Preparation method of magnetic response polyionic liquid composite nanoparticles

Abstract

The application discloses a preparation method of magnetic response polyionic liquid composite nanoparticles, and comprises the following steps: step S1, preparing magnetic ferroferric oxide nanoparticles by using a hydrothermal method; step S2, obtaining composite particles of ferroferric oxide and chitosan by using a cross-linking method; and step S3, under the protection of nitrogen, mixing an ionic liquid monomer, an initiator and deionized water, then adding the composite particles of ferroferric oxide and chitosan, and obtaining magnetic response polyionic liquid composite nanoparticles with a three-layer core-shell structure through hydrogen bonding and electrostatic interaction. The physical coating method is adopted to graft the polyionic liquid on the surface of the composite particles of ferroferric oxide and chitosan through hydrogen bonding and electrostatic interaction, and the obtained demulsifier has the three-layer core-shell structure of the magnetic response polyionic liquid composite nanoparticles, can realize efficient separation of emulsified oil wastewater at room temperature, and has excellent salt resistance and recycling performance.

Description

Technical Field

[0001] This invention relates to the field of functionalized magnetic nanomaterials and oil-water emulsion separation technology, and more specifically, to a method for preparing magnetically responsive polyionic liquid composite nanoparticles. Background Technology

[0002] With rapid economic and industrial development, the discharge of oily wastewater has increased significantly. Emulsified oily wastewater containing surfactants, in particular, contains highly stable oily substances due to emulsification, exhibiting characteristics such as being difficult to degrade, posing significant hazards, and carrying high environmental risks. It is the most challenging type of oily wastewater to treat and a key focus of industrial pollution control. How to efficiently treat emulsified oily wastewater to achieve water resource protection and oil recovery has become a global scientific challenge.

[0003] Currently, commonly used methods for treating emulsified oil wastewater mainly include physical methods, chemical methods, and biological demulsification methods. Physical methods, such as thermal separation, membrane separation, and ultrasound, are pollution-free and versatile, but suffer from high costs and unsatisfactory results. Biological methods utilize biological metabolites, resulting in low energy consumption and high efficiency, but generally require a long acclimatization period. Chemical methods primarily reduce the interfacial tension of emulsion droplets by adding chemical demulsifiers, disrupting interfacial membrane stability and promoting droplet aggregation, offering significant advantages such as high efficiency and speed. However, while chemical demulsification is widely used due to its efficiency and speed, traditional chemical demulsifiers are often toxic, easily leaving residues in water bodies and causing secondary pollution. Therefore, developing efficient, low-cost, and easily recyclable chemical demulsifiers has become a research hotspot. Ionic liquids possess advantages such as strong dissolving power, good thermal stability, and high chemical stability. Polyionic liquids retain these advantages while solving problems such as easy loss, imperfect recycling, and the potential for secondary pollution associated with ionic liquids. However, existing technologies still have shortcomings. For example, some studies have used physical coating methods to load polyionic liquids onto the surface of 4A molecular sieves. While this can achieve oil-water separation, it suffers from problems such as difficulty in recovering the demulsifier and long demulsification time. To address this, some researchers have introduced a siloxane interlayer and used a chemical bonding grafting method to polymerize and graft the ionic liquid onto the surface of magnetic nanoparticles. Although this allows for convenient recovery, the preparation process is complex and the demulsification time is still relatively long.

[0004] Chinese invention patent CN201510943538 discloses a method for preparing an amphiphilic cationic chitosan-based magnetic flocculant. This method involves chemically bonding an amphiphilic cationic chitosan graft copolymer to the surface of aldehyde-modified iron oxide nanoparticles. However, this prior art has the following shortcomings: First, it employs a chemical bonding grafting method, which is complex and requires stringent reaction conditions. Second, its flocculant primarily relies on electrostatic and hydrophobic interactions, and its demulsification efficiency needs improvement. Furthermore, the flocculant requires a high dosage when treating emulsified oily wastewater and does not utilize the anion exchange demulsification mechanism unique to ionic liquids.

[0005] Therefore, developing a magnetically responsive demulsifier that is simple to prepare, has high demulsification efficiency, requires low dosage, and is easily recyclable remains a pressing technical problem in this field. The method for preparing magnetically responsive polyionic liquid composite nanoparticles proposed in this invention is of great significance for the research and development of functionalized magnetic nanomaterials and oil-water emulsion separation technologies. Summary of the Invention

[0006] 1. The technical problem that the invention aims to solve

[0007] To address the problems of complex demulsifier preparation processes, long demulsification times, high dosages, and inconvenient recycling in existing technologies, this invention provides magnetically responsive polyionic liquid composite nanoparticles, their preparation method, and applications. This invention employs a physical coating method, grafting polyionic liquid onto the surface of a composite particle of iron oxide and chitosan through hydrogen bonding and electrostatic interactions. The resulting demulsifier is a magnetically responsive polyionic liquid composite nanoparticle with a three-layer core-shell structure—a composite particle of iron oxide, chitosan, and polyionic liquid. It can achieve highly efficient separation of emulsified oily wastewater at room temperature (20–25°C) and exhibits excellent salt resistance and recyclability. This simplifies the demulsifier preparation process, shortens the demulsification time, and facilitates recycling.

[0008] 2. Technical Solution

[0009] To achieve the above objectives, the present invention provides a method for preparing magnetically responsive polyionic liquid composite nanoparticles, characterized by comprising the following steps:

[0010] Step S1: Prepare magnetite nanoparticles using a hydrothermal method;

[0011] Step S2: Using a cross-linking method, chitosan is grafted onto the surface of the magnetite nanoparticles to obtain composite particles of magnetite and chitosan. );

[0012] Step S3: Under nitrogen protection, the ionic liquid monomer, initiator, and deionized water are mixed, and then the composite particles of iron oxide and chitosan are added. Polyionic liquids (PILs) are polymerized and grafted onto the iron oxide and chitosan composite particles through hydrogen bonding and electrostatic interactions. On the surface, magnetically responsive polyionic liquid composite nanoparticles with a three-layer core-shell structure were obtained, namely, composite particles of iron oxide, chitosan, and polyionic liquid. These magnetically responsive polyionic liquid composite nanoparticles served as a demulsifier, and the formula for this demulsifier is as follows: .

[0013] As a further improvement of the present invention, in step 1, the raw materials for preparing the magnetic nanoparticles of iron oxide include ferric chloride hexahydrate, anhydrous sodium acetate, polyethylene glycol and ethylene glycol, wherein the mass ratio of ferric chloride hexahydrate, anhydrous sodium acetate and polyethylene glycol is 1:(2-3):(0.5-1), and the volume ratio of ethylene glycol to the mass of ferric chloride hexahydrate is (20-40) mL:1g.

[0014] As a further improvement of the present invention, the hydrothermal reaction temperature in step 1 is 180-220°C and the reaction time is 6-12 hours.

[0015] As a further improvement of the present invention, in step 2, iron(III) oxide (… The mass ratio of glutaraldehyde to chitosan is (10-50):1, and the crosslinking agent is glutaraldehyde solution. The volume of glutaraldehyde solution is proportional to the volume of iron(III) oxide. The mass ratio of glutaraldehyde to glutaraldehyde is (2-6) mL: 1 g, the mass fraction of glutaraldehyde solution is 25%, the concentration of acetic acid solution is 0.5%-2%, and the cross-linking reaction is carried out at room temperature (20-25℃) for 3-6 h.

[0016] As a further improvement of the present invention, in step 3, the composite particles of iron oxide and chitosan ( The mass ratio of the initiator to the ionic liquid monomer is 1:(1~3), the mass of the initiator is 2%~10% of the mass of the ionic liquid monomer, the volume ratio of deionized water to the mass of the ionic liquid monomer is (50~100)mL:1g, the polymerization grafting reaction temperature is 70~90℃, and the reaction time is 10~16h.

[0017] As a further improvement of the present invention, the ionic liquid monomer is selected from any one of 1-vinyl-3-ethylimidazolium bromide, 1-vinyl-3-butylimidazolium bromide, or 1-vinyl-3-octylimidazolium bromide.

[0018] As a further improvement of the present invention, the structure of the magnetically responsive polyionic liquid composite nanoparticles, from the inside out, consists of: a magnetic core of iron oxide (Fe3O4), a chitosan intermediate layer, and a polyionic liquid functional outer layer; wherein, the chitosan intermediate layer is coated with iron oxide (Fe3O4) via a cross-linking method. On the surface of the chitosan intermediate layer, the polyionic liquid functional outer layer is grafted onto the surface of the chitosan intermediate layer through hydrogen bonding and electrostatic interaction.

[0019] As a further improvement of the present invention, when the magnetically responsive polyionic liquid composite nanoparticles are used for oil-water emulsion separation, demulsification is achieved through anion exchange between the polyionic liquid and the surfactant in the emulsified oil wastewater.

[0020] As a further improvement of the present invention, the oil-water emulsion is an O / W type toluene emulsion, wherein the amount of surfactant added is 0.5 to 2 wt% by weight, and the oil-water volume ratio is 1:(5 to 15).

[0021] A magnetically responsive polyionic liquid composite nanoparticle is prepared by any of the preparation methods described above, and the composite nanoparticle is used for the treatment of emulsified oil wastewater.

[0022] 3. Beneficial effects

[0023] Compared with the prior art, the technical solution provided by this invention has the following advantages:

[0024] (1) The preparation process of this invention is simple, mild, and environmentally friendly. This invention adopts a physical coating method, which grafts polyionic liquid onto the surface of composite particles of iron oxide and chitosan through hydrogen bonding and electrostatic interaction. It does not require complicated chemical bonding steps and avoids the introduction of intermediate layers such as siloxanes. The preparation process of this invention is shorter, simpler to operate, and milder in reaction conditions. Moreover, the chitosan and ionic liquid raw materials used are widely available, biodegradable, and environmentally friendly.

[0025] (2) This invention has high demulsification efficiency and low dosage. The magnetically responsive polyionic liquid composite nanoparticles prepared by this invention have a unique three-layer core-shell structure. The outermost polyionic liquid not only has tunable hydrophilic and hydrophobic properties, but more importantly, it can interact with surfactants in emulsified oil wastewater through anion exchange mechanism, thereby efficiently disrupting the interfacial film stability and promoting oil droplet aggregation; the anion exchange demulsification mechanism of this invention is more efficient, as shown by experiments (see Appendix). Figure 5 The demulsifier of the present invention can achieve excellent demulsification performance at a low dosage.

[0026] (3) The magnetic response characteristics of this invention enable rapid recycling and excellent reusability. This invention uses iron oxide (Fe3O4) as the magnetic core, endowing the composite nanoparticles with superparamagnetism (see Appendix). Figure 2 The hysteresis loop shows high saturation magnetization and low remanence and coercivity. After demulsification, the demulsifier can be quickly recovered and reused by applying an external magnetic field. (See attached image.) Figure 6 As shown, after multiple cycles of use, the demulsifier of the present invention can still maintain a high demulsification efficiency, demonstrating excellent recyclability, effectively reducing processing costs, and avoiding secondary pollution.

[0027] (4) The present invention has good salt resistance and strong adaptability. The magnetically responsive polyionic liquid composite nanoparticles provided by the present invention can still maintain good demulsification performance in saline emulsified oil wastewater. The structural stability of the polyionic liquid shell and its anion exchange mechanism make it less susceptible to interference from inorganic salt ions, and therefore can be widely used in the treatment of emulsified oil wastewater under different salinity conditions, especially in the treatment of industrial saline emulsified oil wastewater.

[0028] (5) The present invention can achieve efficient separation at 20-25℃, and has broad application prospects. The composite nanoparticles prepared by the present invention can achieve efficient separation of water-in-oil toluene emulsions at room temperature. The operation is simple and the energy consumption is low. It has broad application prospects in the fields of emulsified oil wastewater treatment, petrochemicals, and environmental remediation. Attached Figure Description

[0029] Figure 1 for ( and ( Scanning electron microscope (SEM) image; , ( Transmission electron microscope (TEM) image of ).

[0030] Figure 2 for , , The hysteresis loop (VSM) diagram.

[0031] Figure 3 for , , Zeta potential analysis diagram.

[0032] Figure 4 for For water ( Toluene ) and corn germ oil ( Contact angle diagram and For water ( Toluene ) and corn germ oil ( The contact angle diagram.

[0033] Figure 5 Demulsifier Comparison of demulsification performance under different dosages.

[0034] Figure 6 Demulsifier Performance graph for reusable recycling. Detailed Implementation

[0035] To further understand the content of this invention, a detailed description of the invention will be provided in conjunction with the accompanying drawings and embodiments.

[0036] Example 1

[0037] like Figures 1 to 6 As shown in this embodiment, a method for preparing magnetically responsive polyionic liquid composite nanoparticles includes the following steps:

[0038] Step S1: Prepare magnetite nanoparticles using a hydrothermal method;

[0039] Step S2: Using a cross-linking method, chitosan is grafted onto the surface of the magnetite nanoparticles to obtain composite particles of magnetite and chitosan. );

[0040] Step S3: Under nitrogen protection, the ionic liquid monomer, initiator, and deionized water are mixed, and then the composite particles of iron oxide and chitosan are added. Polyionic liquids (PILs) are polymerized and grafted onto the iron oxide and chitosan composite particles through hydrogen bonding and electrostatic interactions. On the surface, magnetically responsive polyionic liquid composite nanoparticles with a three-layer core-shell structure were obtained, namely, composite particles of iron oxide, chitosan, and polyionic liquid. These magnetically responsive polyionic liquid composite nanoparticles served as a demulsifier, and the formula for this demulsifier is as follows: .

[0041] Preferably, in step 1, the raw materials for preparing the magnetite nanoparticles include ferric chloride hexahydrate, anhydrous sodium acetate, polyethylene glycol, and ethylene glycol, wherein the mass ratio of ferric chloride hexahydrate, anhydrous sodium acetate, and polyethylene glycol is 1:2:0.5, and the volume ratio of ethylene glycol to the mass ratio of ferric chloride hexahydrate is 20mL:1g.

[0042] Preferably, the hydrothermal reaction temperature in step 1 is 180°C and the reaction time is 6 hours.

[0043] Preferably, in step 2, iron(III) oxide (Fe3O4) The mass ratio of glutaraldehyde to chitosan is 10:1, and the cross-linking agent is glutaraldehyde solution. The volume of glutaraldehyde solution is proportional to the volume of iron(III) oxide (Fe3O4). The mass ratio of the components was 2 mL: 1 g, the mass fraction of the glutaraldehyde solution was 25%, the concentration of the acetic acid solution was 0.5% to 2%, and the cross-linking reaction was carried out at room temperature (25°C) for 3 hours.

[0044] Preferably, in step 3, the composite particles of iron oxide and chitosan ( The mass ratio of 1-vinyl-3-ethylimidazolium bromide ([VEIm]Br) to 1:1, the mass of the initiator being 2% of the mass of the ionic liquid monomer, the volume ratio of deionized water to the mass of the ionic liquid monomer being 50 mL: 1 g, the polymerization grafting reaction temperature being 70 °C, and the reaction time being 10 h, yielded amphiphilic magnetically responsive polyionic liquid composite nanoparticles. .

[0045] The preparation process in this embodiment is simple, mild, and environmentally friendly. This invention employs a physical coating method, grafting polyionic liquids onto the surface of composite particles of iron oxide and chitosan through hydrogen bonding and electrostatic interactions. This eliminates the need for complex chemical bonding steps and avoids the introduction of intermediate layers such as siloxanes. The preparation process of this invention is shorter, simpler, and uses milder reaction conditions. Furthermore, the chitosan and ionic liquid raw materials used are widely available, biodegradable, and environmentally friendly.

[0046] This embodiment features high demulsification efficiency and low dosage. The magnetically responsive polyionic liquid composite nanoparticles prepared in this invention possess a unique three-layer core-shell structure. The outermost polyionic liquid not only exhibits tunable hydrophilic and hydrophobic properties, but more importantly, it can interact with surfactants in emulsified oily wastewater through an anion exchange mechanism, thereby efficiently disrupting interfacial film stability and promoting oil droplet aggregation. The anion exchange demulsification mechanism of this invention is even more efficient, as demonstrated by experiments (see Appendix). Figure 5 The demulsifier of the present invention can achieve excellent demulsification performance at a low dosage.

[0047] The magnetic response characteristics of this embodiment enable rapid recycling and demonstrate excellent reusability. This invention uses iron oxide (Fe3O4) as the magnetic core, endowing the composite nanoparticles with superparamagnetism (see appendix). Figure 2 The hysteresis loop shows high saturation magnetization and low remanence and coercivity. After demulsification, the demulsifier can be quickly recovered and reused by applying an external magnetic field. (See attached image.) Figure 6 As shown, after multiple cycles of use, the demulsifier of the present invention can still maintain a high demulsification efficiency, demonstrating excellent recyclability, effectively reducing processing costs, and avoiding secondary pollution.

[0048] This embodiment exhibits good salt tolerance and strong adaptability. The magnetically responsive polyionic liquid composite nanoparticles provided by this invention maintain good demulsification performance in saline emulsified oil wastewater. The structural stability of the polyionic liquid shell and its anion exchange mechanism make it less susceptible to interference from inorganic salt ions, thus allowing for wide application in the treatment of emulsified oil wastewater under different salinity conditions, especially in the treatment of industrial saline emulsified oil wastewater.

[0049] This embodiment demonstrates efficient separation at 25°C, indicating broad application prospects. The composite nanoparticles prepared by this invention can achieve efficient separation of oil-in-water toluene emulsions at room temperature, with simple operation and low energy consumption, showing broad application prospects in emulsified oil wastewater treatment, petrochemicals, environmental remediation, and other fields.

[0050] Example 2

[0051] like Figures 1 to 6 As shown, this embodiment describes a method for preparing magnetically responsive polyionic liquid composite nanoparticles. This embodiment is basically the same as Example 1, and preferably includes the following steps:

[0052] Preferably, in step 1, the raw materials for preparing the magnetite nanoparticles include ferric chloride hexahydrate, anhydrous sodium acetate, polyethylene glycol, and ethylene glycol, wherein the mass ratio of ferric chloride hexahydrate, anhydrous sodium acetate, and polyethylene glycol is 1:3:1, and the volume ratio of ethylene glycol to the mass ratio of ferric chloride hexahydrate is 40 mL:1 g.

[0053] Preferably, the hydrothermal reaction temperature in step 1 is 220°C and the reaction time is 12 hours.

[0054] Preferably, in step 2, iron(III) oxide (Fe3O4) The mass ratio of glutaraldehyde to chitosan is 50:1, and the cross-linking agent is glutaraldehyde solution. The volume of glutaraldehyde solution is proportional to the volume of iron(III) oxide (Fe3O4). The mass ratio of the components was 6 mL: 1 g, the mass fraction of the glutaraldehyde solution was 25%, the concentration of the acetic acid solution was 2%, and the cross-linking reaction was carried out at 20°C for 6 h.

[0055] Preferably, in step 3, the composite particles of iron oxide and chitosan ( The mass ratio of 1-vinyl-3-ethylimidazolium bromide ([VEIm]Br) to 1:3, the mass of the initiator being 10% of the mass of the ionic liquid monomer, the volume ratio of deionized water to the mass of the ionic liquid monomer being 100 mL: 1 g, the polymerization grafting reaction temperature being 90 °C, and the reaction time being 16 h, yielded amphiphilic magnetically responsive polyionic liquid composite nanoparticles. .

[0056] This embodiment employs a physical coating method, grafting polyionic liquid onto the surface of composite particles of iron oxide and chitosan through hydrogen bonding and electrostatic interactions. The resulting demulsifier consists of magnetically responsive polyionic liquid composite nanoparticles with a three-layer core-shell structure, namely, composite particles of iron oxide, chitosan, and polyionic liquid. It can achieve efficient separation of emulsified oil wastewater at 20°C and exhibits excellent salt resistance and recyclability, simplifying the demulsifier preparation process, shortening the demulsification time, and facilitating recycling.

[0057] Example 3

[0058] like Figures 1 to 6 As shown, this embodiment describes a method for preparing magnetically responsive polyionic liquid composite nanoparticles. This embodiment is basically the same as Example 1, and preferably includes the following steps:

[0059] Preferably, in step 1, the raw materials for preparing the magnetite nanoparticles include ferric chloride hexahydrate, anhydrous sodium acetate, polyethylene glycol, and ethylene glycol, wherein the mass ratio of ferric chloride hexahydrate, anhydrous sodium acetate, and polyethylene glycol is 1:2.5:0.8, and the volume ratio of ethylene glycol to the mass ratio of ferric chloride hexahydrate is 30 mL:1 g.

[0060] Preferably, the hydrothermal reaction temperature in step 1 is 200°C and the reaction time is 9 hours.

[0061] Preferably, in step 2, iron(III) oxide (Fe3O4) The mass ratio of glutaraldehyde to chitosan is 30:1, and the cross-linking agent is glutaraldehyde solution. The volume of glutaraldehyde solution is proportional to the volume of iron(III) oxide (Fe3O4). The mass ratio of the components was 4 mL: 1 g, the mass fraction of the glutaraldehyde solution was 25%, the concentration of the acetic acid solution was 1.3%, and the cross-linking reaction was carried out at 23°C for 4 h.

[0062] Preferably, in step 3, the composite particles of iron oxide and chitosan ( The mass ratio of 1-vinyl-3-ethylimidazolium bromide ([VEIm]Br) to 1:2, the mass of the initiator being 6% of the mass of the ionic liquid monomer, the volume ratio of deionized water to the mass of the ionic liquid monomer being 80 mL: 1 g, the polymerization grafting reaction temperature being 80 °C, and the reaction time being 13 h, yielded amphiphilic magnetically responsive polyionic liquid composite nanoparticles. .

[0063] This embodiment employs a physical coating method, grafting polyionic liquid onto the surface of composite particles of iron oxide and chitosan through hydrogen bonding and electrostatic interactions. The resulting demulsifier consists of magnetically responsive polyionic liquid composite nanoparticles with a three-layer core-shell structure, namely, composite particles of iron oxide, chitosan, and polyionic liquid. It can achieve efficient separation of emulsified oily wastewater at 23°C and exhibits excellent salt resistance and recyclability. This simplifies the demulsifier preparation process, shortens the demulsification time, and facilitates recycling.

[0064] Example 4

[0065] like Figures 1 to 6 As shown, this embodiment describes a method for preparing magnetically responsive polyionic liquid composite nanoparticles. This embodiment is basically the same as Example 1, but preferably...

[0066] In this embodiment, the magnetic particles of iron oxide (Fe3O) were prepared as follows: 1.35 g of ferric chloride hexahydrate (FeCl3⋅6H2O), 3.6 g of anhydrous sodium acetate (CH3COONa), and 1 g of polyethylene glycol (PEG-4000) were dissolved in 40 mL of ethylene glycol (EG) and sonicated for 30 min to form a homogeneous mixture. The mixture was then transferred to a 100 mL reactor and placed in a vacuum drying oven at 200 °C for 8 h. After the reaction, the mixture was allowed to cool naturally to room temperature and washed three times with deionized water and anhydrous ethanol. The magnetic iron oxide nanoparticles were obtained after vacuum drying at 70 °C for 12 h. The composite particles of iron oxide and chitosan (…) Preparation of Fe3O4 nanoparticles: 0.5g Fe3O4 nanoparticles were added to 20mL of 1% acetic acid, and 20mg chitosan was added. After ultrasonic homogenization, the suspension was transferred to a three-necked flask, and 2mL of 25% glutaraldehyde solution was added. The cross-linking reaction was carried out at room temperature for 4h. The resulting product was washed three times alternately with deionized water and ethanol, and then vacuum dried at 70℃ for 12h to obtain composite particles of Fe3O4 and chitosan. ).

[0067] Preferred amphiphilic magnetically responsive polyionic liquid composite nanoparticles Preparation: Under nitrogen protection, 0.35 g of 1-vinyl-3-ethylimidazolium bromide ([VEIm]Br), 0.02 g of initiator azobisisobutyronitrile (AIBN), and 25 mL of deionized water were added sequentially to a 50 mL single-necked round-bottom flask. The mixture was stirred at 22 °C until a homogeneous and transparent solution was obtained. Then, 0.2 g of... The reaction was mechanically stirred at 80ºC for 12 h. After the reaction, the product was washed three times alternately with deionized water and acetone. Finally, the polymer was vacuum dried at 70ºC for 12 h to obtain amphiphilic magnetically responsive polyionic liquid composite nanoparticles. .

[0068] In this embodiment, the above-mentioned magnetically responsive polyionic liquid demulsifier was added to emulsified oil wastewater (toluene droplets, oil:water = 1:9, demulsifier particle concentration of 40 g / L). The demulsification results showed that the demulsification rate could reach 98.1% when the demulsification time was 10 min. After demulsification and regeneration, the demulsification performance was still above 93.2% after 10 cycles.

[0069] This embodiment employs a physical coating method, grafting polyionic liquid onto the surface of composite particles of iron oxide and chitosan through hydrogen bonding and electrostatic interactions. The resulting demulsifier consists of magnetically responsive polyionic liquid composite nanoparticles with a three-layer core-shell structure, namely, composite particles of iron oxide, chitosan, and polyionic liquid. It can achieve efficient separation of emulsified oily wastewater at 22°C and exhibits excellent salt resistance and recyclability. This simplifies the demulsifier preparation process, shortens the demulsification time, and facilitates recycling.

[0070] Example 5

[0071] like Figures 1 to 6 As shown, this embodiment describes a method for preparing magnetically responsive polyionic liquid composite nanoparticles. This embodiment is basically the same as Example 1. Preferably, in this embodiment, under nitrogen protection, 0.35 g of 1-vinyl-3-butylimidazolium bromide ([VBIm]Br), 0.02 g of initiator azobisisobutyronitrile (AIBN), and 25 mL of deionized water are added sequentially to a 50 mL single-necked round-bottom flask. The mixture is stirred at 24 °C until a homogeneous and transparent solution is obtained. Subsequently, 0.2 g of... The reaction was mechanically stirred at 80ºC for 12 h. After the reaction, the product was washed three times alternately with deionized water and acetone. Finally, the polymer was vacuum dried at 70ºC for 12 h to obtain amphiphilic magnetically responsive polyionic liquid composite nanoparticles. .

[0072] In this embodiment, the above-mentioned magnetically responsive polyionic liquid demulsifier was added to emulsified oil wastewater (toluene droplets, oil:water = 1:9, demulsifier particle concentration of 40g / L). The demulsification results showed that the demulsification rate could reach 95.3% when the demulsification time was 10min.

[0073] This embodiment employs a physical coating method, grafting polyionic liquid onto the surface of composite particles of iron oxide and chitosan through hydrogen bonding and electrostatic interactions. The resulting demulsifier consists of magnetically responsive polyionic liquid composite nanoparticles with a three-layer core-shell structure, namely, composite particles of iron oxide, chitosan, and polyionic liquid. It can achieve efficient separation of emulsified oil wastewater at 24°C and exhibits excellent salt resistance and recyclability. This simplifies the demulsifier preparation process, shortens the demulsification time, and facilitates recycling.

[0074] Example 6

[0075] like Figures 1 to 6As shown, this embodiment describes a method for preparing magnetically responsive polyionic liquid composite nanoparticles. This embodiment is basically the same as Example 1. Preferably, in this embodiment, under nitrogen protection, 0.35 g of 1-vinyl-3-octylimidazolium bromide ([VOIm]Br), 0.02 g of initiator azobisisobutyronitrile (AIBN), and 25 mL of deionized water are added sequentially to a 50 mL single-necked round-bottom flask. The mixture is stirred at 21 °C until a homogeneous and transparent solution is obtained. Subsequently, 0.2 g of... The reaction was mechanically stirred at 80ºC for 12 h. After the reaction, the product was washed three times alternately with deionized water and acetone. Finally, the polymer was vacuum dried at 70ºC for 12 h to obtain amphiphilic magnetically responsive polyionic liquid composite nanoparticles. .

[0076] In this embodiment, the above-mentioned magnetically responsive polyionic liquid demulsifier was added to emulsified oil wastewater (toluene droplets, oil:water = 1:9, demulsifier particle concentration of 40g / L). The demulsification results showed that the demulsification rate could reach 98.3% when the demulsification time was 10min.

[0077] This embodiment employs a physical coating method, grafting polyionic liquid onto the surface of composite particles of iron oxide and chitosan through hydrogen bonding and electrostatic interactions. The resulting demulsifier consists of magnetically responsive polyionic liquid composite nanoparticles with a three-layer core-shell structure, namely, composite particles of iron oxide, chitosan, and polyionic liquid. It can achieve efficient separation of emulsified oil wastewater at 21°C and exhibits excellent salt resistance and recyclability, simplifying the demulsifier preparation process, shortening the demulsification time, and facilitating recycling.

[0078] Example 7

[0079] like Figures 1 to 6 As shown, this embodiment describes a method for preparing magnetically responsive polyionic liquid composite nanoparticles. This embodiment is basically the same as that of Embodiments 1 to 6. Preferably, the ionic liquid monomer is selected from any one of 1-vinyl-3-ethylimidazolium bromide, 1-vinyl-3-butylimidazolium bromide, or 1-vinyl-3-octylimidazolium bromide.

[0080] Preferably, the structure of the magnetically responsive polyionic liquid composite nanoparticles, from the inside out, consists of: a magnetite core, a chitosan intermediate layer, and a polyionic liquid functional outer layer; wherein the chitosan intermediate layer is coated with magnetite (Fe3O4) via a cross-linking method. On the surface of the chitosan intermediate layer, the polyionic liquid functional outer layer is grafted onto the surface of the chitosan intermediate layer through hydrogen bonding and electrostatic interaction.

[0081] Preferably, when the magnetically responsive polyionic liquid composite nanoparticles are used for oil-water emulsion separation, demulsification is achieved through anion exchange between the polyionic liquid and the surfactant in the emulsified oil wastewater.

[0082] This embodiment employs a physical coating method, grafting polyionic liquid onto the surface of composite particles of iron oxide and chitosan through hydrogen bonding and electrostatic interactions. The resulting demulsifier consists of magnetically responsive polyionic liquid composite nanoparticles with a three-layer core-shell structure, namely, composite particles of iron oxide, chitosan, and polyionic liquid. It can achieve efficient separation of emulsified oily wastewater at room temperature and exhibits excellent salt resistance and recyclability. This simplifies the demulsifier preparation process, shortens the demulsification time, and facilitates recycling.

[0083] Example 8

[0084] like Figures 1 to 6 As shown, this embodiment describes a method for preparing magnetically responsive polyionic liquid composite nanoparticles. This embodiment is basically the same as that in Embodiment 7. Preferably, the oil-water emulsion is an O / W type toluene emulsion, wherein the amount of surfactant added is 0.5-2 wt% by weight, and the oil-water volume ratio is 1:(5-15).

[0085] In this embodiment, the amount of surfactant added is 0.5 wt% by weight, and the oil-water volume ratio is 1:5.

[0086] This embodiment employs a physical coating method, grafting polyionic liquid onto the surface of composite particles of iron oxide and chitosan through hydrogen bonding and electrostatic interactions. The resulting demulsifier consists of magnetically responsive polyionic liquid composite nanoparticles with a three-layer core-shell structure, namely, composite particles of iron oxide, chitosan, and polyionic liquid. It can achieve efficient separation of emulsified oily wastewater at room temperature and exhibits excellent salt resistance and recyclability. This simplifies the demulsifier preparation process, shortens the demulsification time, and facilitates recycling.

[0087] Example 9

[0088] like Figures 1 to 6 As shown, this embodiment describes a method for preparing magnetically responsive polyionic liquid composite nanoparticles. This embodiment is basically the same as any of the embodiments 1 to 8. Preferably, the oil-water emulsion is an O / W type toluene emulsion, wherein the amount of surfactant added is 0.5 to 2 wt% by weight, and the oil-water volume ratio is 1:(5 to 15).

[0089] In this embodiment, the amount of surfactant added is 2 wt% by weight, and the oil-water volume ratio is 1:15.

[0090] This embodiment employs a physical coating method, grafting polyionic liquid onto the surface of composite particles of iron oxide and chitosan through hydrogen bonding and electrostatic interactions. The resulting demulsifier consists of magnetically responsive polyionic liquid composite nanoparticles with a three-layer core-shell structure, namely, composite particles of iron oxide, chitosan, and polyionic liquid. It can achieve efficient separation of emulsified oily wastewater at room temperature and exhibits excellent salt resistance and recyclability. This simplifies the demulsifier preparation process, shortens the demulsification time, and facilitates recycling.

[0091] Example 10

[0092] like Figures 1 to 6 As shown, this embodiment describes a method for preparing magnetically responsive polyionic liquid composite nanoparticles. This embodiment is basically the same as any of the embodiments 1 to 8. Preferably, the oil-water emulsion is an O / W type toluene emulsion, wherein the amount of surfactant added is 0.5 to 2 wt% by weight, and the oil-water volume ratio is 1:(5 to 15).

[0093] In this embodiment, the amount of surfactant added is 1.2 wt% by weight, and the oil-water volume ratio is 1:10.

[0094] This embodiment employs a physical coating method, grafting polyionic liquid onto the surface of composite particles of iron oxide and chitosan through hydrogen bonding and electrostatic interactions. The resulting demulsifier consists of magnetically responsive polyionic liquid composite nanoparticles with a three-layer core-shell structure, namely, composite particles of iron oxide, chitosan, and polyionic liquid. It can achieve efficient separation of emulsified oily wastewater at room temperature and exhibits excellent salt resistance and recyclability. This simplifies the demulsifier preparation process, shortens the demulsification time, and facilitates recycling.

[0095] Example 11

[0096] like Figures 1 to 6 As shown, this embodiment is a magnetically responsive polyionic liquid composite nanoparticle. This embodiment is basically the same as any of the embodiments 1 to 10. Preferably, it is prepared by any of the preparation methods described above, and the composite nanoparticle is used for emulsified oil wastewater treatment.

[0097] This embodiment employs a physical coating method, grafting polyionic liquid onto the surface of composite particles of iron oxide and chitosan through hydrogen bonding and electrostatic interactions. The resulting demulsifier consists of magnetically responsive polyionic liquid composite nanoparticles with a three-layer core-shell structure, namely, composite particles of iron oxide, chitosan, and polyionic liquid. It can achieve efficient separation of emulsified oily wastewater at room temperature and exhibits excellent salt resistance and recyclability. This simplifies the demulsifier preparation process, shortens the demulsification time, and facilitates recycling.

[0098] The present invention and its embodiments have been described above illustratively. This description is not restrictive, and the figures shown are only one embodiment of the present invention; the actual structure is not limited thereto. Therefore, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the present invention, such designs should fall within the protection scope of the present invention.

Claims

1. A method for preparing magnetically responsive polyionic liquid composite nanoparticles, characterized in that, Includes the following steps: Step S1: Prepare magnetite nanoparticles using a hydrothermal method; Step S2: Using a cross-linking method, chitosan is grafted onto the surface of the magnetite nanoparticles to obtain composite particles of magnetite and chitosan. Step S3: Under nitrogen protection, the ionic liquid monomer, initiator and deionized water are mixed and then the composite particles of iron oxide and chitosan are added. Through hydrogen bonding and electrostatic interaction, the polyionic liquid is polymerized and grafted onto the surface of the composite particles of iron oxide and chitosan to obtain magnetically responsive polyionic liquid composite nanoparticles with a three-layer core-shell structure, namely, composite particles of iron oxide, chitosan and polyionic liquid.

2. The preparation method according to claim 1, characterized in that, In step 1, the raw materials for preparing the magnetic nanoparticles of iron oxide include ferric chloride hexahydrate, anhydrous sodium acetate, polyethylene glycol, and ethylene glycol, wherein the mass ratio of ferric chloride hexahydrate, anhydrous sodium acetate, and polyethylene glycol is 1:(2-3):(0.5-1), and the volume ratio of ethylene glycol to the mass ratio of ferric chloride hexahydrate is (20-40) mL:1 g.

3. The preparation method according to claim 2, characterized in that, In step 1, the hydrothermal reaction temperature is 180–220°C, and the reaction time is 6–12 hours.

4. The preparation method according to claim 1, characterized in that, In step 2, the mass ratio of iron oxide to chitosan is (10-50):1, the crosslinking agent is glutaraldehyde solution, the volume ratio of glutaraldehyde solution to the mass of iron oxide is (2-6) mL:1g, the mass fraction of glutaraldehyde solution is 25%, the concentration of acetic acid solution is 0.5%-2%, and the crosslinking reaction is carried out at 20-25℃ for 3-6 hours.

5. The preparation method according to claim 1, characterized in that, In step 3, the mass ratio of the composite particles of iron oxide and chitosan to the ionic liquid monomer is 1:(1-3), the mass of the initiator is 2%-10% of the mass of the ionic liquid monomer, the volume ratio of deionized water to the mass of the ionic liquid monomer is (50-100) mL:1g, the polymerization grafting reaction temperature is 70-90℃, and the reaction time is 10-16h.

6. The preparation method according to claim 1, characterized in that, The ionic liquid monomer is selected from any one of 1-vinyl-3-ethylimidazolium bromide, 1-vinyl-3-butylimidazolium bromide, or 1-vinyl-3-octylimidazolium bromide.

7. The preparation method according to claim 1, characterized in that, The structure of the magnetically responsive polyionic liquid composite nanoparticles, from the inside out, consists of: a magnetic core of iron oxide, a chitosan intermediate layer, and a polyionic liquid functional outer layer; wherein, the chitosan intermediate layer is coated on the surface of iron oxide by cross-linking, and the polyionic liquid functional outer layer is grafted onto the surface of the chitosan intermediate layer by hydrogen bonding and electrostatic interaction.

8. The preparation method according to claim 1, characterized in that, When the magnetically responsive polyionic liquid composite nanoparticles are used for oil-water emulsion separation, demulsification is achieved through anion exchange between the polyionic liquid and the surfactant in the emulsified oil wastewater.

9. The preparation method according to claim 8, characterized in that, The oil-water emulsion is an O / W type toluene emulsion, wherein the amount of surfactant added is 0.5-2 wt%, and the oil-water ratio is 1:(5-15).

10. A magnetically responsive polyionic liquid composite nanoparticle, characterized in that, The composite nanoparticles are prepared by any one of claims 1 to 9 and are used for the treatment of emulsified oil wastewater.

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