A treatment system for preparing drinking water

Abstract

The present invention belongs to the field of drinking water treatment, and relates to a treatment system for preparing drinking water, including a water inlet device, a filter device and an immersed flat membrane filtration device arranged in sequence. The immersed flat membrane filtration device includes a membrane stack, and the membrane stack includes a plurality of membrane bag units, and the membrane bag unit includes a flat membrane. The raw material for preparing the flat membrane is a polymer doped with a negatively charged microporous framework material. The raw materials for preparing the negatively charged microporous framework material include 4,6-dicyanoresorcinol, 1,4-butane sultone, and potassium salt. The negatively charged microporous framework material of the present invention has a rigid microporous structure, which can increase the water permeation channel in the flat membrane, and can also form a through structure with the membrane pores in the flat membrane, effectively shortening the water transmission path and improving the membrane flux. In addition, the negatively charged microporous framework material also has negative charge, has a repelling effect on pollutants in the water body, can prevent pollutants from entering the pore size of the flat membrane, and reduce the fouling phenomenon on the flat membrane.

Description

Technical Field

[0001] The invention relates to the technical field of drinking water treatment, and in particular to a treatment system for preparing drinking water. Background Art

[0002] Water treatment systems are important infrastructure to ensure water quality safety and environmental protection, and are widely used in drinking water purification. As a key infrastructure to ensure water quality safety, drinking water treatment systems play an irreplaceable role in maintaining public health and promoting social and economic development. Drinking water treatment systems are used to convert raw water into water that meets drinking standards. Common raw water includes surface water such as rivers and lakes, as well as groundwater. Although surface water is abundant, it is easily affected by factors such as agricultural runoff and industrial wastewater discharge, and contains more suspended matter, organic matter, pathogenic microorganisms and other pollutants. Groundwater is usually cleaner, but some areas may have problems such as nitrates, fluorides, and excessive heavy metals. The drinking water treatment system uses a series of physical, chemical and biological treatment technologies to remove or reduce microorganisms, organic matter, inorganic matter, heavy metals and pesticide residues that may exist in raw water to protect public health.

[0003] Flat membrane filtration devices have the advantages of good mechanical properties, strong impact load resistance, simple equipment, and easy membrane operation and replacement. They are often used in the purification of drinking water.

[0004] The existing flat membrane filtration device has the following two main problems during use:

[0005] First, in order to ensure good treatment effects, the pore size of existing flat membranes is generally small. Although the smaller pore size design improves the filtration effect of the flat membrane, it also increases the resistance of fluid passage, making the membrane flux of the flat membrane generally small. The smaller membrane flux results in a limited amount of water that the flat membrane can process per unit time, which prolongs the treatment cycle and reduces the efficiency of the drinking water treatment system.

[0006] Second, the particles, colloid particles and organic matter in the raw water will be adsorbed, deposited and aggregated on the surface of the flat membrane or inside the membrane pores. This phenomenon will cause the pore size of the membrane to be blocked, resulting in increased resistance through the membrane and a continuous decrease in membrane flux, affecting the treatment efficiency and service life of the flat membrane filtration device, and further affecting the treatment efficiency and effluent quality of the drinking water treatment system.

[0007] In order to solve the problem of low membrane flux, the existing technology increases the membrane flux by increasing the pore size of the flat membrane to improve the drinking water treatment efficiency. However, increasing the pore size of the flat membrane will reduce its filtering effect and affect the effluent water quality.

[0008] For the fouling problem, the membrane surface of the flat membrane is generally modified, such as grafting modification, to reduce the fouling phenomenon of the flat membrane. Although the modification of the membrane surface can reduce the fouling of the membrane to a certain extent, the stability of the anti-fouling function of the modified membrane is not good. After a certain period of operation, the pollutants will still be enriched on the flat membrane to cause fouling of the membrane. Therefore, the modification method cannot effectively reduce the fouling phenomenon of the flat membrane.

[0009] Therefore, it is necessary to effectively increase the membrane flux of the flat membrane, reduce the fouling of the flat membrane, and improve its filtration efficiency. Summary of the invention

[0010] 1. Technical issues to be resolved

[0011] In view of the above technical problems, the present invention provides a treatment system for preparing drinking water, which can effectively increase the membrane flux of the flat membrane, reduce the fouling of the flat membrane, and improve the filtration efficiency.

[0012] (II) Technical solution

[0013] In order to achieve the above object, the main technical solutions adopted by the present invention include:

[0014] The present invention provides a treatment system for preparing drinking water, comprising a water inlet device, a filter device and an immersed flat membrane filtration device arranged in sequence; the immersed flat membrane filtration device comprises a membrane stack, the membrane stack comprises a plurality of membrane bag units, and the membrane bag unit comprises a flat membrane;

[0015] The raw material for preparing the flat membrane is a polymer doped with a negatively charged microporous framework material;

[0016] The raw materials for preparing the negatively charged microporous framework material include 4,6-dicyanoresorcinol, 1,4-butane sultone, and potassium salt.

[0017] As described above, in the treatment system for preparing drinking water, preferably, the method for preparing the negatively charged microporous framework material comprises the following steps:

[0018] S1: reacting 4,6-dicyanoresorcinol, 1,4-butane sultone and potassium salt at 110-130° C. for 10-15 h to obtain potassium 4,4′-(4,6-dicyano-1,3-diphenoxy)dibutanesulfonate;

[0019] S2: Potassium 4,4'-(4,6-dicyano-1,3-diphenoxy)dibutanesulfonate is reacted with 4,6-dicyanoresorcinol at 60-80° C. for 5-7 hours to obtain a negatively charged microporous framework material.

[0020] The treatment system for preparing drinking water as described above, preferably, in step S1, 4,6-dicyanoresorcinol, 1,4-butane sultone and potassium salt are added to a first organic solvent, and reacted at 110-130° C. for 10-15 hours to obtain potassium 4,4'-(4,6-dicyano-1,3-diphenoxy)dibutanesulfonate; the potassium salt is potassium carbonate, the first organic solvent is N,N-dimethylacetamide, and the molar ratio of 4,6-dicyanoresorcinol, 1,4-butane sultone and potassium salt is 1:(2.2-2.5):(2.5-3.5);

[0021] In step S2, potassium 4,4'-(4,6-dicyano-1,3-diphenyloxy)dibutanesulfonate and 4,6-dicyanoresorcinol are added to a second organic solvent and reacted at 60-80° C. for 5-7 hours to obtain a negatively charged microporous framework material; the molar ratio of potassium 4,4'-(4,6-dicyano-1,3-diphenyloxy)dibutanesulfonate to 4,6-dicyanoresorcinol is 1:2-1:3, and the second organic solvent is trifluoromethanesulfonic acid;

[0022] The polymer is one or a mixture of polyethylene, polypropylene, polysulfone, polyethersulfone and polyvinylidene fluoride;

[0023] The negatively charged microporous framework material accounts for 0.5-25% of the mass of the polymer.

[0024] In the treatment system for preparing drinking water as described above, preferably, the membrane bag unit further comprises a liner mesh arranged between the flat membranes; the liner mesh is a polyvinyl chloride mesh or a polypropylene mesh;

[0025] The surface of the inner lining separator is coated with a hydrophilic polymer containing a nano-catalytic material; the nano-catalytic material accounts for 0.05-8% of the mass of the hydrophilic polymer;

[0026] The hydrophilic polymer is one or a mixture of polyvinyl pyrrolidone, polyacrylic acid and polyacrylamide.

[0027] In the treatment system for preparing drinking water as described above, preferably, the preparation method of the nanocatalytic material is as follows:

[0028] The cobalt salt and the iron salt are subjected to a hydrothermal reaction at a pH of 8-9 and a temperature of 120-150° C. for 20-30 hours, and then graphene oxide is added and the reaction is continued for 2-4 hours to obtain a nanocatalytic material;

[0029] The molar ratio of cobalt salt to iron salt is 1:1-1:1.5;

[0030] The cobalt salt is one of cobalt nitrate, cobalt chloride, cobalt sulfate and their crystalline hydrates, and the iron salt is one of iron nitrate, iron chloride, iron sulfate and their crystalline hydrates;

[0031] The mass of graphene oxide is 5-10% of the sum of the mass of cobalt salt and iron salt.

[0032] In the treatment system for preparing drinking water as described above, preferably, the porosity of the flat membrane is 40-80%, and the composite photocatalyst and the composite adsorption material are coated on two adjacent flat membranes respectively;

[0033] The preparation method of the composite photocatalyst is as follows:

[0034] At 20-30° C., 3,5-dicyclopentyltriazole, aminophthalide and silver nitrate are reacted in a third organic solvent for 48-72 hours to obtain a silver-triazole-aminophthalide complex, and then the silver-triazole-aminophthalide complex is mixed with titanate to obtain a composite photocatalyst.

[0035] In the treatment system for preparing drinking water as described above, preferably, the molar ratio of 3,5-dicyclopentyltriazole, aminophthalide and silver nitrate is (0.8-1.2):(1-1.4):(0.8-1.2);

[0036] The third organic solvent is a mixed solution of acetonitrile and ethanol, wherein the volume ratio of acetonitrile to ethanol is 1:1;

[0037] The titanate is magnesium titanate or barium titanate.

[0038] In the treatment system for preparing drinking water as described above, preferably, the preparation method of the composite adsorbent material is as follows:

[0039] Adding acetate and hydroxyterephthalic acid into a fourth solvent, reacting at a temperature of 120-160° C. for 16-20 hours to obtain an intermediate product;

[0040] At 70-90° C., adding the intermediate product to pyridine, and then adding tetraethynylpyrene, reacting for 1.5-2.5 hours to obtain a porous adsorption material, and mixing the porous adsorption material with titanate to obtain a composite adsorption material;

[0041] The mass ratio of tetraethynylpyrene to the intermediate product is 1:2-1:3, and the concentration of tetraethynylpyrene in pyridine is 2-5 mmol / L.

[0042] In the treatment system for preparing drinking water as described above, preferably, the acetate is zinc acetate or zirconium acetate, the molar ratio of acetate to hydroxyterephthalic acid is 2:1-3:1, the fourth solvent is N,N-dimethylformamide, and the titanate is magnesium titanate or barium titanate.

[0043] The treatment system for preparing drinking water as described above, preferably, the treatment system further comprises a water production device and a sewage discharge device;

[0044] The submerged flat membrane filtration device also includes a clamping plate for fixing the membrane stack.

[0045] (III) Beneficial effects

[0046] In the treatment system of the present invention, the flat membrane in the immersed flat membrane filtration device adopts a polymer doped with a negatively charged microporous framework material. The negatively charged microporous framework material has a rigid microporous structure, which can increase the water permeation channel in the flat membrane. At the same time, it can also form a through structure with the membrane pores in the flat membrane, effectively shortening the water transmission path, improving the membrane flux, and thus improving the water treatment efficiency.

[0047] In addition to improving membrane flux, negatively charged microporous frame materials also have negative charge. Many organic matter, colloidal particles and microorganisms in the water also have negative charges on their surfaces. When approaching a flat membrane that is also negatively charged, electrostatic repulsion will be generated between the negatively charged pollutants and the flat membrane, reducing the chance of pollutants depositing on the membrane and preventing pollutants from entering the pores of the flat membrane. This helps to maintain the openness and permeability of the membrane pore channels and reduce fouling on the flat membrane. DETAILED DESCRIPTION

[0048] In order to better explain the present invention and facilitate understanding, the present invention is described in detail below in conjunction with specific implementation methods.

[0049] The present invention provides a treatment system for preparing drinking water, comprising a water inlet device, a filter device and an immersed flat membrane filtration device arranged in sequence. The immersed flat membrane filtration device comprises a membrane stack, the membrane stack comprises a plurality of membrane bag units, and the membrane bag unit comprises a flat membrane.

[0050] In the present invention, the raw material for preparing the flat membrane is a polymer doped with a negatively charged microporous framework material. The raw material for preparing the negatively charged microporous framework material includes 4,6-dicyanoresorcinol, 1,4-butane sultone, and potassium salt.

[0051] The present invention adopts a polymer doped with a negatively charged microporous framework material as a raw material for preparing a flat membrane. The negatively charged microporous framework material has a rigid microporous structure, which can increase the water permeation channel in the flat membrane and can also form a through structure with the membrane pores in the flat membrane, effectively shortening the water transmission path, improving the membrane flux, and thus improving the water treatment efficiency.

[0052] In addition to improving membrane flux, negatively charged microporous frame materials also have negative charge. Many organic matter, colloidal particles and microorganisms in the water also have negative charges on their surfaces. When approaching a flat membrane that is also negatively charged, electrostatic repulsion will be generated between the negatively charged pollutants and the flat membrane, reducing the chance of pollutants depositing on the membrane and preventing pollutants from entering the pores of the flat membrane. This helps to maintain the openness and permeability of the membrane pore channels and reduce fouling on the flat membrane.

[0053] Preferably, in the present invention, the method for preparing the negatively charged microporous framework material comprises the following steps:

[0054] S1: Add 4,6-dicyanoresorcinol, 1,4-butane sultone and potassium salt to a first organic solvent, and react at 110-130°C for 10-15h to obtain potassium 4,4'-(4,6-dicyano-1,3-diphenoxy)dibutanesulfonate. The potassium salt may be potassium carbonate, the first organic solvent may be N,N-dimethylacetamide, and the molar ratio of 4,6-dicyanoresorcinol, 1,4-butane sultone and potassium salt is 1:(2.2-2.5):(2.5-3.5).

[0055] S2: Add potassium 4,4'-(4,6-dicyano-1,3-diphenyloxy)dibutanesulfonate and 4,6-dicyanoresorcinol to a second organic solvent, and react at 60-80°C for 5-7h to obtain a negatively charged microporous framework material. In this step, the molar ratio of potassium 4,4'-(4,6-dicyano-1,3-diphenyloxy)dibutanesulfonate to 4,6-dicyanoresorcinol is 1:2-1:3, and the second organic solvent is preferably trifluoromethanesulfonic acid.

[0056] The structural formula of the above 4,6-dicyanoresorcinol is as follows:

[0057] ;

[0058] The raw material polymer for preparing the flat membrane can be one of polyethylene, polypropylene, polysulfone, polyethersulfone and polyvinylidene fluoride, or a mixture of several of them. The negatively charged microporous framework material accounts for 0.5-25% of the polymer mass.

[0059] Preferably, in addition to the flat membranes, the membrane bag unit of the present invention further comprises a liner spacer disposed between the flat membranes, which may specifically be a polyvinyl chloride spacer or a polypropylene spacer.

[0060] The surface of the lining separator can be coated with a hydrophilic polymer containing nano-catalytic material, wherein the nano-catalytic material accounts for 0.05-8% of the mass of the hydrophilic polymer, and the hydrophilic polymer can be one of polyvinyl pyrrolidone, polyacrylic acid and polyacrylamide, or a mixture of several of them.

[0061] The hydrophilic polymer coated on the surface of the lining mesh can improve the anti-fouling performance of the lining mesh, inhibit the attachment of pollutants during long-term use, and prevent the accumulation of pollutants on the lining mesh during operation of the submerged flat membrane filtration device, causing blockage of the water flow channel and reduction of water flux.

[0062] Specifically, the preparation method of the nano-catalytic material coated on the surface of the lining separator is as follows:

[0063] After the cobalt salt and the iron salt are hydrothermally reacted at a pH of 8-9 and a temperature of 120-150° C. for 20-30 hours, graphene oxide is added and the reaction is continued for 2-4 hours to obtain a layered metal-graphene oxide nanocatalytic material.

[0064] The molar ratio of cobalt salt to iron salt is 1:1-1:1.5, the cobalt salt can be cobalt nitrate, cobalt chloride, cobalt sulfate and crystalline hydrates thereof, the iron salt can be ferric nitrate, ferric chloride, ferric sulfate and crystalline hydrates thereof, and the mass of graphene oxide is 5-10% of the sum of the masses of the cobalt salt and the iron salt.

[0065] This nanocatalytic material can cause micro-pollutants that are difficult to remove in water to undergo nano-confined catalytic reactions, further improving the water quality of the submerged flat membrane filtration device. At the same time, graphene oxide can also serve as an electron transfer medium to promote the reduction and regeneration of cobalt and iron, effectively improving the stability of the nanocatalytic material's performance in oxidizing micro-pollutants.

[0066] Preferably, the porosity of the flat membrane is 40-80%, and the two adjacent flat membranes in the present invention are respectively recorded as flat membrane A and flat membrane B, the composite photocatalyst is coated on the flat membrane A, and the composite adsorption material is coated on the flat membrane B. Further preferably, the submerged flat membrane filtration device is immersed in the water body during operation, and in the membrane bag unit, the flat membrane A and the flat membrane B are respectively coated with the above-mentioned composite photocatalyst and composite adsorption material on the side facing outward, that is, toward the water body.

[0067] The preparation method of the above composite photocatalyst is as follows:

[0068] At 20-30° C., 3,5-dicyclopentyltriazole, aminophthalide and silver nitrate are reacted in a third organic solvent for 48-72 hours to obtain a silver-triazole-aminophthalide complex, and then the silver-triazole-aminophthalide complex is mixed with titanate to obtain a composite photocatalyst, in which the mass proportion of the silver-triazole-aminophthalide complex is higher than that of titanate, the silver-triazole-aminophthalide complex is the main component, and the titanate is the auxiliary component.

[0069] The structural formula of 3,5-dicyclopentyltriazole is as follows:

[0070] ;

[0071] Preferably, the molar ratio of 3,5-dicyclopentyltriazole, aminophthalide and silver nitrate is (0.8-1.2):(1-1.4):(0.8-1.2), the third organic solvent is a mixed solution of acetonitrile and ethanol, wherein the volume ratio of acetonitrile to ethanol is 1:1, and the titanate is magnesium titanate or barium titanate. The aminophthalide may be 5-aminophthalide or 6-aminophthalide.

[0072] The composite photocatalyst coated on the flat membrane A can photocatalytically degrade pollutants in the water, and can efficiently remove impurities while filtering the water body, which can not only improve the quality of water production, but also inhibit the enrichment of pollutants on the membrane surface. Specifically, the optical band gap of the triazole unit containing an imine bond in the silver-triazole-aminophthalide complex is narrow, which can reduce the charge transfer potential well and enhance the charge transfer and separation efficiency during the photocatalytic reaction. In the silver-triazole-aminophthalide complex, the conjugated structure formed by aminophthalide and triazole has light absorption characteristics, which can broaden the light absorption range and synergistically improve the performance of photocatalytic degradation of pollutants. The silver-triazole-aminophthalide complex can also effectively fix silver salts through π complexation, thereby promoting the adsorption of pollutants by the complex, thereby achieving the dual effects of catalysis + adsorption of pollutants in water.

[0073] Furthermore, the titanate mixed in the composite photocatalyst can provide self-aggregation sites, allowing pollutants or flocculants to self-aggregate on the membrane surface, further improving the filtration effect of the submerged flat membrane filtration device on the water body.

[0074] The composite photocatalyst can be coated on the flat film A as follows:

[0075] The flat film A is heated to 100-120° C., and then the composite photocatalyst is sprayed on the surface of the flat film. The purpose of heating is to make the composite photocatalyst better bonded to the surface of the flat film.

[0076] Preferably, the preparation method of the above composite adsorbent material is as follows:

[0077] Acetate and hydroxyterephthalic acid are added to the fourth solvent, reacted at a temperature of 120-160°C for 16-20 hours to obtain an intermediate product, then the intermediate product is added to pyridine at 70-90°C, and then tetraethynylpyrene is added, reacted for 1.5-2.5 hours to obtain a porous adsorption material with polyalkynylpyrene on the surface, and the porous adsorption material is mixed with titanate to obtain a composite adsorption material, in which the mass proportion of the porous adsorption material is higher than that of titanate, the porous adsorption material is the main component, and the titanate is the auxiliary component. Among them, the mass ratio of tetraethynylpyrene to the intermediate product is 1:2-1:3, and the concentration of tetraethynylpyrene in pyridine is 2-5mmol / L. Tetraethynylpyrene can specifically be 1,3,6,8-tetraethynylpyrene.

[0078] Preferably, the acetate may be zinc acetate or zirconium acetate, the molar ratio of acetate to hydroxyterephthalic acid is 2:1-3:1, the fourth solvent may be N,N-dimethylformamide, and the titanate may be magnesium titanate or barium titanate. Further preferably, the hydroxyterephthalic acid in the present invention may be 2-hydroxyterephthalic acid.

[0079] The composite adsorbent material coated on the surface of the flat membrane B has abundant adsorption channels and interlayer pores, which can efficiently adsorb impurity ions in the water body and further purify the water quality. In addition, the repulsive effect of polyacetylenic pyrene on the surface of the composite adsorbent material can block large molecular pollutants or flocculants from entering the porous structure, avoid clogging of the porous framework in the composite adsorbent material, and make the composite adsorbent material have a more stable adsorption effect. Similarly, the titanate mixed in the composite adsorbent material can also provide self-coagulation sites, so that pollutants or flocculants self-aggregate on the membrane surface, further improving the filtration effect of the submerged flat membrane filtration device on the water body.

[0080] Further preferably, in addition to the water inlet device, the filter device and the submerged flat membrane filtration device, the treatment system of the present invention also includes a water production device and a sewage discharge device, the water production device can be a water production chamber connected to the water outlet of the submerged flat membrane filtration device, and the sewage discharge device can be connected to the mud collection area at the bottom of the submerged flat membrane filtration device. The submerged flat membrane filtration device also includes a clamping plate for fixing the membrane stack.

[0081] In order to further clarify the scheme of the present invention and its technical advancement, the following is a description in conjunction with specific embodiments and technical effects.

[0082] Example 1

[0083] This embodiment provides a treatment system for preparing drinking water, including a water inlet device, a filter device, an immersed flat membrane filter device, a water production device, and a sewage discharge device arranged in sequence. The immersed flat membrane filter device includes a clamping plate and a membrane stack, the membrane stack includes a plurality of membrane bag units, the membrane bag unit includes a flat membrane and a polyvinyl chloride lining spacer arranged between the flat membranes, and the flat membranes on both sides of the lining spacer are respectively recorded as flat membrane A and flat membrane B.

[0084] Flat membrane A and flat membrane B both use polyethylene containing negatively charged microporous framework materials, wherein the proportion of negatively charged microporous framework materials is 1wt%, and the porosity of flat membrane A and flat membrane B is 40%. After flat membrane A is heated at 100°C, a composite photocatalyst is sprayed on the surface, and a composite adsorption material is coated on the surface of flat membrane B, and polyvinyl pyrrolidone containing nanocatalytic materials is coated on the surface of the inner lining mesh, wherein the nanocatalytic materials account for 0.1wt% of the hydrophilic polymer. The surfaces of the coated materials of flat membrane A and flat membrane B are both facing the water body.

[0085] In this embodiment, the preparation method of the negatively charged microporous framework material is as follows:

[0086] S1: 4,6-dicyanoresorcinol, 1,4-butane sultone and potassium carbonate were added to N,N-dimethylacetamide at a molar ratio of 1:2.3:3, and reacted at 120° C. for 10 h to obtain potassium 4,4'-(4,6-dicyano-1,3-diphenoxy)dibutanesulfonate.

[0087] S2: Potassium 4,4'-(4,6-dicyano-1,3-diphenyloxy)dibutanesulfonate and 4,6-dicyanoresorcinol were added to trifluoromethanesulfonic acid at a molar ratio of 1:2, and reacted at 60°C for 6 hours. After the reaction, the system was washed to obtain a negatively charged microporous framework material.

[0088] In this embodiment, the preparation method of the composite photocatalyst includes: reacting 3,5-dicyclopentyltriazole, 5-aminophthalide and silver nitrate in a mixed solution of acetonitrile and ethanol in a volume ratio of 1:1 at 25°C for 48 hours in a molar ratio of 1:1.2:1 to obtain a silver-triazole-5-aminophthalide complex, and then mixing the silver-triazole-5-aminophthalide complex with magnesium titanate to obtain a composite photocatalyst.

[0089] In this embodiment, the preparation method of the composite adsorbent material includes: adding zinc acetate and 2-hydroxyterephthalic acid to N,N-dimethylformamide at a molar ratio of 2:1, reacting at a temperature of 140°C for 18 hours to obtain an intermediate product, adding the intermediate product to pyridine, and then adding 1,3,6,8-tetraethynylpyrene, reacting at 80°C for 2 hours to obtain a porous adsorbent material, the mass ratio of 1,3,6,8-tetraethynylpyrene to the intermediate product is 1:2.5, and the concentration of 1,3,6,8-tetraethynylpyrene in pyridine is 3mmol / L. The porous adsorbent material is mixed with magnesium titanate to obtain a composite adsorbent material.

[0090] The preparation method of the nanocatalytic material is as follows: after hydrothermal reaction of cobalt nitrate and ferric nitrate in a molar ratio of 1:1 at pH 8 and temperature 120°C for 24 hours, graphene oxide with a total weight of 5% of iron salt and cobalt salt is added, and the reaction is continued with stirring for 3 hours. After filtering and drying, a layered metal-graphene oxide nanocatalytic material is obtained.

[0091] The membrane flux of the submerged flat membrane filtration device of this embodiment was measured to be 187LMH. The raw water with a COD of 150.7 mg / L and an iron content of 45.8 mg / L was provided. After being treated by the submerged flat membrane filtration device of this embodiment, the COD of the produced water was 7.4 mg / L and the iron content was 0.08 mg / L. No fouling or blockage occurred during the entire water production process, and there was no obvious change in the membrane flux before and after filtration.

[0092] Example 2

[0093] This embodiment provides a treatment system for preparing drinking water, including a water inlet device, a filter device, an immersed flat membrane filter device, a water production device, and a sewage discharge device arranged in sequence. The immersed flat membrane filter device includes a clamping plate and a membrane stack, the membrane stack includes a plurality of membrane bag units, the membrane bag unit includes a flat membrane and a polypropylene liner spacer arranged between the flat membranes, and the flat membranes on both sides of the liner spacer are respectively recorded as flat membrane A and flat membrane B.

[0094] Both flat membrane A and flat membrane B use polypropylene containing negatively charged microporous framework materials, wherein the proportion of negatively charged microporous framework materials is 10wt%, and the porosity of flat membrane A and flat membrane B is 60%. After flat membrane A is heated at 120°C, a composite photocatalyst is sprayed on the surface, and the surface of flat membrane B is coated with a composite adsorption material, and the surface of the inner lining is coated with polyacrylic acid containing nanocatalytic materials, wherein the nanocatalytic materials account for 2.5wt% of the hydrophilic polymer. The surfaces of the coated materials of flat membrane A and flat membrane B are both facing the water body.

[0095] In this embodiment, the preparation method of the negatively charged microporous framework material is as follows:

[0096] S1: 4,6-dicyanoresorcinol, 1,4-butane sultone and potassium carbonate were added to N,N-dimethylacetamide at a molar ratio of 1:2.2:2.5, and reacted at 130° C. for 12 h to obtain potassium 4,4'-(4,6-dicyano-1,3-diphenoxy)dibutanesulfonate.

[0097] S2: Potassium 4,4'-(4,6-dicyano-1,3-diphenyloxy)dibutanesulfonate and 4,6-dicyanoresorcinol were added to trifluoromethanesulfonic acid at a molar ratio of 1:3, and reacted at 70°C for 5 hours. After the reaction, the system was washed to obtain a negatively charged microporous framework material.

[0098] In this embodiment, the preparation method of the composite photocatalyst includes: reacting 3,5-dicyclopentyltriazole, 6-aminophthalide and silver nitrate in a mixed solution of acetonitrile and ethanol in a volume ratio of 1:1 at 20°C for 48 hours in a molar ratio of 0.8:1:0.8 to obtain a silver-triazole-5-aminophthalide complex, and then mixing the silver-triazole-6-aminophthalide complex with barium titanate to obtain a composite photocatalyst.

[0099] In this embodiment, the preparation method of the composite adsorbent material includes: adding zinc acetate and 2-hydroxyterephthalic acid to N,N-dimethylformamide at a molar ratio of 2.5:1, reacting at a temperature of 120°C for 20 hours to obtain an intermediate product, adding the intermediate product to pyridine, and then adding 1,3,6,8-tetraethynylpyrene, reacting at 70°C for 2.5 hours to obtain a porous adsorbent material, the mass ratio of 1,3,6,8-tetraethynylpyrene to the intermediate product is 1:2, and the concentration of 1,3,6,8-tetraethynylpyrene in pyridine is 5mmol / L. The porous adsorbent material is mixed with barium titanate to obtain a composite adsorbent material.

[0100] The preparation method of the nanocatalytic material is as follows: after hydrothermal reaction of cobalt chloride and ferric chloride in a molar ratio of 1:1.5 at pH 8 and temperature 150°C for 20 hours, graphene oxide with a total weight of 8% of iron salt and cobalt salt is added, and the reaction is continued with stirring for 2 hours. After filtering and drying, a layered metal-graphene oxide nanocatalytic material is obtained.

[0101] The membrane flux of the submerged flat membrane filtration device of this embodiment was measured to be 192LMH. The raw water with a COD of 150.7 mg / L and an iron content of 45.8 mg / L was provided. After being treated by the submerged flat membrane filtration device of this embodiment, the COD of the produced water was 6.3 mg / L and the iron content was 0.06 mg / L. No fouling or blockage occurred during the entire water production process, and there was no obvious change in the membrane flux before and after filtration.

[0102] Example 3

[0103] This embodiment provides a treatment system for preparing drinking water, including a water inlet device, a filter device, an immersed flat membrane filter device, a water production device, and a sewage discharge device arranged in sequence. The immersed flat membrane filter device includes a clamping plate and a membrane stack, the membrane stack includes a plurality of membrane bag units, the membrane bag unit includes a flat membrane and a polyvinyl chloride lining spacer arranged between the flat membranes, and the flat membranes on both sides of the lining spacer are respectively recorded as flat membrane A and flat membrane B.

[0104] Both flat membrane A and flat membrane B use polysulfone containing negatively charged microporous framework materials, wherein the proportion of negatively charged microporous framework materials is 20wt%, and the porosity of flat membrane A and flat membrane B is 80%. After flat membrane A is heated at 110°C, a composite photocatalyst is sprayed on the surface, the surface of flat membrane B is coated with a composite adsorption material, and the surface of the inner lining is coated with polyvinyl pyrrolidone and polyacrylic acid containing nanocatalytic materials, wherein the nanocatalytic material accounts for 5wt% of the hydrophilic polymer. The surfaces of the coated materials of flat membrane A and flat membrane B are both facing the water body.

[0105] In this embodiment, the preparation method of the negatively charged microporous framework material is as follows:

[0106] S1: 4,6-dicyanoresorcinol, 1,4-butane sultone and potassium carbonate were added to N,N-dimethylacetamide at a molar ratio of 1:2.5:3.5, and reacted at 110° C. for 15 h to obtain potassium 4,4'-(4,6-dicyano-1,3-diphenoxy)dibutanesulfonate.

[0107] S2: Potassium 4,4'-(4,6-dicyano-1,3-diphenyloxy)dibutanesulfonate and 4,6-dicyanoresorcinol were added to trifluoromethanesulfonic acid at a molar ratio of 1:2.5, and reacted at 80°C for 7 hours. After the reaction, the system was washed to obtain a negatively charged microporous framework material.

[0108] In this embodiment, the preparation method of the composite photocatalyst includes: reacting 3,5-dicyclopentyltriazole, 5-aminophthalide and silver nitrate in a mixed solution of acetonitrile and ethanol in a volume ratio of 1:1 at 30°C for 72 hours in a molar ratio of 1.2:1.4:1.2 to obtain a silver-triazole-5-aminophthalide complex, and then mixing the silver-triazole-5-aminophthalide complex with magnesium titanate to obtain a composite photocatalyst.

[0109] In this embodiment, the preparation method of the composite adsorbent material includes: adding zirconium acetate and 2-hydroxyterephthalic acid to N,N-dimethylformamide at a molar ratio of 3:1, reacting at a temperature of 120°C for 16 hours to obtain an intermediate product, adding the intermediate product to pyridine, and then adding 1,3,6,8-tetraethynylpyrene, reacting at 90°C for 1.5 hours to obtain a porous adsorbent material, the mass ratio of 1,3,6,8-tetraethynylpyrene to the intermediate product is 1:3, and the concentration of 1,3,6,8-tetraethynylpyrene in pyridine is 2mmol / L. The porous adsorbent material is mixed with magnesium titanate to obtain a composite adsorbent material.

[0110] The preparation method of the nanocatalytic material is as follows: after hydrothermal reaction of cobalt sulfate and iron sulfate in a molar ratio of 1:1.2 at pH 9 and temperature 135°C for 30 hours, graphene oxide accounting for 10% of the total mass of iron salt and cobalt salt is added, and the stirring reaction is continued for 4 hours. After filtering and drying, a layered metal-graphene oxide nanocatalytic material is obtained.

[0111] The membrane flux of the submerged flat membrane filtration device of this embodiment was measured to be 195LMH. The raw water with a COD of 150.7 mg / L and an iron content of 45.8 mg / L was provided. After being treated by the submerged flat membrane filtration device of this embodiment, the COD of the produced water was 7.0 mg / L and the iron content was 0.09 mg / L. No fouling or blockage occurred during the entire water production process, and there was no obvious change in the membrane flux before and after filtration.

[0112] Example 4

[0113] This embodiment provides a treatment system for preparing drinking water, including a water inlet device, a filter device, an immersed flat membrane filter device, a water production device, and a sewage discharge device arranged in sequence. The immersed flat membrane filter device includes a clamping plate and a membrane stack, the membrane stack includes a plurality of membrane bag units, the membrane bag unit includes a flat membrane and a polypropylene liner spacer arranged between the flat membranes, and the flat membranes on both sides of the liner spacer are respectively recorded as flat membrane A and flat membrane B.

[0114] Flat membrane A and flat membrane B both use a mixture of polyethylene and polypropylene containing negatively charged microporous framework materials, wherein the proportion of negatively charged microporous framework materials is 15wt%, and the porosity of flat membrane A and flat membrane B is 70%. Flat membrane A is heated to 120°C, and a composite photocatalyst is sprayed on the surface, the surface of flat membrane B is coated with a composite adsorption material, and the surface of the inner lining is coated with polyacrylamide containing nanocatalytic materials, wherein the nanocatalytic materials account for 2.5wt% of the hydrophilic polymer. The surfaces of the coated materials of flat membrane A and flat membrane B are both facing the water body.

[0115] In this embodiment, the preparation method of the negatively charged microporous framework material is as follows:

[0116] S1: 4,6-dicyanoresorcinol, 1,4-butane sultone and potassium carbonate were added to N,N-dimethylacetamide at a molar ratio of 1:2.4:3.2, and reacted at 130° C. for 12 h to obtain potassium 4,4'-(4,6-dicyano-1,3-diphenoxy)dibutanesulfonate.

[0117] S2: Potassium 4,4'-(4,6-dicyano-1,3-diphenyloxy)dibutanesulfonate and 4,6-dicyanoresorcinol were added to trifluoromethanesulfonic acid at a molar ratio of 1:3, and reacted at 70°C for 6 hours. After the reaction, the system was washed to obtain a negatively charged microporous framework material.

[0118] In this embodiment, the preparation method of the composite photocatalyst includes: reacting 3,5-dicyclopentyltriazole, 6-aminophthalide and silver nitrate in a mixed solution of acetonitrile and ethanol in a volume ratio of 1:1 at 22°C for 60 hours in a molar ratio of 1:1.2:1 to obtain a silver-triazole-5-aminophthalide complex, and then mixing the silver-triazole-6-aminophthalide complex with barium titanate to obtain a composite photocatalyst.

[0119] In this embodiment, the preparation method of the composite adsorbent material includes: adding zinc acetate and 2-hydroxyterephthalic acid to N,N-dimethylformamide at a molar ratio of 2:1, reacting at a temperature of 160°C for 20 hours to obtain an intermediate product, adding the intermediate product to pyridine, and then adding 1,3,6,8-tetraethynylpyrene, reacting at 80°C for 2 hours to obtain a porous adsorbent material, the mass ratio of 1,3,6,8-tetraethynylpyrene to the intermediate product is 1:2.2, and the concentration of 1,3,6,8-tetraethynylpyrene in pyridine is 4mmol / L. The porous adsorbent material is mixed with barium titanate to obtain a composite adsorbent material.

[0120] The preparation method of the nanocatalytic material is as follows: after hydrothermal reaction of cobalt chloride hexahydrate and ferric sulfate hexahydrate in a molar ratio of 1:1.5 at pH 8.5 and temperature 150°C for 24 hours, graphene oxide with a total weight of 8% of iron salt and cobalt salt is added, and the reaction is continued with stirring for 3 hours. After filtering and drying, a layered metal-graphene oxide nanocatalytic material is obtained.

[0121] The membrane flux of the submerged flat membrane filtration device of this embodiment was measured to be 190LMH. The raw water with a COD of 150.7 mg / L and an iron content of 45.8 mg / L was provided. After being treated by the submerged flat membrane filtration device of this embodiment, the COD of the produced water was 7.3 mg / L and the iron content was 0.07 mg / L. No fouling or blockage occurred during the entire water production process, and there was no obvious change in the membrane flux before and after filtration.

[0122] Example 5

[0123] This embodiment provides a treatment system for preparing drinking water. The difference from Embodiment 1 is that both flat membrane A and flat membrane B use polyethersulfone containing negatively charged microporous framework material, and the blending ratio of the negatively charged microporous framework material in the polymer is 0.5wt%.

[0124] The membrane flux of the submerged flat membrane filtration device of this embodiment was measured to be 173LMH. The raw water with a COD of 150.7 mg / L and an iron content of 45.8 mg / L was provided. After being treated by the submerged flat membrane filtration device of this embodiment, the COD of the produced water was 9.8 mg / L and the iron content was 0.14 mg / L. No fouling or blockage occurred during the entire water production process, and there was no obvious change in the membrane flux before and after filtration.

[0125] Example 6

[0126] This embodiment provides a treatment system for preparing drinking water. The difference from Embodiment 1 is that both flat membrane A and flat membrane B use polyvinylidene fluoride containing negatively charged microporous framework material, and the blending ratio of the negatively charged microporous framework material in the polymer is 25wt%.

[0127] The membrane flux of the submerged flat membrane filtration device of this embodiment was measured to be 182LMH. The raw water with a COD of 150.7 mg / L and an iron content of 45.8 mg / L was provided. After being treated by the submerged flat membrane filtration device of this embodiment, the COD of the produced water was 8.4 mg / L and the iron content was 0.17 mg / L. No fouling or blockage occurred during the entire water production process, and there was no obvious change in the membrane flux before and after filtration.

[0128] Example 7

[0129] This embodiment provides a treatment system for preparing drinking water, which differs from Embodiment 1 in that the nanocatalytic material accounts for 0.05 wt % of the hydrophilic polymer.

[0130] The membrane flux of the submerged flat membrane filtration device of this embodiment was measured to be 186LMH. The raw water with a COD of 150.7 mg / L and an iron content of 45.8 mg / L was provided. After being treated by the submerged flat membrane filtration device of this embodiment, the COD of the produced water was 9.5 mg / L and the iron content was 0.15 mg / L. No fouling or blockage occurred during the entire water production process, and there was no obvious change in the membrane flux before and after filtration.

[0131] Example 8

[0132] This embodiment provides a treatment system for preparing drinking water, which differs from Embodiment 1 in that the nanocatalytic material accounts for 8 wt % of the hydrophilic polymer.

[0133] The membrane flux of the submerged flat membrane filtration device of this embodiment was measured to be 187LMH. The raw water with a COD of 150.7 mg / L and an iron content of 45.8 mg / L was provided. After being treated by the submerged flat membrane filtration device of this embodiment, the COD of the produced water was 8.9 mg / L and the iron content was 0.13 mg / L. No fouling or blockage occurred during the entire water production process, and there was no obvious change in the membrane flux before and after filtration.

[0134] Comparative Example 1

[0135] This comparative example provides a treatment system for preparing drinking water, which is different from Example 1 in that the blending ratio of the negatively charged microporous framework material in the raw polymer for preparing the flat membrane A and the flat membrane B is 0%.

[0136] The membrane flux of the submerged flat membrane filtration device in this comparative example was measured to be 128LMH. The raw water with a COD of 150.7 mg / L and an iron content of 45.8 mg / L was provided. After being treated by the submerged flat membrane filtration device in this comparative example, the COD of the produced water was 15.4 mg / L and the iron content was 0.23 mg / L. In this comparative example, the membrane flux of the submerged flat membrane filtration device was significantly decreased compared with Examples 1-8, and the system processing was unstable, and fouling would occur after long-term operation.

[0137] Comparative Example 2

[0138] This comparative example provides a treatment system for preparing drinking water, which differs from Example 1 in that the surface of the flat membrane A is not sprayed with a composite photocatalyst.

[0139] The membrane flux of the submerged flat membrane filtration device in this comparative example was measured to be 183LMH. The raw water with a COD of 150.7 mg / L and an iron content of 45.8 mg / L was provided. After being treated by the submerged flat membrane filtration device in this comparative example, the COD of the produced water was 63.5 mg / L and the iron content was 2.7 mg / L. In this comparative example, the pollutant removal effect of the submerged flat membrane filtration device was significantly worse than that of Examples 1-8, and the system processing was unstable, and fouling would occur after long-term operation.

[0140] Comparative Example 3

[0141] This comparative example provides a treatment system for preparing drinking water, which differs from Example 1 in that the surface of the flat membrane B is not coated with a composite adsorption material.

[0142] The membrane flux of the submerged flat membrane filtration device in this comparative example was measured to be 178LMH. The raw water with a COD of 150.7 mg / L and an iron content of 45.8 mg / L was provided. After being treated by the submerged flat membrane filtration device in this comparative example, the COD of the produced water was 50.4 mg / L and the iron content was 6.9 mg / L. In this comparative example, the pollutant removal effect of the submerged flat membrane filtration device was significantly worse than that of Examples 1-8, and the system processing was unstable, and fouling would occur after long-term operation.

[0143] Comparative Example 4

[0144] This comparative example provides a treatment system for preparing drinking water, which differs from Example 1 in that the surface of the lining screen is not coated with a hydrophilic polymer containing nano-catalytic material.

[0145] The membrane flux of the submerged flat membrane filtration device in this comparative example was measured to be 184LMH. The raw water with a COD of 150.7 mg / L and an iron content of 45.8 mg / L was provided. After being treated by the submerged flat membrane filtration device in this comparative example, the COD of the produced water was 27.2 mg / L and the iron content was 0.87 mg / L. In this comparative example, the pollutant removal effect of the submerged flat membrane filtration device was significantly worse than that of Examples 1-8, and the system processing was unstable, and fouling would occur after long-term operation.

[0146] In addition, it has been verified that under the conditions of the same raw water quality, the same inlet water temperature, the same inlet water flow rate, and the same inlet water pressure, when the submerged flat membrane filtration device of Example 2 is blocked by dirt, the submerged flat membrane filtration device of Example 3 can still continue to operate stably for 2 days, the submerged flat membrane filtration device of Example 4 can continue to operate stably for 4 days, the submerged flat membrane filtration device of Example 1 can continue to operate stably for 10 days, and the submerged flat membrane filtration devices of Examples 1-8 can all continue to operate stably for more than 35 days, among which the submerged flat membrane filtration devices of Examples 1-4 can continue to operate stably for more than 40 days.

[0147] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements 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 treatment system for preparing drinking water, comprising a water inlet device, a filter device and an immersed flat membrane filter device arranged in sequence; characterized in that: The submerged flat membrane filtration device comprises a membrane stack, wherein the membrane stack comprises a plurality of membrane bag units, and the membrane bag units comprise flat membranes; The raw material for preparing the flat membrane is a polymer doped with a negatively charged microporous framework material; The raw materials for preparing the negatively charged microporous framework material include 4,6-dicyanoresorcinol, 1,4-butane sultone, and potassium salt.

2. The treatment system for preparing drinking water according to claim 1, characterized in that: The preparation method of the negatively charged microporous framework material comprises the following steps: S1: reacting 4,6-dicyanoresorcinol, 1,4-butane sultone and potassium salt at 110-130° C. for 10-15 h to obtain potassium 4,4′-(4,6-dicyano-1,3-diphenoxy)dibutanesulfonate; S2: Potassium 4,4'-(4,6-dicyano-1,3-diphenoxy)dibutanesulfonate is reacted with 4,6-dicyanoresorcinol at 60-80° C. for 5-7 hours to obtain a negatively charged microporous framework material.

3. The treatment system for preparing drinking water according to claim 2, characterized in that: In step S1, 4,6-dicyanoresorcinol, 1,4-butane sultone and potassium salt are added to a first organic solvent, and reacted at 110-130° C. for 10-15 hours to obtain potassium 4,4'-(4,6-dicyano-1,3-diphenoxy)dibutanesulfonate; the potassium salt is potassium carbonate, the first organic solvent is N,N-dimethylacetamide, and the molar ratio of 4,6-dicyanoresorcinol, 1,4-butane sultone and potassium salt is 1:(2.2-2.5):(2.5-3.5); In step S2, potassium 4,4'-(4,6-dicyano-1,3-diphenyloxy)dibutanesulfonate and 4,6-dicyanoresorcinol are added to a second organic solvent and reacted at 60-80° C. for 5-7 hours to obtain a negatively charged microporous framework material; the molar ratio of potassium 4,4'-(4,6-dicyano-1,3-diphenyloxy)dibutanesulfonate to 4,6-dicyanoresorcinol is 1:2-1:3, and the second organic solvent is trifluoromethanesulfonic acid; The polymer is one or a mixture of polyethylene, polypropylene, polysulfone, polyethersulfone and polyvinylidene fluoride; The negatively charged microporous framework material accounts for 0.5-25% of the mass of the polymer.

4. The treatment system for preparing drinking water according to claim 1, characterized in that: The membrane bag unit also includes an inner lining mesh arranged between the flat membranes; the inner lining mesh is a polyvinyl chloride mesh or a polypropylene mesh; The surface of the inner lining separator is coated with a hydrophilic polymer containing a nano-catalytic material; the nano-catalytic material accounts for 0.05-8% of the mass of the hydrophilic polymer; The hydrophilic polymer is one or a mixture of polyvinyl pyrrolidone, polyacrylic acid and polyacrylamide.

5. The treatment system for preparing drinking water according to claim 4, characterized in that: The preparation method of the nano catalytic material is as follows: The cobalt salt and the iron salt are subjected to a hydrothermal reaction at a pH of 8-9 and a temperature of 120-150° C. for 20-30 hours, and then graphene oxide is added and the reaction is continued for 2-4 hours to obtain a nanocatalytic material; The molar ratio of cobalt salt to iron salt is 1:1-1:1.5; The cobalt salt is one of cobalt nitrate, cobalt chloride, cobalt sulfate and their crystalline hydrates, and the iron salt is one of iron nitrate, iron chloride, iron sulfate and their crystalline hydrates; The mass of graphene oxide is 5-10% of the sum of the mass of cobalt salt and iron salt.

6. The treatment system for preparing drinking water according to claim 1, characterized in that: The porosity of the flat membrane is 40-80%, and two adjacent flat membranes are coated with a composite photocatalyst and a composite adsorption material respectively; The preparation method of the composite photocatalyst is as follows: At 20-30° C., 3,5-dicyclopentyltriazole, aminophthalide and silver nitrate are reacted in a third organic solvent for 48-72 hours to obtain a silver-triazole-aminophthalide complex, and then the silver-triazole-aminophthalide complex is mixed with titanate to obtain a composite photocatalyst.

7. The treatment system for preparing drinking water according to claim 6, characterized in that: The molar ratio of 3,5-dicyclopentyltriazole, aminophthalide and silver nitrate is (0.8-1.2):(1-1.4):(0.8-1.2); The third organic solvent is a mixed solution of acetonitrile and ethanol, wherein the volume ratio of acetonitrile to ethanol is 1:1; The titanate is magnesium titanate or barium titanate.

8. The treatment system for preparing drinking water according to claim 6, characterized in that: The preparation method of the composite adsorption material is as follows: Adding acetate and hydroxyterephthalic acid into a fourth solvent, reacting at a temperature of 120-160° C. for 16-20 hours to obtain an intermediate product; At 70-90° C., adding the intermediate product to pyridine, and then adding tetraethynylpyrene, reacting for 1.5-2.5 hours to obtain a porous adsorption material, and mixing the porous adsorption material with titanate to obtain a composite adsorption material; The mass ratio of tetraethynylpyrene to the intermediate product is 1:2-1:3, and the concentration of tetraethynylpyrene in pyridine is 2-5 mmol / L.

9. The treatment system for preparing drinking water according to claim 8, characterized in that: The acetate is zinc acetate or zirconium acetate, the molar ratio of acetate to hydroxyterephthalic acid is 2:1-3:1, the fourth solvent is N,N-dimethylformamide, and the titanate is magnesium titanate or barium titanate.

10. The treatment system for preparing drinking water according to claim 1, characterized in that: The treatment system also includes a water production device and a sewage discharge device; The submerged flat membrane filtration device also includes a clamping plate for fixing the membrane stack.