Balsa wood MOF composite material for gaseous formaldehyde adsorption and preparation method and application of balsa wood MOF composite material

Abstract

The invention relates to the technical field of formaldehyde adsorbents, and particularly discloses a cork wood MOF composite material for gaseous formaldehyde adsorption and a preparation method and application of the cork wood MOF composite material. The preparation method of the composite material comprises the following steps: S1, carrying out steam explosion pretreatment on the light wood blocks; s2, carrying out high-temperature carbonization treatment on the light wood blocks after steam explosion; s3, UiO-66-NH2 and carbonized light wood blocks are compounded, transverse gap structures in the light wood are communicated through green and simple steam explosion pretreatment, the void ratio of the light wood is further increased through high-temperature carbonization, a multi-stage gap structure is regulated and controlled, UiO-66-NH2 particles are combined with internal pore channels of the light wood through a hydrothermal synthesis method, and the light wood is obtained. The adsorption advantages of the two composite components of the balsa wood and the MOF are fully exerted, and the balsa wood / MOF composite adsorption material with a large number of adsorption sites is prepared and has relatively high adsorption efficiency on gaseous formaldehyde.

Description

Technical Field

[0001] The invention belongs to the technical field of formaldehyde adsorbents, and specifically relates to a balsa wood MOF composite material for gaseous formaldehyde adsorption, and a preparation method and application thereof. Background Art

[0002] With the rapid development of industrialization and informatization, people now spend about 80-90% of their time indoors. Indoor air pollution is a worldwide concern and is recognized as one of the killers of human health. Formaldehyde is one of the most common volatile organic compounds in indoor environments. It mainly comes from furniture, floors, wall panels, ceilings made of "trialdehyde" resins, and other indoor decorative materials such as carpets, wallpapers, and paints. People who are exposed to excessive formaldehyde for a long time are prone to throat and nasal pain, headaches, nausea, coughs, and breathing problems. More serious ones may cause liver and kidney failure, chromosome mutations, leukemia, and cancer. The World Health Organization and the International Agency for Research on Cancer define it as a Class I carcinogen and teratogen. Therefore, it is of great practical significance to develop materials for removing formaldehyde gas from indoor air. Metal organic frameworks (MOFs) are an emerging porous material with the advantages of high porosity, low density, large specific surface area, and diverse topological structures. MOFs are constructed by organic ligands and inorganic metal centers through coordination bonds. Among them, UiO-66 is a typical zirconium-based metal organic framework, which is formed by coordination between zirconium ions (Zr) and organic ligands such as terephthalic acid. The UIO-66 structure has a porous crystal structure in which organic ligands and metal ions are arranged alternately to form pores and channels. However, due to the inherent crystalline properties of MOFs, their morphology also limits their further processing and practical applications. Therefore, it is necessary to combine MOFs with a matrix with good structural stability to synthesize new functional composite materials. At the same time, by introducing amino (-NH2) groups on its ligands to become UiO-66-NH2, the structural flexibility and chemical adsorption sites of MOFs can be further improved.

[0003] Wood is a naturally porous material with a rich pore structure. The main chemical components of wood, hemicellulose and cellulose molecules, contain carboxyl (-COOH) groups and hydroxyl (-OH) groups, which can effectively promote the combination of MOFs and wood. Among them, balsa wood is the lightest wood in the world, with a density of only 0.2g / cm 3, with a developed multi-level void structure, and has a natural physical adsorption effect. Common processes in the prior art, such as the technical solution disclosed in the invention patent application with publication number CN115007117A, called "A wood aerogel and its preparation method and application": dehydrating the wood block, then soaking it in a mixed solution of sodium hydroxide and sodium sulfite to remove lignin, and obtaining the wood aerogel after drying, and then depositing the MOFs layer in the wood aerogel through an in-situ growth method to obtain the wood aerogel. The chemical method used in the above process to remove lignin has the problems of complex process and environmental pollution, and can only remove lignin in the wood. For adsorption, it will affect the adsorption effect of both lignin and hemicellulose, and affect the later loading effect and the adsorption effect of the composite. Summary of the invention

[0004] The purpose of the present invention is to address the above-mentioned deficiencies in the prior art and provide a balsa wood MOF composite material for gaseous formaldehyde adsorption and a preparation method and application thereof, connect the lateral void structure inside the balsa wood through green and simple steam explosion pretreatment, further improve the balsa wood porosity and regulate the multi-level void structure through high-temperature carbonization, combine UiO-66-NH2 particles with the internal pores of the balsa wood through a hydrothermal synthesis method, give full play to the adsorption advantages of the two composite components of balsa wood and MOF, and prepare a balsa wood / MOF composite adsorption material with a large number of adsorption sites, which has a relatively high adsorption efficiency for gaseous formaldehyde.

[0005] To achieve the above object, the present invention adopts the following technical solution: The first object of the present invention is to provide a method for preparing a balsa wood MOF composite material for gaseous formaldehyde adsorption, comprising the following steps: S1, steam explosion pretreatment of balsa wood blocks; S2, high temperature carbonization treatment of balsa wood blocks after steam explosion; S3, UiO-66-NH2 and carbonized balsa wood block are composited, and the specific process is: zirconium chloride and 2-aminoterephthalic acid are mixed in a molar ratio of 3:7~7:3 in N, N-dimethylformamide and acetic acid with a molar ratio of 12:1, and the carbonized balsa wood block obtained in step S2 is added, and the mass ratio of UiO-66-NH2 to the carbonized balsa wood block is 1%~5%, and the mixed solution is stirred evenly, and then the mixed solution is heated, cooled to room temperature after the reaction is completed, and the precipitate is collected by filtration, and the balsa wood MOF composite material is obtained after washing and drying.

[0006] Furthermore, in step S1, the steam explosion pretreatment is performed at a pressure of 0.8-1.5 MPa and a pressure holding time of 60-180 s.

[0007] Furthermore, in step S1, the steam explosion pretreatment is performed at a pressure of 1.5 MPa and a holding time of 60 seconds.

[0008] Furthermore, in step S2, the carbonization treatment is performed by placing the mixture in a tubular furnace under the protection of a protective gas at a heating rate of 2-10°C / min, heating the mixture to 500-1000°C, and carbonizing the mixture for 2-6 hours.

[0009] Furthermore, in step S2, the carbonization treatment is performed by placing the mixture in a tubular furnace under the protection of a protective gas at a heating rate of 2-10°C / min, heating the mixture to 800°C, and carbonizing the mixture for 2-6 hours.

[0010] Furthermore, in step S3, the molar ratio of zirconium chloride to 2-aminoterephthalic acid is 3:7 to 7:3.

[0011] Furthermore, the size of the balsa wood block is 0.5-2 cm in length, 0.5-2 cm in width, and 1-2 cm in height.

[0012] The second object of the present invention is to provide a balsa wood MOF composite material prepared by the above-mentioned preparation method.

[0013] The third object of the present invention is to provide the use of the above-mentioned balsa wood MOF composite material in the preparation of adsorbent products.

[0014] The fourth object of the present invention is to provide a formaldehyde adsorbent, comprising the above-mentioned balsa wood MOF composite material.

[0015] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects: The present invention uses balsa wood with a porous structure that has not been subjected to any modification treatment and has a good formaldehyde adsorption effect after carbonization. The adsorption effect of unloaded carbonized balsa wood is 10-45 times that of unloaded and uncarbonized balsa wood of the same shape. At the same time, the balsa wood after steam explosion has a larger specific surface area and a laterally connected pore structure, which is conducive to the uniform dispersion of UiO-66-NH2 during hydrothermal synthesis and effective entry into the internal pores of the balsa wood block to increase the MOF loading amount. The preparation method of balsa wood / MOF composite adsorption material has the advantages of simple process, easy control, green environmental protection and relatively low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a cross-section of unsteam-exploded balsa wood; Figure 2 A cross-section of balsa wood after steam explosion and carbonization. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical scheme and advantages of the present invention clearer, the specific embodiments of the present invention are further described in detail below in conjunction with specific examples. If no specific technology or conditions are specified in the examples, the technology or conditions described in the literature in this field or the product instructions are used. If the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be obtained commercially.

[0018] Example 1 This embodiment provides a method for preparing a balsa wood MOF composite material for gaseous formaldehyde adsorption, which specifically comprises the following steps: Step S1, taking an air-dried balsa wood block with a size of 0.5-2 cm, a width of 0.5-2 cm, and a height of 1-2 cm, soaking it in water for 12-48 hours, and using steam explosion pretreatment at a pressure of 0.8 MPa and a holding time of 60 seconds to remove part of the hemicellulose and lignin in the balsa wood block, and open up the balsa wood transverse channel; Step S2, the balsa wood block after steam explosion is subjected to high temperature carbonization treatment, and is placed in a tubular furnace under the protection of protective gas at a heating rate of 2-10°C / min, and the temperature is raised to 400°C for a carbonization time of 2-6h; Step S3: zirconium chloride (ZrCl4) and 2-aminoterephthalic acid (C8H7NO4) are mixed in a molar ratio of 5:5 in N, N-dimethylformamide (DMF) and acetic acid (CH3COOH) with a molar ratio of 12:1 to obtain UiO-66-NH2, and the carbonized balsa wood block obtained in step S2 is added, and the mass ratio of UiO-66-NH2 to the carbonized balsa wood block is 1% to 5%. Stir well until a uniform and transparent solution is obtained, and then the mixed solution is heated to 120 °C for 24 hours and then cooled to room temperature. The precipitate is filtered and repeatedly washed with DMF and methanol and then dried in vacuum at 80 °C.

[0019] Example 2 This embodiment provides a method for preparing a balsa wood MOF composite material for gaseous formaldehyde adsorption, which is basically the same as Example 1, except that the steam explosion time is 180 seconds.

[0020] Example 3 This embodiment provides a method for preparing a balsa wood MOF composite material for gaseous formaldehyde adsorption, which is basically the same as Example 1, except that the steam explosion time is 180s and the carbonization temperature is 600°C.

[0021] Example 4 This embodiment provides a method for preparing a balsa wood MOF composite material for gaseous formaldehyde adsorption, which is basically the same as Example 1, except that the steam explosion pressure is 1.5 MPa and the carbonization temperature is 600°C.

[0022] Example 5 This embodiment provides a method for preparing a balsa wood MOF composite material for gaseous formaldehyde adsorption, which is basically the same as Example 1, except that the steam explosion time is 180 s, the steam explosion pressure is 1.5 MPa, and the carbonization temperature is 600°C.

[0023] Example 6 This embodiment provides a method for preparing a balsa wood MOF composite material for gaseous formaldehyde adsorption, which is basically the same as Example 1, except that the steam explosion time is 60 seconds, the steam explosion pressure is 1.5 MPa, and the carbonization temperature is 600°C.

[0024] Example 7 This embodiment provides a method for preparing a balsa wood MOF composite material for gaseous formaldehyde adsorption, which is basically the same as that of embodiment 1, except that the steam explosion pressure is 1.5 MPa and the carbonization temperature is 1000°C.

[0025] Example 8 This embodiment provides a method for preparing a balsa wood MOF composite material for gaseous formaldehyde adsorption, which is basically the same as Example 1, except that the steam explosion pressure is 1.5 MPa, the carbonization temperature is 800°C, and the molar ratio of zirconium chloride to 2-aminoterephthalic acid is 3:7.

[0026] Example 9 This embodiment provides a method for preparing a balsa wood MOF composite material for gaseous formaldehyde adsorption, which is basically the same as Example 1, except that the steam explosion pressure is 1.5 MPa, the carbonization temperature is 800°C, and the molar ratio of zirconium chloride to 2-aminoterephthalic acid is 7:3.

[0027] Comparative Example 1 Untreated balsa wood blocks.

[0028] The experimental process of formaldehyde adsorption is as follows: Adjust the main flow meter to 200m 3 / h, measure a set of data at intervals of 10 minutes. Each time, ventilate the gas collecting bottle to be tested for 60 seconds, dilute it to a 100ml volumetric flask, transfer 2ml to a colorimetric tube with a pipette, dilute the colorimetric tube to 10ml with distilled water, add 2ml of color developer and shake well, heat for 10 minutes, protect from light for 1h, and then measure its absorbance.

[0029] The pressure of the gas cylinder was adjusted to 0.06Mpa, the first water bath was filled with formaldehyde and anhydrous calcium chloride at 30°C, the second water bath was filled with samples at 25°C, and the UV spectrophotometer was adjusted to 412nm.

[0030] Prepare 500ml of color developer (acetic acid acetone solution): acetic acid acetone 1ml, glacial acetic acid 1.5ml, ammonium acetate 75g; dissolve ammonium acetate in about 400ml of distilled water, then add acetic acid acetone and glacial acetic acid and stir. Transfer to a 500ml volumetric flask, make up to volume, turn over to make it uniform, and store away from light.

[0031] Table 1. Comparison of adsorption effects of different implementation groups

[0032] In the absence of conflict, the above embodiments and features in the embodiments may be combined with each other.

[0033] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a balsa wood MOF composite material for gaseous formaldehyde adsorption, characterized in that: The following steps are involved: S1, steam explosion pretreatment of balsa wood blocks; S2, high temperature carbonization treatment of balsa wood blocks after steam explosion; S3, UiO-66-NH2 and carbonized balsa wood block are composited, and the specific process is: zirconium chloride and 2-aminoterephthalic acid are mixed in a molar ratio of 3:7~7:3 in N, N-dimethylformamide and acetic acid with a molar ratio of 12:1, and the carbonized balsa wood block obtained in step S2 is added, and the mass ratio of UiO-66-NH2 to the carbonized balsa wood block is 1%~5%, and the mixed solution is stirred evenly, and then the mixed solution is heated, cooled to room temperature after the reaction is completed, and the precipitate is filtered and collected, and the balsa wood MOF composite material is obtained after washing and drying.

2. The preparation method according to claim 1, characterized in that In step S1, the steam explosion pretreatment is performed at a pressure of 0.8-1.5 MPa and a pressure holding time of 60-180 s.

3. The preparation method according to claim 1, characterized in that: In step S1, the pressure of the steam explosion pretreatment is 1.5 MPa, and the pressure holding time is 60 s.

4. The preparation method according to claim 2, characterized in that: In step S2, the carbonization treatment is to place the mixture in a tubular furnace under the protection of a protective gas at a heating rate of 2-10°C / min, raise the temperature to 500-1000°C, and the carbonization time is 2-6h.

5. The preparation method according to claim 3, characterized in that: In step S2, the carbonization treatment is to place the material in a tubular furnace under the protection of a protective gas at a heating rate of 2-10°C / min, raise the temperature to 800°C, and the carbonization time is 2-6h.

6. The preparation method according to claim 1, characterized in that: In step S3, the molar ratio of zirconium chloride to 2-aminoterephthalic acid is 3:7 to 7:

3.

7. The preparation method according to claim 1, characterized in that: The size of the balsa wood block is 0.5-2 cm in length, 0.5-2 cm in width, and 1-2 cm in height.

8. A balsa wood MOF composite material, characterized in that: The preparation is obtained by the preparation method as described in claims 1-7.

9. Use of the balsa wood MOF composite material as claimed in claim 8 in the preparation of an adsorbent product.

10. A formaldehyde adsorbent, characterized in that: The method comprises the balsa wood MOF composite material as claimed in claim 8.

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