A method for preparing a MOFs membrane for removing methyl orange in an aqueous solution
By preparing MOF membrane materials, the problem of secondary pollution in the removal of methyl orange from aqueous solution by powdered porous materials was solved, achieving efficient removal and stable presence, especially under different acid and alkaline conditions, and with good recyclability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- NINGDE NORMAL UNIV
- Filing Date
- 2026-06-24
- Publication Date
- 2026-07-24
Smart Images
Figure CN122441291A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of water purification technology, and specifically to a method for preparing a MOF membrane for removing methyl orange from aqueous solutions. Background Technology
[0002] Methyl orange is a common azo dye widely used in textiles, printing and dyeing, papermaking, and chemical industries. However, the large-scale discharge of this dye during its production and use has caused serious pollution to surface water and the ecological environment. Studies have shown that methyl orange has high chemical stability and is difficult to degrade naturally. Long-term exposure or ingestion through water may cause serious diseases such as cell mutation and cancer. Therefore, how to efficiently remove methyl orange from aqueous solutions is an important issue concerning human health and the sustainable development of the ecological environment.
[0003] Currently, the main methods for removing methyl orange from water are as follows: (1) photodegradation, which involves the decomposition and fading of methyl orange through ultraviolet-visible light irradiation, usually requiring the use of photocatalytic materials; (2) physical methods, which use coagulants or flocculants to aggregate and settle methyl orange molecules in aqueous solution; (3) biodegradation, which relies on specific microorganisms to release special biological enzymes to degrade and remove dye macromolecules; and (4) advanced oxidation and ozonolysis, which use chemical oxidation processes to generate strong oxidizing free radicals to oxidize and degrade methyl orange. In contrast, the porous material adsorption method is simpler to operate, has milder conditions, and is easier to implement. Therefore, in recent years, the use of porous materials to remove methyl orange from aqueous solution has attracted much attention. However, most current methods involve directly dispersing powder in water to achieve the adsorption and separation of this substance, which not only easily causes secondary pollution but also hinders the recycling of materials. Summary of the Invention
[0004] To address the aforementioned technical problems, the present invention aims to provide a method for preparing a MOF membrane for removing methyl orange from aqueous solutions. This MOF membrane has a stable structure, can efficiently remove methyl orange molecules from aqueous solutions, and also has good recyclability.
[0005] The technical solution of this invention to solve the above-mentioned technical problems is as follows: A method for preparing a MOF membrane for removing methyl orange from aqueous solution is provided, comprising the following steps:
[0006] (1) 1,3,5-pyromellitic acid and N,N-dimethylformamide were ultrasonically mixed, then zirconium oxychloride and formic acid were added and ultrasonically mixed. The mixture was heated and reacted under closed conditions. After centrifugation, the mixture was soaked in N,N-dimethylformamide and acetone in sequence, and then dried to obtain metal-organic framework material.
[0007] (2) Mix metal-organic framework material, polyethersulfone and N,N-dimethylacetamide, then coat it on a glass plate, dry it to form a film and separate it to obtain a MOF membrane for removing methyl orange from aqueous solution.
[0008] Furthermore, in step (1), the mass-to-volume ratio of 1,3,5-trimethylbenzene, N,N-dimethylformamide, zirconium oxychloride and formic acid is 80-120 mg: 20-30 mL: 350-450 mg: 10-15 mL.
[0009] Furthermore, in step (1), the reaction is heated at 120-140℃ for 2.5-3.5 days.
[0010] Furthermore, in step (1), the sample is first soaked in N,N-dimethylformamide for 2.5-3.5 days, and then soaked in acetone for 2.5-3.5 days.
[0011] Furthermore, before soaking, wash and centrifuge with the appropriate reagent (N,N-dimethylformamide or acetone).
[0012] Furthermore, during soaking, change the N,N-dimethylformamide or acetone three times a day.
[0013] Furthermore, in step (2), the mass-to-volume ratio of the metal-organic framework material, polyethersulfone, and N,N-dimethylacetamide is 0.45-0.75 g: 1.5 g: 9 mL.
[0014] The present invention also provides a MOFs membrane for removing methyl orange from aqueous solution prepared by the above-described method for preparing MOFs membrane for removing methyl orange from aqueous solution.
[0015] Furthermore, the thickness of the MOF film is 30-35 μm.
[0016] Furthermore, the specific surface area of MOF membranes is 1850-1950 m². 2 g -1 The pore volume is 0.60-0.70 cm³. 3 g -1 The aperture size is 16-20 Å.
[0017] The present invention also provides the application of the above-mentioned MOF membrane for removing methyl orange from aqueous solution.
[0018] The present invention has the following beneficial effects:
[0019] The MOF membrane material prepared in this invention exhibits a porous surface structure and a loose, porous, sponge-like cross-section, enabling it to efficiently remove over 98% of methyl orange molecules from aqueous solutions. Comparison with the adsorption effect of a pure polymer membrane (PES membrane) on methyl orange shows that the removal of methyl orange from aqueous solutions by this MOF membrane material is primarily achieved through the adsorption of MOFs. However, pure MOFs cannot form a self-supporting membrane material; cross-linking with a polymer (polyethersulfone) is required to form a stable membrane material. Attached Figure Description
[0020] Figure 1 The X-ray powder diffraction pattern of the metal-organic framework material in Example 1;
[0021] Figure 2 This is a scanning electron microscope image of the metal-organic framework material in Example 1;
[0022] Figure 3 The nitrogen adsorption diagram is shown for the metal-organic framework material in Example 1.
[0023] Figure 4 This is a pore size distribution diagram of the metal-organic framework material in Example 1;
[0024] Figure 5 The X-ray powder diffraction patterns of the metal-organic framework material in Example 1 after immersion in solutions of different pH values are shown.
[0025] Figure 6 This is a diagram showing the adsorption effect of the metal-organic framework material in Example 1 on methyl orange in aqueous solution;
[0026] Figure 7 Image of the MOF membrane sample prepared in Example 1;
[0027] Figure 8 X-ray powder diffraction patterns of the film materials in Examples 1, 2, and 1 (Comparative Example 1);
[0028] Figure 9 This is a scanning electron microscope image of the MOF film surface in Example 1 at 2000x magnification;
[0029] Figure 10 This is a scanning electron microscope image of the MOF film surface in Example 1 at 10,000x magnification;
[0030] Figure 11 This is a scanning electron microscope image of the MOF film surface in Example 1 at 50,000x magnification;
[0031] Figure 12 This is an elemental distribution diagram of the MOFs film surface in Example 1;
[0032] Figure 13 This is a scanning electron microscope image of the MOFs membrane cross-section in Example 1 at 10,000x magnification;
[0033] Figure 14 This is a scanning electron microscope image of the MOFs membrane cross-section in Example 1 at 20,000x magnification;
[0034] Figure 15 This is a scanning electron microscope image of the MOFs membrane cross-section in Example 1 at 50,000x magnification;
[0035] Figure 16 The elemental distribution diagram of the MOF membrane cross section in Example 1 is shown.
[0036] Figure 17 A schematic diagram of an experimental setup for removing methyl orange from aqueous solution using MOF membrane materials;
[0037] Figure 18 The graph shows a comparison of the adsorption effects of the membrane materials in Example 1, Example 2, and Comparative Example 1 on methyl orange in aqueous solution.
[0038] Figure 19 The graph shows the adsorption effect of the MOF membrane in Example 1 on methyl orange in different volumes of aqueous solution.
[0039] Figure 20 The graph shows the test results of the recycling performance of the MOF membrane in Example 1.
[0040] Figure 21 The graph shows the adsorption effect test results of the MOF membrane in Example 1 on methyl orange in aqueous solutions containing different concentrations of sodium chloride. Detailed Implementation
[0041] The principles and features of this invention are described below. The examples given are for illustrative purposes only and are not intended to limit the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer should be followed. Reagents or instruments whose manufacturers are not specified are all commercially available products.
[0042] Example 1
[0043] A MOF membrane (MOF-PES-2) for removing methyl orange from aqueous solution is prepared by the following steps:
[0044] (1) 1,3,5-Pyromellitic acid and N,N-dimethylformamide were ultrasonically mixed, and then zirconium oxychloride and formic acid were added and ultrasonically mixed. The mixture was heated at 120°C for 3.5 days under sealed conditions. After centrifugation, N,N-dimethylformamide was used for 3.5 days, and then acetone was used for 3.5 days. The mixture was changed 3 times a day. After drying, metal-organic framework material was obtained. The mass-volume ratio of 1,3,5-pyromellitic acid, N,N-dimethylformamide, zirconium oxychloride and formic acid was 105 mg: 22.5 mL: 385 mg: 12.5 mL.
[0045] (2) Mix metal-organic framework material, polyethersulfone and N,N-dimethylacetamide, then coat it on a glass plate, dry it to form a film and separate it to obtain a MOF membrane for removing methyl orange from aqueous solution; the mass-volume ratio of metal-organic framework material, polyethersulfone and N,N-dimethylacetamide is 0.75 g: 1.5 g: 9 mL.
[0046] Example 2
[0047] A MOF membrane (MOF-PES-1) for removing methyl orange from aqueous solution is prepared by the following steps:
[0048] (1) 1,3,5-Pyromellitic acid and N,N-dimethylformamide were ultrasonically mixed, and then zirconium oxychloride and formic acid were added and ultrasonically mixed. The mixture was heated at 140°C for 2.5 days under sealed conditions. After centrifugation, N,N-dimethylformamide was used for 2.5 days, and then acetone was used for 2.5 days. The mixture was changed 3 times a day. After drying, metal-organic framework material was obtained. The mass-volume ratio of 1,3,5-pyromellitic acid, N,N-dimethylformamide, zirconium oxychloride and formic acid was 80 mg: 20 mL: 350 mg: 10 mL.
[0049] (2) Mix metal-organic framework material, polyethersulfone and N,N-dimethylacetamide, then coat it on a glass plate, dry it to form a film and separate it to obtain a MOF membrane for removing methyl orange from aqueous solution; the mass-volume ratio of metal-organic framework material, polyethersulfone and N,N-dimethylacetamide is 0.45 g: 1.5 g: 9 mL.
[0050] Example 3
[0051] A MOF membrane (MOF-PES-3) for removing methyl orange from aqueous solution is prepared by the following steps:
[0052] (1) 1,3,5-Pyromellitic acid and N,N-dimethylformamide were ultrasonically mixed, and then zirconium oxychloride and formic acid were added and ultrasonically mixed. The mixture was heated at 130°C for 3 days under sealed conditions. After centrifugation, N,N-dimethylformamide was used for 3 days, and then acetone was used for 3 days. The mixture was changed 3 times a day. After drying, metal-organic framework material was obtained. The mass-volume ratio of 1,3,5-pyromellitic acid, N,N-dimethylformamide, zirconium oxychloride and formic acid was 120 mg: 30 mL: 450 mg: 15 mL.
[0053] (2) Mix metal-organic framework material, polyethersulfone and N,N-dimethylacetamide, then coat it on a glass plate, dry it to form a film and separate it to obtain a MOF membrane for removing methyl orange from aqueous solution; the mass-volume ratio of metal-organic framework material, polyethersulfone and N,N-dimethylacetamide is 0.6 g: 1.5 g: 9 mL.
[0054] Comparative Example 1
[0055] A polyethersulfone (PES) film, the preparation method of which includes the following steps:
[0056] (2) Mix polyethersulfone and N,N-dimethylacetamide at a mass-volume ratio of 1.5 g: 9 mL, then coat the mixture onto a glass plate, dry it to form a film, and then separate the film to obtain a polyethersulfone membrane.
[0057] Experimental Example 1
[0058] (1) The X-ray powder diffraction pattern and scanning electron microscope image of the metal-organic framework material prepared in Example 1 are shown below. Figure 1 and Figure 2 As shown.
[0059] Depend on Figure 1 It can be seen that the PXRD diffraction peak positions of the experimental sample highly match the theoretically simulated PXRD diffraction peak positions of MOF-808, indicating that the prepared MOF-808 has high purity and crystallinity. Figure 2 It can be seen that the MOF-808 sample particles exhibit a uniform and regular octahedral morphology, which also indicates that the prepared MOF-808 has high purity.
[0060] (2) The pore structure of the metal-organic framework material prepared in Example 1 was tested. The test results of nitrogen adsorption performance and pore size distribution are as follows: Figure 3 and Figure 4 As shown.
[0061] As shown in the figure, the nitrogen adsorption capacity of this material is approximately 569 cm⁻¹. 3 g -1 The BET and pore volumes are 1910 m³. 2g -1 0.654 cm 3 g -1 The pore size is approximately 18 Å. The results show that the metal-organic framework material prepared by this method has a high specific surface area and a porous structure, which is beneficial to the diffusion and adsorption of methyl orange, thereby removing methyl orange molecules from water.
[0062] (3) The stability of the metal-organic framework material prepared in Example 1 in aqueous solutions with different pH values was tested.
[0063] 30 mg of dried metal-organic framework material solid powder was weighed into twelve 5 mL centrifuge tubes, and 2 mL of solutions with pH values of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, and 12 were added to each tube. The tubes were soaked for 36 h. After centrifugation and washing three times with ultrapure water, the tubes were washed three times with acetone and then dried in a vacuum drying oven. After drying, X-ray powder diffraction was used to monitor whether the structure changed. The results are as follows: Figure 5 As shown.
[0064] As can be seen from the figure, the powder X-ray diffraction pattern of the MOFs did not change significantly within the pH range of 1-12, indicating that the MOFs can exist stably in acidic, neutral and alkaline aqueous solutions. This suggests that its framework structure has high water temperature stability, making it suitable for removing pollutants from water under various acid and alkaline conditions.
[0065] (4) The adsorption effect of the metal-organic framework material prepared in Example 1 on methyl orange in aqueous solution was tested.
[0066] Weigh 20 mg of dry metal-organic framework material solid powder and add it to 100 mL of 30 mg·L⁻¹ -1 In a methyl orange solution, the adsorption capacity (Qt) of methyl orange was tested at different times, and the results are as follows: Figure 6 As shown.
[0067] The Qt calculation formula is as follows:
[0068] Qt = (C0 - Ct)
[0069] Where: Qt (mg·g) -1 v(100 mL) represents the adsorption capacity of MOF-808 for methyl orange at time t; v(100 mL) represents the volume of the methyl orange aqueous solution; and m(20 mg) represents the mass of MOF-808.
[0070] As shown in the figure, MOF-808 exhibits a significant adsorption effect on methyl orange within the first 10 minutes, and the calculated adsorption capacity reaches 64.99 mg·g⁻¹.-1 Within 10–40 min, the adsorption capacity of MOF-808 for methyl orange gradually increased to 107.23 mg·g⁻¹. -1 Within 40–120 min, the adsorption capacity of methyl orange increased slowly, gradually approaching adsorption equilibrium and finally reaching an adsorption capacity of 132.19 mg·g. -1 It is evident that MOF-808 can rapidly adsorb methyl orange from aqueous solution, and 20 mg of MOF-808 solid powder achieved a removal efficiency of up to 88.13% for methyl orange (100 mL volume, 30 mg / L concentration) in aqueous solution within 120 min. The results indicate that the metal-organic framework material prepared in this invention has a good adsorption effect on methyl orange in aqueous solution.
[0071] Experimental Example 2
[0072] (1) The MOF membrane prepared in Example 1 is as follows Figure 7 As shown. The X-ray powder diffraction patterns of the MOF films prepared in Examples 1 and 2, and the polyethersulfone film prepared in Comparative Example 1 are shown below. Figure 8 As shown.
[0073] The results showed that obvious diffraction peaks (5°~15°) of MOF-808 appeared in the PXRD spectra of MOF films, indicating that the structure of MOF-808 in MOF films did not change significantly and retained the original framework structure.
[0074] (2) Scanning electron microscope images of the MOFs film surface prepared in Example 1 at different magnifications are shown below. Figure 9-11 As shown, the element distribution is as follows Figure 12 As shown; scanning electron microscope images of the cross-section of the MOF film at different magnifications are shown below. Figure 13-15 As shown, the element distribution is as follows Figure 16 As shown.
[0075] As shown in the figure, the surface of the MOF membrane exhibits a porous structure, while the cross-section displays a loose, porous, sponge-like structure. Furthermore, X-ray powder diffraction results clearly show that a large amount of metal-organic framework material (MOF-808) is distributed on both the surface and sides, thus fully leveraging the adsorption capacity of MOFs for methyl orange.
[0076] (3) Using the membrane materials prepared in Examples 1 and 2 and Comparative Example 1 as filter membranes, the removal efficiency of the prepared membrane materials for methyl orange in aqueous solution was tested using a sand core filtration device (only one vacuum filtration was performed in each experiment). The schematic diagram of the experimental device is shown below. Figure 17 As shown. The initial concentration of the methyl orange solution tested was 30 mg·L⁻¹. -1The volume was 10 mL. Removal efficiency R (%) represents the percentage of residual methyl orange concentration after filtration relative to the initial concentration (R = (1 - Ct / C0) * 100), and the results are as follows: Figure 18 As shown.
[0077] As shown in the figure, the removal efficiency of pure PES polymer membrane material is only 19.12%, while the removal efficiency is significantly improved after adding MOFs, increasing to 92.55% (MOF-PES-1) and 98.85% (MOF-PES-2), respectively. This indicates that MOFs in the membrane material are the main components for the removal and adsorption of methyl orange, with Example 1 showing the best performance.
[0078] (4) Using the membrane material prepared in Example 1 as the filter membrane, methyl orange (initial concentration of 30 mg·L⁻¹) was removed from the aqueous solution using a sand core filtration device. -1 ), filtering 10 mL, 25 mL, and 50 mL of solution each time, and the test results are as follows. Figure 19 As shown, the removal efficiency was 98.85, 98.91, and 58.82, respectively, indicating that the membrane material prepared in Example 1 has a certain removal capacity for different volumes of methyl orange solution, and the initial filtration efficiency of the membrane material for 10 mL and 25 mL methyl orange solution can reach more than 98%.
[0079] Then, after washing and soaking with industrial ethanol, it was recycled, and its recycling performance was tested. The results are as follows: Figure 20 As shown.
[0080] As shown in the figure, the membrane material prepared in Example 1 achieved a filtration efficiency of over 95% in the second cycle test for different volumes of methyl orange solution, and over 75% in the third cycle test. The results indicate that the membrane material has good recyclability.
[0081] (5) Considering that a large amount of inorganic salts, such as sodium chloride, are present in actual methyl orange wastewater, the membrane material prepared in Example 1 was used as the filter membrane, and a sand core filtration device was used to remove methyl orange (methyl orange concentration of 30 mg·L⁻¹) from the aqueous solution containing sodium chloride. -1 (volume is 10 mL), the test results are as follows Figure 21 As shown.
[0082] As shown in the figure, at the same concentration (30 mg·L⁻¹), -1 In a sodium chloride aqueous solution, the membrane material prepared in Example 1 still maintained a methyl orange removal efficiency of over 95%. Furthermore, when the sodium chloride concentration increased tenfold, the membrane material prepared in Example 1 was still able to remove 89.07% of the methyl orange from the aqueous solution. The results indicate that this membrane material also has a good removal effect on methyl orange solutions containing sodium chloride.
[0083] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for preparing a MOF membrane for removing methyl orange from aqueous solution, characterized in that, Includes the following steps: (1) 1,3,5-pyromellitic acid and N,N-dimethylformamide were ultrasonically mixed, then zirconium oxychloride and formic acid were added and ultrasonically mixed. The mixture was heated and reacted under closed conditions. After centrifugation, the mixture was soaked in N,N-dimethylformamide and acetone in sequence, and then dried to obtain metal-organic framework material. (2) The metal-organic framework material, polyethersulfone and N,N-dimethylacetamide are mixed, coated on a glass plate, dried to form a film and then separated to obtain a MOF membrane for removing methyl orange from an aqueous solution.
2. The method for preparing a MOF membrane for removing methyl orange from aqueous solution as described in claim 1, characterized in that, In step (1), the mass-to-volume ratio of 1,3,5-trimethylbenzene, N,N-dimethylformamide, zirconium oxychloride and formic acid is 80-120 mg: 20-30 mL: 350-450 mg: 10-15 mL.
3. The method for preparing a MOF membrane for removing methyl orange from aqueous solution as described in claim 1, characterized in that, In step (1), the reaction is carried out at 120-140℃ for 2.5-3.5 days.
4. The method for preparing a MOF membrane for removing methyl orange from aqueous solution as described in claim 1, characterized in that, In step (1), first soak in N,N-dimethylformamide for 2.5-3.5 days, then soak in acetone for 2.5-3.5 days.
5. The method for preparing a MOF membrane for removing methyl orange from aqueous solution as described in claim 4, characterized in that, During soaking, change the N,N-dimethylformamide or acetone 3 times a day.
6. The method for preparing a MOF membrane for removing methyl orange from aqueous solution as described in claim 1, characterized in that, In step (2), the mass-to-volume ratio of the metal-organic framework material, polyethersulfone, and N,N-dimethylacetamide is 0.45-0.75 g: 1.5 g: 9 mL.
7. The MOFs membrane for removing methyl orange from aqueous solution prepared by the method of any one of claims 1-6.
8. The MOF membrane for removing methyl orange from aqueous solution as described in claim 7, characterized in that, The thickness of the MOFs film is 30-35 μm.
9. The MOF membrane for removing methyl orange from aqueous solution as described in claim 7, characterized in that, The specific surface area of the MOF membrane is 1850-1950 m². 2 g -1 The pore volume is 0.60-0.70 cm³. 3 g -1 The aperture size is 16-20 Å.
10. The application of the MOF membrane for removing methyl orange from aqueous solution according to any one of claims 7-9.