A composite membrane applied to industrial wastewater treatment

Abstract

The application provides a composite membrane applied to industrial wastewater treatment. The composite membrane has a three-layer structure, the first layer is a hollow porous iron oxide microfiltration membrane with a thickness of 30-80 mu m, the middle layer is adsorption particles with a thickness of 30-60 mu m, and the third layer is an iron oxide nanofiltration membrane with a thickness of 100-500 mu m; the pore size of the hollow porous iron oxide microfiltration membrane is 0.1-10 mu m; the adsorption particles are pollen carbon particles with a particle size of 10-30 mu m; and the pore size of the iron oxide nanofiltration membrane is 1-2 nm. The composite membrane used in the application has a three-layer structure, adsorption particles are fixed in the middle of the two layers of membranes, the first layer of membrane is a microfiltration membrane with a pore size of 0.1-10 mu m, mainly removing suspended large particles, the middle layer of adsorption particles mainly adsorbing monovalent salt, and the third layer is a nanofiltration membrane with a pore size of 1-2 nm, mainly used for removing small-molecule organic matters and divalent salt or multivalent salt. The three-layer structure effectively solves the defect that the property of the matrix membrane is affected when the matrix membrane and the particles are blended.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of water treatment, and in particular to a composite membrane applied to industrial wastewater treatment. BACKGROUND

[0002] The shortage of clean water resources has become one of the major challenges facing the world. The World Health Organization's annual report in 2018 shows that there are still 2 billion people in the world who drink contaminated water, and 4.5 billion people do not have effective purification systems to treat water. Membrane separation technology is a separation technology that uses the selective permeability of a separation membrane, and uses pressure difference, concentration difference, potential difference, temperature difference, etc. as the driving force to separate, concentrate and purify different components in the feed liquid. Water treatment technology based on membrane separation has the advantages of high treatment efficiency, small land occupation, easy modularization and automatic control, and has been widely used in various fields of water treatment. It plays an important role in addressing water shortages, ensuring drinking water safety and water pollution control. The effect of pure membrane is limited, and it is usually necessary to modify and prepare functional membranes. The preparation of functional membranes usually has blending method and self-assembly method, among which, the blending modification is to blend the filler with the membrane matrix to prepare, which can make the membrane obtain the functional characteristics of the filler and improve the membrane effect. However, the filler is embedded in the membrane layer, which will face the problems of poor compatibility between the filler and the membrane matrix, leading to filler overflow and membrane defects, and easy aggregation of the filler. Therefore, how to improve this shortcoming and further improve the water treatment effect is the research focus of the present application. SUMMARY

[0003] The technical problem to be solved is that in view of the above technical problems, the purpose of the present application is to provide a composite membrane applied to industrial wastewater treatment. The composite membrane has a three-layer structure, two layers of membranes have adsorption particles fixed in the middle, the first layer of membrane is a microfiltration membrane with a pore size of 0.1-10 μm, mainly removing suspended large particles, the middle layer of adsorption particles mainly adsorbing monovalent salt, and the third layer is a nanofiltration membrane with a pore size of 1-2 nm, mainly used for removing small molecule organic matter and divalent or multivalent salt. This three-layer structure effectively solves the problem that the blending of the base membrane and the particles will affect the properties of the base membrane.

[0004] Technical scheme: A composite membrane applied to industrial wastewater treatment, the composite membrane has a three-layer structure, the first layer is a hollow porous iron oxide microfiltration membrane with a thickness of 30-80 μm, the middle layer is an adsorption particle with a thickness of 30-60 μm, and the third layer is an iron oxide nanofiltration membrane with a thickness of 100-500 μm.

[0005] Further, the pore size of the hollow porous iron oxide microfiltration membrane is 0.1-10 μm.

[0006] Further, the adsorption particles are pollen carbon particles with a particle size of 10-30 μm.

[0007] Further, the pore size of the iron oxide nanofiltration membrane is 1-2 nm.

[0008] The preparation method of the composite membrane for industrial wastewater treatment comprises the following steps:

[0009] (1) Take 8 parts of hydrated ferric chloride, add 50 parts of anhydrous ethanol, stir and dissolve, add 6 parts of acetylacetone, stir uniformly, then heat in a 50°C water bath and add 3-5 parts of epoxy chloropropane under stirring, after 4h of incubation and stirring, add 1-2 parts of nano calcium carbonate particles, stir uniformly, to obtain a shell sol spinning solution;

[0010] (2) Mix polyvinyl alcohol powder and water, heat and stir to dissolve, to obtain a core layer spinning solution with a polyvinyl alcohol content of 8-10wt.%;

[0011] (3) Obtain a first layer of electrospun membrane by using coaxial electrospinning method;

[0012] (4) Uniformly lay a layer of pollen on the first layer of electrospun membrane to obtain a middle pollen layer;

[0013] (5) Take 8 parts of hydrated ferric chloride, add 50 parts of anhydrous ethanol, stir and dissolve, add 6 parts of acetylacetone, stir uniformly, then heat in a 50°C water bath and add 3-5 parts of epoxy chloropropane under stirring, after 5h of incubation and stirring, to obtain a sol spinning solution;

[0014] (6) Load the sol spinning solution into an electrospinning device, and continue to receive a third layer of electrospun membrane on the pollen layer by using electrospinning method;

[0015] (7) Place in a high-temperature sintering furnace, calcine at a temperature of 700-1000°C for 5-8h, wash with dilute hydrochloric acid, and then wash with water;

[0016] (8) Place in a drying oven at 60°C for drying.

[0017] Further, the coaxial electrospinning conditions in step (3) are as follows: select two syringes, place them on two propulsion devices, and connect them to a coaxial needle with a polytetrafluoroethylene tube, the inner diameter of the outer needle is 0.86 mm, the outer diameter is 1.26 mm, the inner diameter of the inner needle is 0.33 mm, and the outer diameter is 0.63 mm, the voltage is 15-20 kV, the shell sol spinning solution flow rate is 1.0 mL / h, the core layer spinning solution flow rate is 0.15-0.25 mL / h, the distance between the needle tip and the collector is fixed at 15 cm, the electrospinning temperature is 25°C, and the relative humidity is 50%.

[0018] Further, the pollen in step (4) includes corn pollen, tea pollen, buckwheat pollen, rape pollen, and dandelion pollen.

[0019] Further, the electrospinning conditions in step (6) are as follows: the inner diameter of the needle is 0.16 mm, the voltage is 15-20 kV, the flow rate of the sol spinning solution is 1.0-1.5 mL / h, the ambient temperature is 25 DEG C, the humidity is 50%, and the distance from the needle to the receiving plate is 17 cm.

[0020] Advantages:

[0021] 1. The composite membrane used in the application has a three-layer structure, the adsorbing particles are fixed in the middle of the two layers of membranes, the first layer of membrane is a microfiltration membrane with a pore size of 0.1-10 um, mainly removing suspended large particles, the middle layer of adsorbing particles mainly adsorbing monovalent salt, and the third layer is a nanofiltration membrane with a pore size of 1-2 nm, mainly used for removing small-molecule organic matter and divalent or multivalent salt. The three-layer structure effectively solves the problem that the blending of the base membrane and the particles will affect the properties of the base membrane.

[0022] 2. The microfiltration membrane in the application is a hollow porous iron oxide microfiltration membrane, which is formed into a double-layer structure by coaxial electrospinning, and then sintered to form an iron oxide hollow structure. After washing the calcium carbonate with dilute hydrochloric acid, nano-porous is formed, which greatly improves the specific surface area, so that it has good adsorption of metal ions while having the effect of filtration.

[0023] 3. The adsorbing particles in the application are pollen carbon particles. Pollen is a natural porous material with a large specific surface area, and carbon also has good adsorption effect. However, if the blending method is used to add the particles into the membrane, on the one hand, the contact area will be reduced, and on the other hand, the mechanical properties and activity of the membrane matrix will be affected, and agglomeration will also occur. Therefore, the material is uniformly fixed between the two layers of membranes.

[0024] 4. The nanofiltration membrane in the application is an iron oxide nanofiltration membrane, which has the effect of nanofiltration of the membrane itself and further plays an adsorbing role.

[0025] 5. The material of the microfiltration membrane and the nanofiltration membrane in the application is iron oxide, which has adsorption effect and can withstand stronger pressure, can be reused, and has a service life of several tens of times of conventional microfiltration membranes and nanofiltration membranes. The pore size and thickness of the membrane can be controlled. Although the preparation process is more complex than that of conventional membranes, the effect is much better after comprehensive comparison, and the final cost is also lower than that of conventional membranes. DETAILED DESCRIPTION

[0026] The application proposes a composite membrane applied to industrial wastewater treatment. In order to make the purpose, technical scheme and effect of the application more clear and definite, the application will be further described in detail in combination with examples. It should be understood that the specific examples described herein are only used to explain the application and not to limit the application.

[0027] Example 1

[0028] Different proportions of nano calcium carbonate are used, and the specific proportions are as follows:

[0029] A preparation method of a composite membrane applied to industrial wastewater treatment, comprising the following steps:

[0030] (1) 8 parts of hydrated ferric chloride are taken, 50 parts of anhydrous ethanol are added, stirring and dissolving, 6 parts of acetylacetone are added, stirring uniformly, then 4 parts of epoxy chloropropane are added under stirring at 50 DEG C water bath heating, and after 4h of temperature preservation and stirring, 1 part, 1.5 parts and 2 parts of nano calcium carbonate particles are added respectively, stirring uniformly, to obtain a shell sol spinning solution;

[0031] (2) polyvinyl alcohol powder and water are mixed, heated and stirred to dissolve, to obtain a core layer spinning solution with a polyvinyl alcohol content of 9wt.%;

[0032] (3) a first layer of electrospun film is obtained by using a coaxial electrospinning method, and the coaxial electrospinning conditions are as follows: two injectors are placed on two propulsion devices and connected to a coaxial needle by a polytetrafluoroethylene tube, the inner diameter of the outer needle is 0.86 mm, the outer diameter is 1.26 mm, the inner diameter of the inner needle is 0.33 mm, the outer diameter is 0.63 mm, the voltage is 18 kV, the flow rate of the shell sol spinning solution is 1.0 mL / h, the flow rate of the core layer spinning solution is 0.2 mL / h, the distance between the needle tip and the collector is fixed at 15 cm, the electrospinning temperature is 25 DEG C, and the relative humidity is 50%;

[0033] (4) a layer of tea flower powder is evenly laid on the first layer of electrospun film to obtain an intermediate tea flower powder layer;

[0034] (5) 8 parts of hydrated ferric chloride are taken, 50 parts of anhydrous ethanol are added, stirring and dissolving, 6 parts of acetylacetone are added, stirring uniformly, then 4 parts of epoxy chloropropane are added under stirring at 50 DEG C water bath heating, and after 5h of temperature preservation and stirring, a sol spinning solution is obtained;

[0035] (6) the sol spinning solution is loaded into an electrospinning device, and a third layer of electrospun film is continuously received on the powder layer by using an electrospinning method, and the electrospinning conditions are as follows: the inner diameter of the needle is 0.16 mm, the voltage is 18 kV, the flow rate of the sol spinning solution is 1.3 mL / h, the environmental temperature is 25 DEG C, the humidity is 50%, and the distance from the receiving plate is 17 cm;

[0036] (7) it is placed in a high-temperature sintering furnace, calcined at a temperature of 1000 DEG C for 5h, washed with dilute hydrochloric acid, and then washed with water;

[0037] (8) it is placed in a drying box at 60 DEG C for drying, and the composite membrane is obtained.

[0038] Composite membrane No. 1, composite membrane No. 2 and composite membrane No. 3 are obtained respectively, and the composite membranes are three-layer structures, the first layer is a hollow porous iron oxide microfiltration membrane with a thickness of 60 μm, a pore size of 0.1-10 μm, the middle layer is an adsorption particle with a thickness of 45 μm, a particle size of 10-30 μm, and the third layer is an iron oxide nanofiltration membrane with a thickness of 300 μm, a pore size of 1-2 nm.

[0039] Example 2

[0040] Different concentrations of polyvinyl alcohol are used, and the specific conditions are as follows:

[0041] A preparation method of a composite membrane applied to industrial wastewater treatment, comprising the following steps:

[0042] (1) Take 8 parts of hydrated ferric chloride, add 50 parts of anhydrous ethanol, stir to dissolve, add 6 parts of acetylacetone, stir uniformly, then heat in a 50℃ water bath and add 4 parts of epichlorohydrin under stirring, stir for 4 h, then add 1.5 parts of nano calcium carbonate particles, stir uniformly, to obtain a shell sol spinning solution;

[0043] (2) Mix polyvinyl alcohol powder and water, heat and stir to dissolve, to obtain a core layer spinning solution with a polyvinyl alcohol content of 8wt.% and 10wt.%;

[0044] (3) A first layer of electrospun film is obtained by using coaxial electrospinning method, and the coaxial electrospinning conditions are as follows: two injectors are placed on two propulsion devices and connected to a coaxial needle by a polytetrafluoroethylene tube, the inner diameter of the outer needle is 0.86 mm, the outer diameter is 1.26 mm, the inner diameter of the inner needle is 0.33 mm, the outer diameter is 0.63 mm, the voltage is 18 kV, the shell sol spinning solution flow rate is 1.0 mL / h, the core layer spinning solution flow rate is 0.2 mL / h, the distance between the needle tip and the collector is fixed at 15 cm, the electrospinning temperature is 25℃, and the relative humidity is 50%;

[0045] (4) A layer of tea flower powder is evenly laid on the first layer of electrospun film to obtain a middle tea flower powder layer;

[0046] (5) Take 8 parts of hydrated ferric chloride, add 50 parts of anhydrous ethanol, stir to dissolve, add 6 parts of acetylacetone, stir uniformly, then heat in a 50℃ water bath and add 4 parts of epichlorohydrin under stirring, stir for 5 h to obtain a sol spinning solution;

[0047] (6) The sol spinning solution is loaded into an electrospinning device, and a third layer of electrospun film is continuously received on the powder layer by using electrospinning method, and the electrospinning conditions are as follows: the inner diameter of the needle is 0.16 mm, the voltage is 18 kV, the sol spinning solution flow rate is 1.3 mL / h, the environmental temperature is 25℃, the humidity is 50%, and the distance from the receiving plate is 17 cm;

[0048] (7) Put in high temperature sintering furnace, calcine at 1000℃ for 5h, wash with dilute hydrochloric acid and then wash with water;

[0049] (8) Dry in 60℃ drying oven to obtain the product.

[0050] Composite membrane No.4 and No.5 are obtained, which are three-layer structures, the first layer is a hollow porous iron oxide microfiltration membrane with a thickness of 60μm, a pore size of 0.1-10μm, the middle layer is an adsorption particle with a thickness of 45μm, a particle size of 10-30μm, and the third layer is an iron oxide nanofiltration membrane with a thickness of 300μm, a pore size of 1-2nm.

[0051] Example 3

[0052] In step (3), different flow rates of core layer spinning solution are used, as follows:

[0053] A preparation method of a composite membrane applied to industrial wastewater treatment, comprising the following steps:

[0054] (1) Take 8 parts of hydrated ferric chloride, add 50 parts of anhydrous ethanol, stir to dissolve, add 6 parts of acetylacetone, stir uniformly, then heat in a 50℃ water bath and add 4 parts of epichlorohydrin under stirring, stir for 4h, then add 1.5 parts of nano calcium carbonate particles, stir uniformly, to obtain a shell layer sol spinning solution;

[0055] (2) Mix polyvinyl alcohol powder and water, heat and stir to dissolve, to obtain a core layer spinning solution with a polyvinyl alcohol content of 9wt.%;

[0056] (3) Obtain a first layer electrospun membrane by coaxial electrospinning, with the following coaxial electrospinning conditions: select two injectors placed on two push devices and connected to a coaxial needle by a polytetrafluoroethylene tube, the outer needle has an inner diameter of 0.86mm and an outer diameter of 1.26mm, the inner needle has an inner diameter of 0.33mm and an outer diameter of 0.63mm, the voltage is 18kV, the shell layer sol spinning solution has a flow rate of 1.0mL / h, the core layer spinning solution has flow rates of 0.15mL / h and 0.25mL / h respectively, the distance between the needle tip and the collector is fixed at 15cm, the electrospinning temperature is 25℃, and the relative humidity is 50%;

[0057] (4) Uniformly lay a layer of tea flower powder on the first layer electrospun membrane to obtain a middle tea flower powder layer;

[0058] (5) Take 8 parts of hydrated ferric chloride, add 50 parts of anhydrous ethanol, stir to dissolve, add 6 parts of acetylacetone, stir uniformly, then heat in a 50℃ water bath and add 4 parts of epichlorohydrin under stirring, stir for 5h to obtain a sol spinning solution;

[0059] (6) The sol spinning solution is loaded into the electrospinning device, and the third layer of electrospinning film is continuously received on the pollen layer by electrospinning method, and the electrospinning conditions are as follows: the inner diameter of the needle is 0.16 mm, the voltage is 18 kV, the flow rate of the sol spinning solution is 1.3 mL / h, the ambient temperature is 25°C, the humidity is 50%, and the distance from the receiving plate is 17 cm;

[0060] (7) Place in a high-temperature sintering furnace, calcine at a temperature of 1000°C for 5h, wash with dilute hydrochloric acid, and then wash with water;

[0061] (8) Place in a drying oven at 60°C and dry to obtain the product.

[0062] Composite film No. 6 and composite film No. 7 are obtained, and the composite film has a three-layer structure, the first layer is a hollow porous iron oxide microfiltration membrane with a thickness of 60μm, the pore size is 0.1-10μm, the middle layer is an adsorbed particle with a thickness of 45μm, the particle size is 10-30μm, and the third layer is an iron oxide nanofiltration membrane with a thickness of 300μm, the pore size is 1-2nm.

[0063] Example 4

[0064] In step (6), different flow rates of sol spinning solution are used, as follows:

[0065] A preparation method of a composite membrane applied to industrial wastewater treatment, comprising the following steps:

[0066] (1) Take 8 parts of hydrated ferric chloride, add 50 parts of anhydrous ethanol, stir to dissolve, add 6 parts of acetylacetone, stir uniformly, then heat in a 50°C water bath and add 4 parts of epichlorohydrin under stirring, stir for 4h, then add 1.5 parts of nano calcium carbonate particles, stir uniformly, to obtain a shell sol spinning solution;

[0067] (2) Mix polyvinyl alcohol powder and water, heat and stir to dissolve, to obtain a core spinning solution with a polyvinyl alcohol content of 9wt.%;

[0068] (3) The first layer of electrospinning film is obtained by coaxial electrospinning, and the coaxial electrospinning conditions are as follows: two syringes are placed on two push devices and connected to the coaxial needle by a polytetrafluoroethylene tube, the inner diameter of the outer needle is 0.86 mm, the outer diameter is 1.26 mm, the inner diameter of the inner needle is 0.33 mm, the outer diameter is 0.63 mm, the voltage is 18 kV, the flow rate of the shell sol spinning solution is 1.0 mL / h, the flow rate of the core spinning solution is 0.2 mL / h, the distance between the needle tip and the collector is fixed at 15 cm, the electrospinning temperature is 25°C, and the relative humidity is 50%;

[0069] (4) A layer of tea pollen is evenly laid on the first layer of electrospinning film to obtain a middle tea pollen layer;

[0070] (5) Take 8 parts of hydrated ferric chloride, add 50 parts of anhydrous ethanol, stir and dissolve, add 6 parts of acetylacetone, stir evenly, then heat in a 50°C water bath and add 4 parts of epichlorohydrin under stirring, and after 5h of incubation and stirring, a sol spinning solution is obtained;

[0071] (6) The sol spinning solution is loaded into an electrospinning device, and an electrospinning method is used to continue receiving a third layer of electrospinning film on the pollen layer, with the following electrospinning conditions: needle inner diameter specification is 0.16 mm, voltage is 18 kV, sol spinning solution flow rate is 1.0 mL / h and 1.5 mL / h, ambient temperature is 25°C, humidity is 50%, and distance from the receiving plate is 17 cm;

[0072] (7) Place in a high-temperature sintering furnace, calcine at a temperature of 1000°C for 5h, wash with dilute hydrochloric acid, and then wash with water;

[0073] (8) Dry in a drying oven at 60°C to obtain the product.

[0074] Composite film No. 8 and composite film No. 9 are obtained, both of which have a three-layer structure, the first layer being a hollow porous iron oxide microfiltration membrane with a thickness of 60μm and a pore size of 0.1-10μm, the middle layer being an adsorbed particle with a thickness of 45μm and a particle size of 10-30μm, and the third layer being an iron oxide nanofiltration membrane with a thickness of 300μm and a pore size of 1-2nm.

[0075] Comparative Example 1

[0076] The difference between this example and composite film No. 2 is that the pollen is directly blended into the hollow porous iron oxide microfiltration membrane, specifically as follows:

[0077] A method for preparing a composite membrane for industrial wastewater treatment, comprising the following steps:

[0078] (1) Take 8 parts of hydrated ferric chloride, add 50 parts of anhydrous ethanol, stir and dissolve, add 6 parts of acetylacetone, stir evenly, then heat in a 50°C water bath and add 4 parts of epichlorohydrin under stirring, and after 4h of incubation and stirring, add 3 parts of tea pollen and 1.5 parts of nano calcium carbonate particles, stir evenly, to obtain a shell sol spinning solution;

[0079] (2) Mix polyvinyl alcohol powder and water, heat and stir to dissolve, to obtain a core spinning solution with a polyvinyl alcohol content of 9wt.%;

[0080] (3) The first layer of electrospun film is obtained by using coaxial electrospinning method, and the coaxial electrospinning conditions are as follows: two syringes are placed on two propulsion devices and connected to a coaxial needle by a polytetrafluoroethylene tube, the inner diameter of the outer needle is 0.86 mm, the outer diameter is 1.26 mm, the inner diameter of the inner needle is 0.33 mm, the outer diameter is 0.63 mm, the voltage is 18 kV, the flow rate of the shell sol spinning solution is 1.0 mL / h, the flow rate of the core spinning solution is 0.2 mL / h, the distance between the needle tip and the collector is fixed at 15 cm, the electrospinning temperature is 25℃, and the relative humidity is 50%;

[0081] (4) Take 8 parts of hydrated ferric chloride, add 50 parts of anhydrous ethanol, stir and dissolve, add 6 parts of acetylacetone, stir uniformly, then heat in a 50℃ water bath and add 4 parts of epichlorohydrin under stirring, and after 5h of incubation and stirring, a sol spinning solution is obtained;

[0082] (5) The sol spinning solution is loaded into an electrospinning device, and a third layer of electrospun film is continuously received on the pollen layer by using electrospinning method, and the electrospinning conditions are as follows: the inner diameter of the needle is 0.16 mm, the voltage is 18 kV, the flow rate of the sol spinning solution is 1.3 mL / h, the environmental temperature is 25℃, the humidity is 50%, and the distance from the receiving plate is 17 cm;

[0083] (6) Place in a high-temperature sintering furnace, calcine at a temperature of 1000℃ for 5h, wash with dilute hydrochloric acid, and then wash with water;

[0084] (7) Place in a 60℃ drying oven and dry to obtain the product.

[0085] A composite membrane No. 10 is obtained, which has a two-layer structure, the first layer is a hollow porous carbon-doped iron oxide microfiltration membrane with a thickness of 60μm and a pore size of 0.1-10μm, and the second layer is an iron oxide nanofiltration membrane with a thickness of 300μm and a pore size of 1-2nm.

[0086] Comparative Example 2

[0087] The difference between this example and composite membrane No. 2 is that the first layer is a solid porous iron oxide microfiltration membrane, which is specifically:

[0088] A method for preparing a composite membrane for industrial wastewater treatment, comprising the following steps:

[0089] (1) Take 8 parts of hydrated ferric chloride, add 50 parts of anhydrous ethanol, stir and dissolve, add 6 parts of acetylacetone, stir uniformly, then heat in a 50℃ water bath and add 4 parts of epichlorohydrin under stirring, and after 5h of incubation and stirring, a sol spinning solution is obtained;

[0090] (3) the sol spinning solution is loaded into the electrospinning device to obtain a first electrospinning film, and the electrospinning conditions are as follows: the inner diameter of the needle is 0.16 mm, the voltage is 18 kV, the flow rate of the first sol spinning solution is 1.0 mL / h, the ambient temperature is 25°C, the humidity is 50%, and the distance from the receiving plate is 15 cm;

[0091] (4) a layer of tea flower powder is evenly laid on the first electrospinning film to obtain a middle tea flower powder layer;

[0092] (5) 8 parts of hydrated ferric chloride are added into 50 parts of anhydrous ethanol, stirred and dissolved, 6 parts of acetylacetone are added, stirred uniformly, then heated in a 50°C water bath and 4 parts of epichlorohydrin are added under stirring, and the sol spinning solution is obtained after 5h of incubation and stirring;

[0093] (6) the sol spinning solution is loaded into the electrospinning device, and a third electrospinning film is continuously received on the powder layer by electrospinning, and the electrospinning conditions are as follows: the inner diameter of the needle is 0.16 mm, the voltage is 18 kV, the flow rate of the sol spinning solution is 1.3 mL / h, the ambient temperature is 25°C, the humidity is 50%, and the distance from the receiving plate is 17 cm;

[0094] (7) placed in a high-temperature sintering furnace, calcined at a temperature of 1000°C for 5h, washed with dilute hydrochloric acid and then washed with water;

[0095] (8) placed in a drying oven at 60°C for drying.

[0096] A composite membrane No. 11 is obtained, which has a three-layer structure, the first layer is a solid porous iron oxide microfiltration membrane with a thickness of 60μm, the pore size is 0.1-10μm, the middle layer is an adsorbed particle with a thickness of 45μm, the particle size is 10-30μm, and the third layer is an iron oxide nanofiltration membrane with a thickness of 300μm, the pore size is 1-2nm.

[0097] The turbidity of the wastewater to be treated is 16.1°, the conductivity is 3542μS / cm, the ammonia nitrogen content is 4.33mg / L, and the COD value is 3.3mg / L. The wastewater to be treated is treated at an operating pressure of 0.6Mpa, and the treated water quality is detected, and the results are shown in Table 1:

[0098] Table 1 Water quality detection results after composite membrane treatment

[0099] SDI Turbidity (°) Conductivity (μS / cm) Desalination rate (%) Ammonia nitrogen content (mg / L) COD (mg / L) Composite membrane No. 1 2.0 0.12 1.3 98.4 3.17 2.0 Composite membrane No. 2 1.7 0.11 1.1 98.9 3.02 1.9 Composite membrane No. 3 1.6 0.11 1.0 98.6 2.94 1.9 Composite membrane No. 4 1.6 0.10 1.0 99.1 3.00 1.8 Composite membrane No. 5 1.9 0.11 1.2 98.4 3.11 2.0 Composite membrane No. 6 1.9 0.12 1.2 98.5 3.13 2.0 Composite membrane No. 7 1.8 0.10 1.0 99.0 3.01 1.8 Composite membrane No. 8 1.7 0.11 1.2 98.0 3.20 2.2 Composite membrane No. 9 1.7 0.11 1.0 99.4 2.95 1.8 Composite membrane No. 10 2.8 0.25 3.6 96.3 3.56 2.6 Composite membrane No. 11 3.2 0.28 5.8 95.2 3.77 2.7

[0100] As shown in Table 1, the composite membrane of the application has good effects on SDI, turbidity, conductivity and desalination rate of the water to be treated, and the treatment effects on ammonia nitrogen and COD are relatively general, and the content of nano calcium carbonate, the concentration of polyvinyl alcohol, the flow rate of the core layer spinning solution and the flow rate of the sol spinning solution have great influences on the treatment effect of the final water to be treated, mainly because these conditions will affect the specific surface area, porosity and the like of the membrane. The filtration effect of the composite membrane No. 10 on the wastewater is far less than that of the composite membranes No. 1-9, and at the same time, during the water treatment process, it is also observed that the pollen carbon particles on the blended jade membrane fall off.

Claims

1. A composite membrane applied to industrial wastewater treatment, characterized by, The composite membrane is a three-layer structure, the first layer is a hollow porous iron oxide microfiltration membrane with a thickness of 30-80 μm, the middle layer is an adsorption particle with a thickness of 30-60 μm, and the third layer is an iron oxide nanofiltration membrane with a thickness of 100-500 μm.

2. The composite membrane as claimed in claim 1, applied in industrial wastewater treatment, characterized in that, The hollow porous iron oxide microfiltration membrane has a pore size of 0.1-10 μm.

3. The composite membrane as claimed in claim 1, wherein the composite membrane is used in industrial wastewater treatment. The adsorption particle is a pollen carbon particle with a particle size of 10-30 μm.

4. The composite membrane as claimed in claim 1, wherein the composite membrane is used in industrial wastewater treatment. The iron oxide nanofiltration membrane has a pore size of 1-2 nm.

5. The method of claim 1-4 for the preparation of a composite membrane to be applied in the treatment of industrial wastewater, characterized by the fact that, The method comprises the following steps: 8 parts of hydrated ferric chloride are taken, 50 parts of anhydrous ethanol are added, stirred and dissolved, 6 parts of acetylacetone are added, stirred uniformly, then heated in a 50℃ water bath and 3-5 parts of epichlorohydrin are added under stirring, 1-2 parts of nano calcium carbonate particles are added after 4h of incubation and stirring, and the shell sol spinning solution is obtained after uniform stirring; Polyvinyl alcohol powder and water are mixed, heated and stirred to dissolve, and a core layer spinning solution with a polyvinyl alcohol content of 8-10wt.% is obtained; The first layer of electrospun membrane is obtained by using coaxial electrospinning method; A layer of pollen is uniformly laid on the first layer of electrospun membrane to obtain a middle pollen layer; 8 parts of hydrated ferric chloride are taken, 50 parts of anhydrous ethanol are added, stirred and dissolved, 6 parts of acetylacetone are added, stirred uniformly, then heated in a 50℃ water bath and 3-5 parts of epichlorohydrin are added under stirring, and the sol spinning solution is obtained after 5h of incubation and stirring; The sol spinning solution is loaded into an electrospinning device, and the third layer of electrospun membrane is continuously received on the pollen layer by using electrospinning method; It is placed in a high-temperature sintering furnace, calcined at a temperature of 700-1000℃ for 5-8h, washed with dilute hydrochloric acid, and then washed with water; It is placed in a drying oven at 60℃ for drying.

6. The method for preparing a composite membrane for industrial wastewater treatment according to claim 5, characterized in that, The coaxial electrospinning conditions in step (3) are as follows: two syringes are placed on two propulsion devices and connected to a coaxial needle by a polytetrafluoroethylene tube, the inner diameter of the outer needle is 0.86 mm, the outer diameter is 1.26 mm, the inner diameter of the inner needle is 0.33 mm, the outer diameter is 0.63 mm, the voltage is 15-20 kV, the shell sol spinning solution flow rate is 1.0 mL / h, the core layer spinning solution flow rate is 0.15-0.25 mL / h, the distance between the needle tip and the collector is fixed at 15 cm, the electrospinning temperature is 25℃, and the relative humidity is 50%.

7. The method for preparing a composite membrane for industrial wastewater treatment according to claim 5, characterized in that, The pollen in step (4) includes corn pollen, tea pollen, buckwheat pollen, rape pollen and dandelion pollen.

8. The method of claim 5, wherein the composite membrane is prepared by the steps of: (a) preparing a porous support layer; (b) preparing a polymer layer on the porous support layer; (c) preparing a metal layer on the polymer layer; and (d) preparing a polymer layer on the metal layer. The electrospinning conditions in step (6) are as follows: the needle inner diameter specification is 0.16 mm, the voltage is 15-20 kV, the sol spinning solution flow rate is 1.0-1.5 mL / h, the environmental temperature is 25℃, the humidity is 50%, and the distance from the needle to the receiving plate is 17 cm.