Preparation method and application of monodisperse magnetic microspheres modified with multi-carboxyl hyperbranched polyglycerol

Abstract

The invention discloses a method for preparing and applying a monodisperse magnetic microsphere modified by a multi-carboxyl hyperbranched polyglycerol, and the method comprises the following steps: S1, preparing polystyrene seed microspheres; S2, preparing PGMA-NH2 microspheres; S3, preparing magnetic PGMA microspheres; S4, preparing monodisperse magnetic microspheres modified by a multi-carboxyl hyperbranched polyglycerol. The monodisperse magnetic microspheres provided by the invention have good stability, acid and alkali resistance, and a large specific surface area, which are conducive to the attachment of dye molecules, and can realize efficient adsorption of cationic dyes, and can be applied to the removal of cationic dyes in wastewater. The monodisperse magnetic microspheres of the invention also have good magnetism, can be easily separated by applying a magnetic field, and the separated materials can also be recycled by eluting with an eluent, which can increase economic benefits.

Description

Technical Field

[0001] The invention relates to the field of adsorption materials, and in particular to a preparation method and application of monodisperse magnetic microspheres modified by multi-carboxyl hyperbranched polyglycerol. Background Art

[0002] With the continuous increase in the production of industrial products, wastewater containing various dyes flows into lakes, which not only hinders the growth and reproduction of aquatic organisms in the water, but also affects human health. Dyes are usually toxic and are mainly used in water-based coatings, plastics, fiber textiles and papermaking industries. Among different types of dyes, methylene blue (MB) and rhodamine 6G (R6G) are widely used in cotton, silk and inks because of their stable color and good water solubility. MB and R6G dyes can damage the lining of the respiratory tract, cause diarrhea, dizziness, vomiting, and may also damage the nervous system. In order to protect human health, dyes must be removed from water bodies.

[0003] At present, the treatment methods for dye wastewater include adsorption, precipitation, photocatalytic decolorization and biodegradation. Among them, adsorption is considered to be a simple and economical option because of its high treatment efficiency and simple steps. Various cheap adsorbents, such as porous silica, hydrogels and natural clays, have been studied for treating dyes in wastewater. However, the above materials need to be filtered or centrifuged to collect the adsorbed materials, which is cumbersome to operate. Magnetic polymer materials can enrich pollutants through an external magnetic field, which is more convenient and energy-saving than traditional methods such as filtration and centrifugation, and therefore are widely developed. The surface of porous polymers (polystyrene, polymethyl methacrylate, etc.) can be easily modified and grafted with functional groups, and magnetic particles can be simply introduced by in-situ magnetization.

[0004] Hyperbranched polymers have more surface functional groups than linear polymers, so hyperbranched polymer-modified magnetic polymer particles have a stronger adsorption capacity for pollutants. Hyperbranched polyglycerol (HPG) has attracted more and more attention and has been found to be used as a substitute for polyethylene glycol (PEG). HPG has more hydroxyl groups than PEG and is a water-soluble, easily available biocompatible material. In addition, there are more and more studies on the preparation of adsorbents using HPG as a raw material. Some reactive functional groups, such as amino, carboxyl, long-chain alkyl, oxime, etc., can be converted from hydroxyl groups through various chemical reactions.

[0005] Based on this, the present invention provides a monodisperse magnetic microsphere adsorbent modified by polycarboxyl hyperbranched polyglycerol to solve the above technical problems. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a preparation method and application of monodisperse magnetic microspheres modified with polycarboxyl hyperbranched polyglycerol in view of the deficiencies in the above-mentioned prior art.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is: in the first aspect of the present invention, a method for preparing monodisperse magnetic microspheres modified with polycarboxyl hyperbranched polyglycerol is provided, comprising the following steps:

[0008] S1, preparing a polystyrene seed microsphere suspension;

[0009] S2. Preparation of PGMA-NH2 microspheres:

[0010] The synthetic route is as follows:

[0011]

[0012] S2-1. Preparation of activated seed suspension:

[0013] Acetone, a swelling agent and an SDS aqueous solution are mixed and homogenized to obtain an activator emulsion; the polystyrene seed microsphere suspension prepared in step S1 is added to the activator emulsion and stirred to obtain an activated seed suspension;

[0014] S2-2. Preparation of porous PGMA microspheres:

[0015] Glycidyl methacrylate, divinylbenzene, a porogen, and benzoyl peroxide are added to an SDS aqueous solution and mixed, and then homogenized to obtain a monomer emulsion; the monomer emulsion is added to the activated seed suspension prepared in step S2-1 to swell, and then a PVA aqueous solution is added, and the mixture is heated and stirred for reaction, and after the reaction is completed, the mixture is centrifuged, and the solid product is extracted by a Soxhlet extraction method, and the extract is discarded, and the solid product is retained, washed, and vacuum dried to obtain porous PGMA microspheres;

[0016] S2-3, Amination of porous PGMA microspheres:

[0017] The porous PGMA microspheres are dispersed in deionized water containing polyamines, heated for reaction, filtered after the reaction is completed, and the solid product is washed and vacuum dried to obtain PGMA-NH2 microspheres;

[0018] S3. Preparation of magnetic PGMA microspheres:

[0019] The synthetic route is as follows:

[0020]

[0021] The PGMA-NH2 microspheres prepared in step S2 are added to an aqueous solution containing Fe2+ and Fe3+, stirred and heated, and aqueous ammonia is added to react. After the reaction is completed, the reaction is cooled, filtered, and the solid product is washed and vacuum dried to obtain magnetic PGMA microspheres: PGMA-M;

[0022] S4. Preparation of monodisperse magnetic microspheres modified with multi-carboxyl hyperbranched polyglycerol:

[0023] The synthetic route is as follows:

[0024]

[0025] The PGMA-M prepared in step S3 is mixed with triethylamine and an organic solvent, heated and stirred, and then glycidol is added dropwise. After the addition is completed, the solid product is filtered, washed, and vacuum dried to obtain PGMA-HPG microspheres;

[0026] PGMA-HPG microspheres, triethylamine and succinic anhydride are dispersed in an organic solvent, heated and stirred for reaction, and after the reaction, the magnetic product is separated by magnetic attraction to obtain monodisperse magnetic microspheres modified with multi-carboxyl hyperbranched polyglycerol: PGMA-HPG-COOH.

[0027] Preferably, step S1 specifically comprises:

[0028] Borax is dissolved in ultrapure water, and then refined styrene is added, heated and stirred under a nitrogen atmosphere, potassium persulfate is added to the resulting mixture, and then a chain transfer agent is added dropwise, and heated and stirred to react under a nitrogen atmosphere. After the reaction is completed, residual styrene is removed by water dialysis to obtain a polystyrene seed microsphere suspension.

[0029] Preferably, in step S1, the mass ratio of styrene, borax, potassium persulfate and chain transfer agent is 30:0.1-0.3:0.2-0.4:0.6-3, wherein the amount of ultrapure water added is such that the mass concentration of styrene in ultrapure water is 10-20%;

[0030] The chain transfer agent is a mixture of one or more of 2,4-diphenyl-4-methyl-1-pentene, 1-octanethiol, and bromotrichloromethane.

[0031] Preferably, in the activator emulsion of step S2, the mass ratio of the swelling agent, acetone and SDS aqueous solution is 1:1-2:10-20, and the mass concentration of the SDS aqueous solution is 0.25-1%;

[0032] In the monomer emulsion of step S2, the mass ratio of glycidyl methacrylate, divinylbenzene, porogen, and benzoyl peroxide is 1:0.5-1.5:1-2:0.03-0.06;

[0033] The mass concentration of the oil phase component in the monomer emulsion is 10-20%, wherein the oil phase component comprises glycidyl methacrylate, divinyl benzene, a porogen and benzoyl peroxide.

[0034] Preferably, in step S2-1, the mass ratio of the swelling agent to the styrene seed microspheres is 2 to 4:1;

[0035] In step S2-2, the ratio of the monomer emulsion to the seed suspension is such that the mass ratio of the oil phase component to the seed microspheres is 50 to 300:1.

[0036] Preferably, the swelling agent is a mixture of one or more of 1-chlorododecane, dibutyl phthalate, and bis(2-ethylhexyl) adipate;

[0037] The porogen is a mixture of one or more of toluene, n-heptane, and cyclohexanol;

[0038] The polyamine is a mixture of one or more of ethylenediamine, diethylenetriamine, triethylenetetramine, and polyethyleneimine in any proportion;

[0039] The organic solvent is a mixture of one or more of DMF, acetonitrile, diglyme, and tetrahydrofuran.

[0040] Preferably, in step S4, the mass ratio of succinic anhydride to PGMA-HPG is 1:0.5-2.

[0041] Preferably, the method for preparing the monodisperse magnetic microspheres modified with polycarboxyl hyperbranched polyglycerol comprises the following steps:

[0042] S1. Preparation of polystyrene seed microsphere suspension:

[0043] Dissolve borax in ultrapure water, then add refined styrene, stir for 15-60 minutes under nitrogen atmosphere and heat to 75-85°C, add ultrapure water containing potassium persulfate to the obtained mixture, add chain transfer agent dropwise after 2-10 minutes, stir at 100-400 rpm under nitrogen atmosphere and react at 75-85°C for 10-40 hours, remove residual styrene by water dialysis after the reaction is completed, and obtain a polystyrene seed microsphere suspension;

[0044] S2. Preparation of PGMA-NH2 microspheres:

[0045] S2-1. Preparation of activated seed suspension:

[0046] Acetone, a swelling agent and a 0.25-1% SDS aqueous solution are mixed, and homogenized at 200-600 bar using a Naton high-pressure homogenizer for 2-4 cycles to obtain an activator emulsion after homogenization; the polystyrene seed microspheres prepared in step S1 are added to the activator emulsion, and stirred at 20-40° C. for 12-48 hours to obtain an activated seed suspension;

[0047] S2-2. Preparation of porous PGMA microspheres:

[0048] Glycidyl methacrylate, divinylbenzene, porogen, and benzoyl peroxide are added to an SDS aqueous solution with a mass concentration of 0.1-0.5%, and mixed. The mixture is homogenized at 200-600 bar for 2-4 cycles using a Naton high-pressure homogenizer to obtain a monomer emulsion after homogenization. The monomer emulsion is added to the activated seed suspension prepared in step S2-1, and the mixture is swelled at 20-40° C. for 1-4 hours. The PVA aqueous solution is then added, and the mixture is stirred and reacted at 75-85° C. for 12-48 hours. After the reaction is completed, the mixture is centrifuged, and the solid product is extracted by Soxhlet extraction, and the extract is discarded. The solid product is retained, washed, and vacuum dried to obtain porous PGMA microspheres.

[0049] S2-3, Amination of porous PGMA microspheres:

[0050] The porous PGMA microspheres are dispersed in deionized water containing polyamines, reacted at 75-85°C for 24-96 hours, filtered after the reaction, and the solid product is washed and vacuum dried to obtain PGMA-NH2 microspheres;

[0051] S3. Preparation of magnetic PGMA microspheres:

[0052] The PGMA-NH2 microspheres prepared in step S2 are added to an aqueous solution containing FeSO4·7H2O and FeCl3·6H2O, stirred at room temperature for 15-60 min, heated to 75-85°C, added with aqueous ammonia, reacted for 0.5-2 h, cooled after the reaction, filtered, washed and vacuum dried the solid product to obtain magnetic PGMA microspheres: PGMA-M;

[0053] S4. Preparation of monodisperse magnetic microspheres modified with multi-carboxyl hyperbranched polyglycerol:

[0054] The PGMA-M prepared in step S3 is mixed with triethylamine and an organic solvent, stirred at 85-95° C. for 0.5-2 h, and then glycidol is added dropwise. After the addition is completed, the mixture is filtered, and the solid product is washed and vacuum dried to obtain PGMA-HPG microspheres;

[0055] PGMA-HPG microspheres are dispersed in an organic solvent with triethylamine and succinic anhydride, and reacted at 55-65° C. with stirring for 3-12 hours. After the reaction, the magnetic product is separated by magnetic attraction to obtain monodisperse magnetic microspheres modified with polycarboxyl hyperbranched polyglycerol: PGMA-HPG-COOH.

[0056] Preferably, the method for preparing the monodisperse magnetic microspheres modified with polycarboxyl hyperbranched polyglycerol comprises the following steps:

[0057] S1. Preparation of polystyrene seed microsphere suspension:

[0058] Dissolve 0.1-0.4 g of borax in 150-600 g of ultrapure water, then add 15-60 g of refined styrene, stir for 30 min under nitrogen atmosphere and heat to 80° C., add 5-20 mL of ultrapure water containing 0.15-0.6 g of potassium persulfate to the resulting mixture, add 1-4 g of chain transfer agent dropwise after 5 min, and complete the addition within 30 min, then react for 20 h under nitrogen atmosphere, stirring at 200 rpm, and at 80° C. After the reaction, remove the residual styrene by water dialysis to obtain a polystyrene seed microsphere suspension;

[0059] S2. Preparation of PGMA-NH2 microspheres:

[0060] S2-1. Preparation of activated seed suspension:

[0061] 0.4-1.6 g of acetone, 0.3-1.2 g of a swelling agent and 3-12 mL of a 0.25-1% SDS aqueous solution were mixed, and homogenized for 2 cycles at 400 bar using a Naton high-pressure homogenizer to obtain an activator emulsion after homogenization; 1-4 mL of the polystyrene seed microsphere suspension prepared in step S1 was added to the activator emulsion, and stirred at 30° C. for 24 h to obtain an activated seed suspension;

[0062] S2-2. Preparation of porous PGMA microspheres:

[0063] 3-12 g of glycidyl methacrylate, 2.5-10 g of divinylbenzene, 4.5-18 g of porogen, and 0.163-0.652 g of benzoyl peroxide are added to 60-240 mL of a 0.1-0.5% SDS aqueous solution, and the mixture is homogenized for 2 cycles at 400 bar using a Naton high-pressure homogenizer to obtain a monomer emulsion after homogenization; the monomer emulsion is added to the activated seed suspension prepared in step S2-1, and the mixture is swelled at 30° C. for 2 h, and then 60-240 mL of a 1.6-6.4 wt % PVA aqueous solution is added, and the mixture is stirred and reacted at 80° C. for 24 h. After the reaction is completed, the mixture is centrifuged, and the solid product is extracted by a Soxhlet extraction method, and the extract is discarded, and the solid product is retained, washed, and vacuum dried to obtain porous PGMA microspheres;

[0064] S2-3, Amination of porous PGMA microspheres:

[0065] 0.5-2 g of porous PGMA microspheres were dispersed in 10-40 mL of deionized water containing 2-8 g of polyamine, and the reaction was carried out at 80°C for 48 h. After the reaction was completed, the solid product was filtered, washed with methanol, and vacuum dried to obtain PGMA-NH2 microspheres;

[0066] S3. Preparation of magnetic PGMA microspheres:

[0067] 0.5-2 g of the PGMA-NH2 microspheres prepared in step S2 were added to a 10-40 mL aqueous solution containing 0.25-0.9 g of FeSO4·7H2O and 0.4-1.6 g of FeCl3·6H2O, stirred at room temperature for 30 min, heated to 80°C, added with 7.5-30 g of 20-25% ammonia water, reacted for 1 h, cooled after the reaction, filtered, and the solid product was washed with methanol and vacuum dried to obtain magnetic PGMA microspheres: PGMA-M;

[0068] S4. Preparation of monodisperse magnetic microspheres modified with multi-carboxyl hyperbranched polyglycerol:

[0069] 0.5-2 g of the PGMA-M prepared in step S3 was mixed with 250-1000 μL of triethylamine and 15-60 mL of an organic solvent, stirred at 90° C. for 1 h, and then 2.5-10 g of glycidol was added dropwise. After the addition was completed, the solid product was filtered, washed with methanol, and vacuum dried to obtain PGMA-HPG microspheres;

[0070] 0.25-1g PGMA-HPG microspheres, 0.25-1g triethylamine and 0.2-0.8g succinic anhydride were dispersed in 15-60mL organic solvent, stirred and reacted at 60°C for 6h. After the reaction, the magnetic product was separated by magnetic attraction to obtain monodisperse magnetic microspheres modified with polycarboxyl hyperbranched polyglycerol: PGMA-HPG-COOH.

[0071] The second aspect of the present invention provides an application of monodisperse magnetic microspheres modified with multi-carboxyl hyperbranched polyglycerol prepared by the method as described above, which is used for removing cationic dyes in wastewater.

[0072] The beneficial effects of the present invention are:

[0073] The invention provides a method for preparing monodisperse magnetic microspheres modified with polycarboxyl hyperbranched polyglycerol. The monodisperse magnetic microspheres have good stability, acid and alkali resistance, and a large specific surface area, are conducive to the attachment of dye molecules, can achieve efficient adsorption of cationic dyes, and can be applied to the removal of cationic dyes in wastewater.

[0074] In the present invention, the hyperbranched polyglycerol has abundant hydroxyl groups, which can be easily converted into various functional groups, and increase the water solubility of the material and the adsorption rate.

[0075] The monodisperse magnetic microspheres of the present invention have good magnetic properties and can be conveniently separated by applying a magnetic field. The separated materials can also be eluted with an eluent for recycling, thereby increasing economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0076] Figure 1 The Fourier transform infrared spectra of PGMA-HPG-COOH and its intermediates prepared in Example 1;

[0077] Figure 2 Thermogravimetric analysis of PGMA-HPG-COOH and its intermediates prepared in Example 1;

[0078] Figure 3 This is a scanning electron microscope photo of the PGMA-HPG-COOH prepared in Example 1;

[0079] Figure 4 hysteresis loop diagram of PGMA-M and PGMA-HPG-COOH prepared in Example 1;

[0080] Figure 5 The test results of the adsorption of four different dyes by the two microspheres of PGMA-HPG and PGMA-HPG-COOH prepared in Example 1 as adsorbents;

[0081] Figure 6 The test results of the adsorption of MB and R6G with an initial concentration of 200 mg / L by PGMA-HPG-COOH prepared in Example 1 over time;

[0082] Figure 7 This is a test curve diagram of the adsorption amount of PGMA-HPG-COOH prepared in Example 1 to MB and R6G of different concentrations. DETAILED DESCRIPTION

[0083] The present invention is further described in detail below in conjunction with embodiments so that those skilled in the art can implement the invention with reference to the description.

[0084] It should be understood that the terms such as “having”, “including” and “comprising” used herein do not exclude the existence or addition of one or more other elements or combinations thereof.

[0085] The test methods used in the following examples are conventional methods unless otherwise specified. The materials and reagents used in the following examples are all commercially available unless otherwise specified. In the following examples, if no specific conditions are specified, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used, if the manufacturer is not specified, are all conventional products that can be purchased commercially.

[0086] Example 1

[0087] S1. Preparation of polystyrene seed microsphere suspension:

[0088] Dissolve 0.19g of borax in 290g of ultrapure water, and then add 30g of refined styrene. Stir the mixture for 30min under a nitrogen atmosphere and heat to 80°C. Quickly add 10mL of ultrapure water containing 0.3g of potassium persulfate to the mixed solution, and the emulsion turns white after 5min. Then slowly add 2g of 2,4-diphenyl-4-methyl-1-pentene within 30min, and perform polymerization at 80°C at a speed of 200rpm under nitrogen for 20h. Remove the residual styrene by water dialysis to obtain a polystyrene seed microsphere suspension;

[0089] S2. Preparation of PGMA-NH2 microspheres:

[0090] S2-1. Preparation of activated seed suspension:

[0091] 0.8 g of acetone, 0.6 g of 1-chlorododecane and 6 mL of 0.5 wt% SDS aqueous solution were mixed, and homogenized for 2 cycles at 400 bar using a Naton high-pressure homogenizer to obtain an activator emulsion after homogenization. 2 mL of 10% (w / w) seed suspension was added to the activator emulsion, and the mixture was kept at 30° C. and stirred for 24 h to obtain an activated seed suspension.

[0092] S2-2. Preparation of porous PGMA microspheres:

[0093] 6 g of glycidyl methacrylate, 5 g of divinylbenzene, 5 g of toluene, 4 g of n-heptane and 0.326 g of benzoyl peroxide were added to 120 mL of 0.25 wt% SDS solution and mixed, and homogenized and emulsified for 2 cycles at 400 bar using a Naton high-pressure homogenizer to obtain a monomer emulsion after homogenization; the monomer emulsion was added to the activated seed suspension prepared in step S2-1, and after swelling at 30° C. for 2 h, 120 mL of 3.2 wt% PVA aqueous solution was added to the reactor, heated to 80° C. and stirred for 24 h, and centrifuged after the reaction was completed, and the solid product was extracted by Soxhlet extraction, the extract was discarded, and the solid product was retained, washed, and vacuum dried to obtain porous PGMA microspheres;

[0094] S2-3, Amination of porous PGMA microspheres:

[0095] 1 g of porous PGMA microspheres were dispersed in 20 mL of water containing 4 g of diethylenetriamine, reacted at 80 °C for 48 h, washed with methanol several times, and vacuum dried to obtain PGMA-NH2 microspheres;

[0096] S3. Preparation of magnetic PGMA microspheres:

[0097] Weigh 1 g of the PGMA-NH2 microspheres prepared in step S2, add them to 20 mL of an aqueous solution containing 0.45 g of FeSO4·7H2O and 0.8 g of FeCl3·6H2O, stir at room temperature for 30 min, and heat to 80°C; add 15 g of 25 wt% ammonia water, and continue the reaction for 1 h. After the reaction is completed, cool and filter, wash the solid product with methanol, and vacuum dry to obtain magnetic PGMA microspheres: PGMA-M;

[0098] S4. Preparation of monodisperse magnetic microspheres modified with multi-carboxyl hyperbranched polyglycerol:

[0099] 1 g of the PGMA-M prepared in step S3 was mixed with 500 μL of triethylamine and 30 mL of diethylene glycol dimethyl ether, and stirred at 90° C. for 1 h, and then 5 g of glycidol was added dropwise. After the addition was completed, the mixture was filtered, and the solid product was washed with methanol and dried in vacuo to obtain PGMA-HPG microspheres;

[0100] 0.5 g PGMA-HPG microspheres, 0.5 g triethylamine and 0.4 g succinic anhydride were dispersed in 30 mL diethylene glycol dimethyl ether, and the mixture was stirred at 60° C. for 6 h. After the reaction was completed, the magnetic product was separated by magnetic attraction to obtain monodisperse magnetic microspheres modified with polycarboxyl hyperbranched polyglycerol: PGMA-HPG-COOH.

[0101] Example 2

[0102] S1. Preparation of polystyrene seed microsphere suspension:

[0103] Dissolve 0.25g of borax in 290g of ultrapure water, and then add 20g of refined styrene. Stir the mixture for 30min under a nitrogen atmosphere and heat to 80°C. Quickly add 10mL of ultrapure water containing 0.2g of potassium persulfate to the mixed solution, and the emulsion turns white after 5min. Then slowly add 1.5g of 1-octanethiol within 30min, and perform polymerization at 80°C at a speed of 200rpm under nitrogen for 20h. Remove the residual styrene by water dialysis to obtain a polystyrene seed microsphere suspension;

[0104] S2. Preparation of PGMA-NH2 microspheres:

[0105] S2-1. Preparation of activated seed suspension:

[0106] 0.6 g of acetone, 0.6 g of bis(2-ethylhexyl) adipate and 6 mL of 0.5 wt% SDS aqueous solution were mixed, and homogenized for 2 cycles at 400 bar using a Naton high-pressure homogenizer to obtain an activator emulsion after homogenization. 2 mL of 10% (w / w) seed suspension was added to the activator emulsion, and the mixture was kept at 30° C. and stirred for 24 h to obtain an activated seed suspension.

[0107] S2-2. Preparation of porous PGMA microspheres:

[0108] 8 g of glycidyl methacrylate, 3 g of divinylbenzene, 5 g of toluene and 0.326 g of benzoyl peroxide were added to 120 mL of 0.25 wt% SDS solution and mixed, and homogenized and emulsified for 2 cycles at 400 bar using a Naton high-pressure homogenizer to obtain a monomer emulsion after homogenization; the monomer emulsion was added to the activated seed suspension prepared in step S2-1, and after swelling at 30° C. for 2 h, 120 mL of 3.2 wt% PVA aqueous solution was added to the reactor, and the suspension was heated to 80° C. and stirred for 24 h. After the reaction was completed, the suspension was centrifuged, and the solid product was extracted by Soxhlet extraction, the extract was discarded, and the solid product was retained, washed, and vacuum dried to obtain porous PGMA microspheres;

[0109] S2-3, Amination of porous PGMA microspheres:

[0110] 1 g of porous PGMA microspheres were dispersed in 20 mL of water containing 4 g of ethylenediamine, reacted at 80 °C for 48 h, washed with methanol several times, and vacuum dried to obtain PGMA-NH2 microspheres;

[0111] S3. Preparation of magnetic PGMA microspheres:

[0112] Weigh 1 g of the PGMA-NH2 microspheres prepared in step S2, add them to 20 mL of an aqueous solution containing 0.45 g of FeSO4·7H2O and 0.8 g of FeCl3·6H2O, stir at room temperature for 30 min, and heat the suspension to 80°C. Add 15 g of 25 wt% ammonia water, and continue the reaction for 1 h. After the reaction is completed, cool and filter, wash the solid product with methanol, and vacuum dry to obtain magnetic PGMA microspheres: PGMA-M;

[0113] S4. Preparation of monodisperse magnetic microspheres modified with multi-carboxyl hyperbranched polyglycerol:

[0114] 1 g of PGMA-M prepared in step S3 was mixed with 500 uL of triethylamine and 30 mL of acetonitrile, and stirred at 90°C for 1 h. Then 5 g of glycidol was added dropwise. After the addition was completed, the solid product was filtered, washed with methanol, and vacuum dried to obtain PGMA-HPG microspheres.

[0115] 0.5 g PGMA-HPG microspheres, 0.5 g triethylamine and 0.4 g succinic anhydride were dispersed in 30 mL acetonitrile, and the mixture was stirred at 60°C for 6 h. After the reaction, the magnetic product was separated by magnetic attraction to obtain monodisperse magnetic microspheres modified with polycarboxyl hyperbranched polyglycerol: PGMA-HPG-COOH.

[0116] Example 3

[0117] S1. Preparation of polystyrene seed microsphere suspension:

[0118] Dissolve 0.22g of borax in 290g of ultrapure water, and then add 30g of refined styrene. Stir the mixture for 30min under a nitrogen atmosphere and heat to 80°C. Quickly add 10mL of ultrapure water containing 0.2g of potassium persulfate to the mixed solution, and the emulsion turns white after 5min. Then slowly add 2g of 1-octanethiol within 30min, and perform polymerization at 80°C at a speed of 200rpm under nitrogen for 20h. Remove the residual styrene by water dialysis to obtain a polystyrene seed microsphere suspension;

[0119] S2. Preparation of PGMA-NH2 microspheres:

[0120] S2-1. Preparation of activated seed suspension:

[0121] 0.8 g of acetone, 0.6 g of dioctyl phthalate and 6 mL of 0.5% SDS aqueous solution were mixed, and homogenized for 2 cycles at 400 bar using a Naton high-pressure homogenizer to obtain an activator emulsion. 2 mL of 10% (w / w) seed suspension was added to the activator emulsion, and the mixture was kept at 30° C. and stirred for 24 h to obtain an activated seed suspension.

[0122] S2-2. Preparation of porous PGMA microspheres:

[0123] 3 g of glycidyl methacrylate, 3 g of divinylbenzene, 4 g of toluene and 0.18 g of benzoyl peroxide were added to 120 mL of 0.25 wt% SDS solution and mixed, and homogenized and emulsified for 2 cycles at 400 bar using a Naton high-pressure homogenizer to obtain a monomer emulsion after homogenization; the monomer emulsion was added to the activated seed suspension prepared in step S2-1, and after swelling at 30° C. for 2 h, 80 mL of 3.2 wt% PVA aqueous solution was added to the reactor, and the suspension was heated to 80° C. and stirred for 24 h. After the reaction was completed, the suspension was centrifuged, and the solid product was extracted by Soxhlet extraction, the extract was discarded, and the solid product was retained, washed, and vacuum dried to obtain porous PGMA microspheres;

[0124] S2-3, Amination of porous PGMA microspheres:

[0125] 1 g of porous PGMA microspheres were dispersed in 20 mL of water containing 4 g of polyethyleneimine (Mn = 600), reacted at 80 °C for 48 h, and washed with methanol several times to obtain PGMA-NH2 microspheres;

[0126] Weigh 1 g of the PGMA-NH2 microspheres prepared in step S2, add them to 20 mL of an aqueous solution containing 0.45 g of FeSO4·7H2O and 0.8 g of FeCl3·6H2O, stir at room temperature for 30 min, and heat the suspension to 80°C. Add 15 g of 25 wt% ammonia water, and continue the reaction for 1 h. After the reaction is completed, cool and filter, wash the solid product with methanol, and vacuum dry to obtain magnetic PGMA microspheres: PGMA-M;

[0127] S4. Preparation of monodisperse magnetic microspheres modified with multi-carboxyl hyperbranched polyglycerol:

[0128] 1 g of PGMA-M prepared in step S3 was mixed with 500 uL of triethylamine and 30 mL of diethylene glycol dimethyl ether, and stirred at 90° C. for 1 h, and then 5 g of glycidol was added dropwise. After the addition was completed, the solid product was filtered, washed with methanol, and vacuum dried to obtain PGMA-HPG microspheres;

[0129] 0.5 g PGMA-HPG microspheres, 0.5 g triethylamine and 0.6 g succinic anhydride were dispersed in 30 mL acetonitrile, and the mixture was stirred at 60° C. for 6 h. After the reaction was completed, the magnetic product was separated by magnetic attraction to obtain monodisperse magnetic microspheres modified with polycarboxyl hyperbranched polyglycerol: PGMA-HPG-COOH.

[0130] Performance Testing

[0131] Taking Example 1 as an example, the final product prepared therein, the monodisperse magnetic microspheres PGMA-HPG-COOH modified with polycarboxyl hyperbranched polyglycerol, and the intermediate products (PGMA-NH2 microspheres, magnetic PGMA microspheres: PGMA-M, PGMA-HPG microspheres) PGMA-HPG microspheres were subjected to relevant performance tests, as follows.

[0132] 1. Infrared analysis: refer to Figure 1 For the analysis results, 3428, 1728, 1450, 1117cm -1 The characteristic absorption peak at 1117cm -1 It belongs to the stretching vibration of CO bond. After Fe3O4 modification, 575cm -1 The absorption band at 1149 cm-1 is attributed to the stretching vibration of the Fe-O band, indicating that Fe3O4 nanoparticles are generated inside the porous spheres. In the FTIR spectrum of PGMA-HPG, due to the increase of secondary and tertiary alcohols, -1 The characteristic peak (stretching vibration of CO bond) at 1728cm-1 shifted to the high frequency region. After reacting with succinic anhydride, the absorption band intensity of PGMA-HPG-COOH at 1728cm-1 was significantly enhanced, indicating that the carboxyl group was successfully introduced.

[0133] 2. Thermogravimetric analysis: refer to Figure 2 The results of the analysis showed that the weight loss of PGMA-NH2 was 94.72wt% below 800℃. It was found that the primary decomposition range of PGMA-M was between 300-450℃, and the organic components were almost completely decomposed at 600℃. The mass fraction of Fe3O4 in PGMA-M was about 17.2wt%. After polyglycerol modification, the proportion of iron core in the microspheres decreased from 17.2% to 12%, and after carboxyl modification, the proportion of iron core further decreased to 9.9%.

[0134] 3. Reference Figure 3 , is a scanning electron microscope photo of PGMA-HPG-COOH. It can be seen that the microspheres have uniform particle size and are monodisperse, and there are magnetic particles and polymers attached to the surface, indicating that the polyglycerol modification is successful.

[0135] 4. Reference Figure 4 , which are the hysteresis loop diagrams of PGMA-M and PGMA-HPG-COOH, indicating that PGMA-HPG-COOH retains good magnetic properties; the turbid liquid in the lower right corner of the figure is a PGMA-HPG-COOH suspension, and the figure on the right side of the turbid liquid shows that the adsorbent is enriched by the magnet and the solution becomes clear.

[0136] 5. Test of the adsorption effect of PGMA-HPG-COOH and PGMA-HPG on dyes as adsorbents

[0137] Take 15 mg of the adsorbent (PGMA-HPG-COOH or PGMA-HPG) prepared in Example 1 and mix with 10 mL of dye (methylene blue, rhodamine 6G, rhodamine B, safranin T) solution with a concentration of 200 mg / L, respectively, and place the suspension in a constant temperature shaking shaker at a speed of 150 rpm and a temperature of 25°C. After adsorption, separate the adsorbent with a magnet, and determine the concentration of the supernatant by monitoring the change in absorbance at the characteristic absorption peak using ultraviolet-visible absorption spectroscopy. In the embodiment, the characteristic absorption peaks of MB and R6G are taken as 663 nm and 526 nm, respectively.

[0138] Reference Figure 5 , are the test results of the adsorption of four different dyes by two kinds of microspheres, PGMA-HPG and PGMA-HPG-COOH, as adsorbents; among them, (a) is the initial dye color; (b) is the color change diagram when PGMA-HPG is added as an adsorbent; (c) is the color change diagram when PGMA-HPG-COOH is added as an adsorbent; (d) is the test result diagram of the adsorption amount of different dyes by PGMA-HPG and PGMA-HPG-COOH.

[0139] According to the test results, after adding PGMA-HPG-COOH, the color of MB and R6G is obviously lighter than that of the original solution. Under the same conditions, the adsorption amount of PGMA-HPG is lower than that of PGMA-HPG-COOH ( Figure 5 b). When the initial dye concentration C0 was 200 mg / L, the equilibrium adsorption amounts of PGMA-HPG-COOH for MB and R6G were 119.2 mg / g and 102.7 mg / g, respectively, and the adsorption amounts of PGMA-HPG for MB and R6G were 0.5123 mg / g and 12.2 mg / g, respectively. In addition, the Qe (10.13 mg / g) of PGMA-HPG-COOH for RB was lower than that of the other three cationic dyes. The adsorption performance of PGMA-HPG-COOH strongly depends on electrostatic interactions. MB and R6G have positively charged groups and generate strong electrostatic attraction with the adsorbent. RB contains negative -COOH, so it has a weak electrostatic attraction with the surface of PGMA-HPG-COOH. Therefore, PGMA-HPG-COOH has high adsorption capacity and selective adsorption performance for MB and R6G.

[0140] Reference Figure 6 , which is the test result of the adsorption of MB and R6G by PGMA-HPG-COOH with an initial concentration of 200 mg / L over time; it can be seen that the rate of the adsorbent PGMA-HPG-COOH is very fast, and the adsorption equilibrium can be reached in 30 minutes at an initial dye concentration of 200 mg / g.

[0141] Figure 7 The test curve diagram of the adsorption amount of PGMA-HPG-COOH prepared in Example 1 to different concentrations of MB and R6G shows that the equilibrium adsorption amount of the dye increases with the increase of the initial dye concentration. When the initial dye concentration is 200 mg / L, the adsorption capacity of PGMA-HPG-COOH to methylene blue and rhodamine 6G is approximately 120 and 103 mg / g, respectively. The above results prove that the monodisperse magnetic microspheres modified with multi-carboxyl hyperbranched polyglycerol have excellent dye removal ability.

[0142] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to specific details.

Claims

1. A method for preparing monodisperse magnetic microspheres modified with polycarboxyl hyperbranched polyglycerol, characterized in that: The following steps are involved: S1, preparing a polystyrene seed microsphere suspension; S2. Preparation of PGMA-NH2 microspheres: S2-1. Preparation of activated seed suspension: Acetone, a swelling agent and an SDS aqueous solution are mixed and homogenized to obtain an activator emulsion; the polystyrene seed microsphere suspension prepared in step S1 is added to the activator emulsion and stirred to obtain an activated seed suspension; S2-2. Preparation of porous PGMA microspheres: Glycidyl methacrylate, divinylbenzene, a porogen, and benzoyl peroxide are added to an SDS aqueous solution and mixed, and then homogenized to obtain a monomer emulsion; the monomer emulsion is added to the activated seed suspension prepared in step S2-1 to swell, and then a PVA aqueous solution is added, and the mixture is heated and stirred for reaction, and after the reaction is completed, the mixture is centrifuged, and the solid product is extracted by a Soxhlet extraction method, and the extract is discarded, and the solid product is retained, washed, and vacuum dried to obtain porous PGMA microspheres; S2-3, Amination of porous PGMA microspheres: The porous PGMA microspheres are dispersed in deionized water containing polyamines, heated for reaction, filtered after the reaction is completed, and the solid product is washed and vacuum dried to obtain PGMA-NH2 microspheres; S3. Preparation of magnetic PGMA microspheres: Take the PGMA-NH2 microspheres prepared in step S2 and add them to the Fe 2+ and Fe 3+ The solution is heated after stirring, and aqueous ammonia is added to react. After the reaction is completed, the solution is cooled, filtered, and the solid product is washed and vacuum dried to obtain magnetic PGMA microspheres: PGMA-M. S4. Preparation of monodisperse magnetic microspheres modified with multi-carboxyl hyperbranched polyglycerol: The PGMA-M prepared in step S3 is mixed with triethylamine and an organic solvent, heated and stirred, and then glycidol is added dropwise. After the addition is completed, the solid product is filtered, washed, and vacuum dried to obtain PGMA-HPG microspheres; PGMA-HPG microspheres, triethylamine and succinic anhydride are dispersed in an organic solvent, heated and stirred for reaction, and after the reaction, the magnetic product is separated by magnetic attraction to obtain monodisperse magnetic microspheres modified with multi-carboxyl hyperbranched polyglycerol: PGMA-HPG-COOH.

2. The method for preparing monodisperse magnetic microspheres modified by polycarboxyl hyperbranched polyglycerol according to claim 1, characterized in that, Step S1 is specifically as follows: Borax is dissolved in ultrapure water, and then refined styrene is added, heated and stirred under a nitrogen atmosphere, potassium persulfate is added to the resulting mixture, and then a chain transfer agent is added dropwise, and heated and stirred to react under a nitrogen atmosphere. After the reaction is completed, residual styrene is removed by water dialysis to obtain a polystyrene seed microsphere suspension.

3. The method for preparing monodisperse magnetic microspheres modified by polycarboxyl hyperbranched polyglycerol according to claim 2, characterized in that, In step S1, the mass ratio of styrene, borax, potassium persulfate and chain transfer agent is 30:0.1-0.3:0.2-0.4:0.6-3, wherein the amount of ultrapure water added is such that the mass concentration of styrene in ultrapure water is 10-20%; The chain transfer agent is a mixture of one or more of 2,4-diphenyl-4-methyl-1-pentene, 1-octanethiol, and bromotrichloromethane.

4. The method for preparing monodisperse magnetic microspheres modified by polycarboxyl hyperbranched polyglycerol according to claim 1, characterized in that, In the activator emulsion of step S2, the mass ratio of the swelling agent, acetone and SDS aqueous solution is 1:1-2:10-20, and the mass concentration of the SDS aqueous solution is 0.25-1%; In the monomer emulsion of step S2, the mass ratio of glycidyl methacrylate, divinylbenzene, porogen, and benzoyl peroxide is 1:0.5-1.5:1-2:0.03-0.06; The mass concentration of the oil phase component in the monomer emulsion is 10-20%, wherein the oil phase component comprises glycidyl methacrylate, divinyl benzene, a porogen and benzoyl peroxide.

5. The method for preparing monodisperse magnetic microspheres modified by polycarboxyl hyperbranched polyglycerol according to claim 4, characterized in that, In step S2-1, the mass ratio of the swelling agent to the styrene seed microspheres is 2 to 4:1; In step S2-2, the ratio of the monomer emulsion to the seed suspension is such that the mass ratio of the oil phase component to the seed microspheres is 50 to 300:

1.

6. The method for preparing monodisperse magnetic microspheres modified by polycarboxyl hyperbranched polyglycerol according to claim 5, characterized in that, The swelling agent is a mixture of one or more of 1-chlorododecane, dibutyl phthalate, and bis(2-ethylhexyl) adipate; The porogen is a mixture of one or more of toluene, n-heptane, and cyclohexanol; The polyamine is a mixture of one or more of ethylenediamine, diethylenetriamine, triethylenetetramine, and polyethyleneimine in any proportion; The organic solvent is a mixture of one or more of DMF, acetonitrile, diglyme, and tetrahydrofuran.

7. The method for preparing monodisperse magnetic microspheres modified by polycarboxyl hyperbranched polyglycerol according to claim 1, characterized in that, In step S4, the mass ratio of succinic anhydride to PGMA-HPG is 1:0.5-2.

8. The method for preparing monodisperse magnetic microspheres modified by polycarboxyl hyperbranched polyglycerol according to claim 1, characterized in that, The following steps are involved: S1. Preparation of polystyrene seed microsphere suspension: Dissolve borax in ultrapure water, then add refined styrene, stir for 15-60 minutes under nitrogen atmosphere and heat to 75-85°C, add ultrapure water containing potassium persulfate to the obtained mixture, add chain transfer agent dropwise after 2-10 minutes, stir at 100-400 rpm under nitrogen atmosphere and react at 75-85°C for 10-40 hours, remove residual styrene by water dialysis after the reaction is completed, and obtain a polystyrene seed microsphere suspension; S2. Preparation of PGMA-NH2 microspheres: S2-1. Preparation of activated seed suspension: Acetone, a swelling agent and a 0.25-1% SDS aqueous solution are mixed, and homogenized at 200-600 bar using a Naton high-pressure homogenizer for 2-4 cycles to obtain an activator emulsion after homogenization; the polystyrene seed microsphere suspension prepared in step S1 is added to the activator emulsion, and stirred at 20-40° C. for 12-48 hours to obtain an activated seed suspension; S2-2. Preparation of porous PGMA microspheres: Glycidyl methacrylate, divinylbenzene, a porogen, and benzoyl peroxide are added to an SDS aqueous solution with a mass concentration of 0.1-0.5%, and mixed. The mixture is homogenized at 200-600 bar for 2-4 cycles using a Naton high-pressure homogenizer to obtain a monomer emulsion after homogenization. The monomer emulsion is added to the activated seed suspension prepared in step S2-1, and the mixture is swelled at 20-40° C. for 1-4 hours. The PVA aqueous solution is then added, and the mixture is stirred and reacted at 75-85° C. for 12-48 hours. After the reaction is completed, the mixture is centrifuged, and the solid product is extracted by Soxhlet extraction, and the extract is discarded. The solid product is retained, washed, and vacuum dried to obtain porous PGMA microspheres. S2-3, Amination of porous PGMA microspheres: The porous PGMA microspheres are dispersed in deionized water containing polyamines, reacted at 75-85°C for 24-96 hours, filtered after the reaction, and the solid product is washed and vacuum dried to obtain PGMA-NH2 microspheres; S3. Preparation of magnetic PGMA microspheres: The PGMA-NH2 microspheres prepared in step S2 are added to an aqueous solution containing FeSO4·7H2O and FeCl3·6H2O, stirred at room temperature for 15-60 min, heated to 75-85°C, added with aqueous ammonia, reacted for 0.5-2 h, cooled after the reaction, filtered, washed and vacuum dried the solid product to obtain magnetic PGMA microspheres: PGMA-M; S4. Preparation of monodisperse magnetic microspheres modified with multi-carboxyl hyperbranched polyglycerol: The PGMA-M prepared in step S3 is mixed with triethylamine and an organic solvent, stirred at 85-95° C. for 0.5-2 h, and then glycidol is added dropwise. After the addition is completed, the mixture is filtered, and the solid product is washed and vacuum dried to obtain PGMA-HPG microspheres; PGMA-HPG microspheres are dispersed in an organic solvent with triethylamine and succinic anhydride, and reacted at 55-65° C. with stirring for 3-12 hours. After the reaction, the magnetic product is separated by magnetic attraction to obtain monodisperse magnetic microspheres modified with polycarboxyl hyperbranched polyglycerol: PGMA-HPG-COOH.

9. The method for preparing monodisperse magnetic microspheres modified by polycarboxyl hyperbranched polyglycerol according to claim 8, characterized in that, The following steps are involved: S1. Preparation of polystyrene seed microsphere suspension: Dissolve 0.1-0.4 g of borax in 150-600 g of ultrapure water, then add 15-60 g of refined styrene, stir for 30 min under nitrogen atmosphere and heat to 80° C., add 5-20 mL of ultrapure water containing 0.15-0.6 g of potassium persulfate to the resulting mixture, add 1-4 g of chain transfer agent dropwise after 5 min, and complete the addition within 30 min, then react for 20 h under nitrogen atmosphere, stirring at 200 rpm, and at 80° C. After the reaction, remove the residual styrene by water dialysis to obtain a polystyrene seed microsphere suspension; S2. Preparation of PGMA-NH2 microspheres: S2-1. Preparation of activated seed suspension: 0.4-1.6 g of acetone, 0.3-1.2 g of a swelling agent and 3-12 mL of a 0.25-1% SDS aqueous solution were mixed, and homogenized for 2 cycles at 400 bar using a Naton high-pressure homogenizer to obtain an activator emulsion after homogenization; 1-4 mL of the polystyrene seed microsphere suspension prepared in step S1 was added to the activator emulsion, and stirred at 30° C. for 24 h to obtain an activated seed suspension; S2-2. Preparation of porous PGMA microspheres: 3-12 g of glycidyl methacrylate, 2.5-10 g of divinylbenzene, 4.5-18 g of porogen, and 0.163-0.652 g of benzoyl peroxide are added to 60-240 mL of a 0.1-0.5% SDS aqueous solution, and the mixture is homogenized for 2 cycles at 400 bar using a Naton high-pressure homogenizer to obtain a monomer emulsion after homogenization; the monomer emulsion is added to the activated seed suspension prepared in step S2-1, and the mixture is swelled at 30° C. for 2 h, and then 60-240 mL of a 1.6-6.4 wt % PVA aqueous solution is added, and the mixture is stirred and reacted at 80° C. for 24 h. After the reaction is completed, the mixture is centrifuged, and the solid product is extracted by a Soxhlet extraction method, and the extract is discarded, and the solid product is retained, washed, and vacuum dried to obtain porous PGMA microspheres; S2-3, Amination of porous PGMA microspheres: 0.5-2 g of porous PGMA microspheres were dispersed in 10-40 mL of deionized water containing 2-8 g of polyamine, and the reaction was carried out at 80°C for 48 h. After the reaction was completed, the solid product was filtered, washed with methanol, and vacuum dried to obtain PGMA-NH2 microspheres; S3. Preparation of magnetic PGMA microspheres: 0.5-2 g of the PGMA-NH2 microspheres prepared in step S2 were added to a 10-40 mL aqueous solution containing 0.25-0.9 g of FeSO4·7H2O and 0.4-1.6 g of FeCl3·6H2O, stirred at room temperature for 30 min, heated to 80°C, added with 7.5-30 g of 20-25% ammonia water, reacted for 1 h, cooled after the reaction, filtered, and the solid product was washed with methanol and vacuum dried to obtain magnetic PGMA microspheres: PGMA-M; S4. Preparation of monodisperse magnetic microspheres modified with multi-carboxyl hyperbranched polyglycerol: 0.5-2 g of the PGMA-M prepared in step S3 was mixed with 250-1000 μL of triethylamine and 15-60 mL of an organic solvent, stirred at 90° C. for 1 h, and then 2.5-10 g of glycidol was added dropwise. After the addition was completed, the solid product was filtered, washed with methanol, and vacuum dried to obtain PGMA-HPG microspheres; 0.25-1g PGMA-HPG microspheres, 0.25-1g triethylamine and 0.2-0.8g succinic anhydride were dispersed in 15-60mL organic solvent, stirred and reacted at 60°C for 6h. After the reaction, the magnetic product was separated by magnetic attraction to obtain monodisperse magnetic microspheres modified with polycarboxyl hyperbranched polyglycerol: PGMA-HPG-COOH.

10. Use of monodisperse magnetic microspheres modified with multi-carboxyl hyperbranched polyglycerol prepared by any of the methods described above in claims 1 to 9, characterized in that: It is used to remove cationic dyes from wastewater.

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