Composite material for mechanical filtration and chemical binding of substances, bacteria and viruses from solutions - Patents.com

Abstract

The present invention relates to a composite material suitable for both mechanical filtration and chemical / selective binding / exclusion / removal of substances from a solution. The present invention further relates to the use of said composite material as a filtration membrane. The present invention therefore also relates to a filtration membrane comprising the composite material according to the invention, such as the use of the filtration membrane for purifying a liquid and / or for separating substances from a liquid and / or for removing bacteria or viruses from a liquid.

Description

[Technical field]

[0001] The present invention relates to a composite material suitable for both mechanical filtration and chemical / selective binding / exclusion / removal of substances from liquids / solutions. The present invention further relates to the use of said composite material as a filtration membrane. The present invention therefore also relates to a filtration membrane comprising the composite material according to the invention, such as the use of the filtration membrane for purifying liquids and / or for separating substances from liquids and / or for removing bacteria or viruses from liquids. [Background technology]

[0002] The removal, extraction or recovery of metals, especially heavy metals, or organic substances such as steroids or antibiotics from liquids, such as industrial wastewater from electrolysis operations, from catalyst residues from the petrochemical or pharmaceutical industries, from mine waters, for example from mines, as well as the remediation of soils contaminated with heavy metals, is becoming an increasingly important problem.

[0003] The reason is the negative impact these substances have on the environment. However, there are also economic benefits, especially in the recovery of metals. This means that, on the one hand, environmental aspects are at the forefront, but on the other hand, there is also great interest in the supply of valuable metals, whose availability is becoming increasingly questionable, i.e., their prices are rising. Another important field of application of materials for the removal, extraction or recovery of metals or heavy metals is the separation of metals or heavy metals in drinking water treatment and in seawater desalination.

[0004] The separation of heavy metals from concentrated salt solutions, such as those used in chlor-alkali electrolysis and similar processes, has also received considerable attention.

[0005] Currently, different methods are used to obtain metals from aqueous solutions for different purposes. The most common method is to precipitate the metals by changing the pH value to a range where the metals are no longer soluble. This method requires the addition of precipitants and flocculants and produces amorphous precipitates with a very low metal content, which are contained in an indeterminate and highly volatile mixture. As a rule, these sludges are sent to final disposal and are no longer suitable for further use.

[0006] In some cases, a type of classical separation process is carried out on an industrial scale, in which a precipitate is produced which must be repeatedly decomposed and subjected to further purification steps.

[0007] Removal of metals present only in low concentrations is not possible or uneconomical using this method (equilibrium constants, solubility). Separation of individual metal elements is not possible with the processes currently used.

[0008] Alternative processes use ion exchangers or other absorption resins, which are characterized by low capacity, insufficient stability and life span. They have little selectivity and are therefore not suitable for recovering metals from low concentration solutions. At the same time, the bonds with the most valuable metals are significantly disrupted by harmless salts such as sodium chloride. The binding mechanism in the aforementioned phases is based on simple ion exchange and is accompanied by all the major drawbacks such as interference by organic components, low capacity, sensitivity to other ion mixtures, short life span, degradation, low or lack of selectivity, lack of hygiene or restorability, etc.

[0009] There are several sources of phases based on complex formation of binding behavior. The phases known so far are used for pretreatment of pre-cleaned solutions in chlor-alkali electrolysis, but due to their complex manufacturing methods and delicate structure they are not suitable for the intended field of application. They also have relatively low capacities. At the same time, this method can only process small flows. In addition to the inability to detect metals even in low concentrations, the lack of throughput is currently the main obstacle preventing the implementation of such methods.

[0010] Others, such as electrochemical membrane processes, are so energy intensive that they are only suitable for extracting secondary raw materials from already very clean sources, and therefore are not suitable for treating polluted wastewater.

[0011] In addition to the aforementioned heavy metals, the removal of bacteria and viruses from drinking water is also a problem of increasing importance. In this case, membranes are used that mechanically remove bacteria from the water due to their pore structure. Viruses cannot usually be removed due to their small size. Purely mechanical removal of bacteria can lead to the subsequent formation of a biofilm in which the bacteria can continue to grow and contaminate the water. Bacteria usually pass through the membrane and grow in a short time, making permanent use impossible, even with frequent backwashing.

[0012] Other methods of killing bacteria include the addition of toxic chemicals such as chlorination or antibiotics, treatment with ozone, or irradiation with UV light. The drawback of these methods is that they add toxic chemicals that either impair the taste of the water and require significant effort to remove, or cause undesirable side effects such as promoting antibiotic resistance. Furthermore, some of these methods are very energy intensive or generally not very effective.

[0013] The present invention is therefore based on the problem of removing or killing bacteria and viruses from a solution and at least partially binding the resulting fragments.

[0014] In addition to heavy metals, bacteria and viruses, micropollutants such as perfluorinated surfactants are also an issue of increasing importance. Perfluorinated surfactants enter the environment through release from outdoor clothing cleaning fluids and industrial processes, where they are poorly degraded. As a result, they accumulate in the environment and, over time, can enter the food cycle of humans and animals via food, causing considerable damage.

[0015] Thus, the present invention further sets out the problem of rapidly and effectively removing trace contaminants, such as perfluorinated surfactants, from water or other solvents.

[0016] The shortcomings of established procedures are summarized below. - Small capacity -No or insufficient selectivity -Intolerance to high concentrations of concomitant substances -Low stability and short life span -High energy consumption -Low throughput -Not applicable to low concentration solutions -Difficult to reuse - Requires complex pre-cleaning procedures -It is a multi-stage separation process that repeats the precipitation and digestion stages.

[0017] It would be advantageous if, in addition to this purification mode, it were possible to simultaneously perform a purely mechanical filtration of the liquid to be purified in conjunction with the chemical or selective binding, rejection or exclusion of metals or other substances as contaminants. In this way, particulate contaminants or aggregates can be separated from the liquid by purely mechanical filtration, and in addition, smaller components that were not separated by the filtration of the liquid to be purified can be removed from the liquid by chemical or selective absorption, rejection or exclusion. Up to now, for this purpose, porous membrane materials are known in which pre-produced polymer microgel particles are introduced. By pre-producing the polymer microgels, gels of a certain particle size are obtained. Depending on the corresponding particle size, these gels can only be introduced into the pores of the membrane material or its support structure that are large enough to accommodate the microgel particles. This has the disadvantage that the chemical absorption performance of such systems is not satisfactory, since in the corresponding systems a large proportion of the pore volume is not filled with microgel. Furthermore, known membrane materials with microgel particles in the pores of the support structure are usually materials whose separation or absorption properties are highly temperature-dependent or whose capacity is highly temperature-dependent. This is also undesirable. Summary of the Invention [Problem to be solved by the invention]

[0018] It is therefore an object of the present invention to provide a composite material that can effectively combine and simultaneously realize the advantages of mechanical filtering and chemical or selective binding / removal / exclusion of substances, thereby allowing the removal of metals or substances from aqueous and non-aqueous acidic, basic or neutral solutions at low and high concentrations. It is also an object of the present invention to simultaneously remove metals or heavy metals from solutions with high alkaline metal loadings.

[0019] Additionally, killing bacteria and viruses, as well as removing certain trace contaminants such as perfluorinated surfactants, are also part of the problem to be solved.

[0020] Preferably, the composite material provided according to the invention is sanitizable, i.e. it allows metals or organic substances to be recovered in a simple manner and allows the composite material to be effectively purified under correspondingly harsh conditions.

[0021] It is a further object of the present invention to provide a composite material capable of treating large volumes of streams with moderate levels of heavy metal contamination in a short period of time where disinfection / filtration is desired. [Means for solving the problem]

[0022] The object of the present invention is achieved by providing a composite material according to the present invention, comprising an organic polymer and a layered material having a pore system with open pores, the open pores extending continuously through the layered material, the open pores on a first side of the layered material having a smaller average pore size than the pores on a second side, the first and second sides being on opposite sides of the layered material, and an organic polymer located within the open pores, the organic polymer being introduced into the pore system from a homogeneous solution and subsequently immobilized.

[0023] The first and second sides of the layered material are the opposite outer sides of the layered material, i.e., the opposite faces of the layered material. The extension vectors of the first and second sides of the layered material are in the extension direction of the layered material and are arranged perpendicular to the thickness vector of the layered material. This arrangement of the layered material therefore allows for flat membranes as well as cylindrical membranes, with cylindrical membranes being preferred in the present invention.

[0024] The layered material has a smaller average pore size on a first side than on a second side of the layered material, so that the first side can act as a filtration membrane, filtering substances or particulate contaminants from a liquid flowing through the layered material by purely mechanical filtration and size exclusion, and because the average pore size on the second side of the layered material is larger, organic polymers can be introduced into the pores of the pore system, so that the second side acts to chemically / selectively bind / exclude / exclude substances.

[0025] To determine the pore size of the first side (membrane side) of the layered material, characterization using dextran standards (similar to reverse size exclusion chromatography) is used. Different solutions of dextran with defined increasing molecular weights are poured from the first side to the second side of the layered material. The size cut-off of the layered material is determined by the width of the pores. That is, as the size of the dextran standards continues to increase, at some point a size is reached (MWCO: molecular weight cut-off) beyond which the layered material cannot pass. In this way, the pore size of the first side of the layered material can be determined. Now, the size of the remaining pores (particularly the pore size of the second side of the layered material) can be determined by comparison by using SEM images (SEM: scanning electron microscope). Alternatively, the average pore size of the first and second sides can also be determined absolutely using SEM only, by taking and evaluating SEM images of both sides of the layered material. The increase in pore size of the material from the first side to the second side of the layered material can be shown by SEM images of the cross section.

[0026] The organic polymer introduced into the pore system of the layered material preferably has the property of being a polymer capable of chemical / selective absorption or repulsion, i.e. an absorbent polymer. The organic polymer is preferably a hydrophilic polymer. When the composite material is used for liquid purification, the direction of flow of the liquid is preferably from the first side to the second side of the layered material. When the organic polymer is a hydrophilic polymer, the relatively hydrophilic surface of the layered material facilitates the elution of lipophilic residues retained by size exclusion of the membrane, thereby contributing to improving the antifouling properties of the membrane. This increases the productivity of the membrane, since the number of backwash cycles and backwash volumes used are reduced.

[0027] By introducing an organic polymer, preferably a linear polymer, into the pore system from a homogeneous solution in which the polymer is dissolved, smaller pores can be coated or filled with the organic polymer than if the polymer was already present in the form of hydrogel / microgel particles prior to introduction. In this way, a more uniform coating or filling of the pores or surfaces of the pores is achieved, resulting in an increased capacity.

[0028] The subsequent immobilization of the polymer introduced into the pore system is aimed at binding the organic polymer to the layered material. The immobilization can be achieved by crosslinking the organic polymer introduced into the pore system. However, the immobilization or fixation of the polymer can also be achieved by covalently bonding the organic polymer to the layered support material. Another possibility according to the invention is the immobilization / fixation of the organic polymer to the layered support material by adsorptive and / or ionic interactions.

[0029] When the organic polymer is immobilized / fixed by crosslinking, this can be achieved by using a crosslinking agent that is applied after the organic polymer is introduced into the pore system, that is introduced together with the organic polymer, or that is already present in the pore system. In the latter case, the crosslinking agent is preferably applied to the layered material by drying, in which the crosslinking agent dissolved in a solvent is introduced into the pore structure of the layered material, and the solvent is subsequently removed by evaporation, so that the crosslinking agent is present on the surface of the pores. The organic polymer to be crosslinked can then be introduced into the pore structure by the method described herein and reacted with the crosslinking agent to form a crosslinked polymer.

[0030] If the organic polymer is immobilized / fixed by crosslinking, it is preferred to have a degree of crosslinking of at least 2%, based on the total number of crosslinkable groups in the organic polymer. More preferably, the degree of crosslinking is in the range of 2.5-60%, more preferably in the range of 5-50%, most preferably in the range of 10-40%, in each case based on the total number of crosslinkable groups in the organic polymer. The degree of crosslinking can be adjusted by the corresponding amount of desired crosslinker. It is assumed that 100 mol % of the crosslinker reacts to form crosslinks. This can be verified by analytical methods such as MAS-NMR spectroscopy or quantitative determination of the amount of crosslinker relative to the amount of polymer used. According to the present invention, this method is preferred. The degree of crosslinking can also be determined by IR spectroscopy, for example for C-O-C or OH vibrations, using a calibration curve. Both methods are standard analytical procedures for the skilled person. If the degree of crosslinking exceeds the specified upper limit, the polymer coating or filling of the organic polymer is not flexible enough, which results in a reduced binding capacity. If the degree of crosslinking falls below the specified lower limit, the polymer coating is not stable enough on the surface or in the pores of the layered material.

[0031] The crosslinking agent has two or more functional groups, and the crosslinking occurs by bonding of these functional groups with the organic polymer. The crosslinking agent used to crosslink the organic polymer is preferably selected from the group consisting of dicarboxylic acids, tricarboxylic acids, aldehydes, ureas, bis- or tris-epoxides, diisocyanates or triisocyanates, with dihaloalkyl, trihaloalkyl or mixed functional molecules (e.g., epichlorohydrin), dicarboxylic acids and bis-epoxides being preferred functional groups. The crosslinking agent is preferably a dicarboxylic acid and a bis-epoxide, such as terephthalic acid, biphenyl dicarboxylic acid, ethylene glycol diglycidyl ether and 1,12-bis-(5-norbornene-2,3-dicarboximide)-decane dicarboxylic acid, the latter two being more preferred. In one embodiment of the present invention, the crosslinking agent is preferably a linear, conformationally flexible molecule having a length between 3 and 20 atoms.

[0032] The preferred molecular weight of the organic polymer is in the range of 5,000 to 5,000,000 g / mol.

[0033] When the organic polymer is immobilized / anchored to the layered material by covalent bonding, the functional side groups of the polymer preferably react with the functional surface groups of the layered material or react with a reactant after the organic polymer is introduced into the pore system of the layered material. The functional surface groups of the layered material can be aliphatic or benzylic carbon atoms that are activated, for example, by bromination. The functional side groups of the organic polymer can be nucleophilic groups, such as, for example, -OH or amino groups, which can then be bonded to the functional surface groups of the layered material.

[0034] When the organic polymer is immobilized / anchored to the layered material by adsorption or ionic interactions, the organic polymer preferably has ionic groups in its side chains that have a complementary charge to the ionic groups on the surface within the pores of the layered material. Such complementary ionic groups can be, for example, -SO3 - and -NH3 + It could be.

[0035] The organic polymer may be a polymer of the same repeating units (polymerized monomers), but may also be a copolymer, preferably having as comonomer a simple alkene monomer or a polar inert monomer such as vinylpyrrolidone.

[0036] Examples of organic polymers that can be introduced into the pore system from a homogeneous solution include polyalcohols, polyamines such as any polyalkylamine (e.g., polyvinylamine and polyallylamine), polyethyleneimine, polylysine, amino group-containing polymers such as Lupamine, etc. Among these, polyalkylamines and polyalkyl alcohols having hydroxyl or amino groups are preferred, polyvinylamine, polyallylamine and lupamine are more preferred, and polyvinylamine and lupamine are particularly preferred.

[0037] After the organic polymers are introduced into the pore system of the layered carrier material and the subsequent immobilization of the polymer, the polymer is preferably in the form of a so-called hydrogel. In this case, hydrogel is understood to mean a polymer that comprises a solvent (preferably water) but is soluble in the solvent, the molecules of which are chemically linked, for example by covalent or ionic bonds, or physically linked, for example by entanglement of the polymer chains, thereby forming a three-dimensional network. Due to the incorporation of polar (preferably hydrophilic) polymeric components, the polymers swell in the solvent (preferably water) and increase significantly in volume (depending on crosslinking), but without losing the cohesion of the material. The organic polymers introduced into the pore system of the layered material are present as hydrogels in the composite material according to the invention, in particular when swollen in the solvent, i.e. in particular during the use of the composite material as described below.

[0038] The use of polymers containing hydroxyl or amino groups as organic polymers also has the advantage that organic residues can be introduced into the side chains of the polymer on the oxygen or nitrogen of the hydroxyl or amino groups, which organic residues can form specific interactions with the substances to be purified or with heavy metals. Such organic residues are preferably residues with Lewis base properties. In this way, functionalization of the organic polymer can be carried out, but this functionalization preferably occurs only after the organic polymer has been immobilized in the pore structure of the layered material.

[0039] Amino-group-containing polymers also have the advantage that they have an antibacterial effect (DE 102017007273 A1), making it possible not only to remove bacteria and viruses by size exclusion but also to kill them directly.

[0040] The organic polymer is introduced into the pore system by creating a homogeneous solution of the organic polymer which is then introduced into the pore system. This can be done using known wet chemical impregnation processes, but can also be achieved by a so-called flow-through process, in which a solution containing the organic polymer is pumped through the composite material.

[0041] The so-called dip-coating and pore-filling methods are known wet chemical impregnation processes. In dip-coating, the layered material is immersed for a certain time in a homogeneous solution of an organic polymer, and the pore space is filled with this solution by capillary forces. Both pure water or aqueous media and organic solvents such as dimethylformamide can be used as solvents.

[0042] A layered material can be composed of a single layer or multiple layers. A "single layer" of a layered material means a layered material in which the components leading to the first and second sides are composed of the same material except for the pore size. In this case, the average pore size can increase continuously from the first side of the layered material to the opposite second side of the layered material, but it can also increase abruptly. In the latter case, such an abrupt increase occurs by joining two layers of the same material with different average pore sizes. A "two or more layers" of a layered material refers to two different layers made of different materials, of which the material on the first side has a smaller average pore size than the material on the opposite second side. Again, the pore size can increase abruptly or continuously.

[0043] The component of the layered material located on the first side with the smaller average pore size is also called the membrane material, since this material is preferably responsible for the mechanical filtration in the composite application due to its relatively small pore size. In other words, the component of the layered material on the first side constitutes the membrane. This first side is therefore also called the membrane surface.

[0044] The constituent elements of the layered material that give rise to the relatively large average pore size on the second side may also be referred to as a so-called support structure for the constituent elements of the first side (membrane material) of the layered material. Preferably, the average pore size of the pores on the second side of the layered material is in the range of 6 nm to 20,000 nm, more preferably in the range of 10 nm to 12,000 nm, and even more preferably in the range of 20 nm to 5,000 nm.

[0045] The layered material preferably has a thickness in the range of 500 μm to 10 cm, more preferably in the range of 600 μm to 5 cm, and most preferably 700 μm to 2 cm.

[0046] More preferably, the average pore size of the first side is at least 3% smaller than the average pore size of the second side, more preferably at least 7% smaller, and even more preferably at least 12% smaller. If the average pore size of the second side is too small, it becomes difficult to fill the pore system with the organic polymer. Further disadvantages include higher membrane back pressure, lower permeability, more frequent backwashing, and limited regenerability.

[0047] Whether the layered material is comprised of one or more layers, each of these layers may independently be a crosslinked organic polymer, an inorganic material, or a mixture thereof.

[0048] Suitable inorganic materials as used herein are also known as monoliths, ceramic membranes or ceramic monoliths and may be designed, inter alia, as flat or hollow cylinders.

[0049] The crosslinked organic polymer is preferably selected from the group consisting of polyalkyls, preferably polyalkyls with aromatic moieties in the side chain (i.e. attached to the polyalkyl chain), polyethersulfones, polyacrylates, polymethacrylates, polyacrylamides, polyvinyl alcohols, polysaccharides (e.g. starch, cellulose, cellulose esters, amylose, agarose, sepharose, mannan, xanthan gum and dextran) and mixtures thereof. Most preferably, the crosslinked organic polymer is polystyrene or polyethersulfone or a derivative thereof, such as a copolymer of polystyrene and divinylbenzene. When the crosslinked organic polymer comprises aromatic units, it is preferred that the crosslinked organic polymer is sulfonated. In a particularly preferred embodiment of the invention, the crosslinked organic polymer is polyethersulfone.

[0050] In a further preferred embodiment, porous and non-porous polymer monoliths made of perfluorinated polymers (e.g., PTFE, TPE, PVF, PVDF, PCTFE or PFA copolymers, and related polymers and biopolymers made, for example, of lignin or cellulose) are used.

[0051] When the layer of the layered material is an inorganic material, the inorganic material is preferably an inorganic mineral oxide selected from the group consisting of silicon oxide, aluminum oxide, magnesium oxide, titanium oxide, zirconium oxide, nitrides or carbides of the above oxides, fluorosil, magnetite, zeolite, silicates (e.g., diatomaceous earth), mica, hydroxyapatite, fluoroapatite, organic metal basic structures, ceramics, glass, porous glass (e.g., Trisoperl), metals (e.g., aluminum, silicon, iron, titanium, copper, silver and gold), graphite and amorphous carbon. Particularly preferably, the inorganic material is one of the above mineral oxides, aluminum oxide and titanium oxide.

[0052] The individual layers or layers of the layered material may (each independently of the other) be of homogeneous or heterogeneous composition, and therefore specifically also include materials that are composed of one or more of the above materials.

[0053] The layered materials can be obtained by the processes described in DE102005032286A1, EP2008704A1, WO2006 / 012920A1, DE60016753T2 and DE69935893T2.

[0054] In a further embodiment, the present invention also relates to a filtration membrane comprising the composite material according to the invention or composed of the composite material according to the invention. The filtration membrane may have the shape of a flat membrane, a tubular membrane or a hollow fiber membrane, with hollow fiber membranes being more preferred according to the present invention, since they allow a simpler filtration device and have less fiber breakage compared to flat membranes, and therefore a relatively high throughput. In the case of hollow fiber membranes, the composite material according to the present invention is arranged in the form of a tube, with a first side of the layered material being located inside the tube and the opposite second side representing the outer surface of the tube. A number of such tubes can also be arranged side by side, so that an even higher throughput can be achieved during use. Corresponding hollow fiber membranes are known in the prior art and are identified in the aforementioned publications.

[0055] In a further embodiment, the present invention also relates to a method for producing a composite material according to the invention, in which a layered material having a pore system with open pores extending continuously through the layered material is treated with a homogeneous solution of an organic polymer. All the features of the above-mentioned process for producing a composite material according to the invention are therefore also part of the process according to the invention. The same applies to the components mentioned in connection with the composite material according to the invention.

[0056] The invention also relates in particular to the use of the composite material according to the invention as a filtration membrane.

[0057] Furthermore, the present invention also relates to the use of a filtration membrane according to the invention for purifying a liquid and / or for separating substances, preferably suspended, dissolved or colloidal substances, from a liquid.A particularly preferred use of the filtration membrane is the use of the filtration membrane according to the invention for separating metals / metal compounds and / or organic substances, such as, for example, steroids, antibiotics, etc., from a liquid, in particular which should not get into groundwater or whose concentration in the groundwater should not exceed certain limit values.

[0058] According to the present invention, the liquid from which the metal / metal compounds and / or organic materials are to be bound can be aqueous and non-aqueous acidic, basic or neutral liquids or solutions in low and high concentrations.

[0059] The metal / metal compound to be separated in the use according to the invention is preferably a metal that is present in the abovementioned solution in ionic form or also as a metal-ligand coordination compound in ionic form. The metal is preferably a complexing metal, i.e. a metal that can form a metal-ligand coordination bond. More preferably, the metal is a transition metal or a rare earth metal, even more preferably a noble metal or a rare earth. Particularly preferred are the metals copper, nickel, lead and chromium.

[0060] In a further embodiment of the use according to the invention, the liquid from which metals are to be bound is a liquid to be purified in bulk streams, such as drinking water and surface water.

[0061] Furthermore, the liquid from which the metal is to be bound is preferably an aqueous solution having a pH in the range of 3-10, more preferably 5-9, and even more preferably 6-8.

[0062] To bind the metals from the liquid, the metal-containing liquid is pumped through the filtration membrane, preferably from the first side to the second side of the layered material. By providing the composite material of the invention or the filtration membrane of the invention, the chelated metals can not only be removed from the liquid, but can also be recovered by leaching. By using the filtration membrane of the invention, significant concentrations of the purified substances or metals are generated on the functionalized membrane, resulting in manageable amounts that can be used for further economical processing. This means that the circular economy is open to very large volumes of streams containing low concentrations of valuable heavy metals.

[0063] Furthermore, the present invention allows for simultaneous filtration of impurities and chemical removal of organics or metals by adsorption / complexation. High fluxes are maintained by using the composite material of the present invention as a filtration membrane. Effect of the Invention

[0064] The main advantage of the present invention is the discharge of wastewater contaminated with low heavy metals with simultaneous ultrafiltration and disinfection, as well as the targeted removal of trace pollutants through the use of specially functionalized polymers. The present invention therefore fills a technological gap that cannot be addressed with particulate chelating gels. Particulate systems (columns, cartridges) have significant pressure drops that significantly limit the throughput of the solution volume per unit time. Thus, when using particulate absorbents, very large systems are required. This limitation is eliminated with the composite material of the present invention as a filtration membrane, and large flows can be achieved in a very short time with systems that are much smaller than those that would need to be designed with particulate systems.

[0065] Thus, the present invention provides the following advantages: -Combines mechanical purification of the water stream, removal of heavy metals / undesirable substances and disinfection -High volumetric throughput of contaminated solution per unit of time and size of system -Membrane systems are technically well established worldwide on a very large scale -Long service life -Excellent mechanical and chemical robustness -Easy regeneration and extraction of metals [Brief description of the drawings]

[0066] The invention will now be described using the following figures and examples, which should be considered as merely illustrative. [Figure 1] FIG. 1 shows a cross-section of a layered material (1) having a first side (2) and a second side (3) opposite the first side. [Diagram 2]Figure 2 shows a filtration membrane according to the invention, designed as a hollow fiber membrane (4), which is made up of a composite material according to the invention. As can be seen from the references (1), (2) and (3), the side of the composite material with the smaller average pore size is located on the inside of the hollow fiber membrane, and the side with the larger average pore size is located on the outer surface. [Diagram 3] FIG. 3 shows the detection of effluents in a hollow fiber membrane made of a composite material according to the invention according to Example 1 compared to an uncoated hollow fiber membrane. [Figure 4] FIG. 4 shows the isotherms recorded when testing a hollow fiber membrane made of a composite material according to the invention according to Example 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS EXAMPLES

[0067] Example 1: Production of a composite material according to the invention in the form of a hollow fiber by the so-called flow-through process: A PES hollow fiber (PES: polyethersulfone) with an average pore size of 20 nm inside the fiber, an average pore size of 1 μm outside, an outer diameter of 4 mm, and 7 internal channels, each with a diameter of 900 μm, embedded in a 25 cm long tube, is prepared for coating by rinsing with 100 ml of deionized water, methanol, and again with deionized water. A solution of 2.0 g of hydrolyzed Lupamine 4500 (10% m / m) in 50 ml of deionized water is then pumped through the hollow fiber. The aqueous solution is then removed by suction from the hollow fiber and the tube, and a solution of 100 mg of ethylene glycol diglycidyl ether in 100 ml of isopropanol is pumped through the hollow fiber. This solution is pumped in a circulatory manner, with a total pumping volume of 500 ml. Upon completion, aspirate off excess solution and rinse the fibers with 50 mL each of isopropanol, methanol, deionized water, 1 mol / L HCl(aq), deionized water, 1 mol / L NaOH(aq), 1 mol / L NaOH(aq), and deionized water, in that order.

[0068] Example 2: Production of a composite material according to the invention in the form of a hollow fiber by so-called wet-chemical coating: Seven pieces of PES hollow fiber as in Example 1, 5 cm in length, are washed three times in 100 mL deionized water and then treated on an overhead shaker in a solution of 6 g hydrolyzed Lupamine 4500 (10% m / m) in 150 mL deionized water for 24 hours. The supernatant solution is then decanted off and the pieces are washed twice with 50 mL isopropanol each, whereby the supernatant solution is also decanted off. The pieces are now treated on an overhead shaker in a solution of 300 mg ethylene glycol diglycidyl ether in 100 mL isopropanol for 24 hours. Upon completion, the supernatant is discarded and the pieces are post-treated by washing in that order with 50 mL each of isopropanol, methanol, deionized water, 1 mol / L HCl (aq), deionized water, 1 mol / L NaOH (aq) and deionized water.

[0069] Example 3: Testing of the composite material according to Example 1: A 1 g / L CuSO4*5H2O aqueous solution is pumped through the bypass at a flow rate of 1 mL, thereby obtaining a baseline. After 10 minutes, the flow is switched to the hollow fiber membrane according to Example 1 by switching the valve, and this flow is cast into a single module. The effluent is detected by UV at 790 nm (absorption copper-water complex). When the module is saturated with copper, there is an immediate leakage of the metal, which is detected by its absorption. The amount of copper absorbed into the membrane is determined by comparing with the corresponding reference surface.

[0070] The same is done with hollow fiber membranes similar to those of Example 1, but not coated with the polymer according to Example 1.

[0071] The 1% leakage of the coated membrane is 10 min slower than that of the uncoated membrane. This corresponds to a copper uptake of about 40 mg / m2 membrane. A gradual increase is also observed. Both of these results indicate the binding of copper from the solution to the coated phase. When the dead volume of the module is filled (after about 5 min), leakage of the uncoated phase occurs. The detection of the effluent is shown in Figure 3.

[0072] Example 4: Testing of the composite material according to Example 2: Seven pieces of membrane prepared using the same absorption process (Example 2) are incubated with seven different solutions of increasing copper sulfate concentrations for 24 hours. The supernatant is separated and the concentration of unbound copper in the solution is measured photometrically at a wavelength of 790 nm. The amount of absorbed copper is calculated and an isotherm is determined (Figure 4). This shows that the coated membrane binds at 20 mg / m membrane at the highest concentration tested. The evolution of the isotherm shows that the maximum loading has not yet been reached.

[0073] Example 5: Coating of inorganic monoliths A 10-inch hollow cylinder with a wall thickness of 1 cm made of porous ceramic with an average pore diameter of less than 5 μm is washed in 10 L of deionized water in both flow directions and then incubated for 24 hours on an overhead shaker in a solution of 200 g of hydrolyzed Lupamine 4500 (10% m / m) in 800 mL of deionized water. The supernatant solution is then decanted and the hollow cylinder is rinsed twice with 2 L of isopropanol each. The hollow cylinder is then treated for 24 hours on an overhead shaker in a solution of 8 g of ethylene glycol diglycidyl ether in 990 mL of isopropanol. Upon completion, the supernatant is discarded and post-processing is performed by washing with 5 L each of isopropanol, methanol, deionized water, 1 mol / L HCl (aq), deionized water, 1 mol / L NaOH (aq) and deionized water, in that order.

Claims

1. A composite material comprising an organic polymer and a layered material (1) having a pore system with open pores, wherein the open pores extend continuously through the layered material, and the pores on the first side (2) of the layered material have a smaller average pore diameter than the pores on the second side (3) opposite the first side, wherein the organic polymer is located within the open pores, and the organic polymer is introduced into the pore system from a homogeneous solution and subsequently immobilized. A composite material characterized by this.

2. The composite material according to claim 1, wherein the organic polymer is an absorbent polymer.

3. The composite material according to claim 1, wherein the organic polymer is a hydrogel.

4. The composite material according to claim 1, wherein the organic polymer is a polymer containing a hydroxy group or an amino group that may further contain additional organic residues in the side chain.

5. The composite material according to claim 1, wherein the organic polymer is bonded to the composite material by crosslinking bonds and / or covalent bonds, adsorption bonds and / or ionic bonds.

6. The composite material according to claim 1, wherein the average pore diameter of the pores on the first side is in the range of 6 nm to 20000 nm.

7. The composite material according to claim 1, wherein the average pore diameter on the first side is at least 3% smaller than the average pore diameter on the second side.

8. The composite material according to claim 1, wherein the layered material is composed of one or more layers that can independently be an organic polymer or an inorganic material.

9. The composite material according to claim 1, wherein the layered material is in the shape of an organic or inorganic monolith.

10. Use of the composite material according to any one of claims 1 to 9 as a filtration membrane.

11. A filtration membrane comprising the composite material according to any one of claims 1 to 9.

12. The filtration membrane according to claim 11, having the shape of a flat membrane, a tubular membrane or a hollow fiber membrane (4).

13. Use of the filtration membrane according to claim 11 for purifying a liquid and / or for separating substances from a liquid.

14. The use according to claim 13 for separating metal / metal compounds and / or organic substances from a liquid.

15. The use according to claim 13 for removing bacteria or viruses from a liquid.

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