A metal organic framework adsorption material and its preparation method and application

Abstract

The present invention relates to the technical field of adsorbent material preparation, and specifically to a metal organic framework adsorption material, a preparation method thereof, and an application thereof. The preparation method comprises the following steps: in an organic solvent, using a soluble bismuth salt as a metal source and trimesic acid as a connecting ligand, a metal organic framework adsorption material with specific pocket-type capture channels is prepared by a solvent thermal reaction. The present invention develops a metal organic framework adsorption material with a high proportion of open sites for Sb(OH)6 in water based on the inherent structural properties of the material itself. ‑ Targeted capture to achieve a dual improvement in adsorption capacity and selectivity.

Description

Technical Field

[0001] The present invention relates to the technical field of adsorbent material preparation, and in particular to a metal organic framework adsorption material and a preparation method and application thereof. Background Art

[0002] Excessive mining and smelting of antimony ore have resulted in the release of large amounts of antimony into the water environment, with concentrations reaching as high as 1,330 to 7,000 μg / L. The "Sanitary Standards for Drinking Water" clearly stipulate that the concentration of antimony in drinking water must not exceed 5 μg / L. These antimony-containing wastewaters not only threaten human life and safety but also result in a significant waste of resources. Therefore, effective removal of antimony from wastewater is essential.

[0003] Antimony in water is mainly present as pentavalent oxygen-containing anions Sb(OH) 6- Precipitation methods, which have been used in a variety of forms, dominated the early stages of antimony removal from water. They offer advantages such as simplicity and ease of operation. However, the extensive use of precipitants and the sediment treatment process are typically high-carbon and energy-intensive, and a single technical approach cannot completely remove antimony. In comparison, ion exchange methods offer higher and faster removal efficiencies, but ion resins are expensive and easily oxidized and reduced, making them ineffective and difficult to universally apply. Adsorption, due to its simplicity, environmental friendliness, and high efficiency, is currently an effective and feasible method for treating antimony-containing heavy metal wastewater.

[0004] To achieve resource recovery of heavy metals, it is necessary to solve the problem of high capacity and selectivity of adsorption materials. Commonly used adsorbents reported so far include activated carbon, zeolite, and metal oxides, but they generally have low specific surface area, small pore volume, and few active functional groups, resulting in low adsorption capacity and poor selectivity.

[0005] Existing methods for preparing adsorbents to improve adsorption capacity mainly focus on increasing the specific surface area and modifying different functional groups. However, increasing the specific surface area makes it difficult to improve the adsorption capacity, while modifying different functional groups sharply reduces the selectivity of the material and cannot ensure complete access to effective sites. Summary of the Invention

[0006] In view of the deficiencies of the above-mentioned prior art, the purpose of the present invention is to provide a metal-organic framework adsorption material, a preparation method and application thereof. The present invention uses a soluble bismuth salt as a metal source and trimesic acid as a connecting ligand to prepare a metal-organic framework adsorption material with specific pocket-type capture channels through a solvent thermal reaction.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0008] A method for preparing a metal organic framework adsorption material comprises the following steps:

[0009] In an organic solvent, a metal-organic framework adsorption material with specific pocket-type capture channels was prepared by solvothermal reaction using soluble bismuth salt as the metal source and trimesic acid as the connecting ligand.

[0010] The present invention uses soluble bismuth salt as metal source and trimesic acid as connecting ligand to prepare metal organic framework adsorption material with specific pocket capture channels through solvent thermal reaction. The porous organic framework adsorbent formed by the present invention has high charge density of cationic Bi 3+ The high coordination number and flexible coordination mode of the metal organic framework adsorption material have the characteristics of matching Sb(OH) 6- The pore structure is large and favorable for Sb(OH) 6- The metal organic framework adsorption material with open pocket capture channels is developed based on the inherent structural properties of the material itself to form Bi-O-Sb bonds at the active sites of the adsorption material for selective capture of Sb(OH) in water. 6- Targeted capture to achieve a dual improvement in adsorption capacity and selectivity.

[0011] In a preferred embodiment of the present invention, the mass ratio of the soluble bismuth salt to trimesic acid is 1:1-5.

[0012] In a preferred embodiment of the present invention, the solvent thermal reaction temperature is 120° C. to 200° C., and the reaction time is 12 h to 72 h.

[0013] In a preferred embodiment of the present invention, the organic solvent is a mixed solvent of N,N-dimethylformamide and methanol.

[0014] In a preferred embodiment of the present invention, the volume ratio of N,N-dimethylformamide to methanol in the mixed solvent is 1 to 4:1.

[0015] In a preferred embodiment of the present invention, the soluble bismuth salt is Bi(NO 3 ) 3 ·5H 2 O.

[0016] Another object of the present invention is to provide a metal organic framework adsorption material prepared by any of the preparation methods described above.

[0017] In a preferred embodiment of the present invention, the metal organic framework adsorption material is a hexagonal rod-shaped structure.

[0018] The third object of the present invention is to provide a metal organic framework adsorption material as described above for efficiently and selectively capturing Sb(OH) in antimony-containing wastewater. 6- Application in.

[0019] In a preferred embodiment of the present invention, the concentration of antimony-containing wastewater is 50 mg / L to 2000 mg / L, and the usage ratio of the metal organic framework adsorption material to the antimony-containing wastewater is 1 mg:1 mL to 4 mL.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The present invention uses soluble bismuth salt as metal source and trimesic acid as connecting ligand to prepare metal organic framework adsorption material with specific pocket capture channels through solvent thermal reaction. The porous organic framework adsorbent formed by the method of the present invention has high charge density of cationic Bi 3+ The high coordination number and flexible coordination mode of the metal organic framework adsorption material have the characteristics of matching Sb(OH) 6- The pore structure is large and favorable for Sb(OH) 6- The metal organic framework adsorbent is developed based on the inherent structural properties of the material itself to develop a pocket-type capture channel metal organic framework adsorbent with a high proportion of open sites for Sb(OH) in water. 6- Targeted capture to achieve a dual improvement in adsorption capacity and selectivity.

[0022] 2. The good adsorption performance of the metal organic framework adsorption material prepared by the present invention is mainly due to the following reasons: ① The metal organic framework adsorption material has a large specific surface area, which can provide sufficient adsorption sites; ② The large number of pores inside the material provide sufficient transmission channels, which is conducive to the adsorption of Sb(OH) 6- Mass transfer rate increases the accessibility of active sites, resulting in increased adsorption capacity; ③ Open pores and Sb(OH)6 - The size is appropriately matched and selectively captured by forming Bi-O-Sb bonds. Based on this, this high affinity for Sb(OH) 6- The distribution coefficient reaches 1.1×10 4 mL g -1 , which is significantly higher than the distribution coefficient of other coexisting ions, showing high selectivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a diagram of the preparation process of Example 1 of the present invention.

[0024] Figure 2 This is an SEM image of the metal-organic framework adsorption material prepared in Example 1 of the present invention.

[0025] Figure 3 This is an isothermal adsorption curve of the metal organic framework adsorption material prepared in Example 1 of the present invention.

[0026] Figure 4 This is a diagram showing the effect of adsorption temperature on the adsorption capacity of the metal organic framework adsorption material prepared in Example 1.

[0027] Figure 5 This is a diagram showing the effect of different pH values ​​on the adsorption performance of the metal organic framework adsorption material prepared in Example 1.

[0028] Figure 6 This is a diagram showing the influence of the affinity of coexisting ions on the metal organic framework adsorption material prepared in Example 1.

[0029] Figure 7 In the figure, (a) is a schematic diagram of treating antimony-containing aqueous solution with a single metal-organic framework adsorption material fixed bed; (b) is an adsorption breakthrough curve of a single metal-organic framework adsorption material fixed bed; (c) is a decomposition curve of a single metal-organic framework adsorption material fixed bed.

[0030] Figure 8 In the figure, (a) is a schematic diagram of treating antimony-containing aqueous solution by connecting three metal-organic framework material fixed beds in series; (b) is an adsorption breakthrough curve diagram of three metal-organic framework material fixed beds in series; (c) is a decomposition curve diagram of three metal-organic framework adsorption material fixed beds in series. DETAILED DESCRIPTION

[0031] The following is a detailed description of the technical solutions in the embodiments of the present invention, using preferred embodiments and accompanying drawings in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0032] It should be noted that all professional terms used in the present invention are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention. Unless otherwise specified, the various raw materials, reagents, instruments and equipment used in the following embodiments of the present invention can be purchased from the market or prepared by existing methods.

[0033] Example 1

[0034] A method for preparing a metal organic framework adsorption material comprises the following steps:

[0035] (1) Weigh 50 mg of Bi(NO3)3·5H2O and dissolve it in a beaker containing 50 mL of a 1:1 volume ratio N,N-dimethylformamide and methanol solution. Ultrasonicate and magnetically stir for 10 minutes to form a dispersed solution.

[0036] (2) Then, 150 mg of trimesic acid was added thereto and mixed thoroughly. The mixture was then ultrasonically treated for 10 minutes to make the solution a colorless, transparent and uniform mixture.

[0037] (3) The colorless and transparent mixed solution was transferred to a 100 mL stainless steel reactor lined with polytetrafluoroethylene for solvothermal reaction at a constant temperature of 180°C for 24 h.

[0038] (4) After the reaction is completed, the reactor is cooled naturally at room temperature, and the obtained product is centrifuged and then washed three times with N,N-dimethylformamide, methanol and water respectively. Finally, it is placed in a vacuum drying oven at 120°C and dried for 24 hours. The obtained dry white powder is the metal organic framework adsorption material. The preparation process is as follows: Figure 1 shown.

[0039] Example 2

[0040] A method for preparing a metal organic framework adsorption material comprises the following steps:

[0041] (1) Weigh 50 mg of Bi(NO3)3·5H2O and dissolve it in a beaker containing 50 mL of a 2:1 volume ratio N,N-dimethylformamide and methanol solution. Ultrasonicate and magnetically stir for 10 minutes to form a dispersed solution.

[0042] (2) Then, 50 mg of trimesic acid was added thereto and mixed thoroughly. The mixture was then ultrasonically treated for 10 minutes to make the solution a colorless, transparent and uniform mixture.

[0043] (3) The colorless and transparent mixed solution was transferred to a 100 mL stainless steel reactor lined with polytetrafluoroethylene for solvothermal reaction at a constant temperature of 120°C for 72 h.

[0044] (4) After the reaction is completed, the reactor is naturally cooled at room temperature, and the obtained product is centrifuged and then washed three times with N,N-dimethylformamide, methanol and water respectively. Finally, it is placed in a vacuum drying oven at 120°C and dried for 24 hours. The obtained dry white powder is the metal organic framework adsorption material.

[0045] Example 3

[0046] A method for preparing a metal organic framework adsorption material comprises the following steps:

[0047] (1) Weigh 50 mg of Bi(NO3)3·5H2O and dissolve it in a beaker containing 50 mL of a 4:1 volume ratio N,N-dimethylformamide and methanol solution. Ultrasonicate and magnetically stir for 10 minutes to form a dispersed solution.

[0048] (2) Then, 250 mg of trimesic acid was added thereto and mixed thoroughly. The mixture was then ultrasonically treated for 10 minutes to make the solution a colorless, transparent and uniform mixture.

[0049] (3) The colorless and transparent mixed solution was transferred to a 100 mL stainless steel reactor lined with polytetrafluoroethylene for solvothermal reaction at a constant temperature of 200°C for 12 h.

[0050] (4) After the reaction is completed, the reactor is naturally cooled at room temperature, and the obtained product is centrifuged and then washed three times with N,N-dimethylformamide, methanol and water respectively. Finally, it is placed in a vacuum drying oven at 120°C and dried for 24 hours. The obtained dry white powder is the metal organic framework adsorption material.

[0051] Result Analysis

[0052] Figure 2 This is a SEM image of the metal organic framework adsorption material prepared in Example 1 of the present invention. The SEM image clearly shows that the metal organic framework adsorption material has a regular hexagonal rod structure with a very smooth surface. Its diameter is about 0.8 μm and its length is 4 μm. The hexagonal structure of the adsorption material of the present invention is mainly due to the high charge density of the cation Bi 3+ The high coordination number and flexible coordination mode form a strong coordination mode with the rigid ligand trimesic acid, and form a periodic and orderly arranged coordination network combination mode through self-assembly linking. 3+ , 9 carboxyl ligand units of trimesic acid and 9 coordinated water molecules constitute a repeating structural unit, each Bi 3+ The ions will bind to the two adjacent Bi 3+ By sharing the O atoms on the four carboxyl ligand units, these repeated structural units form a hexagonal prism structure with open pores.

[0053] Pentavalent antimony solution was prepared by dissolving potassium pyroantimonate in ultrapure water. 5.398 g KSbO6H6 was dissolved in 1 L of ultrapure water by ultrasonication to prepare 2.5 g L -1 Sb(OH) 6- Stock solution, and by diluting the stock solution to the Sb(OH) 6-Concentration, Sb(OH) in water samples was determined using a continuous light source atomic absorption spectrometer 6- concentration, used to evaluate the metal organic framework adsorbent for Sb(OH) 6- All experiments in the present invention were carried out three times, and the final data was the average value of the three experiments.

[0054] 20 mg of the metal organic framework adsorption material prepared in Example 1 was added to 20 mL of Sb(OH) 6- The solution was shaken in a constant temperature shaker at 318K for 12 h with the speed set at 180 rpm. The initial concentration of the adsorption solution was 50 mg L -1 , 100mg L -1 , 300mg L -1 , 500mg L -1 , 800mg L -1 , 1000mg L -1 , 1200mg L -1 , 1400mg L -1 , 1600mgL -1 After adsorption equilibrium, the sample was taken out and filtered through a 0.45 μm polyethersulfone membrane to obtain the supernatant. Sb(OH) 6- The concentration changes before and after adsorption were measured using a ContrAA 700 high-resolution continuous light source atomic absorption spectrometer. Figure 3 The isothermal adsorption curve of the metal organic framework adsorption material prepared in Example 1 of the present invention shows that the metal organic framework adsorption material has an adsorption capacity of Sb(OH) 6- Maximum adsorption capacity of ions Q max It is 850 mg / g, showing an ultra-high adsorption capacity.

[0055] 20 mg of metal organic framework adsorbent was added to 20 mL of Sb(OH) 6- The solution was shaken in a thermostat incubator at 288K, 303K and 318K for 12 h, with the rotation speed set at 180 rpm. The initial concentration of the adsorption solution was 50 mg L -1 ~2500mg L -1 After adsorption equilibrium, the sample was taken out and filtered through a 0.45 μm polyethersulfone membrane to obtain the supernatant. Sb(OH) 6- The concentration changes before and after adsorption were measured using a ContrAA 700 high-resolution continuous light source atomic absorption spectrometer. Figure 4 The effect of adsorption temperature on the adsorption capacity of the metal organic framework adsorption material prepared in Example 1 is shown in the figure. The results show that the metal organic framework adsorption material has a good adsorption capacity for Sb(OH)6 -The adsorption of ions increases with increasing temperature.

[0056] Prepare 5 50 mL volumes with an initial concentration of 200 mg L -1 Sb(OH)6 - solution, Sb(OH)6 - The pH range of the solution was adjusted to 1-11. - 50 mg of the metal organic framework adsorption material of the present invention was added to the solution. The solution was shaken in a constant temperature shaker at 303K for 2 hours. After adsorption equilibrium, the supernatant solution was collected by filtration through a pinhole filter membrane. The Sb(OH)6 - The concentration was measured using a ContrAA 700 high-resolution continuous light source atomic absorption spectrometer. Figure 5 As shown, the results show that the metal organic framework adsorption material has a strong acid and base effect on Sb(OH)6 - Ions are still well adsorbed, the adsorption material is resistant to strong acids and alkalis, and has a wide range of adsorption applications.

[0057] Selective adsorption: 50 mg of metal organic framework adsorbent was added to 50 mL of Sb(OH)6 - ,As(V),PO4 3- , SO4 2- , NO 3- , Cl - , Zn 2+ ,Co 2+ , Ni 2+ and Cd 2+ The ion concentration was 200 μg / L -1 The mixture was shaken in a 30°C constant temperature shaker for 12 hours. After adsorption equilibrium, the supernatant was collected by pinhole filtration. The concentration of each component ion in the supernatant was determined using a ContrAA 700 high-resolution continuous light source atomic absorption spectrometer and ion chromatography. The results are as follows: Figure 6 As shown in the figure, it can be seen that the metal organic framework adsorption material can absorb Sb(OH) 6- The selective separation of Sb(OH) and other metal ions indicates that the metal organic framework adsorption material of the present invention has a good effect on the adsorption of Sb(OH) in a complex antimony-containing mixed solution. 6- Has excellent selectivity.

[0058] Practical Application

[0059] (1) Short-term fixed bed of single metal-organic framework adsorbent

[0060] The operation time and working efficiency of the adsorption fixed bed have always been a very important issue in engineering applications.6- When treating wastewater, the adsorption fixed bed should be reasonably designed and arranged to promote the Sb(OH) 6- Capture of. Figure 7 Figure (a) shows a schematic diagram of a single MOF fixed bed treating an antimony-containing aqueous solution. A QP-01 vacuum pump provides flow system power. The PVC adsorption column has a diameter of 1.3 cm and a height of 6 cm. The MOF adsorption column is filled to a height of 1.1 cm and has a mass of 0.3 g. Total organic carbon in tap water = 0.41 mg L-1. -1 , pH = 7.24. Sb(OH) added to tap water 6- The initial concentration of the solution C0 is 200 μg L -1 , Sb(OH) 6- The solution was at 1.93 cm min -1 The adsorption was carried out under the loading flow rate of the adsorption column, and the empty bed contact time EBCT of a single column was 0.570min. 6- After completion, the -1 The adsorption column was analyzed using a flow rate of 0.1 M HCl eluent.

[0061] In fixed bed experiments, the effluent was collected in aliquots of 30 mL of sample effluent as the minimum required for analysis, which is approximately 20 bed volumes. Figure 7 As shown in (b), rapid adsorption breakthrough occurs in a single fixed bed with an initial concentration of 200 μg L -1 , the flow rate is 1.93cm / min, the empty bed contact time is 0.570min, when the concentration of the effluent reaches Sb(OH) 6- The maximum contaminant concentration allowed in drinking water is 6 μg L -1 , that is, when the absorption breakthrough point C / C0=0.03, a single metal organic framework adsorption material fixed bed can process Sb(OH) 6- The volume is about 1260BV, or 1838mL. At the point of complete adsorption saturation, i.e., exhaustion point C / C0 = 0.95, the volume that can be processed by a single fixed adsorption bed is about 2037BV, or 2972mL. 6- The adsorption breakthrough curve is formed gradually, Sb(OH) 6- Diffusion takes a long time to reach the adsorption site, which is controlled by the mass transfer within the particle. Assuming infinite mass transfer rate, when the adsorption breakthrough point is reached, the adsorption breakthrough curve will be perpendicular to the X-axis. Figure 7In (c), a single adsorption bed was eluted using 0.1M HCl, and the treatment volume to achieve complete desorption was 70BV, or 102mL. This means that 1838mL of antimony-containing wastewater can be treated by a single column while consuming 102mL of eluent. The above results verify that metal-organic framework adsorption materials can be used as adsorbents to treat actual Sb(OH) 6- Suitability of wastewater.

[0062] (2) Three short-term fixed beds filled with metal organic framework adsorption materials in series

[0063] Three single fixed adsorption beds were connected in series as a whole to evaluate the adsorption of Sb(OH) 6- Wastewater treatment effect. Figure 8 (a) is a schematic diagram of three metal-organic framework adsorption material fixed beds connected in series to treat antimony-containing aqueous solution. Figure 8 (b) shows the adsorption breakthrough curve of wastewater treated by three columns in series, with an initial concentration of 200 μg L -1 , the flow rate is 1.93 cm / min, the empty bed contact time is 0.570 min, when the concentration of the effluent reaches Sb(OH) 6- The maximum allowable emission pollution concentration is 6μg L -1 , that is, when the breakthrough point C / C0=0.03, the three-column bed in series can process Sb(OH) 6- The volume is approximately 1440 BV, or 6303 mL. At the point of complete adsorption saturation, or exhaustion point C / C0 = 0.95, the volume that the three-column bed in series can process is approximately 2210 BV, or 9673 mL. The processing volume of the three-column bed in series, 6303 mL, is 3.43 times the processing volume of the single-column adsorption bed, 1838 mL. The three-column bed in series can more thoroughly utilize the metal-organic framework adsorption material to remove Sb(OH) 6- As time goes by, the adsorption is concentrated in different areas of the adsorption bed. Due to sufficient contact, the mass transfer inside the particles is enhanced, thereby improving the utilization of adsorption sites. Sb(OH) adsorbed on Bi-MOF 6- It can be completely resolved with 0.1M HCl solution, and the processing volume is about 85BV, i.e. 372mL. The results are as follows Figure 8 As shown in (c), the total empty bed contact time of the three-column bed in series is 1.71 min. It can be deduced that the total bed volume of the three-column bed in series is 4.377 mL, and 842 BV, or 3686 mL of Sb(OH) can be processed per day. 6- Wastewater. The ability to treat such a large volume of wastewater is impressive for such small columns. The use of these series-connected adsorption beds provides a simple and effective process for the efficient removal of adsorbents from real industrial wastewater.

[0064] In summary, the present invention uses soluble bismuth salt as metal source and trimesic acid as connecting ligand to prepare a metal organic framework adsorption material with specific pocket capture channels through solvent thermal reaction. The porous organic framework adsorbent formed by the present invention has high charge density of cationic Bi 3+ The high coordination number and flexible coordination mode of the metal organic framework adsorption material have the characteristics of matching Sb(OH) 6- The pore structure is large and favorable for Sb(OH) 6- The metal organic framework adsorption material with open pocket capture channels is developed based on the inherent structural properties of the material itself to form Bi-O-Sb bonds at the active sites of the adsorption material for selective capture of Sb(OH) in water. 6- Targeted capture to achieve a dual improvement in adsorption capacity and selectivity.

[0065] It should be noted that when the present invention relates to numerical ranges, it should be understood that both endpoints of each numerical range and any value between the two endpoints can be selected. Since the steps and methods used are the same as those in the embodiments, in order to avoid redundancy, the present invention describes the preferred embodiments. Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they understand the basic inventive concepts. Therefore, the attached protection scope is intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0066] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the present invention and its equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A metal-organic framework adsorption material selectively captures Sb(OH)6 in antimony-containing wastewater - The application is characterized in that The preparation method of the metal organic framework adsorption material comprises the following steps: In an organic solvent, a metal-organic framework adsorbent with specific pocket-type capture channels was prepared by a solvothermal reaction using a soluble bismuth salt as the metal source and trimesic acid as the connecting ligand. The soluble bismuth salt was Bi(NO3)3·5H2O. The mass ratio of the soluble bismuth salt to trimesic acid was 1:

3. The solvothermal reaction temperature was 180°C and the reaction time was 24 h. The organic solvent was a mixed solvent of N,N-dimethylformamide and methanol. In the mixed solvent, the volume ratio of N,N-dimethylformamide to methanol was 1-4:

1. The concentration of antimony-containing wastewater was 50 mg / L-2000 mg / L, and the dosage ratio of the metal-organic framework adsorbent to antimony-containing wastewater was 1 mg:1 mL-4 mL.

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