Solid-phase extraction disc and preparation process by electrostatic spinning method

Abstract

The invention relates to the technical field of extraction separation, and discloses a solid-phase extraction disc and an electrostatic spinning method preparation process, the solid-phase extraction disc comprises a base material formed by coaxial electrospinning, the base material is a fiber with a core-sheath structure, a core layer of the fiber contains an adsorbent material, a sheath layer of the fiber is a polymer, and the core layer of the fiber is a porous material. And the sheath layer has a porous structure to expose the adsorbent material of the core layer. In the preparation process of the solid-phase extraction disc, an adsorbent material is wrapped in a sheath layer by adopting a coaxial electrospinning process, and the adsorbent material in the sheath layer is exposed by forming a porous structure on the sheath layer, so that the basic function of extraction and adsorption is achieved; meanwhile, the adsorbent material and the sheath layer are mutually fixed through the embedded structure, so that the bonding strength of the adsorbent material on the fiber can be ensured, and the problem of falling off of the adsorbent material is avoided; on the other hand, the adsorbent material and the sheath layer are formed simultaneously, so that the problems of agglomeration and base material pore blockage easily caused by impregnation of the loaded adsorbent material are avoided.

Description

Technical Field

[0001] This application relates to the technical field of extraction, and particularly to a solid-phase extraction disk and a preparation process by electrospinning method. Background Art

[0002] A solid-phase extraction disk (Solid Phase Extraction Disk, abbreviated as SPE disk) is a thin-layer solid-phase extraction medium used for sample pretreatment, and is widely used in the separation, enrichment, and purification of target compounds in complex samples in the fields of environment, food, pharmaceuticals, etc. Its material usually uses fibers as an inert support matrix and is loaded with adsorbents. Commonly used fibers include glass fibers and polymer fibers.

[0003] Generally speaking, the method of loading adsorbents on a solid-phase extraction disk is to immerse the substrate in an adsorbent suspension and then dry it so that the adsorbent is fixed in the fiber gaps. However, for some emerging nanoparticle-based adsorbent materials (such as metal-organic frameworks), due to factors such as the surface energy, van der Waals force, and electrostatic interaction of the nanoparticles themselves, agglomeration often occurs during impregnation, resulting in few adsorption sites inside the SPE disk and blockage of the pores of the substrate; on the other hand, there will also be a problem of binding force when the adsorbent material is loaded through the impregnation process, and the adsorbent material is likely to fall off from the substrate. Summary of the Invention

[0004] In order to overcome the problems of easy agglomeration and poor binding force resulting in shedding when nanoparticle-based adsorbent materials are applied to solid-phase extraction disks, this application provides a solid-phase extraction disk and a preparation process by electrospinning method.

[0005] In the first aspect, this application provides a solid-phase extraction disk, adopting the following technical solution: The solid-phase extraction disk includes a substrate formed by coaxial electrospinning. The substrate is a core-sheath structure fiber. The core layer of the fiber contains an adsorbent material, the sheath layer of the fiber is a polymer, and the sheath layer has a pore structure to expose the adsorbent material in the core layer.

[0006] By adopting the above technical solution, during the preparation of the solid-phase extraction disk, the coaxial electrospinning process is used to wrap the adsorbent material inside the sheath layer, and a pore structure is formed on the sheath layer to expose the adsorbent material inside the sheath layer, thereby achieving its basic function of extraction and adsorption. However, at the same time, since the adsorbent material and the sheath layer are fixed to each other through an interlocking structure, it can not only ensure the binding strength of the adsorbent material on the fiber and avoid the problem of its shedding; on the other hand, the adsorbent material and the sheath layer are formed simultaneously, avoiding the problems of agglomeration and blockage of the substrate pores easily caused by impregnating and loading the adsorbent material.

[0007] Optionally, the adsorbent material includes at least one of magnetic nanoparticles, metal-organic frameworks, covalent organic frameworks, molecularly imprinted polymers, antibodies, aptamers, and enzymes.

[0008] By adopting the above technical solution, the selectivity and adsorption capacity of the solid-phase extraction disk are improved by utilizing the high specific surface area or adsorption selectivity of the nanoparticles.

[0009] Optionally, the polymer includes at least one of polyacrylonitrile, polyvinylidene fluoride, polyurethane, and polystyrene.

[0010] By adopting the above technical solution, a solid-phase extraction disk with excellent performance can be prepared by using the polymer in combination with the electrospinning process.

[0011] In a second aspect, the present application provides an electrospinning preparation process, adopting the following technical solution: An electrospinning preparation process, which is used for any of the above-mentioned solid-phase extraction disks, and the preparation process includes the following steps: (1) Prepare a core layer solution and a sheath layer solution respectively; (2) Use a coaxial needle to extrude core-sheath fibers through a coaxial electrospinning process to form a substrate, and the inner layer of the coaxial needle conveys the core layer solution, and the outer layer conveys the sheath layer solution; (3) Treat the formed substrate to form a porous structure on the sheath layer of the core-sheath fiber to expose the internal adsorbent material.

[0012] In an embodiment, for different adsorbent materials, the core layer solution is also different, and it can be a solution, a suspension or a colloid. For example, ZIF-8 is generally prepared as a suspension.

[0013] By adopting the above technical solution, the core layer solution and the sheath layer solution are extruded into core-sheath fibers through the coaxial electrospinning process to form a substrate, ensuring that the adsorbent material inside the formed substrate is loaded through an interlocking structure, thereby ensuring the bonding strength of the adsorbent material to prevent it from falling off; on the other hand, a post-treatment process (pore-forming process) is also used to open holes in the sheath layer to expose the adsorbent material inside the sheath layer to meet the basic function of extraction and adsorption of the solid-phase extraction disk.

[0014] Optionally, the method for preparing the core layer solution in step (1) is: adding the adsorbent material to DMF and performing ultrasonic treatment to form a suspension, and the surface of the adsorbent material is modified with amino groups; the method for preparing the sheath layer solution in step (1) is: dissolving the polymer and carboxylated PEG in DMF and stirring until completely dissolved.

[0015] By adopting the above technical solution, by utilizing the difference in the interaction between the surface-modifying group amino group of the adsorbent material and the polymer / solvent system of the sheath layer, the amino group and the carboxyl group generate ionic bonding through electrostatic attraction, enabling the carboxylated PEG to selectively adsorb around the adsorbent material. Subsequently, water preferentially penetrates at the adsorption sites and triggers the glass transition of the polymer segments, solidifying the pores, and the connected pores form a permeable pore structure.

[0016] Optionally, the method for treating the formed substrate in step (3) is as follows: (3-1) Place the substrate in an environment of 85% RH and keep it for more than 30 min; (3-2) Transfer the substrate to deionized water for infiltration for 1.5 h, take it out and dry it.

[0017] By adopting the above technical solution, through a controllable humidity environment, local phase separation is preferentially induced at the adsorbent material-polymer interface, thereby forming pores around the adsorbent material particles while avoiding excessive phase separation in other regions of the fiber. Water vapor will preferentially adsorb in the carboxylated PEG enrichment area, forming a local high-humidity microenvironment, and based on the chemical potential gradient at the adsorbent material-polymer interface, water molecules diffuse into the interface area to trigger local phase separation of the polymer and the solvent; at the same time, water as a non-solvent reduces the solubility of the polymer in the solvent, resulting in the precipitation of solvent segments around the adsorbent material, forming a microporous-mesoporous structure.

[0018] The water vapor treatment is mild and controllable, avoiding the collapse of the overall fiber due to the penetration of a large amount of water.

[0019] Optionally, after step (3-2), it further includes: (3-3) Transfer the substrate to an acetone / water mixture for soaking for 10 - 30 min, take it out, wash it with water and dry it.

[0020] By adopting the above technical solution, it plays a slight etching role in forming the microporous-mesoporous structure, thereby achieving the purpose of pore expansion, improving the exposed area of the adsorbent material, and further improving the extraction effect of the solid-phase extraction disk.

[0021] Optionally, in step (2), the flow rate ratio of the core layer solution to the sheath layer solution is 1:(3 - 10), and the voltage is 10 - 20 kV.

[0022] By adopting the above technical solution, the core layer solution and the sheath layer solution can be drawn into uniform core-sheath fibers, avoiding problems such as breakage and perforation of the core and sheath layers.

[0023] In summary, the present application includes at least one of the following beneficial technical effects: (1) The core layer solution and the sheath layer solution are extruded into core-sheath fibers through a coaxial electrospinning process to form a substrate, ensuring that the adsorbent material inside the formed substrate is loaded through an interlocking structure, thereby ensuring the bonding strength of the adsorbent material to avoid its detachment. On the other hand, post-treatment processes are also used to open pores on the sheath layer to expose the adsorbent material inside the sheath layer to meet the basic function of extraction and adsorption of the solid-phase extraction disk. (2) Utilize the difference in the interaction between the surface-modifying group amino group of the adsorbent material and the polymer / solvent system of the sheath layer. The amino group and the carboxyl group generate an ionic bond through electrostatic attraction, enabling the carboxylated PEG to selectively adsorb around the adsorbent material. Then, water preferentially penetrates at the adsorption sites and triggers the glass transition of the polymer chain segments, curing the pores. The connected pores form a permeable pore structure, thereby achieving the purpose of directional pore formation. On the one hand, it can expose as much adsorbent material as possible, and on the other hand, it can avoid pore formation in other parts of the fiber and reduce the strength of the substrate. Specific embodiments

[0024] The embodiments of the present application are described in detail below.

[0025] In the description of this specification, the description with reference to the terms "certain embodiments", "one embodiment", "some embodiments", "schematic embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiments or examples are included in at least one embodiment or example of the present application. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiments or examples. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0026] Polyacrylonitrile was purchased from Shanghai Haohong Biopharmaceutical Technology Co., Ltd., CAS No. 25014-41-9; ZIF-8 was purchased from Shanghai Huayuan Century Trading Co., Ltd., CAS No. 59061-53-9; ZIF-67 was purchased from Shanghai Huayuan Century Trading Co., Ltd., CAS No. 46201-07-4; HOOC-PEG-COOH was purchased from Xiamen Syno Biological Co., Ltd., CAS No. 39927-08-7, with a molecular weight of 4k.

[0027] Raw materials and reagents not specifically described below can also be purchased commercially.

[0028] Example 1. This example provides a solid-phase extraction disk, which includes a substrate of polyacrylonitrile. The substrate is loaded with a metal-organic framework ZIF-8 inside. The substrate is a core-sheath structured fiber. The core layer of the fiber is ZIF-8, and the sheath layer of the fiber is acrylonitrile. Moreover, there are pore-like structures on the sheath layer to expose ZIF-8.

[0029] Detected by field emission scanning electron microscopy, the fiber diameter of the substrate is 400 ± 60 nm; detected by transmission electron microscopy, the core layer diameter accounts for 15%, and the loading amount of ZIF-8 is 20 wt%.

[0030] Example 2. This example provides a solid-phase extraction disk, which includes a substrate of polyvinylidene fluoride. The substrate is loaded with a metal-organic framework ZIF-67 inside. The substrate is a core-sheath structured fiber. The core layer of the fiber is ZIF-67, and the sheath layer of the fiber is polyvinylidene fluoride. Moreover, there are pore-like structures on the sheath layer to expose ZIF-67.

[0031] Detected by field emission scanning electron microscopy, the fiber diameter of the substrate is 380 ± 50 nm; detected by transmission electron microscopy, the core layer diameter accounts for 13%, and the loading amount of ZIF-8 is 18 wt%.

[0032] Preparation Example 1 Prepare the core layer solution Disperse ZIF-8 (100 mg) in ethanol (20 mL), add APTES (3-aminopropyltriethoxysilane, 50 μL); reflux at 70 °C for 6 h, and wash by ethanol centrifugation 3 times to obtain 1.5 mmol -NH2 / g amino-modified ZIF-8.

[0033] Add the amino-modified ZIF-8 (20 mg) to DMF (5 mL), and treat it by ultrasonic wave for 30 min (in an ice bath) to form a suspension.

[0034] Prepare the sheath layer solution Dissolve PAN (10 wt%) and HOOC-PEG-COOH (10 mg) in DMF, and stir for 12 h until completely dissolved.

[0035] Prepare the fiber membrane Inject the sheath layer solution and the core layer solution into a syringe, install the needle (inner needle 27G, outer needle 18G) and remove the air bubbles; At 40% RH, the electrospinning voltage is 15 kV, the receiving distance is 15 cm, the core layer flow rate is 0.1 mL / h, the sheath layer flow rate is 0.5 mL / h, and the fiber membrane is obtained by electrospinning.

[0036] Fiber pore formation Place the fiber membrane in an environment of 85% RH and keep it for 30 min; Then transfer the fiber membrane to deionized water and soak it for 1 h, take it out and dry it. Finally, transfer the fiber membrane to the acetone / water mixture and soak it for 10 min, take it out, wash it with water and dry it.

[0037] Preparation Example 2 Prepare the core layer solution Add ZIF-8 (20 mg) to DMF (5 mL) and treat it by ultrasonic for 30 min (in an ice bath) to form a suspension.

[0038] Prepare the sheath layer solution Dissolve PAN (10 wt%) in DMF and stir for 12 h until completely dissolved.

[0039] Prepare the fiber membrane Inject the sheath layer solution and the core layer solution into a syringe, install the needle (inner needle 27G, outer needle 18G) and remove the air bubbles; At 40% RH, the electrospinning voltage is 15 kV, the receiving distance is 15 cm, the core layer flow rate is 0.1 mL / h, the sheath layer flow rate is 0.5 mL / h, and the fiber membrane is obtained by electrospinning.

[0040] Fiber pore formation Place the fiber membrane in an environment of 85% RH and keep it for 30 min; Then transfer the fiber membrane to deionized water and soak it for 1 h, take it out and dry it. Finally, transfer the fiber membrane to the acetone / water mixture and soak it for 10 min, take it out, wash it with water and dry it.

[0041] Comparative Example 1 Prepare the core layer solution Add ZIF-8 (20 mg) to DMF (5 mL) and treat it by ultrasonic for 30 min (in an ice bath) to form a suspension.

[0042] Prepare the sheath layer solution Dissolve PAN (10 wt%) in DMF and stir for 12 h until completely dissolved.

[0043] Prepare the fiber membrane Inject the sheath layer solution and the core layer solution into a syringe, install the needle (inner needle 27G, outer needle 18G) and remove the air bubbles; At 40% RH, the electrospinning voltage is 15 kV, the receiving distance is 15 cm, the core layer flow rate is 0.1 mL / h, the sheath layer flow rate is 0.5 mL / h, and the fiber membrane is obtained by electrospinning.

[0044] The solid-phase extraction disks of Preparation Example 1, Preparation Example 2 and Comparative Example 1 were subjected to performance tests. The test conditions were that bisphenol A passed through a 47-mm solid-phase extraction disk at a flow rate of 12 mL / min under a pressure of 1 bar, and its adsorption capacity was detected. The adsorption capacity of Preparation Example 1 was 87 mg / g, the adsorption capacity of Preparation Example 2 was 56 mg / g, and the adsorption capacity of Comparative Example 1 was 28 mg / g. By comparison, it can be seen that during the preparation of the solid-phase extraction disk in Comparative Example 1, no fiber pore-forming treatment was carried out. Therefore, the adsorption relied only on the pore conditions of the solid-phase extraction disk itself, so the adsorption capacity was much lower than that of Preparation Example 1. Although fiber pore-forming treatment was carried out in Preparation Example 2, the core layer solution and the sheath layer solution were not treated. Therefore, PEG randomly dissolved during pore formation, resulting in the fact that some of the internal ZIF-8 was not exposed. Therefore, the porosity of the mesopores did not increase significantly, and the adsorption capacity was also lower than that of Preparation Example 1.

[0045] Preparation Example 3 Prepare the core layer solution Disperse ZIF-8 (100 mg) in ethanol (20 mL), add APTES (3-aminopropyltriethoxysilane, 50 μL); reflux at 70 °C for 6 h, and wash by centrifugation with ethanol 3 times to obtain 1.5 mmol -NH2 / g amino-modified ZIF-8.

[0046] Add the amino-modified ZIF-8 (20 mg) to DMF (5 mL), and treat it by ultrasonic wave for 30 min (in an ice bath) to form a suspension.

[0047] Prepare the sheath layer solution Dissolve PAN (10 wt%) and HOOC-PEG-COOH (10 mg) in DMF, and stir for 12 h until completely dissolved.

[0048] Prepare the fiber membrane Inject the sheath layer solution and the core layer solution into a syringe, install the needle (inner needle 27G, outer needle 18G) and remove the air bubbles; At 40% RH, the electrospinning voltage is 15 kV, the receiving distance is 15 cm, the core layer flow rate is 0.1 mL / h, and the sheath layer flow rate is 0.5 mL / h. The fiber membrane is obtained by electrospinning.

[0049] Fiber pore formation Transfer the fiber membrane to deionized water and soak it for 1 h, then take it out and dry it; Finally, transfer the fiber membrane to an acetone / water mixture and soak it for 10 min, then take it out, wash it with water and dry it.

[0050] Preparation Example 4 Prepare the core layer solution Disperse ZIF-8 (100 mg) in ethanol (20 mL), and add APTES (3-aminopropyltriethoxysilane, 50 μL); reflux at 70 °C for 6 h, and wash by centrifugation with ethanol three times to obtain amino-modified ZIF-8 with 1.5 mmol -NH2 / g.

[0051] Add amino-modified ZIF-8 (20 mg) to DMF (5 mL), and treat it by ultrasonic for 30 min (in an ice bath) to form a suspension.

[0052] Prepare the sheath solution Dissolve PAN (10 wt%) and HOOC-PEG-COOH (10 mg) in DMF, and stir for 12 h until completely dissolved.

[0053] Prepare the fiber membrane Inject the sheath solution and the core solution into a syringe, install the needle (inner needle 27G, outer needle 18G) and remove the air bubbles; At 40% RH, the electrospinning voltage is 15 kV, the receiving distance is 15 cm, the core layer flow rate is 0.1 mL / h, and the sheath layer flow rate is 0.5 mL / h. Obtain the fiber membrane by electrospinning.

[0054] Pore formation of the fiber Transfer the fiber membrane to deionized water and soak for 1.5 h, then take it out and dry. Finally, transfer the fiber membrane to the acetone / water mixture and soak for 10 min, then take it out, wash with water and dry.

[0055] Preparation Example 5 Prepare the core solution Disperse ZIF-8 (100 mg) in ethanol (20 mL), and add APTES (3-aminopropyltriethoxysilane, 50 μL); reflux at 70 °C for 6 h, and wash by centrifugation with ethanol three times to obtain amino-modified ZIF-8 with 1.5 mmol -NH2 / g.

[0056] Add amino-modified ZIF-8 (20 mg) to DMF (5 mL), and treat it by ultrasonic for 30 min (in an ice bath) to form a suspension.

[0057] Prepare the sheath solution Dissolve PAN (10 wt%) and HOOC-PEG-COOH (10 mg) in DMF, and stir for 12 h until completely dissolved.

[0058] Prepare the fiber membrane Inject the sheath solution and the core solution into a syringe, install the needle (inner needle 27G, outer needle 18G) and remove the air bubbles; At 40% RH, the electrospinning voltage is 15 kV, the receiving distance is 15 cm, the core layer flow rate is 0.1 mL / h, the sheath layer flow rate is 0.5 mL / h, and a fibrous membrane is obtained by electrospinning.

[0059] Fiber pore formation Place the fibrous membrane in an environment of 80% RH and keep it for 30 min; Then transfer the fibrous membrane to deionized water for infiltration for 1 h, take it out and dry it; Finally, transfer the fibrous membrane to an acetone / water mixture for soaking for 10 min, take it out, wash it with water and dry it.

[0060] Preparation Example 6 Prepare the core layer solution Disperse ZIF-8 (100 mg) in ethanol (20 mL), add APTES (3-aminopropyltriethoxysilane, 50 μL); reflux at 70 °C for 6 h, and wash by centrifugation with ethanol 3 times to obtain 1.5 mmol -NH2 / g amino-modified ZIF-8.

[0061] Add the amino-modified ZIF-8 (20 mg) to DMF (5 mL), and treat it by ultrasonic for 30 min (in an ice bath) to form a suspension.

[0062] Prepare the sheath layer solution Dissolve PAN (10 wt%) and HOOC-PEG-COOH (10 mg) in DMF, and stir for 12 h until completely dissolved.

[0063] Prepare the fibrous membrane Inject the sheath layer solution and the core layer solution into a syringe, install the needle (inner needle 27G, outer needle 18G) and remove the air bubbles; At 40% RH, the electrospinning voltage is 15 kV, the receiving distance is 15 cm, the core layer flow rate is 0.1 mL / h, the sheath layer flow rate is 0.5 mL / h, and a fibrous membrane is obtained by electrospinning.

[0064] Fiber pore formation Place the fibrous membrane in an environment of 85% RH and keep it for 20 min; Then transfer the fibrous membrane to deionized water for infiltration for 1 h, take it out and dry it; Finally, transfer the fibrous membrane to an acetone / water mixture for soaking for 10 min, take it out, wash it with water and dry it.

[0065] The solid-phase extraction disks prepared in Preparation Examples 3 to 6 were subjected to performance testing. The testing conditions were that bisphenol A passed through a 47-mm solid-phase extraction disk at a flow rate of 12 mL / min under a pressure of 1 bar, and its adsorption capacity was detected. The adsorption capacity of Preparation Example 3 was 72 mg / g, that of Preparation Example 4 was 76 mg / g, that of Preparation Example 5 was 78 mg / g, and that of Preparation Example 6 was 80 mg / g.

[0066] By comparison, it can be seen that in Preparation Example 3, the fiber membrane was not subjected to high-humidity retention treatment, and its adsorption capacity decreased significantly; combined with Preparation Example 4, it was found that although the infiltration time of deionized water was extended, the adsorption effect could not be completely improved to that of Preparation Example 1, indicating that the high-humidity retention treatment of the fiber membrane is beneficial to locally create pores around ZIF-8 and expose ZIF-8 as much as possible to improve the adsorption effect; in Preparation Examples 5 and 6, the adsorption capacity was also lower than that of Preparation Example 1. It can be seen that both the time and humidity conditions of the high-humidity retention treatment will affect the adsorption performance of the prepared solid-phase extraction disk, and the optimal relative humidity condition is 85% RH, and the time is controlled at 30 min.

[0067] Preparation Example 7 Prepare the core layer solution Disperse ZIF-8 (100 mg) in ethanol (20 mL), and add APTES (3-aminopropyltriethoxysilane, 50 μL); reflux at 70 °C for 6 h, and wash by centrifugation with ethanol 3 times to obtain 1.5 mmol -NH2 / g amino-modified ZIF-8.

[0068] Add the amino-modified ZIF-8 (20 mg) to DMF (5 mL), and ultrasonically treat it for 30 min (in an ice bath) to form a suspension.

[0069] Prepare the sheath layer solution Dissolve PAN (10 wt%) and HOOC-PEG-COOH (10 mg) in DMF, and stir for 12 h until completely dissolved.

[0070] Prepare the fiber membrane Inject the sheath layer solution and the core layer solution into a syringe, install the needle (inner needle 27G, outer needle 18G) and remove the air bubbles; At 40% RH, the electrospinning voltage is 15 kV, the receiving distance is 15 cm, the core layer flow rate is 0.2 mL / h, the sheath layer flow rate is 0.5 mL / h, and the fiber membrane is obtained by electrospinning.

[0071] Fiber pore formation Place the fiber membrane in an environment of 85% RH and keep it for 30 min; Then transfer the fiber membrane to deionized water for infiltration for 1 h, take it out and dry it; Finally, transfer the fiber membrane to an acetone / water mixture and soak for 10 min, then take it out, wash with water and dry.

[0072] Preparation Example 8 Prepare the core layer solution Disperse ZIF-8 (100 mg) in ethanol (20 mL), add APTES (3-aminopropyltriethoxysilane, 50 μL); reflux at 70 °C for 6 h, and wash by centrifugation with ethanol 3 times to obtain 1.5 mmol -NH2 / g amino-modified ZIF-8.

[0073] Add the amino-modified ZIF-8 (20 mg) to DMF (5 mL), and treat it by ultrasonic for 30 min (in an ice bath) to form a suspension.

[0074] Prepare the sheath layer solution Dissolve PAN (10 wt%) and HOOC-PEG-COOH (10 mg) in DMF, and stir for 12 h until completely dissolved.

[0075] Prepare the fiber membrane Inject the sheath layer solution and the core layer solution into a syringe, install the needle (inner needle 27G, outer needle 18G) and remove the air bubbles; At 40% RH, the electrospinning voltage is 15 kV, the receiving distance is 15 cm, the core layer flow rate is 0.2 mL / h, the sheath layer flow rate is 0.6 mL / h, and the fiber membrane is obtained by electrospinning.

[0076] Fiber pore formation Place the fiber membrane in an environment of 85% RH and keep it for 30 min; Then transfer the fiber membrane to deionized water and soak for 1 h, take it out and dry; Finally, transfer the fiber membrane to an acetone / water mixture and soak for 10 min, take it out, wash with water and dry.

[0077] Preparation Example 9 Prepare the core layer solution Disperse ZIF-8 (100 mg) in ethanol (20 mL), add APTES (3-aminopropyltriethoxysilane, 50 μL); reflux at 70 °C for 6 h, and wash by centrifugation with ethanol 3 times to obtain 1.5 mmol -NH2 / g amino-modified ZIF-8.

[0078] Add the amino-modified ZIF-8 (20 mg) to DMF (5 mL), and treat it by ultrasonic for 30 min (in an ice bath) to form a suspension.

[0079] Prepare the sheath layer solution PAN (10 wt%) and HOOC-PEG-COOH (10 mg) were dissolved in DMF and stirred for 12 h until completely dissolved.

[0080] Preparation of fiber membrane Inject the sheath solution and core solution into the syringe, install the needle (inner needle 27G, outer needle 18G) and remove the bubbles; The fiber membrane was obtained by electrospinning at 40% RH, 15 kV electrospinning voltage, 15 cm receiving distance, 0.2 mL / h core layer flow rate, 0.7 mL / h sheath layer flow rate.

[0081] Fiber pores The fiber membrane was placed in an 85% RH environment for 30 min; Then transfer the fiber membrane to deionized water and soak it for 1 h, then take it out and dry it; Finally, the fiber membrane was moved to an acetone / water mixture and soaked for 10 minutes, then taken out, washed and dried.

[0082] The solid phase extraction disks of Preparation Examples 7 to 9 were subjected to performance tests, and the test conditions were that 12 mL / min of bisphenol A passed through a 47 mm solid phase extraction disk under a pressure of 1 bar, and the adsorption amount was detected. The adsorption amount of Preparation Example 7 was 64 mg / g, the adsorption amount of Preparation Example 8 was 92 mg / g, and the adsorption amount of Preparation Example 9 was 90 mg / g.

[0083] By comparison, it can be seen that in Preparation Example 7, the delivery flow rate of the core solution was adjusted from 0.1 mL / h to 0.2 mL / h, in order to increase the loading amount of ZIF-8 on the fiber membrane, but the adsorption effect of the actual test was much lower than that of Preparation Example 1. Through SEM scanning electron microscopy observation, it was found that there were more fractures in the fibers before pore formation, which led to the leakage of part of the ZIF-8 in the sheath solution from the fracture during the molding process, and detached from the fiber membrane in the subsequent pore formation process, resulting in a significant decrease in the adsorption amount; while in Preparation Example 8, the delivery flow rate of the sheath solution was slightly increased to 0.6 mL / h, under this condition, the delivery flow rate ratio of the core solution to the sheath solution is 1:3, and it is found that the adsorption amount is improved to a certain extent compared with Preparation Example 1. In Preparation Example 9, the delivery flow rate of the sheath solution is slightly increased to 0.7mL / h, and the adsorption amount is still improved compared with Preparation Example 1, indicating that controlling the delivery flow rate ratio of the core solution to the sheath solution plays a vital role in maintaining the integrity and continuity of the fiber, so that when the loading amount of ZIF-8 is appropriately increased, ZIF-8 will not be separated due to fiber breakage, ensuring the adsorption effect of the solid phase extraction disk. Of course, the greater the delivery flow rate of the sheath solution, the less ZIF-8 will be loaded on the solid phase extraction disk, which will also affect the adsorption effect of the solid phase extraction disk, so it is recommended that the delivery flow rate ratio of the core solution to the sheath solution is 1: (3~10).

[0084] Preparation Example 10 Preparation of the core layer solution Disperse ZIF-8 (100 mg) in ethanol (20 mL), and add APTES (3-aminopropyltriethoxysilane, 50 μL); reflux at 70 °C for 6 h, and wash by centrifugation with ethanol three times to obtain 2 mmol -NH2 / g of amino-modified ZIF-8.

[0085] Add the amino-modified ZIF-8 (20 mg) to DMF (5 mL), and treat it by ultrasonic wave for 30 min (in an ice bath) to form a suspension.

[0086] Preparation of the sheath layer solution Dissolve PAN (10 wt%) and HOOC-PEG-COOH (10 mg) in DMF, and stir for 12 h until completely dissolved.

[0087] Preparation of the fiber membrane Inject the sheath layer solution and the core layer solution into a syringe, install the needle (inner needle 27G, outer needle 18G), and remove the air bubbles; At 40% RH, the electrospinning voltage is 15 kV, the receiving distance is 15 cm, the core layer flow rate is 0.2 mL / h, the sheath layer flow rate is 0.7 mL / h, and the fiber membrane is obtained by electrospinning.

[0088] Fiber pore formation Place the fiber membrane in an environment of 85% RH for 30 min; Then transfer the fiber membrane to deionized water for infiltration for 1 h, take it out and dry it; Finally, immerse the fiber membrane in the acetone / water mixture for 10 min, take it out, wash it with water and dry it.

[0089] Preparation Example 11 Preparation of the core layer solution Disperse ZIF-8 (100 mg) in ethanol (20 mL), and add APTES (3-aminopropyltriethoxysilane, 50 μL); reflux at 70 °C for 6 h, and wash by centrifugation with ethanol three times to obtain 2.5 mmol -NH2 / g of amino-modified ZIF-8.

[0090] Add the amino-modified ZIF-8 (20 mg) to DMF (5 mL), and treat it by ultrasonic wave for 30 min (in an ice bath) to form a suspension.

[0091] Preparation of the sheath layer solution Dissolve PAN (10 wt%) and HOOC-PEG-COOH (10 mg) in DMF, and stir for 12 h until completely dissolved.

[0092] Preparation of the fiber membrane Inject the sheath solution and the core solution into a syringe, install the needle (inner needle 27G, outer needle 18G), and remove air bubbles. At 40% RH, the electrospinning voltage is 15 kV, the receiving distance is 15 cm, the core layer flow rate is 0.2 mL / h, and the sheath layer flow rate is 0.7 mL / h. An electrospun fiber membrane is obtained.

[0093] Fiber pore formation Place the fiber membrane in an environment of 85% RH and keep it for 30 min. Then transfer the fiber membrane to deionized water for infiltration for 1 h, take it out and dry it. Finally, transfer the fiber membrane to an acetone / water mixture for soaking for 10 min, take it out, wash it with water and dry it.

[0094] Preparation Example 12 Prepare the core solution Disperse ZIF-8 (100 mg) in ethanol (20 mL), add APTES (3-aminopropyltriethoxysilane, 50 μL); reflux at 70 °C for 6 h, and wash by centrifugation with ethanol 3 times to obtain 2.5 mmol -NH2 / g of amino-modified ZIF-8.

[0095] Add the amino-modified ZIF-8 (20 mg) to DMF (5 mL), and treat it by ultrasonic for 30 min (in an ice bath) to form a suspension.

[0096] Prepare the sheath solution Dissolve PAN (10 wt%) and HOOC-PEG-COOH (10 mg) in DMF, and stir for 12 h until completely dissolved.

[0097] Prepare the fiber membrane Inject the sheath solution and the core solution into a syringe, install the needle (inner needle 27G, outer needle 18G), and remove air bubbles. At 40% RH, the electrospinning voltage is 15 kV, the receiving distance is 15 cm, the core layer flow rate is 0.2 mL / h, and the sheath layer flow rate is 0.7 mL / h. An electrospun fiber membrane is obtained.

[0098] Fiber pore formation Place the fiber membrane in an environment of 80% RH and keep it for 30 min. Then transfer the fiber membrane to deionized water for infiltration for 1 h, take it out and dry it. Finally, transfer the fiber membrane to an acetone / water mixture for soaking for 10 min, take it out, wash it with water and dry it.

[0099] The solid-phase extraction disks prepared in Preparation Examples 10 to 12 were subjected to performance tests. The test conditions were that bisphenol A passed through a 47-mm solid-phase extraction disk at a pressure of 1 bar at a flow rate of 12 mL / min, and its adsorption capacity was detected. The adsorption capacity of Preparation Example 10 was 93 mg / g, that of Preparation Example 11 was 68 mg / g, and that of Preparation Example 12 was 88 mg / g.

[0100] By comparison, in Preparation Example 10, the amino modification density of ZIF-8 was increased to 2 mmol -NH2 / g, which could further improve the migration and enrichment degree of carboxylated PEG around ZIF-8, and thus was conducive to pore formation and exposure of ZIF-8; in Preparation Example 11, the amino modification density of ZIF-8 was further increased to 2.5 mmol -NH2 / g, but it was found that the adsorption capacity decreased significantly in the reverse direction. Through SEM observation, it was found that the fiber before pore formation had good continuous integrity, but after subsequent pore formation, through SEM observation, it was found that there were many fractures in the fiber, which led to the exposure and shedding of ZIF-8. At the same time, the fiber fracture would also directly affect the strength of the solid-phase extraction disk, resulting in problems such as out-of-control permeability, collapse of the fiber stacking structure, and blockage of the mass transfer channel during use; in Preparation Example 12, by reducing the relative humidity of fiber pore formation, the adsorption capacity was increased to 88 mg / g again. Through SEM observation, it was found that there was no fiber fracture after pore formation, but due to the pore formation effect being inferior to that of Preparation Example 10, the exposure degree of ZIF-8 was slightly lower, and the adsorption capacity was also slightly lower than that of Preparation Example 10. It shows that by increasing the amino modification density, the migration and enrichment degree of carboxylated PEG around ZIF-8 can be improved, and thus the pore formation effect can be improved, but too high an amino modification density will lead to fiber fracture during subsequent pore formation, and the amino modification density should not be too low, which is not conducive to local pore formation around ZIF-8. Generally speaking, the amino modification density of ZIF-8 is controlled at 1-2 mmol -NH2 / g.

Claims

1. A solid phase extraction disk, characterized in that The invention comprises a substrate formed by coaxial electrospinning. The substrate is a fiber with a core-sheath structure. The core layer of the fiber contains an adsorbent material. The sheath layer of the fiber is a polymer. The sheath layer has a pore structure to expose the adsorbent material of the core layer.

2. The solid phase extraction disk according to claim 1, characterized in that: The adsorbent material includes at least one of magnetic nanoparticles, metal-organic frameworks, covalent organic frameworks, molecularly imprinted polymers, antibodies, aptamers and enzymes.

3. The solid phase extraction disk according to claim 1, characterized in that: The polymer includes at least one of polyacrylonitrile, polyvinylidene fluoride, polyurethane and polystyrene.

4. The electrospinning method is characterized in that: The electrospinning preparation process is used to prepare the solid phase extraction disk according to any one of claims 1 to 3, and the preparation process comprises the following steps: (1) preparing a core layer solution and a sheath layer solution respectively; (2) using a coaxial needle to stretch out core-sheath fibers through a coaxial electrospinning process to form a substrate, wherein the inner layer of the coaxial needle transports the core layer solution and the outer layer transports the sheath layer solution; (3) The formed substrate is treated to form a porous structure on the sheath layer of the core-sheath fiber to expose the adsorbent material inside.

5. The electrospinning preparation process according to claim 4, characterized in that: The method for preparing the core layer solution in step (1) is: adding the adsorbent material into DMF, ultrasonically treating it to form a suspension, and the surface of the adsorbent material is modified with amino groups.

6. The electrospinning preparation process according to claim 4, characterized in that: The method for preparing the sheath solution in step (1) is: dissolving the polymer and carboxylated PEG in DMF and stirring until completely dissolved.

7. The electrospinning preparation process according to claim 4, characterized in that: The method for treating the formed substrate in step (3) is: (3-1) Place the substrate in an environment with 85% RH for more than 30 min; (3-2) Transfer the substrate to deionized water and soak it for 1.5 h, then take it out and dry it.

8. The electrospinning preparation process according to claim 7, characterized in that: The step (3-2) further includes: (3-3) Transfer the substrate to an acetone / water mixture and soak for 10 to 30 min. Remove the substrate and wash it with water and dry it.

9. The electrospinning preparation process according to claim 4, characterized in that: In the step (2), the flow rate ratio of the core layer solution to the sheath layer solution is 1:(3-10), and the voltage is 10-20 kV.