Composite filter material for treating organic wastewater

Abstract

The application provides a kind of composite filter material for treating organic wastewater, the composite filter material includes upper filter layer, support layer and lower filter layer, three-layer filter material is made by adhesive or needle punching, the upper filter layer uses electrostatic spinning layer of flocking, the support layer is directional porous cellulose aerogel layer, and the lower filter layer is porous cellulose carbon aerogel layer, wherein the thickness of the upper filter layer is 0.4-0.8cm, the thickness of the support layer is 0.3-0.5cm, and the thickness of the porous cellulose carbon aerogel layer is 0.2-0.3cm.The application provides a kind of composite filter material for treating organic wastewater, uses physical adsorption method, utilizes the structure of composite multilayer, reduces the content of impurities and the like in organic wastewater.

Description

Technical Field

[0001] This invention relates to the field of wastewater filtration materials, and more specifically to a composite filtration material for treating organic wastewater. Background Technology

[0002] In recent years, the development of industries such as papermaking, dyeing, petroleum, and pharmaceuticals has generated a large amount of organic wastewater during product processing. This wastewater, discharged into the environment, not only pollutes the environment but also endangers human health. The organic matter content in industrial organic wastewater is above 2000 mg / L, existing in the form of suspended solids or dissolved substances. The hazards of industrial organic wastewater mainly stem from: the accumulation of large amounts of organic matter, leading to a decrease in oxygen content and affecting the growth and reproduction of aquatic organisms; insufficient oxygen in the water causing organic matter to decompose and produce foul-smelling gases, thus deteriorating water quality; and toxic organic substances such as phenols directly polluting water bodies. Common methods for treating industrial organic wastewater include extraction, electrolysis, adsorption, photochemical coagulation, and biochemical methods. Extraction has the highest treatment efficiency and requires the least investment. It mainly utilizes the different solubilities of solutes in immiscible solvents. Non-polar organic matter in wastewater has a high solubility in the extractant, which is used to extract and treat the non-polar organic matter in the wastewater. Electrolysis decomposes organic matter in wastewater through electrochemical or redox reactions in an electrolytic cell. Photochemical coagulation uses ultraviolet light to polymerize small organic molecules in wastewater, forming large suspended solids, which are then removed in a sedimentation tank. However, this method is only suitable for high-concentration organic wastewater. Biochemical methods utilize the degradation effects of microorganisms to treat organic wastewater; this method is low-cost and produces no secondary pollution. Summary of the Invention

[0003] Technical problem to be solved: The purpose of this invention is to provide a composite filter material for treating organic wastewater, which uses a physical adsorption method and a multi-layered composite structure to reduce the content of impurities in organic wastewater.

[0004] Technical solution: A composite filter material for treating organic wastewater, comprising an upper filter layer, a support layer, and a lower filter layer, bonded together by an adhesive or needle punching to form a three-layer filter material. The upper filter layer is a flocked electrospun layer, the support layer is a directional porous cellulose aerogel layer, and the lower filter layer is a porous cellulose carbon aerogel layer. The thickness of the upper filter layer is 0.4-0.8 cm, the thickness of the support layer is 0.3-0.5 cm, and the thickness of the porous cellulose carbon aerogel layer is 0.2-0.3 cm.

[0005] Preferably, the method for preparing the upper filter layer includes the following steps:

[0006] S1. Add aluminum isopropyl alcohol into water, heat to reflux, then add nitric acid solution, stir to obtain aluminum sol, add PVP alcohol solution into the aluminum sol, and stir to obtain an electrospinning solution;

[0007] S2. Electrospin the electrospinning solution to obtain a white electrospinning membrane;

[0008] S3. Add aluminum chloride and aluminum isopropyl alcohol into a nitric acid solution, heat to reflux, then add aluminum powder to obtain an aluminum sol, add silica sol to the aluminum sol, and age the sol to obtain a spinnable precursor sol, and spin the sol by dry spinning to obtain an alumina gel fiber;

[0009] S4. Use needle punching to plant the alumina gel fiber on the surface of the electrospinning membrane, trim the surface fibers into a wave form, and then sinter to obtain an upper filter layer.

[0010] Preferably, the preparation method of the support layer comprises the following steps:

[0011] S1-1. Add cellulose microcrystals into water to prepare a cellulose solution with a concentration of 2-4 wt%;

[0012] S1-2. Add the cellulose solution into a mold for directional freeze drying at a temperature of -80 to -60 ℃ for 20-40 h to obtain a cellulose aerogel.

[0013] Preferably, the preparation method of the lower filter layer comprises the following steps:

[0014] S2-1. Add cellulose microcrystals into water to prepare a cellulose solution with a concentration of 2-4 wt%;

[0015] S2-2. Add kaolin into the cellulose solution, and stir and ultrasonicize the mixture, then pour the mixture into a mold, and freeze dry at a temperature of -60 to -20 ℃ for 20-40 h to obtain a white mixed aerogel;

[0016] S2-3. Carbonize the white mixed aerogel in a N2 atmosphere, raise the temperature from room temperature to 350 ℃ and maintain for 30 min, continue to raise the temperature to 650-800 ℃ and maintain for 60 min to obtain a carbonized aerogel;

[0017] S2-4. Add the carbonized aerogel into a thionyl chloride solution, wash and vacuum dry, then add into an ethylenediamine solution, stir at 100 ℃ for 10-20 h, cool to room temperature, and wash to remove the ethylenediamine to obtain a porous cellulose carbon aerogel layer.

[0018] Preferably, the molar ratio of aluminum isopropoxide, water and nitric acid in step S1 is 1-2:100-130:0.5-1.

[0019] Preferably, the molar ratio of aluminum chloride, aluminum isopropoxide and aluminum powder in step S3 is 1:1:2, the mass ratio of aluminum sol and silica sol is 10:1-2, and the concentration of the nitric acid solution is 2-4 mol / L.

[0020] Preferably, the pre-needling density in step S4 is 55-70 needles / cm 2 , the main needling density is 65-80 needles / cm 2 , and the sintering temperature is first raised to 550-600 DEG C at a rate of 1 DEG C / min, then raised to 1200-1400 DEG C at a rate of 3-5 DEG C / min, and kept for 2h.

[0021] Beneficial effects: the composite filter material has the following advantages:

[0022] 1. The composite filter material in the application is a 3-layer composite material, the upper filter layer is an electrospun layer with flocking, the support layer is a directional porous cellulose aerogel layer, and the lower filter layer is a porous cellulose carbon aerogel layer, the surface of the electrospun layer with flocking is a wave velvet layer, similar to the structure of a toothbrush, which can filter out suspended solids in sewage first, improving the filtering effect; the pores in the support layer are distributed in a directional and parallel manner, equivalent to a hollow layer, which can buffer the wastewater that has passed through the upper filter layer, adsorb more impurities, and weaken the accumulated impurities on the filtering effect in the later stage; cellulose contains a large amount of hydroxyl groups, which can effectively adsorb part of free metal ions in water; the lower filter layer adopts a porous carbon aerogel, which has a porous structure similar to a sponge, and the wastewater that has been buffered is further filtered through the lower filter layer, using the active groups on the surface of the porous material for secondary adsorption, achieving the effect of further purification.

[0023] 2. The lower filter layer in the application adopts a porous cellulose carbon aerogel layer, which is subjected to amination treatment after carbonization treatment of the cellulose gel, grafts part of amino groups on the surface of the carbon aerogel, and further improves the treatment effect of the wastewater by adding kaolin in the carbon aerogel layer.

[0024] 3. The upper filter layer in the application is a ceramic membrane, the support layer is a cellulose membrane, and the lower filter layer is a carbon aerogel membrane, and the strength gradually weakens along the direction of the wastewater flow, which can prolong the service life of the filter material. DETAILED DESCRIPTION

[0025] The application will be further described below in conjunction with examples, and the following examples are an explanation of the application, but the application is not limited to the following examples:

[0026] Example 1

[0027] A composite filter material for treating organic wastewater includes an upper filter layer, a support layer, and a lower filter layer, which are bonded together by an adhesive or needle punching to form a three-layer filter material. The upper filter layer is a flocked electrospun layer, the support layer is a directional porous cellulose aerogel layer, and the lower filter layer is a porous cellulose carbon aerogel layer. The thickness of the upper filter layer is 0.4 cm, the thickness of the support layer is 0.5 cm, the thickness of the porous cellulose carbon aerogel layer is 0.2 cm, the thickness of the electrospun layer in the upper filter layer is 0.1 cm, and the remainder is flocked.

[0028] The method for preparing the upper filter layer includes the following steps:

[0029] S1. Add aluminum isopropoxide to water, heat and reflux to react, then add nitric acid solution. The molar ratio of aluminum isopropoxide:water:nitric acid is 1:100:0.5. Stir the reaction to obtain aluminum sol. Add PVP alcohol solution to aluminum sol and stir to obtain electrospinning solution.

[0030] S2. Electrospin the spinning solution to obtain a white electrospun film;

[0031] S3. Add aluminum chloride and aluminum isopropoxide to a 2 mol / L nitric acid solution, heat and reflux to react, then add aluminum powder. The molar ratio of aluminum chloride, aluminum isopropoxide and aluminum powder is 0.5:0.5:1.5 to obtain aluminum sol. Add silica sol. The mass ratio of aluminum sol to silica sol is 10:1. Age the sol to obtain a spinnable precursor sol. Dry spin the sol to obtain alumina gel fiber.

[0032] S4. Alumina gel fibers are flocked onto the surface of the electrospun membrane using a needle-punching flocking method. The pre-needling density is 55 needles / cm. 2 The main needle density is 65 needles / cm. 2 The surface texture is trimmed into a wavy shape and then sintered. The sintering temperature is first increased to 600℃ at a rate of 1℃ / min, then increased to 1400℃ at a rate of 5℃ / min, and held for 2 hours to obtain the upper filter layer.

[0033] The method for preparing the support layer includes the following steps:

[0034] S1-1. Add cellulose microcrystals to water to prepare a cellulose solution with a concentration of 2wt%;

[0035] S1-2. The cellulose solution was added to a mold and subjected to directional freeze-drying at a temperature of -80℃ for 20 hours to obtain cellulose aerogel;

[0036] The method for preparing the lower filter layer includes the following steps:

[0037] S2-1. Cellulose microcrystal is added to water to configure a cellulose solution with a concentration of 2wt%;

[0038] S2-2. Kaolin is added to the cellulose solution, the content of kaolin in the cellulose solution is 2.5wt%, stirring and ultrasonic, then poured into a mold, freeze-drying, freeze-drying temperature is -60℃, time is 20h, to obtain a white mixed aerogel; S2-3. The white mixed aerogel is carbonized, in N2 atmosphere, from room temperature to 350℃ and keep for 30min, continue to heat to 800℃ and keep for 60min, to obtain a carbonized aerogel;

[0039] S2-4. After the carbonized aerogel is added to the thionyl chloride and reacted, washed and vacuum dried, then added to the ethylenediamine and stirred at 100℃ for 10h, cooled to room temperature, washed to remove the ethylenediamine, to obtain a porous cellulose carbon aerogel layer.

[0040] Example 2

[0041] A composite filter material for treating organic wastewater, the composite filter material comprises an upper filter layer, a support layer and a lower filter layer, which are combined into a three-layer filter material by adhesive or needle punching, the upper filter layer adopts an electrospun layer of flocking, the support layer is a directional porous cellulose aerogel layer, and the lower filter layer is a porous cellulose carbon aerogel layer, wherein the thickness of the upper filter layer is 0.8cm, the thickness of the support layer is 0.3cm, and the thickness of the porous cellulose carbon aerogel layer is 0.3cm, the thickness of the electrospun layer in the upper filter layer is 0.1cm, and the rest is flocking.

[0042] The preparation method of the upper filter layer comprises the following steps:

[0043] S1. Aluminum isopropoxide is added to water, heated to reflux and reacted, then nitric acid solution is added, the molar ratio of aluminum isopropoxide, water and nitric acid is 2:130:1, stirring and reaction to obtain an aluminum sol, PVP alcohol solution is added to the aluminum sol, and stirring to obtain an electrospinning solution;

[0044] S2. The electrospinning solution is electrospun to obtain a white electrospun film;

[0045] S3. Aluminum chloride and aluminum isopropoxide are added to a 4mol / L nitric acid solution, heated to reflux and reacted, then aluminum powder is added, the molar ratio of aluminum chloride, aluminum isopropoxide and aluminum powder is 1.2:1.2:2.5, to obtain an aluminum sol, silicon sol is added, the mass ratio of the aluminum sol and the silicon sol is 10:2, the sol is aged to obtain a spinnable precursor sol, and the sol is dry spun to obtain an alumina gel fiber;

[0046] S4. The alumina gel fiber is planted on the surface of the electrospinning membrane by needle punching and flocking, the pre-needling density of the needle punching is 70 needles / cm 2 , the main needle punching density is 80 needles / cm 2 , the surface flock is trimmed into a wave form, and then sintered, the sintering temperature is first increased to 550 DEG C at a rate of 1 DEG C / min, then increased to 1200 DEG C at a rate of 3 DEG C / min, and kept for 2h, to obtain the upper filter layer;

[0047] The preparation method of the support layer comprises the following steps:

[0048] S1-1. Cellulose microcrystal is added to water to configure a cellulose solution with a concentration of 4wt%;

[0049] S1-2. The cellulose solution is added to a mold for directional freeze drying, the temperature of the directional freeze drying is -60 DEG C, and the time is 40h, to obtain a cellulose aerogel;

[0050] The preparation method of the lower filter layer comprises the following steps:

[0051] S2-1. Cellulose microcrystal is added to water to configure a cellulose solution with a concentration of 4wt%;

[0052] S2-2. Kaolin is added to the cellulose solution, the content of the kaolin in the cellulose solution is 4.5wt%, stirred and ultrasonically treated, then poured into a mold, and freeze dried, the freeze drying temperature is -20 DEG C, and the time is 40h, to obtain a white mixed aerogel; S2-3. The white mixed aerogel is carbonized, in a N2 atmosphere, from room temperature to 350 DEG C and kept for 30min, and then continuously increased to 650 DEG C and kept for 60min, to obtain a carbonized aerogel;

[0053] S2-4. After the carbonized aerogel is added to thionyl chloride for reaction, washed and vacuum dried, it is added to ethylenediamine for stirring at 100 DEG C for 20h, cooled to room temperature, and washed to remove the ethylenediamine, to obtain a porous cellulose carbon aerogel layer.

[0054] Example 3

[0055] A composite filter material for treating organic wastewater, the composite filter material comprises an upper filter layer, a support layer and a lower filter layer, which are combined into a three-layer filter material by adhesive or needle punching, the upper filter layer is an electrospinning layer planted by flocking, the support layer is a directional porous cellulose aerogel layer, and the lower filter layer is a porous cellulose carbon aerogel layer, wherein the thickness of the upper filter layer is 0.5cm, the thickness of the support layer is 0.3cm, and the thickness of the porous cellulose carbon aerogel layer is 0.3cm, the thickness of the electrospinning layer in the upper filter layer is 0.1cm, and the rest is flocking;

[0056] The preparation method of the upper filter layer comprises the following steps:

[0057] S1. Add aluminum isopropoxide into water, heat to reflux and react, then add nitric acid solution, the molar ratio of aluminum isopropoxide, water and nitric acid is 1.2:108:0.6, stir to obtain an aluminum sol, add PVP alcohol solution into the aluminum sol, and stir to obtain an electrostatic spinning solution;

[0058] S2. Perform electrostatic spinning on the spinning solution to obtain a white electrostatic spinning film;

[0059] S3. Add aluminum chloride and aluminum isopropoxide into a 2 mol / L nitric acid solution, heat to reflux and react, then add aluminum powder, the molar ratio of aluminum chloride, aluminum isopropoxide and aluminum powder is 1.2:1.2:2.5, to obtain an aluminum sol, add silica sol, the mass ratio of the aluminum sol and the silica sol is 10:1.2, age the sol to obtain a spinnable precursor sol, perform dry spinning on the sol to obtain an alumina gel fiber;

[0060] S4. Use needle punching to plant the alumina gel fiber on the surface of the electrostatic spinning film, the pre-needle punching density is 60 needles / cm 2 , the main needle punching density is 70 needles / cm 2 , trim the surface fluff into a wave form, then sinter, the sintering temperature is first increased to 550℃ at a rate of 1℃ / min, then increased to 1250℃ at a rate of 4℃ / min, and keep the temperature for 2h, to obtain the upper filter layer;

[0061] The preparation method of the support layer comprises the following steps:

[0062] S1-1. Add cellulose microcrystal into water to configure a cellulose solution with a concentration of 2.5wt%;

[0063] S1-2. Add the cellulose solution into a mold to perform directional freeze drying, the temperature of the directional freeze drying is-60℃, and the time is 40h, to obtain a cellulose aerogel.

[0064] The preparation method of the lower filter layer comprises the following steps:

[0065] S2-1. Add cellulose microcrystal into water to configure a cellulose solution with a concentration of 2.5wt%;

[0066] S2-2. Add kaolin to the cellulose solution, the content of kaolin in the cellulose solution is 3wt%, stir and ultrasonic, then pour into the mold, freeze-drying, the freeze-drying temperature is -30℃, the time is 40h, to obtain a white mixed aerogel; S2-3. Carbonize the white mixed aerogel, in N2 atmosphere, from room temperature to 350℃ and keep for 30min, continue to heat to 700℃ and keep for 60min, to obtain carbonized aerogel;

[0067] S2-4. After adding the carbonized aerogel into the thionyl chloride solution and reacting, washing and vacuum drying, then adding into the ethylenediamine solution, stirring at 100℃ for 10h, cooling to room temperature, washing to remove ethylenediamine, to obtain a porous cellulose carbon aerogel layer.

[0068] Example 4

[0069] A composite filter material for treating organic wastewater, the composite filter material comprises an upper filter layer, a support layer and a lower filter layer, which are combined into a three-layer filter material by adhesive or needle punching, the upper filter layer adopts an electrospun layer of flocking, the support layer is a directional porous cellulose aerogel layer, and the lower filter layer is a porous cellulose carbon aerogel layer, wherein the thickness of the upper filter layer is 0.6cm, the thickness of the support layer is 0.5cm, and the thickness of the porous cellulose carbon aerogel layer is 0.2cm, the thickness of the electrospun layer in the upper filter layer is 0.1cm, and the rest is flocking.

[0070] The preparation method of the upper filter layer comprises the following steps:

[0071] S1. Add aluminum isopropoxide into water, heat to reflux and react, then add nitric acid solution, the molar ratio of aluminum isopropoxide, water and nitric acid is 1.8:120:0.9, stir to obtain an aluminum sol, then add PVP alcohol solution into the aluminum sol, and stir to obtain an electrospinning solution;

[0072] S2. Electrospinning the electrospinning solution to obtain a white electrospun film;

[0073] S3. Add aluminum chloride and aluminum isopropoxide into a 3mol / L nitric acid solution, heat to reflux and react, then add aluminum powder, the molar ratio of aluminum chloride, aluminum isopropoxide and aluminum powder is 0.5:0.5:1.5, to obtain an aluminum sol, then add silica sol, the mass ratio of the aluminum sol and the silica sol is 10:1.6, age the sol to obtain a spinnable precursor sol, and dry spinning the sol to obtain an alumina gel fiber;

[0074] S4. Flock the alumina gel fiber on the surface of the electrospun film by needle punching, the pre-needling density of the needle punching is 65 needles / cm 2 , and the main needling density is 75 needles / cm 2and the surface velvet is trimmed into a wave form, and then sintered, the sintering temperature is first increased to 600 DEG C at a rate of 1 DEG C / min, then increased to 1350 DEG C at a rate of 5 DEG C / min, and kept for 2h, to obtain the upper filter layer;

[0075] The preparation method of the support layer comprises the following steps:

[0076] S1-1. Cellulose microcrystal is added to water to configure a cellulose solution with a concentration of 3.5wt%;

[0077] S1-2. The cellulose solution is added to a mold for directional freeze drying, the temperature of directional freeze drying is -80 DEG C, and the time is 30h, to obtain a cellulose aerogel;

[0078] The preparation method of the lower filter layer comprises the following steps:

[0079] S2-1. Cellulose microcrystal is added to water to configure a cellulose solution with a concentration of 3.5wt%;

[0080] S2-2. Kaolin is added to the cellulose solution, the content of kaolin in the cellulose solution is 4wt%, stirring and ultrasonic, then poured into a mold, freeze drying, the freeze drying temperature is -50 DEG C, and the time is 20h, to obtain a white mixed aerogel; S2-3. The white mixed aerogel is carbonized, in N2 atmosphere, from room temperature to 350 DEG C and kept for 30min, and then continuously heated to 750 DEG C and kept for 60min, to obtain a carbonized aerogel;

[0081] S2-4. After the carbonized aerogel is added to thionyl chloride for reaction, washed and vacuum dried, then added to ethylenediamine for stirring reaction at 100 DEG C for 20h and cooled to room temperature, the ethylenediamine is removed by washing, to obtain a porous cellulose carbon aerogel layer.

[0082] Example 5

[0083] A composite filter material for treating organic wastewater, the composite filter material comprises an upper filter layer, a support layer and a lower filter layer, which are combined into a three-layer filter material by adhesive or needle punching, the upper filter layer adopts an electrospun layer of flocking, the support layer is a directional porous cellulose aerogel layer, and the lower filter layer is a porous cellulose carbon aerogel layer, wherein the thickness of the upper filter layer is 0.6cm, the thickness of the support layer is 0.4cm, and the thickness of the porous cellulose carbon aerogel layer is 0.3cm, the thickness of the electrospun layer in the upper filter layer is 0.1cm, and the rest is flocking;

[0084] The preparation method of the upper filter layer comprises the following steps:

[0085] S1. Add aluminum isopropyl alcohol into water, heat to reflux, then add nitric acid solution, the molar ratio of aluminum isopropyl alcohol: water: nitric acid is 1.5:115:0.8, stir to obtain an aluminum sol, then add PVP alcohol solution into the aluminum sol, stir to obtain an electrospinning solution;

[0086] S2. Electrospin the electrospinning solution to obtain a white electrospinning membrane;

[0087] S3. Add aluminum chloride and aluminum isopropyl alcohol into a 3 mol / L nitric acid solution, heat to reflux, then add aluminum powder, the molar ratio of aluminum chloride: aluminum isopropyl alcohol: aluminum powder is 1:1:2, to obtain an aluminum sol, then add silica sol, the mass ratio of the aluminum sol: silica sol is 10:1.5, age the sol to obtain a spinnable precursor sol, then dry-spin the sol to obtain an alumina gel fiber;

[0088] S4. Use needle punching to plant the alumina gel fiber on the surface of the electrospinning membrane, the pre-needle punching density is 60 needles / cm 2 , the main needle punching density is 75 needles / cm 2 , trim the surface fluff into a wave form, then sinter, the sintering temperature is first increased to 580℃ at a rate of 1℃ / min, then increased to 1300℃ at a rate of 4℃ / min, and keep the temperature for 2h, to obtain an upper filter layer;

[0089] The preparation method of the support layer comprises the following steps:

[0090] S1-1. Add cellulose microcrystal into water to prepare a cellulose solution with a concentration of 3wt%;

[0091] S1-2. Add the cellulose solution into a mold for directional freeze drying, the temperature for directional freeze drying is -70℃, and the time is 30h, to obtain a cellulose aerogel;

[0092] The preparation method of the lower filter layer comprises the following steps:

[0093] S2-1. Add cellulose microcrystal into water to prepare a cellulose solution with a concentration of 3wt%;

[0094] S2-2. Add kaolin into the cellulose solution, the content of kaolin in the cellulose solution is 3.5wt%, stir and ultrasonic, then pour into a mold, freeze dry, the freeze drying temperature is -40℃, and the time is 25h, to obtain a white mixed aerogel; S2-3. Carbonize the white mixed aerogel, in a N2 atmosphere, from room temperature to 350℃ and keep the temperature for 30min, continue to increase the temperature to 700℃ and keep the temperature for 60min, to obtain a carbonized aerogel;

[0095] S2-4. After the reaction of adding the carbonized aerogel into the thionyl chloride, washing, vacuum drying, adding into the ethylenediamine, stirring at 100℃ for 15h, cooling to room temperature, washing to remove the ethylenediamine, a porous cellulose carbon aerogel layer is obtained.

[0096] Example 6

[0097] The difference between this example and Example 1 is that the thickness of the upper filter layer in this example is 0.6cm.

[0098] Example 7

[0099] The difference between this example and Example 1 is that the thickness of the upper filter layer in this example is 0.8cm.

[0100] Comparative Example 1

[0101] A composite filter material for treating organic wastewater, the composite filter material comprising an upper filter layer and a lower filter layer, the upper filter layer and the lower filter layer being combined into a two-layer filter material by means of an adhesive or needle punching, the upper filter layer being an electrospun layer of flocking, and the lower filter layer being a porous cellulose carbon aerogel layer, wherein the thickness of the upper filter layer is 0.8cm, the thickness of the porous cellulose carbon aerogel layer is 0.4cm, the thickness of the electrospun layer in the upper filter layer is 0.1cm, and the rest is flocking;

[0102] The preparation method of the upper filter layer comprises the following steps:

[0103] S1. Add aluminum isopropoxide into water, heat to reflux and react, then add nitric acid solution, the molar ratio of aluminum isopropoxide, water and nitric acid is 1:100:0.5, stir to obtain an aluminum sol, then add PVP alcohol solution into the aluminum sol and stir to obtain an electrospinning solution;

[0104] S2. Electrospinning the electrospinning solution to obtain a white electrospun film;

[0105] S3. Add aluminum chloride and aluminum isopropoxide into a 2mol / L nitric acid solution, heat to reflux and react, then add aluminum powder, the molar ratio of aluminum chloride, aluminum isopropoxide and aluminum powder is 0.5:0.5:1.5, to obtain an aluminum sol, then add silica sol, the mass ratio of the aluminum sol and the silica sol is 10:1, age the sol to obtain a spinnable precursor sol, then dry-spin the sol to obtain an alumina gel fiber;

[0106] S4. Flock the surface of the electrospun film by needle punching flocking of the alumina gel fiber, the pre-needling density of the needle punching is 55 needles / cm 2 , and the main needling density is 65 needles / cm 2and the surface of the velvet is trimmed into a wave form, and then sintered, the sintering temperature is first increased to 600 DEG C at a rate of 1 DEG C / min, then increased to 1400 DEG C at a rate of 5 DEG C / min, and kept for 2h, to obtain the upper filter layer;

[0107] The preparation method of the lower filter layer comprises the following steps:

[0108] S2-1. Cellulose microcrystal is added to water to configure a cellulose solution with a concentration of 2wt%;

[0109] S2-2. Kaolin is added to the cellulose solution, the content of kaolin in the cellulose solution is 2.5wt%, stirring and ultrasonic, then poured into a mold, freeze-dried, the freeze-drying temperature is-60 DEG C, the time is 20h, to obtain a white mixed aerogel; S2-3. The white mixed aerogel is carbonized, in N2 atmosphere, from room temperature to 350 DEG C and kept for 30min, continue to increase the temperature to 800 DEG C and keep for 60min, to obtain a carbonized aerogel;

[0110] S2-4. After the carbonized aerogel is added to thionyl chloride and reacted, washed and vacuum dried, then added to ethylenediamine and stirred at 100 DEG C for 10h, cooled to room temperature, washed to remove ethylenediamine, to obtain a porous cellulose carbon aerogel layer.

[0111] Comparative Example 2

[0112] A composite filter material for treating organic wastewater, the composite filter material comprises an upper filter layer, a support layer and a lower filter layer, which are combined into a three-layer filter material by adhesive or needle punching, the upper filter layer is an aluminum oxide electrospinning layer, the support layer is a directional porous cellulose aerogel layer, and the lower filter layer is a porous cellulose carbon aerogel layer, wherein the thickness of the upper filter layer is 0.2cm, the thickness of the support layer is 0.4cm, and the thickness of the porous cellulose carbon aerogel layer is 0.3cm;

[0113] The preparation method of the upper filter layer comprises the following steps:

[0114] S1. Aluminum isopropoxide is added to water, heated to reflux and reacted, then nitric acid solution is added, the molar ratio of aluminum isopropoxide: water: nitric acid is 1.5: 115: 0.8, stirring and reaction to obtain an aluminum sol, PVP alcohol solution is added to the aluminum sol, stirring to obtain an electrospinning solution;

[0115] S2. The spinning solution is electrospun to obtain a white electrospinning film, which is then sintered, the sintering temperature is first increased to 580 DEG C at a rate of 1 DEG C / min, then increased to 1300 DEG C at a rate of 3 DEG C / min, and kept for 2h, to obtain the upper filter layer;

[0116] The method for preparing the support layer includes the following steps:

[0117] S1-1. Add cellulose microcrystals to water to prepare a cellulose solution with a concentration of 3wt%;

[0118] S1-2. The cellulose solution was added to a mold and subjected to directional freeze-drying at a temperature of -70℃ for 30 hours to obtain cellulose aerogel.

[0119] The method for preparing the lower filter layer includes the following steps:

[0120] S2-1. Add cellulose microcrystals to water to prepare a cellulose solution with a concentration of 3wt%;

[0121] S2-2. Kaolin was added to the cellulose solution, with the kaolin content in the cellulose solution being 3.5 wt%. The mixture was stirred and sonicated, then poured into a mold and freeze-dried at -40℃ for 25 h to obtain a white mixed aerogel. S2-3. The white mixed aerogel was carbonized in a N2 atmosphere, from room temperature to 350℃ and held for 30 min, then the temperature was further increased to 700℃ and held for 60 min to obtain a carbonized aerogel.

[0122] S2-4. After adding the carbonized aerogel to thionyl chloride for reaction, it is washed and vacuum dried, then added to ethylenediamine and stirred at 100°C for 15 h. After cooling to room temperature, the ethylenediamine is washed away to obtain a porous cellulose carbon aerogel layer.

[0123] Comparative Example 3

[0124] The difference between Comparative Example 3 and Example 5 is that the flocking thickness is uniformly 0.7cm and is not a wavy structure;

[0125] Comparative Example 4

[0126] A composite filter material for treating organic wastewater includes an upper filter layer, a support layer, and a lower filter layer, which are bonded together by an adhesive or needle punch to form a three-layer filter material. The upper filter layer is a flocked electrospun layer, the support layer is a directional porous cellulose aerogel layer, and the lower filter layer is a porous cellulose carbon aerogel layer. The thickness of the upper filter layer is 0.6 cm, the thickness of the support layer is 0.4 cm, the thickness of the porous cellulose carbon aerogel layer is 0.3 cm, the thickness of the electrospun layer in the upper filter layer is 0.1 cm, and the remainder is flocked.

[0127] The method for preparing the upper filter layer includes the following steps:

[0128] S1. Add aluminum isopropyl alcohol into water, heat to reflux, then add nitric acid solution, the molar ratio of aluminum isopropyl alcohol: water: nitric acid is 1.5:115:0.8, stir to obtain an aluminum sol, then add PVP alcohol solution into the aluminum sol, stir to obtain an electrospinning solution;

[0129] S2. Electrospin the electrospinning solution to obtain a white electrospinning membrane;

[0130] S3. Add aluminum chloride and aluminum isopropyl alcohol into a 3 mol / L nitric acid solution, heat to reflux, then add aluminum powder, the molar ratio of aluminum chloride: aluminum isopropyl alcohol: aluminum powder is 1:1:2, to obtain an aluminum sol, then add silica sol, the mass ratio of the aluminum sol: silica sol is 10:1.5, age the sol to obtain a spinnable precursor sol, then dry-spin the sol to obtain an alumina gel fiber;

[0131] S4. Use needle punching to plant the alumina gel fiber on the surface of the electrospinning membrane, the pre-needle punching density is 60 needles / cm 2 , the main needle punching density is 75 needles / cm 2 , trim the surface fluff into a wave form, then sinter, the sintering temperature is first increased to 580℃ at a rate of 1℃ / min, then increased to 1300℃ at a rate of 4℃ / min, and keep the temperature for 2h, to obtain an upper filter layer;

[0132] The preparation method of the support layer comprises the following steps:

[0133] S1-1. Add cellulose microcrystal into water to prepare a cellulose solution with a concentration of 3wt%;

[0134] S1-2. Add the cellulose solution into a mold for directional freeze drying, the temperature for directional freeze drying is -70℃, and the time is 30h, to obtain a cellulose aerogel;

[0135] The preparation method of the lower filter layer comprises the following steps:

[0136] S2-1. Add cellulose microcrystal into water to prepare a cellulose solution with a concentration of 3wt%;

[0137] S2-2. Pour the cellulose solution into a mold for freeze drying, the temperature for freeze drying is -40℃, and the time is 25h, to obtain a white mixed aerogel;

[0138] S2-3. Carbonize the white mixed aerogel, in a N2 atmosphere, from room temperature to 350℃ and keep the temperature for 30min, then continue to increase the temperature to 700℃ and keep the temperature for 60min, to obtain a carbonized aerogel;

[0139] S2-4. After the reaction of the carbonized aerogel into the thionyl chloride, washing and vacuum drying, then adding into the ethylenediamine, stirring at 100℃ for 15h, cooling to room temperature, washing to remove the ethylenediamine, obtaining the porous cellulose carbon aerogel layer.

[0140] Comparative Example 5

[0141] A composite filter material for treating organic wastewater, the composite filter material comprising an upper filter layer, a support layer and a lower filter layer, the three layers of filter material being combined by adhesive or needle punching, the upper filter layer being an electrospun layer of flocking, the support layer being a directional porous cellulose aerogel layer, and the lower filter layer being a porous cellulose carbon aerogel layer, wherein the thickness of the upper filter layer is 0.6cm, the thickness of the support layer is 0.4cm, and the thickness of the porous cellulose carbon aerogel layer is 0.3cm, the thickness of the electrospun layer in the upper filter layer is 0.1cm, and the rest is flocking;

[0142] The preparation method of the upper filter layer comprises the following steps:

[0143] S1. Adding aluminum isopropoxide into water, heating to reflux, then adding nitric acid solution, the molar ratio of aluminum isopropoxide, water and nitric acid being 1.5:115:0.8, stirring to obtain an aluminum sol, then adding a PVP alcohol solution into the aluminum sol, and stirring to obtain an electrospinning solution;

[0144] S2. Electrospinning the electrospinning solution to obtain a white electrospun film;

[0145] S3. Adding aluminum chloride and aluminum isopropoxide into a 3mol / L nitric acid solution, heating to reflux, then adding aluminum powder, the molar ratio of aluminum chloride, aluminum isopropoxide and aluminum powder being 1:1:2, to obtain an aluminum sol, then adding a silica sol, the mass ratio of the aluminum sol and the silica sol being 10:1.5, aging the sol to obtain a spinnable precursor sol, and dry spinning the sol to obtain an alumina gel fiber;

[0146] S4. Flocking the alumina gel fiber on the surface of the electrospun film by needle punching, the pre-needling density of the needle punching being 60 needles / cm 2 , the main needle punching density being 75 needles / cm 2 , trimming the surface flocking into a wave form, and then sintering, the sintering temperature being first raised to 580℃ at a rate of 1℃ / min, then raised to 1300℃ at a rate of 4℃ / min, and keeping the temperature for 2h, to obtain the upper filter layer;

[0147] The preparation method of the support layer comprises the following steps:

[0148] S1-1. Adding cellulose microcrystal into water to prepare a cellulose solution with a concentration of 3wt%;

[0149] S1-2. The cellulose solution is added to a mold for directional freeze drying at a temperature of -70 DEG C for 30 h to obtain a cellulose aerogel;

[0150] The preparation method of the lower filter layer comprises the following steps:

[0151] S2-1. Cellulose microcrystals are added to water to prepare a cellulose solution with a concentration of 3 wt%;

[0152] S2-2. Kaolin is added to the cellulose solution, and the content of the kaolin in the cellulose solution is 3.5 wt%. After stirring and ultrasonic treatment, the mixture is poured into a mold and freeze-dried at a temperature of -40 DEG C for 25 h to obtain a white mixed aerogel; S2-3. The white mixed aerogel is carbonized in a N2 atmosphere, and the temperature is increased from room temperature to 350 DEG C and maintained for 30 min, and then the temperature is increased to 700 DEG C and maintained for 60 min to obtain a porous cellulose carbon aerogel layer.

[0153] Comparative Example 6

[0154] The difference between Comparative Example 6 and Example 1 is that the thickness of the upper filter layer in the present example is 0.2 cm.

[0155] Different concentrations of wastewater from a textile factory were treated under different hydraulic load conditions, and the treatment results are shown in Table 1 and Table 2 below:

[0156] Table 1

[0157] Turbidity / NTU COD / mg / L Example 1 42.6 235 Example 2 41.9 218 Example 3 39.8 225 Example 4 38.5 221 Example 5 38.6 209 Example 6 39.8 230 Example 7 38.6 225 Comparative Example 1 108.6 482 Comparative Example 2 112.8 369 Comparative Example 3 61.9 301 Comparative Example 4 55.7 398 Comparative Example 5 51.3 421 Comparative Example 6 75.9 252

[0158] Note: In Table 1 above, the hydraulic load of the wastewater through the filter material is 0.2 m 3 / m 2 ·h -1 , and the initial COD concentration in the wastewater is 3240 mg / L, and the turbidity is 1960 NTU.

[0159] Table 2

[0160]

[0161]

[0162] Note: In Table 2 above, the hydraulic load of the wastewater through the filter material is 0.4 m 3 / m 2 ·h -1 , and the initial COD concentration in the wastewater is 3240 mg / L, and the turbidity is 1960 NTU.

[0163] Obviously, the above embodiments are merely example for clearly illustrating but not limitation to the embodiments. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. Here, all the embodiments need not and can not be enumerated. The obvious changes or variations derived from the above description are still within the protection scope of the present application.

Claims

1. A composite filter material for treating organic wastewater, characterized in that: The composite filter material comprises an upper filter layer, a support layer, and a lower filter layer, which are bonded together as a three-layer filter material by adhesive or needle punching. The upper filter layer is a flocked electrospun layer, the support layer is a directional porous cellulose aerogel layer, and the lower filter layer is a porous cellulose carbon aerogel layer. The thickness of the upper filter layer is 0.4-0.8 cm, the thickness of the support layer is 0.3-0.5 cm, and the thickness of the porous cellulose carbon aerogel layer is 0.2-0.3 cm. The method for preparing the upper filter layer includes the following steps: S1. Add aluminum isopropoxide to water, heat and reflux to react, then add nitric acid solution, stir to react, and obtain aluminum sol. Add PVP alcohol solution to aluminum sol and stir to obtain electrospinning solution. S2. Electrospin the spinning solution to obtain a white electrospun film; S3. Add aluminum chloride and aluminum isopropoxide to a nitric acid solution, heat and reflux to react, then add aluminum powder to obtain aluminum sol, then add silica sol, age the sol to obtain a spinnable precursor sol, and dry spin the sol to obtain alumina gel fiber. S4. Alumina gel fibers are needle-punched and flocked onto the surface of the electrospun membrane, and the flocking on the surface is trimmed into a wavy shape before sintering to obtain the upper filter layer. The method for preparing the support layer includes the following steps: S1-1. Add cellulose microcrystals to water to prepare a cellulose solution with a concentration of 2-4 wt%; S1-2. The cellulose solution is added to the mold and subjected to directional freeze-drying at a temperature of -80~-60℃ for 20-40h to obtain cellulose aerogel; The method for preparing the lower filter layer includes the following steps: S2-1. Add cellulose microcrystals to water to prepare a cellulose solution with a concentration of 2-4 wt%; S2-2. Kaolin is added to the cellulose solution, with the kaolin content in the cellulose solution being 2.5-4.5 wt%. The mixture is stirred and sonicated, then poured into a mold and freeze-dried at a temperature of -60 to -20°C for 20-40 hours to obtain a white mixed aerogel. S2-3. Carbonize the white mixed aerogel by raising the temperature from room temperature to 350 ℃ and holding it for 30 min in a N2 atmosphere, then raising the temperature to 650-800 ℃ and holding it for 60 min to obtain carbonized aerogel. S2-4. After the carbonized aerogel is added to thionyl chloride and reacted, it is washed and dried under vacuum. Then it is added to ethylenediamine and stirred at 100°C for 10-20 h. After cooling to room temperature, the ethylenediamine is washed away to obtain a porous cellulose carbon aerogel layer.

2. The composite filter material for treating organic wastewater according to claim 1, characterized in that: In step S1, the molar ratio of aluminum isopropoxide:water:nitric acid is 1-2:100-130:0.5-1.

3. The composite filter material for treating organic wastewater according to claim 1, characterized in that: In step S3, the molar ratio of aluminum chloride, aluminum isopropoxide, and aluminum powder is 1:1:2, the mass ratio of aluminum sol to silica sol is 10:1-2, and the concentration of nitric acid solution is 2-4 mol / L.

4. The composite filter material for treating organic wastewater according to claim 1, characterized in that: In step S4, the pre-needle density is 55-70 needles / cm². 2 The main needle density is 65-80 needles / cm. 2 The sintering temperature is first increased to 550-600℃ at a rate of 1℃ / min, then increased to 1200-1400℃ at a rate of 3-5℃ / min, and held at that temperature for 2 hours.

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