Universal method for preparing magnetic adsorbent based on physical blending

Abstract

The invention belongs to the technical field of environmental functional materials and pollution remediation, and particularly relates to a universal method for preparing a magnetic adsorbent based on physical blending. The method comprises the following steps: mixing magnetic colloid particles and non-magnetic colloid particles in a solution, adding salt to adjust electrolyte concentration to induce colloid coagulation, uniformly mixing the particles by ultrasonic or vortex, standing, and collecting the obtained magnetic adsorbent by using an external magnetic field. The mechanism is characterized in that the interaction between particles is based on the colloid coagulation effect of the DLVO theory, and the relative magnitude of electrostatic repulsive force and Van der Waals attractive force is regulated and controlled by regulating and controlling the salt concentration, so that colloid coagulation is driven, and the magnetic adsorbent is formed. Complex chemical modification or high-temperature treatment is not needed, the original structure, adsorption performance and extraction performance of the adsorbent can be reserved, and the adsorbent is endowed with magnetic separation performance. Meanwhile, the method has the advantages of simplicity and convenience in operation, low cost, high universality and the like, and has a wide application prospect in the field of large-scale preparation of magnetic adsorbents.

Description

Technical Field

[0001] The present invention belongs to the technical field of environmental functional materials and pollution remediation, and specifically relates to a universal method for preparing a magnetic adsorbent based on physical blending. Background Art

[0002] Magnetic adsorbents typically consist of magnetic particles and an adsorbent, with the magnetic particles serving as the adsorbent's carrier. These magnetic particles possess high magnetic permeability and magnetic saturation, generating strong magnetic fields that enable the adsorption and separation of substances. Magnetic adsorbents are widely used in water treatment, environmental protection, biomedicine, and the food industry. They hold broad application prospects in water treatment, where they can remove harmful substances such as heavy metal ions and organic pollutants from water, improving the safety and cleanliness of water quality. In environmental protection, magnetic adsorbents can be used for industrial wastewater treatment and soil remediation. By adsorbing and removing pollutants from the environment, they contribute to protecting the ecological environment and human health. In the biomedical field, they can be used for targeted drug delivery, cell separation, and purification. The magnetic responsiveness of magnetic adsorbents enables precise drug release at specific locations and efficient cell separation. In the food 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 materials, including graphene / graphene oxide, carbon nanotubes, metal-organic frameworks, covalent organic frameworks, molecularly imprinted materials, nanocomposites, and polymers. However, the complex and time-consuming synthesis of these magnetic adsorbents precludes large-scale production, limiting their development in practical applications. The inventors of the present invention previously obtained magnetic molecularly imprinted adsorbents by physically mixing and vortexing ferrosoferric 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 adsorbent's excellent extraction performance. However, because the underlying principles of this method have not yet been revealed, it is currently limited to specific particle systems and cannot be universally applied by adjusting other parameters. This has seriously hindered its use and development in the preparation of magnetic adsorbents. Summary of the Invention

[0004] The purpose of the present invention is to provide a universal method for preparing magnetic adsorbents based on physical blending, which has the characteristics of simple operation, controllable conditions, low cost, etc., and will not destroy the structural properties of the adsorbent itself.

[0005] In order to achieve the above purpose, the technical solutions adopted are as follows:

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

[0007] The magnetic colloidal particles and the non-magnetic colloidal adsorbent are prepared into a mixed solution, and an aqueous solution of sodium salt or potassium salt is added; the two colloidal particles are fully mixed and precipitated, and after standing, the obtained magnetic adsorbent is collected using an external magnetic field.

[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 nano-silica, and hydrophobic fumed nano-silica (preferably silica gel); and / or

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

[0013] The biological material is nanoparticles in the ink sac of cuttlefish.

[0014] Furthermore, the particle size of the magnetic colloidal particles is in the 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 10 nm-100 μm (preferably 200 nm-10 μm).

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

[0017] Furthermore, the concentration of the magnetic colloidal particles in the mixed solution is 0.1-5 mg·mL –1 (Preferably 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 (Preferably 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 the aqueous solution of the sodium salt or potassium salt is added, the concentration of the sodium salt or potassium salt in the obtained solution is 0.001-5M.

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

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

[0023] The present invention also provides the use of the magnetic adsorbent prepared by the universal method for preparing the magnetic adsorbent based on physical blending in removing benvimod.

[0024] According to the universal method for preparing magnetic adsorbents based on physical blending, the ratio of magnetic material to non-magnetic material in the magnetic adsorbent can be adjusted as needed by controlling the concentration of magnetic colloid particles. The higher the proportion of magnetic colloid particles, the stronger the magnetic adsorbent and the faster the particle recovery rate; the higher the proportion of non-magnetic colloid particles, the better the adsorption effect of the magnetic adsorbent.

[0025] By controlling the electrolyte concentration of the system, the van der Waals force between particles can be increased, and the coagulation and bonding of different particle systems can be achieved.

[0026] The mechanism of the present invention is characterized by the interparticle interaction being a colloidal coagulation effect based on the DLVO theory. This is primarily influenced by the van der Waals attraction and electrostatic repulsion between colloidal particles. As the electrolyte concentration in the system increases, the electrostatic repulsion is weakened due to steric shielding, thereby enhancing the coagulation effect.

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

[0028] The present invention provides a universal method for preparing magnetic adsorbents based on a physical blending method, 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 the present invention is applicable to magnetic and non-magnetic materials with different physical and chemical properties (including surface charge, surface functional groups, hydrophilicity and hydrophobicity, particle size, etc.).

[0030] The universal method of preparing a magnetic adsorbent based on physical blending of the present invention can impart magnetic characteristics to the solid-phase adsorbent while maintaining good adsorption performance and extraction capacity of the adsorbent. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1: Characterization of MNPs-1 in Example 1: a scanning electron microscopy image, b X-ray diffraction pattern, c zeta potential diagram, d magnetic saturation intensity curve, e contact angle;

[0032] Figure 2 : Scanning electron microscopy image of CINPs in Example 1;

[0033] Figure 3 : In Example 1, a macroscopic image of the magnetic adsorbent was collected under a magnetic field;

[0034] Figure 4 : In Example 1, the chromatogram when the concentration of benvimod is 100 ppm;

[0035] Figure 5 : In Example 1, the chromatogram when the concentration of benvimod is 350 ppm;

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

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

[0038] Figure 8 : In Example 2, a macrograph of MNPs-1 and graphene microsheets without applying a magnetic field when no NaCl solution was added, b macrograph of the magnetic adsorbent collected under a magnetic field when no NaCl solution was added, c macrograph of the magnetic adsorbent collected under a magnetic field, and the NaCl concentration was 0.1 M;

[0039] Figure 9 : Scanning electron micrographs 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 microscopy 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 in Example 3 when no magnetic field is applied;

[0042] Figure 12 : Microscopic dynamics of Si-MPs and graphene microsheets when a magnetic field is applied in Example 3; H represents the magnetic field, and the arrows point to the direction of the magnetic field;

[0043] Figure 13 : In Example 3, a timing diagram 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 microscopy image, b X-ray diffraction pattern, c zeta potential diagram, d magnetic saturation intensity curve, e contact angle;

[0046] Figure 16 : Macroscopic timing diagram of collecting magnetic adsorbent under a magnetic field when no KCl aqueous solution is added in Example 5;

[0047] Figure 17 : In Comparative Example 1, a macroscopic timing diagram of collecting magnetic adsorbent under a magnetic field;

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

[0049] Figure 19 : Scanning electron micrograph of the graphene microsheets physically mixed with MNPs-1 in Comparative Example 1;

[0050] Figure 20 : In Comparative Example 1, the macroscopic time series of the magnetic adsorbent at different MNPs-1 concentrations were collected under a magnetic field, a0.25 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 in comparative example 2 when no magnetic field was applied;

[0053] Figure 23 : Microscopic dynamics of MNPs-1 and PS microspheres in the presence of a magnetic field in Comparative Example 2. H represents the magnetic field, and the arrow indicates the direction of the magnetic field.

[0054] Figure 24 : Scanning electron micrograph 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 microscopy image, b X-ray diffraction pattern, c zeta potential diagram, d magnetic saturation intensity curve, e contact angle. DETAILED DESCRIPTION

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

[0058] Unless otherwise specified, the materials and reagents in the present invention are commercially available conventional materials and reagents.

[0059] In the embodiment:

[0060] Surface-coated ferroferric oxide nanoparticles (Si-MPs, purchased from Suzhou Nano Micro Technology Co., Ltd., with a particle size of 500 nm); the first type of ferroferric oxide nanoparticles (MNPs-1, with a particle size of 60-450 nm); the second type of ferroferric oxide nanoparticles (MNPs-2, with a particle size of 30 nm); the third type of ferroferric oxide nanoparticles (MNPs-3, purchased from Shanghai MacLean Biochemical Technology Co., Ltd., with a particle size of 10-30 nm); silica gel (purchased from Qingdao Xinlida Silica Gel Co., Ltd., with an irregular flaky structure and a particle size of approximately 40 μm); hydrophilic vapor-phase nanosilica gel (purchased from Shanghai Roen Reagent, with an irregular flaky structure and a particle size of approximately 50-100 μm); hydrophobic vapor-phase nanosilica gel (purchased from Shanghai Roen Reagent, with an irregular flaky structure and a particle size of approximately 10-20 μm); graphene microsheets (purchased from Shanghai TCI Chemicals (Tianjin) Co., Ltd. (two-dimensional lamellar structure, particle size 2-20 μm); monodisperse polystyrene microspheres (purchased from Tianjin Daye Technology Co., Ltd., spherical structure, 500 nm; 3 μm; 10 μm); monodisperse carboxyl polystyrene microspheres (purchased from Tianjin Daye Technology Co., Ltd., spherical, particle size 3 μm); monodisperse amino polystyrene microspheres (purchased from Tianjin Daye Technology Co., Ltd., spherical, particle size 3 μm); multi-walled carbon nanotubes (purchased from Shanghai MacLean Biochemical Technology Co., Ltd., particle size 60-100 nm, length 5-15 μm); copper nitrate trihydrate (purchased from Shanghai MacLean Biochemical Technology Co., Ltd.); cuttlefish ink sac nanoparticles (CINPs, regular spherical, average particle size 100 nm); tapinarof (purchased from Shanghai MacLean Biochemical Technology Co., Ltd.);

[0061] The first method for preparing ferroferric oxide nanoparticles (MNPs-1) is as follows: FeCl3·6H2O (1.35 g) and ethylene glycol (40 mL) were mixed to form a clear aqueous solution, sodium acetate (3.6 g) and polyethylene glycol (MW=2000, 1.0 g) were added, and the mixture was stirred at 1000 rpm for 30 minutes. The mixture was then transferred to an autoclave and reacted at 200°C for 8 hours. After cooling to room temperature, the mixture was centrifuged at 8000 rpm for 3 minutes, washed with ethanol and water four times respectively, and dried at 60°C for 6 hours to obtain MNPs-1.

[0062] The second method for preparing ferroferric oxide nanoparticles (MNPs-2) is as follows: FeCl3·6H2O (5 g) and ethylene glycol (100 mL) were mixed to form a clear aqueous solution, sodium acetate (15 g) and ethylenediamine monohydrate (50 mL) were added, and the mixture was stirred at 1000 rpm for 30 minutes. The mixture was then transferred to an autoclave and reacted at 200°C for 8 hours. After cooling to room temperature, the mixture was centrifuged at 8000 rpm for 3 minutes, washed with ethanol four times, and dried at 60°C for 6 hours to obtain MNPs-2.

[0063] Cuttlefish ink sac nanoparticles (CINPs) were obtained by dissecting fresh cuttlefish to obtain the ink sac. The CINPs were then obtained by simple differential centrifugation at 3000 rpm for 5 minutes to remove large particles. The resulting mixture was then centrifuged at 15000 rpm for 10 minutes at 4°C. The supernatant was removed and freeze-dried at 4°C for 5 hours.

[0064] The instruments used were: 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 optical emission spectrometer (Agilent, 5800, USA); high performance liquid chromatograph (Prominence Plus The HPLC-MS / MS instrument was used (LC-20A, Shimadzu, Japan), equipped with a binary LC-20AD pump, a SIL-20AC autosampler, a CTO-20A column oven, a DGU-20A degasser, and a SPD-20A UV detector; and a Hisep C18 column (250 mm × 4.6 mm id, 5 μm).

[0065] Example 1

[0066] The structure, morphology and other physicochemical properties of the first nano-iron oxide particles (MNPs-1) were characterized by scanning electron microscopy, X-ray diffraction analyzer, Zeta potential analyzer, vibrating sample magnetometer, infrared spectrometer and contact angle meter. Figure 1 shown. Figure 1 a shows that the particle size of MNPs-1 is 60–450 nm; Figure 1 b proves that MNPs-1 is pure ferrosoferric oxide; Figure 1 c shows that its surface charge is 52.3 mV; Figure 1 d shows that the saturation magnetization of MNPs-1 is 76.4emu / g; Figure 1 e indicates that MNPs-1 is hydrophilic.

[0067] The morphology of cuttlefish ink sac nanoparticles (CINPs) was characterized by scanning electron microscopy. Figure 2 As shown in Figure 2, CINPs are uniformly spherical with an average particle size of 100 nm and a surface charge of approximately -22 mV (ACS Nano, 2019, 13, 8, 8618–8629).

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

[0069] A 100 ppm Benvimod standard sample was prepared and subjected to HPLC-UV detection. 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°C; mobile phase acetonitrile-ammonium formate buffered saline solution (5 mM) (75:25, V:V), flow rate 0.5 mg·mL –1 The injection volume was 5 μL and the detection wavelength was 315 nm.

[0070] Prepare a mixed aqueous solution of MNPs-1 / CINPs / benvimod, where the concentration of MNPs-1 is 0.05 mg mL –1 , CINPs concentration was 0.01 mg·mL –1 The concentration of Benvimod was 100 ppm. The mixed solution was vortexed for 1 min, shaken for 10 min, and magnetically aspirated for 2 min. The supernatant was aspirated, filtered with a 0.22 μm filter head, and added to a liquid phase vial. HPLC-UV detection was then performed. The results were as follows: Figure 4 The chromatographic peak area is A = 0. The adsorption efficiency calculated according to formula (1) is 100%.

[0071] The adsorption efficiency is calculated as follows:

[0072]

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

[0074] Prepare a CINPs / benvimod mixed aqueous solution with a CINPs concentration of 0.01 mg mL –1 , the concentration of Benvimod was 100ppm. HPLC-UV detection was performed according to the above method, and the results were as follows Figure 4 As shown in the figure, the chromatographic peak area is 0. The adsorption efficiency is 100%.

[0075] Increasing analyte concentration:

[0076] The 350 ppm Benvimod standard sample was subjected to HPLC-UV detection according to the above method. Figure 5 The chromatographic peak area is A0=21360548.674, and the retention time is 8.059min.

[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. HPLC-UV detection was then performed, and the results were as follows: Figure 5 The chromatographic peak area is A = 7617867.318. According to formula (1), the adsorption efficiency of the magnetic adsorbent is calculated to be 64.34%.

[0078] Prepare CINPs / benvimod mixed aqueous solution with a CINPs concentration of 0.01 mg mL –1 , the concentration of Benvimod was 350ppm. After treatment according to the above method, HPLC-UV detection was performed, and the results were as follows Figure 5 As shown in the figure, the chromatographic peak area A = 10315241.094, and the adsorption efficiency is 51.71%.

[0079] These results demonstrate that the physical blending method for preparing magnetic adsorbents does not affect their adsorption performance. The addition of magnetic materials synergizes with the adsorbents to enhance adsorption efficiency.

[0080] Scanning electron microscopy was used to characterize the morphology of the CINPs and MNPs-1 mixtures. Figure 6 Comparative analysis showed that after physical mixing, MNPs-1 nanoparticles and CINPs nanoparticles aggregated together, while the overall morphology and particle size distribution of CINPs microspheres were similar to those of pure CINPs ( Figure 2 This result confirms that the adsorption between MNPs-1 and CINPs microspheres is only physical adsorption, and does not cause the structural change of the adsorbent 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. Figure 7 shown. Figure 7 a shows that the graphene microsheets have a two-dimensional sheet structure with a particle size of 2-20 μm; Figure 7 b shows that its surface charge is -20.9 mV.

[0083] MNPs-1 and graphene microsheets were mixed (the solvent was anhydrous ethanol) to prepare a concentration of 0.5 mg·mL for both MNPs-1 and graphene microsheets.–1 Vortex for 10 minutes to fully mix the two colloidal particles and then let it stand for 10 minutes. Figure 8 As shown in a. Under the action of the magnetic field, the two are not completely separated, and some residues remain ( Figure 8 b, complete clarification was not achieved), indicating that electrostatic repulsion dominates at this time.

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

[0085] Scanning electron microscopy was used to characterize the morphology of graphene microsheets before and after physical mixing with MNPs-1. Figure 9 As shown. Comparative analysis shows that after physical mixing ( Figure 9 a), MNPs-1 nanoparticles attached to the surface of graphene microsheets, and the overall morphology of graphene microsheets is similar to that of unmixed pure graphene microsheets ( Figure 9 This result confirms that the interparticle interaction between MNPs-1 and graphene microsheets does not cause structural changes in graphene.

[0086] Example 3

[0087] The structure, morphology and other physical and chemical properties of Fe3O4 nanoparticles coated with silica (Si-MPs) were characterized. Figure 10 shown. Figure 10 a shows that the particle size of Si-MPs is 500 nm; Figure 10 b proves that Si-MPs are a composite material of silicon dioxide and ferrosoferric oxide; Figure 10 c indicates that its surface charge is -65.6 mV; Figure 10 d shows that the saturation magnetization of Si-MPs is 48.1emu / g; Figure 10 e shows that Si-MPs are hydrophilic.

[0088] Si-MPs were mixed with graphene microsheets (the solvent was deionized water, the same below) to prepare a concentration of 0.5 mg·mL for both Si-MPs and graphene microsheets. –1 The two colloidal particles were vortexed for 10 minutes to fully mix and then allowed to stand for 10 minutes to test their ability to directly prepare magnetic adsorbents by physical blending in aqueous solution. Figure 11 As shown, the two do not show a good combination. Under the action of the magnetic field, they do not move together ( Figure 12), indicating that the electrostatic repulsion is dominant at this time.

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

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

[0091] The mechanism of the present invention is characterized by the interparticle interaction being a colloidal coagulation effect based on the DLVO theory. This theory explains that intercolloidal interactions (particle bonding) are primarily influenced by the van der Waals attraction and electrostatic repulsion between colloidal particles. In the aforementioned system, before the addition of electrolyte, the interparticle electrostatic repulsion is large, making it difficult for the particles to bond to form a magnetic adsorbent. However, when 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 the particles to bond to form a magnetic adsorbent.

[0092] Example 4

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

[0094] Si-MPs were mixed with COOH-PS microspheres to prepare a concentration of 0.5 mg mL for both Si-MPs and COOH-PS microspheres. –1 The two colloidal particles were vortexed for 1 minute to thoroughly mix and then allowed to stand for 3 minutes to test their ability to directly prepare magnetic adsorbents by physical blending in aqueous solution. The results showed that they could not co-move to achieve co-separation.

[0095] A NaCl solution was added to the mixed aqueous solution to a 1 M NaCl concentration. The two colloidal particles were thoroughly mixed by vortexing for 2 minutes, then allowed to stand for 5 minutes. Macroscopic co-separation of the two particles was observed under an applied magnetic field. The results showed successful co-magnetic separation of the two particles, indicating that they had successfully combined to form a magnetic adsorbent.

[0096] Example 5

[0097] The structure, morphology and other physical and chemical properties of the third nano-iron tetroxide particles (MNPs-3) were characterized. Figure 15 shown. Figure 15 a shows that the particle size of MNPs-3 is 10–30 nm; Figure 15 b proves that MNPs-3 is pure ferroferric oxide material; Figure 15 c shows that its surface charge is -56.3 mV; Figure 15 d shows that the saturation magnetization of MNPs-3 is 61.0emu / g; Figure 15 e indicates that MNPs-3 is hydrophilic.

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

[0099] A KCl solution was added to the mixed aqueous solution, maintaining a KCl concentration of 0.5 M. The two colloidal particles were thoroughly mixed by vortexing for 2 minutes, then allowed to stand for 5 minutes. Macroscopic co-separation of the two particles was observed under an applied magnetic field. The results showed that as the electrolyte concentration increased, the two particles successfully achieved co-magnetic separation, indicating that they had successfully combined to form a magnetic adsorbent.

[0100] Comparative Example 1

[0101] Preparation method of magnetic adsorbent:

[0102] The concentrations of MNPs-1 and graphene microsheets were 0.5 mg·mL. –1 Vortex for 2 minutes to fully mix the two particles. After standing for 5 minutes, the magnetic adsorbent can be collected under an external magnetic field. The collection process timing diagram is shown in Figure 17 shown.

[0103] According to the DLVO theory, the magnitude of the van der Waals and electrostatic forces between colloidal particles is also related to the polarity of the solvent. The coagulation effect of particles in different solvents varies, resulting in inconsistent experimental phenomena. However, these can be adjusted by varying the electrolyte concentration in the system.

[0104] The microscopic dynamics of the two colloidal particles before and after the magnetic field was applied were observed using an inverted optical microscope. Figure 18As the magnetic field was applied, the number of colloidal particles in the microscope field gradually decreased, indicating that the non-magnetic particles and the magnetic particles moved together under the traction of the magnetic field, proving that the magnetic adsorbent was successfully prepared.

[0105] Scanning electron microscopy was used to characterize the morphology of the physical mixture of graphene microsheets and MNPs-1. Figure 19 Comparative analysis shows that after physical mixing, MNPs-1 nanoparticles are attached to the surface of graphene microsheets, while the overall morphology of graphene microsheets is different from that of unmixed pure graphene microsheets ( Figure 9 b) remained stable. This result confirms that the interaction between MNPs-1 and graphene microsheets did not cause structural changes in graphene.

[0106] The concentrations of MNPs-1 were adjusted to 0.25, 0.75, and 1 mg mL –1 , the concentration of graphene microsheets is 0.5 mg·mL –1 Vortex for 1 minute to fully mix the two particles and then let it stand for 5 minutes. The macroscopic collection timing diagram is shown in the figure. 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. Figure 21 shown. Figure 21 a shows that the monodisperse polystyrene microspheres have a spherical structure and a particle size of 10 μm; Figure 21 b shows that its surface charge is -61.6 mV.

[0109] 10 μm PS microspheres were mixed with MNPs-1 to prepare a concentration of 0.5 mg·mL for both PS and MNPs-1 particles. –1 The two particles were vortexed for 1 minute to fully mix and then allowed to stand for 3 minutes to test their ability to directly prepare magnetic adsorbents by physical blending in aqueous solution. Figure 22 As shown in the figure, many small magnetic particles are bonded to the surface of monodisperse polystyrene microspheres, and the two show good bonding. Under the action of the magnetic field, they can move together to achieve co-separation ( Figure 23 ), indicating that the van der Waals force is dominant at this time.

[0110] Scanning electron microscopy was used to characterize the morphology of the physical mixture of PS microspheres and MNPs-1. Figure 24 As shown. Comparative analysis shows that after physical mixing ( Figure 24 ), MNPs-1 nanoparticles were uniformly attached to the surface of PS microspheres, and the overall morphology and particle size distribution of PS microspheres were similar to those of pure PS microspheres ( Figure 21 This result confirms that the interparticle interaction between MNPs-1 and PS microspheres did not cause the structural change of 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. Figure 25 shown. Figure 25 a shows that the silica gel has an irregular flake structure and a particle size of about 40 μm; Figure 25 b shows that its surface charge is -0.6 mV, which is close to electrical neutrality.

[0113] The graphene microsheets in Comparative Example 1 were replaced with silica gel, which was mixed with MNPs-1 to prepare a mixture with a graphene microsheet and silica gel concentration of 0.5 mg·mL. –1 After vortexing for 2 minutes to fully mix the two particles, the solution was allowed to stand for 3 minutes. Under the action of the magnetic field, the two particles could move together and achieve co-separation.

[0114] Comparative Example 4

[0115] The graphene microsheets in Comparative Example 1 were replaced with monodisperse carboxyl polystyrene (COOH-PS) microspheres, which were mixed with MNPs-1 to prepare a mixture with a concentration of 0.5 mg·mL for both MNPs-1 and COOH-PS microspheres. –1 After vortexing for 1 minute to fully mix the two particles, the two particles were allowed to stand for 3 minutes. Under the action of the magnetic field, they could move together and achieve co-separation.

[0116] Comparative Example 5

[0117] The MNPs-1 in Comparative Example 3 was replaced with nano-Fe3O4 particles coated with silica (Si-MPs), which were mixed with silica gel to prepare Si-MPs and silica gel particles at concentrations of 0.5 mg·mL –1 The mixed aqueous solution was vortexed for 1 minute to fully mix the two particles and then allowed to stand for 4 minutes. Under the influence of the 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 nano-silica, which was mixed with MNPs-1 to prepare a hydrophilic fumed nano-silica and MNPs-1 particle concentration of 0.5 mg·mL –1The mixed aqueous solution was vortexed for 1 minute to fully mix the two particles and then allowed to stand for 3 minutes. Under the action of the magnetic field, they can move together to achieve co-separation.

[0120] Comparative Example 7

[0121] The structure, morphology and other physical and chemical properties of the second nano-iron tetroxide particles (MNPs-2) were characterized. Figure 26 shown. Figure 26 a shows that the particle size of MNPs-2 is 30 nm; Figure 26 b proves that the physical phase of MNPs-2 is pure ferrosoferric oxide; Figure 26 c shows that its surface charge is 13.2 mV; Figure 26 d shows that the saturation magnetization of MNPs-2 is 70.9emu / g; Figure 26 e indicates that MNPs-2 is hydrophilic.

[0122] The MNPs-1 in Comparative Example 1 was replaced with MNPs-2, which was mixed with graphene microsheets to prepare a mixture with a concentration of 0.5 mg·mL for both MNPs-2 and graphene microsheets. –1 The mixed aqueous solution was vortexed for 1 minute to fully mix the two particles and then allowed to stand for 4 minutes. Under the action of the magnetic field, the two particles moved together to achieve co-separation.

[0123] Comparative Example 8

[0124] The graphene microsheets in Comparative Example 7 were replaced with monodisperse amino polystyrene (NH2-PS) microspheres, which were mixed with MNPs-2 to prepare a particle concentration of 0.5 mg·mL for both NH2-PS microspheres and MNPs-2. –1 The mixed aqueous solution was vortexed for 1 minute to fully mix the two particles and then allowed to stand for 3 minutes. Under the action of the magnetic field, the two particles moved together to achieve co-separation.

[0125] According to the DLVO theory, interparticle interactions are primarily determined by van der Waals forces and electrostatic interactions. Factors influencing these two interactions include the particle's material properties, particle size, surface charge, hydrophilicity, pH value, and electrolyte concentration. Table 1 shows the magnetic separation effects of four nano-iron oxide particles and 11 non-magnetic colloidal particles in aqueous solution without the addition of electrolytes. Systems that fail to achieve co-separation indicate weak interparticle binding forces. Increasing the electrolyte concentration in the solution enhances interparticle binding forces, promoting co-separation and demonstrating the decisive role of electrolyte concentration.

[0126] Table 1

[0127]

[0128] Note: In the table, √: co-separated under magnetic field; ×: not co-separated under magnetic field.

[0129] The types and concentrations of magnetic particles, non-magnetic particles, salts, solvents and other parameters and range values ​​involved in the present invention can all achieve the present invention, and embodiments are not listed here one by one.

Claims

1. A universal method for preparing a magnetic adsorbent based on physical blending, comprising the following steps: Magnetic colloidal particles and non-magnetic colloidal particles are prepared into a mixed solution, and an aqueous solution of sodium salt or potassium salt is added; the two colloidal particles are fully mixed and precipitated, and after standing, the obtained magnetic adsorbent is collected using an external magnetic field.

2. The universal method for preparing a magnetic adsorbent based on physical blending according to claim 1, characterized in that: The magnetic colloidal particles are one of Fe3O4, Fe2O3 or MnFe2O4.

3. The universal method for preparing a magnetic adsorbent based on physical blending according to claim 1, characterized in that: The non-magnetic colloidal particles are one of carbon-based materials, silicon-based materials, polymer-based materials or bio-based materials; and / or The carbon-based material is one of graphene microsheets or multi-walled carbon nanotubes; and / or The silicon-based material is one of silica gel, hydrophilic fumed nano-silica, and hydrophobic fumed nano-silica; and / or The polymer-based material is one of monodisperse polystyrene microspheres, monodisperse carboxyl polystyrene microspheres or monodisperse amino polystyrene microspheres; The bio-based material is nanoparticles in cuttlefish ink sacs.

4. The universal method for preparing a magnetic adsorbent based on physical blending according to claim 1, characterized in that: The particle size of the magnetic colloidal particles is in the 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.

5. The universal method for preparing a magnetic adsorbent based on physical blending according to claim 1, characterized in that: The solvent of the mixed solution is one of water, ethanol, acetone and acetonitrile.

6. The universal method for preparing a magnetic adsorbent 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 .

7. The universal method for preparing a magnetic adsorbent 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 the aqueous solution of the sodium salt or potassium salt is added, the concentration of the sodium salt or potassium salt in the obtained solution is 0.001-5 M.

8. The universal method for preparing a magnetic adsorbent based on physical blending according to claim 1, characterized in that: The method for fully mixing the two colloidal particles is ultrasonication or vortexing for 1-10 minutes; and the standing time is 5-10 minutes.

9. A magnetic adsorbent prepared by the universal method for preparing a magnetic adsorbent based on physical blending as described in any one of claims 1 to 8.

10. Use of a magnetic adsorbent prepared by the universal method for preparing a magnetic adsorbent based on physical blending according to any one of claims 1 to 8 in removing benvimod.

Images