Preparation of Cu and Ni doped modified MIL-88A material and application thereof in degradation of PFBS by activated potassium peroxymonosulfate

Abstract

This invention relates to the field of chemical method technology, specifically to the preparation of Cu and Ni-doped modified MIL-88A material and its application in the degradation of PFBS by activated potassium persulfate. The preparation involves ultrasonically dispersing and dissolving fumaric acid with CuCl2·2H2O, FeCl3·6H2O, and Ni(NO3·)2·6H2O, then mixing the mixture and reacting it at a specific temperature and rotation speed. The product is obtained after washing and drying. The application involves preparing PMS and PFBS solutions, adding the modified material, and reacting under specific conditions. This invention overcomes the limitations of existing MIL-88A catalytic active sites and the Fe... 3+ / Fe 2+ The problem of slow valence state cycle transitions.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of chemical methods, and in particular to preparation of a Cu and Ni doped modified MIL-88A material and application of the Cu and Ni doped modified MIL-88A material in degradation of PFBS by activated potassium monopersulfate. BACKGROUND

[0002] As a typical perfluoro and polyfluoro alkyl substance (PFASs), perfluorobutane sulfonic acid (PFBS) has excellent chemical stability, thermal stability and surface activity and is widely used in the fields of textiles, papermaking, electronics and the like; however, PFBS is difficult to be naturally degraded in the environment, is easy to be enriched in water bodies and soil, and enters organisms through the food chain, thereby posing a potential threat to the ecological environment and human health. At present, the methods for degrading PFBS mainly include advanced oxidation technology, adsorption method, biological degradation method and the like; among them, the advanced oxidation technology becomes one of the main means for treating PFBS because of the ability to generate strong oxidizing free radicals (such as ·OH, SO4 - ·, etc.).

[0003] In the advanced oxidation technology, potassium monopersulfate (PMS) as a common oxidant can efficiently generate sulfate radicals (SO4 - ·) under the action of an activator. On the one hand, if a traditional activator such as a transition metal ion (Fe 2+ , Co 2+ , etc. is used, there are problems such as easy loss, possible secondary pollution, narrow pH application range and the like; on the other hand, if a single metal organic framework (MOFs) material is used, the efficiency of activating PMS is low, which is difficult to meet the actual treatment demand.

[0004] Among them, MIL-88A as a typical MOFs material has the problems that it has adjustable pore structure and good stability, but the catalytic active site of single MIL-88A is limited, and the slow cyclic transformation of Fe 3+ / Fe 2+ valence states leads to the difficulty in meeting the actual water pollution treatment demand of the efficiency of activating PMS to degrade PFBS. SUMMARY

[0005] Therefore, the purpose of the present application is to provide a preparation of a Cu and Ni doped modified MIL-88A material and application of the Cu and Ni doped modified MIL-88A material in degradation of PFBS by activated potassium monopersulfate, so as to solve the problems of limited catalytic active site of the existing MIL-88A and slow cyclic transformation of Fe 3+ / Fe 2+ valence states.

[0006] In a first aspect, the present application discloses a preparation of a Cu and Ni doped modified MIL-88A material, comprising the following steps:

[0007] S1, 4.4800 g of fumaric acid was dissolved at 70°C to obtain A liquid in 640 mL of ultrapure water.

[0008] S2, 7.1456 g of CuCl2·2H2O and 11.2528 g of FeCl3·6H2O, 13.1250 g of Ni(NO3)2·6H2O were mixed and dissolved in 160 mL of ultrapure water at room temperature to obtain B liquid.

[0009] S3, the A liquid in step 1 and the B liquid in step 2 were mixed uniformly, and stirred at 110°C, 1200 r·min -1 for 5-6 h.

[0010] S4, after the reaction was completed and cooled, the precipitate was washed by centrifugation with ultrapure water and anhydrous ethanol, and dried at 80°C overnight.

[0011] Specifically, in S1, the fumaric acid was dissolved in 640 mL of ultrapure water, and ultrasonic dispersion was performed for 1 h using an ultrasonic cleaning instrument.

[0012] Specifically, in S2, CuCl2·2H2O, FeCl3·6H2O, and Ni(NO3)2·6H2O were dissolved in 160 mL of ultrapure water, and ultrasonic dispersion was performed for 1 h using an ultrasonic cleaning instrument.

[0013] Specifically, in S1, the molar ratio of Cu:Fe was 1:1.

[0014] In a second aspect, the application discloses an application of a Cu and Ni doped modified MIL-88A material in degrading PFBS by activated persulfate, and the application is applied to preparation of the Cu and Ni doped modified MIL-88A material, and comprises the following steps:

[0015] S1, a PMS solution of 1-10 mmol / L is prepared for standby.

[0016] S2, a PFBS solution of 2-8 mg / L is prepared for standby.

[0017] S3, a 100 mL polypropylene centrifuge tube is used as a reaction container, 20 mL of 5 mmol / L PMS and 20 mL of 2 mg / L PFBS are added into the reaction container, and 0.01-0.1 g of CNF-1 is added into the reaction container.

[0018] S4, the reaction container is placed in a constant-temperature shaker at 180 rpm, and the reaction is carried out at 25-45°C and pH=3-11, and a fixed-point sample is analyzed.

[0019] Specifically, in S1, a PMS solution of 5 mmol / L is prepared.

[0020] Specifically, a 2mg / L PFBS solution is prepared in S2.

[0021] Specifically, 0.05g of CNF-1 is added in S3.

[0022] Specifically, the reaction is carried out at 45℃ and pH=3 in S4.

[0023] The beneficial effects of the present application are:

[0024] First, by constructing a stable heterogeneous catalytic structure through double metal doping, the Cu, Ni and Fe active sites are firmly anchored in the MOFs material framework, significantly inhibiting the leaching behavior of metal ions, and fundamentally solving the problems of loss and secondary pollution of traditional homogeneous catalysts. Second, by utilizing the multi-metal synergistic effect between Cu / Ni and Fe, an efficient interface electron transfer channel is constructed, which greatly accelerates the regeneration and circulation rate of Fe 2+ , effectively overcoming the problem of low PMS activation efficiency caused by slow Fe 3+ / Fe 2 + conversion. Third, the electronic structure regulation of double metal doping further widens the pH application range of the catalytic system (which can adapt to neutral to weak alkaline actual water body environment), and improves the adaptability of the technology to practical application scenarios. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 FIG. 1 is a scanning electron microscope (SEM) image of the prepared metal organic framework material MIL-88A and derivatives.

[0026] Figure 2 FIG. 2 is a scanning electron microscope (SEM) image of the prepared metal organic framework material CM-1 and derivatives.

[0027] Figure 3 FIG. 3 is a scanning electron microscope (SEM) image of the prepared metal organic framework material CNF-1 and derivatives.

[0028] Figure 4 FIG. 4 is an X-ray photoelectron spectroscopy (XPS) image of the prepared metal organic framework material MIL-88A and derivatives.

[0029] Figure 5 FIG. 5 is an X-ray diffraction (XRD) image of the prepared metal organic framework material MIL-88A and derivatives.

[0030] Figure 6 FIG. 6 is a Zeta potential image of the prepared metal organic framework material MIL-88A and derivatives. DETAILED DESCRIPTION

[0031] To facilitate understanding of the present invention, a more comprehensive description of the invention will be provided below in conjunction with specific embodiments. Preferred embodiments of the invention are given in the specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0033] Example 1: This example provides a method for preparing Cu and Ni doped modified MIL-88A material (i.e., CNF-1 preparation). The specific steps are as follows:

[0034] Step 1: Dissolve 4.4800g of fumaric acid at 70℃ and obtain solution A in 640mL of ultrapure water.

[0035] Step 2: Take 7.1456g of CuCl2·2H2O, 11.2528g of FeCl3·6H2O (Cu:Fe molar ratio of 1:1), and 13.1250g of Ni(NO3)2·6H2O, and mix and dissolve them in 160mL of ultrapure water at room temperature to obtain solution B.

[0036] Step 3: Mix solution A from step 1 and solution B from step 2 thoroughly, and heat at 110℃ and 1200 rpm. -1 Stir for 5 hours under the specified conditions.

[0037] Step 4: After the reaction is complete and the mixture has cooled, wash the precipitate with ultrapure water and anhydrous ethanol by centrifugation, and dry it overnight at 80°C.

[0038] In step 1, when fumaric acid is dissolved in 640 mL of ultrapure water, it is ultrasonically dispersed for 1 hour using an ultrasonic cleaner.

[0039] In step 2, CuCl2·2H2O, FeCl3·6H2O, and Ni(NO3)2·6H2O were dissolved in 160 mL of ultrapure water and ultrasonically dispersed for 1 hour using an ultrasonic cleaner. After drying, the resulting solid was ground and then sieved through a 60-mesh standard sieve. The undersized product was collected, and finally, Cu and Ni doped modified MIL-88A material with uniform particle size was obtained.

[0040] Comparative Example 1: This embodiment provides a method for preparing MIL-88A material, with the following specific steps:

[0041] Step 1: Dissolve 4.4800g of fumaric acid at 70℃ and obtain solution A in 640mL of ultrapure water.

[0042] Step 2: Take 11.2528g of FeCl3·6H2O and dissolve it in 160mL of ultrapure water at room temperature to obtain solution B.

[0043] Step 3: Mix solution A from step 1 and solution B from step 2 thoroughly, and heat at 110℃ and 1200 rpm. -1 Stir for 5 hours under the specified conditions.

[0044] Step 4: After the reaction is complete and the mixture cools, wash the precipitate with ultrapure water and anhydrous ethanol by centrifugation, and dry it overnight at 80°C. After drying, grind the resulting solid and then sieve it through a 60-mesh standard sieve. Collect the undersized product to obtain MIL-88A material with uniform particle size.

[0045] In step 1, when fumaric acid is dissolved in 640 mL of ultrapure water, it is ultrasonically dispersed for 1 hour using an ultrasonic cleaner.

[0046] In step 2, when CuCl2·2H2O, FeCl3·6H2O, and Ni(NO3)2·6H2O are dissolved in 160mL of ultrapure water, they are ultrasonically dispersed for 1h using an ultrasonic cleaner.

[0047] Comparative Example 2, this embodiment provides a method for preparing Cu-doped modified MIL-88A material (i.e., the preparation of CM-1), and the specific steps are as follows:

[0048] Step 1: Dissolve 4.4800g of fumaric acid at 70℃ and obtain solution A in 640mL of ultrapure water.

[0049] Step 2: Take 7.1456g of CuCl2·2H2O and 11.2528g of FeCl3·6H2O (Cu:Fe molar ratio of 1:1), mix and dissolve them in 160mL of ultrapure water at room temperature to obtain solution B.

[0050] Step 3: Mix solution A from step 1 and solution B from step 2 thoroughly, and heat at 110℃ and 1200 rpm. -1 Stir for 5 hours under the specified conditions.

[0051] Step 4: After the reaction is complete and the mixture cools, wash the precipitate with ultrapure water and anhydrous ethanol by centrifugation, and dry it overnight at 80°C. After drying, grind the resulting solid and then sieve it through a 60-mesh standard sieve. Collect the undersized product to obtain Cu-doped modified MIL-88A material with uniform particle size.

[0052] In step 1, when fumaric acid is dissolved in 640 mL of ultrapure water, it is ultrasonically dispersed for 1 hour using an ultrasonic cleaner.

[0053] In step 2, when CuCl2·2H2O, FeCl3·6H2O, and Ni(NO3)2·6H2O are dissolved in 160mL of ultrapure water, they are ultrasonically dispersed for 1h using an ultrasonic cleaner.

[0054] Combining Example 1, Comparative Example 1, and Comparative Example 2, the analysis is as follows:

[0055] In Comparative Example 2, MIL-88A was in the form of a single Fe 3+ As the metal center, it serves as the core control sample; in Comparative Example 1, CM-1 was modified by introducing Cu. 2+ A Fe / Cu binary metal system was formed; in Example 1, Ni was further added to CNF-1. 2+ Construct a Fe / Cu / Ni ternary system; overall, CNF-1 metal synergy effect is more prominent, process efficiency is higher, and composition design is more precise; the above washing standard is to wash until ultrapure water and anhydrous ethanol are clear (for example, three times each of ultrapure water and anhydrous ethanol).

[0056] Compared with the prior art, the present invention has the following advantages and technical effects:

[0057] This invention proposes a Cu / Ni bimetallic doping modification solution for MIL-88A, overcoming three key technical challenges in the PFBS degradation process: First, by constructing a stable heterogeneous catalytic structure through bimetallic doping, the active sites of Cu, Ni, and Fe are firmly anchored within the MOF material framework, significantly inhibiting the leaching behavior of metal ions and fundamentally solving the problems of leaching and secondary pollution associated with traditional homogeneous catalysts; Second, by utilizing the synergistic effect of multiple metals between Cu / Ni and Fe, a highly efficient interfacial electron transfer channel is constructed, greatly accelerating the degradation of Fe. 2+ The regeneration cycle rate effectively overcomes the problem of Fe in single iron-based MIL-88A. 3+ / Fe 2+ The slow conversion process leads to low PMS activation efficiency; at the same time, the electronic structure regulation of bimetallic doping further broadens the pH range of the catalytic system (it can be adapted to neutral to weakly alkaline actual water environments), improving the adaptability of the technology to practical application scenarios.

[0058] Example 2: This example provides an application of Cu and Ni doped modified MIL-88A material in the degradation of PFBS by activated potassium peroxymonosulfate. The specific steps are as follows:

[0059] Experiment 1 compares the effects of different systems on the degradation of PFBS by catalytically activated PMS.

[0060] Step 1: Prepare a 5 mmol / L PMS (i.e., KHSO5) solution for later use.

[0061] Step 2: Prepare a 2 mg / L PFBS (perfluorobutane sulfonic acid) solution for later use.

[0062] Step 3: Using 100mL polypropylene centrifuge tubes as reaction vessels, add 20mL each of 5mmol / L PMS and 2mg / L PFBS to multiple reaction vessels; add different materials sequentially to the above multiple reaction vessels, with each reaction vessel having a specific addition amount of 0.05g: MIL-88A(Fe), CM-1, and CNF-1 correspond to different reactors, and complete the addition one by one.

[0063] Step 4: Place the above reaction vessels in a constant temperature shaker at 180 rpm and carry out the reaction at room temperature (25°C) and pH (5), and take samples at fixed points for analysis.

[0064] The removal rates of PFBS under different systems are shown in Table 1.

[0065] Time (min) Removal % (MIL-88A Fe) Removal % (CM-1) Removal % (CNF-1) Removal % (PMS) Removal % (MIL-88A Fe / PMS) Removal % (CM-1 / PMS) Removal % (CNF-1 / PMS) 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 5 0.00 1.60 5.2 0.00 16.95 26.61 56.74 15 0.50 0.90 7.2 0.00 30.53 43.51 76.55 30 0.30 2.50 6.9 0.60 29.96 45.32 78.55 45 1.00 2.90 7.5 0.30 31.07 47.64 79.49 60 1.30 3.40 8.2 0.80 32.29 49.41 79.90

[0066] Based on the above experimental steps and Table 1, it can be seen that the synthesized MOFs materials and PMS are difficult to effectively degrade PFBS when used alone. When the three catalysts MIL-88A, CM-1, and CNF-1 are used in combination with PMS, it can be found that after modification with copper and nickel, the removal rate of PFBS by MOFs materials activating PMS is significantly improved. Therefore, the CNF-1 / PMS system has the best degradation effect on PFBS.

[0067] Experiment 2 compares the effects of different CNF-1 dosages on the catalytic activation of PMS in the degradation of PFBS.

[0068] Step 1: Prepare a 5 mmol / L PMS solution for later use.

[0069] Step 2: Prepare a 2 mg / L PFBS solution for later use.

[0070] Step 3: Using 100mL polypropylene centrifuge tubes as reaction vessels, add 20mL each of 5mmol / L PMS and 2mg / L PFBS to multiple reaction vessels; add different materials sequentially to the above multiple reaction vessels, corresponding to 0.01gCNF-1, 0.02gCNF-1, 0.05gCNF-1, 0.08gCNF-1, and 0.10gCNF-1 for each reaction vessel respectively.

[0071] Step 4: Place the above reaction vessels in a constant temperature shaker at 180 rpm and carry out the reaction at room temperature (25°C) and pH (5), and take samples at fixed points for analysis.

[0072] The removal rates of PFBS under different CNF-1 dosages are shown in Table 2.

[0073] Time (min) Removal % (0.01) Removal % (0.02) Removal % (0.05) Removal % (0.08) Removal % (0.10) 0 0.00 0.00 0.00 0.00 0.00 5 21.71 29.53 56.74 55.77 46.76 15 40.16 49.63 76.55 72.24 65.32 30 41.95 50.38 78.55 73.47 66.22 45 42.01 51.39 79.49 73.95 66.96 60 42.97 51.51 79.90 73.98 67.14

[0074] Based on the above experimental steps and Table 2, we can conclude that:

[0075] As the CNF-1 dosage increased, the degradation rate of PFBS showed a trend of first increasing and then decreasing. When the dosage reached 0.05g, the degradation rate of PFBS reached its maximum of 79.90%. Considering both reaction efficiency and cost, a CNF-1 dosage of 0.05g is the optimal choice.

[0076] Experiment 3 compares the effects of different PMS concentrations on the degradation of PFBS by catalytically activated PMS.

[0077] Step 1: Prepare PMS solutions with concentrations of 1 mmol / L, 3 mmol / L, 5 mmol / L, 7 mmol / L, and 10 mmol / L for later use.

[0078] Step 2: Prepare a 2 mg / L PFBS solution for later use.

[0079] Step 3: Using 100mL polypropylene centrifuge tubes as reaction vessels, add 20mL of 2mg / L PFBS to each of the multiple reaction vessels; add 20mL of PMS (i.e., KHSO5) of different concentrations to the above multiple reaction vessels, corresponding to 1mmol / L, 3mmol / L, 5mmol / L, 7mmol / L, and 10mmol / L respectively; add 0.05g CNF-1 to each of the above multiple reaction vessels.

[0080] Step 4: Place the above reaction vessels in a constant temperature shaker at 180 rpm and carry out the reaction at room temperature (25°C) and pH (5), and take samples at fixed points for analysis.

[0081] The removal rates of PFBS at different PMS concentrations are shown in Table 3.

[0082] Time (min) Removal % (1.00) Removal % (3.00) Removal % (5.00) Removal % (7.00) Removal % (10.0) 0 0.00 0.00 0.00 0.00 0.00 5 45.49 50.48 56.74 53.14 45.35 15 56.60 65.91 76.55 71.95 62.43 30 56.89 66.02 78.55 72.41 62.87 45 57.59 66.36 79.49 73.39 63.09 60 57.97 66.46 79.90 73.45 63.29

[0083] Based on the above experimental steps and Table 3, we can conclude that:

[0084] With increasing PMS concentration, the removal rate of PFBS showed a trend of first increasing and then decreasing. When the PMS concentration was 5 mmol / L, the degradation rate of PFBS reached its maximum of 79.90%. Considering both reaction efficiency and cost, a KHSO5 concentration of 5 mmol / L was the optimal choice.

[0085] Experiment 4 compares the effects of different PFBS concentrations on the catalytic activation of PMS in the degradation of PFBS.

[0086] Step 1: Prepare a 5 mmol / L PMS solution for later use.

[0087] Step 2: Prepare PFBS solutions of 2 mg / L, 4 mg / L, 5 mg / L, 6 mg / L, and 8 mg / L for later use.

[0088] Step 3: Using 100mL polypropylene centrifuge tubes as reaction vessels, add 20mL of 5mmol / L PMS (i.e., KHSO5) to each of the multiple reaction vessels; add 20mL of PFBS of different concentrations to the above multiple reaction vessels, corresponding to 2mg / L, 4mg / L, 5mg / L, 6mg / L, and 8mg / L respectively; add 0.05g CNF-1 to each of the above multiple reaction vessels.

[0089] Step 4: Place the above reaction vessels in a constant temperature shaker at 180 rpm and carry out the reaction at room temperature (25°C) and pH (5), and take samples at fixed points for analysis.

[0090] The removal rates of PFBS at different PFBS concentrations are shown in Table 4.

[0091] Time (min) Removal % (2.00) Removal % (4.00) Removal % (5.00) Removal % (6.00) Removal % (8.00) 0 0.00 0.00 0.00 0.00 0.00 5 56.74 50.96 51.23 47.02 43.53 15 76.55 69.48 59.88 55.20 50.98 30 78.55 70.09 61.13 57.18 51.40 45 79.49 69.68 60.28 56.86 50.58 60 79.90 69.02 61.42 55.09 52.12

[0092] As shown in the above experimental steps and Table 4, the removal rate of PFBS gradually decreases with increasing PFBS concentration. The degradation rate reaches its maximum of 79.90% when the PFBS concentration is 2 mg / L. Considering both reaction efficiency and cost, a PFBS concentration of 2 mg / L is the optimal choice.

[0093] Experiment 5 compares the effects of different pH values ​​on the catalytic activation of PMS in the degradation of PFBS.

[0094] Step 1: Prepare a 5 mmol / L PMS solution for later use.

[0095] Step 2: Prepare a 2 mg / L PFBS solution for later use.

[0096] Step 3: Using 100mL polypropylene centrifuge tubes as reaction vessels, add 20mL each of 5mmol / L PMS and 2mg / L PFBS to multiple reaction vessels.

[0097] The above reaction vessels were adjusted to different pH values, corresponding to 3, 5, 7, 9, and 11 respectively; 0.05g CNF-1 was added to each of the above reaction vessels.

[0098] Step 4: Place the above reaction vessels in a constant temperature shaker at 180 rpm and carry out the reaction at room temperature (25°C). Take samples at fixed points for analysis.

[0099] Time (min) Removal % (pH=3) Removal % (pH=5) Removal % (pH=7) Removal % (pH=9) Removal % (pH=11) 0 0.00 0.00 0.00 0.00 0.00 5 67.64 56.74 50.79 45.07 39.23 15 82.26 76.55 69.10 65.22 55.19 30 83.03 78.55 71.20 66.38 57.24 45 83.57 79.49 71.85 64.86 53.81 60 85.49 79.90 70.63 67.01 57.72

[0100] Based on the above experimental steps and Table 5, we can conclude that:

[0101] As pH increases, the degradation efficiency of PFBS decreases to varying degrees, but at pH 11, the degradation rate remains above 50%. This indicates that CNF-1 can effectively activate PMS over a wide pH range (3-11), and acidic conditions are more conducive to CNF-1 activating PMS to generate free radicals that degrade PFBS. Therefore, CNF-1 catalytic activation of PMS can effectively remove PFBS under a wide pH range of 3-11.

[0102] Experiment 6 compares the effects of different temperatures on the degradation of PFBS by catalytically activated PMS.

[0103] Step 1: Prepare a 5 mmol / L KHSO5 solution for later use.

[0104] Step 2: Prepare a 2 mg / L PFBS solution for later use.

[0105] Step 3: Using 100mL polypropylene centrifuge tubes as reaction vessels, add 20mL each of 5mmol / L PMS (i.e., KHSO5) and 2mg / L PFBS (i.e., perfluorobutane sulfonic acid) to multiple reaction vessels; add 0.05g CNF-1 to each of the above multiple reaction vessels.

[0106] Step 4: Place the above-mentioned multiple reaction vessels in a constant temperature shaker at 180 rpm. The multiple reaction vessels are reacted at temperatures of 25℃, 35℃, and 45℃, and at pH=3, respectively. Samples are taken at fixed points for analysis.

[0107] The removal rates of PFBS at different temperatures are shown in Table 6.

[0108] Time (min) Removal % (25°C) Removal % (35°C) Removal % (45°C) 0 0.00 0.00 0.00 5 67.64 68.93 85.84 15 82.26 90.30 97.15 30 83.03 91.62 100.00 45 83.57 90.59 100.00 60 85.49 91.77 100.00

[0109] As shown in the above experimental steps and Table 6, increasing the temperature can significantly improve the degradation of PFBS. At a temperature of 45℃, PFBS reaches complete degradation within 30 minutes.

[0110] Experiment 7: This example compares the recycling of CNF-1-catalyzed activation of PMS for PFBS degradation.

[0111] Experiment 1 compares the effects of different systems on the degradation of PFBS by catalytically activated PMS.

[0112] Step 1: Prepare a 5 mmol / L KHSO5 solution for later use.

[0113] Step 2: Prepare a 2 mg / L PFBS solution for later use.

[0114] Step 3: Using 100mL polypropylene centrifuge tubes as reaction vessels, add 20mL each of 5mmol / L PMS and 2mg / L PFBS to multiple reaction vessels; add 0.05g CNF-1 to the above reaction vessels sequentially.

[0115] Step 4: Place the above reaction vessel in a constant temperature shaker at 180 rpm and carry out the reaction at 45°C and pH=3, and take samples at fixed points for analysis.

[0116] Step 5: Filter CNF-1 in the reaction solution from step 4 using a 0.22 μm filter membrane, wash three times each with ultrapure water and anhydrous ethanol, dry, and then add it to a centrifuge tube reaction vessel. Other conditions are the same as in step 4.

[0117] Step 6: Filter CNF-1 in the reaction solution from step 5 using a 0.22µm filter membrane. Wash the solution three times each with ultrapure water and anhydrous ethanol, and then dry it. Add the solution to a centrifuge tube reaction vessel. Other conditions are the same as in step 4.

[0118] Step 7: Filter CNF-1 in the reaction solution from step 6 using a 0.22 μm filter membrane, wash three times each with ultrapure water and anhydrous ethanol, dry, and then add it to a centrifuge tube reaction vessel. Other conditions are the same as in step 4.

[0119] Step 8: Filter CNF-1 in the reaction solution from step 7 using a 0.22 μm filter membrane, wash three times each with ultrapure water and anhydrous ethanol, dry, and then add it to a centrifuge tube reaction vessel. Other conditions are the same as in step 4.

[0120] The PFBS removal rates obtained after 5 cycles are shown in Table 7.

[0121] Time (min) Removal % (1 time) Removal % (2 times) Removal % (3 times) Removal % (4 times) Removal % (5 times) 0 0.00 0.00 0.00 0.00 0.00 5 85.84 81.23 75.38 60.57 48.63 15 97.15 95.67 89.47 75.34 61.79 30 100.00 96.42 90.24 76.48 62.54 45 100.00 95.83 89.76 75.86 61.87 60 100.00 96.25 90.13 76.32 62.17

[0122] Based on the above experimental steps and Table 7, we can conclude that:

[0123] In the cyclic degradation experiments of PFBS by CNF-1 catalyzed activation of PMS, it was clearly observed that the removal rate of PFBS decreased with increasing cycle number. Overall, even after 5 cycles, the degradation efficiency of CNF-1 for PFBS remained above 60.0%, indicating that CNF-1 possesses good in-situ recovery performance. Therefore, the CNF-1 catalyst can still effectively catalyze the degradation of PFBS by activating PMS after multiple cycles.

[0124] This invention employs a preparation method under normal pressure, which requires minimal synthesis equipment. The material possesses numerous unsaturated metal active centers, enhancing the effect of PS in generating sulfate free radicals and resulting in excellent pollutant removal. The catalyst of this invention can be repeatedly recycled, making it environmentally friendly and free from secondary pollution. The catalyst of this invention is applicable to a wide pH range. The method of this invention does not require additional energy consumption, including ultrasound, light, and electricity, thus reducing costs. Moreover, the process is very simple, highly operable, durable, and has a short catalytic time.

[0125] Note: In this embodiment, all concentration dilution issues are calculated according to the formula C1V1=C2V2. For example, mixing 20 mL of 4 mg / L PFBS solution and 20 mL of 2 mmol / L PMS solution will result in final concentrations of 2 mg / L and 1 mmol / L, respectively. All concentrations mentioned herein are the actual concentrations of the final solutions.

[0126] Note: This application actually uses the "in-situ co-synthetic doping" method. In this process, when some divalent metal ions (Cu) 2+ / Ni 2+ ) enters the original trivalent iron (Fe) 3+ When the lattice sites of H0 are located, the lattice of the formed material maintains overall electroneutrality through a spontaneous proton compensation mechanism. Specifically, the protons (H0) provided by the reaction system... + The ions will directly bond to the metal cluster nodes in the form of hydroxyl groups (-OH) or coordinated water, neutralizing local charges. Therefore, the doping method does not lead to a charge imbalance in the final material.

[0127] Special notes are as follows:

[0128] Point 1: Calculation and design basis for the molar ratio of metal to fumaric acid.

[0129] 1. Pure MIL-88A (Fe) scheme: Fumaric acid dosage 4.4800g, moles = 4.4800g / 116g / mol ≈ 0.0386mol; Fe 3+The molar number is approximately 11.2528 g / 270.3 g / mol, which is approximately 0.0416 mol. The molar ratio of metal to fumaric acid is approximately 0.0416:0.0386, which is approximately 1.078:1. This is highly consistent with the theoretical ratio of 1:1 for traditional MIL-88A (Fe), and pure-phase MIL-88A (Fe) substrate materials can be stably synthesized.

[0130] 2. Cu doping scheme: The molar amount of fumaric acid remains 0.0386 mol; the total amount of metal ions = Cu 2+ (7.1456g / 170.48g / mol≈0.0419mol)+Fe 3+ (0.0416 mol) ≈ 0.0835 mol. The molar ratio of metal to fumaric acid is approximately 0.0835:0.0386 ≈ 2.16:1. This scheme, through a Cu:Fe = 1:1 doping design, aims to construct Fe-Cu dual redox centers to enhance the catalytic activity of the material, which is in line with the conventional design logic of functionalized doping of MOF materials.

[0131] 3. Cu and Ni co-doping scheme: Molar amount of fumaric acid = 4.4800g / 116g / mol ≈ 0.0386mol; Total amount of metal ions = Cu 2+ (0.0419mol) + Fe 3+ (0.0416 mol) + Ni 2+ (13.1250g / 290.8g / mol≈0.0451mol)≈0.1286mol, the molar ratio of metal to fumaric acid≈0.1286:0.0386≈3.33:1. By adjusting the pore structure and surface electron distribution of MIL-88A(Fe) through Ni doping, the stability of the material and the adsorption selectivity of the target pollutant are simultaneously improved. Furthermore, characterization experiments confirm that excess metal can be effectively doped through system regulation.

[0132] Secondly, the synthesis system will suppress the generation of impurity phases and ensure coordination-guided assembly.

[0133] 1. In each scheme, solutions A and B are ultrasonically dispersed for 1 hour to prevent local aggregation of metal ions and avoid hydrolysis caused by excessively high local metal ion concentrations. At the same time, heating to 70°C to dissolve fumaric acid (solution A) can enhance its dissociation degree and increase the effective concentration of carboxyl coordination sites, laying the foundation for sufficient coordination with metal ions in the subsequent process.

[0134] 2. Fumaric acid is a diprotic weak acid (pKa1≈3.03, pKa2≈4.44), and forms a weakly acidic solution upon dissolution (in this application, the concentration of fumaric acid is approximately 0.06 mol / L, and the solution pH is approximately 3.5-4.0). Within this pH range, the hydrolysis equilibrium of Fe³⁺, Cu²⁺, and Ni²⁺ is significantly suppressed (Ksp of Fe(OH)₃≈2.79×10⁻⁶). -39 Cu(OH)₂≈2.2×10 -20 Ni(OH)2≈5.5×10 -16 In a weakly acidic environment, the concentration of OH⁻ is extremely low, which cannot reach the precipitation solubility product of hydroxides, thus reducing the possibility of hydroxide impurity phase formation at the source.

[0135] 3.110℃ hydrothermal environment can significantly enhance the coordination activity of fumarate carboxyl groups with metal ions, promoting the directional growth of characteristic crystalline phases of MIL-88A(Fe). The crystal structure of MIL-88A(Fe) has "lattice defect tolerance". Excess Cu²+ and Ni²+ can preferentially occupy the lattice sites of Fe³+ through the "doping site competition" mechanism (the ionic radii of Cu²+ and Ni²+ are close to those of Fe³+, 0.073nm, 0.069nm, and 0.064nm, respectively), thus achieving doping modification. This process is dominated by "coordination-guided crystalline phase growth".

[0136] Thirdly, effective washing.

[0137] 1. The weakly acidic environment has suppressed the formation of hydroxide precipitates. Excess metal ions preferentially participate in the doping of the MIL-88A (Fe) lattice and will not form co-precipitable hydroxides or amorphous impurity phases. The small amount of uncoordinated metal ions that may exist in the system are in a free state.

[0138] 2. After the reaction, the system mainly consists of two parts: (1) Solid phase: well-crystallized, phase-pure (Cu,Ni)-doped MIL-88A (Fe) nanorods, whose internal metal / ligand ratio strictly conforms to crystallographic stoichiometry. (2) Liquid phase: containing a large amount of uncoordinated excess metal ions (Fe). 3+ Cu 2+ Ni 2+ The reaction mother liquor containing a small amount of free ligands is also included. The washing steps (water washing / ethanol washing-centrifugation) have the scientific purpose and practical function of thoroughly removing soluble metal ions and other soluble impurities adsorbed on the surface of MOF particles and mixed in the precipitate by repeatedly replacing the liquid phase.

[0139] Point 4: Characterization experiments to verify the basis.

[0140] 1. Scanning electron microscopy (SEM) images further verified the uniformity of the product morphology on a macroscopic scale. All products were regular nanorod structures, without any irregular blocky or flocculent impurities (typical morphology of hydroxides). Furthermore, there was no adhesion of impurity particles between the nanorods, and the product as a whole was a single phase.

[0141] 2. X-ray diffraction (XRD) characterization: The XRD patterns of Cu-doped and Cu-Ni co-doped products showed no significant difference from the standard pattern of pure MIL-88A(Fe). The characteristic diffraction peaks were sharp, intense, and without any shift, indicating good crystallinity. Crucially, the patterns did not show characteristic diffraction peaks of hydroxide impurity phases such as Fe(OH)3 (2θ=20.2°, 33.3°), Cu(OH)2 (2θ=16.7°, 23.8°), and Ni(OH)2 (2θ=33.9°, 59.4°), nor did they show any other coordination polymer impurity peaks that were not MIL-88A(Fe) structures. Therefore, the product is a single MIL-88A(Fe) crystal phase.

Claims

1. The application of a Cu / Ni doped modified MIL-88A material in the degradation of PFBS by activated potassium persulfate, characterized in that, Includes the following steps: S1, prepare a 1-10 mmol / L PMS solution for later use; S2, prepare a 2-8 mg / L PFBS solution for later use; S3, using 100mL polypropylene centrifuge tubes as reaction vessels, add 20mL each of 1-10mmol / L PMS and 2-8mg / L PFBS to the reaction vessel; add 0.01-0.1g of Cu and Ni doped modified MIL-88A material to the above reaction vessel; S4. Place the above reaction vessel in a constant temperature shaker at 180 rpm and carry out the reaction at 25-45℃ and pH=3-11. Take samples at fixed points for analysis. The preparation of the Cu and Ni doped modified MIL-88A material includes the following steps: (1) Dissolve 4.4800g of fumaric acid at 70℃ and obtain solution A in 640mL of ultrapure water; (2) Take 7.1456g of CuCl2·2H2O, 11.2528g of FeCl3·6H2O, and 13.1250g of Ni(NO3)2·6H2O, mix and dissolve them in 160mL of ultrapure water at room temperature to obtain solution B; (3) Mix solution A from step 1 and solution B from step 2 thoroughly, and heat at 100-120℃ and 1000-1200 r·min -1 Stir for 5-6 hours under the specified conditions; (4) After the reaction is completed and cooled, the precipitate is washed by centrifugation with ultrapure water and anhydrous ethanol. The washing standard is to wash until the ultrapure water and anhydrous ethanol are clear. The precipitate is dried overnight at 60-80℃. After drying, the obtained solid is ground and then sieved through a 60-mesh standard sieve. The sieve-undersized product is collected, and finally, Cu and Ni doped modified MIL-88A material with uniform particle size is obtained.

2. The application of the Cu and Ni doped modified MIL-88A material according to claim 1 in the degradation of PFBS by activated potassium persulfate, characterized in that: Prepare a 5 mmol / L PMS solution in S1.

3. The application of the Cu and Ni doped modified MIL-88A material according to claim 1 in the degradation of PFBS by activated potassium persulfate, characterized in that: Prepare a 2 mg / L PFBS solution in S2.

4. The application of the Cu and Ni doped modified MIL-88A material according to claim 1 in the degradation of PFBS by activated potassium persulfate, characterized in that: 0.05g of Cu and Ni-doped modified MIL-88A material was added to S3.

5. The application of the Cu and Ni doped modified MIL-88A material according to claim 1 in the degradation of PFBS by activated potassium persulfate, characterized in that: The reaction in S4 was carried out at 45°C and pH=3.

6. The application of the Cu and Ni doped modified MIL-88A material according to claim 1 in the degradation of PFBS by activated potassium persulfate, characterized in that: In step (1), when fumaric acid is dissolved in 640 mL of ultrapure water, it is ultrasonically dispersed for 1 hour using an ultrasonic cleaner.

7. The application of the Cu and Ni doped modified MIL-88A material according to claim 1 in the degradation of PFBS by activated potassium persulfate, characterized in that: In step (2), when CuCl2·2H2O, FeCl3·6H2O, and Ni(NO3)2·6H2O are dissolved in 160mL of ultrapure water, they are ultrasonically dispersed for 1h using an ultrasonic cleaner.

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