A metal organic framework adsorbent material, its preparation method and use

Abstract

The present disclosure relates to a kind of metal organic framework adsorption material and its preparation method and use, the method comprises: S1, the suspension of containing metal organic framework raw material is carried out ultraviolet irradiation treatment, obtain the light product;S2, the light product is carried out solid-liquid separation, obtain the solid product;Wherein, the wavelength of ultraviolet irradiation treatment is 200-400nm.The method provided in the present disclosure can efficiently and accurately regulate defect concentration, the crystal structure and morphology of the material prepared are intact, and have more active sites.The metal organic framework adsorption material provided in the present disclosure has excellent adsorption performance when used for adsorbing antibiotics.

Description

Technical Field

[0001] This disclosure pertains to the field of adsorption materials, specifically relating to a metal-organic framework adsorption material, its preparation method, and its applications. Background Technology

[0002] Metal-organic frameworks (MOFs) are crystalline porous materials with a periodic network structure formed by the self-assembly of metal ions or metal clusters with organic ligands through coordination bonds. Due to their high specific surface area, tunable pore structure, and functionalized pore environment, they exhibit great application potential in fields such as gas storage, separation, catalysis, sensing, and drug delivery.

[0003] However, the coordination of metal nodes in perfectly crystalline MOFs is usually saturated, resulting in a limited number of active sites, which restricts their application in certain demanding catalytic reactions. To overcome this limitation, researchers have developed various methods to introduce defects into MOFs. The introduction of defects can create more open metal sites, adjust the electronic structure of the material, and alter its pore environment and hydrophilicity / hydrophobicity, thereby significantly enhancing its physicochemical properties. However, existing methods for introducing defects still have many problems. For example, modulation synthesis directly synthesizes defective MOFs by changing the feed ratio, adding regulators, or competitive ligands during the synthesis process. However, this method has poor controllability, making it difficult to precisely control the defect concentration and easily affecting the crystallinity of the material. Another example is post-synthesis treatment methods (such as acid treatment, alkali treatment, high-temperature pyrolysis, etc.), which, due to the harsh conditions, can easily lead to partial collapse of the framework or the introduction of impurities, damaging the integrity of the material, and the synthesis process is not environmentally friendly. Summary of the Invention

[0004] The purpose of this invention is to provide a metal-organic framework adsorbent material, its preparation method, and its applications. The method provided by this invention can efficiently and precisely control the defect concentration, and the prepared material has a well-preserved crystal structure and morphology, as well as more active sites, resulting in significantly improved adsorption performance.

[0005] To achieve the above objectives, a first aspect of the present invention provides a method for preparing metal-organic framework adsorbent materials, the method comprising: S1. The suspension containing metal-organic framework raw materials is subjected to ultraviolet irradiation to obtain the photo-irradiated product. S2. Perform solid-liquid separation on the light-irradiated product to obtain a solid product; The wavelength of the ultraviolet irradiation treatment is 200-400nm; The metal-organic framework material includes at least one of zirconium-based metal-organic framework materials, titanium-based metal-organic framework materials, zinc-based metal-organic framework materials, and copper-based metal-organic framework materials.

[0006] Optionally, the metal-organic framework raw material includes metal-organic framework materials; Preferably, the metal-organic framework material includes at least one of MOF-808, UiO-66, and Cu-BTC.

[0007] Optionally, the metal-organic framework raw material further includes metal-organic framework materials containing azophenyl groups; Optionally, the method further includes: mixing the metal-organic framework material with a carboxylic acid compound containing an azo bond to obtain the metal-organic framework material containing an azophenyl group; Optionally, the amount of carboxylic acid compound containing azo bonds added is 0.01-0.5g relative to 1g of metal-organic framework material; Optionally, the carboxylic acid compound containing an azo bond includes at least one of 4,4'-azobenzenediacarboxylic acid, 3,3'-azobenzenediacarboxylic acid, and 2,2'-azobenzenediacarboxylic acid.

[0008] Optionally, the method satisfies at least one of the following conditions: The ultraviolet irradiation treatment is carried out under stirring; the stirring speed is 50-2000 rpm; The ultraviolet irradiation treatment is performed under a first ultrasound; the frequency of the first ultrasound is 20-1000 kHz. The wavelength of the ultraviolet irradiation treatment is 300-370 nm; The optical power of the ultraviolet irradiation treatment is 2-100mW; The ultraviolet irradiation treatment is carried out at a temperature of 0-60℃ for a duration of 0.3-48h. The atmosphere for the ultraviolet irradiation treatment is air.

[0009] Optionally, the content of the metal-organic framework raw material in the suspension is 1-50 mg / mL.

[0010] Optionally, the method further includes: S0, mixing the metal-organic framework raw material with an organic solvent to obtain the suspension containing the metal-organic framework raw material; Preferably, the mixing is performed under a second ultrasound; the frequency of the second ultrasound is 20-1000 kHz, and the duration is 5-120 min.

[0011] Optionally, the organic solvent includes at least one of water, alcohols, amines, ketones, and amides having 1-4 carbon atoms; Preferably, the organic solvent includes at least one selected from water, methanol, ethanol, isopropanol, N,N-dimethylformamide, and acetone.

[0012] Optionally, the method further includes washing and drying the solid product; The drying conditions include a temperature of 60-150℃ and a time of 3-24h.

[0013] A second aspect of the present invention provides a metal-organic framework adsorbent material prepared by the method described in the first aspect of the present invention; Among them, A in the ultraviolet-visible absorption spectrum of the metal-organic framework adsorbent material 430 / A 320 The value is 0.64-0.8; where A 320 This refers to the absorbance at 320 nm in the ultraviolet-visible absorption spectrum of the metal-organic framework adsorbent material; A 430 This refers to the absorbance at 430 nm in the ultraviolet-visible absorption spectrum of the metal-organic framework adsorbent material; and / or, A in the XPS O1s spectrum of the metal-organic framework adsorbent material 羟基 / A 晶格 It is 0.2-0.7; where A 晶格 This refers to the peak area of ​​the lattice oxygen characteristic peak in the XPS O1s spectrum of the metal-organic framework adsorbent; A 羟基 It refers to the peak area of ​​the characteristic hydroxyl oxygen peak in the XPS O1s spectrum of the metal-organic framework adsorbent material.

[0014] A third aspect of the present invention provides the use of the metal-organic framework adsorbent material described in the second aspect of the present invention for adsorbing antibiotics.

[0015] Through the above technical solution, this invention utilizes ultraviolet light to induce local structural reconstruction of metal clusters in metal-organic framework (MOF) materials. Specifically, coordination bond breakage forms ligand-deficient defects, exposing numerous unsaturated metal sites. Simultaneously, lattice oxygen, previously obscured by ligands or solvent molecules, is exposed, increasing the lattice oxygen content. Furthermore, coordinated water or solvent molecules desorb from the defect sites, reducing defect-related oxygen content and exposing unsaturated metal sites. These sites further adsorb water molecules or hydroxyl species, significantly increasing the surface hydroxyl oxygen content. The increased lattice oxygen exposure and the significant increase in hydroxyl oxygen species jointly demonstrate the effective enhancement of photoinduced defect content. Moreover, the defect type in the MOF material is primarily ligand-deficient, while metal cluster nodes and secondary structural units remain intact, maintaining the long-range periodicity of the crystal and effectively preserving the integrity of the crystal structure and morphology. In summary, the preparation method of this invention generates photoinduced defects in MOFs materials by irradiating them with ultraviolet light, exposing the active sites of MOFs (such as open metal sites or polar pore environments). Furthermore, ultraviolet irradiation does not damage the framework integrity of the MOFs materials, effectively maintaining the crystal structure and morphology of the prepared MOFs materials. Therefore, the method disclosed in this invention significantly improves the adsorption performance and structural stability of MOFs materials. In addition, this method is applicable to a variety of ultraviolet-responsive MOFs materials, has good versatility, and uses only ultraviolet light and organic solvents, without introducing acids, alkalis, or other chemical modifiers, thus avoiding secondary pollution.

[0016] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0017] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the following detailed description to explain the invention, but do not constitute a limitation thereof. In the drawings: Figure 1 These are XRD comparison images of the metal-organic framework raw materials used in Examples 1 and 5 of this invention.

[0018] Figure 2 The image shows a comparison of the XRD patterns of the metal-organic framework raw materials used in Example 1 of this invention and the prepared metal-organic framework materials.

[0019] Figure 3 The images shown are SEM images of the metal-organic framework raw materials prepared in Examples 1-5 of this invention, where (a) is MOF-808, (b) is AZO1-MOF-808, (c) is AZO2-MOF-808, (d) is AZO3-MOF-808, and (e) is AZO4-MOF-808.

[0020] Figure 4The image shows a SEM image of the metal-organic framework adsorbent material prepared in Example 1.

[0021] Figure 5 The images show the TEM spectra of the metal-organic framework raw materials and the metal-organic framework adsorbent materials prepared in Examples 1 and 5 of this invention, where (a) is the metal-organic framework raw material used in Example 5; (b) is the metal-organic framework material prepared in Example 5; (c) is the metal-organic framework raw material used in Example 1; and (d) is the metal-organic framework material prepared in Example 1.

[0022] Figure 6 The above are XPS spectra of the metal-organic framework raw materials and the prepared metal-organic framework adsorbents used in Examples 1 and 5 of this invention; wherein, LS-AZO2-MOF-808 is the metal-organic framework adsorbent prepared in Example 1; AZO2-MOF-808 is the metal-organic framework raw material used in Example 1; LS-MOF-808 is the metal-organic framework adsorbent prepared in Example 5; MOF-808 is the metal-organic framework raw material used in Example 5.

[0023] Figure 7 The images show the fine structure spectra of XPS O1s of the metal-organic framework raw materials and the prepared metal-organic framework materials used in Examples 1 and 5 of this invention, wherein (a) is the metal-organic framework raw material used in Example 5; (b) is the metal-organic framework raw material used in Example 1; (c) is the metal-organic framework material prepared in Example 1; and (d) is the metal-organic framework material prepared in Example 5.

[0024] Figure 8 The image shows the ultraviolet-visible absorption spectrum of the metal-organic framework material prepared in Example 1 of this invention. Detailed Implementation

[0025] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.

[0026] The first aspect of this disclosure provides a method for preparing metal-organic framework adsorbent materials, the method comprising: S1, subjecting a suspension containing a metal-organic framework raw material to ultraviolet irradiation to obtain a photo-irradiated product; S2, subjecting the photo-irradiated product to solid-liquid separation to obtain a solid-phase product; wherein the wavelength of the ultraviolet irradiation is 200-400 nm; and the metal-organic framework raw material comprises at least one of zirconium-based metal-organic framework materials, titanium-based metal-organic framework materials, zinc-based metal-organic framework materials, and copper-based metal-organic framework materials.

[0027] The preparation method of this application exposes active sites in MOF materials through ultraviolet light irradiation, accurately synthesizing defective MOFs while effectively maintaining the crystal structure and morphology of the prepared MOF materials and avoiding framework collapse, thereby significantly improving the adsorption performance of MOF materials. Furthermore, the method provided in this application is applicable to a variety of MOF materials that respond to ultraviolet light, exhibiting good versatility, and uses only ultraviolet light and organic solvents, without introducing additional acids, bases, or other chemical modifiers, thus avoiding secondary pollution.

[0028] In one embodiment, the metal-organic framework raw material includes metal-organic framework materials.

[0029] In a further embodiment, the metal-organic framework raw material further includes a metal-organic framework material containing azophenyl groups.

[0030] In a further embodiment, the method of this disclosure may include the step of modifying the metal-organic framework material with an azo ligand compound. Specifically, the method further includes: mixing the metal-organic framework material with a carboxylic acid compound containing an azo bond to obtain the metal-organic framework material containing an azophenyl group. In the above embodiments, the carboxylic acid compound containing an azo bond is used as a photoresponsive ligand, which normally coordinates with the metal cluster nodes in a thermodynamically stable trans configuration to form a long-range ordered crystal framework. Under ultraviolet light irradiation, the azophenyl group undergoes photoisomerization to a cis configuration. Due to the significant difference in geometric dimensions and dipole moments, the cis configuration can generate local stress within the MOF channels, forcing the coordination bonds to dynamically break or distort, forming ligand-deficient defects. In this embodiment, using a metal-organic framework material containing an azophenyl group allows for more precise control of the cis / trans configuration ratio in the framework by adjusting the ultraviolet irradiation dose, thereby achieving more precise control and improvement of the adsorption performance of the prepared adsorbent material for tetracycline. Furthermore, ultraviolet light only triggers ligand spatial configuration changes and does not provide the high energy required to disrupt the entire coordination network (unlike strong acids H+). + The thermal relaxation of the partial cis configuration after irradiation (attack or high-temperature phonon energy) avoids the continuous accumulation of rigid stress, which is more conducive to maintaining the crystal structure stability of MOF materials. In addition, the defect type of MOF materials is mainly ligand missing type, and the metal cluster nodes and secondary structural units remain intact, so that the long-range periodicity of the crystal can be maintained, thereby effectively maintaining the integrity of the crystal structure and morphology.

[0031] In a more preferred embodiment, the carboxylic acid compound containing an azo bond includes at least one selected from 4,4'-azobenzenediacarboxylic acid, 3,3'-azobenzenediacarboxylic acid, and 2,2'-azobenzenediacarboxylic acid. In a preferred embodiment, the carboxylic acid compound containing an azo bond is 4,4'-azobenzenediacarboxylic acid. The above-mentioned preferred types of azo ligand compounds are used to modify metal-organic framework materials (MOFs), resulting in MOFs with more efficient light response and significantly improved adsorption performance.

[0032] In one embodiment, the amount of a carboxylic acid compound containing an azo bond added relative to 1g of metal-organic framework material is 0.01g-0.5g, preferably 0.05-0.1g. In the above embodiment, controlling the amount of the carboxylic acid compound containing an azo bond within the preferred range of this application allows for the doping of a suitable amount of azobenzene ligand into the MOF material, thereby generating a suitable amount of cis isomers under ultraviolet irradiation. Furthermore, a synergistic effect exists between the preferred doping amount and the preferred irradiation dose, and this synergistic effect can further regulate the proportion of cis isomers and prevent the MOF material pores from being blocked by excessive ligands. This results in the metal-organic framework material possessing both a more suitable photoinduced defect concentration and superior unobstructed pores, thereby further improving the adsorption efficiency of the prepared metal-organic framework adsorbent material for tetracycline.

[0033] In one specific embodiment, relative to 1g of metal-organic framework material, the amount of carboxylic acid compound containing azo bonds added can be any amount within the range formed by any one or any two of the following: 0.05g, 0.06g, 0.07g, 0.08g, 0.09g, 0.1g, 0.15g, 0.2g, 0.25g, 0.3g, 0.35g, 0.4g, 0.45g, and 0.5g.

[0034] In a preferred embodiment, the metal-organic framework raw material includes at least one of MOF-808, UiO-66, and Cu-BTC. The method provided in this application is applicable to a variety of MOF materials that respond to ultraviolet light, and has good versatility. In a preferred embodiment, using a metal-organic framework raw material containing MOF-808 is more conducive to the functionalization of azobenzene.

[0035] In a preferred embodiment, the wavelength of the ultraviolet irradiation treatment is 300-370 nm; specifically, the wavelength of the ultraviolet irradiation treatment can be any wavelength within the range of any one or any two of 300 nm, 305 nm, 310 nm, 315 nm, 320 nm, 325 nm, 330 nm, 335 nm, 340 nm, 345 nm, 350 nm, 355 nm, 360 nm, 365 nm, and 370 nm. In a more preferred embodiment, the wavelength of the ultraviolet irradiation treatment is 365 nm. By using the preferred wavelength range defined in this application, the defect concentration in the material can be further effectively and precisely controlled, so that the prepared defective MOFs material has more active sites; at the same time, the crystal structure and morphology of the defective MOFs material can be kept intact, thereby further improving the adsorption performance of the material.

[0036] In one embodiment, the light power of the ultraviolet irradiation treatment is 2-100mW, preferably 6-20mW. In the above embodiment, using the preferred light power range defined in this application can further promote the effective increase of the photoinduced defect content, further increase the open metal sites and active adsorption sites of the adsorbent material, and effectively improve the adsorption performance.

[0037] In one specific embodiment, the light power of the ultraviolet irradiation treatment can be any light power within the range of any one or any two of 6mW, 7mW, 8mW, 9mW, 10mW, 11mW, 12mW, 13mW, 14mW, 15mW, 16mW, 17mW, 18mW, 19mW, and 20mW. In the above embodiment, the ultraviolet irradiation dose, within a preferred range, can regulate the proportion of photoisomerization of the azophenyl group from the trans configuration to the cis configuration, obtaining a more suitable content of cis ligand, thereby more efficiently and precisely controlling the defect concentration and further improving the adsorption performance of the prepared adsorbent material for tetracycline.

[0038] In one specific embodiment, the ultraviolet irradiation treatment time is 0.3-48 hours, preferably 0.3-3 hours. In the above embodiments, the inventors of this application have discovered that when the light treatment time is within the above-preferred range, photocorrosion caused by prolonged ultraviolet irradiation can be avoided, as well as partial structural damage or pore collapse, thereby preventing a decrease in the material's adsorption capacity.

[0039] Further research by the inventors of this application has revealed that, within the aforementioned preferred irradiation time and irradiation power range, a more suitable irradiation dose can be obtained. This suitable irradiation dose can linearly adjust the generation rate and cis configuration ratio of cis ligands in the framework, resulting in a more suitable coordination dislocation probability caused by the cis configuration. This leads to the introduction of a more suitable defect concentration in the MOF material, thereby achieving precise control over the material's adsorption capacity.

[0040] In one specific embodiment, the temperature of the ultraviolet irradiation treatment is 0-60℃, preferably 0-30℃. In the above embodiment, controlling the temperature within a suitable range can effectively suppress the thermal relaxation rotation of cis-azobenzene, maintaining a high cis proportion and sufficient defective active sites; simultaneously, it avoids structural degradation of the MOF framework due to thermal stress, maintaining pore integrity; and in conjunction with the thermodynamic characteristics of the exothermic adsorption of tetracycline, it shifts the adsorption equilibrium in a favorable direction, improving adsorption capacity and stability.

[0041] In one specific embodiment, the ultraviolet irradiation treatment is carried out under stirring; the stirring speed is 50-2000 rpm, preferably 100-1000 rpm. In another embodiment, the ultraviolet irradiation treatment is carried out under first ultrasound; the frequency of the first ultrasound is 20-1000 kHz, preferably 20-100 kHz. In the above embodiments, carrying out the ultraviolet irradiation treatment under stirring or ultrasound can make the metal-organic framework raw materials in the suspension more uniformly distributed, thereby making the ultraviolet irradiation more uniform, and further improving the effect of ultraviolet irradiation treatment. This results in the prepared defective MOFs material having more active sites, further improving the material's adsorption performance for antibiotics.

[0042] In a preferred embodiment, the ultraviolet irradiation treatment is carried out under stirring. In the above embodiment, the stirring treatment ensures uniform light irradiation without damaging the material structure, effectively increasing the total number of effective active sites per unit mass of material, thus further enhancing the adsorption performance.

[0043] In one specific embodiment, the content of the metal-organic framework raw material in the suspension is 1-50 mg / mL, preferably 5-20 mg / mL. In the above embodiment, controlling the suspension concentration within a suitable range ensures that the ultraviolet light penetration depth matches the bulk density of the active material, balancing sufficient light irradiation with material loading. Within the preferred concentration range, ultraviolet light can penetrate more fully into the deeper layers of the suspension, ensuring that both the internal and surface MOF particles receive equivalent light irradiation. This allows for uniform azobenzene isomerization throughout the system, avoiding the uneven distribution of surface modification and unreacted internal components at high concentrations. Uniform and sufficient isomerization modification maximizes the defect concentration and the number of active sites, thus further improving the adsorption efficiency for tetracycline.

[0044] In one specific embodiment, the method further includes: S0, mixing the metal-organic framework raw material with an organic solvent to obtain the suspension containing the metal-organic framework raw material. In a preferred embodiment, the mixing is performed under a second ultrasound; the frequency of the second ultrasound is 20-1000 kHz, preferably 20-100 kHz, and the duration is 5-120 min, preferably 10-60 min.

[0045] In one specific embodiment, the organic solvent includes at least one of water, alcohols, amines, and ketones having 1-4 carbon atoms; in a preferred embodiment, the organic solvent includes at least one of water, methanol, ethanol, isopropanol, N,N-dimethylformamide, and acetone.

[0046] In one specific embodiment, the method further includes washing and drying the solid product. In another specific embodiment, the drying conditions include a temperature of 60-150°C, preferably 60-120°C, and a time of 3-24 hours, preferably 6-12 hours.

[0047] The second aspect of this disclosure provides a metal-organic framework adsorbent material prepared using the method described in the first aspect of this disclosure.

[0048] In one embodiment, the UV-Vis absorption spectrum of the metal-organic framework adsorbent material contains A 430 / A 320 The value is 0.64-0.8; where A 320 This refers to the absorbance at 320 nm in the ultraviolet-visible absorption spectrum of the metal-organic framework adsorbent material; A 430 It refers to the absorbance at 430 nm in the ultraviolet-visible absorption spectrum of the metal-organic framework adsorbent material.

[0049] In this disclosure, A 430 / A 320 This refers to the ratio of the cis isomer (Cis) and trans isomer (Trans) of azobenzene in the MOF structure. In the above embodiment, A 430 / A 320 Within the preferred range, the photoisomerization degree and cis configuration ratio of the azophenyl groups in the material are more favorable, indicating that the ultraviolet irradiation dose in the preparation process is within the preferred range, which is beneficial to improving the adsorption performance of the prepared material.

[0050] In one embodiment, the A in the XPS O1s spectrum of the metal-organic framework adsorbent material 羟基 / A 晶格 The value is 0.2-0.7, preferably 0.6-0.7; wherein, A 晶格This refers to the peak area of ​​the lattice oxygen characteristic peak in the XPS O1s spectrum of the metal-organic framework adsorbent material, with a binding energy of 529.5-530.5 eV; A 羟基 It refers to the peak area of ​​the characteristic hydroxyl oxygen peak in the XPS O1s spectrum of the metal-organic framework adsorbent material, with a binding energy of 532.5-533.5 eV.

[0051] In the XPS O1s spectrum, the metal clusters in the metal-organic framework adsorbent material prepared in this application undergo local structural reconstruction. Specifically, coordination bond breakage forms ligand-deficient defects, exposing numerous unsaturated metal sites. Simultaneously, lattice oxygen, previously masked by ligands or solvent molecules, is exposed, increasing the lattice oxygen content. Furthermore, coordinated water or solvent molecules desorb from the defect sites, reducing the defect-related oxygen area at 531.0-532.0 eV and exposing unsaturated metal sites. These sites further adsorb water molecules or hydroxyl species, significantly increasing the surface hydroxyl oxygen content (approximately 532.5-533.5 eV). This phenomenon is consistent with the photoinduced defect generation process, further confirming the effective enhancement of photoinduced defect content. In the above embodiments, by controlling each parameter within the preferred range, A... 羟基 / A 晶格 By controlling the value within an appropriate range, the photoinduced defect content of metal-organic framework materials can be further increased, allowing the materials to expose more open metal sites and active adsorption sites, thereby further improving the adsorption performance of the materials for tetracycline.

[0052] The metal-organic framework adsorbent material prepared in this application has a well-preserved crystal structure and morphology, an appropriate defect concentration, and more active sites, resulting in significantly improved adsorption performance.

[0053] The third aspect of this disclosure provides a method for using the metal-organic framework adsorbent material described in the second aspect of this disclosure to adsorb antibiotics.

[0054] In a more specific embodiment, the adsorbent material is used to adsorb tetracycline.

[0055] The metal-organic framework material provided in this application exhibits excellent adsorption performance when used as an adsorbent material, with a high adsorption rate for antibiotics and effectively improved adsorption efficiency.

[0056] The present invention will be further illustrated by the following examples, but the invention is not limited thereto. All raw materials used in the examples and comparative examples are commercially available.

[0057] Example 1 S0. Mix 100 mg of metal-organic framework (MOF) raw material with 20 mL of organic solvent under ultrasonication for 10 min to obtain a suspension containing the MOF raw material; wherein, the MOF raw material is MOF-808 (denoted as AZO2-MOF-808) containing azophenyl groups. The MOF-808 is prepared by a laboratory solvothermal method: The specific feed amounts are as follows: Weigh 1.05 g (4.5 mmol) ZrCl4 (zirconium tetrachloride) as the metal ion source, and 0.31 g (1.5 mmol) trimesic acid (H3BTC) as the organic ligand, with a metal salt to organic ligand molar ratio of 3:1; Dissolve the metal salt in 45 mL formic acid (as a regulator) and sonicate for 30 min to obtain the metal ion source solution; Dissolve the organic ligand in 45 mL formic acid... An organic ligand solution was obtained by sonication in N,N-dimethylformamide (DMF) (as solvent) for 30 min. Subsequently, the metal ion source solution, organic ligand solution, and 4,4-azobenzene dicarboxylic acid ligand were mixed in a reaction vessel and reacted at 120 °C for 24 h. After the reaction, the mixture was allowed to cool naturally to room temperature, and the solid product was obtained by centrifugation. The solid product was washed twice with DMF and methanol, respectively, and finally dried at 70 °C for 12 h to obtain AZO2-MOF-808 material. The amount of 4,4-azobenzene dicarboxylic acid ligand added was 0.05 g relative to 1 g of metal-organic framework material; methanol was used as the organic solvent; the sonication frequency was 30 kHz; and the content of the metal-organic framework raw material in the suspension was 5 mg / mL. S1. Under continuous stirring and in an air atmosphere at 25°C, the suspension containing the metal-organic framework raw material was subjected to ultraviolet irradiation for 30 minutes to obtain the photo-irradiated product; wherein, the ultraviolet irradiation wavelength was 365nm, the light power was 10mW, and the stirring speed was 500rpm. S2. The photo-irradiated product was separated into solid and liquid phases by centrifugation to obtain a solid phase product. The solid phase product was washed three times with fresh methanol and then dried to obtain a metal-organic framework material (LS-AZO2-MOF-808). Each wash involved adding 20 mL of methanol and ultrasonically dispersing the product at 30 kHz, followed by centrifugation at 10,000 rpm for 5 min. The drying process was carried out at 60 ℃ for 6 h.

[0058] Example 2 The method in Example 1 is used, but the difference from Example 1 is that in step S0, the amount of 4,4-azobenzene dicarboxylic acid ligand added is 0.6g relative to 1g of metal-organic framework material, and the metal-organic framework raw material prepared is denoted as AZO1-MOF-808.

[0059] Example 3 The method in Example 1 is used, but the difference from Example 1 is that in step S0, the amount of 4,4-azobenzene dicarboxylic acid ligand added is 0.1g relative to 1g of metal-organic framework material, and the metal-organic framework raw material prepared is denoted as AZO3-MOF-808.

[0060] Example 4 The method in Example 1 is used, but the difference from Example 1 is that in step S0, the amount of 4,4-azobenzene dicarboxylic acid ligand added is 0.15g relative to 1g of metal-organic framework material, and the metal-organic framework raw material prepared is denoted as AZO4-MOF-808.

[0061] Example 5 The method described in Example 1 differs from that in step S0, where the metal-organic framework raw material is MOF-808. MOF-808 is prepared using a laboratory solvothermal method. Specifically, the following feed amounts are used: 1.05 g (4.5 mmol) of ZrCl4 (zirconium tetrachloride) is weighed as the metal ion source, and 0.31 g (1.5 mmol) of trimesic acid (H3BTC) is used as the organic ligand, with a metal salt to organic ligand molar ratio of 3:1. The metal salt is dissolved in 45 mL of formic acid (as a modifier) ​​and sonicated for 30 min to obtain the metal ion source solution. The organic ligand is dissolved in 45 mL of N,N-dimethylformamide (DMF) (as a solvent) and sonicated for 30 min. The organic ligand solution was obtained by centrifugation. The metal ion source solution and the organic ligand solution were then mixed in a reaction vessel and reacted at 120°C for 24 hours. After the reaction, the mixture was allowed to cool naturally to room temperature, and the solid product was obtained by centrifugation. The solid product was washed twice with DMF and methanol, respectively, and finally dried at 70°C for 12 hours to obtain the MOF-808 material. The prepared metal-organic framework material is designated as LS-MOF-808.

[0062] Example 6 The method used in Example 1 differs from that in Example 1 in that: in step S1, the suspension containing the metal-organic framework raw material is subjected to ultraviolet irradiation for 20 minutes.

[0063] Example 7 The method used in Example 1 differs from that in Example 1 in that: in step S1, the suspension containing the metal-organic framework raw material is subjected to ultraviolet irradiation for 60 minutes.

[0064] Example 8 The method used in Example 1 differs from that in Example 1 in that: in step S1, the suspension containing the metal-organic framework raw material is subjected to ultraviolet irradiation treatment for 50 hours.

[0065] Example 9 The method described in Example 1 differs from that in Example 1 in that: in step S1, the suspension containing the metal-organic framework raw material is subjected to ultraviolet irradiation under continuous ultrasound; wherein, the frequency of ultrasound is 100 kHz.

[0066] Example 10 The method described in Example 1 is used, except that in step S1, the temperature of the ultraviolet irradiation treatment is 80°C.

[0067] Example 11 The method described in Example 1 is used, but differs from that in Example 1 in that: in step S0, the content of the metal-organic framework raw material in the suspension is 60 mg / mL; the amount of the metal-organic framework raw material used is 600 mg; and the amount of organic solvent used is 10 mL.

[0068] Example 12 The method described in Example 1 differs from that in Example 1 in that: in step S0, the metal-organic framework raw material is NH2-MIL-125(Ti) (derived from the laboratory synthesis of NH2-MIL-125(Ti): using the classic solvothermal method, specifically: weighing 2.86 g (15.8 mmol) of 2-aminoterephthalic acid (H2ATA) as the organic ligand, measuring 2.86 mL (9.7 mmol) of isopropyl titanate (Ti(OiPr)4, also known as tetraisopropoxide titanium) as the titanium metal source, and dissolving it in 40 mL of... The mixture was prepared in a solvent of N,N-dimethylformamide (DMF) and 10 mL of anhydrous methanol (MeOH). The solution was then transferred to a PTFE-lined stainless steel high-pressure reactor, sealed, and placed in an oven for heating. The reaction temperature was typically controlled at 120°C for 72 hours. After the reaction, the mixture was allowed to cool naturally to room temperature and centrifuged to obtain a yellow solid product. This solid product was then washed 2-3 times with DMF and methanol to remove unreacted raw materials and solvent molecules from the pores. Finally, the washed product was dried and activated at a temperature between room temperature and 100°C to obtain NH2-MIL-125(Ti) material. The organic solvent was N,N-dimethylformamide (DMF). In step S1, the wavelength of the ultraviolet irradiation treatment was 360 nm.

[0069] Example 13 The method described in Example 1 is used, except that the metal-organic framework material is replaced with UiO-66.

[0070] Comparative Example 1 The method described in Example 1 is different from that in Example 1 in that: in step S0, the metal-organic framework raw material is MIL-101; wherein, the preparation method of MIL-101 includes: dissolving FeCl3·6H2O and terephthalic acid in N,N-dimethylformamide (DMF), and then reacting at 110°C for 20 h to obtain MIL-101.

[0071] Comparative Example 2 The method described in Example 1 differs from that in Example 1 in that, in step S1, a laser with a wavelength of 532 nm is used to irradiate the suspension containing the metal-organic framework raw material, with a power of 3 W.

[0072] Comparative Example 3 The method described in Example 1 differs from that in Example 1 in that, in step S1, a laser with a wavelength of 1064 nm is used to irradiate the suspension containing the metal-organic framework raw material, with a power of 10 W.

[0073] Comparative Example 4 The method described in Example 1 is used, except that the metal-organic framework material is replaced with zeolite.

[0074] Comparative Example 5 The method described in Example 1 is used, except that the metal-organic framework material is replaced with biochar.

[0075] Test case The metal-organic framework materials provided in Examples 1 and 5 were subjected to XRD tests using an X-ray diffractometer (Bruker D8 ADVANCE). The test results are as follows: Figure 1 As shown; The metal-organic framework raw materials provided in Examples 1-5 and the metal-organic framework adsorbent material prepared in Example 1 were subjected to scanning electron microscopy (SEM) using a Hitachi S-4800 SEM and a JEOL JEM-2100F SEM. The metal-organic framework raw materials and metal-organic framework adsorbent materials provided in Examples 1 and 5 were subjected to transmission electron microscopy (TEM). The test results are as follows: Figure 2 , Figure 3 , Figure 4 As shown; X-ray photoelectron spectroscopy (XPS) was used to test the metal-organic framework raw materials and metal-organic framework adsorbents provided in Examples 1 and 5, and the test results are as follows. Figure 5 andFigure 6 As shown; Figures 1-4 It can be seen that the XRD, SEM, and TEM images of the metal-organic framework raw materials before and after ultraviolet light treatment did not show significant changes, indicating that the material structure remained stable under ultraviolet light treatment and did not collapse. Figure 5 It can be seen that the XPS spectra of AZO2-MOF-808 and MOF-808 did not change significantly before and after ultraviolet light treatment, indicating that the structure of the material is stable under ultraviolet light treatment, further proving that the method provided in this application can effectively maintain the integrity of crystal structure and morphology.

[0076] Under the reaction conditions of room temperature (25℃), initial tetracycline concentration of 20 mg / L, adsorbent dosage of 0.1 g / L, and solution pH of 6 ± 0.01, the metal-organic framework adsorbents prepared in Examples 1-10 and Comparative Examples 1-5 were used to conduct adsorption tests on tetracycline. The test results are shown in Table 1.

[0077] Table 1

[0078] From the data in Table 1 and Figures 1-6 It is understood that the metal-organic framework adsorbent material provided by the present invention effectively maintains the crystal structure and morphology of MOFs materials and avoids framework collapse; on the other hand, the material has more open metal sites and active adsorption sites, which effectively improves the adsorption performance of the material, so that the adsorption efficiency of the metal-organic framework adsorbent materials provided in Examples 1-10 of this application for tetracycline is higher than that of Comparative Examples 1-5.

[0079] Comparing Example 1 and Example 2, it can be seen that Example 1 controls the amount of azo ligand and the irradiation dose within the preferred range of this application. The synergistic effect of the two produces a more suitable amount of cis isomer, which enables the metal-organic framework material to obtain a more suitable photoinduced defect concentration and a better unobstructed pore, further improving the adsorption efficiency of the prepared metal-organic framework adsorbent material for tetracycline. Therefore, it further verifies that the preparation method of this application is a synergistic system of doping amount and irradiation dose.

[0080] Comparing Example 1 with Example 5, it can be seen that, Figure 6 The O 1s peak fractionation results after illumination showed that the metal-organic framework adsorbent material prepared in Example 1 had an A 羟基 / A 晶格 The value is 0.66, while the A value of the metal-organic framework adsorbent in Example 5 is... 羟基 / A 晶格 It is 0.29, and at the same time by Figure 6As can be seen, compared to Example 5, the defect-related oxygen area at 531.0-532.0 eV decreased more significantly in Example 1 (from 0.66 to 0.52). This desorption of coordinated water or solvent molecules from the defect sites exposes more unsaturated metal sites, enabling the adsorption of more water molecules or hydroxyl species. Therefore, the increase in hydroxyl oxygen species (approximately 532.5-533.5 eV) in the adsorbent material obtained after UV irradiation of the AZO2-MOF-808 used in Example 1 is more pronounced (compared to Example 5, where MOF-808 was irradiated with UV light). The number of hydroxyl oxygen species in LS-MOF-808 obtained after UV irradiation of F-808 increased from 0.05 to 0.07, while the number of hydroxyl oxygen species in LS-AZO2-MOF-808 obtained after UV irradiation of AZO2-MOF-808 in Example 1 increased from 0.09 to 0.19. This indicates that the modification of azobenzene can significantly increase the photoinduced defect content of metal-organic framework materials, exposing more open metal sites and active adsorption sites, and further improving the adsorption efficiency of the material for tetracycline.

[0081] Comparing Example 1 and Example 8, it can be seen that controlling the ultraviolet treatment time within the preferred range of this application can achieve precise control of the irradiation dose, making the ratio of absorbance (A)... 430 / A 320 By controlling the process within a suitable range, the proportion of cis-azobenzene in the framework can be precisely controlled, ultimately achieving efficient and precise regulation of defect concentration. At the same time, a suitable processing time can also prevent photocorrosion of the MOF framework, ensuring unobstructed material pore structure and improved long-range order, thereby effectively enhancing the material's adsorption performance and further improving the adsorption efficiency of tetracycline.

[0082] Comparing Example 1 and Example 9, it can be seen that the stirring treatment can ensure the uniformity of light irradiation without damaging the material structure, effectively increasing the total number of effective active sites in a unit mass of material, thus further improving the adsorption performance.

[0083] Comparing Example 1 with Example 10, it can be seen that controlling the temperature within a suitable range can effectively suppress the thermal relaxation rotation of cis-azobenzene, maintain a high cis ratio and sufficient defective active sites; at the same time, it can prevent the MOF framework from undergoing structural degradation due to thermal stress, maintain the integrity of the channels; and in conjunction with the thermodynamic characteristics of the exothermic adsorption of tetracycline, it can shift the adsorption equilibrium in a favorable direction, thereby further improving the adsorption capacity and stability.

[0084] Comparing Example 1 with Example 11, it is evident that controlling the suspension concentration within a suitable range ensures that the UV light penetration depth matches the active material's bulk density, balancing sufficient light irradiation with material loading. At appropriate concentrations, UV light can penetrate deep into the suspension, providing equivalent irradiation to both internal and surface MOF particles. This allows for uniform azobenzene isomerization throughout the system, avoiding the uneven distribution of surface modification and unreacted internal components at high concentrations. This uniform and sufficient isomerization maximizes the defect concentration and the number of active sites, thus effectively improving the adsorption efficiency for tetracycline.

[0085] Comparing Comparative Example 1 with Example 1, it can be seen that since the MIL-101 used in Comparative Example 1 is an iron-based MOF, its iron-oxygen metal clusters are difficult to undergo efficient and controllable local structural reconstruction and lattice oxygen dissociation under ultraviolet irradiation, unlike the zirconium-oxygen clusters in Example 1. As a result, the number of open metal sites and active adsorption sites generated by photoinduced is much lower than that in Example 1, making its adsorption efficiency for tetracycline significantly worse than that in Example 1 of this application.

[0086] Comparing Comparative Examples 2 and 3 with Example 1, it can be seen that, since the metal-organic framework raw materials are irradiated with lasers of wavelengths not specified in this application, it is impossible to effectively induce local structural reconstruction of the metal clusters in the metal-organic framework raw materials, and it is impossible to effectively increase the content of photoinduced defects. As a result, the prepared adsorbent material does not have many open metal sites and active adsorption sites, and the adsorption performance is poor, so it cannot effectively adsorb tetracycline.

[0087] Comparing Comparative Examples 4 and 5 with Example 1, it can be seen that zeolite and biochar do not possess the highly ordered pore structure and tunable metal cluster nodes unique to metal-organic framework materials, and cannot generate controllable defects and open metal sites through ultraviolet light induction.

[0088] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0089] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0090] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A method for preparing metal-organic framework adsorbent materials, characterized in that, The method includes: S1. The suspension containing metal-organic framework raw materials is subjected to ultraviolet irradiation to obtain the photo-irradiated product. S2. Perform solid-liquid separation on the light-irradiated product to obtain a solid product; The wavelength of the ultraviolet irradiation treatment is 200-400nm; The metal-organic framework raw material includes metal-organic framework materials; the metal-organic framework materials include at least one of zirconium-based metal-organic framework materials, titanium-based metal-organic framework materials, zinc-based metal-organic framework materials, and copper-based metal-organic framework materials.

2. The method according to claim 1, characterized in that, The metal-organic framework material includes at least one of MOF-808, UiO-66, and Cu-BTC.

3. The method according to claim 1, characterized in that, The method satisfies at least one of the following conditions: The metal-organic framework raw material also includes metal-organic framework materials containing azophenyl groups; The method further includes: mixing the metal-organic framework material with a carboxylic acid compound containing an azo bond to obtain the metal-organic framework material containing an azophenyl group; The amount of carboxylic acid compounds containing azo bonds added is 0.01-0.5g relative to 1g of metal-organic framework material; The carboxylic acid compounds containing azo bonds include at least one of 4,4'-azobenzenediacarboxylic acid, 3,3'-azobenzenediacarboxylic acid, and 2,2'-azobenzenediacarboxylic acid.

4. The method according to claim 1, characterized in that, The method satisfies at least one of the following conditions: The ultraviolet irradiation treatment is carried out under stirring; the stirring speed is 50-2000 rpm; The ultraviolet irradiation treatment is performed under a first ultrasound; the frequency of the first ultrasound is 20-1000 kHz. The wavelength of the ultraviolet irradiation treatment is 300-370 nm; The optical power of the ultraviolet irradiation treatment is 2-100mW; The ultraviolet irradiation treatment is carried out at a temperature of 0-60℃ for a duration of 0.3-48h. The atmosphere for the ultraviolet irradiation treatment is air.

5. The method according to claim 1, characterized in that, The content of the metal-organic framework raw material in the suspension is 1-50 mg / mL.

6. The method according to claim 1, characterized in that, The method satisfies at least one of the following conditions: The method further includes: S0, mixing the metal-organic framework raw material with an organic solvent to obtain a suspension containing the metal-organic framework raw material; The mixing is performed under a second ultrasound; the frequency of the second ultrasound is 20-1000 kHz, and the duration is 5-120 min.

7. The method according to claim 6, characterized in that, The method satisfies at least one of the following conditions: The organic solvent includes at least one of water, alcohols, amines, ketones, and amides having 1-4 carbon atoms; The organic solvent includes at least one of water, methanol, ethanol, isopropanol, N,N-dimethylformamide, and acetone.

8. The method according to claim 1, characterized in that, The method further includes: washing and drying the solid product; The drying conditions include a temperature of 60-150℃ and a time of 3-24h.

9. A metal-organic framework adsorbent material prepared by the method according to any one of claims 1-8; in, A in the ultraviolet-visible absorption spectrum of the metal-organic framework adsorbent 430 / A 320 It is 0.64-0.8; Among them, A 320 This refers to the absorbance at 320 nm in the ultraviolet-visible absorption spectrum of the metal-organic framework adsorbent material; A 430 This refers to the absorbance at 430 nm in the ultraviolet-visible absorption spectrum of the metal-organic framework adsorbent material; and / or, A in the XPS O1s spectrum of the metal-organic framework adsorbent material 羟基 / A 晶格 It is 0.2-0.7; where A 晶格 This refers to the peak area of ​​the lattice oxygen characteristic peak in the XPS O1s spectrum of the metal-organic framework adsorbent; A 羟基 It refers to the peak area of ​​the characteristic hydroxyl oxygen peak in the XPS O1s spectrum of the metal-organic framework adsorbent material.

10. The metal-organic framework adsorbent material of claim 9 is used to adsorb antibiotics.

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