CN111330461B - Magnetic response oil-water separation membrane and preparation method and self-cleaning method thereof - Google Patents
Magnetic response oil-water separation membrane and preparation method and self-cleaning method thereof Download PDFInfo
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Abstract
The invention provides a magnetic response oil-water separation membrane, a preparation method thereof and a self-cleaning method. The oil-water separation membrane provided by the invention can realize self-cleaning of the membrane surface by utilizing the periodic transformation of an external magnetic field; meanwhile, the oil-water separation membrane provided by the invention can well prevent oil macromolecules from contacting the membrane contact channel to pollute the pore channel, so that the oil-water separation membrane can keep a certain membrane flux and has stable separation efficiency, and the oil-water separation membrane has a good application prospect.
Description
Technical Field
The invention belongs to the field of oil-water separation, relates to a magnetic response oil-water separation membrane, a preparation method and a self-cleaning method thereof, and particularly relates to a magnetic response oil-water separation membrane for separating emulsified oil from water, a preparation method and a self-cleaning method thereof.
Background
The pollution of the water body caused by the discharge of oily sewage in production and life is increasingly serious, and the sewage discharged in production and life mainly comprises oily sewage and water-containing waste oil, so that the oil-water separation has wide application requirements in social production and daily life of people.
The polymer membrane separation technology is a novel separation technology, has simple treatment process, low energy consumption and convenient automatic control, and is widely applied to the fields of drinking water purification, wastewater treatment and material separation and extraction. The most straightforward way to make a high efficiency filter medium is to use nano-sized fibers in the filter material. The electrostatic spinning technology is one of the emerging important technologies for manufacturing the nano fibers, and has the advantages of simple manufacturing equipment, convenient operation, low manufacturing cost, cheap raw materials, controllability of products, realization of industrial production and the like, thereby becoming a popular object. Compared with the traditional spinning method, the fiber prepared by the electrostatic spinning method is much thinner, the diameter is generally between tens of nanometers and hundreds of nanometers, and the spun nanofiber has the advantages of higher specific surface area, porosity, high fineness and uniformity of the fiber, large length-diameter ratio and the like. Has important application in the fields of biomedical tissue engineering materials, filter materials, catalyst carrier materials and the like.
The existing polymer membrane materials can be roughly divided into two types according to the hydrophilicity and the hydrophobicity: one is hydrophobic membrane material, and the common hydrophobic membrane is polyethylene, polyvinylidene fluoride or polytetrafluoroethylene; the hydrophobic membrane has high mechanical strength, is slightly influenced by a surfactant, has low energy consumption relative to a hydrophilic membrane, has higher initial flux, is beneficial to oil-water separation, but cannot form a hydration layer which effectively prevents oil drops from reaching the surface of the membrane on the surface of the membrane due to the poor hydrophilic ability of the hydrophobic membrane material, so that a great amount of oil drops and other impurities are adsorbed on the surface of the membrane, the membrane is seriously polluted, the flux attenuation is fast, and the membrane is difficult to clean. The other is hydrophilic membrane material, such as cellulose and its various derivatives, polyvinyl alcohol, etc., while good hydrophilicity is beneficial to reducing membrane pollution in the operation process, on the other hand, the hydrophilicity is too high, the membrane is easy to dissolve, and the mutual diffusion between solvent and non-solvent in the phase inversion process can be reduced in the membrane forming process, so that the membrane skin layer is too thick, the porosity is low, the flux is extremely low, and the membrane is not suitable for practical industrial application.
Meanwhile, in the process of separating oil from water, the traditional oil-water separation membrane can generate membrane pollution phenomena of different degrees, membrane flux can be reduced, the efficiency of oil-water separation is reduced, and the cost of membrane separation is increased. The magnetic particles are grafted to the polymer membrane for the oil-water separation process, so that the pollution resistance of the membrane can be effectively realized. CN108840400A discloses a magnetic oil-water separation membrane, which is prepared by using a waste solvent induced phase separation foaming technique and a two-step method to prepare a polyimide composite microporous membrane through surface silanization. CN110424099A discloses a multi-stage composite nanofiber membrane for oil-water separation and a preparation method thereof, wherein the preparation method comprises the steps of dissolving a polymer in a solvent to obtain a spinning solution; carrying out electrostatic spinning on the spinning solution to obtain a polymer nanofiber membrane; carrying out modification treatment on the polymer nanofiber membrane to obtain a modified nanofiber membrane, wherein the modification treatment is acid treatment or alkali treatment; the modified nanofiber membrane is soaked in a phytic acid solution for a period of time, then a metal ion solution is added, and after the modified nanofiber membrane is continuously soaked for a period of time, the multi-stage composite nanofiber membrane is obtained.
Therefore, it is necessary to develop an oil-water separation membrane that can not only realize the high-efficiency separation of oil and water, but also achieve a certain contamination resistance to meet the application requirements.
Disclosure of Invention
The invention aims to provide a magnetic response oil-water separation membrane, a preparation method and a self-cleaning method thereof, and the oil-water separation membrane provided by the invention can realize self-cleaning of the surface of the membrane by utilizing periodic transformation of an external magnetic field; meanwhile, the oil-water separation membrane provided by the invention can well prevent oil macromolecules from contacting the membrane contact channel to pollute the pore channel, so that the oil-water separation membrane can keep a certain membrane flux and has stable separation efficiency, and the oil-water separation membrane has a good application prospect.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the invention provides a magnetic-response oil-water separation membrane, which comprises a base membrane and magnetic composite nanoparticles chemically grafted on the surface of the base membrane.
According to the invention, the magnetic composite nano particles are chemically grafted on the base film, so that the phenomenon of film pollution can be improved, and further, if an external magnetic field which is constantly changed is applied, the dropping of pollutants on the surface of the film can be promoted through the back-and-forth swing of the magnetic composite nano particles on the surface of the oil-water separation film, so that the self-cleaning of the surface of the film is realized. Meanwhile, the magnetic particles grafted on the surface of the base membrane can better prevent oil macromolecules from contacting the base membrane to cause pore pollution, so that the oil-water separation membrane provided by the invention can keep stable and higher membrane flux and stable separation efficiency, and has good application prospect in the field of oil-water separation.
Preferably, the magnetic composite nanoparticles are polymer-coated magnetic nanoparticle materials.
Preferably, the magnetic nanoparticle material is selected from Fe2O3、Fe3O4Or MeFe2O4Any one or a combination of at least two of them, wherein Me is selected from Co, Mn or Ni.
Preferably, the magnetic nanoparticle material has an average particle size selected from 20 to 500nm, such as 30nm, 50nm, 80nm, 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, and the like.
In the application, the magnetic nanoparticles are coated, so that the magnetic nanoparticles can be stably fixed on the base film, the situation that the application effect is poor due to the fact that the magnetic particles are separated from the base film in the using process is avoided, the coating layer has a good protection effect on the magnetic nanoparticles, the magnetic particles can be prevented from being oxidized or polluted, and the service life of the oil-water separation membrane provided by the invention is prolonged.
Preferably, the material of the base film is selected from any one or a combination of at least two of polyacrylonitrile, polyvinyl alcohol, polymethyl methacrylate, polypyrrolidone, polyimide, polylactic acid, polyaniline, cellulose acetate, polyvinylpyrrolidone, chitosan, polysulfone, polyethersulfone, polysulfone amide, or sulfonated polysulfone.
Preferably, the content of the magnetic composite nano-particles is 0.5-10%, such as 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, etc., based on 100% of the total mass of the magnetic-responsive oil-water separation membrane.
In a second aspect, the present invention provides a method for preparing a magnetic-response oil-water separation membrane according to the first aspect, the method comprising the steps of:
and carrying out chemical grafting reaction on the modified base membrane and the magnetic composite nano particles to obtain the magnetic response oil-water separation membrane.
Preferably, the modifier of the base film comprises any one of sodium hydroxide, hydrochloric acid, sulfonic acid, thionyl chloride, dopamine, hydroxylamine hydrochloride or a combination of at least two of silane coupling agents.
Preferably, the modification method of the base film includes any one or a combination of at least two of heating, soaking, or surface coating.
Preferably, the base membrane is an electrospun membrane.
The modification of the base film can be carried out in a mode of once or more than twice, the same reactant or different reactants can be selected for each modification, and the time for each modification is preferably 5-300min, such as 30min, 50min, 80min, 100min, 120min, 150min, 180min, 200min, 220min, 250min, 270min and the like.
The electrostatic spinning membrane is preferably selected as the base membrane, is a common electrostatic spinning membrane in the prior art, has high porosity and uniform fiber diameter, and is suitable for large-scale production. Can be prepared by a conventional method or purchased; furthermore, the electrostatic spinning membrane can be directly applied and can also be subjected to hot pressing treatment to improve the mechanical property of the electrostatic spinning membrane; an exemplary preparation method of the polyacrylonitrile membrane is as follows:
polyacrylonitrile powder (shanghai xu major biotechnology limited, molecular weight 15 ten thousand) was dissolved in dimethylformamide to obtain 15 wt% of spinning solution, and the primary product was prepared by electrospinning, wherein the voltage was 15KV and the distance was 10 cm.
And then carrying out hot pressing on the polyacrylonitrile nano-fiber membrane, wherein the hot pressing temperature is 280 ℃ and the time is 20s, so as to obtain the polyacrylonitrile nano-fiber membrane.
An exemplary list of polyacrylonitrile/polymethylmethacrylate membranes is prepared:
polyacrylonitrile powder/polymethylmethacrylate powder (purchased from shanghai xu major biotechnology limited, molecular weights of 15 ten thousand and 10 ten thousand, respectively) was dissolved in dimethylformamide at a ratio of 9:1 to prepare 15 wt%, and a preliminary product was prepared by electrospinning, wherein the voltage was 18KV and the distance was 12cm, to obtain a polyacrylonitrile nanofiber membrane.
In the present invention, the magnetic composite nanoparticle has a carboxyl group and/or an amine group.
Preferably, the average particle size of the magnetic composite nanoparticles is 200-300nm, such as 220nm, 240nm, 260nm, 280nm, 290nm, and the like.
Preferably, the preparation method of the magnetic composite nanoparticle comprises the following steps:
and (3) coating and modifying the magnetic nano-particle material by utilizing organic amine and/or organic acid.
Preferably, the organic amine is selected from any one of dopamine, silane coupling agent, hexadecyl trimethyl ammonium bromide, polyethyleneimine or diethylene triamine or a combination of at least two of the dopamine, the silane coupling agent, the hexadecyl trimethyl ammonium bromide, the polyethyleneimine and the diethylene triamine.
Preferably, the organic acid is selected from any one of or a combination of at least two of oleic acid, lauric acid, citric acid, dodecylbenzene sulfonic acid, dimercaptosuccinic acid, ethylene diamine tetraacetic acid or acrylic acid.
The method can coat the magnetic nanoparticles once or more than twice, the same reactant or different reactants can be selected for each coating, and the time for each coating is preferably 5-300min, such as 30min, 50min, 80min, 100min, 120min, 150min, 180min, 200min, 220min, 250min, 270min and the like.
Preferably, the grafting reaction is carried out in solution.
Similarly, the grafting reaction can be carried out by one or more times of grafting, and the time of each grafting is preferably 5-300min, such as 30min, 50min, 80min, 100min, 120min, 150min, 180min, 200min, 220min, 250min, 270min, etc.
All the reaction temperatures, including modification, coating, grafting, etc., are independently selected from 0-120 deg.C, such as 10 deg.C, 20 deg.C, 30 deg.C, 50 deg.C, 70 deg.C, 80 deg.C, 100 deg.C, 110 deg.C, etc.
In a third aspect, the present invention provides a self-cleaning method for a magnetic-responsive oil-water separation membrane according to the first aspect, the self-cleaning method comprising: after the magnetic response oil-water separation membrane is used, an external magnetic field is applied to realize self-cleaning of the magnetic response oil-water separation membrane.
Preferably, the variation frequency of the applied magnetic field is 10 to 100Hz, such as 20Hz, 30Hz, 40Hz, 50Hz, 60Hz, 70Hz, 80Hz, 90Hz, etc., and the magnetic field strength is 20 to 200T, such as 40T, 50T, 60T, 80T, 100T, 120T, 150T, 180T, etc.
Compared with the prior art, the invention has the following beneficial effects:
(1) according to the invention, the magnetic composite nano particles are chemically grafted on the base membrane, so that the phenomenon of membrane pollution can be improved by the magnetic particles;
(2) if an external magnetic field which changes constantly is applied to the oil-water separation membrane, the oil-water separation membrane can promote the shedding of pollutants on the surface of the membrane through the back-and-forth swing of the magnetic composite nano particles on the surface of the oil-water separation membrane, so that the self-cleaning of the surface of the membrane is realized;
(3) the magnetic particles grafted on the surface of the base membrane can better prevent oil macromolecules from contacting the base membrane to cause pore pollution, so that the oil-water separation membrane provided by the invention can keep stable and higher membrane flux and stable separation efficiency, and has good application prospect in the field of oil-water separation;
(4) the oil-water separation membrane provided by the invention has good oil-water separation effect, high pollution resistance and long service life, wherein the oil-water separation effect is more than 95%, and the recovery rate of the membrane flux after magnetic response cleaning is more than 95%.
Detailed Description
The technical solution of the present invention is further explained by the following embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.
The materials and the reference information of the examples and comparative examples are as follows:
example 1
A magnetic response oil-water separation membrane is prepared by the following steps:
(1) preparation of magnetic composite nanoparticles
Dissolving 8.2g of sodium acetate and 2.7g of ferric chloride in 120mL of ethylene glycol at the same time, uniformly stirring, and placing the mixture in a hydrothermal reaction kettle for heating and heat preservation at 200 ℃ for 10 hours to obtain ferroferric oxide magnetic particles with the average particle size of 300 nm;
preparing 2mg/mL dopamine TRIS solution, soaking the magnetic nanoparticles in the solution, and reacting at normal temperature for 24h to obtain magnetic composite nanoparticles;
(2) modifying the base film
Sequentially carrying out modification on the polyacrylonitrile membrane for 40min at room temperature and with the concentration of sodium hydroxide of 1 mol/L; the concentration of hydrochloric acid is 0.1mol/L, the room temperature and the modification time are 40min, and 2g of thionyl chloride steam (100 ℃) is treated for 20min to obtain a modified basement membrane;
(3) preparation of magnetic response oil-water separation membrane
And soaking the modified base membrane in pure ethanol solution of the magnetic composite nano particles for 2 hours to obtain the magnetic response oil-water separation membrane, wherein the mass ratio of the magnetic particles to the base membrane is 5%.
Example 2
A magnetic response oil-water separation membrane is prepared by the following steps:
(1) preparation of magnetic composite nanoparticles
Dissolving 2g of ferrous chloride and 5g of ferric chloride in secondary distilled water at the same time, dropwise adding sodium hydroxide under the protection of nitrogen, violently stirring, and reacting for 60min to obtain ferroferric oxide magnetic particles with the average particle size of 500 nm;
preparing 2mg/mL dopamine TRIS solution, soaking the magnetic nanoparticles in the solution, reacting for 24 hours at normal temperature, then preparing 0.5% gamma-aminopropyltriethoxysilane ethanol aqueous solution, soaking the dopamine-modified magnetic nanoparticles in the solution for 24 hours at normal temperature to obtain magnetic composite nanoparticles;
(2) modifying the base film
Sequentially carrying out modification on the polyacrylonitrile/polymethyl methacrylate membrane for 40min at room temperature and with the sodium hydroxide concentration of 1 mol/L; the concentration of hydrochloric acid is 0.1mol/L, the room temperature and the modification time are 40min, and 3g of thionyl chloride steam (100 ℃) is treated for 20min to obtain a modified basement membrane;
(3) preparation of magnetic response oil-water separation membrane
A magnetic-response oil-water separation membrane was obtained in the same manner as in example 1.
Example 3
A magnetic response oil-water separation membrane is prepared by the following steps:
(1) preparation of magnetic composite nanoparticles
Referring to example 1, ferroferric oxide magnetic particles with the average particle size of 20nm are prepared;
preparing an ethanol solution of oleic acid with the concentration of 20%, soaking the magnetic nanoparticles in the ethanol solution, and reacting at normal temperature for 12 hours to obtain magnetic composite nanoparticles;
(2) modifying the base film
Preparing a 3mg/mL dopamine TRIS solution, soaking a polyimide film in the solution, and reacting at normal temperature for 12 hours to obtain a modified basement membrane;
(3) preparation of magnetic response oil-water separation membrane
And soaking the modified polyamide membrane in a 75% ethanol solution of 20% magnetic composite nanoparticles, adding 1g of carbodiimide, and treating for 2h to obtain the magnetic response oil-water separation membrane.
Example 4
A magnetic response oil-water separation membrane is prepared by the following steps:
(1) preparation of magnetic composite nanoparticles
Referring to example 3, oleic acid-coated magnetic nanoparticles were prepared, wherein the magnetic nanoparticles were iron sesquioxide magnetic particles having an average particle diameter of 20 nm;
(2) modifying the base film
Preparing a 3mg/mL dopamine TRIS solution, soaking a polyvinylpyrrolidone membrane in the solution, and reacting at normal temperature for 12h to obtain a modified basement membrane;
(3) preparation of magnetic response oil-water separation membrane
Referring to example 3, a magnetic-responsive oil-water separation membrane was obtained.
Example 5
A magnetic response oil-water separation membrane is prepared by the following steps:
(1) magnetic composite nanoparticles
Aminated ferromagnetic sesquioxide nanoparticles (APTS @ Fe)2O3) Purchased from Zhongkeleiming (Beijing) science and technology Ltd, electron microscope size (Fe)2O3Core diameter) of about 10nm, hydrodynamic size (Fe)2O3Core surface hydration layer diameter) of about 82nm and zeta potential (particle surface potential) of about 61 mV.
(2) Modifying the base film
Sequentially carrying out modification on the polyacrylonitrile membrane for 40min at room temperature and with the concentration of sodium hydroxide of 1 mol/L; the concentration of hydrochloric acid is 0.1mol/L, the room temperature and the modification time are 40min, and 2g of thionyl chloride steam (100 ℃) is treated for 20min to obtain a modified basement membrane;
(3) preparation of magnetic response oil-water separation membrane
Referring to example 1, a magnetic-responsive oil-water separation membrane was obtained.
Example 6
A magnetic response oil-water separation membrane is prepared by the following steps:
(1) commercially available magnetic composite nanoparticles
The dimercaptosuccinic acid-coated ferric oxide is purchased from the science and technology Limited company of Zhongkoraiming (Beijing) under the model DMSA @ Fe2O3Electron microscope size (Fe)2O3Core diameter) about 10 nm; hydrodynamic size (Fe)2O3Core + surface coating + surface hydration layer diameter) of about 78.6nm, zeta potential (particle surface potential) -70 mV;
(2) modifying the base film
Preparing a 3mg/mL dopamine TRIS solution, adding HD-M8173 secondary aminosilane, purchasing the solution in Hengda Zhongcheng, preparing the solution into a dilute solution with the concentration of 0.1% by using ethanol, soaking a polysulfonamide membrane in the solution, and reacting at normal temperature for 2 hours to obtain a modified basement membrane;
(3) preparation of magnetic response oil-water separation membrane
Preparing an ethanol solution of 20% solution of magnetic composite nano particles, soaking the modified base membrane in the ethanol solution, heating to 50 ℃, and reacting for 2 hours to obtain the magnetic response oil-water separation membrane.
Example 7
A magnetic response oil-water separation membrane is prepared by the following steps:
(1) commercially available magnetic composite nanoparticles
Polyethylene glycol 2000 modified magnetic Fe3O4The nanoparticles were purchased from Zhongkeleiming (Beijing) science and technology Co., Ltd, type PEG ferroferric oxide magnetic nanoparticles, Fe3O4The electron microscope size of the nano-particles is about 10nm, the hydrodynamic size (the diameter of the inner core + the coating layer + the surface hydration layer) is about 25nm, the zeta potential (the surface potential of the particles) is 35mV, and the saturation magnetization is about 80 emu/g.
(2) Modifying the base film
Sequentially carrying out modification on the polyacrylonitrile membrane for 40min at room temperature and with the concentration of sodium hydroxide of 1 mol/L; the concentration of hydrochloric acid is 0.1mol/L, the room temperature and the modification time are 40min, and 2g of thionyl chloride steam (100 ℃) is treated for 20min to obtain a modified basement membrane;
(3) preparation of magnetic response oil-water separation membrane
Referring to example 1, a magnetic-responsive oil-water separation membrane was obtained.
Example 8
A magnetic response oil-water separation membrane is prepared by the following steps:
(1) commercially available magnetic composite nanoparticles
The carboxylated ferroferric oxide magnetic nanoparticles are purchased from the science and technology limited company of Zhongkorei (Beijing), and the technical parameters are as follows: electron microscope size (Fe)3O4Core diameter) of about 7nm, hydrodynamic size (Fe)3O4Core + surface coating + surface hydration layer diameter) of about 30nm and zeta potential (particle surface potential) of about-43 mV.
(2) Modifying the base film
Preparing a 3mg/mL dopamine TRIS solution, adding a gamma-aminopropyltriethoxysilane coupling agent, purchasing the solution in Hengda Zhongcheng, preparing a dilute solution with 0.1% concentration by using ethanol, soaking a polysulfonamide membrane in the dilute solution, and reacting at normal temperature for 2 hours to obtain a modified basement membrane;
(3) preparation of magnetic response oil-water separation membrane
Referring to example 6, a magnetic-responsive oil-water separation membrane was obtained.
Example 9
A magnetic response oil-water separation membrane is prepared by the following steps:
(1) preparation of magnetic composite nanoparticles
Preparing gamma-ferric oxide nano particles by a coprecipitation method: under nitrogen atmosphere, a solution with a molar ratio of Fe (III)/Fe (II) of 2:1 is prepared, and 12.5% of N (CH) is slowly added3)4Adjusting the pH value of an OH solution to 13, fully stirring for 60min to obtain magnetic ferroferric oxide, carrying out magnetic separation, immediately washing with distilled water, stabilizing in deionized water, adjusting the pH value to 3.0, carrying out ventilation oxidation at 95 ℃ to synthesize stable gamma-ferric oxide nanoparticles, preparing 10mg/mL dimethyl sulfoxide solution of DMSA, soaking the gamma-ferric oxide nanoparticles in the solution, and reacting for 12 h;
(2) modifying the base film
Sequentially carrying out modification on the polyacrylonitrile membrane for 40min at room temperature and with the concentration of sodium hydroxide of 1 mol/L; the concentration of hydrochloric acid is 0.1mol/L, the room temperature and the modification time are 40min, and 2g of thionyl chloride steam (100 ℃) is treated for 20min to obtain a modified basement membrane;
(3) preparation of magnetic response oil-water separation membrane
Referring to example 1, a magnetic-responsive oil-water separation membrane was obtained.
Comparative examples 1 to 9
The difference from examples 1 to 9 is that, in comparative examples 1 to 9, steps (2) to (3) were performed without adding the magnetic composite nanoparticles (step (1) was omitted).
Comparative example 10
Under nitrogen atmosphere, a solution with a molar ratio of Fe (III)/Fe (II) of 2:1 is prepared, and 12.5% of N (CH) is slowly added3)4Adjusting the pH value of an OH solution to 13, fully stirring for 60min to obtain magnetic ferroferric oxide, dispersing the magnetic ferroferric oxide in 400mL of ethanol and water (V/V is 1:1) solution, carrying out ultrasonic treatment at room temperature for 30min, drying the magnetic ferroferric oxide in a vacuum drying oven at 60 ℃, dispersing 1g of ferroferric oxide nano particles in 100mL of N, N-Dimethylformamide (DMF) solvent, carrying out ultrasonic treatment for 30min, and preparing the DM of polyacrylonitrile with the mass fraction of 15%And F, mixing the solution and the solution, and spinning.
Comparative example 11
A magnetic response oil-water separation membrane is prepared by the following steps:
(1) preparation of magnetic composite nanoparticles
Dissolving 8.2g of sodium acetate and 2.7g of ferric chloride in 120mL of ethylene glycol at the same time, uniformly stirring, and placing the mixture in a hydrothermal reaction kettle for heating and heat preservation at 200 ℃ for 10 hours to obtain ferroferric oxide magnetic particles with the average particle size of 300 nm;
(2) modifying the base film
Sequentially carrying out modification on the polyacrylonitrile membrane for 40min at room temperature and with the concentration of sodium hydroxide of 1 mol/L; the concentration of hydrochloric acid is 0.1mol/L, the room temperature and the modification time are 40min, and 2g of thionyl chloride steam (100 ℃) is treated for 20min to obtain a modified basement membrane;
(3) preparation of magnetic response oil-water separation membrane
And soaking the modified base membrane in an ethanol solution of the magnetic nanoparticles for 2 hours to obtain the oil-water separation membrane.
Performance testing
The oil-water separation base films provided in examples 1 to 9 and comparative examples 1 to 11 were subjected to a performance test by the following method:
(1) oil-water separation effect:
separating two different oil and water emulsions using a sample, wherein:
the test sample A is a cyclohexane/water emulsion which is stable without a surfactant, the volume ratio of cyclohexane to water is 1:9, and the particle size of an emulsion is 2-10 mu m;
the test sample B is a cyclohexane/water solution stabilized by 1 wt% of sodium dodecyl benzene sulfonate surfactant, the volume ratio of cyclohexane to water is 1:9, and the particle size of the emulsion is 2-10 mu m;
and (3) filtering pressure: 0.02 MPa.
(2) Self-cleaning effect: after filtration of the test (1), applying an alternating magnetic field for 30min as shown in table 1; the percentage of permeation flux was measured for test sample a and test sample B before and after application of the alternating magnetic field (the permeation flux of the membrane measured in the respective first oil-water separation experiments was 100%).
The test results are shown in table 1:
TABLE 1
The embodiment and the performance test show that the oil-water separation membrane provided by the invention has good oil-water separation effect, high pollution resistance and long service life, wherein the oil-water separation efficiency of an oil-water mixture is over 95 percent, the oil-water separation efficiency of an emulsified oil-water mixture is over 95 percent, and the recovery rate of permeation flux of the membrane is over 95 percent after the membrane is self-cleaned by applying an alternating electric field.
As can be seen from the comparison of examples 1 to 9 with comparative examples 1 to 9, if the magnetic composite nanoparticles are not grafted, membrane contamination is caused by filtration; as is clear from comparison between example 1 and comparative examples 10 to 11, the object of self-cleaning can be achieved only by using the oil-water separation membrane provided by the present invention.
The applicant states that the magnetic response oil-water separation membrane, the preparation method thereof and the self-cleaning method thereof are illustrated by the above examples, but the invention is not limited to the above detailed method, i.e. the invention is not meant to be implemented by relying on the above detailed method. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.
Claims (15)
1. A self-cleaning method of a magnetic-response oil-water separation membrane, characterized by comprising: after the magnetic response oil-water separation membrane is used, an external magnetic field is applied to realize self-cleaning of the magnetic response oil-water separation membrane;
the magnetic response oil-water separation membrane comprises a base membrane and magnetic composite nano particles chemically grafted on the surface of the base membrane;
the magnetic response oil-water separation membrane is prepared by adopting the following method, and the method comprises the following steps: carrying out chemical grafting reaction on the modified base membrane and the magnetic composite nano particles to obtain the magnetic response oil-water separation membrane;
the variation frequency of the external magnetic field is 10-100 Hz, and the magnetic field intensity is 20-200T.
2. The self-cleaning method of claim 1, wherein the magnetic composite nanoparticles are polymer-coated magnetic nanoparticle materials.
3. Self-cleaning method according to claim 2, wherein the magnetic nanoparticle material is selected from Fe2O3、Fe3O4Or MeFe2O4Any one or a combination of at least two of them, wherein Me is selected from Co, Mn or Ni.
4. The self-cleaning method of claim 2, wherein the magnetic nanoparticle material has an average particle size selected from the group consisting of 20-500 nm.
5. Self-cleaning method according to claim 1, wherein the material of the base membrane is selected from any one or a combination of at least two of polyacrylonitrile, polyvinyl alcohol, polymethyl methacrylate, polypyrrolidone, polyimide, polylactic acid, polyaniline, cellulose acetate, polyvinylpyrrolidone, chitosan, polysulfone, polyethersulfone, polysulfonamide or sulfonated polysulfone.
6. The self-cleaning method of claim 1, wherein the content of the magnetic composite nano-particles is 0.5-10% based on 100% of the total mass of the magnetic-responsive oil-water separation membrane.
7. The self-cleaning method of claim 1, wherein the modifying agent of the base film comprises any one of sodium hydroxide, hydrochloric acid, sulfonic acid, thionyl chloride, dopamine, hydroxylamine hydrochloride or a combination of at least two of silane coupling agents.
8. A self-cleaning method according to claim 1, wherein the modification method of the base film comprises any one or a combination of at least two of heating, soaking or surface coating.
9. Self-cleaning method according to claim 1, wherein the base film is an electrospun film.
10. Self-cleaning method according to claim 1, wherein the magnetic composite nanoparticles carry carboxyl and/or amine groups.
11. The self-cleaning method of claim 1, wherein the average particle size of the magnetic composite nanoparticles is 200-300 nm.
12. A self-cleaning method as claimed in claim 1, wherein the method of preparing the magnetic composite nanoparticles comprises the steps of:
and (3) coating and modifying the magnetic nano-particle material by utilizing organic amine and/or organic acid.
13. Self-cleaning method according to claim 12, wherein said organic amine is selected from any one or a combination of at least two of dopamine, cetyltrimethyl ammonium bromide, polyethyleneimine or diethylenetriamine.
14. The self-cleaning method of claim 12, wherein the organic acid is selected from any one of or a combination of at least two of oleic acid, lauric acid, citric acid, dodecylbenzene sulfonic acid, dimercaptosuccinic acid, ethylene diamine tetraacetic acid, or acrylic acid.
15. Self-cleaning method according to claim 1, wherein the grafting reaction is performed in solution.
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