Functionalized MOFs material, preparation method and application thereof

Abstract

The application discloses a kind of functional MOFs materials and preparation method and application, belong to metal organic framework modified adsorption material technical field.The functional MOFs material is with glutaraldehyde as crosslinking agent, 2-amino-5-mercapto-1, 3, 4-thiadiazole and MIL-101-NH2 are covalently bonded graft modification and obtained metal organic framework adsorption material by Schiff base reaction.It has the excellent performance of fast adsorption rate and high removal efficiency to low concentration Pd (II), especially suitable for 1-5mg / L order low concentration palladium-containing wastewater purification treatment, and can reach industry discharge standard (0.02~0.05 mg / L).The preparation process of the application is simple, the reaction condition is mild, the modification controllability is strong, and it is consistent with the sustainable development concept of green chemical industry and precious metal resource recovery, and has good industrialization application prospect in the field of low concentration Pd (II) industrial wastewater and environmental water treatment.

Description

Technical Field

[0001] This invention belongs to the technical field of metal-organic framework modified adsorbent materials, and particularly relates to a functionalized MOF material, its preparation method and application. Background Technology

[0002] Currently, the main methods for treating Pd(II)-containing wastewater include solvent extraction, ion exchange, membrane separation, and adsorption. Among these, adsorption technology has become the preferred solution for the recovery and deep removal of low-concentration palladium due to its high selectivity, fast adsorption kinetics, ability to recover precious metals, environmental friendliness, and suitability for strongly acidic systems.

[0003] Metal-organic frameworks (MOFs) have shown great promise for the efficient capture of Pd(II) due to their high specific surface area, tunable pore structure, and easily modifiable functional sites. However, unmodified MOFs generally suffer from insufficient active sites, poor stability under acidic conditions, and difficulty in balancing selectivity and adsorption rate for Pd(II), making it difficult to meet the practical needs of rapid, deep, and efficient recovery of low-concentration Pd(II) from industrial wastewater.

[0004] Patent CN119285031A discloses a method for amylation modification using 3-amino-trimethoxysilane to prepare an aminated gelatin solution, which is then combined with a modified metal-organic framework material and modified nitrogen-containing biochar to obtain an adsorbent with good adsorption performance for nickel and cadmium ions. However, this material has not undergone acid resistance modification or pore structure optimization, resulting in slow adsorption kinetics and poor enrichment efficiency in low-concentration ion systems. Patent CN121819790A discloses an adsorbent material based on a core-shell substrate, chitosan, and polyethyleneimine synergistic effect, exhibiting excellent adsorption performance for palladium and platinum in acidic wastewater. However, this material has not been tested for removal performance in low-concentration Pd(II) wastewater, making it difficult to meet the requirements for efficient treatment and resource recovery of low-concentration industrial acidic palladium-containing wastewater.

[0005] Therefore, it is urgent to develop modification strategies based on ligand-functionalized MOFs to improve their adsorption performance for Pd(II) in low-concentration systems, thereby achieving efficient resource utilization of the precious metal palladium and deep purification of palladium-containing wastewater. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention proposes a functionalized MOF material, its preparation method, and its application, in order to solve the problems of poor water stability, insufficient acid resistance, and slow palladium ion adsorption rate caused by the lack of specific adsorption sites in existing MOF adsorbent materials.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] One objective is to develop a functionalized MOF material, wherein the functionalized MOF material is a metal-organic framework adsorbent material (MIL-MTDx) obtained by covalently grafting 2-amino-5-mercapto-1,3,4-thiadiazole (MTD) with MIL-101-NH2 via a Schiff base reaction using glutaraldehyde as a crosslinking agent.

[0009] This invention uses glutaraldehyde as a linker and MTD as a modifying molecule to prepare a thiol-rich metal-organic framework through a two-step modification process. MTD containing thiol and amino groups is then grafted onto the surface of the metal-organic framework to obtain a modified metal-organic framework adsorbent. MIL-MTD, with its structural advantages of being rich in amino and thiol active sites, exhibits excellent performance in terms of fast adsorption rate and high removal efficiency for low concentrations of Pd(II), making it particularly suitable for the purification treatment of low-concentration palladium-containing wastewater at the 5 mg / L level.

[0010] Further, the molar ratio of MIL-101-NH2, glutaraldehyde and 2-amino-5-mercapto-1,3,4-thiadiazole is 1:(12~40):(1.2~4).

[0011] Objective 2: A method for preparing functionalized MOF materials, comprising the following steps:

[0012] (1) Disperse MIL-101-NH2 in N,N-dimethylformamide (DMF), add glutaraldehyde to the resulting mixed solution, and stir at room temperature to obtain glutaraldehyde-grafted modified metal-organic framework material;

[0013] (2) Under nitrogen protection, 2-amino-5-mercapto-1,3,4-thiadiazole was added to the glutaraldehyde-grafted modified metal-organic framework material, heated and stirred, filtered, washed and dried to obtain the functionalized MOF material.

[0014] Furthermore, in step (1), the stirring time at room temperature is 24 hours. Under this condition, the amino groups on the MOF surface can react fully, thereby ensuring the efficient grafting of glutaraldehyde and providing a good foundation for the subsequent modification reaction at the other end.

[0015] Furthermore, the heating and stirring temperature is 20~90℃, and the time is 24h.

[0016] Furthermore, the reagent used for washing is selected from at least two of deionized water, N,N-dimethylformamide, and ethanol.

[0017] Furthermore, the drying temperature is 60°C and the time is 12 hours.

[0018] Third objective: Application of a functionalized MOF material in the adsorption of Pd(II) in wastewater.

[0019] Furthermore, the concentration of Pd(II) in the wastewater is 1~200 mg / L.

[0020] Furthermore, during the adsorption process, the solid-liquid ratio of the functionalized MOFs material to the wastewater is (10~25) mg: (45~50) mL.

[0021] Furthermore, the adsorption time is 30 min to 12 h.

[0022] Compared with the prior art, the present invention has the following advantages and technical effects:

[0023] (1) This invention uses MIL-101-NH2 as raw material and modifies it with glutaraldehyde and MTD via Schiff base modification to prepare a metal-organic framework adsorbent containing thiol groups. This material exhibits good adsorption performance for low-concentration palladium waste liquid. The modified adsorbent material not only retains the original amino functional groups but also introduces abundant thiol active sites, and it has good dispersibility in acidic waste liquid, thus significantly improving the adsorption effect.

[0024] (2) The core feature of the MTD-modified MIL-101-NH2 material provided by this invention is that the modification significantly improves the water stability and acid resistance of the material, while retaining the advantages of the pore structure of the matrix material. MTD combines with MIL-101-NH2 through cross-linking grafting to form a stable chemical bond structure, effectively inhibiting the collapse and dissolution of the material's skeleton in aqueous solution, ensuring its structural integrity and stable performance during long-term aqueous phase adsorption. In terms of acid resistance, the modified material can exist stably in strongly acidic systems with pH≥1, overcoming the defects of poor acid resistance and large dissolution under acidic conditions of unmodified MIL-101-NH2. In addition, the grafting of MTD does not block the original microporous-mesoporous structure of the material, retaining sufficient adsorption active sites, taking into account both adsorption capacity and adsorption kinetics performance, and is suitable for the efficient adsorption of low concentrations of Pd(II). This material is highly practical and can be widely used in the treatment of acidic Pd(II)-containing wastewater.

[0025] (3) The product of this invention can rapidly remove Pd(II) ions under low concentration conditions and meet the emission standards stipulated by the industry. Therefore, this invention can be effectively applied to the pollution treatment of palladium-containing wastewater, significantly reducing the harm of palladium pollution to the natural environment. In addition, the MTD modified metal-organic framework adsorbent provided by this invention has the advantages of simple preparation process, economic and environmental protection, and high adsorption capacity. It is not only suitable for the treatment of palladium-containing wastewater, but also can effectively alleviate the waste of precious metal resources and environmental pollution problems, which is in line with the current concept of green chemistry and sustainable development. Attached Figure Description

[0026] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0027] Figure 1 This is a schematic diagram illustrating the preparation principle of the functionalized MOFs material in this invention;

[0028] Figure 2 The adsorption capacity diagram of Pd(II) by the adsorbent under different modification ratios is shown.

[0029] Figure 3 SEM images of different adsorbents are shown; where (a) is MIL-101-NH2 and (b) is MIL-MTD. 20 (c) is MIL-MTD 30 (d) is MIL-MTD 90 ;

[0030] Figure 4 Graphs showing the elemental composition of adsorbents modified at different temperatures;

[0031] Figure 5 The graph shows the change in the adsorption capacity of the adsorbent for palladium ions over time under different temperature modifications.

[0032] Figure 6 MIL-MTD 30 The adsorption capacity of the adsorbent for a 10 mg / L Pd(II) solution as a function of time under three different solid-liquid ratios is shown in the graph.

[0033] Figure 7 MIL-MTD 30 The curves showing the change of adsorption capacity of the adsorbent for a 5 mg / L Pd(II) solution over time at three different solid-liquid ratios.

[0034] Figure 8 MIL-MTD 30 The adsorbent concentrations and removal rates of Pd(II) solutions with concentrations of 1, 2, 5, and 10 mg / L before and after adsorption for 30 min are compared. Detailed Implementation

[0035] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0036] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0037] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0038] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0039] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0040] The technical concept of this invention is as follows: This invention utilizes inexpensive glutaraldehyde and MTD as ligands for linkage. Its amino and thiol groups can serve as effective sites for palladium adsorption. Glutaraldehyde is used as a crosslinking agent, and the aldehyde groups at both ends enable the binding of MOF and MTD, increasing the surface area of ​​the material and forming a porous framework structure to provide channels for Pd transport. This increases the accessibility of the sites, thereby effectively achieving rapid capture and efficient adsorption of low-concentration Pd(II) (see schematic diagram). Figure 1 ).

[0041] This invention provides a method for preparing functionalized MOF materials, comprising the following steps:

[0042] (1) Take N,N-dimethylformamide (DMF) as the reaction solvent, add MIL-101-NH2 into the reaction apparatus, and ultrasonically disperse for 3-5 min to obtain a mixed solution; add glutaraldehyde dropwise to the mixed solution and stir at room temperature for 24 h to obtain the first step glutaraldehyde grafted modified metal-organic framework material (MIL-101-GD).

[0043] (2) In a nitrogen atmosphere, 2-amino-5-mercapto-1,3,4-thiadiazole (MTD) was added to the glutaraldehyde-grafted modified metal-organic framework material obtained in step (1), the temperature was raised to 20~90℃, and the mixture was stirred for 24h. After filtration, washing, and drying, the metal-organic framework adsorbent material modified with MTD (MIL-MTD) was obtained. x X represents different temperatures: 20℃, 30℃, 90℃).

[0044] In the following optional embodiments of the present invention, the molar ratio of MIL-101-NH2, glutaraldehyde, and 2-amino-5-mercapto-1,3,4-thiadiazole is 1:(12~40):(1.2~4). Preferably, the molar ratio is 1:12:1.2, 1:20:2, or 1:40:4, and more preferably 1:20:2.

[0045] In the following optional embodiments of the present invention, the washing reagent is selected from at least two of deionized water, N,N-dimethylformamide, and ethanol. Exemplarily, in the following preferred embodiments of the present invention, deionized water and N,N-dimethylformamide are used alternately to wash the sample.

[0046] In the following preferred embodiments of the present invention, the drying temperature is 60°C and the drying time is 12 hours.

[0047] A functionalized MOF material can be prepared using the above preparation method. It can be used in the field of adsorbing Pd(II) in wastewater. The specific method is as follows: according to the solid-liquid ratio of functionalized MOF material to wastewater of (10~25) mg: (45~50) mL (such as 25mg:50mL, 15mg:45mL or 10mg:50mL), the functionalized MOF material is added to Pd(II) containing wastewater with a concentration of 1~200mg / L (such as 5mg / L or 10mg / L) for adsorption treatment for 30min~12h to obtain the treated wastewater.

[0048] Unless otherwise specified, "room temperature" in this invention refers to 25°C.

[0049] All raw materials used in this invention were purchased from the market.

[0050] The technical solution of the present invention will be further illustrated by the following embodiments.

[0051] Example 1

[0052] A method for preparing functionalized MOF materials includes the following steps:

[0053] (1) Weigh 0.8g of MIL-101-NH2 and disperse it in a round-bottom flask containing 10mL of N,N-dimethylformamide (DMF). Sonicate for 4min to completely disperse the powder. Then add 1.199mL of glutaraldehyde to the resulting solution and stir at room temperature for 24h to obtain a uniform green solution (named MIL-101-GD).

[0054] (2) In a nitrogen atmosphere, 0.1696 g of 2-amino-5-mercapto-1,3,4-thiadiazole (MTD) was added to the green solution obtained in step (1) and stirred at room temperature for 24 h.

[0055] (3) After the reaction is complete, the product is washed twice with DMF and deionized water respectively. Finally, the solid product is filtered and dried under vacuum at 60°C for 12 hours to obtain a dry olive green powder, which is the functionalized MOF material (named MIL-MTD-①).

[0056] Example 2

[0057] A method for preparing functionalized MOF materials includes the following steps:

[0058] (1) Weigh 0.8g of MIL-101-NH2 and disperse it in a round-bottom flask containing 10mL of N,N-dimethylformamide (DMF). Sonicate for 4min to completely disperse the powder. Then add 1.999mL of glutaraldehyde to the resulting solution and stir at room temperature for 24h to obtain a uniform green solution (named MIL-101-GD).

[0059] (2) In a nitrogen atmosphere, 0.2826 g of 2-amino-5-mercapto-1,3,4-thiadiazole (MTD) was added to the green solution obtained in step (1) and stirred at room temperature for 24 h.

[0060] (3) After the reaction is complete, the product is washed twice with DMF and deionized water respectively. Finally, the solid product is filtered and dried under vacuum at 60°C for 12 hours to obtain a dry olive green powder, which is the functionalized MOF material (named MIL-MTD-②).

[0061] Example 3

[0062] A method for preparing functionalized MOF materials includes the following steps:

[0063] (1) Weigh 0.8g of MIL-101-NH2 and disperse it in a round-bottom flask containing 10mL of N,N-dimethylformamide (DMF). Sonicate for 4min to completely disperse the powder. Then add 3.9972mL of glutaraldehyde to the resulting solution and stir at room temperature for 24h to obtain a uniform green solution (named MIL-101-GD).

[0064] (2) In a nitrogen atmosphere, 0.5653 g of 2-amino-5-mercapto-1,3,4-thiadiazole (MTD) was added to the green solution obtained in step (1) and stirred at room temperature for 24 h.

[0065] (3) After the reaction is complete, the product is washed twice with DMF and deionized water respectively. Finally, the solid product is filtered and dried under vacuum at 60°C for 12 hours to obtain a dry olive green powder, which is the functionalized MOF material (named MIL-MTD-③).

[0066] Experimental Example 1

[0067] Adsorption experiment: Pd 2+ The solution was prepared by dissolving sodium tetrachloropalladium in ultrapure water. Sodium tetrachloropalladium was dissolved in 1 L of ultrapure water by ultrasonication to obtain a Pd concentration of 200 mg / L. 2+ Stock solution; determination of Pd in ​​water samples using continuous light source atomic absorption spectrometry. 2+ Concentrations were used to evaluate the effects of MIL-101-NH2, MIL-MTD-①, MIL-MTD-②, and MIL-MTD-③ on Pd. 2+ Adsorption effect.

[0068] The specific steps for verifying the adsorption capacity of functionalized MOFs materials with different addition ratios for palladium ions are as follows:

[0069] 20 mg of adsorbent (MIL-101-NH2, MIL-MTD-① of Example 1, MIL-MTD-② of Example 2, and MIL-MTD-③ of Example 3) was added to 50 mL of a 200 mg / L Pd(II) solution. The solution was placed in a water bath constant temperature shaker and shaken thoroughly at 25 °C and 180 rpm. After adsorption equilibrium was reached, a sample was taken and the Pd(II) concentration in the solution was determined using a flame atomic absorption spectrometer.

[0070] Figure 2The adsorption capacity diagrams for Pd(II) solutions with a concentration of 200 mg / L are shown for functionalized adsorbents obtained by MIL-101-NH2 and activation at different ratios. The results show that the adsorption effect on Pd(II) is optimal when the molar ratio of MIL-101-NH2, glutaraldehyde, and 2-amino-5-mercapto-1,3,4-thiadiazole is 1:20:2. That is, the adsorption capacity of MIL-MTD-② adsorbent for Pd(II) is significantly better than that of the unmodified adsorbent and the other ratios. Therefore, the temperature was investigated in subsequent activation under the same conditions as the synthesis ratio of MIL-MTD-② adsorbent.

[0071] Example 4

[0072] A method for preparing functionalized MOF materials includes the following steps:

[0073] (1) Weigh 0.8g of MIL-101-NH2 and disperse it in a round-bottom flask containing 10mL of N,N-dimethylformamide (DMF). Sonicate for 4min to completely disperse the powder. Then add 1.999mL of glutaraldehyde to the resulting solution and stir at room temperature for 24h to obtain a uniform green solution (named MIL-101-GD).

[0074] (2) In a nitrogen atmosphere, 0.2826 g of 2-amino-5-mercapto-1,3,4-thiadiazole (MTD) was added to the green solution obtained in step (1) and stirred at 20°C for 24 h.

[0075] (3) After the reaction was completed, the product was washed twice with DMF and deionized water respectively. Finally, the solid product was filtered and dried under vacuum at 60°C for 12 h to obtain a dry olive green powder, which is the functionalized MOF material (named MIL-MTD). 20 ).

[0076] Example 5

[0077] A method for preparing functionalized MOF materials includes the following steps:

[0078] (1) Weigh 0.8g of MIL-101-NH2 and disperse it in a round-bottom flask containing 10mL of N,N-dimethylformamide (DMF). Sonicate for 4min to completely disperse the powder. Then add 1.999mL of glutaraldehyde to the resulting solution and stir at room temperature for 24h to obtain a uniform green solution (named MIL-101-GD).

[0079] (2) In a nitrogen atmosphere, 0.2826 g of 2-amino-5-mercapto-1,3,4-thiadiazole (MTD) was added to the green solution obtained in step (1) and stirred at 30°C for 24 h.

[0080] (3) After the reaction was completed, the product was washed twice with DMF and deionized water respectively. Finally, the solid product was filtered and dried under vacuum at 60°C for 12 h to obtain a dry olive green powder, which is the functionalized MOF material (named MIL-MTD). 30 ).

[0081] Example 6

[0082] A method for preparing functionalized MOF materials includes the following steps:

[0083] (1) Weigh 0.8g of MIL-101-NH2 and disperse it in a round-bottom flask containing 10mL of N,N-dimethylformamide (DMF). Sonicate for 4min to completely disperse the powder. Then add 1.999mL of glutaraldehyde to the resulting solution and stir at room temperature for 24h to obtain a uniform green solution (named MIL-101-GD).

[0084] (2) In a nitrogen atmosphere, 0.2826 g of 2-amino-5-mercapto-1,3,4-thiadiazole (MTD) was added to the green solution obtained in step (1) and stirred at 90 °C for 24 h.

[0085] (3) After the reaction was completed, the product was washed twice with DMF and deionized water respectively. Finally, the solid product was filtered and dried under vacuum at 60°C for 12 h to obtain a dry olive green powder, which is the functionalized MOF material (named MIL-MTD). 90 ).

[0086] For MIL-101-NH2 and MIL-MTD x The following characteristics are used:

[0087] 1. SEM Analysis

[0088] The MIL-101-NH2 from Example 1 and the MIL-MTD from Example 4 were used. 20 MIL-MTD in Example 5 30 MIL-MTD in Example 6 90 The sample was blown onto conductive adhesive using a syringe, then adhered to the SEM sample stage. The sample was subsequently sputtered with gold to prevent surface charge buildup from affecting image quality. After being transferred to the sample chamber and evacuated, it was ion-sputtered for 30 seconds. The sample was then imaged using a JSM-7800F Prime SEM at magnifications ranging from 25 to 1,000,000 times. The results are as follows: Figure 3 As shown.

[0089] from Figure 3As can be seen, the unmodified MIL-101-NH2 exhibits an octahedral morphology, with clusters forming between particles; the MIL-MTD obtained after modification at different temperatures (20℃, 30℃, 90℃) x The material's crystal morphology is basically consistent with that of the original MIL-101-NH2, and it still maintains an octahedral structure, indicating that the modification process did not destroy the original morphological characteristics of the material.

[0090] 2. Elemental content analysis

[0091] The MIL-101-NH2 from Example 1 and the MIL-MTD from Example 4 were used. 20 MIL-MTD in Example 5 30 MIL-MTD in Example 6 90 The sample was placed in the Elementar UNICUBE elemental analyzer, and the sample mass was entered into its test program. High-temperature pyrolysis at 1150℃ was used to obtain the content percentage of each element. The results are as follows: Figure 4 As shown.

[0092] Figure 4 Elemental analysis results showed that unmodified MIL-101-NH2 contained no sulfur and only a small amount of nitrogen; however, after MTD modification, the sulfur and nitrogen contents in the material increased significantly, confirming that MTD (containing -SH) had been successfully grafted onto the material. Specifically, MIL-MTD prepared at 30℃... 30 The highest sulfur content indicates that it has the most abundant thiol active sites on its surface, which is more conducive to the efficient adsorption of Pd(II).

[0093] Experimental Example 2:

[0094] The applications of functionalized MOF materials that adsorb palladium at low concentrations are as follows:

[0095] Adsorption experiment: Pd 2+ The solution was prepared by dissolving sodium tetrachloropalladium in ultrapure water. Sodium tetrachloropalladium was dissolved in 1 L of ultrapure water by ultrasonication to obtain a Pd concentration of 200 mg / L. 2+ Stock solutions; dilute a 200 mg / L stock solution with deionized water to obtain different concentrations of Pd. 2+ Solution. Pd in ​​water samples was determined using a continuous-light source atomic absorption spectrometer. 2+ Concentrations used to evaluate MIL-101-NH2 and MIL-MTD x For Pd 2+ The adsorption effect was observed. The adsorption rate of palladium ions by functionalized MOFs materials at different temperatures was verified through the following steps:

[0096] Preliminary exploration of adsorption kinetics: 20 mg of adsorbent (MIL-101-NH2 and MIL-MTD from Example 4) were used. 20 MIL-MTD in Example 5 30 MIL-MTD in Example 6 90 Add to 50 mL of Pd solution with a concentration of 200 mg / L 2+ The solution was placed in a water bath at 35°C and 180 rpm and shaken thoroughly. Samples were taken at 0 min, 10 min, 30 min, 60 min, 90 min, 120 min, 360 min, and 720 min. The samples were filtered through a 0.45 μm polyethersulfone membrane to obtain the supernatant, and the Pd content in the solution after adsorption was determined by flame atomic absorption spectrometry (FAAS). 2+ Concentration changes.

[0097] Figure 5 The graphs show the adsorption capacity of different adsorbents for palladium ions over time. The results indicate that the functionalized MOFs materials prepared in Examples 4-6 have a maximum adsorption capacity Q for palladium ions. max It is 491.5 mg / g.

[0098] Experimental Example 3:

[0099] Verification of the MIL-MTD prepared in Example 5 30 The removal efficiency of the adsorbent on a 10 mg / L Pd(II) solution was investigated using the following steps:

[0100] (1) Prepare an aqueous solution of sodium tetrachloropalladium with a Pd(II) concentration of 10 mg / L and adjust the pH of the solution to 3;

[0101] (2) Weigh 10mg, 15mg and 25mg of MIL-MTD respectively. 30 The adsorbent was then used to measure 50 mL, 45 mL, and 50 mL of a 10 mg / L sodium tetrachloropalladium aqueous solution into 100 mL Erlenmeyer flasks. The flasks were then paired up to set solid-liquid ratios of 1 / 2 (25 mg: 50 mL), 1 / 3 (15 mg: 45 mL), and 1 / 5 (10 mg: 50 mL). The flasks were placed in a water bath at 35 °C and 180 rpm and shaken thoroughly. Samples were taken at 0 min, 5 min, 10 min, 20 min, 30 min, 60 min, 90 min, 240 min, and 360 min. The concentration of Pd(II) in the solution was determined using a flame atomic absorption spectrometer.

[0102] Figure 6 MIL-MTD 30The graphs show the adsorption capacity of the adsorbent for a 10 mg / L Pd(II) solution over time at three different solid-liquid ratios. The results indicate that at a solid-liquid ratio of 1 / 2, MIL-MTD... 30 The adsorbent can achieve a removal rate of up to 92% for palladium ions, but when the solid-liquid ratio is 1 / 3, MIL-MTD... 30 The adsorbent can quickly reach equilibrium for the removal of palladium ions within 5 minutes, and the removal rate is maintained at 89%.

[0103] Experimental Example 4:

[0104] Proof of MIL-MTD 30 The removal efficiency of the adsorbent on a 5 mg / L Pd(II) solution was investigated using the following steps:

[0105] (1) Prepare an aqueous solution of sodium tetrachloropalladium with a Pd(II) concentration of 5 mg / L and adjust the pH of the solution to 3;

[0106] (2) Weigh 10mg, 15mg and 25mg of MIL-MTD respectively. 30 The adsorbent was then used to prepare 50 mL, 45 mL, and 50 mL of a 5 mg / L sodium tetrachloropalladium aqueous solution, which were then placed in 100 mL Erlenmeyer flasks. These flasks were paired to achieve solid-liquid ratios of 1 / 2 (25 mg: 50 mL), 1 / 3 (15 mg: 45 mL), and 1 / 5 (10 mg: 50 mL). The flasks were placed in a water bath at 35°C and 180 rpm, and samples were taken at 0 min, 5 min, 10 min, 20 min, 30 min, 60 min, 90 min, 240 min, and 360 min. The Pd(II) concentration in the solution was determined using flame atomic absorption spectrometry.

[0107] Figure 7 MIL-MTD 30 The graphs show the adsorption capacity of the adsorbent for a 5 mg / L Pd(II) solution over time at three different solid-liquid ratios. The results indicate that, at the three solid-liquid ratios, MIL-MTD... 30 The adsorbents all reached equilibrium rapidly within 20 minutes, with a removal rate of 100%.

[0108] The above experiments show that when the solid-liquid ratio is too low (1 / 5), the adsorption will be insufficient due to insufficient adsorption sites and low ion contact probability; when the solid-liquid ratio is too high (1 / 2), the unit adsorption capacity will be low due to insufficient total metal ions, particle agglomeration, and wasted adsorption sites.

[0109] Experimental Example 5:

[0110] Proof of MIL-MTD 30The removal efficiency of the adsorbent on Pd(II) solutions with concentrations of 1, 2, 5, and 10 mg / L was investigated using the following steps:

[0111] (1) Prepare aqueous solutions of sodium tetrachloropalladium with Pd(II) concentrations of 1, 2, 5, and 10 mg / L, and adjust the pH of the solution to 3;

[0112] (2) Weigh 15 mg of MIL-MTD 30 The adsorbent was then added to 45 mL of sodium tetrachloropalladium aqueous solutions with concentrations of 1, 2, 5, and 10 mg / L, each in a 100 mL Erlenmeyer flask. The flasks were placed in a water bath at 35°C and 180 rpm, and shaken thoroughly. Samples were taken after 30 minutes, and the Pd(II) concentration in the solutions was determined using inductively coupled plasma atomic emission spectrometry (ICP-AES).

[0113] Figure 8 MIL-MTD 30 The adsorbent concentrations before and after adsorption of Pd(II) solutions at concentrations of 1, 2, 5, and 10 mg / L were compared, and the removal rates were plotted after 30 min of adsorption. The results showed that at low concentrations (1, 2, and 5 mg / L), MIL-MTD... 30 The adsorbent achieves a removal rate of nearly 100% within 30 minutes, meeting the industry's emission standards for palladium waste liquid.

[0114] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A functionalized MOFs material, characterized in that, The functionalized MOFs material is a metal-organic framework adsorbent material obtained by covalently grafting 2-amino-5-mercapto-1,3,4-thiadiazole with MIL-101-NH2 via Schiff base reaction using glutaraldehyde as a crosslinking agent.

2. The functionalized MOFs material according to claim 1, characterized in that, The molar ratio of MIL-101-NH2, glutaraldehyde and 2-amino-5-mercapto-1,3,4-thiadiazole is 1:(12~40):(1.2~4).

3. A method for preparing a functionalized MOF material as described in any one of claims 1 to 2, characterized in that, Includes the following steps: (1) Disperse MIL-101-NH2 in N,N-dimethylformamide, add glutaraldehyde to the resulting mixed solution, stir at room temperature to obtain glutaraldehyde-grafted modified metal-organic framework material; (2) Under nitrogen protection, 2-amino-5-mercapto-1,3,4-thiadiazole was added to the glutaraldehyde-grafted modified metal-organic framework material, heated and stirred, filtered, washed and dried to obtain the functionalized MOF material.

4. The preparation method according to claim 3, characterized in that, The heating and stirring temperature is 20~90℃, and the time is 24h.

5. The preparation method according to claim 3, characterized in that, The reagents used for washing are selected from at least two of deionized water, N,N-dimethylformamide, and ethanol.

6. The preparation method according to claim 3, characterized in that, The drying temperature is 60°C and the time is 12 hours.

7. The application of a functionalized MOF material as described in any one of claims 1 to 2 in the adsorption of Pd(II) wastewater.

8. The application according to claim 7, characterized in that, The concentration of Pd(II) in the wastewater is 1~200 mg / L.

9. The application according to claim 7, characterized in that, During the adsorption process, the solid-liquid ratio of the functionalized MOFs material to the wastewater is (10~25) mg: (45~50) mL.

10. The application according to claim 7, characterized in that, The adsorption time is 30 min to 12 h.

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