A magnetic solid-phase extraction material, a preparation method and application thereof

Abstract

The application belongs to the technical field of inorganic materials and analysis, and relates to a magnetic solid-phase extraction material and a preparation method and application thereof. The preparation process of the extraction adsorbent is as follows: firstly, Fe3O4 nanoparticles are prepared by a solvothermal method; then the Fe3O4 nanoparticles are dispersed into 3D flower-shaped double hydroxides; finally, rod-shaped metal organic framework materials are embedded to obtain a magnetic composite material. The prepared magnetic extraction material is used as an adsorbent to carry out enrichment determination of organic phosphorus flame retardants in water samples. Based on the large specific surface area, good dispersity and various interactions such as affinity coordination, pi-pi and electrostatic attraction provided by the material, the material shows good extraction efficiency and selective recognition ability for target substances, and in combination with a high performance liquid chromatography-ultraviolet visible spectrometer, the material can be used for trace detection of organic phosphorus flame retardants in environmental water samples.

Description

Technical Field

[0001] This invention belongs to the field of inorganic materials and analytical technology, and relates to a magnetic solid phase extraction material, its preparation method and application. Background Technology

[0002] Organophosphorus flame retardants (OPFRs) are added to materials to enhance their fire resistance and are widely used in building materials, furniture, electronics, and textiles. However, the increasing use of OPFRs has also raised concerns about their adverse effects. OPFRs are not chemically bonded to materials and are easily released into the environment through abrasion, leaching, dissolution, or volatilization. OPFRs have been reported to be detected in indoor air, dust, drinking water, and soil. Toxicological studies have shown that OPFRs pose various potential hazards, including endocrine disruption, reproductive impairment, and neurotoxicity. Therefore, monitoring OPFRs in the environment is crucial. However, environmental matrices are often complex, and low OPFR concentrations can affect instrument detection. Therefore, sample pretreatment is necessary to separate OPFRs from complex matrices and concentrate them before analysis.

[0003] Magnetic solid-phase extraction (MSPE), as a novel solid-phase extraction technique, has attracted great interest from researchers due to its ease of operation and high efficiency. Compared with traditional solid-phase extraction, MSPE avoids the cumbersome and time-consuming problems of centrifugation and column clogging, and requires only a small amount of organic solvent to desorb the target analyte from the adsorbent. The magnetic adsorbent is the core of MSPE and a decisive factor affecting the extraction efficiency. Therefore, developing a magnetic adsorbent with high extraction efficiency and good selectivity is crucial. Magnetic materials typically utilize Fe3O4 to provide magnetism, and are further modified with other types of materials to improve selectivity and enrichment efficiency.

[0004] Layered hydrogen hydroxides (LDHs) are typical anionic layered inorganic materials with advantages such as high stability, flexible composition, and strong ion exchange capacity. These properties make LDHs promising candidates for the adsorption and removal of analytes, particularly inorganic anions such as chromates, phosphates, and arsenites / arsenates. Furthermore, improving the adsorption capacity of LDHs for organic pollutants is also crucial. Efficiency can be significantly improved by inserting organic matter into the intermediate layer of LDHs or by combining LDHs with other suitable materials. Metal-organic frameworks (MOFs) have attracted widespread attention in the field of pollutant pretreatment due to their good stability, large specific surface area, and high porosity. For example, titanium-based MOFs possess advantages such as low toxicity, good biocompatibility, versatility, relatively low cost, and ease of synthesis, making them ideal water treatment adsorbents. Existing studies have shown that MIL-125(Ti)-based adsorbents have good removal effects on tetracyclines, dyes, and pesticides in the environment.

[0005] Therefore, there is a need to develop a material based on layered double hydroxides and metal-organic frameworks to enrich and separate low-concentration OPFRs in the environment, so that they can be concentrated and analyzed. Summary of the Invention

[0006] Based on the above, the present invention aims to prepare magnetic nanocomposite materials for the magnetic solid-phase extraction and enrichment of organophosphorus flame retardants in environmental water samples. Specifically, a well-dispersible, small-particle-size Fe3O4 material is prepared, and then the Fe3O4 material is modified into a 3D flower-like double hydroxide to obtain a layered double hydroxide magnetic material. Finally, a rod-shaped metal-organic framework material is embedded into the layers of the 3D flower-like double hydroxide through a hydrothermal synthesis reaction to obtain a metal-organic framework-modified magnetic double hydroxide nanocomposite material.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] In a first aspect, the present invention provides a magnetic solid-phase extraction material, which is based on a layered double hydroxide and a metal-organic framework material. The core is a plurality of Fe3O4 nanoparticles, and the surface of the plurality of Fe3O4 nanoparticles is grown and wrapped with a flower-like layered structure of 3D double hydroxide to form microspheres. A rod-shaped metal-organic framework material is loaded and inserted into the layered structure of the double hydroxide. The size of the Fe3O4 nanoparticles is 20-100 nm, the microspheres formed by the double hydroxide flower-like nanosheets wrapping the Fe3O4 nanoparticles are 1-6 μm in size, and the size of the rod-shaped metal-organic framework embedded between the flower-like nanosheets is smaller than that of the flower-like microsphere structure.

[0009] In a second aspect, the present invention provides a method for preparing the magnetic solid-phase extraction adsorbent described in the first aspect, specifically comprising the following steps:

[0010] S1 Preparation of Fe3O4 nanoparticles: Preparation of Fe3O4 nanoparticles by solvothermal method;

[0011] S2 preparation of 3D flower-like double hydroxide materials encapsulating Fe3O4:

[0012] The Fe3O4 prepared in step S1 was dispersed in deionized water and sonicated. Then, nickel nitrate hexahydrate, aluminum nitrate nonahydrate, urea and ammonium fluoride were added in a molar ratio of (1-2):(0.3-1):(8-11):(3-5). After stirring evenly, the above mixed solution was transferred to a stainless steel autoclave lined with polytetrafluoroethylene and kept at 100-150°C for 10-24 hours. After cooling, it was washed with water and ethanol to obtain a 3D flower-shaped double hydroxide material encapsulating Fe3O4.

[0013] S3 Preparation of Magnetic Extraction Materials for 3D Flower-like Double Hydroxide-Supported Rod-like Metal-Organic Framework Materials:

[0014] The 3D flower-like double hydroxide material encapsulating Fe3O4 obtained in step S2 was placed in a mixed solvent of N,N-dimethylformamide and methanol. Then, terephthalic acid and tetraisopropyl titanate were added to the suspension. After stirring and sonication, the reaction mixture was transferred to a stainless steel autoclave lined with polytetrafluoroethylene and reacted at 100–180 °C for 15–25 h. After cooling, it was washed with N,N-dimethylformamide and methanol to remove unreacted organic ligands. The resulting magnetic extraction material was dried in a vacuum drying oven.

[0015] The mass ratio of the 3D flower-like double hydroxide material encapsulating Fe3O4, terephthalic acid, and tetraisopropyl titanate is 1:(2-3):(1.5-2.5).

[0016] Preferably, in step S3, the volume ratio of the two substances in the N,N-dimethylformamide and methanol mixed solvent is 7:1 to 10:1; the concentration of the 3D flower-like double hydroxide material encapsulating Fe3O4 in the N,N-dimethylformamide and methanol mixed solvent is 4 to 10 g / L.

[0017] Preferably, the solvothermal method in step S1 is operated as follows: ethylene glycol and water are mixed in a volume ratio of 4:1 to form a mixed solvent of ethylene glycol and aqueous solution; then, ferric chloride and anhydrous sodium acetate are added to the mixed solvent to make Fe... 3+ / Ac - The molar ratio was 1 / 3 to 1 / 7. After sonication for 10 to 40 minutes, the solution was transferred to a stainless steel autoclave lined with polytetrafluoroethylene and reacted at 150 to 400°C for 6 to 15 hours. After cooling, the mixture was centrifuged and washed continuously with water and ethanol to obtain Fe3O4 nanoparticles.

[0018] Thirdly, the present invention provides an application of the magnetic solid-phase extraction material described in the first aspect for the extraction and enrichment of organophosphorus flame retardants.

[0019] Preferably, the extraction and enrichment of the organophosphorus flame retardant includes the following steps:

[0020] The magnetic solid phase extraction material is added to the water sample to be tested, and the concentration of the magnetic solid phase extraction material is 0.1-0.9 g / L. The pH is adjusted to 6-9. Under the action of ultrasound, the magnetic solid phase extraction material is fully adsorbed by the pollutants in the water. Then, under the action of an external magnetic field, the magnetic solid phase extraction material is separated from the water sample, and the supernatant is discarded.

[0021] Furthermore, the pH value can be adjusted using HCl or NaOH.

[0022] Furthermore, the amount of magnetic solid-phase extraction material added is 15 mg / L, the pH of the water sample is adjusted to 9 with 0.1 M HCl or NaOH, and the extraction time is 11 min.

[0023] Preferably, the detection process after enrichment is as follows: acetonitrile eluent is added to the adsorbed magnetic solid-phase extraction material, and the resulting desorption solution is filtered through a filter membrane and then subjected to high-performance liquid chromatography-ultraviolet detection analysis.

[0024] Furthermore, the liquid chromatography analysis was performed using Sun Microsystems. C18 column (4.6 mm × 150 mm, 5 μm); mobile phase A was water containing 0.1% formic acid, mobile phase B was methanol with 0.1% formic acid added, A / B phase volume ratio was 1:9 isocratic elution, column temperature was 35 °C; flow rate was 1.0 mL / min; injection volume was 10 μL, detection wavelength was 210 nm.

[0025] Preferably, the organophosphorus flame retardant includes triphenyl phosphate, tricresyl phosphate, 2-ethylhexyl diphenyl phosphate, resorcinol tetraphenyl diphosphate, and bisphenol A bis(diphenyl phosphate).

[0026] The beneficial effects of this invention are as follows: By embedding Fe3O4 nanoparticles into a double hydroxide sheet, a magnetic material with a large specific surface area can be obtained. Modifying the rod-shaped metal-organic framework material further enhances the interaction between the extraction material and the analyte, and provides selective recognition capability. The magnetic extraction adsorbent prepared by this invention exhibits good selectivity and high extraction efficiency. Combined with a high-performance liquid chromatography-ultraviolet-visible spectroscopy detector, it can be used for trace detection of organophosphorus flame retardants in environmental water samples. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the preparation of the magnetic adsorbent Fe3O4 / NiAl LDH / MIL-125(Ti) and its magnetic solid-phase extraction process.

[0028] Figure 2 The images show scanning electron microscope (SEM) images of the materials at different stages of the preparation process. (a) is an SEM image of Fe3O4 nanoparticles, (b) is an SEM image of Fe3O4 / NiAl LDH particles coated with bimetallic hydroxide, and (c, d) are SEM images of the magnetic adsorbent Fe3O4 / NiAl LDH / MIL-125(Ti) loaded with MIL-125(Ti).

[0029] Figure 3 X-ray diffraction pattern (a), infrared spectrum (b), N2 adsorption-desorption isotherm (c), and X-ray photoelectron spectrum (d) of magnetic material Fe3O4 / NiAl LDH / MIL-125(Ti).

[0030] Figure 4 For the optimization of magnetic solid-phase extraction conditions: (a) Effect of adsorbent dosage on extraction peak area, (b) Effect of ultrasonic time on extraction peak area, (c) Effect of salt concentration on extraction peak area, (d) Effect of sample solution pH on extraction peak area, (e) Effect of elution solvent type on extraction peak area, and (f) Effect of elution volume on extraction peak area.

[0031] Figure 5 The image shows the HPLC-UV images of water samples from Zhanghu Lake and their spiked samples after magnetic solid-phase extraction.

[0032] Figure 6 The results of the selective experiments are shown in the figure. (a) is the HPLC-UV spectrum of organophosphorus flame retardants OPFRs before and after extraction and the standard sample. (b) and (c) are the HPLC-UV spectra of cyclic aromatic hydrocarbons (PAHs) and bisphenol compounds (BPs) before and after extraction and the standard sample, respectively. Detailed Implementation

[0033] The present invention will be further described and illustrated below with reference to the accompanying drawings and specific embodiments.

[0034] Example 1

[0035] The preparation of the magnetic solid-phase extraction material Fe3O4 / NiAl LDH / MIL-125(Ti) based on layered double hydroxides and metal-organic frameworks is as follows:

[0036] First, Fe3O4 nanoparticles were prepared via a solvothermal method. 40 mL of ethylene glycol was mixed with 10 mL of deionized water. 0.406 g of ferric chloride and 1.026 g of anhydrous sodium acetate were added to the mixed solvent. After sonication for 30 min, the solution was transferred to a stainless steel autoclave lined with polytetrafluoroethylene and reacted at 200 °C for 10 h. After cooling, the mixture was centrifuged, and the black precipitate was washed three times consecutively with water and ethanol to obtain the Fe3O4 nanoparticles.

[0037] Next, Fe3O4 nanoparticles were modified onto Ni / Ai double hydroxide nanospheres to prepare Fe3O4 / NiAl LDH composite material. The prepared Fe3O4 was dispersed in 70 mL of deionized water and sonicated for 1 h. Then, 0.436 g of nickel nitrate hexahydrate, 0.188 g of aluminum nitrate nonahydrate, 0.601 g of urea, and 0.148 g of ammonium fluoride were added to the solution. The mixture was transferred to a stainless steel autoclave lined with polytetrafluoroethylene and maintained at 120 °C for 18 h. After cooling, the mixture was centrifuged and washed three times with water and ethanol to obtain Fe3O4 / NiAl LDH.

[0038] Finally, a magnetic nanocomposite material, Fe3O4 / NiAl LDH / MIL-125(Ti), modified with the metal-organic framework material MIL-125(Ti), was prepared. The Fe3O4 / NiAl LDH material was dispersed in a mixed solvent of 22.5 mL N,N-dimethylformamide and 2.5 mL methanol. 0.415 g terephthalic acid and 0.296 mL tetraisopropyl titanate were added to the suspension. After stirring for 30 min and sonicating for 10 min, the reaction mixture was transferred to a stainless steel autoclave lined with polytetrafluoroethylene and maintained at 150 °C for 24 h. After cooling, the magnetic composite material Fe3O4 / NiAl LDH / MIL-125(Ti) was collected and washed several times with N,N-dimethylformamide and methanol to remove unreacted organic ligands. Finally, the product was dried in a vacuum drying oven at 60 °C to obtain the magnetic solid-phase extraction material Fe3O4 / NiAl LDH / MIL-125(Ti).

[0039] Example 2

[0040] The characterization and results of the magnetic solid-phase extraction material Fe3O4 / NiAl LDH / MIL-125(Ti) obtained in Example 1 are as follows:

[0041] The morphologies of Fe3O4, Fe3O4 / NiAl LDH, and Fe3O4 / NiAl LDH / MIL-125(Ti) were characterized using scanning electron microscopy. The results are as follows: Figure 2 As shown, Fe3O4 prepared by the hydrothermal method exhibits uniform and well-dispersed spherical shapes with a particle size of approximately 30-40 nm. In the Fe3O4 / NiAl-LDH composite material, a large number of Fe3O4 nanoparticles can be observed on the exposed NiAl-LDH flower-like nanosheets. NiAl-LDH is self-assembled from nanosheets, exhibiting a flower-like microsphere structure with a diameter of 3-5 μm. This structure allows for a larger exposed specific surface area, facilitating the growth of other adsorbents to form the composite material. SEM images of Fe3O4 / NiAl LDH / MIL-125(Ti) clearly show rod-shaped MIL-125(Ti) embedded within the Fe3O4 / NiAl LDH.

[0042] The X-ray diffraction spectrum of the composite material Fe3O4 / NiAl LDH / MIL-125(Ti) is as follows: Figure 3As shown in Figure a, in the XRD pattern of Fe3O4 / NiAl LDH / MIL-125(Ti), the distribution range of MIL-125(Ti) is 2θ = 6-23°. Characteristic peaks of Fe3O4 and NiAl LDH were also observed, such as the characteristic diffraction peaks at 2θ = 30.22°, 35.62°, 43.32°, 53.6°, 57.16°, and 62.84°, corresponding to the (220), (311), (400), (422), (511), and (440) crystal planes of Fe3O4. Furthermore, the (003), (006), and (009) diffraction peaks appearing at 2θ = 11.60°, 23.32°, and 35.04° exhibit characteristic reflections of LDH-type materials. The symmetrical and sharp diffraction peaks indicate a high degree of crystallinity in NiAl-LDH. These results indicate the successful synthesis of the Fe3O4 / NiAl LDH / MIL-125(Ti) composite material.

[0043] The Fourier transform infrared spectrum of the material Fe3O4 / NiAl LDH / MIL-125(Ti) is as follows: Figure 3 As shown in b, 549cm -1 The strong absorption peak at 3479 cm⁻¹ belongs to the tensile vibration of Fe-O, which proves the presence of Fe₃O₄ in the composite material. In the Fe₃O₄ / spectrum, the peak value is at 3479 cm⁻¹. -1 and 1358cm -1 The absorption peaks on the left and right correspond to interlayer water molecules in NiAl LDH and NO3, respectively. - OH tensile vibration caused by tensile vibration, 753cm -1 The absorption peak at 1599 cm⁻¹ is likely caused by the stretching and bending vibrations of the metal-oxygen bond (MO) in LDH. Additionally, the absorption peak at 1599 cm⁻¹... -1 The characteristic absorption peak of the benzene structure in MIL-125(Ti) appeared at 819 cm⁻¹. -1 The new absorption peak at 1018 cm⁻¹ is related to Ti-O stretching. -1 The new absorption peak at this location is related to the tensile vibration of Ti-OC.

[0044] The specific surface area, pore size, and pore volume of the Fe3O4 / NiAl LDH / MIL-125(Ti) composite material were characterized using a specific surface area analyzer. Figure 3 As shown in c, the BET specific surface area of ​​Fe3O4 / NiAl LDH / MIL-125(Ti) reaches 133.492 m². 2 ·g -1 The average pore size and pore volume of BJH are 8.1 nm and 0.204 cm, respectively. 3 ·g -1This indicates that the Fe3O4 / NiAlLDH / MIL-125(Ti) composite material has high porosity and high specific surface area, which can provide sufficient adsorption sites and help improve the extraction efficiency of OPFRs.

[0045] The elemental composition of the Fe3O4 / NiAl LDH / MIL-125(Ti) composite material was characterized by X-ray photoelectron spectroscopy, such as... Figure 3 XPS analysis, shown in figure d, further confirmed the presence of Fe, O, Ni, Al, C, and Ti elements on the surface of the prepared Fe3O4 / NiAl LDH / MIL-125(Ti) composite material. The four peaks observed at 711.95, 531.60, 284.80, and 68.60 eV belong to Fe 2p, O 1s, C 1s, and Al 2p, respectively. For Ni 2p, Ni... 2+ The binding energies of Ni 2p1 / 2 and Ni 2p3 / 2 in the orbitals are 874.12 eV and 856.42 eV, respectively, with corresponding satellite peaks at 879.97 and 862.05 eV. Furthermore, Ti 2p exhibits two strong peaks at 458.85 eV and 464.70 eV, belonging to Ti... 4+ Ti 2p3 / 2 and Ti 2p1 / 2 coordinated with oxygen.

[0046] Example 3

[0047] Optimization of magnetic solid phase extraction conditions:

[0048] A method for magnetic solid-phase extraction of organophosphorus flame retardants was established using the prepared Fe3O4 / NiAl LDH / MIL-125(Ti) as the extraction material. The steps are as follows: Figure 1 As shown.

[0049] To achieve higher extraction efficiency, this embodiment optimized several key experimental parameters, including the amount of adsorbent, extraction time, pH and ionic strength of the sample solution, and the type and volume of the desorption solvent. Figure 4 The effects of different extraction conditions on the peak area of ​​five organophosphorus flame retardants were presented. The five analytes were triphenyl phosphate (TPP), tricresyl phosphate (TCP), 2-ethylhexyl diphenyl phosphate (EDP), resorcinol tetraphenyl diphosphate (RBDP), and bisphenol A bis(diphenyl phosphate) (BADP).

[0050] The optimal conditions are as follows: 15 mg / 35 mL Fe3O4 / NiAl LDH / MIL-125(Ti) is the appropriate dosage for subsequent experiments; 11 min is selected as the extraction time; NaCl is not required to be added to the sample solution; the pH of the sample solution is adjusted to 9; pure acetonitrile is selected as the elution solvent; and a volume of 400 μL is sufficient to achieve effective desorption.

[0051] Example 4

[0052] Methodological representation:

[0053] Under the extraction conditions determined in Example 3 above, the established magnetic solid-phase extraction-HPLC-UV method was characterized methodologically, and the results are shown in Table 1. Five organophosphorus flame retardants were tested at concentrations ranging from 1-400 ng / mL. -1 It exhibits a good linear relationship within the concentration range, R 2 The range was 0.9976-0.9996, with limits of detection and quantitation of 0.3-1.0 ng / mL, respectively. -1 and 1.0-3.0 ng·mL -1 The intraday and interday relative standard deviations are less than 9.94% (n=3).

[0054] Table 1 Analytical performance of the MSPE-HPLC-UV analytical method

[0055]

[0056] Example 5

[0057] Actual sample application results:

[0058] This method was applied to the determination of organophosphorus flame retardants in three local environmental water samples (Daliao River-1, Hanzhang Lake-2, and campus water-3). The results are shown in Table 2. No target compounds were detected in any of the three water samples. (The last part, "10 ng·mL," appears to be an unrelated fragment and is omitted from the translation.) -1 and 100 ng·mL -1 The accuracy of the method was evaluated at two different spiking concentrations, with recoveries ranging from 82.79% to 111.32% and relative standard deviations from 0.53% to 10.28%. The chromatograms of water sample-1 and its spiked sample after magnetic solid-phase extraction are shown below. Figure 5 As shown.

[0059] Table 2. Determination and recovery rates of five OPFRs in water samples (n=3)

[0060]

[0061] Example 6

[0062] Selective evaluation:

[0063] To evaluate the adsorption selectivity of the Fe3O4 / NiAl LDH / MIL-125(Ti) composite material for organophosphorus flame retardants (OPFRs), this example compares the extraction analysis of polycyclic aromatic hydrocarbons (PAHs) and bisphenol compounds (BPs) under the same conditions. Figure 6 The HPLC-UV chromatograms of the sample solutions of the three types of compounds before and after extraction, as well as their standards, are presented. It can be seen that the Fe3O4 / NiAl LDH / MIL-125(Ti) composite material exhibits good selectivity for the five organophosphorus flame retardants.

[0064] This invention prepares a novel magnetic double hydroxide supported on a metal-organic framework material and, for the first time, applies it as a magnetic solid-phase extraction adsorbent for the enrichment of organophosphorus flame retardants in environmental water samples. Compared with other sample pretreatment methods, the method of this invention is simpler and faster, requires less adsorbent, and has a shorter extraction time.

[0065] The above-described embodiments are merely illustrative of the implementation methods of the present invention, but should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the protection scope of the present invention.

Claims

1. A magnetic solid phase extraction material for the extraction enrichment of organophosphorus flame retardants, characterized in that, The magnetic solid phase extraction material is based on layered double hydroxide and metal organic framework material, the inner core is a plurality of Fe3O4 nanoparticles, the surface of the plurality of Fe3O4 nanoparticles grows to wrap a flower-shaped sheet structure 3D double hydroxide to form a microsphere, and a rod-shaped metal organic framework material is loaded and inserted into the sheet structure of the double hydroxide; wherein the size of the Fe3O4 nanoparticles is 20-100 nm, the microsphere formed by the flower-shaped nanosheet layer of the double hydroxide wrapping the Fe3O4 nanoparticles is 1-6 μm, and the size of the rod-shaped metal organic framework embedded between the flower-shaped nanosheets is less than that of the flower-shaped microsphere structure. The preparation of the material specifically includes the following steps: S1: preparing Fe3O4 nanoparticles: preparing Fe3O4 nanoparticles by a solvothermal method; S2: preparing 3D flower-shaped double hydroxide material wrapping Fe3O4: The Fe3O4 nanoparticles prepared in step S1 are dispersed in deionized water and ultrasonicated, then nickel nitrate hexahydrate, aluminum nitrate nonahydrate, urea and ammonium fluoride are added, the molar ratio of the four substances is (1-2):(0.3-1):(8-11):(3-5); after stirring uniformly, the above mixed solution is transferred to a stainless steel autoclave with a polytetrafluoroethylene liner, kept at 100-150 DEG C for 10-24 h, washed with water and ethanol after cooling, and the 3D flower-shaped double hydroxide material wrapping Fe3O4 is obtained; S3: preparing a magnetic extraction material of 3D flower-shaped double hydroxide loaded with a rod-shaped metal organic framework material: The 3D flower-shaped double hydroxide material wrapping Fe3O4 prepared in step S2 is dispersed in a mixed solvent of N,N-dimethylformamide and methanol, then terephthalic acid and titanium isopropylate are added to the above suspension, after stirring and ultrasonication, the reaction mixture is transferred to a stainless steel autoclave with a polytetrafluoroethylene liner, and reacted at 100-180 DEG C for 15-25 h; after cooling, it is washed with N,N-dimethylformamide and methanol to remove unreacted organic ligands, and the obtained magnetic extraction material is vacuum dried; The mass ratio of the 3D flower-shaped double hydroxide material wrapping Fe3O4, terephthalic acid and titanium isopropylate is 1:(2-3):(1.5-2.5).

2. A method for preparing the magnetic solid-phase extraction adsorbent material for extraction enrichment of organophosphorus flame retardants according to claim 1, characterized in that, Specifically includes the following steps: S1: preparing Fe3O4 nanoparticles: preparing Fe3O4 nanoparticles by a solvothermal method; S2: preparing 3D flower-shaped double hydroxide material wrapping Fe3O4: The Fe3O4 nanoparticles prepared in step S1 are dispersed in deionized water and ultrasonicated, then nickel nitrate hexahydrate, aluminum nitrate nonahydrate, urea and ammonium fluoride are added, the molar ratio of the four substances is (1-2):(0.3-1):(8-11):(3-5); after stirring uniformly, the above mixed solution is transferred to a stainless steel autoclave with a polytetrafluoroethylene liner, kept at 100-150 DEG C for 10-24 h, washed with water and ethanol after cooling, and the 3D flower-shaped double hydroxide material wrapping Fe3O4 is obtained; S3: preparing a magnetic extraction material of 3D flower-shaped double hydroxide loaded with a rod-shaped metal organic framework material: The Fe3O4-coated 3D flower-like double hydroxide material prepared in step S2 is dispersed in a mixed solvent of N,N-dimethylformamide and methanol, terephthalic acid and titanium acid tetraisopropyl are then added to the suspension, after stirring and ultrasonic treatment, the reaction mixture is transferred to a polytetrafluoroethylene-lined stainless steel autoclave, and reacted at 100-180℃ for 15-25 h; after cooling, it is washed with N,N-dimethylformamide and methanol to remove unreacted organic ligands, and the obtained magnetic extraction material is vacuum dried; The mass ratio of the Fe3O4-coated 3D flower-like double hydroxide material, terephthalic acid and titanium acid tetraisopropyl is 1:(2-3):(1.5-2.5).

3. The preparation method according to claim 2, characterized in that, The volume ratio of N,N-dimethylformamide and methanol in the mixed solvent in step S3 is 7:1-10:1; the concentration of the Fe3O4-coated 3D flower-like double hydroxide material in the mixed solvent of N,N-dimethylformamide and methanol is 4-10 g / L.

4. The preparation method according to claim 2, characterized in that, The operation of the solvothermal method in step S1 is as follows: mixing ethylene glycol and water in a volume ratio of 4:1 to form a mixed solvent of aqueous ethylene glycol, then adding ferric chloride and anhydrous sodium acetate into the mixed solvent, so that Fe 3+ / Ac - The molar ratio is 1:3~1:7, after ultrasonic treatment for 10-40 min, the solution is transferred to a stainless steel autoclave lined with polytetrafluoroethylene, and reacted at 150~400℃ for 6~15 h; after cooling, centrifugation, and continuous washing with water and ethanol, Fe3O4 nanoparticles are obtained.

5. Use of the magnetic solid phase extraction material for the extraction and enrichment of organophosphorus flame retardants according to claim 1, characterized in that, The extraction and enrichment of the organic phosphorus-based flame retardant.

6. Use according to claim 5, characterized in that, The extraction and enrichment of the organic phosphorus-based flame retardant comprises the following steps: The magnetic solid-phase extraction material is added to the water sample to be tested, so that the concentration of the magnetic solid-phase extraction material is 0.1-0.9 g / L, the pH value is adjusted to 6-9, the magnetic solid-phase extraction material is fully adsorbed under the action of ultrasonic waves, and the magnetic solid-phase extraction material is separated from the water sample under the action of an external magnetic field, and the supernatant is discarded.

7. Use according to claim 5 or 6, characterized in that, The detection process after enrichment is as follows: acetonitrile eluent is added to the adsorbed magnetic solid-phase extraction material, the desorption solution obtained is filtered, and high performance liquid chromatography-ultraviolet detection analysis is performed.

8. Use according to claim 7, characterized in that, Liquid chromatography analysis uses a Sun Fire® C18 chromatographic column; the mobile phase A is water containing 0.1% formic acid, and the mobile phase B is methanol containing 0.1% formic acid, the A / B phase is eluted in a volume ratio of 1:9, the column temperature is 35℃, the flow rate is 1.0 mL / min, the injection amount is 10 μL, and the detection wavelength is 210 nm.

9. Use according to claim 5, characterized in that, The organic phosphorus-based flame retardant includes triphenyl phosphate, tricresyl phosphate, 2-ethylhexyl diphenyl phosphate, resorcinol tetraphenyl diphosphate and bisphenol A bis(diphenyl phosphate).

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