Search

CN-121988304-A - Bionic porous wood-based BNNS-MOF composite adsorbent and preparation process and application thereof

CN121988304ACN 121988304 ACN121988304 ACN 121988304ACN-121988304-A

Abstract

The invention relates to the technical field of gas adsorption materials, in particular to a bionic porous wood-based BNNS-MOF composite adsorbent and a preparation process and application thereof. The invention takes natural wood sponge as a three-dimensional substrate, the through pore canal of the natural wood sponge not only provides a rapid diffusion path for toluene molecules, but also provides a supporting foundation for anchoring a subsequent functional layer by virtue of rich hydroxyl active sites, BNNS is taken as an intermediate modification layer, the integral moisture resistance of the material is improved by virtue of the high thermal conductivity and hydrophobic property of the BNNS, the affinity and capture capacity of the para-toluene molecules are obviously enhanced by regulating and controlling the electronic structure and coordination environment of ZIF-67 through iron ion doping, the efficient recognition and selective adsorption of the para-toluene molecules are realized, and the Fe-doped ZIF-67 is firmly anchored on a wood sponge skeleton through BNNS, so that a 'conductive-hydrophobic-adsorption' ternary synergistic system is formed, and new materials and new paths are provided for efficient removal of volatile organic matters in a high-humidity environment.

Inventors

  • DING BAISUO
  • WANG QIANYOU
  • LIU HUALI
  • LIU KANG

Assignees

  • 理工清科(重庆)先进材料研究院有限公司

Dates

Publication Date
20260508
Application Date
20260302

Claims (10)

  1. 1. The preparation process of the bionic porous wood-based BNNS-MOF composite adsorbent is characterized by comprising the following steps of: Adding cobalt nitrate hexahydrate and ferric nitrate hexahydrate into absolute methanol, stirring and dissolving to obtain a metal salt solution; Immersing BNNS/wood sponge into metal salt solution completely, immersing for 30-40 min under the pressure of-0.1 MPa, immersing for 1-2 h under the atmospheric pressure, taking out BNNS/wood sponge adsorbed with Co 2+ and Fe 3+ , immersing in ligand solution, standing at room temperature for reaction for 24-48 h, taking out the reacted composite material, putting into methanol for ultrasonic treatment for 20-30 s, taking out massive solid, immersing for 1-2 h again with methanol, taking out, and freeze-drying for 24-36 h at the temperature of-50 to-30 ℃ to obtain the bionic porous wood-based BNNS-MOF composite adsorbent; The BNNS/wood sponge is a compound of activated boron nitride nano-sheets and wood sponge.
  2. 2. The preparation method according to claim 1, wherein the molar ratio of cobalt nitrate hexahydrate to iron nitrate hexahydrate is (4-7): 1.
  3. 3. The preparation method according to claim 2, wherein the molar ratio of the total molar amount of cobalt nitrate hexahydrate and iron nitrate hexahydrate to dimethylimidazole is 1 (8-15).
  4. 4. The preparation method according to claim 1, wherein the preparation method of the BNNS/wood sponge comprises the following steps: Adding the activated boron nitride nanosheets into methanol, stirring and dispersing to obtain BNNS methanol dispersion liquid with the mass concentration of 20-50%; and (3) in a container, fully soaking the wood sponge in BNNS methanol dispersion liquid, then placing the container in a vacuum drying oven, vacuumizing and maintaining the pressure of-0.1 MPa for 30-40 min, observing until no bubbles are generated from the wood, releasing the vacuum, continuously soaking for 4-5 h under the atmospheric pressure, taking out the wood sponge, washing with anhydrous methanol, and then freeze-drying at-50 ℃ for 18-24 h to obtain the BNNS/wood sponge.
  5. 5. The method of claim 4, wherein the activated boron nitride nanoplatelets are prepared by: Adding hexagonal boron nitride powder into isopropanol water solution, carrying out ultrasonic treatment for 4-6 hours under the ice bath condition and using an ultrasonic breaker to obtain suspension, centrifuging the suspension at 8000-10000 rpm for 20-30 min, absorbing supernatant to obtain BNNS dispersion, mixing the BNNS dispersion with 3mol/L nitric acid solution, reacting for 6-8 hours at 120-150 ℃, naturally cooling, pouring the obtained reactant into deionized water for dilution, carrying out suction filtration until filtrate is neutral, and carrying out vacuum drying on solid obtained by suction filtration to obtain the activated boron nitride nanosheets.
  6. 6. The method according to claim 4, wherein the wood sponge is prepared by the following steps: Cutting balsawood into blocks, adding a mixed aqueous solution containing NaOH and Na 2 SO 3 , and heating at 95-100 ℃ for 12-15 hours to obtain delignified wood; And (3) washing the wood subjected to delignification by deionized water, soaking in a NaOH solution, soaking at 80-90 ℃ for 8-10 hours, taking out the wood, washing by deionized water, then placing in a freeze dryer, freeze-drying at-50 ℃ for 3-4 hours, and freeze-drying at 10Pa for 24-36 hours to obtain the white wood sponge.
  7. 7. The method according to claim 6, wherein the concentration of NaOH in the aqueous mixture is 2.0-2.5 mol/L and the concentration of Na 2 SO 3 is 0.3-0.6 mol/L.
  8. 8. The method according to claim 6, wherein the concentration of the NaOH solution is 8 to 10wt%.
  9. 9. The bionic porous wood-based BNNS-MOF composite adsorbent prepared by the preparation method according to any one of claims 1-8.
  10. 10. The use of the biomimetic porous wood-based BNNS-MOF composite adsorbent according to claim 9 in toluene adsorbent materials.

Description

Bionic porous wood-based BNNS-MOF composite adsorbent and preparation process and application thereof Technical Field The invention relates to the technical field of gas adsorption materials, in particular to a bionic porous wood-based BNNS-MOF composite adsorbent and a preparation process and application thereof. Background The treatment of Volatile Organic Compounds (VOCs) is one of the key links in the prevention and treatment of atmospheric pollution. The substances have toxicity, carcinogenicity or environmental hormone interference effect, can generate chain photochemical reaction with nitrogen oxides under illumination conditions, generate secondary pollutants such as ozone, formaldehyde and the like, promote the formation of fine particles, and form double threats to regional air quality and public health. Toluene is a typical representative of aromatic VOCs, and is an important component in stationary source and mobile source emissions due to its wide use in industrial solvents and synthetic raw materials. The steam is easy to be absorbed by respiratory tract, and can cause accumulated damage to central nervous system and hematopoietic system after long-term contact, and at the same time, benzene ring contained in molecular structure makes it a key reactant for photochemical smog generation. Along with the increasingly strict emission standards of various countries, especially the continuous tightening of emission limit values under the working conditions of low concentration and high humidity, the development of adsorption materials which can realize deep purification, have strong anti-interference performance and stable operation has become an urgent requirement of industry. At present, the industrial adsorption technology mainly depends on two materials, namely active carbon and molecular sieve, but the active carbon and the molecular sieve have obvious limitations in application. The activated carbon realizes physical adsorption by depending on a developed pore structure, the specific surface area is high, but the surface chemical property lacks directional regulation and control capability, so that the selective adsorption capability of the p-toluene is limited, and the pores are easy to be preempted by water molecules in a humid environment, so that the adsorption efficiency is suddenly reduced. Some researches try to improve the hydrophobicity through chemical modification, such as introducing fluorine-containing groups, but possibly bring secondary pollution risks, and do not accord with the principle of green development. Although the molecular sieve material has regular pore channels and polar surfaces, the adsorption of the para-toluene is mainly carried out by Van der Waals force, the binding force is weak, desorption easily occurs under the condition of temperature fluctuation or air flow impact, and the stable long-acting interception of pollutants is difficult to realize. The metal organic framework material is used as an emerging porous material, and has great potential in the field of gas adsorption separation by virtue of the advantages of adjustable structure, large specific surface area and the like. The pi-pi accumulation or acid-base action site capable of specifically recognizing toluene is constructed through ligand functionalization or metal node modification, so that the adsorption selectivity and capacity are remarkably improved. However, the water stability of most MOF materials is still a bottleneck limiting their practical application-liquid or saturated water often results in hydrolysis of metal-ligand bonds in their framework structure, leading to pore collapse and activity failure. Disclosure of Invention In view of the above, the invention aims to provide the bionic porous wood-based BNNS-MOF composite adsorbent, and the preparation process and application thereof, so that the synchronous improvement of the toluene adsorption capacity, the speed and the moisture resistance is realized, and a new material is provided for the efficient removal of volatile organic compounds in a high-humidity environment. The invention solves the technical problems by the following technical means: In a first aspect, an embodiment of the present invention provides a preparation process of a bionic porous wood-based BNNS-MOF composite adsorbent, including the following steps: Adding cobalt nitrate hexahydrate and ferric nitrate hexahydrate into absolute methanol, stirring and dissolving to obtain a metal salt solution; Immersing BNNS/wood sponge into metal salt solution completely, immersing for 30-40 min under the pressure of-0.1 MPa, immersing for 1-2 h under the atmospheric pressure, taking out BNNS/wood sponge adsorbed with Co 2+ and Fe 3+, immersing in ligand solution, standing at room temperature for reaction for 24-48 h, taking out the reacted composite material, putting into methanol for ultrasonic treatment for 20-30 s, taking out massive solid, immersing for 1-2 h again with