A modified hydrophobic chestnut shell fiber aerogel loaded with diamine-modified magnesium-based MOF and its preparation method and application

Abstract

The present invention application discloses a modified hydrophobic chestnut shell fiber aerogel loaded with diamine-modified magnesium-based MOF and its preparation and application. The modified hydrophobic chestnut shell fiber aerogel loaded with diamine-modified magnesium-based MOF described in the present invention application presents a lamellar structure, which is convenient for the adsorption of formaldehyde. At the same time, by modifying the MOF with diamines, the formaldehyde removal effect in a high humidity environment is greatly improved. The present invention application forms hydrogen bond crosslinks with the carboxyl groups of the chestnut shell fibers through the abundant groups on the surface of the diamine-modified magnesium-based MOF, and self-assembles to form a layered porous structure aerogel without adding an additional crosslinking agent. The abundant pores and amino groups contribute to the adsorption of formaldehyde. At the same time, the hydrophobic modification of the diamine group improves the formaldehyde removal effect of the material in a high humidity environment, and has more practical application prospects.

Description

Technical Field

[0001] The present invention belongs to the field of formaldehyde removal and relates to a modified hydrophobic chestnut shell fiber aerogel loaded with diamine-modified magnesium-based MOF, and a preparation method and application thereof. Background Art

[0002] With the widespread use of interior decoration materials, formaldehyde, as a major volatile organic pollutant, poses a serious threat to human health due to its strong carcinogenicity and long-term release characteristics. Currently, common formaldehyde treatment technologies such as activated carbon adsorption and photocatalytic degradation have significant limitations: activated carbon has a limited adsorption capacity and is easily saturated, making it difficult to regenerate; photocatalytic materials rely on ultraviolet light, which limits their practical application; and most metal-organic framework (MOF) materials, although they have a high specific surface area, are prone to structural collapse in hot and humid environments and have insufficient selective adsorption capacity for formaldehyde. In recent years, biomass-based aerogels have attracted attention due to their environmental friendliness, lightweight, and functionalization properties. However, the inherent hydrophilicity of natural fibers causes their adsorption performance to drop sharply in high humidity environments, limiting their practical application.

[0003] In existing technologies, magnesium-based MOFs (such as Mg-MOF-74) exhibit excellent adsorption potential for polar molecules due to their open metal sites, but unmodified MOFs have weak chemical binding ability for formaldehyde. Some studies have attempted to load MOFs onto porous supports to improve stability, but the choice of supports is generally limited to inorganic materials (such as silica) or synthetic polymers, which are costly and difficult to balance with biodegradability. In addition, traditional hydrophobic modification methods (such as fluorination) pose environmental pollution risks. While amine-functionalized MOFs can enhance formaldehyde capture through Schiff base reactions, single physical or chemical adsorption mechanisms make it difficult to achieve efficient and long-term purification. Summary of the Invention

[0004] In order to overcome the defects of the above-mentioned prior art, the present invention applies to form hydrogen bond cross-links between hydroxyl groups in chestnut shell fibers and diamine-modified Mg-MOF, and obtain hydrophobic modification through electrostatic attraction, and provides a modified hydrophobic chestnut shell fiber aerogel loaded with diamine-modified magnesium-based MOF, wherein the chestnut shell fibers and diamine-modified Mg-MOF self-assemble to form a lamellar aerogel, and the material presents a three-dimensional ordered arrangement, which is convenient for the adsorption of formaldehyde. At the same time, the positively charged hydrophobic long-chain macromolecules are combined with the negatively charged chestnut shell fibers to give the surface hydrophobic properties, thereby improving the formaldehyde removal effect in a high humidity environment.

[0005] This invention innovatively transforms agricultural waste chestnut shells into a three-dimensional fiber aerogel substrate, constructing a stable superhydrophobic surface through a green hydrophobic modification strategy that effectively resists humidity interference. Furthermore, a diamine-modified magnesium-based MOF is synthesized in situ within the aerogel framework. By leveraging the specific chemical interaction between amino groups and formaldehyde and the MOF's physical adsorption synergistic mechanism, the formaldehyde adsorption capacity and rate are significantly increased. This design not only achieves high-value utilization of biomass resources but also breaks through the performance bottleneck of traditional single materials through material cascade functionalization, providing an efficient, stable, and environmentally friendly solution for indoor formaldehyde pollution control.

[0006] The present invention application provides a modified hydrophobic chestnut shell fiber aerogel loaded with diamine-modified Mg-MOF (magnesium-based MOF). The modified hydrophobic chestnut shell fiber aerogel loaded with diamine-modified Mg-MOF is obtained by cross-linking chestnut shell fibers with diamine-modified Mg-MOF, and presents an ordered layered porous structure.

[0007] The present invention also provides a method for preparing a modified hydrophobic chestnut shell fiber aerogel loaded with diamine-modified Mg-MOF (magnesium-based MOF), the method comprising the following steps:

[0008] (1) Immerse chestnut shell powder in a solution consisting of ethanol and methanol, stir, and allow to stand at room temperature;

[0009] (2) washing with purified water, then filtering under reduced pressure to obtain the filter residue and drying it;

[0010] (3) Dissolve the metal salt in a DMF / H2O mixed solvent, then add the ligand and stir;

[0011] (4) heating the mixed solution after stirring in step (3) to obtain diamine-modified Mg-MOF, and then washing it with DMF / ethanol alternately and vacuum drying to obtain diamine-modified Mg-MOF powder;

[0012] (5) The filter residue obtained in step (2) and the diamine-modified Mg-MOF powder obtained in step (4) are dispersed in a 9M hydrochloric acid solution, ultrasonically mixed, LiF is added, stirred, filtered, and washed to obtain a hydrophobic chestnut shell fiber aerogel loaded with diamine-modified Mg-MOF;

[0013] (6) The hydrophobic chestnut shell fiber aerogel loaded with diamine-modified Mg-MOF is dispersed in pure water, ultrasonicated and modified by adding a modifier to obtain a modified hydrophobic chestnut shell fiber aerogel loaded with diamine-modified Mg-MOF.

[0014] In the step (1), the standing time is 1 hour to 48 hours; preferably, 24 hours.

[0015] In the step (1), the volume ratio of methanol to ethanol is 100-20:20; preferably, it is 80:20.

[0016] In the step (1), the mass / volume ratio of the chestnut shell powder to the solution consisting of methanol and ethanol is (1-10) g: (10-100) mL; preferably, 10 g: 100 mL.

[0017] In the step (2), the drying temperature is 25-70°C; preferably, 50°C.

[0018] In the step (3), the metal salt is selected from any one of Mg(NO3)2·6H2O, MgBr2, Mg(CH3COO)2·4H2O, MgCl2, etc.; preferably, it is Mg(NO3)2·6H2O.

[0019] In the step (3), the ligand is one or more of terephthalic acid, 2,5-dihydroxyterephthalic acid, etc.; preferably, it is 2,5-dihydroxyterephthalic acid.

[0020] In the step (3), the volume ratio of DMF to H2O in the DMF / H2O mixed solvent is 40:40-100; preferably, 40:60.

[0021] In the step (3), the concentration of the metal salt is 0.5-5 mol / L; preferably, 3.5 mol / L.

[0022] In the step (3), the mass ratio of the metal salt to the ligand is 1:1-1:20; preferably, it is 1:15.

[0023] In the step (4), the heating temperature is 120-200°C, preferably 120°C.

[0024] In step (4), the heating time is 6-24 hours; preferably, 12 hours.

[0025] In the step (4), the number of cleanings is 3 times.

[0026] In the step (4), the vacuum drying temperature is 25-70°C; preferably, 60°C.

[0027] In the step (4), the vacuum drying time is 6-24 hours; preferably, it is 6 hours.

[0028] In the step (5), the weight ratio of the filter residue to the diamine-modified Mg-MOF powder is 10:1-50:1; preferably, 10:1-30:1; further preferably, 15:1.

[0029] In the step (5), the mass ratio of the diamine-modified Mg-MOF to LiF is 1:1-1:10; preferably, it is 1:1.5.

[0030] In the step (5), the mass and volume ratio of the diamine-modified Mg-MOF to hydrochloric acid is 1 g:10 mL-1 g:50 mL; preferably, 1 g:30 mL.

[0031] In the step (5), the ultrasonic time is 0.5h-3h; preferably, 2h.

[0032] In the step (5), the stirring temperature is 20-50°C; preferably, 40°C.

[0033] In the step (5), the stirring time is 10 h to 30 h; preferably, 20 h to 30 h; more preferably, 24 h.

[0034] In the step (6), the mass ratio of the hydrophobic chestnut shell fiber aerogel loaded with diamine-modified Mg-MOF to pure water is (1-20): (1-100); preferably, it is 1:20.

[0035] In the step (6), the modifier is one of cetyltrimethylammonium bromide and cetyltrimethylammonium chloride, or a mixture thereof.

[0036] In the step (6), the mass ratio of the hydrophobic chestnut shell fiber aerogel loaded with diamine-modified Mg-MOF to the modifier is (1-2): (1-10); preferably, (1-1.5): (1-8); further preferably, 1:3.

[0037] In step (6), the ultrasonication time is 1 h to 4 h; preferably, 3.5 h.

[0038] In one embodiment, the method for preparing the modified hydrophobic chestnut shell fiber aerogel loaded with diamine-modified Mg-MOF described in the present application comprises the following steps:

[0039] (1) Dried chestnut shells were crushed to obtain chestnut shell powder. 10 g of the powder was immersed in 100 mL of a solution consisting of ethanol and methanol (80:20 v / v), stirred with a glass rod for better homogenization, and allowed to stand at room temperature for 24 h.

[0040] (2) Wash with pure water, then filter under reduced pressure to obtain the residue, and dry it in an oven at 50°C.

[0041] (3) Dissolve 3.5 mol / L Mg(NO3)2·6H2O in a DMF / H2O (40:60 v / v) mixed solvent, then add terephthalic acid with a mass ratio of ligand to Mg(NO3)2·6H2O of 1:15 and stir.

[0042] (4) The mixed solution treated in step (3) was poured into a polytetrafluoroethylene autoclave and heated at 120°C for 12 h to obtain diamine-modified Mg-MOF. The mixture was cooled to room temperature and then taken out, washed with DMF / ethanol alternately for 3 times, and vacuum-dried at 60°C for 6 h to obtain diamine-modified Mg-MOF powder.

[0043] (5) The filter residue from step (2) and the dried diamine-modified Mg-MOF powder were dispersed in a 9M hydrochloric acid solution, mixed uniformly by ultrasonication for 2 h, LiF was added, and stirred at 40°C for 24 h under a nitrogen atmosphere. The mixture was filtered and washed to obtain a chestnut shell fiber aerogel loaded with diamine-modified Mg-MOF cross-linked.

[0044] (6) Weigh the diamine-modified Mg-MOF cross-linked chestnut shell fiber aerogel, disperse it in pure water, and then slowly add the modifier. Ultrasonicate for 3.5 hours.

[0045] (7) Filter, wash with pure water and ethanol three times respectively, and freeze-dry to obtain the modified chestnut shell fiber aerogel loaded with diamine-modified Mg-MOF cross-linking.

[0046] The present application also provides a modified hydrophobic chestnut shell fiber aerogel loaded with diamine-modified Mg-MOF prepared by the above method.

[0047] The present application also provides the use of the modified hydrophobic chestnut shell fiber aerogel loaded with diamine-modified Mg-MOF in formaldehyde removal.

[0048] The beneficial effects of the present invention are as follows: the modified hydrophobic chestnut shell fiber aerogel loaded with diamine-modified magnesium-based MOFs described in the present invention exhibits a lamellar structure, which facilitates formaldehyde adsorption. Furthermore, the diamine modification of the MOF significantly improves formaldehyde removal efficiency in high-humidity environments, capable of removing 99% of formaldehyde within 24 hours. The present invention utilizes hydrogen bonding crosslinking between the abundant groups on the surface of the Mg-MOF and the hydroxyl groups of the chestnut shell fibers, allowing self-assembly to form a lamellar aerogel without the addition of an additional crosslinking agent. The abundant pores facilitate formaldehyde adsorption, and the hydrophobic modification enhances the material's formaldehyde removal efficiency in high-humidity environments, making it more promising for practical applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 SEM images of aerogels prepared in Examples 1-6 of the present invention;

[0050] Figure 2 N2 adsorption and desorption diagrams of aerogels prepared in Examples 1-6 of the present invention;

[0051] Figure 3 The formaldehyde removal effect of the aerogels of the present invention in comparative example 1 and embodiments 1-6 under low humidity environment;

[0052] Figure 4 This is the formaldehyde removal effect of the aerogels of the present invention's comparative example 1 and embodiments 1-6 in a high humidity environment. DETAILED DESCRIPTION

[0053] The present invention is further described in detail with reference to the following specific examples and accompanying drawings. The processes, conditions, experimental methods, etc. for implementing the present invention, except for those specifically mentioned below, are common knowledge and common common sense in the art and are not particularly limited in the present invention.

[0054] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention, its application, or use. All other embodiments derived by persons of ordinary skill in the art based on the embodiments herein without inventive effort are intended to fall within the scope of protection of the present invention.

[0055] The present invention application discloses a modified hydrophobic chestnut shell fiber aerogel loaded with diamine-modified magnesium-based MOF, its preparation, and application in formaldehyde removal. The modified hydrophobic chestnut shell fiber aerogel loaded with diamine-modified magnesium-based MOF described in the present invention application presents a lamellar structure, which is convenient for the adsorption of formaldehyde. At the same time, by modifying the MOF with diamines, the formaldehyde removal effect in a high humidity environment is greatly improved. The present invention application forms hydrogen bond crosslinks with the carboxyl groups of the chestnut shell fibers through the abundant groups on the surface of the diamine-modified magnesium-based MOF, and self-assembles to form a layered porous structure aerogel without adding an additional crosslinking agent. The abundant pores and amino groups contribute to the adsorption of formaldehyde. At the same time, the hydrophobic modification of the diamine group improves the formaldehyde removal effect of the material in a high humidity environment, and has more practical application prospects.

[0056] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0057] Example 1 A method for preparing a modified hydrophobic chestnut shell fiber aerogel loaded with diamine-modified Mg-MOF, the method comprising the following steps:

[0058] (1) Dried chestnut shells were crushed to obtain chestnut shell powder. 10 g of the powder was immersed in 100 mL of a solution consisting of ethanol and methanol (80:20 v / v), stirred with a glass rod for better homogenization, and allowed to stand at room temperature for 24 h.

[0059] (2) Wash with pure water, then filter under reduced pressure to obtain the residue, and dry it in an oven at 50°C.

[0060] (3) Dissolve 3.5 mol / L Mg(NO3)2·6H2O in a DMF / H2O (40:60 v / v) mixed solvent, then add terephthalic acid with a mass ratio of ligand to Mg(NO3)2·6H2O of 1:15 and stir.

[0061] (4) The mixed solution treated in step (3) was poured into a polytetrafluoroethylene autoclave and heated at 120°C for 12 h to obtain diamine-modified Mg-MOF. The mixture was cooled to room temperature and then taken out, washed with DMF / ethanol alternately for 3 times, and vacuum-dried at 60°C for 6 h to obtain diamine-modified Mg-MOF powder.

[0062] (5) Weigh 15 g of the filter residue obtained in step (2) and 1 g of the dried diamine-modified Mg-MOF powder and disperse them in 30 mL of 9 M hydrochloric acid solution. Mix them evenly by ultrasonication for 2 h. Add 1.5 g of LiF and stir at 40 °C under nitrogen atmosphere for 24 h. Filter and wash to obtain a hydrophobic chestnut shell fiber aerogel loaded with diamine-modified Mg-MOF.

[0063] (6) Weigh 3 g of the hydrophobic chestnut shell fiber aerogel loaded with diamine-modified Mg-MOF obtained in step (5) and disperse it in 60 mL of pure water. Then, slowly add 9 g of hexadecyltrimethylammonium bromide. Ultrasonicate for 3.5 hours.

[0064] (7) Filter, wash with pure water and ethanol three times respectively, and freeze-dry to obtain the modified hydrophobic chestnut shell fiber aerogel loaded with diamine-modified Mg-MOF.

[0065] Example 2 A method for preparing a modified hydrophobic chestnut shell fiber aerogel loaded with diamine-modified Mg-MOF, the method comprising the following steps:

[0066] (1) Dried chestnut shells were crushed to obtain chestnut shell powder. 10 g of the powder was immersed in 100 mL of a solution consisting of ethanol and methanol (80:20 v / v), stirred with a glass rod for better homogenization, and allowed to stand at room temperature for 24 h.

[0067] (2) Wash with pure water, then filter under reduced pressure to obtain the residue, and dry it in an oven at 50°C.

[0068] (3) Dissolve 3.5 mol / L Mg(NO3)2·6H2O in a DMF / H2O (40:60 v / v) mixed solvent, then add terephthalic acid with a mass ratio of ligand to Mg(NO3)2·6H2O of 1:15 and stir.

[0069] (4) The mixed solution treated in step (3) was poured into a polytetrafluoroethylene autoclave and heated at 120°C for 12 h to obtain diamine-modified Mg-MOF. The mixture was cooled to room temperature and then taken out, washed with DMF / ethanol alternately for 3 times, and vacuum-dried at 60°C for 6 h to obtain diamine-modified Mg-MOF powder.

[0070] (5) Weigh 7.5 g of the filter residue obtained in step (2) and 0.5 g of the dried diamine-modified Mg-MOF powder and disperse them in 15 mL of 9 M hydrochloric acid solution. Ultrasonicate for 2 h to mix evenly. Add 0.75 g of LiF and stir at 40 °C under nitrogen atmosphere for 24 h. Filter and wash to obtain the hydrophobic chestnut shell fiber aerogel loaded with diamine-modified Mg-MOF.

[0071] (6) Weigh 3 g of the hydrophobic chestnut shell fiber aerogel loaded with diamine-modified Mg-MOF obtained in step (5) and disperse it in 60 mL of pure water. Then, slowly add 9 g of hexadecyltrimethylammonium chloride. Ultrasonicate for 3.5 hours.

[0072] (7) Filter, wash with pure water and ethanol three times respectively, and freeze-dry to obtain the modified hydrophobic chestnut shell fiber aerogel loaded with diamine-modified Mg-MOF.

[0073] Example 3 A method for preparing a modified hydrophobic chestnut shell fiber aerogel loaded with diamine-modified Mg-MOF, the method comprising the following steps:

[0074] (1) Dried chestnut shells were crushed to obtain chestnut shell powder. 10 g of the powder was immersed in 100 mL of a solution consisting of ethanol and methanol (80:20 v / v), stirred with a glass rod for better homogenization, and allowed to stand at room temperature for 24 h.

[0075] (2) Wash with pure water, then filter under reduced pressure to obtain the residue, and dry it in an oven at 50°C.

[0076] (3) Dissolve 3.5 mol / L Mg(NO3)2·6H2O in a DMF / H2O (40:60 v / v) mixed solvent, then add terephthalic acid with a mass ratio of ligand to Mg(NO3)2·6H2O of 1:15 and stir.

[0077] (4) The mixed solution treated in step (3) was poured into a polytetrafluoroethylene autoclave and heated at 120°C for 12 h to obtain diamine-modified Mg-MOF. The mixture was cooled to room temperature and then taken out, washed with DMF / ethanol alternately for 3 times, and vacuum-dried at 60°C for 6 h to obtain diamine-modified Mg-MOF powder.

[0078] (5) Weigh 30 g of the filter residue obtained in step (2) and 2 g of the dried diamine-modified Mg-MOF powder and disperse them in 15 mL of 9 M hydrochloric acid solution. Mix them evenly by ultrasonication for 2 h. Add 9 g of LiF and stir at 40 °C under nitrogen atmosphere for 24 h. Filter and wash to obtain the hydrophobic chestnut shell fiber aerogel loaded with diamine-modified Mg-MOF.

[0079] (6) Weigh 4.5 g of the hydrophobic chestnut shell fiber aerogel loaded with diamine-modified Mg-MOF obtained in step (5) and disperse it in 90 mL of pure water. Then, slowly add 13.5 g of hexadecyltrimethylammonium bromide. Ultrasonicate for 3.5 hours.

[0080] (7) Filter, wash with pure water and ethanol three times respectively, and freeze-dry to obtain the modified hydrophobic chestnut shell fiber aerogel loaded with diamine-modified Mg-MOF.

[0081] Example 4 A method for preparing a modified hydrophobic chestnut shell fiber aerogel loaded with diamine-modified Mg-MOF, the method comprising the following steps:

[0082] (1) Dried chestnut shells were crushed to obtain chestnut shell powder. 10 g of the powder was immersed in 100 mL of a solution consisting of ethanol and methanol (80:20 v / v), stirred with a glass rod for better homogenization, and allowed to stand at room temperature for 24 h.

[0083] (2) Wash with pure water, then filter under reduced pressure to obtain the residue, and dry it in an oven at 50°C.

[0084] (3) Dissolve 3.5 mol / L Mg(NO3)2·6H2O in a DMF / H2O (40:60 v / v) mixed solvent, then add terephthalic acid with a mass ratio of ligand to Mg(NO3)2·6H2O of 1:15 and stir.

[0085] (4) The mixed solution treated in step (3) was poured into a polytetrafluoroethylene autoclave and heated at 120°C for 12 h to obtain diamine-modified Mg-MOF. The mixture was cooled to room temperature and then taken out, washed with DMF / ethanol alternately for 3 times, and vacuum-dried at 60°C for 6 h to obtain diamine-modified Mg-MOF powder.

[0086] (5) Weigh 15 g of the filter residue obtained in step (2) and 1 g of the dried diamine-modified Mg-MOF powder and disperse them in 30 mL of 9 M hydrochloric acid solution. Mix them evenly by ultrasonication for 2 h. Add 1.5 g of LiF and stir at 40 °C under nitrogen atmosphere for 24 h. Filter and wash to obtain a hydrophobic chestnut shell fiber aerogel loaded with diamine-modified Mg-MOF.

[0087] (6) Weigh 3 g of the hydrophobic chestnut shell fiber aerogel loaded with diamine-modified Mg-MOF obtained in step (5) and disperse it in 60 mL of pure water. Then, slowly add 6 g of hexadecyltrimethylammonium bromide and 3 g of hexadecyltrimethylammonium chloride. Ultrasonicate for 3.5 hours.

[0088] (7) Filter, wash with pure water and ethanol three times respectively, and freeze-dry to obtain the modified hydrophobic chestnut shell fiber aerogel loaded with diamine-modified Mg-MOF.

[0089] Example 5 A method for preparing a modified hydrophobic chestnut shell fiber aerogel loaded with diamine-modified Mg-MOF, the method comprising the following steps:

[0090] (1) Dried chestnut shells were crushed to obtain chestnut shell powder. 10 g of the powder was immersed in 100 mL of a solution consisting of ethanol and methanol (80:20 v / v), stirred with a glass rod for better homogenization, and allowed to stand at room temperature for 24 h.

[0091] (2) Wash with pure water, then filter under reduced pressure to obtain the residue, and dry it in an oven at 50°C.

[0092] (3) Dissolve 3.5 mol / L Mg(NO3)2·6H2O in a DMF / H2O (40:60 v / v) mixed solvent, then add terephthalic acid with a mass ratio of ligand to Mg(NO3)2·6H2O of 1:15 and stir.

[0093] (4) The mixed solution treated in step (3) was poured into a polytetrafluoroethylene autoclave and heated at 120°C for 12 h to obtain diamine-modified Mg-MOF. The mixture was cooled to room temperature and then taken out, washed with DMF / ethanol alternately for 3 times, and vacuum-dried at 60°C for 6 h to obtain diamine-modified Mg-MOF powder.

[0094] (5) Weigh 15 g of the filter residue obtained in step (2) and 1 g of the dried diamine-modified Mg-MOF powder and disperse them in 30 mL of 9 M hydrochloric acid solution. Mix them evenly by ultrasonication for 2 h. Add 1.5 g of LiF and stir at 40 °C under nitrogen atmosphere for 24 h. Filter and wash to obtain a hydrophobic chestnut shell fiber aerogel loaded with diamine-modified Mg-MOF.

[0095] (6) Weigh 3 g of the hydrophobic chestnut shell fiber aerogel loaded with diamine-modified Mg-MOF obtained in step (5) and disperse it in 60 mL of pure water. Then, slowly add 3 g of hexadecyltrimethylammonium bromide and 6 g of hexadecyltrimethylammonium chloride. Ultrasonicate for 3.5 hours.

[0096] (7) Filter, wash with pure water and ethanol three times respectively, and freeze-dry to obtain the modified hydrophobic chestnut shell fiber aerogel loaded with diamine-modified Mg-MOF.

[0097] Example 6 A method for preparing a modified hydrophobic chestnut shell fiber aerogel loaded with diamine-modified Mg-MOF, the method comprising the following steps:

[0098] (1) Dried chestnut shells were crushed to obtain chestnut shell powder. 10 g of the powder was immersed in 100 mL of a solution consisting of ethanol and methanol (80:20 v / v), stirred with a glass rod for better homogenization, and allowed to stand at room temperature for 24 h.

[0099] (2) Wash with pure water, then filter under reduced pressure to obtain the residue, and dry it in an oven at 50°C.

[0100] (3) Dissolve 3.5 mol / L Mg(NO3)2·6H2O in a DMF / H2O (40:60 v / v) mixed solvent, then add terephthalic acid with a mass ratio of ligand to Mg(NO3)2·6H2O of 1:15 and stir.

[0101] (4) The mixed solution treated in step (3) was poured into a polytetrafluoroethylene autoclave and heated at 120°C for 12 h to obtain diamine-modified Mg-MOF. The mixture was cooled to room temperature and then taken out, washed with DMF / ethanol alternately for 3 times, and vacuum-dried at 60°C for 6 h to obtain diamine-modified Mg-MOF powder.

[0102] (5) Weigh 15 g of the filter residue obtained in step (2) and 1 g of the dried diamine-modified Mg-MOF powder and disperse them in 30 mL of 9 M hydrochloric acid solution. Mix them evenly by ultrasonication for 2 h. Add 1.5 g of LiF and stir at 40 °C under nitrogen atmosphere for 24 h. Filter and wash to obtain a hydrophobic chestnut shell fiber aerogel loaded with diamine-modified Mg-MOF.

[0103] (6) Weigh 2 g of the hydrophobic chestnut shell fiber aerogel loaded with diamine-modified Mg-MOF obtained in step (5) and disperse it in 40 mL of pure water. Then, slowly add 3 g of hexadecyltrimethylammonium bromide and 3 g of hexadecyltrimethylammonium chloride. Ultrasonicate for 3.5 hours.

[0104] (7) Filter, wash with pure water and ethanol three times respectively, and freeze-dry to obtain the modified hydrophobic chestnut shell fiber aerogel loaded with diamine-modified Mg-MOF.

[0105] Comparative Example 1 A method for preparing a hydrophobic chestnut shell fiber aerogel loaded with diamine-modified Mg-MOF, the method comprising the following steps:

[0106] (1) Dried chestnut shells were crushed to obtain chestnut shell powder. 10 g of the powder was immersed in 100 mL of a solution consisting of ethanol and methanol (80:20 v / v), stirred with a glass rod for better homogenization, and allowed to stand at room temperature for 24 h.

[0107] (2) Wash with pure water, then filter under reduced pressure to obtain the residue, and dry it in an oven at 50°C.

[0108] (3) Dissolve 3.5 mol / L Mg(NO3)2·6H2O in a DMF / H2O (40:60 v / v) mixed solvent, then add terephthalic acid with a mass ratio of ligand to Mg(NO3)2·6H2O of 1:15 and stir.

[0109] (4) The mixed solution treated in step (3) was poured into a polytetrafluoroethylene autoclave and heated at 120°C for 12 h to obtain diamine-modified Mg-MOF. The mixture was cooled to room temperature and then taken out, washed with DMF / ethanol alternately for 3 times, and vacuum-dried at 60°C for 6 h to obtain diamine-modified Mg-MOF powder.

[0110] (5) Weigh 15 g of the filter residue from step (2) and 1 g of the dried diamine-modified Mg-MOF powder and disperse them in 30 mL of 9 M hydrochloric acid solution. Ultrasonicate for 2 h to mix evenly. Add 1.5 g of LiF and stir at 40 °C under nitrogen atmosphere for 24 h. Filter, wash, and freeze-dry to obtain a hydrophobic chestnut shell fiber aerogel loaded with diamine-modified Mg-MOF.

[0111] The experimental results of Examples 1-6 of the present invention are as follows:

[0112] SEM: Through SEM, it can be observed that the aerogels prepared in Examples 1-6 of the present invention all have a multi-layer structure, and the surface is covered with uneven flaky structures.

[0113] Example 7 Nitrogen adsorption and desorption test

[0114] The adsorption-desorption isotherm of N2 at 298 K was tested using the adsorption instrument ASAP 2460. The specific experimental results are shown in Figure 2 The aerogels prepared in Examples 1-6 of the present invention all have a mesoporous structure, and the aerogel prepared in Example 3 of the present invention has the best adsorption performance.

[0115] Example 8 Formaldehyde adsorption experiment 1

[0116] The temperature and humidity in a 200L sealed chamber were controlled at 27°C and 30%. A heating plate was preheated to 80°C. 150 μl of formaldehyde solution was dripped into a glass petri dish and placed on the heating plate for 30 minutes to allow the formaldehyde to completely evaporate. Then, 10 g of the composite film (i.e., the aerogel prepared in Examples 1-6 or Comparative Example 1 of the present invention) was placed in the dish. Samples were taken at different time points using an atmospheric sampler, and the values ​​were recorded. Figure 3 As shown, compared with the blank group without composite membrane, the composite membranes prepared in Examples 1-6 of the present invention and the composite membrane prepared in Control Example 1 (Control Group 1) can effectively remove formaldehyde under dry conditions, and Example 3 of the present invention can remove up to 99% of formaldehyde within 24 hours.

[0117] Example 9 Formaldehyde adsorption experiment 2

[0118] The temperature and humidity in a 200L sealed chamber were controlled at 27°C and 70%. A heating plate was preheated to 90°C. 150 μl of formaldehyde solution was dripped into a glass petri dish and placed on the heating plate for 30 minutes to completely volatilize the formaldehyde. Then, 10 g of the composite film (i.e., the aerogel prepared in Examples 1-6 or Comparative Example 1 of the present invention) was placed in the dish. Samples were taken at different time points using an atmospheric sampler, and the values ​​were recorded. Figure 4 As shown, compared to the blank control group without composite aerogel, the composite membranes prepared in Examples 1-6 of the present invention can effectively remove formaldehyde. Among them, Example 4 of the present invention can still remove 99% of formaldehyde within 24 hours. The composite aerogel prepared in Control Example 1 (Control Group 1) has a formaldehyde removal effect that decreases to 60% under high humidity.

[0119] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as those commonly understood by those skilled in the art to which this application relates. The terms used in this specification are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0120] As used in the present application, the term "comprising" is an open expression, that is, including the contents specified in the present application, but not excluding other contents.

[0121] As used in this application, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0122] Although the embodiments of the present disclosure have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and alterations may be made to the embodiments without departing from the principles and spirit of the present disclosure, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a modified hydrophobic chestnut shell fiber aerogel loaded with diamine-modified magnesium-based MOF, characterized in that: The method comprises the following steps: (1) Immerse chestnut shell powder in a solution consisting of ethanol and methanol, stir, and allow to stand at room temperature; (2) then washing with purified water, filtering under reduced pressure to obtain the residue and drying; (3) A metal salt is dissolved in a DMF / H2O mixed solvent, and a ligand is added and stirred; the metal salt is selected from any one of Mg(NO3)2·6H2O, MgBr2, Mg(CH3COO)2·4H2O, and MgCl2; the ligand is one or both of terephthalic acid and 2,5-dihydroxyterephthalic acid; the mass ratio of the metal salt to the ligand is 1:1-1:20; (4) heating the mixed solution after stirring in step (3) to obtain a diamine-modified magnesium-based MOF, cooling the solution, taking it out, washing it with DMF / ethanol alternately, and vacuum drying it to obtain a diamine-modified magnesium-based MOF powder; the heating temperature is 120-200° C.; the heating time is 6-24 hours; (5) The filter residue obtained in step (2) and the diamine-modified magnesium-based MOF powder obtained in step (4) are dispersed in a 9M hydrochloric acid solution, ultrasonically mixed, LiF is added, stirred, filtered, and washed to obtain a hydrophobic chestnut shell fiber aerogel loaded with diamine-modified magnesium-based MOF; the weight ratio of the filter residue to the diamine-modified magnesium-based MOF powder is 10:1-50:1; the mass ratio of the diamine-modified magnesium-based MOF to LiF is 1:1-1:10; the mass ratio of the diamine-modified magnesium-based MOF to hydrochloric acid is 1 g:10 mL-1 g:50 mL; (6) The hydrophobic chestnut shell fiber aerogel loaded with diamine-modified magnesium-based MOF is dispersed in pure water, ultrasonicated and modified by adding a modifier to obtain the modified hydrophobic chestnut shell fiber aerogel loaded with diamine-modified magnesium-based MOF; the mass ratio of the hydrophobic chestnut shell fiber aerogel loaded with diamine-modified magnesium-based MOF to pure water is (1-20): (1-100); the mass ratio of the hydrophobic chestnut shell fiber aerogel loaded with diamine-modified magnesium-based MOF to the modifier is (1-2): (1-10).

2. The method according to claim 1, wherein In step (1), the volume ratio of methanol to ethanol is 100-20:20; the standing time is 1h-48h; and the mass / volume ratio of the solution consisting of the chestnut shell powder, methanol and ethanol is (1-10) g: (10-100) mL.

3. The method according to claim 1, wherein In step (2), the drying temperature is 25-70°C; In step (3), the volume ratio of DMF and H2O in the DMF / H2O mixed solvent is 40:40-100; the concentration of the metal salt is 0.5-5 mol / L.

4. The method according to claim 1, wherein In step (4), the vacuum drying temperature is 25-70°C; the vacuum drying time is 6-24 hours.

5. The method according to claim 1, wherein In step (5), the ultrasonic time is 0.5h-3h; the stirring time is 10h-30h; and the stirring temperature is 20-50°C.

6. The method according to claim 1, wherein In step (6), the modifier is one of cetyltrimethylammonium bromide and cetyltrimethylammonium chloride or a mixture thereof; and the ultrasonication time is 1 h to 4 h.

7. A modified hydrophobic chestnut shell fiber aerogel loaded with diamine-modified magnesium-based MOF, characterized in that: The modified hydrophobic chestnut shell fiber aerogel loaded with diamine-modified magnesium-based MOF is prepared by the method according to any one of claims 1 to 6.

8. Application of a modified hydrophobic chestnut shell fiber aerogel loaded with diamine-modified magnesium-based MOF in formaldehyde removal, characterized in that: The modified hydrophobic chestnut shell fiber aerogel loaded with diamine-modified magnesium-based MOF is the modified hydrophobic chestnut shell fiber aerogel loaded with diamine-modified magnesium-based MOF as claimed in claim 7.

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