Magnetic multi-effect amphiphilic particles, methods of making and using the same

Abstract

The application relates to the technical field of sewage treatment, and provides a magnetic multi-effect amphiphilic particle as well as a preparation method and application thereof. The magnetic multi-effect amphiphilic particle comprises a core-shell separated magnetic Fe3O4 particle inner core and a silica shell layer, the outer surface of the silica shell layer comprises a hydrophilic part and a hydrophobic part, the inner surface of the silica shell layer and the surface of the magnetic Fe3O4 particle inner core are grafted with poly (dimethylaminoethyl methacrylate), and the silica shell layer has a micro-pore structure. The magnetic multi-effect amphiphilic particle provided by the application has a wide size distribution window, can realize sub-micron / micron distribution, and has uniform particle size; has excellent emulsifying performance; the liquid drops emulsified by the magnetic multi-effect amphiphilic particle can be controlled by an external magnetic field, oil drops can be enriched and migrated, and thus oil-water separation can be realized; and the magnetic multi-effect amphiphilic particle also has selective adsorption performance, can selectively adsorb partially hydrolyzed polyacrylamide, and can efficiently treat oil-containing sewage containing partially hydrolyzed polyacrylamide in one step.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and more specifically, to a magnetic multifunctional amphiphilic particle, its preparation method, and its application. Background Technology

[0002] Partially hydrolyzed polyacrylamide (PPA) is a water-soluble polymer with excellent flocculation, thickening, and drag-reducing properties, and has been widely used in oilfield recovery, especially in tertiary oil recovery, to improve oilfield recovery rates. However, the treatment of oily wastewater containing PPA from PPA recovery is more difficult than that of ordinary oily wastewater. Existing treatment methods generally require multiple steps to achieve the required standards for treating oily wastewater containing PPA. How to efficiently remove PPA while achieving oil-water separation in one step has always been a challenge in the treatment of oily wastewater containing PPA.

[0003] Amphiphilic solid particulate emulsifiers possess excellent emulsifying capabilities, achieving emulsification by reducing the interfacial tension between two phases. They exhibit high interfacial desorption energy, enabling efficient and stable emulsification of emulsions. If the amphiphilic solid particles are magnetic, the emulsified droplets will also be magnetic, allowing for manipulation of the dispersed phase droplets. Based on this, magnetic amphiphilic solid particles can be used to treat oily wastewater, emulsifying the oil phase in the water, thereby stabilizing the dispersed oil droplets. Under the control of an external magnetic field, the oil droplets migrate and accumulate, ultimately achieving oil-water separation. However, while existing amphiphilic solid particulate emulsifiers can successfully achieve oil-water separation when used to treat partially hydrolyzed polyacrylamide-containing oily wastewater, they cannot simultaneously and efficiently remove the partially hydrolyzed polyacrylamide in one step. Summary of the Invention

[0004] The purpose of this invention is to provide a magnetic multifunctional amphiphilic particle and its preparation method, so as to solve the technical problem that it is difficult to treat oily wastewater containing partially hydrolyzed polyacrylamide to meet standards in one step in the prior art.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] In a first aspect, the present invention provides a magnetic multifunctional amphiphilic particle, the magnetic multifunctional amphiphilic particle comprising a core-shell separated magnetic Fe3O4 particle core and a silica shell, the outer surface of the silica shell comprising a hydrophilic portion and a hydrophobic portion, the inner surface of the silica shell and the surface of the magnetic Fe3O4 particle core being grafted with poly(diethylaminoethyl methacrylate) (PDEAEMA), and the silica shell having a microporous structure.

[0007] It should be noted that the "micropore structure" described in this invention includes intermolecular voids in the silica macromolecular framework and defects generated during the core-shell separation process between the silica shell and the magnetic Fe3O4 particle core, and even micropores and capillaries with a pore size of 0.5 to 50 nm.

[0008] The magnetic multifunctional amphiphilic particles provided by this invention have a silicon dioxide shell coating on the core of the magnetic Fe3O4 particles, which can protect the core of the magnetic Fe3O4 particles and resist corrosion of the core of the magnetic Fe3O4 particles by hydrochloric acid, sulfuric acid, nitric acid and other substances for a certain period of time, thus ensuring the industrial application of the magnetic multifunctional amphiphilic particles.

[0009] The magnetic multifunctional amphiphilic particles provided by this invention have a silica shell outer surface that includes both hydrophilic and hydrophobic portions, giving them amphiphilic properties. Compared with traditional homogeneous particles, they have more stable emulsification characteristics and can more stably and extensively emulsify oil and water phases to form stable oil-in-water emulsions, providing a stable basis for the manipulation of emulsion droplets.

[0010] Furthermore, the functional groups on the outer surface of the silica shell of the magnetic multifunctional amphiphilic particles provided by this invention have electrostatic interactions with partially hydrolyzed polyacrylamide, promoting the adsorption of partially hydrolyzed polyacrylamide on the outer surface of the silica shell. Simultaneously, after adsorption, the wetting effect of the internal structure of the amphiphilic particles on the partially hydrolyzed polyacrylamide adsorbed on the outer surface of the silica shell promotes the adsorption process of partially hydrolyzed polyacrylamide into the silica shell. The PDEAEMA grafted onto the inner surface of the silica shell and the core surface of the magnetic Fe3O4 particles forms a brush-like coating, increasing the specific surface area and enhancing the hydrogen bond density. The microporous structure on the silica shell provides channels for the migration and transport of partially hydrolyzed polyacrylamide, thereby achieving the adsorption and migration capture of partially hydrolyzed polyacrylamide by PDEAEMA. The magnetic multifunctional amphiphilic particles provided by this invention, through the combination of internal and external structures, greatly improve the adsorption capacity and efficiency for partially hydrolyzed polyacrylamide.

[0011] Furthermore, PDEAEMA exhibits pH sensitivity, displaying hydrophilic properties at lower pH levels and hydrophobic properties at higher pH levels. This pH sensitivity allows for repeated adsorption and desorption of partially hydrolyzed polyacrylamide by PDEAEMA, enabling the reuse of these magnetically multifunctional amphiphilic particles and significantly reducing material costs in wastewater treatment. Moreover, the weakly acidic nature of partially hydrolyzed polyacrylamide further facilitates the transfer and adsorption of PDEAEMA from the silica shell surface to the interior of the silica shell.

[0012] Alternatively, using a benign solvent (such as ethanol) that partially hydrolyzes polyacrylamide to wash and extract the used magnetic multifunctional amphiphilic particles can also remove the adsorbed partially hydrolyzed polyacrylamide, enabling the reuse of the magnetic multifunctional amphiphilic particles.

[0013] According to some embodiments of the present invention, the hydrophilic portion is obtained by modifying the outer surface of the silica shell with an amino-containing silane coupling agent.

[0014] According to some embodiments of the present invention, the amino-containing silane coupling agent includes 3-aminopropyltriethoxysilane.

[0015] Modification with 3-aminopropyltriethoxysilane introduces amino groups into the hydrophilic portion of the silica shell, which can weakly interact with partially hydrolyzed polyacrylamide containing carboxyl groups, thereby achieving the adsorption of partially hydrolyzed polyacrylamide.

[0016] According to some embodiments of the present invention, the hydrophobic portion is obtained by modifying the outer surface of the silica shell with an alkyl-containing silane coupling agent.

[0017] According to some embodiments of the present invention, the alkyl-containing silane coupling agent includes n-octyltriethoxysilane.

[0018] According to some embodiments of the present invention, the hydrophilic portion accounts for 1 / 3 to 2 / 3 of the total surface area of ​​the magnetic multifunctional amphiphilic particles.

[0019] According to some embodiments of the present invention, the particle size of the magnetic multifunctional amphiphilic particles is 100nm < r ≤ 1000nm.

[0020] Secondly, the present invention provides a method for preparing magnetic multifunctional amphiphilic particles, comprising:

[0021] S1. Magnetic Fe3O4 particles and tetraethyl orthosilicate are dispersed in an alcohol solvent to obtain silicon-coated iron magnetic particles;

[0022] S2. Disperse silicon-coated ferromagnetic particles in water, add paraffin wax, heat until the paraffin wax is completely melted, stir and mix, cool and filter to obtain paraffin spheres formed by silicon-coated ferromagnetic particles embedded on the surface of paraffin wax.

[0023] S3. Disperse paraffin balls in dimethyl sulfoxide, add an amino-containing silane coupling agent, stir to react, and redisperse the obtained solid particles in an alcohol solvent to obtain hydrophilic modified particles;

[0024] S4. Disperse the hydrophilic modified particles in an alcohol solvent, add an alkyl-containing silane coupling agent, stir the reaction, and obtain amphiphilic modified particles;

[0025] S5. Mix the amphiphilic modified particles with acetic acid for 8-12 hours to obtain core-shell separated amphiphilic modified particles;

[0026] S6. The core-shell separated amphiphilic modified particles are dispersed in an alcohol solvent, and 4-(chloromethyl)phenyltrimethoxysilane is added to undergo a modification reaction; then a grafting reaction is carried out with diethylaminoethyl methacrylate (DEAEMA), and the magnetic multifunctional amphiphilic particles are obtained after the reaction is completed.

[0027] The method for preparing magnetic multifunctional amphiphilic particles provided by this invention includes a process of silica shell coating, hydrophilic modification, hydrophobic modification, acid etching treatment, 4-(chloromethyl)phenyltrimethoxysilane modification, and grafting reaction with diethylaminoethyl methacrylate (DEAEMA). Specifically, magnetic Fe3O4 particles are used as a carrier, and tetraethyl orthosilicate is used to hydrolyze the surface of the magnetic Fe3O4 particles, thereby coating the magnetic Fe3O4 particles through a sol-gel process to form a silicon-coated iron core-shell structure. Paraffin wax is then used as the oil phase, and the silicon-coated iron magnetic particles are used as solid particle emulsifiers to emulsify the oil and water phases at a temperature higher than the phase transition temperature of paraffin wax, forming a stable water-in-paraffin wax emulsion. After the emulsion cools, the paraffin wax phase solidifies and separates from the water phase, resulting in paraffin wax spheres formed by the silicon-coated iron magnetic particles embedded in the surface of the paraffin wax. The silicon-coated iron magnetic particles are partially embedded in the paraffin wax and partially exposed outside the paraffin wax. Then, the outer surface of the silicon-coated ferromagnetic particles exposed outside the paraffin wax was hydrophilically modified; the paraffin wax was then removed to expose the portion of the silicon-coated ferromagnetic particles previously protected by paraffin wax, and the outer surface of this portion was hydrophobically modified to obtain amphiphilic particles with both hydrophilic and hydrophobic portions on the particle surface. Acid etching was then performed to reduce the size of the magnetic Fe3O4 particles, causing separation from the silica shell and creating a hollow structure between the core and shell. Further modification with benzyl chloride [4-(chloromethyl)phenyl] was achieved on the surface of the magnetic Fe3O4 particles and the inner surface of the silica shell using 4-(chloromethyl)phenyltrimethoxysilane. Benzyl chloride has high reactivity and can be grafted with poly(diethylaminoethyl methacrylate) (PDEAEMA) via ATRP (atom transfer radical polymerization) to prepare the aforementioned multifunctional amphiphilic magnetic particles.

[0028] In this invention, addressing the vulnerability of magnetic Fe3O4 particles to acidic solvents, tetraethyl orthosilicate is used to hydrolyze the surface of the magnetic Fe3O4 particles. Through a sol-gel process, a relatively dense silica shell structure is formed on the surface of the magnetic Fe3O4 particles, protecting the internal magnetic Fe3O4 particles. This shell can resist corrosion from hydrochloric acid, sulfuric acid, nitric acid, etc., for a certain period, providing crucial protection for the industrial application of magnetic particles. Furthermore, the silica shell in this invention is a polymer formed by the hydrolysis and condensation of tetraethyl orthosilicate, consisting of a large molecular framework composed of silicon-oxygen bonds. Although the silica shell is relatively dense, intermolecular voids still exist in the SiO2 macromolecular framework formed during the sol-gel process of tetraethyl orthosilicate hydrolysis, ensuring the smooth progress of subsequent acid etching, 4-(chloromethyl)phenyltrimethoxysilane modification, and PDEAEMA grafting.

[0029] In this invention, after acid etching, the magnetic Fe3O4 particles shrink, resulting in core-shell separation. This process further creates defects in the silica shell, even micropores or capillaries. These micropores, together with the intermolecular gaps in the silica shell, form a microporous structure that provides a channel for the transport and migration of partially hydrolyzed polyacrylamide into the silica shell. Acetic acid is used as the etching agent, allowing for slow etching, ensuring a controllable etching process, and making the surface of the magnetic Fe3O4 particle core smoother. If hydrochloric acid, sulfuric acid, or similar substances are used, it is difficult to control the etching process, easily leading to over-etching, which weakens or even completely eliminates the magnetic properties of the particles.

[0030] According to some embodiments of the present invention, the alcohol solvent includes at least one selected from methanol, ethanol, propanol, butanol, isopropanol, and cyclohexanol.

[0031] According to some embodiments of the present invention, the stirring speed in step S2 is 1000-5000 rpm.

[0032] In this invention, the stirring speed in step S2 directly affects the emulsification process of the particulate emulsifier (silicon-coated ferromagnetic particles), directly leading to the stability of the emulsion interface. When the stirring speed is less than 1000 rpm, the stirring speed is too low, making it difficult for the particulate emulsifier to be delivered to the interface, thus failing to stabilize the interface and easily causing demulsification. When the stirring speed is greater than 5000 rpm, the stirring speed is too high, forcing the particulate emulsifier to be pulled at the interface, easily leading to interface instability and demulsification. Therefore, to ensure emulsification and interface stability, the stirring speed in step S2 should preferably be controlled between 1000 and 5000 rpm.

[0033] According to some embodiments of the present invention, the mixing time in step S2 is 3 to 5 minutes.

[0034] According to some embodiments of the present invention, the amino-containing silane coupling agent includes 3-aminopropyltriethoxysilane.

[0035] The local hydrophilic modification of the outer surface of silicon-coated ferromagnetic particles using 3-aminopropyltriethoxysilane was carried out in dimethyl sulfoxide. This was achieved through a hydrolysis process, resulting in a sol-gel composite on the outer surface of the silicon-coated ferromagnetic particles exposed to paraffin. Modifying one side of the outer surface of the silicon-coated ferromagnetic particles with amino groups enabled the adsorption of partially hydrolyzed polyacrylamide.

[0036] According to some embodiments of the present invention, the alkyl-containing silane coupling agent includes n-octyltriethoxysilane.

[0037] The method of locally modifying the outer surface of silicon-coated ferromagnetic particles with n-octyltriethoxysilane involves first removing paraffin wax with an alcohol solvent, exposing the part of the silicon-coated ferromagnetic particles that is embedded in paraffin wax and protected. Then, the exposed part of the silicon-coated ferromagnetic particles is subjected to a sol-gel composite process through the hydrolysis of n-octyltriethoxysilane. Finally, n-octyl groups are modified on the other side of the outer surface of the silicon-coated ferromagnetic particles.

[0038] According to some embodiments of the present invention, the mass ratio of the magnetic Fe3O4 particles to tetraethyl orthosilicate is 1:(0.1-1).

[0039] According to some embodiments of the present invention, the mass ratio of the magnetic Fe3O4 particles to paraffin is 1:(10-200).

[0040] According to some embodiments of the present invention, the mass ratio of paraffin wax to water is 1:(2-10).

[0041] According to some embodiments of the present invention, the mass ratio of the magnetic Fe3O4 particles to the amino-containing silane coupling agent is 1:(0.001-0.01).

[0042] According to some embodiments of the present invention, the mass ratio of the magnetic Fe3O4 particles to the alkyl-containing silane coupling agent is 1:(0.001-0.01).

[0043] According to some embodiments of the present invention, the mass ratio of the magnetic Fe3O4 particles to 4-(chloromethyl)phenyltrimethoxysilane is 1:(0.001-0.01).

[0044] According to some embodiments of the present invention, the mass ratio of the magnetic Fe3O4 particles to diethylaminoethyl methacrylate is 1:(0.02-0.1).

[0045] According to some embodiments of the present invention, the particle size of the magnetic Fe3O4 particles is 100-500 nm.

[0046] According to some embodiments of the present invention, the particle size ratio of the magnetic Fe3O4 particles to the core of the magnetic Fe3O4 particles is 100:(10-99).

[0047] In this invention, if the particle size ratio of magnetic Fe3O4 particles to magnetic Fe3O4 particle cores is less than 100:99, it indicates that the gaps between the silica shell and the magnetic Fe3O4 particle cores are too small, which will affect the adsorption capacity of the magnetic multifunctional amphiphilic particles for partially hydrolyzed polyacrylamide; if the particle size ratio of magnetic Fe3O4 particles to magnetic Fe3O4 particle cores is greater than 100:10, it indicates that the size of the magnetic Fe3O4 particle cores is too small, which will lead to severe magnetic attenuation and make it difficult to achieve magnetic manipulation by an external magnetic field.

[0048] According to some embodiments of the present invention, the grafting reaction includes: dissolving cuprous chloride and 2,2-bipyridine in a solvent, adding amphiphilic modified particles that have undergone modification reaction treatment and diethylaminoethyl methacrylate, and stirring the reaction under a nitrogen atmosphere and at 60-100°C.

[0049] According to some embodiments of the present invention, the solvent used in the grafting reaction includes at least one of water, tetrahydrofuran (THF), and N,N-dimethylformamide (DMF).

[0050] According to some embodiments of the present invention, the stirring reaction time in step S3 is 5 to 6 hours.

[0051] According to some embodiments of the present invention, the stirring reaction time in step S4 is 5 to 6 hours.

[0052] According to some embodiments of the present invention, the magnetic Fe3O4 particles and tetraethyl orthosilicate are dispersed in an alcohol solvent by ultrasonication and stirring for 12 to 24 hours. Preferably, the ultrasonic frequency is 60 to 80 Hz and / or the stirring speed is 50 to 100 rpm.

[0053] According to some embodiments of the present invention, the dispersion of silicon-coated ferromagnetic particles into water is carried out by ultrasound and stirring. Preferably, the ultrasound frequency is 60-80 Hz and / or the stirring speed is 50-100 rpm.

[0054] According to some embodiments of the present invention, the dispersion of paraffin balls into dimethyl sulfoxide is carried out by stirring, preferably at a stirring speed of 50 to 100 rpm;

[0055] According to some embodiments of the present invention, the dispersion of the hydrophilic modified particles in the alcohol solvent is carried out by ultrasound and stirring. Preferably, the ultrasound frequency is 60-80 Hz and / or the stirring speed is 200-300 rpm.

[0056] According to some embodiments of the present invention, the mixing of amphiphilic modified particles with acetic acid for 8-12 hours includes: dispersing the amphiphilic modified particles in water, adding acetic acid, and mixing by means of ultrasound and stirring for 8-12 hours. Preferably, the ultrasound frequency is 60-80 Hz and / or the stirring speed is 50-100 rpm.

[0057] Thirdly, the present invention provides a magnetic multifunctional amphiphilic particle, which is prepared by the preparation method described in the second aspect.

[0058] Fourthly, the present invention provides the application of the magnetic multifunctional amphiphilic particles described in the first aspect or the magnetic multifunctional amphiphilic particles described in the third aspect in the treatment of oily wastewater containing partially hydrolyzed polyacrylamide.

[0059] The beneficial effects of this invention are at least as follows:

[0060] The magnetic multifunctional amphiphilic particles provided by this invention have a wide size distribution window, enabling submicron / micron distribution, and uniform particle size, exhibiting excellent emulsification performance. The droplets stabilized by emulsification using magnetic multifunctional amphiphilic particles can be manipulated by an external magnetic field, achieving oil droplet enrichment and migration, thereby realizing oil-water separation.

[0061] The magnetic multifunctional amphiphilic particles provided by this invention can adsorb some hydrolyzed polyacrylamide, and can efficiently treat oily wastewater containing some hydrolyzed polyacrylamide in one step; at the same time, it can also achieve repeated adsorption and desorption of some hydrolyzed polyacrylamide, so that the magnetic multifunctional amphiphilic particles can be reused many times, and the adsorption capacity for some hydrolyzed polyacrylamide will not decrease significantly, greatly reducing the material cost of wastewater treatment.

[0062] The magnetic multifunctional amphiphilic particles provided by this invention have a structure in which a silica shell coats the magnetic Fe3O4 particle core, which can protect the magnetic Fe3O4 particle core and effectively improve the acid resistance of the amphiphilic particles, making them applicable to the treatment of wastewater with more complex compositions.

[0063] The method for preparing magnetic multifunctional amphiphilic particles provided by this invention is simple, uses low-cost and readily available raw materials, and can achieve industrial-scale mass production at the ton level. Detailed Implementation

[0064] To make the technical problem to be solved, the technical solution, and the beneficial effects of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely for illustrating this patent and do not limit the scope of protection of this invention in any way.

[0065] Unless otherwise defined, the technical terms used in the following embodiments have the same meaning as commonly understood by those skilled in the art. Unless otherwise specified, the reagents used in the following embodiments are conventional biochemical reagents; the raw materials, instruments, and equipment used in the following embodiments can all be obtained commercially or by existing methods; unless otherwise specified, the reagent dosages are those used in routine experimental operations; unless otherwise specified, the experimental methods are conventional methods.

[0066] Example 1

[0067] S1. Disperse 2.0g of magnetic Fe3O4 particles (particle size 0.2μm) in 200mL of ethanol, add 1.0g of tetraethyl orthosilicate, and add 60Hz ultrasound and 100rpm top stirring. Continue ultrasound and stirring to promote the dispersion of magnetic Fe3O4 particles for 12h to obtain silicon-coated iron magnetic particles.

[0068] S2. Disperse the silicon-coated ferromagnetic particles in 200 mL of water while simultaneously applying 60 Hz ultrasound and 100 rpm top-mounted stirring to promote dispersion. Raise the water temperature to 80°C, add 20 g of paraffin wax (phase transition temperature 52°C), and continue stirring until the paraffin wax is completely melted. Turn off the ultrasound and increase the stirring speed to 2000 rpm, stirring continuously for 3 minutes. Stop stirring and heating, cool the sample to room temperature, filter out the solidified paraffin spheres, and separate them from the water. Disperse the paraffin spheres on filter paper and allow them to air dry naturally to obtain paraffin sphere powder formed by silicon-coated ferromagnetic particles embedded in the surface of paraffin wax.

[0069] S3. Disperse the paraffin ball powder in 100 mL of dimethyl sulfoxide and slowly stir the dispersion at 50 rpm using a top-mounted stirrer. Add 20 mg of 3-aminopropyltriethoxysilane to the dispersion and continue stirring for 6 hours. Separate the paraffin ball powder and solvent using an external magnetic field, and allow the paraffin ball powder to air dry naturally. Then disperse the paraffin ball powder in 100 mL of ethanol to dissolve the paraffin. Separate the solid particles using an external magnetic field to obtain Fe3O4@SiO2-NH2 particles with an amino-modified surface on one side.

[0070] S4. Disperse Fe3O4@SiO2-NH2 particles in 100 mL of ethanol. Stir the dispersion using a top-mounted stirrer at 300 rpm, while simultaneously applying 60 Hz ultrasound. Add 20 mg of n-octyltriethoxysilane to the dispersion and continue stirring for 6 h. Separate the solid particles using an external magnetic field to obtain C8-Fe3O4@SiO2-NH2 particles.

[0071] S5. Disperse C8-Fe3O4@SiO2-NH2 particles in 100mL of water, add 2mL of acetic acid, and stir the dispersion for 10h using a top-mounted stirrer at 100rpm, while simultaneously adding 60Hz ultrasound to obtain core-shell separated C8-Fe3O4@SiO2-NH2 particles.

[0072] S6. The core-shell separated C8-Fe3O4@SiO2-NH2 particles were dispersed in 100 mL of ethanol, and 10 mg of 4-(chloromethyl)phenyltrimethoxysilane was added. The mixture was stirred at 100 rpm for 12 h to obtain modified C8-Fe3O4@SiO2-NH2 particles. 0.02 g of cuprous chloride and 0.02 g of 2,2-bipyridine were dissolved in 50 mL of DMF, and the above-mentioned modified C8-Fe3O4@SiO2-NH2 particles were added. At the same time, 0.1 g of DEAEMA was added, and N2 was purged for oxygen removal for 30 min. The temperature was raised to 80 °C, and the mixture was stirred at 100 rpm for 3 h. After the reaction was completed, magnetic multifunctional amphiphilic particles were obtained.

[0073] The magnetic saturation intensity of the magnetic multifunctional amphiphilic particles prepared in this embodiment is 37.5 emu / g, and the X-ray diffraction-XRD results show that it is Fe3O4.

[0074] Example 2

[0075] S1. Disperse 2.0g of magnetic Fe3O4 particles (particle size 0.2μm) in 200mL of ethanol, add 0.3g of tetraethyl orthosilicate, and add 80Hz ultrasound and 80rpm top stirring. Continue ultrasound and stirring to promote the dispersion of magnetic Fe3O4 particles for 24h to obtain silicon-coated iron magnetic particles.

[0076] S2. Disperse the silicon-coated ferromagnetic particles in 200 mL of water while simultaneously applying 80 Hz ultrasound and top-mounted stirring at 80 rpm to promote dispersion. Raise the water temperature to 80°C, add 50 g of paraffin wax (phase transition temperature 52°C), and continue stirring until the paraffin wax is completely melted. Turn off the ultrasound and increase the stirring speed to 1000 rpm, stirring continuously for 5 min. Stop stirring and heating, cool the sample to room temperature, filter out the solidified paraffin spheres, and separate them from the water. Disperse the paraffin spheres on filter paper and allow them to air dry naturally to obtain paraffin sphere powder formed by silicon-coated ferromagnetic particles embedded in the surface of paraffin wax.

[0077] S3. Disperse the paraffin ball powder in 100 mL of dimethyl sulfoxide and slowly stir the dispersion at 80 rpm using a top-mounted stirrer. Add 3 mg of 3-aminopropyltriethoxysilane to the dispersion and continue stirring for 5 h. Separate the paraffin ball powder and solvent using an external magnetic field, and allow the paraffin ball powder to air dry naturally. Then disperse the paraffin ball powder in 100 mL of ethanol to dissolve the paraffin. Separate the solid particles using an external magnetic field to obtain Fe3O4@SiO2-NH2 particles with an amino-modified surface on one side.

[0078] S4. Disperse Fe3O4@SiO2-NH2 particles in 100 mL of ethanol. Stir the dispersion using a top-mounted stirrer at 300 rpm, while simultaneously applying 80 Hz ultrasound. Add 3 mg of n-octyltriethoxysilane to the dispersion and continue stirring for 5 h. Separate the solid particles using an external magnetic field to obtain C8-Fe3O4@SiO2-NH2 particles.

[0079] S5. Disperse C8-Fe3O4@SiO2-NH2 particles in 100mL of water, add 2mL of acetic acid, and stir the dispersion for 8h using a top-mounted stirrer at 80rpm, while simultaneously adding 80Hz ultrasound to obtain core-shell separated C8-Fe3O4@SiO2-NH2 particles.

[0080] S6. The core-shell separated C8-Fe3O4@SiO2-NH2 particles were dispersed in 100 mL of ethanol, and 3 mg of 4-(chloromethyl)phenyltrimethoxysilane was added. The mixture was stirred at 80 rpm for 12 h to obtain modified C8-Fe3O4@SiO2-NH2 particles. 0.02 g of cuprous chloride and 0.02 g of 2,2-bipyridine were dissolved in 50 mL of DMF, and the above-mentioned modified C8-Fe3O4@SiO2-NH2 particles were added. At the same time, 0.04 g of DEAEMA was added, and N2 was purged for oxygen removal for 30 min. The temperature was raised to 80 °C, and the mixture was stirred at 80 rpm for 3 h. After the reaction was completed, magnetic multifunctional amphiphilic particles were obtained.

[0081] Example 3

[0082] S1. Disperse 2.0g of magnetic Fe3O4 particles (particle size 0.2μm) in 200mL of ethanol, add 2.0g of tetraethyl orthosilicate, and add 80Hz ultrasound and 60rpm top stirring. Continue ultrasound and stirring to promote the dispersion of magnetic Fe3O4 particles for 12h to obtain silicon-coated iron magnetic particles.

[0083] S2. Disperse the silicon-coated ferromagnetic particles in 200 mL of water while simultaneously applying 80 Hz ultrasound and top-mounted stirring at 60 rpm to promote dispersion. Raise the water temperature to 80°C, add 20 g of paraffin wax (phase transition temperature 52°C), and continue stirring until the paraffin wax is completely melted. Turn off the ultrasound and increase the stirring speed to 5000 rpm, stirring continuously for 4 min. Stop stirring and heating, cool the sample to room temperature, filter out the solidified paraffin spheres, and separate them from the water. Disperse the paraffin spheres on filter paper and allow them to air dry naturally to obtain paraffin sphere powder formed by silicon-coated ferromagnetic particles embedded in the surface of paraffin wax.

[0084] S3. Disperse the paraffin ball powder in 100 mL of dimethyl sulfoxide and slowly stir the dispersion at 60 rpm using a top-mounted stirrer. Add 10 mg of 3-aminopropyltriethoxysilane to the dispersion and continue stirring for 6 hours. Separate the paraffin ball powder and solvent using an external magnetic field, and allow the paraffin ball powder to air dry naturally. Then disperse the paraffin ball powder in 100 mL of ethanol to dissolve the paraffin. Separate the solid particles using an external magnetic field to obtain Fe3O4@SiO2-NH2 particles with an amino-modified surface on one side.

[0085] S4. Disperse Fe3O4@SiO2-NH2 particles in 100 mL of ethanol. Stir the dispersion using a top-mounted stirrer at 200 rpm, while simultaneously applying 80 Hz ultrasound. Add 10 mg of n-octyltriethoxysilane to the dispersion and continue stirring for 6 h. Separate the solid particles using an external magnetic field to obtain C8-Fe3O4@SiO2-NH2 particles.

[0086] S5. Disperse C8-Fe3O4@SiO2-NH2 particles in 100mL of water, add 2mL of acetic acid, and stir the dispersion for 12h using a top-mounted stirrer at 60rpm, while simultaneously adding 80Hz ultrasound to obtain core-shell separated C8-Fe3O4@SiO2-NH2 particles.

[0087] S6. The core-shell separated C8-Fe3O4@SiO2-NH2 particles were dispersed in 100 mL of ethanol, and 15 mg of 4-(chloromethyl)phenyltrimethoxysilane was added. The mixture was stirred at 60 rpm for 12 h to obtain modified C8-Fe3O4@SiO2-NH2 particles. 0.02 g of cuprous chloride and 0.02 g of 2,2-bipyridine were dissolved in 50 mL of DMF, and the above-mentioned modified C8-Fe3O4@SiO2-NH2 particles were added. At the same time, 0.2 g of DEAEMA was added, and N2 was purged for oxygen removal for 30 min. The temperature was raised to 80 °C, and the mixture was stirred at 60 rpm for 3 h. After the reaction was completed, magnetic multifunctional amphiphilic particles were obtained.

[0088] Example 4

[0089] S1. Disperse 2.0g of magnetic Fe3O4 particles (particle size 0.2μm) in 200mL of ethanol, add 1.0g of tetraethyl orthosilicate, and add 60Hz ultrasound and 100rpm top stirring. Continue ultrasound and stirring to promote the dispersion of magnetic Fe3O4 particles for 12h to obtain silicon-coated iron magnetic particles.

[0090] S2. Disperse the silicon-coated ferromagnetic particles in 200 mL of water while simultaneously applying 60 Hz ultrasound and 100 rpm top-mounted stirring to promote dispersion. Raise the water temperature to 80°C, add 20 g of paraffin wax (phase transition temperature 52°C), and continue stirring until the paraffin wax is completely melted. Turn off the ultrasound and increase the stirring speed to 500 rpm. Due to the low stirring speed, the particles cannot be mechanically delivered to the oil-water interface, the silicon-coated ferromagnetic particles cannot be stably maintained at the oil-water interface, and the oil and water phases cannot be stably emulsified. The aqueous and oil phases remain two separate phases, making it impossible to obtain paraffin sphere powder formed by the silicon-coated ferromagnetic particles embedded on the surface of the paraffin wax.

[0091] Example 5

[0092] S1. Disperse 2.0g of magnetic Fe3O4 particles (particle size 0.2μm) in 200mL of ethanol, add 1.0g of tetraethyl orthosilicate, and add 60Hz ultrasound and 100rpm top stirring. Continue ultrasound and stirring to promote the dispersion of magnetic Fe3O4 particles for 12h to obtain silicon-coated iron magnetic particles.

[0093] S2. Disperse the silicon-coated ferromagnetic particles in 200 mL of water while simultaneously applying 60 Hz ultrasound and 100 rpm top-mounted stirring to promote dispersion. Raise the water temperature to 80°C and add 20 g of paraffin wax (phase transition temperature 52°C), stirring continuously until the paraffin wax is completely melted. Turn off the ultrasound and increase the stirring speed to 6000 rpm. Due to the excessively high stirring speed, although the silicon-coated ferromagnetic particles are mechanically delivered to the oil-water interface for emulsification, the excessively rapid mechanical stirring causes particle peeling at the interface, leading to interface instability and demulsification. This prevents the formation of paraffin sphere powder with silicon-coated ferromagnetic particles embedded on the paraffin wax surface.

[0094] Comparative Example 1

[0095] S1. Disperse 2.0g of magnetic Fe3O4 particles (particle size 0.2μm) in 200mL of ethanol, add 1.0g of tetraethyl orthosilicate, and add 60Hz ultrasound and 100rpm top stirring. Continue ultrasound and stirring to promote the dispersion of magnetic Fe3O4 particles for 12h to obtain silicon-coated iron magnetic particles.

[0096] S2. Disperse the silicon-coated ferromagnetic particles in 200 mL of water while simultaneously applying 60 Hz ultrasound and 100 rpm top-mounted stirring to promote dispersion. Raise the water temperature to 80°C, add 20 g of paraffin wax (phase transition temperature 52°C), and continue stirring until the paraffin wax is completely melted. Turn off the ultrasound and increase the stirring speed to 2000 rpm, stirring continuously for 3 minutes. Stop stirring and heating, cool the sample to room temperature, filter out the solidified paraffin spheres, and separate them from the water. Disperse the paraffin spheres on filter paper and allow them to air dry naturally to obtain paraffin sphere powder formed by silicon-coated ferromagnetic particles embedded in the surface of paraffin wax.

[0097] S3. Disperse the paraffin ball powder in 100 mL of dimethyl sulfoxide and slowly stir the dispersion at 50 rpm using a top-mounted stirrer. Add 20 mg of 3-aminopropyltriethoxysilane to the dispersion and continue stirring for 6 hours. Separate the paraffin ball powder and solvent using an external magnetic field, and allow the paraffin ball powder to air dry naturally. Then disperse the paraffin ball powder in 100 mL of ethanol to dissolve the paraffin. Separate the solid particles using an external magnetic field to obtain Fe3O4@SiO2-NH2 particles with an amino-modified surface on one side.

[0098] S4. Disperse Fe3O4@SiO2-NH2 particles in 100 mL of ethanol. Stir the dispersion using a top-mounted stirrer at 300 rpm, while simultaneously applying 60 Hz ultrasound. Add 20 mg of n-octyltriethoxysilane to the dispersion and continue stirring for 6 h. Separate the solid particles using an external magnetic field to obtain the particles.

[0099] Comparative Example 2

[0100] S1. Disperse 2.0g of magnetic Fe3O4 particles (particle size 0.2μm) in 200mL of ethanol, add 1.0g of tetraethyl orthosilicate, and add 60Hz ultrasound and 100rpm top stirring. Continue ultrasound and stirring to promote the dispersion of magnetic Fe3O4 particles for 12h to obtain silicon-coated iron magnetic particles.

[0101] S2. Disperse the silicon-coated ferromagnetic particles in 100 mL of water, add 2 mL of acetic acid, and stir the dispersion for 10 h using a top-mounted stirrer at 100 rpm, while simultaneously adding 60 Hz ultrasound to obtain core-shell separated silicon-coated ferromagnetic particles.

[0102] S3. The core-shell separated silicon-coated ferromagnetic particles were dispersed in 100 mL of ethanol, and 10 mg of 4-(chloromethyl)phenyltrimethoxysilane was added. The mixture was stirred at 100 rpm for 12 h to obtain modified silicon-coated ferromagnetic particles. 0.02 g of cuprous chloride and 0.02 g of 2,2-bipyridine were dissolved in 50 mL of DMF, and the modified silicon-coated ferromagnetic particles were added. At the same time, 0.1 g of DEAEMA was added, and N2 was purged for deoxygenation for 30 min. The temperature was raised to 80 °C, and the mixture was stirred at 100 rpm for 3 h. After the reaction was completed, particles were obtained.

[0103] Comparative Example 3

[0104] The particles were prepared according to the preparation method of Example 1, except that acetic acid was replaced with an equal volume of dilute hydrochloric acid (pH 6).

[0105] Comparative Example 4

[0106] The granules were prepared according to the preparation method of Example 1, except that acetic acid was replaced with an equal volume of sulfuric acid.

[0107] Performance Evaluation

[0108] (a) The particle size of the particles in each embodiment and comparative example was measured using scanning electron microscopy. The results are shown in the table below:

[0109] Group Particle size (nm) Example 1 220 Example 2 206 Example 3 240 Comparative Example 1 220 Comparative Example 2 220 Comparative Example 3 220 Comparative Example 4 220

[0110] (II) Wastewater Treatment Effect

[0111] One kg of each of the examples and comparative examples was added to 10 t of oily wastewater containing partially hydrolyzed polyacrylamide (COD value 2020, petroleum pollutant content 52.3 mg / L, partially hydrolyzed polyacrylamide content 103.05 mg / L). The wastewater was emulsified by stirring at 1000 rpm for 1 min using a shear mixer. Then, the migration and enrichment of oil droplets emulsified by magnetic particles were controlled by an external magnetic field. The treated wastewater was tested using the methods shown in the table below.

[0112]

[0113] The test results are shown in the table below:

[0114]

[0115]

[0116] (III) Recyclability

[0117] The magnetic multifunctional amphiphilic particles are recycled by washing and regenerating them using a solvent method. The specific processing method includes: collecting the magnetic multifunctional amphiphilic particles prepared in Example 1 after wastewater treatment, washing them with ethanol (ethanol to amphiphilic particles mass ratio of 10:1), and then freeze-drying them to obtain the regenerated particles.

[0118] The treatment process of oily wastewater containing partially hydrolyzed polyacrylamide in the above-mentioned recycled granules (II) showed that the various indicators of the treated wastewater were similar to those of the first wastewater treatment using the magnetic multi-functional amphiphilic granules in Example 1. These magnetic multi-functional amphiphilic granules can be recycled more than 100 times, and their removal efficiency for COD, petroleum hydrocarbons, and partially hydrolyzed polyacrylamide does not significantly decrease.

[0119] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A magnetic multi-effect amphiphilic particle, characterized in that, The magnetic multi-effect amphiphilic particle comprises a core-shell separated magnetic Fe3O4 particle core and a silica shell layer, the outer surface of the silica shell layer comprises a hydrophilic part and a hydrophobic part, the inner surface of the silica shell layer and the surface of the magnetic Fe3O4 particle core are grafted with poly (dimethylaminoethyl methacrylate), and the silica shell layer has a micro-pore structure; The micro-pore structure comprises intermolecular gaps in the silica macromolecular skeleton and defects generated in the core-shell separation process of the silica shell layer and the magnetic Fe3O4 particle core, and includes micropores and capillary pores with a pore size of 0.5-50 nm.

2. The magnetic multi-effect amphiphilic particle according to claim 1, wherein, The hydrophilic part is obtained by modifying the outer surface of the silica shell layer with an amino-containing silane coupling agent; And / or, the hydrophobic part is obtained by modifying the outer surface of the silica shell layer with an alkyl-containing silane coupling agent; And / or, the particle size of the magnetic multi-effect amphiphilic particle is 100 nm < r ≤ 1000 nm.

3. The magnetic multi-effect amphiphilic particle according to claim 2, wherein, The amino-containing silane coupling agent comprises 3-aminopropyl triethoxysilane; And / or, the alkyl-containing silane coupling agent comprises n-octyl triethoxysilane.

4. A method of preparing magnetic multi-effect amphiphilic particles, characterized by, Comprise: S1. Disperse the magnetic Fe3O4 particles and tetraethyl orthosilicate into an alcohol solvent to obtain silicon-coated iron magnetic particles; S2. Disperse the silicon-coated iron magnetic particles into water, add paraffin, heat to completely melt the paraffin, stir and mix, cool, and then filter to obtain paraffin balls formed by embedding the surface of the silicon-coated iron magnetic particles in paraffin; S3. Disperse the paraffin balls into dimethyl sulfoxide, add an amino-containing silane coupling agent, stir and react, disperse the obtained solid particles into an alcohol solvent again to obtain hydrophilic modified particles; S4. Disperse the hydrophilic modified particles into an alcohol solvent, add an alkyl-containing silane coupling agent, stir and react to obtain amphiphilic modified particles; S5. Mix the amphiphilic modified particles with acetic acid for 8-12 h to obtain core-shell separated amphiphilic modified particles; S6. Disperse the core-shell separated amphiphilic modified particles into an alcohol solvent, add 4-(chloromethyl) phenyl trimethoxysilane to modify, and then graft with diethylaminoethyl methacrylate to obtain the magnetic multi-effect amphiphilic particle.

5. The preparation method according to claim 4, characterized in that, The stirring and mixing speed in step S2 is 1000-5000 rpm.

6. The production method according to claim 5, wherein The stirring and mixing time in step S2 is 3-5 min.

7. The production method according to any one of claims 4 to 6, characterized by, The amino-containing silane coupling agent comprises 3-aminopropyl triethoxysilane; And / or, the alkyl-containing silane coupling agent comprises n-octyl triethoxysilane.

8. The production method according to any one of claims 4 to 6, characterized by, The mass ratio of the magnetic Fe3O4 particles to tetraethyl orthosilicate is 1: (0.1-1); And / or, the mass ratio of the magnetic Fe3O4 particles to paraffin is 1: (10-200); And / or, the mass ratio of the magnetic Fe3O4 particles to the amino-containing silane coupling agent is 1: (0.001-0.01); And / or, the mass ratio of the magnetic Fe3O4 particles to the alkyl-containing silane coupling agent is 1: (0.001-0.01); And / or, the mass ratio of the magnetic Fe3O4 particles to 4-(chloromethyl) phenyl trimethoxysilane is 1: (0.001-0.01). And / or, the mass ratio of the magnetic Fe3O4 particles and the diethylaminoethyl methacrylate is 1: (0.02-0.1).

9. The production method according to any one of claims 4 to 6, characterized by, The particle size of the magnetic Fe3O4 particles is 100-500 nm. And / or, the particle size ratio of the magnetic Fe3O4 particles and the core of the magnetic Fe3O4 particles is 100: (10-99).

10. The production method according to any one of claims 4 to 6, characterized by, The grafting reaction comprises: dissolving cuprous chloride and 2,2-bipyridine in a solvent, adding the amphiphilic modified particles and diethylaminoethyl methacrylate after the modification reaction treatment, and stirring and reacting under a nitrogen atmosphere and at 60-100 ℃.

11. A magnetic multi-effect amphiphilic particle prepared by the preparation method of any one of claims 4-10.

12. Application of the magnetic multi-effect amphiphilic particle of any one of claims 1-3 or the magnetic multi-effect amphiphilic particle of claim 11 in treatment of oil-containing wastewater containing partially hydrolyzed polyacrylamide.

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