A universal method for preparing magnetic adsorbents based on physical blending

Abstract

This invention belongs to the field of environmental functional materials and pollution remediation technology, specifically relating to a universal method for preparing magnetic adsorbents based on physical blending. The method involves mixing magnetic colloidal particles and non-magnetic colloidal particles in a solution, adjusting the electrolyte concentration by adding salt to induce colloidal aggregation, and then using ultrasound or vortexing to ensure uniform particle mixing. After settling, the obtained magnetic adsorbent is collected using an external magnetic field. Its mechanism is characterized by the colloidal aggregation effect based on the DLVO theory of particle interaction. By controlling the salt concentration, the relative magnitudes of electrostatic repulsion and van der Waals attraction are adjusted, thereby driving colloidal aggregation and forming a magnetic adsorbent. This invention does not require complex chemical modification or high-temperature treatment, retains the original structure, adsorption performance, and extraction performance of the adsorbent, and imparts magnetic separation properties. It also has advantages such as simple operation, low cost, and strong universality, and has broad application prospects in the large-scale preparation of magnetic adsorbents.

Description

Technical Field

[0001] This invention belongs to the field of environmental functional materials and pollution remediation technology, specifically relating to a universal method for preparing magnetic adsorbents based on physical blending. Background Technology

[0002] Magnetic adsorbents typically consist of magnetic particles and an adsorbent, with the magnetic particles serving as the carrier of the adsorbent. These magnetic particles possess high magnetic permeability and magnetic saturation, enabling them to generate strong magnetic fields, thereby achieving the adsorption and separation of substances. Applications of magnetic adsorbents include water treatment, environmental protection, biomedicine, and food processing. In water treatment, they show broad application prospects, removing heavy metal ions, organic pollutants, and other harmful substances from water, improving water safety and cleanliness. In environmental protection, magnetic adsorbents can be used to treat industrial wastewater and for soil remediation. By adsorbing and removing pollutants from the environment, they contribute to protecting the ecological environment and human health. In biomedicine, they can be used for targeted drug delivery, cell separation and purification, etc. Through the magnetic responsiveness of magnetic adsorbents, precise release of drugs at specific sites and efficient separation from cells can be achieved. In the food processing industry, they can also be used for the detection of harmful substances.

[0003] In recent years, a large number of magnetic adsorbents have been developed through the functionalization of magnetic materials and various other materials, including graphene / graphene oxide, carbon nanotubes, metal-organic frameworks, covalent organic frameworks, molecularly imprinted materials, nanocomposites, and polymers. However, the synthesis processes of these magnetic adsorbents are complex and time-consuming, preventing large-scale production and limiting their development in practical applications. The inventors of this invention previously obtained magnetic molecularly imprinted adsorbents by physically mixing and vortexing iron oxide nanoparticles (MNPs) and molecularly imprinted polymers (MIPs) (J. Chromatogr. A., 2014, 1329, 17–23). This method is simple and convenient, significantly reducing preparation costs while maintaining the excellent extraction performance of the adsorbent itself. However, because the principle behind this method has not yet been revealed, it is currently limited to specific particle systems and cannot be universally applied by adjusting other parameters, which seriously hinders its use and development in the preparation of magnetic adsorbents. Summary of the Invention

[0004] The purpose of this invention is to provide a universal method for preparing magnetic adsorbents based on physical blending. This method is characterized by simple operation, controllable conditions, low cost, and does not damage the structural properties of the adsorbent itself.

[0005] To achieve the above objectives, the following technical solution is adopted:

[0006] A universal method for preparing magnetic adsorbents based on physical blending includes the following steps:

[0007] A mixed solution of magnetic colloidal particles and non-magnetic colloidal adsorbent is prepared, and an aqueous solution of sodium or potassium salt is added; the two colloidal particles are thoroughly mixed and aggregated, and the magnetic adsorbent is collected by an external magnetic field after standing.

[0008] Furthermore, the magnetic colloidal particles are one of Fe3O4, Fe2O3, or MnFe2O4 (preferably Fe3O4).

[0009] Furthermore, the non-magnetic colloidal particles are one of carbon-based materials, silicon-based materials, polymer-based materials, or bio-based materials; and / or

[0010] The carbon-based material is one of graphene microsheets or multi-walled carbon nanotubes (preferably graphene microsheets); and / or

[0011] The silicon-based material is one of silica gel, hydrophilic fumed silica nanoparticles, and hydrophobic fumed silica nanoparticles (preferably silica gel); and / or

[0012] The polymer-based material is one of monodisperse polystyrene microspheres, monodisperse carboxylated polystyrene microspheres, or monodisperse amino polystyrene microspheres (preferably monodisperse amino polystyrene microspheres); and / or

[0013] The biomaterial is nanoparticles from the ink sac of a cuttlefish.

[0014] Furthermore, the magnetic colloidal particles have a particle size range of 10 nm to 2 μm (preferably 10 to 500 nm); and / or

[0015] The particle size of the non-magnetic colloidal particles is 10nm-100μm (preferably 200nm-10μm).

[0016] Furthermore, the solvent of the mixed solution is one of water, ethanol, acetone, and acetonitrile (preferably water).

[0017] Furthermore, the concentration of magnetic colloidal particles in the mixed solution is 0.1-5 mg·mL. –1 (Preferred to be 0.5 mg·mL) –1 ); and / or

[0018] The concentration of non-magnetic colloidal particles in the mixed solution is 0.05-5 mg / mL. –1 (Preferred to be 0.5 mg·mL) –1 ).

[0019] The sodium salt is sodium chloride or sodium nitrate, and the potassium salt is potassium chloride or potassium nitrate; and / or

[0020] After adding the aqueous solution of the sodium or potassium salt, the concentration of the sodium or potassium salt in the resulting solution is 0.001-5M.

[0021] Furthermore, the method for thoroughly mixing the two colloidal particles is ultrasonication or vortexing for 1-10 minutes (preferably vortexing for 2 minutes); the settling time is 5-10 minutes (preferably 5 minutes).

[0022] The present invention also provides a magnetic adsorbent prepared by the universal method for preparing magnetic adsorbents based on physical blending.

[0023] The present invention also provides the application of the magnetic adsorbent prepared by the universal method of preparing magnetic adsorbent based on physical blending in the removal of Benvimod.

[0024] Following the general method for preparing magnetic adsorbents based on physical blending described above, the ratio of magnetic to non-magnetic materials in the magnetic adsorbent can be adjusted as needed by controlling the concentration of magnetic colloidal particles. A higher proportion of magnetic colloidal particles results in stronger magnetism and faster particle recovery; a higher proportion of non-magnetic colloidal particles leads to better adsorption performance.

[0025] By controlling the electrolyte concentration in the system, the van der Waals forces between particles can be increased, thereby achieving the aggregation and bonding of different particle systems.

[0026] The mechanism of this invention lies in the colloidal coagulation effect based on the DLVO theory, where the interparticle interactions are primarily influenced by van der Waals attraction and electrostatic repulsion between colloidal particles. As the electrolyte concentration in the system increases, the electrostatic repulsion weakens due to spatial shielding, thus enhancing the coagulation effect.

[0027] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0028] This invention provides a universal method for preparing magnetic adsorbents based on physical blending, which is safe, economical, simple to operate, environmentally friendly, and has excellent performance. It has broad application prospects in the field of large-scale preparation of magnetic adsorbents.

[0029] The method of this invention is applicable to magnetic and non-magnetic materials with different physicochemical properties (including surface charge, surface functional groups, hydrophilicity / hydrophobicity, particle size, etc.).

[0030] The present invention provides a universal method for preparing magnetic adsorbents based on physical blending, which can impart magnetic characteristics to solid-phase adsorbents while maintaining their good adsorption performance and extraction ability. Attached Figure Description

[0031] Figure 1Characterization of MNPs-1 in Example 1: a) Electron microscopy image, b) X-ray diffraction pattern, c) Zeta potential map, d) Magnetic saturation intensity curve, e) Contact angle;

[0032] Figure 2 Scanning electron microscope images of CINPs in Example 1;

[0033] Figure 3 Example 1: Macroscopic image of magnetic adsorbent collected under a magnetic field;

[0034] Figure 4 : Chromatogram of benvitimide at a concentration of 100 ppm in Example 1;

[0035] Figure 5 : Chromatogram of benvitimide at a concentration of 350 ppm in Example 1;

[0036] Figure 6 Scanning electron microscope image of the magnetic adsorbent prepared in Example 1;

[0037] Figure 7 Characterization of graphene microsheets in Example 2: a) morphology under an inverted optical microscope, b) zeta potential diagram;

[0038] Figure 8 In Example 2, a) macroscopic image of MNPs-1 and graphene microsheets without NaCl added, without the application of a magnetic field; b) macroscopic image of magnetic adsorbent collected under a magnetic field without the addition of NaCl solution; c) macroscopic image of magnetic adsorbent collected under a magnetic field, with NaCl concentration of 0.1M.

[0039] Figure 9 Scanning electron microscope images of graphene microsheets and MNPs-1 before and after physical mixing in Example 2: a. after mixing, b. before mixing;

[0040] Figure 10 Characterization of Si-MPs in Example 3: a) Scanning electron microscope image, b) X-ray diffraction pattern, c) zeta potential diagram, d) magnetic saturation intensity curve, e) contact angle;

[0041] Figure 11 Microscopic dynamics of Si-MPs and graphene microsheets without a magnetic field in Example 3;

[0042] Figure 12 : Microscopic dynamics of Si-MPs and graphene microsheets under magnetic field in Example 3; H represents magnetic field, and the arrow points to the direction of magnetic field;

[0043] Figure 13 Example 3 shows the timeline of separation of magnetic adsorbents prepared at different NaCl concentrations (a 0.1 M, b 0.5 M, c 1 M) under the action of a magnetic field.

[0044] Figure 14 Characterization of COOH-PS microspheres in Example 4: a) Morphology under an inverted optical microscope, b) Zeta potential diagram;

[0045] Figure 15 Characterization of MNPs-3 in Example 5: a) Scanning electron microscope image, b) X-ray diffraction pattern, c) Zeta potential map, d) Magnetic saturation intensity curve, e) Contact angle;

[0046] Figure 16 Example 5: Macroscopic time series diagram of magnetic adsorbent collected under a magnetic field when no KCl aqueous solution was added;

[0047] Figure 17 : Macroscopic time series diagram of magnetic adsorbent collection under magnetic field in Comparative Example 1;

[0048] Figure 18 Comparative Example 1: Microscopic dynamics of MNPs-1 and graphene microsheets before and after the application of a magnetic field. H represents the magnetic field, and the arrows indicate the direction of the magnetic field.

[0049] Figure 19 Scanning electron microscope image of graphene microsheets and MNPs-1 physically mixed in Comparative Example 1;

[0050] Figure 20 In Comparative Example 1, macroscopic time-series graphs of the magnetic adsorbent at different MNPs-1 concentrations were collected under a magnetic field, a 0.25 mg·mL –1 b 0.75 mg·mL –1 c 1mg·mL –1 ;

[0051] Figure 21 Characterization of PS microspheres in Comparative Example 2: a. Morphology under an inverted optical microscope, b. Zeta potential diagram;

[0052] Figure 22 Microscopic dynamics of MNPs-1 and PS microspheres without a magnetic field in Comparative Example 2;

[0053] Figure 23 Comparative Example 2: Microscopic dynamics of MNPs-1 and PS microspheres under a magnetic field. H represents the magnetic field, and the arrows indicate the direction of the magnetic field.

[0054] Figure 24 Scanning electron microscope image of the magnetic adsorbent prepared in Comparative Example 2;

[0055] Figure 25 Characterization of silica gel in Comparative Example 3: a. Morphology under an inverted optical microscope, b. Zeta potential diagram;

[0056] Figure 26 Characterization of MNPs-2 in Comparative Example 7: a. Scanning electron microscope image, b. X-ray diffraction pattern, c. Zeta potential map, d. Magnetic saturation intensity curve, e. Contact angle. Detailed Implementation

[0057] The following embodiments further illustrate the technical solution of the present invention, but are not intended to limit the scope of protection of the present invention.

[0058] Unless otherwise specified, all materials and reagents used in this invention are commercially available conventional materials and reagents.

[0059] In the example:

[0060] Nano-iron oxide particles coated with silica (Si-MPs, purchased from Suzhou Nanomicro Technology Co., Ltd., particle size 500nm); first type of nano-iron oxide particles (MNPs-1, particle size 60-450nm); second type of nano-iron oxide particles (MNPs-2, particle size 30nm); third type of nano-iron oxide particles (MNPs-3, purchased from Shanghai Maclean Biochemical Technology Co., Ltd., particle size 10-30nm); silica gel (purchased from Qingdao Xinlida Silica Gel Co., Ltd., irregular sheet structure, particle size approximately 40μm); hydrophilic vapor-phase silica gel nanoparticles (purchased from Shanghai Ron Reagent, irregular sheet structure, particle size approximately 50-100μm); hydrophobic vapor-phase silica gel nanoparticles (purchased from Shanghai Ron Reagent, irregular sheet structure, particle size approximately 10-20μm); graphene microsheets (purchased from Shanghai...). THIAI Chemical Industry Development Co., Ltd.; two-dimensional sheet-like structure, particle size 2-20μm); monodisperse polystyrene microspheres (purchased from Tianjin Da'e Technology Co., Ltd., spherical structure, 500nm; 3μm; 10μm); monodisperse carboxylated polystyrene microspheres (purchased from Tianjin Da'e Technology Co., Ltd., spherical, particle size 3μm); monodisperse amino polystyrene microspheres (purchased from Tianjin Da'e Technology Co., Ltd., spherical, particle size 3μm); multi-walled carbon nanotubes (purchased from Shanghai Maclean Biochemical Technology Co., Ltd., particle size 60-100nm, length 5-15μm); copper nitrate trihydrate (purchased from Shanghai Maclean Biochemical Technology Co., Ltd.); nanoparticles in cuttlefish ink sacs (CINPs, regular spherical, average particle size 100nm); Tapinarof (purchased from Shanghai Maclean Biochemical Technology Co., Ltd.);

[0061] The first method for preparing nano-iron oxide particles (MNPs-1) is as follows: FeCl3·6H2O (1.35g) and ethylene glycol (40mL) are mixed to form a clear aqueous solution. Sodium acetate (3.6g) and polyethylene glycol (MW=2000, 1.0g) are added. After stirring at 1000rpm for 30 minutes, the mixture is transferred to a high-pressure reactor and reacted at 200℃ for 8 hours. After cooling to room temperature, the mixture is centrifuged at 8000rpm for 3 minutes, washed with ethanol and water 4 times each, and dried at 60℃ for 6 hours to obtain MNPs-1.

[0062] The second method for preparing nano-iron oxide particles (MNPs-2) is as follows: FeCl3·6H2O (5g) and ethylene glycol (100mL) are mixed to form a clear aqueous solution. Sodium acetate (15g) and ethylenediamine monohydrate (50mL) are added. The mixture is stirred at 1000rpm for 30 minutes and then transferred to a high-pressure reactor. The reaction is carried out at 200℃ for 8 hours. After cooling to room temperature, the mixture is centrifuged at 8000rpm for 3 minutes, washed 4 times with ethanol, and dried at 60℃ for 6 hours to obtain MNPs-2.

[0063] The method for obtaining ink nanoparticles (CINPs) from cuttlefish ink sacs is as follows: Fresh cuttlefish are dissected to obtain ink sacs. A simple differential centrifugation method is used, centrifuging at 3000 r / min for 5 min to remove large particles, followed by centrifugation at 15000 r / min for 10 min at 4℃, removal of the supernatant, and freeze-drying at 4℃ for 5 h to obtain CINPs.

[0064] Instruments used: Inverted optical microscope (XD, Ningbo Sunny Instrument Co., Ltd., China); Scanning electron microscope (SEM, S-4800, Hitachi Co., Ltd., Japan); X-ray diffractometer (XRD, Bruker D8 Advance X-ray diffractometer); Zeta potential analyzer (Brookhaven Instruments Corporation, USA); Vibrating sample magnetometer (VSM, Physical Characterization System Model 6000, Quantum Design, Inc., USA); Infrared spectrometer (INVENIO S, Bruker); Contact angle meter (Dataphysics-OCA20, Germany); Inductively coupled plasma atomic emission spectrometer (Agilent, 5800, USA); High-performance liquid chromatograph (Prominence Plus). LC-20A (Shimadzu, Japan), equipped with a binary LC-20AD pump, SIL-20AC autosampler, CTO-20A column oven, DGU-20A degasser, SPD-20A UV detector; Hisep C18 column (250mm × 4.6mm id, 5μm).

[0065] Example 1

[0066] The structure, morphology, and other physicochemical properties of the first type of nano-iron oxide particles (MNPs-1) were characterized using scanning electron microscopy, X-ray diffraction analysis, Zeta potential analysis, vibrating sample magnetometer, infrared spectroscopy, and contact angle measurement. The results are as follows: Figure 1 As shown. Figure 1 a indicates that the particle size of MNPs-1 is 60-450 nm; Figure 1 b proves that MNPs-1 is pure iron(III) oxide; Figure 1 c indicates that its surface charge is 52.3 mV; Figure 1 d indicates that the saturation magnetization of MNPs-1 is 76.4 emu / g; Figure 1 e indicates that MNPs-1 has hydrophilic properties.

[0067] The morphology of ink sac nanoparticles (CINPs) in cuttlefish ink sacs was characterized using scanning electron microscopy, and the results are as follows: Figure 2 As shown, CINPs are uniformly sized spheres with an average particle size of 100 nm. The surface charge is approximately -22 mV (ACS Nano, 2019, 13, 8, 8618–8629).

[0068] MNPs-1 and CINPs were mixed to prepare an MNPs-1 concentration of 0.05 mg / mL. –1 The concentration of CINPs was 0.01 mg·mL. –1 A mixed aqueous solution. Vortex for 1 minute to fully mix the two colloidal particles, then let stand for 5 minutes. Figure 3 As shown, under the influence of a magnetic field, the two completely separate, indicating that they have successfully combined to form a magnetic adsorbent. The magnet used is a circular N52 type magnet with a diameter of 3cm, and the same applies below.

[0069] A 100 ppm concentration of benvitide standard was prepared and detected by high-performance liquid chromatography-ultraviolet (HPLC-UV). The results are as follows: Figure 4 The chromatographic peak area was A0 = 6643888.202, and the retention time was 7.783 min. The chromatographic conditions were: column temperature 26℃; mobile phase: acetonitrile-ammonium formate buffered aqueous solution (5 mM) (75:25, V:V); flow rate: 0.5 mg / mL. –1 The injection volume was 5 μL; the detection wavelength was 315 nm. The same applies below.

[0070] Prepare a mixed aqueous solution of MNPs-1 / CINPs / benvimod, wherein the concentration of MNPs-1 is 0.05 mg·mL. –1 The concentration of CINPs was 0.01 mg·mL. –1 The concentration of benvitimide was 100 ppm. The mixed solution was vortexed for 1 min, shaken for 10 min, magnetically aspirated for 2 min, and the supernatant was collected. After filtering through a 0.22 μm filter, the supernatant was added to a HPLC vial and subsequently subjected to high-performance liquid chromatography-UV detection. The results are as follows: Figure 4 The chromatographic peak area is A = 0. The adsorption efficiency is calculated to be 100% according to formula (1).

[0071] The adsorption efficiency is calculated as follows:

[0072]

[0073] A0 represents the chromatographic peak area of ​​benvimod before adsorption, and A represents the chromatographic peak area of ​​benvimod after adsorption. The adsorption efficiency of the magnetic adsorbent is calculated to be 100%.

[0074] Prepare a mixed aqueous solution of CINPs / benvimod, wherein the concentration of CINPs is 0.01 mg·mL. –1 The concentration of benvitide was 100 ppm. High-performance liquid chromatography-ultraviolet detection was performed using the method described above, and the results are as follows: Figure 4 As shown. The chromatographic peak area is 0. The adsorption efficiency is 100%.

[0075] Increase the concentration of the analyte:

[0076] The 350 ppm concentration of benvitide standard was analyzed by high-performance liquid chromatography-ultraviolet detection using the method described above. The results are as follows: Figure 5 The chromatographic peak area was A0 = 21360548.674, and the retention time was 8.059 min.

[0077] A mixed aqueous solution of MNPs-1 / CINPs / benvimod was prepared according to the above method, and the concentration of benvimod was increased to 350 ppm. Subsequently, high-performance liquid chromatography-ultraviolet detection was performed, and the results are as follows: Figure 5 The chromatographic peak area is A = 7617867.318. The adsorption efficiency of the magnetic adsorbent, calculated using formula (1), is 64.34%.

[0078] Prepare a mixed aqueous solution of CINPs / benvimod with a CINPs concentration of 0.01 mg / mL. –1 The concentration of benvitide was 350 ppm. After processing according to the above method, high-performance liquid chromatography-ultraviolet detection was performed, and the results were as follows. Figure 5 As shown, the chromatographic peak area A = 10315241.094. The adsorption efficiency is 51.71%.

[0079] The above results demonstrate that preparing magnetic adsorbents using the physical blending method does not affect the adsorption performance of the adsorbent. The addition of magnetic materials synergistically enhances the adsorption efficiency with the adsorbent.

[0080] The morphological characteristics of the physical mixture of CINPs and MNPs-1 were characterized and analyzed using scanning electron microscopy. The results are as follows: Figure 6 As shown. Comparative analysis shows that after physical mixing, MNPs-1 nanoparticles and CINPs nanoparticles aggregate together, while the overall morphology and particle size distribution of CINPs microspheres are similar to those of pure CINPs (…). Figure 2 Compared to CINPs, it remained stable. This result confirms that the interaction between MNPs-1 and CINPs microspheres is purely physical adsorption and does not cause any structural changes in the adsorbent material CINPs.

[0081] Example 2

[0082] The morphology and surface properties of graphene microsheets were characterized using an inverted optical microscope and a Zeta potential analyzer. The results are as follows: Figure 7 As shown. Figure 7 a indicates that the graphene microplates have a two-dimensional sheet-like structure with a particle size of 2-20 μm; Figure 7 b indicates that its surface charge is -20.9mV.

[0083] MNPs-1 was mixed with graphene microsheets (using anhydrous ethanol) to prepare a solution with a concentration of 0.5 mg / mL for both MNPs-1 and graphene microsheets.–1 A mixed solution. Vortex for 10 minutes to thoroughly mix the two colloidal particles, then let stand for 10 minutes. Figure 8 As shown in figure a. Under the influence of a magnetic field, the two did not achieve complete co-separation, and some residue remained ( Figure 8 b, not fully clarified), indicates that electrostatic repulsion is dominant at this time.

[0084] A NaCl aqueous solution was added to the above mixed solution to make the NaCl concentration 0.1M. The solution was vortexed for 2 minutes to fully mix the two colloidal particles. After standing for 5 minutes, the obtained magnetic adsorbent was collected using an external magnetic field. The results are as follows: Figure 8 As shown in c, the solution above is completely clear, indicating that the two have successfully combined to form a magnetic adsorbent.

[0085] The morphological characteristics of graphene microsheets before and after physical mixing with MNPs-1 were characterized and analyzed using scanning electron microscopy. The results are as follows: Figure 9 As shown. Comparative analysis shows that after physical mixing ( Figure 9 a) MNPs-1 nanoparticles are attached to the surface of graphene microsheets, while the overall morphology of the graphene microsheets differs from that of unmixed pure graphene microsheets. Figure 9 b) Compared to the previous result, it remained stable. This result confirms that the interparticle interaction between MNPs-1 and the graphene microsheets did not cause structural changes in the graphene.

[0086] Example 3

[0087] The structure, morphology, and other physicochemical properties of nano-Fe3O4 particles (Si-MPs) coated with silica were characterized, and the results are as follows: Figure 10 As shown. Figure 10 a indicates that the particle size of Si-MPs is 500 nm; Figure 10 b proves that Si-MPs is a composite material of silicon dioxide and iron oxide; Figure 10 c indicates that its surface charge is -65.6mV; Figure 10 d indicates that the saturation magnetization of Si-MPs is 48.1 emu / g; Figure 10 e indicates that Si-MPs have hydrophilic properties.

[0088] Si-MPs were mixed with graphene microsheets (using deionized water as the solvent, the same below) to prepare a solution with a concentration of 0.5 mg·mL for both Si-MPs and graphene microsheets. –1 A mixed aqueous solution was prepared. After vortexing for 10 minutes to fully mix the two colloidal particles, the mixture was allowed to stand for 10 minutes to test their ability to directly prepare magnetic adsorbents through physical blending in aqueous solution. Figure 11 As shown, the two did not exhibit good coordination. Under the influence of a magnetic field, they also did not move together. Figure 12This indicates that electrostatic repulsion is dominant at this time.

[0089] Effect of electrolyte concentration on the preparation of magnetic adsorbents:

[0090] Different concentrations of NaCl aqueous solution were added to the above mixed aqueous solution, controlling the NaCl concentration in the mixed aqueous solution to be (a) 0.1M, (b) 0.5M, and (c) 1M, respectively. After vortexing for 2 minutes to fully mix the two colloidal particles, the mixture was allowed to stand for 5 minutes, and the macroscopic co-separation effect of the two particles was observed under an external magnetic field. The results are as follows: Figure 13 As shown in a, 13b, and 13c, after the electrolyte concentration increased, the two types of particles successfully achieved co-magnetic separation, indicating that they successfully combined to form a magnetic adsorbent.

[0091] The key mechanism of this invention lies in the colloidal coagulation effect based on the DLVO theory, where the interparticle interaction is a fundamental principle. This theory clarifies that the interaction between colloids (particle adhesion) is primarily influenced by van der Waals forces and electrostatic repulsion between colloidal particles. In the aforementioned system, before the addition of the electrolyte, the electrostatic repulsion between particles is relatively strong, making it difficult for particles to adhere and form a magnetic adsorbent. However, as the electrolyte concentration in the system increases, the spatial shielding effect caused by ion diffusion weakens the electrostatic repulsion, thereby enhancing the overall coagulation effect and making it easier for particles to adhere and form a magnetic adsorbent.

[0092] Example 4

[0093] The morphology and surface properties of monodisperse carboxylated polystyrene (COOH-PS) microspheres were characterized using an inverted optical microscope and a Zeta potential analyzer. The results are as follows: Figure 14 As shown. Figure 14 a indicates that the monodisperse carboxylated polystyrene microspheres are spherical in shape with uniform size and a particle size of 3 μm; Figure 14 b indicates that its surface charge is -73.7mV.

[0094] Si-MPs and COOH-PS microspheres were mixed to prepare a mixture with a concentration of 0.5 mg·mL for both Si-MPs and COOH-PS microspheres. –1 A mixed aqueous solution was prepared. After vortexing for 1 minute to fully mix the two colloidal particles, the mixture was allowed to stand for 3 minutes. The ability of these particles to be directly prepared into magnetic adsorbents through physical blending in aqueous solution was then tested. The results showed that they could not move together to achieve co-separation.

[0095] NaCl aqueous solution was added to the above mixed aqueous solution to make the NaCl concentration 1M. After vortexing for 2 minutes to fully mix the two colloidal particles, the mixture was allowed to stand for 5 minutes. The macroscopic co-separation effect of the two particles was observed under an external magnetic field. The results showed that the two particles successfully achieved co-magnetic separation, indicating that they successfully combined to form a magnetic adsorbent.

[0096] Example 5

[0097] The structure, morphology, and other physicochemical properties of the third type of nano-iron oxide particles (MNPs-3) were characterized, and the results are as follows: Figure 15 As shown. Figure 15 a indicates that the particle size of MNPs-3 is 10-30 nm; Figure 15 b proves that MNPs-3 is a pure iron oxide material; Figure 15 c indicates that its surface charge is -56.3mV; Figure 15 d indicates that the saturation magnetization of MNPs-3 is 61.0 emu / g; Figure 15 e indicates that MNPs-3 has hydrophilic properties.

[0098] MNPs-3 was mixed with graphene microflakes to prepare a solution where both MNPs-3 and graphene microflakes had a concentration of 0.5 mg·mL. –1 The mixed aqueous solution was vortexed for 1 minute to fully mix the two colloidal particles, then allowed to stand for 3 minutes. The time sequence diagram of the collection process is shown below. Figure 16 As shown, the two did not achieve a joint separation.

[0099] Add KCl aqueous solution to the above mixed aqueous solution, controlling the KCl concentration in the solution to 0.5M. Vortex for 2 minutes to fully mix the two colloidal particles, then let stand for 5 minutes. Observe the macroscopic co-separation effect of the two particles under an external magnetic field. The results show that after the electrolyte concentration increases, the two particles successfully achieve co-magnetic separation, indicating that they have successfully combined to form a magnetic adsorbent.

[0100] Comparative Example 1

[0101] Preparation method of magnetic adsorbent:

[0102] MNPs-1 and graphene microflakes were formulated to a concentration of 0.5 mg / mL for both MNPs-1 and graphene microflakes. –1 A mixed aqueous solution was prepared. The two particles were vortexed for 2 minutes to ensure thorough mixing. After standing for 5 minutes, the magnetic adsorbent was collected under an external magnetic field. The timeline of the collection process is shown in the figure. Figure 17 As shown.

[0103] According to the DLVO theory, the magnitudes of van der Waals forces and electrostatic forces between colloidal particles are also related to the polarity of the solvent. The particle aggregation effect is not entirely the same in different solvents, thus potentially leading to inconsistent experimental phenomena, but these can all be adjusted by changing the electrolyte concentration in the system.

[0104] The microscopic dynamics of two colloidal particles before and after the application of a magnetic field were observed using an inverted optical microscope. The results are as follows: Figure 18As shown, with the application of a magnetic field, the number of colloidal particles in the microscope field of view gradually decreased, indicating that non-magnetic particles moved together with magnetic particles under the attraction of the magnetic field, proving that the magnetic adsorbent was successfully prepared.

[0105] The morphological characteristics of the physical mixture of graphene microsheets and MNPs-1 were characterized and analyzed using scanning electron microscopy. The results are as follows: Figure 19 As shown. Comparative analysis indicates that after physical mixing, MNPs-1 nanoparticles adhere to the surface of graphene microsheets, while the overall morphology of the graphene microsheets differs from that of unmixed pure graphene microsheets. Figure 9 b) Compared to the previous result, it remained stable. This result confirms that the interparticle interaction between MNPs-1 and graphene microsheets did not cause structural changes in graphene. Effect of magnetic particle concentration on the preparation of magnetic adsorbents:

[0106] The concentrations of MNPs-1 were adjusted to 0.25, 0.75, and 1 mg·mL, respectively. –1 The concentration of graphene microflakes was 0.5 mg·mL. –1 After vortexing for 1 minute to fully mix the two types of particles, the mixture was allowed to stand for 5 minutes. The macroscopic collection timeline is shown below. Figure 20 As shown, the higher the proportion of magnetic particles, the stronger the magnetism of the magnetic adsorbent and the faster the particle recovery rate.

[0107] Comparative Example 2

[0108] The morphology and surface properties of monodisperse polystyrene (PS) microspheres were characterized using an inverted optical microscope and a Zeta potential analyzer. The results are as follows: Figure 21 As shown. Figure 21 a indicates that the monodisperse polystyrene microspheres have a spherical structure and a particle size of 10 μm; Figure 21 b indicates that its surface charge is -61.6mV.

[0109] 10 μm PS microspheres were mixed with MNPs-1 to prepare a solution with a concentration of 0.5 mg·mL for both PS and MNPs-1 particles. –1 A mixed aqueous solution was prepared. After vortexing for 1 minute to thoroughly mix the two particles, the mixture was allowed to stand for 3 minutes to test their ability to directly prepare magnetic adsorbents through physical blending in aqueous solution. Figure 22 As shown, numerous small magnetic particles adhere to the surface of monodisperse polystyrene microspheres, exhibiting excellent bonding. Under the influence of a magnetic field, they can move together to achieve co-separation. Figure 23 This indicates that van der Waals force was dominant at this time.

[0110] The morphological characteristics of the physical mixture of PS microspheres and MNPs-1 were characterized and analyzed using scanning electron microscopy. The results are as follows: Figure 24 As shown. Comparative analysis shows that after physical mixing ( Figure 24 MNPs-1 nanoparticles are uniformly attached to the surface of PS microspheres, while the overall morphology and particle size distribution of the PS microspheres are similar to those of pure PS microspheres. Figure 21 a) Remains stable compared to the previous result. This result confirms that the interparticle interaction between MNPs-1 and PS microspheres did not cause structural changes in the adsorbent material.

[0111] Comparative Example 3

[0112] The morphology and surface properties of silica gel were characterized using an inverted optical microscope and a Zeta potential analyzer. The results are as follows: Figure 25 As shown. Figure 25 a indicates that the silica gel has an irregular sheet-like structure with a particle size of approximately 40 μm; Figure 25 b indicates that its surface charge is -0.6mV, which is close to electrical neutrality.

[0113] The graphene microsheets in Comparative Example 1 were replaced with silica gel, which was then mixed with MNPs-1 to prepare a solution where both the graphene microsheets and silica gel had a concentration of 0.5 mg·mL. –1 A mixed aqueous solution. After vortexing for 2 minutes to fully mix the two types of particles, let it stand for 3 minutes. Under the influence of a magnetic field, they can move together and achieve co-separation.

[0114] Comparative Example 4

[0115] The graphene microsheets in Comparative Example 1 were replaced with monodisperse carboxylated polystyrene (COOH-PS) microspheres, and MNPs-1 were mixed to prepare a mixture with MNPs-1 and COOH-PS microspheres at a concentration of 0.5 mg·mL. –1 A mixed aqueous solution. After vortexing for 1 minute to fully mix the two types of particles, and then letting it stand for 3 minutes, they can move together under the influence of a magnetic field to achieve co-separation.

[0116] Comparative Example 5

[0117] In Comparative Example 3, MNPs-1 were replaced with nano-Fe3O4 particles (Si-MPs) coated with silica. These were then mixed with silica gel to prepare a solution with Si-MPs and silica gel particles at concentrations of 0.5 mg·mL⁻¹. –1 A mixed aqueous solution. After vortexing for 1 minute to fully mix the two types of particles, the mixture was allowed to stand for 4 minutes. Under the influence of a magnetic field, they moved together and achieved co-separation.

[0118] Comparative Example 6

[0119] The graphene microsheets in Comparative Example 1 were replaced with hydrophilic fumed silica nanoparticles, which were then mixed with MNPs-1 to prepare a solution with a hydrophilic fumed silica nanoparticle and MNPs-1 particle concentration of 0.5 mg·mL⁻¹. –1A mixed aqueous solution is vortexed for 1 minute to ensure thorough mixing of the two types of particles, and then allowed to stand for 3 minutes. Under the influence of a magnetic field, they can move together to achieve co-separation.

[0120] Comparative Example 7

[0121] The structure, morphology, and other physicochemical properties of the second type of nano-iron oxide particles (MNPs-2) were characterized, and the results are as follows: Figure 26 As shown. Figure 26 a indicates that the particle size of MNPs-2 is 30 nm; Figure 26 b proves that the MNPs-2 phase is pure iron(III) oxide; Figure 26 c indicates that its surface charge is 13.2 mV; Figure 26 d indicates that the saturation magnetization of MNPs-2 is 70.9 emu / g; Figure 26 e indicates that MNPs-2 has hydrophilic properties.

[0122] In Comparative Example 1, MNPs-1 was replaced with MNPs-2, which was then mixed with graphene microsheets to prepare a solution where both MNPs-2 and graphene microsheets had a concentration of 0.5 mg·mL. –1 The two particles were vortexed for 1 minute to ensure thorough mixing, and then allowed to stand for 4 minutes. Under the influence of a magnetic field, they moved together and were then co-separated.

[0123] Comparative Example 8

[0124] The graphene microsheets in Comparative Example 7 were replaced with monodisperse aminopolystyrene (NH2-PS) microspheres, which were then mixed with MNPs-2 to prepare a formulation in which the concentrations of both NH2-PS microspheres and MNPs-2 particles were 0.5 mg·mL. –1 The two particles were vortexed for 1 minute to ensure thorough mixing, and then allowed to stand for 3 minutes. Under the influence of a magnetic field, they moved together and were then co-separated.

[0125] According to the DLVO theory, interparticle interactions are mainly determined by van der Waals forces and electrostatic interactions. Factors influencing these interactions include particle material properties, particle size, surface charge, hydrophilicity / hydrophobicity, pH value, and electrolyte concentration. Table 1 shows the magnetic separation effects in aqueous solutions of magnetic adsorbents prepared from four types of nano-ferric oxide particles and eleven types of non-magnetic colloidal particles without added electrolyte. The inability to achieve co-separation indicates weak interparticle binding forces. Increasing the electrolyte concentration in the solution enhances interparticle binding forces and promotes co-separation, demonstrating the decisive role of electrolyte concentration.

[0126] Table 1

[0127]

[0128] Note: √ in the table indicates that the particles can be separated under a magnetic field; × indicates that they cannot be separated under a magnetic field.

[0129] The present invention can be realized by the types and concentrations of magnetic particles, non-magnetic particles, and salts, as well as the range of values ​​for solvents, etc., and examples are not listed here.

Claims

1. A universal method for preparing magnetic adsorbents based on physical blending, comprising the following steps: A mixed solution of magnetic colloidal particles and non-magnetic colloidal particles is prepared, and an aqueous solution of sodium or potassium salt is added; the two types of colloidal particles are thoroughly mixed and aggregated, and the magnetic adsorbent is collected by an external magnetic field after standing. The magnetic colloidal particles are one of Fe3O4, Fe2O3 or MnFe2O4; The non-magnetic colloidal particles are one of carbon-based materials, silicon-based materials, polymer-based materials, or bio-based materials; The carbon-based material is either graphene microsheets or multi-walled carbon nanotubes. The silicon-based material is one of silica gel, hydrophilic fumed nano silica, and hydrophobic fumed nano silica. The polymer-based material is one of monodisperse polystyrene microspheres, monodisperse carboxylated polystyrene microspheres, or monodisperse amino polystyrene microspheres. The bio-based material is nanoparticles from the ink sac of a cuttlefish.

2. The universal method for preparing magnetic adsorbents based on physical blending according to claim 1, characterized in that, The magnetic colloidal particles have a particle size range of 10 nm to 2 μm; and / or The particle size of the non-magnetic colloidal particles is between 10 nm and 100 μm.

3. The universal method for preparing magnetic adsorbents based on physical blending according to claim 1, characterized in that, The solvent for the mixed solution is one of water, ethanol, acetone, or acetonitrile.

4. The universal method for preparing magnetic adsorbents based on physical blending according to claim 1, characterized in that, The concentration of magnetic colloidal particles in the mixed solution is 0.1-5 mg·mL. –1 ; and / or The concentration of non-magnetic colloidal particles in the mixed solution is 0.05-5 mg·mL. –1 .

5. The universal method for preparing magnetic adsorbents based on physical blending according to claim 1, characterized in that, The sodium salt is sodium chloride or sodium nitrate, and the potassium salt is potassium chloride or potassium nitrate; and / or After adding the aqueous solution of the sodium or potassium salt, the concentration of the sodium or potassium salt in the resulting solution is 0.001-5 M.

6. The universal method for preparing magnetic adsorbents based on physical blending according to claim 1, characterized in that, The method for fully mixing the two colloidal particles is to use ultrasound or vortex for 1-10 minutes; the settling time is 5-10 minutes.

7. A magnetic adsorbent prepared by a universal method for preparing magnetic adsorbents based on physical blending as described in any one of claims 1-6.

8. The application of a magnetic adsorbent prepared by a universal method for preparing magnetic adsorbents based on physical blending as described in any one of claims 1-6 in the removal of Benvitimod.

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