Preparation method and application of novel silica powder / MOFs composite material

Abstract

The invention relates to the technical field of silica powder and MOFs compounding, in particular to a preparation method and application of a novel silica powder / MOFs composite material, and the preparation method comprises the following steps: step 1, preparing a spinning precursor solution, dispersing silica powder and MOFs powder in a solvent in proportion, and performing ultrasonic treatment to obtain a dispersion liquid; adding a polymer into the dispersion liquid to form a uniform spinning precursor solution; 2, preparing a silica powder / MOFs composite fiber membrane through electrostatic spinning; and 3, carrying out heat treatment on the prepared composite fiber membrane, or carrying out chemical crosslinking with glutaraldehyde, cleaning and drying the composite fiber membrane, and removing residual solvents and unreacted substances. The composite fiber is prepared by adopting an electrostatic spinning method, so that the problems of weak interface bonding force, limited material form, complex preparation process and single function in the prior art are solved; the composite material is applied to the field of water treatment, efficient adsorption and removal of various pollutants are achieved, and meanwhile the stability and recoverability of the material are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of the composite of silica powder and MOFs, and specifically refers to a preparation method and application of a novel silica powder / MOFs composite material. Background Art

[0002] Silica powder has a high specific surface area, high adsorption and chemical stability, and is often used as an adsorbent or carrier in water treatment. MOFs (metal-organic framework materials) have porous structures, high specific surface areas, and functionalizable properties, and can efficiently adsorb pollutants in water (such as heavy metal ions, organic dyes, drug residues, etc.). Combining silica powder with MOFs can combine the advantages of both to improve the adsorption performance, mechanical strength, and stability of the material.

[0003] The existing technologies mainly adopt in-situ growth method or mechanical mixing method. The interfacial bonding force between silica powder and MOFs is weak, which easily leads to structural collapse or performance degradation of the material during use. The reason is that the in-situ growth method is limited by the growth conditions of MOFs, and the mechanical mixing method is difficult to achieve uniform dispersion and strong interfacial bonding.

[0004] Most of the existing silica powder / MOFs composite materials are in powder or granular form, which are difficult to be directly applied to continuous water treatment systems (such as membrane separation, filtration, etc.). The reason is that the materials in powder or granular form are easy to lose and difficult to fix and recycle.

[0005] The growth of MOFs and the surface modification of silica powder have high requirements for reaction conditions (such as temperature, pH value, solvent). The in-situ growth method and surface modification method require complex process conditions and long reaction times, increasing the production cost.

[0006] The design and functionalization of the material lack diversity and are difficult to meet the needs of complex water quality treatment. As a result, the existing composite materials are mostly targeted at single pollutants (such as heavy metal ions or organic dyes) and are difficult to remove multiple pollutants simultaneously. Summary of the Invention

[0007] To overcome the problems of weak interfacial bonding force, limited material form, complex preparation process, and single function involved in the existing technologies, the present invention provides a preparation method and application of a novel silica powder / MOFs composite material. The composite fiber is prepared by electrospinning to solve the problems of weak interfacial bonding force, limited material form, complex preparation process, and single function in the existing technologies. The composite material is applied to the field of water treatment to achieve efficient adsorption and removal of multiple pollutants, while improving the stability and recyclability of the material.

[0008] The technical solution adopted by the present invention is as follows: A preparation method of a novel silica powder / MOFs composite material, comprising the following steps:

[0009] Step 1: Prepare the spinning precursor solution

[0010] Disperse silica powder and MOFs powder in a solvent in proportion, and ultrasonically treat for 30 - 60 min to obtain a uniformly dispersed dispersion;

[0011] Add the polymer to the above dispersion, with the mass ratio of polymer:silica powder:MOFs: solvent = 10:2:3:85, and stir until completely dissolved to form a uniform spinning precursor solution;

[0012] Step 2: Prepare composite fibers by electrospinning

[0013] Add the spinning precursor solution into the syringe of the electrospinning equipment;

[0014] Under the action of a high - voltage electrostatic field, the solution is stretched into fibers and deposited on the receiving device to form a silica powder / MOFs composite fiber membrane;

[0015] Step 3: Post - treatment to enhance performance

[0016] Heat - treat the prepared composite fiber membrane or perform chemical cross - linking by cross - linking with glutaraldehyde to further enhance its mechanical properties;

[0017] Wash and dry the composite fiber membrane to remove residual solvents and unreacted substances.

[0018] Furthermore, in Step 1, the mass ratio of silica powder:MOFs = 1:1.5.

[0019] Furthermore, in Step 1, the solvent is N,N - dimethylformamide (DMF) or ethanol;

[0020] The dosage of the solvent accounts for 10% of the total mass of the dispersion.

[0021] Furthermore, in Step 1, the polymer is polyacrylonitrile (PAN) or polyvinyl alcohol (PVA).

[0022] Furthermore, in Step 2, the spinning parameters set by the electrospinning equipment include a voltage of 15 - 25 kV, a receiving distance of 10 - 20 cm, and a feeding speed of 0.5 - 2 mL / h.

[0023] Furthermore, in Step 3, the heat - treatment process is as follows:

[0024] 1. Put the prepared composite fiber membrane into an oven;

[0025] 2. Set the oven temperature to 80 - 120 °C, preferably 100 °C, and the heat - treatment time to 1 - 2 hours, preferably 1.5 hours;

[0026] 3. After the heat treatment is completed, take out the fiber membrane and cool it to room temperature.

[0027] Further, in step three, the chemical cross-linking process is as follows:

[0028] Prepare the cross-linking solution: Mix the glutaraldehyde solution with ethanol, where the purity of ethanol is ≥95%, stir evenly, and the volume ratio of glutaraldehyde to ethanol is 5:95;

[0029] Add a small amount of catalyst to obtain the glutaraldehyde cross-linking solution to accelerate the cross-linking reaction;

[0030] The catalyst accounts for 0.5% (mass fraction) of the cross-linking solution;

[0031] Cross-linking treatment: Immerse the composite fiber membrane into the prepared glutaraldehyde cross-linking solution to ensure that the composite fiber membrane is completely submerged;

[0032] Use 20 mL of glutaraldehyde cross-linking solution per gram of the composite fiber membrane;

[0033] Cross-link at room temperature to 40 °C for 1.5 hours;

[0034] Washing and drying: After the cross-linking is completed, take out the composite fiber membrane, wash it several times with deionized water or ethanol to remove the unreacted glutaraldehyde and catalyst;

[0035] Dry the fiber membrane at room temperature or in an oven.

[0036] Further, the catalyst used in the chemical cross-linking process is hydrochloric acid, and the concentration of hydrochloric acid is 0.5%.

[0037] The present invention also discloses the application of a novel silica powder / MOFs composite material in the field of water treatment. Specifically, the composite fiber membrane is applied to a continuous water treatment system (such as membrane separation, filtration, etc.) to improve the practicality and recyclability of the material.

[0038] The beneficial effects achieved by the present invention with the above structure are as follows:

[0039] 1. Innovation in the composite method: The silica powder / MOFs composite fiber is prepared by electrospinning, solving the problems of weak interfacial bonding force and limited material morphology in the prior art;

[0040] 2. Process optimization: By optimizing the electrospinning parameters and post-treatment process, the preparation process is simplified, the production cost is reduced, the energy consumption is low, and it is suitable for large-scale production;

[0041] 3. Multifunctional design: By selecting different MOFs or functionalized silica powder, the multifunctionalization of the composite material is realized, with a high specific surface area and strong interfacial bonding force, meeting the requirements of complex water quality treatment;

[0042] 4. Application Expansion: High adsorption efficiency, good recyclability, suitable for continuous systems, improving the practicality and recyclability of materials;

[0043] 5. Operation and Use: Simple operation and convenient use. Specific Embodiments

[0044] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0045] Embodiment

[0046] A preparation method of a novel silica powder / MOFs composite material includes the following steps:

[0047] Step 1, preparing a spinning precursor solution

[0048] Disperse silica powder and MOFs powder in a solvent (such as N,N-dimethylformamide DMF or ethanol) according to a ratio (mass of silica powder: mass of MOFs = 1:1.5), and ultrasonically treat for 30 - 60 min to obtain a uniformly dispersed dispersion;

[0049] The dosage of the solvent accounts for 10% of the total mass of the dispersion;

[0050] Add a polymer (such as polyacrylonitrile PAN or polyvinyl alcohol PVA) to the above dispersion and stir until completely dissolved to form a uniform spinning precursor solution;

[0051] Polymer mass: dispersion mass = 2:1;

[0052] Through ultrasonic treatment and stirring, ensure the uniform dispersion of silica powder and MOFs in the solution and avoid agglomeration;

[0053] The viscosity and surface tension of the polymer solution are suitable for electrospinning, ensuring the continuity and stability of the electrospinning process;

[0054] Silica powder mass: MOFs mass: solvent mass = 10:2:3:85;

[0055] Step 2, electrospinning to prepare composite fibers

[0056] Add the spinning precursor solution to the syringe of the electrospinning equipment and set the electrospinning parameters (such as voltage 15 - 25 kV, receiving distance 10 - 20 cm, advancing speed 0.5 - 2 mL / h);

[0057] Under the action of a high-voltage electrostatic field, the solution is stretched into fibers and deposited on a receiving device (such as aluminum foil or a roller) to form a silicon micropowder / MOFs composite fiber membrane;

[0058] The electrospinning method stretches the solution into micro-nano scale fibers to form a composite fiber with a high specific surface area and a porous structure;

[0059] Silicon micropowder and MOFs are uniformly dispersed in the fiber matrix, enhancing the interfacial bonding force and improving the structural stability of the material;

[0060] Step three, post-treatment to enhance performance

[0061] The prepared composite fiber membrane is heat-treated or chemically cross-linked by cross-linking with glutaraldehyde to further enhance its mechanical properties;

[0062] The heat treatment process is as follows:

[0063] 1. Put the prepared composite fiber membrane into an oven;

[0064] 2. Set the oven temperature to 80 - 120 °C;

[0065] In one embodiment, the temperature is 100 °C;

[0066] The heat treatment time is 1 - 2 hours;

[0067] In one embodiment, the heat treatment time is 1.5 hours;

[0068] 3. After the heat treatment is completed, take out the fiber membrane and cool it to room temperature.

[0069] The chemical cross-linking process is as follows:

[0070] Prepare the cross-linking solution: Mix the glutaraldehyde solution with ethanol, where the ethanol purity ≥ 95%, stir evenly, and the volume ratio of glutaraldehyde:ethanol = 5:95;

[0071] Add a small amount of catalyst (hydrochloric acid or, with a concentration of 0.5%) to obtain a glutaraldehyde cross-linking solution to accelerate the cross-linking reaction;

[0072] The catalyst accounts for 0.5% (mass fraction) of the cross-linking solution;

[0073] Cross-linking treatment: Immerse the composite fiber membrane in the prepared glutaraldehyde cross-linking solution to ensure that the composite fiber membrane is completely immersed;

[0074] Use 20 mL of glutaraldehyde cross-linking solution per gram of composite fiber membrane;

[0075] Cross-link at room temperature to 40 °C for 1.5 hours;

[0076] Washing and Drying: After crosslinking is completed, take out the composite fiber membrane and wash it several times with deionized water or ethanol to remove unreacted glutaraldehyde and catalyst;

[0077] Dry the fiber membrane at room temperature or in an oven;

[0078] Among them, heat treatment or chemical crosslinking makes the fiber structure more dense, improving the mechanical strength and stability of the material;

[0079] The washing and drying steps ensure the purity of the material and avoid the influence of impurities on the water treatment performance.

[0080] The finally obtained composite fiber membrane has the following properties:

[0081] 1. High specific surface area and porous structure: The composite fiber has a high specific surface area and a porous structure (specific surface area ≥ 500 m 2 / g, pore size distribution is 1 - 10 nm), providing abundant adsorption sites and enhancing the adsorption capacity for pollutants;

[0082] 2. Strong interfacial bonding force: Silicon micropowder and MOFs are evenly dispersed in the fiber matrix, with strong interfacial bonding force and stable material structure;

[0083] 3. Good mechanical properties: Through heat treatment or chemical crosslinking, the composite fiber has excellent mechanical strength and durability, and the composite material has a good recycling performance (adsorption capacity retention rate ≥ 90% after 5 cycles of use);

[0084] 4. Versatility: By selecting different MOFs or functionalized silicon micropowder, the composite material can simultaneously remove multiple pollutants (such as heavy metal ions, organic dyes, drug residues, etc.), and the adsorption capacity for specific pollutants (adsorption capacity for Pb 2+ ≥ 200 mg / g, adsorption capacity for methylene blue ≥ 150 mg / g);

[0085] 5. Easy to scale up production: The electrospinning process is mature and suitable for large-scale preparation of composite fibers.

[0086] It should be noted that in this article, the term "including", "comprising" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or elements inherent to such process, method, article or device.

[0087] Although embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a novel silicon micropowder / MOFs composite material, characterized in that: Step 1: Preparation of spinning precursor solution Dispersing silicon micropowder and MOFs powder in a solvent in proportion, and ultrasonically treating them for 30 to 60 minutes to uniformly disperse them to obtain a dispersion; Adding the polymer to the above dispersion and stirring until it is completely dissolved to form a uniform spinning precursor solution; Step 2: Preparation of composite fibers by electrospinning Adding the spinning precursor solution into the syringe of the electrospinning device; Under the action of high-voltage electrostatic field, the solution is stretched into fibers and deposited on the receiving device to form a silicon micropowder / MOFs composite fiber membrane; Step 3: Post-processing to enhance performance The prepared composite fiber membrane is subjected to heat treatment or chemical cross-linking by cross-linking with glutaraldehyde; The composite fiber membrane is washed and dried to remove residual solvent and unreacted substances.

2. The method for preparing a novel silicon micropowder / MOFs composite material according to claim 1, characterized in that: The mass of the polymer: the mass of the dispersion = 2:

1.

3. The method for preparing a novel silicon micropowder / MOFs composite material according to claim 1, characterized in that: In step 1, the mass of silicon micropowder: mass of MOFs = 1:1.

5.

4. The method for preparing a novel silicon micropowder / MOFs composite material according to claim 1, characterized in that: In step 1, the solvent is N,N-dimethylformamide DMF or ethanol; The amount of the solvent accounts for 10% of the total mass of the dispersion.

5. The method for preparing a novel silicon micropowder / MOFs composite material according to claim 1, characterized in that: In step 1, the polymer is polyacrylonitrile PAN or polyvinyl alcohol PVA.

6. The method for preparing a novel silicon micropowder / MOFs composite material according to claim 1, characterized in that: In step 2, the spinning parameters set by the electrospinning equipment include a voltage of 15 to 25 kV, a receiving distance of 10 to 20 cm, and a propulsion speed of 0.5 to 2 mL / h.

7. The method for preparing a novel silicon micropowder / MOFs composite material according to claim 1, characterized in that: In step 3, the heat treatment process is:

1. Put the prepared composite fiber membrane into an oven; 2. Set the oven temperature to 100°C and the heat treatment time to 1.5 hours; 3. After the heat treatment, take out the fiber membrane and cool it to room temperature.

8. The method for preparing a novel silicon micropowder / MOFs composite material according to claim 1, characterized in that: In step 3, the chemical cross-linking process is: Prepare cross-linking solution: mix glutaraldehyde solution with ethanol, wherein the purity of ethanol is ≥95%, stir evenly, the volume of glutaraldehyde: volume of ethanol = 5:95; A small amount of catalyst is added to obtain a glutaraldehyde cross-linking solution to accelerate the cross-linking reaction; The catalyst accounts for 0.5% of the cross-linking solution by mass; Cross-linking treatment: immerse the composite fiber membrane in the prepared glutaraldehyde cross-linking solution to ensure that the composite fiber membrane is completely immersed; 20 mL of glutaraldehyde cross-linking solution was used per gram of composite fiber membrane; Crosslink at room temperature to 40°C for 1.5 hours; Cleaning and drying: After cross-linking, take out the composite fiber membrane and wash it several times with deionized water or ethanol to remove unreacted glutaraldehyde and catalyst; The fiber membrane is dried at room temperature or in an oven.

9. The method for preparing a novel silicon micropowder / MOFs composite material according to claim 8, characterized in that: The catalyst used in the chemical cross-linking process is hydrochloric acid, and the concentration of the hydrochloric acid is 0.5%.

10. Application of the composite fiber membrane obtained by the preparation method of a novel silicon micropowder / MOFs composite material according to claims 1-9 in the field of water treatment.