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CN-122006499-A - Composite nanofiber filter material for cooperatively removing particulate matters and sulfur dioxide and preparation method thereof

CN122006499ACN 122006499 ACN122006499 ACN 122006499ACN-122006499-A

Abstract

The invention discloses a composite nanofiber filter material for cooperatively removing particulate matters and sulfur dioxide and a preparation method thereof, and belongs to the technical field of flue gas purifying filter materials. According to the invention, an electrostatic spinning Polyimide (PI) nanofiber is used as a substrate, and amine functionalized UiO-66-NH 2 crystals are grown on the surface of the fiber in situ, so that a PI@UiO-66-NH 2 composite fiber membrane with a core-shell structure is constructed. The filter material has excellent back blowing regeneration performance by relying on a surface filtering mechanism of the electrostatic spinning nanofiber, and the UiO-66-NH 2 shell layer can provide rich Zr-OH defect sites and alkaline amino (NH 2 ) active sites, SO that the targeted adsorption and selective removal capacity of sulfur dioxide (SO 2 ) is remarkably improved. The composite fiber filter material prepared by the invention effectively solves the problems that the traditional fiber filter material is difficult to back-blow and regenerate, has single function, is difficult to cooperatively remove particulate matters and SO 2 , and the like, and can be widely applied to the fields of industrial high-temperature flue gas filtration and waste gas deep purification.

Inventors

  • ZHONG LUBIN
  • ZENG QINGHAO
  • ZHENG YUMING

Assignees

  • 中国科学院城市环境研究所

Dates

Publication Date
20260512
Application Date
20260414

Claims (8)

  1. 1. A preparation method of a composite nanofiber filter material for cooperatively removing particles and sulfur dioxide is characterized by comprising the following steps of 1, dissolving an aromatic dianhydride monomer and an aromatic diamine monomer in an organic solvent for polymerization reaction to prepare a polyamic acid spinning solution, 2, carrying out electrostatic spinning on the polyamic acid spinning solution to obtain a polyamic acid nanofiber membrane, 3, carrying out thermal imidization treatment on the polyamic acid nanofiber membrane in an inert atmosphere to obtain a polyimide nanofiber substrate, and 4, immersing the polyimide nanofiber substrate in a mixed solution containing a zirconium source, an amino phthalic ligand and a regulator for in-situ growth reaction, and washing and drying after the reaction is finished to obtain the composite nanofiber filter material with the surface loaded with an amino metal organic frame material.
  2. 2. The method according to claim 1, wherein in the step 1, the aromatic dianhydride monomer is 3,3', 4' -biphenyl tetracarboxylic dianhydride, the aromatic diamine monomer is 4,4' -diaminodiphenyl ether, the organic solvent is N, N-dimethylformamide, in the step 3, the inert atmosphere is nitrogen atmosphere, and in the step 4, the metal amide organic framework material is UIO-66-NH 2 .
  3. 3. The preparation method of the zirconium oxide film according to claim 2, wherein in the step 4, the zirconium source is zirconium chloride, the amino phthalic acid ligand is 2-amino terephthalic acid, the regulator is benzoic acid, the molar ratio of the zirconium chloride, the 2-amino terephthalic acid and the benzoic acid is 1 (0.8-1.2): 15-25), and the in-situ growth reaction temperature is 100-150 ℃ for 2-12 hours.
  4. 4. The method of claim 1, wherein in step 2, the parameters of the electrostatic spinning process are controlled so that the fiber diameter of the polyimide nanofiber substrate obtained after the transformation of the polyamide acid nanofiber membrane in step 3 is 100-400 nm and the membrane thickness is 10-50 μm.
  5. 5. A composite nanofiber filter material for cooperatively removing particles and sulfur dioxide is characterized by comprising a polyimide nanofiber inner core and an amino metal organic framework shell loaded on the surface of the inner core to form a core-shell structure, wherein the fiber diameter of the polyimide nanofiber inner core is 100-400 nm, the thickness of the amino metal organic framework shell is 50-100 nm, and the shell material is UiO-66-NH 2 crystals.
  6. 6. The composite nanofiber filter according to claim 5, wherein the filter has a filtration efficiency of not less than 99.5% on particulate matter and a pressure drop at a filtration wind speed of not more than 200 Pa, and/or a dynamic saturation adsorption capacity of not less than 30 mg g -1 at a concentration of 500: 500 ppm SO 2 at 25 ℃.
  7. 7. The composite nanofiber filter medium according to claim 5, wherein the dynamic adsorption capacity retention rate of SO 2 is not less than 85% after at least 5 adsorption-desorption cycles, and/or the adsorption capacity of SO 2 is maintained at more than 60% of the initial adsorption capacity at 25 ℃ within a temperature range of 55-85 ℃.
  8. 8. The composite nanofiber filter according to claim 5, wherein the pressure drop increase of the filter after ten water washing cycles is less than 15% of the initial pressure drop, and the total filtration time is >8000 seconds.

Description

Composite nanofiber filter material for cooperatively removing particulate matters and sulfur dioxide and preparation method thereof Technical Field The invention belongs to the technical field of filter materials, and particularly relates to a composite nanofiber filter material for cooperatively removing particulate matters and sulfur dioxide and a preparation method thereof. Background Rapid urban and industrial expansion exacerbates global air pollution, wherein flue gas discharged from high-temperature processes such as coal-fired power plants is a main pollution source and often contains a mixture of fine particulate matters (PM 2.5) and sulfur dioxide (SO 2). PM 2.5 can go deep into the lungs to cause disease and SO 2 can harm health and cause acid rain. The semi-dry desulfurization is commonly used for small and medium boilers due to low cost and low water consumption, but the SO 2 removal rate is only 70-90%, and 150-450 ppm SO 2 (about 80 ℃) remains in the treated flue gas. Although the bag filter can collect particles, the filtering efficiency is limited and the filter bag is easy to be blocked. Therefore, how to deeply and cooperatively purify SO 2 and PM is still a technical problem, and the research on advanced materials is promoted. The electrospun nanofiber becomes a high-efficiency filter medium due to high specific surface area and high porosity, and micropores of the electrospun nanofiber can realize surface filtration, so that the electrospun nanofiber is convenient for back blowing regeneration. However, the industrial flue gas temperature is high, and the thermal stability of the material is strictly required. In the existing high-temperature resistant fiber materials, inorganic fiber materials (such as alumina) are heat-resistant but brittle, and organic high-temperature resistant fiber materials such as common commercial PTFE coating filter materials have the problems of higher filtration resistance, poor back blowing regeneration capacity and the like. Polyimide (PI) has excellent mechanical strength, chemical stability and heat resistance thanks to the rigid aromatic skeleton and the heterocyclic imide unit, so that the Polyimide (PI) is an ideal material for filtering application under the condition of severe high-temperature flue gas. Studies show that the removal rate of PM2.5 by PI nano-fiber in a wider temperature range (such as 25-370 ℃) exceeds 99.5%, and the filtration efficiency of PM0.3 even after 390 ℃ treatment still reaches 99.96%. Despite these advantages, polyimide-based filters are primarily designed for particulate removal, often lacking the function of simultaneously capturing sulfur dioxide, which limits their use in integrated flue gas cleaning systems. Porous materials such as activated carbon, zeolites have limited adsorption selectivity or capacity in terms of SO 2 removal. Metal Organic Frameworks (MOFs) have significant advantages in low concentration SO 2 capture due to their pore channel tunability and chemical tunability. Among them, zirconium-based MOFs such as UiO-66 are recognized as one of the most practical adsorbents due to their excellent thermal stability and excellent chemical mechanical properties. The zirconium-based MOF (such as UiO-66) has high thermal stability (structural integrity can be maintained at a temperature of up to about 500 ℃), ordered structure and easy functionalization, has an easy-to-obtain precursor and a mature scale synthesis route, and is a promising candidate material for deeply removing low-concentration SO 2 in high-temperature industrial flue gas. In this study, a bifunctional membrane was designed by combining heat resistant PI nanofibers with UiO-66-NH 2 for simultaneous removal of PM and SO 2 at high temperature. PI nanofibers are selected as fiber scaffolds that are able to withstand solvothermal conditions required for UiO-66 in situ growth due to their excellent thermal and mechanical stability. In addition, the high specific surface area, high porosity and interconnected pore network of the nanofiber matrix create a three-dimensional gas permeation pathway that facilitates mass transport during SO 2 adsorption. To further enhance affinity to acidic SO 2 molecules, the functionalization of UiO-66 by ligand modification, the introduction of electron donor-amino groups, thereby creating basic adsorption sites, it is expected that targeted SO 2 binding can be enhanced by acid-base interactions. In addition, MOF-derived nanotextured surfaces increase fiber surface roughness, which can enhance particle adhesion and inhibit particle secondary escape during filtration. The system evaluated the performance of the membrane in terms of particle filtration and SO 2 adsorption under conditions associated with industrial flue gas treatment, including high temperatures and repeated adsorption-regeneration cycles, to evaluate its suitability in complex operating environments. The research provides a mechanistic insight for de