethyl methacrylate (PMMA) particles.

[0040] Furthermore, each region may have two different types of spheres, and these spheres may differ not only in size but also in coating material. For example, a first type of sphere packed with didispersible spheres may be configured to remove a first type of plastic particle, while a second type of sphere packed with didispersible spheres in each region may be configured to remove a second type of plastic particle. Advantageously, the filter and water treatment apparatus according to the present invention can be tailored to specific applications.

[0041] Preferably, the filter material is formed in a rotationally symmetric, preferably cylindrical, shape, and is flowable in the axial direction. Boundary layer effects that degrade filter performance are advantageously minimized or prevented.

[0042] In another embodiment of the present invention, spheres in adjacent regions have different layers from each other. Each region's sphere is covered by a layer having didispersible sphere filling and configured to accept a specific type of plastic particle. For example, a sphere in a first region may have a layer containing a coating material having an electric dipole moment, while a sphere in a second region may have a layer containing a hydrophobic material, and a sphere in a third region may have a layer containing a hydrophilic material. Advantageously, this results in a generally usable filter with high filtering performance. Preferably, a device for water treatment, in particular a device for removing microscale or nanoscale plastic particles from water, has a filter according to any one of claims 1 to 12.

[0043] In one embodiment of the water treatment apparatus according to the present invention, the water treatment apparatus is operable by hydrostatic pressure or the pipe pressure of the building's water pipes. Operable by hydrostatic pressure means that, in a water column located above the filter, the water from which the plastic particles are to be purified can flow through the filter medium based on gravity.

[0044] The inventors have provided a filter that, by having a filter medium containing didispersed spheres of coated spheres, can remove nanoscale or microscale plastic particles from drinking water almost completely without requiring high pressure, despite their small size. The water treatment apparatus according to the present invention is advantageously operable by the pipe pressure of a building's water pipes. A filter cartridge equipped with the filter according to the present invention can be installed, for example, in a kitchen faucet and can be used to treat tap water.

[0045] The present invention will be described in more detail below based on examples and the accompanying drawings that refer to those examples. [Brief explanation of the drawing]

[0046] [Figure 1] This figure shows a water treatment apparatus according to the present invention, which includes multiple embodiments of the filter according to the present invention. [Figure 2] This figure shows the details of the filter according to the present invention. [Modes for carrying out the invention]

[0047] In Figure 1a, the filter 1 of the water treatment apparatus 2, schematically shown in a longitudinal cross-sectional view, includes a cylindrical filter medium 3. The water treatment apparatus 2 is designed to be assembled to a faucet, which is not shown in Figure 1. The filter medium 3 is formed from SiO2 spheres 4 and 5, which are shown in detail in Figure 1c. These SiO2 spheres 4 and 5 are arranged in a didisperse sphere-filled configuration and are covered by a layer 7 that receives plastic particles 6. For clarity, only some of the spheres 4 and 5 of the filter medium 3 are shown in Figure 1a, and not all of them are labeled with reference numerals. Sphere 4 has a diameter d1, while sphere 5 has a diameter d2.

[0048] Water can flow into the filter 1 through an inlet pipe 9 that extends coaxially with the cylindrical axis 8, and after passing through the filter medium, it can flow out of the filter 1 through an outlet pipe 10 that extends coaxially with the cylindrical axis. The filter medium 3 has a length of 9 cm in the direction of flow.

[0049] In Figure 1b, the filter 1, schematically illustrated in a longitudinal cross-sectional view, differs from the filter shown in Figure 1a in that the filter medium 3 has three regions 11, 12, and 13, and in each region, coated SiO2 spheres 4, 5, 14, 15, 16, and 17 are arranged in a didispersed sphere-filling configuration. Here, spheres 4 and 5 have layers containing a different material than the layers of spheres 14 and 15, and spheres 14 and 15 also have layers containing a different material than the layers coating spheres 16 and 17. All regions 11, 12, and 13 are housed in a single filter housing without reference numerals. The filter 1 according to Figure 1b advantageously enables the removal of different types of microscale or nanoscale plastic particles.

[0050] In the embodiment shown in Figure 1b, SiO2 spheres 4 and 5 in region 11 are covered with a layer containing polyamide, while SiO2 spheres 14 and 15 in region 12 are covered with a layer containing polyethylene glycol (PEG). SiO2 spheres 16 and 17 in region 13 are covered with a layer containing polymethyl methacrylate (PMMA). A water treatment apparatus 2 equipped with a filter 1 is provided, which is particularly suitable for removing polyurethane (PU), polypropylene (PP), and polymethyl methacrylate (PMMA) from drinking water.

[0051] Region 13 may also have SiO2 spheres coated with activated carbon. In this embodiment, spheres 4, 14, and 16 are the same size, and spheres 5, 15, and 17 are the same size, but this is not essential.

[0052] Furthermore, spheres 4 and 5 in region 11 have two diameters d 11,1 and d 11,2 It has two diameters d 11,1 and d 11,2 However, the diameter d of spheres 14 and 15 in region 12 12,1 and d 12,2 Unlike their diameter d 12,1 and d 12,2 Also, the diameters d of spheres 16 and 17 in region 13 13,1 and d 13,2 It is also possible that this is not the case.

[0053] Furthermore, it is possible that the SiO2 spheres 4 and 5 in region 11 are covered by different layers. The same applies to the SiO2 spheres 14 and 15 in region 12 and the SiO2 spheres in region 13. 16 17 can also be considered. For clarity, only some of the spheres 4, 5, and 14-17 of the filter medium 3 are shown in regions 11-13.

[0054] To manufacture the filter 1 equipped with the filter medium 3 shown in Figure 1b, regions 11 to 13 are sequentially filled into the housing of the filter 1, which are not numbered in Figure 1, along with a corresponding mixture of didispersing spheres.

[0055] For example, known filter materials, particularly activated carbon, can be used, but they are especially configured in a spherical shape, and it is understood that another region can be provided that exists as a didispersed sphere packing.

[0056] Next, refer to Figure 2. In Figure 2, parts that function identically or similarly are given the same reference numerals as in Figure 1, but each corresponding reference numeral is accompanied by the letter 'a'.

[0057] Table 1 exemplifies the relationship between didispersive sphere packing and three suitable filter media 31, 32, and 33 having their flow characteristics, and the sphere parameters. Details of filter media 32 and 33 are illustrated in Figures 2a and 2b.

[0058] [Table 1]

[0059] The sphere parameters mean the following: d1: Diameter of relatively large spheres (4, 14, 16 in Figure 1) d2: Diameter of relatively small spheres (5, 15, 17 in Figure 1) p1: Volume proportion of relatively large spheres in the total sphere volume p2: Volume proportion of relatively small spheres in the total sphere volume K d : The ratio of d2 to d1 K p : Ratio of p2 to p1 Packing density: The volume ratio of spheres to the total volume of the filter medium. Specific surface area: Total surface area of ​​spheres 4, 5, 14-17 in the filter medium. Volumetric flow: The volumetric flow that passes through the filter medium during water treatment.

[0060] In Figure 2a, a portion of the filter medium 3a shown in the perspective view is formed according to configuration 2 in Table 1, i.e., the filter medium 32.

[0061] In Figure 2b, a portion of the filter medium 3a shown in the perspective view is formed according to configuration 3 in Table 1, i.e., filter medium 33.

[0062] In Figures 2a and 2b, the hatched areas represent cross-sections of some of the individual spheres shown, and some of these cross-sections do not pass through the center of each sphere. This results in a poor visual impression, and accordingly, a different type of sphere packing exists that differs from the didispersed sphere packing.

[0063] Table 2 lists three particularly suitable filter media having didispersion sphere packing. 1’ , 3 2’ and 3 3’ This is illustrated with an example.

[0064] [Table 2]

[0065] Configuration 3 1’ For example, when the length of the filter medium, i.e., the size in the flow direction, was 8.0 cm, a filter efficiency of over 99.0% was achieved. That is, over 99.0% of plastic particles (in this case, polyethylene) with a size between 250 nm and 10 μm were removed from the water flowing through the filter with this filter medium. Here, a flow velocity of 0.02 m / s was achieved at a volumetric flow rate of 6.5 l / min. The filter medium is formed in a cylindrical shape with a diameter of 9 cm.

[0066] The following exemplifies various possibilities for coating SiO2 spheres:

[0067] Example 1: To produce a filter medium from spheres arranged in a didispersion sphere packing configuration, SiO2 spheres with a diameter of 1.00 mm and SiO2 spheres with a diameter of 0.30 mm are placed in a so-called piranha solution (3 parts concentrated sulfuric acid to 1 part 30 wt% hydrogen peroxide solution) for 60 minutes, then rinsed with distilled water, followed by rinsing with acetone and ethanol. Drying is carried out at 130°C for 60 minutes. To coat the spheres with a layer containing polyethylene glycol (PEG), the dried spheres are placed in a solution prepared by mixing 0.9 g of triethylamine (TEA) with 3.54 g of polyethylene glycol acting as a catalyst in 1.0 liter of toluene, and treated with ultrasound for 5 minutes. After removal from the ultrasonic bath, the spheres are rinsed with distilled water and dried at 130°C for 60 minutes. This type of coating is hydrophilic and is suitable, for example, for the removal of polycarbonate (PC) or polyamide (PA) fine particles from water.

[0068] Example 2: To produce a filter medium from spheres arranged in a didisperse spherical packing configuration, SiO2 spheres with a diameter of 1.0 mm and SiO2 spheres with a diameter of 0.225 mm are rinsed with ethanol, dichloromethane, and deionized water for purification. Then, polytetrahydrofuran (THF) is mixed with dichloromethane in a 1:1 ratio and stirred using a so-called vortex mixer. This mixture is then mixed with 7 vol% trifluoroacetic acid (based on the volume of the mixture), and the purified spheres are immersed in it for 10 minutes for coating. After purification with ethanol, the coated spheres are dried at 130°C for 30 minutes. This type of coating has an electric dipole moment and is suitable for removing materials such as polycarbonate (PC) and polyamide (PA).

Claims

1. A filter (1) for removing microscale or nanoscale plastic particles (6) from water, The filter medium (3; 3a) through which the water can pass is provided. The filter medium (3; 3a) has spheres (4, 5, 14-17; 4a, 5a, 14a-17a), each sphere (4, 5, 14-17; 4a, 5a, 14a-17a) has a layer (7) configured to receive the plastic particles (6), the layer (7) is formed such that the surface of the spheres (4, 5, 14-17; 4a, 5a, 14a-17a) is covered with a coating material, and the spheres (4, 5, 14-17; 4a, 5a, 14a-17a) are arranged in a didisperse sphere-filling configuration in which spheres having a first diameter d2 and spheres having a second diameter d1 are mixed with each other, characterized in that the filter (1).

2. The filter according to claim 1, characterized in that the packing density of the spheres (4, 5, 14-17; 4a, 5a, 14a-17a) is between 55 vol% and 90 vol%.

3. The second diameter d1 is greater than the first diameter d2, and the first diameter d of the sphere (5, 15, 17; 5a, 15a, 17a) ２ The second diameter d of the spheres (4, 14, 16; 4a, 14a, 16a) １ Ratio K ｄ The filter according to claim 1, characterized in that the value is between 0.10 and 0.

35.

4. The filter according to claim 1, characterized in that the second diameter d1 is larger than the first diameter d2 and is between 0.95 mm and 1.05 mm.

5. The second diameter d1 is greater than the first diameter d2, and the volume ratio p of the spheres (4, 14, 16; 4a, 14a, 16a) to the total volume of spheres in the filter medium (3; 3a) １ The volume ratio of the spheres (5, 15, 17; 5a, 15a, 17a) to the total volume of spheres in the filter medium (3; 3a) is p ２ Ratio K ｐ The filter according to claim 1, characterized in that the value is between 0.4 and 0.

9.

6. The filter according to claim 1, characterized in that the filter medium (3; 3a) has a length between 3 cm and 12 cm in the flow direction of the filter (1).

7. The filter according to claim 1, characterized in that the volumetric flow rate at which water can flow through the filter (1) is between 4 l / min and 15 l / min.

8. The filter according to claim 1, characterized in that the spheres (4, 5, 14-17; 4a, 5a, 14a-17a) have an activatable surface that can strengthen the bond with the coating material.

9. The filter according to claim 1, characterized in that the layer (7) is formed from a hydrophobic or hydrophilic material, or the layer has an electric dipole moment and is formed from a material selected from the group consisting of polytetrahydrofuran, polymethyl methacrylate, and zeolite.

10. The filter according to claim 1, wherein the layer (7) has a π-conjugated system and contains a material selected from the group consisting of activated carbon, graphene, organic zeolite, and polycyclic aromatic hydrocarbons.

11. The filter according to claim 1, characterized in that the filter medium (3; 3a) has a plurality of regions (11-13), the plurality of regions (11-13) are arranged in a sequence in the flow direction of the filter (1), and each region (11-13) is configured to remove specific plastic particles (6) from the water by coating the spheres (4, 5, 14-17; 4a, 5a, 14a-17a) with a different layer (7) for each region.

12. Apparatus for water treatment (2), comprising a filter (1) according to any one of claims 1 to 11.

13. The apparatus according to claim 12, characterized in that the apparatus (2) is operable by hydrostatic pressure or the pipe pressure of the building's water pipes.

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