A method for degrading organic pollutants by using cobalt-doped MIL-88 to activate persulfate
By loading cobalt onto the surface of MIL-88 using a solvothermal method, a cobalt-doped MIL-88 catalyst was prepared, which solved the problems of uneven cobalt doping and insufficient exposure of active sites, and achieved the effect of efficient degradation of organic pollutants.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HUNAN UNIV
- Filing Date
- 2025-04-24
- Publication Date
- 2026-07-21
AI Technical Summary
Existing cobalt-doped MIL-88 materials suffer from uneven cobalt doping and limited exposure of active sites, resulting in poor persulfate activation and difficulty in efficiently degrading organic pollutants.
Cobalt was loaded onto the surface of MIL-88 using a solvothermal method. By controlling the ratio of ethanol and water in the mixed solution and the reaction conditions, cobalt-doped MIL-88 was prepared and used as a persulfate catalyst. The synergistic effect of cobalt and iron was utilized to improve the catalytic activity.
We have achieved cobalt-doped MIL-88 with good catalytic activity, high degradation efficiency, and good stability. It can efficiently remove organic pollutants in water, especially sulfadiazine, tetracycline, and carbamazepine, with a degradation rate of over 90%.
Smart Images
Figure CN120518200B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of water treatment technology, specifically relating to a method for degrading organic pollutants using cobalt-doped MIL-88 to activate persulfate. Background Technology
[0002] With the advancement of chemical technology, environmental pollution problems are becoming increasingly prominent, especially the emergence of new pollutants, which are placing greater pressure on ecological and environmental protection. Among these, the emission of organic pollutants, such as antibiotics, poses a serious threat to ecosystems, while traditional biochemical treatment processes suffer from poor efficiency. Therefore, the removal of organic pollutants has become an urgent problem to be solved in the field of environmental governance. Against this backdrop, advanced oxidation processes based on persulfate, due to their ability to generate highly oxidizing sulfate radicals (SO42-), have emerged as a promising solution. ·- It has gradually emerged as an important technological approach for treating organic pollutants.
[0003] Traditional homogeneous catalysis technology has high removal efficiency, but it contains transition metal ions such as Fe. 2+ or Co 2+ The current methods of catalyst addition involve large quantities, difficult recovery, and the risk of secondary pollution. In contrast, heterogeneous catalysis technology is attracting increasing attention due to the reusability and ease of catalyst recovery. Metal-organic frameworks (MOFs) are a novel type of porous material that has garnered significant attention due to their high specific surface area, tunable pore structure, and excellent adsorption / catalytic capabilities.
[0004] MIL-88, as a representative metal-organic framework, uses inexpensive ferric chloride and carboxylic acid ligands as raw materials, making it an excellent choice for preparing green catalysts. Furthermore, it possesses excellent water stability and has already seen some application in activating persulfate degradation of organic pollutants. However, its performance is limited by the Fe content in its structural units. 3+ MIL-88's weak catalytic properties and electron transfer inertness result in poor ability to activate persulfates. Therefore, it is usually necessary to modify MIL-88 to use it as a support for new catalytic sites or to undergo derivatization to change its characteristic structure.
[0005] Cobalt, as a heavy metal element, has attracted much attention due to its strong activity in persulfate catalysis. In recent years, the strategy of combining cobalt with MOFs to form functionalized composite materials has gradually gained favor among researchers. Such doped materials not only retain the high specific surface area and excellent structural properties of MOFs, but also significantly improve catalytic activity through the introduction of cobalt. However, in previous studies, the inventors of this application found that cobalt-doped MOF materials prepared by existing methods often suffer from problems such as uneven cobalt doping, limited exposure of active sites, poor persulfate activation, and poor degradation. Therefore, there is an urgent need to find a method for preparing cobalt-doped MIL-88 to obtain cobalt-doped MIL-88 with good catalytic activity and high degradation efficiency, thereby achieving efficient degradation of organic pollutants. Summary of the Invention
[0006] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a method for degrading organic pollutants by activating persulfate with cobalt-doped MIL-88, which has good catalytic activity, high degradation efficiency, good removal effect and good stability.
[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution.
[0008] A method for degrading organic pollutants using cobalt-doped MIL-88-activated persulfate, wherein the method utilizes cobalt-doped MIL-88-activated persulfate to degrade water containing organic pollutants; the preparation method of cobalt-doped MIL-88 includes the following steps: mixing a mixed solution of MIL-88, cobalt salt, ethanol, and water, and carrying out a solvothermal reaction to obtain cobalt-doped MIL-88; wherein the volume fraction of ethanol in the mixed solution of ethanol and water is 80%–90%.
[0009] In a further improvement to the above method, the mass ratio of MIL-88 to cobalt salt is 1:2 to 3, the mass-volume ratio of the mixed solution of MIL-88, ethanol and water is 4 mg to 6 mg: 1 mL, and the cobalt salt is at least one of cobalt nitrate, cobalt chloride and cobalt sulfate.
[0010] In a further improvement to the above method, the temperature of the solvothermal reaction is 110℃~120℃, and the time of the solvothermal reaction is 5h~7h.
[0011] The above method is further improved, and the preparation method of MIL-88 includes the following steps: mixing organic ligands, iron salts and water, and reacting at 90℃~110℃ to obtain MIL-88; the molar ratio of the organic ligands to the iron salts is 1~2∶1.
[0012] In a further improvement to the above method, the organic ligand is at least one of fumaric acid, terephthalic acid, 2,6-naphthoic acid, and 4,4'-biphenyl dicarboxylic acid, and the iron salt is ferric chloride.
[0013] The above method is further improved in that the reaction time is 2h to 3h, the mixing is carried out under ultrasonic conditions, the ultrasonic time is 5min to 15min, and the reaction is further improved by drying the reaction product.
[0014] In a further improvement to the above method, the degradation treatment specifically involves mixing cobalt-doped MIL-88 with water containing organic pollutants, adding persulfate, and carrying out a degradation reaction to achieve the degradation of organic pollutants in the water.
[0015] In a further improvement to the above method, the amount of cobalt-doped MIL-88 added is 0.15g to 0.2g per liter of water containing organic pollutants.
[0016] In a further improvement to the above method, the amount of persulfate added is 0.4 mmol to 0.5 mmol per liter of water containing organic pollutants, wherein the persulfate is permonosulfate and the permonosulfate is potassium peroxymonosulfate.
[0017] In a further improvement to the above method, the initial concentration of organic pollutants in the water containing organic pollutants is 10 mg / L to 20 mg / L, the pH value of the water containing organic pollutants is 3 to 11, the organic pollutants in the water containing organic pollutants include at least one of sulfadiazine, tetracycline, ciprofloxacin and carbamazepine, and the degradation reaction time is ≥5 min.
[0018] Compared with the prior art, the innovation and advantages of this invention are as follows:
[0019] This invention proposes a method for degrading organic pollutants using cobalt-doped MIL-88 activated persulfate. Figure 1 The cobalt-doped MIL-88 is prepared by a solvothermal reaction using MIL-88 and cobalt salt as raw materials and a mixed solution of ethanol and water as solvent. The cobalt-doped MIL-88 used in this invention has the following advantages:
[0020] First, this invention addresses the problems of uneven metal doping and limited exposure of active sites in existing metal-doped MOF materials. It proposes a method of synthesizing the MOF first and then thermally doping it in solution, achieving concentrated doping modification of the MOF surface. This invention utilizes the swelling properties of MIL-88, thermally reacting it in a mixed polar solvent to concentrate cobalt on the MIL-88 surface, avoiding the problem of doped metals being buried inside the MOF and not effectively exposed. The synthesis method of this invention is simple; the subsequent synthesis process, apart from the polar solvent and cobalt dopant, requires no additional reagents for adjustment or treatment. When cobalt is loaded on the MIL-88 surface, it acts as a catalytic site for persulfate, activating the persulfate to generate surface-bound free radicals. These free radicals are confined to the catalyst surface to oxidize organic pollutants, reducing mass transfer loss in water and prolonging the reaction time of the free radicals, thereby achieving efficient removal of organic pollutants.
[0021] Secondly, this invention adjusts the doping ratio by limiting the amount of cobalt added, and further precisely controls the cobalt doping density on the surface of MIL-88 to >2.5 at by limiting the volume fraction of ethanol in the mixed solution of ethanol and water to 80% to 90%. This avoids the problem of surface saturation and resource waste caused by relying solely on excessive cobalt addition, and allows cobalt-doped MIL-88 to expose more active sites, improving its activation ability for persulfate and thus improving the removal efficiency of organic pollutants.
[0022] Third, cobalt doping exists in a bound state at the MIL-88 framework nodes, rather than in a reduced elemental state. This allows for close bonding with iron sites through the organic framework, promoting the conversion of ferric iron to ferrous iron to maximize catalytic performance. This enables the utilization of iron that was originally catalytically inert in MIL-88 during persulfate activation. Simultaneously, the synergistic effect of the cobalt-iron bimetallic combination enhances catalyst stability and extends catalyst lifespan. When applied to membrane reactors, it can achieve stable removal of organic pollutants during long-term operation (>8 hours). For example, sulfadiazine achieved a degradation efficiency of >95% after 8 hours of catalytic oxidation in a membrane reactor.
[0023] Fourth, this invention provides a method for degrading organic pollutants using cobalt-doped MIL-88 activated persulfate. By mixing cobalt-doped MIL-88 with organic pollutants and then adding persulfate for degradation, effective removal of organic pollutants from water can be achieved. This method has the advantages of simple operation and low dosage of catalyst (0.15–0.2 g / L) and oxidant (0.4–0.5 mM), showing promising application prospects. Furthermore, it exhibits excellent catalytic performance and versatility, achieving highly efficient removal of various organic pollutants within a short time of 30 minutes, such as sulfadiazine, tetracycline, ciprofloxacin, and carbamazepine, with removal rates all exceeding 90%.
[0024] The method of the present invention has the advantages of good catalytic activity, high degradation efficiency, good removal effect, good stability, and low dosage of catalyst and oxidant. Attached Figure Description
[0025] Figure 1 This is a schematic diagram of the method route for degrading organic pollutants using cobalt-doped MIL-88 to activate persulfate.
[0026] Figure 2 This is a SEM image of the cobalt-doped MIL-88 obtained in Example 1 of the present invention.
[0027] Figure 3 This is an XPS image of cobalt-doped MIL-88 prepared in Example 1 of the present invention.
[0028] Figure 4 The graphs show the degradation effects of different catalysts on sulfadimethylpyrimidine in Examples 1 to 4 and Comparative Examples 1 to 3 of this invention.
[0029] Figure 5 This is an EPR detection image of reactive oxygen species in the reaction system for the degradation of organic pollutants by persulfate using cobalt-doped MIL-88 in Example 1 of the present invention.
[0030] Figure 6 This is a graph showing the change in the content of divalent iron in the reaction system of persulfate degradation of organic pollutants using cobalt-doped MIL-88 activated by Example 1 of the present invention.
[0031] Figure 7 This is a graph showing the degradation effect of cobalt-doped MIL-88 as a membrane-supported catalyst on sulfadimethylpyrimidine in Example 5 of the present invention. Detailed Implementation
[0032] The present invention will be further described below with reference to the accompanying drawings and specific preferred embodiments, but this does not limit the scope of protection of the present invention. All materials and instruments used in the following embodiments are commercially available.
[0033] Example 1:
[0034] The present invention discloses a method for degrading organic pollutants using cobalt-doped MIL-88-activated persulfate, specifically involving the degradation treatment of water containing sulfadiazine (SMT) using cobalt-doped MIL-88-activated persulfate. Figure 1 As shown, it includes the following steps:
[0035] 100 mL of sulfadiazine solution with a concentration of 40 μM and an initial pH of 5.6 was placed in a cup reactor. 0.015 g of cobalt-doped MIL-88 was added and mixed for 1 min. Then, 1 mL of potassium persulfate (PMS) solution with a concentration of 0.04 M was added and the degradation reaction was carried out for 30 min to achieve the degradation of sulfadiazine in water.
[0036] In this embodiment, the preparation method of cobalt-doped MIL-88 includes the following steps:
[0037] (1) Dissolve 0.2 mol of fumaric acid ligand in 100 mL of water to obtain fumaric acid solution; dissolve 0.2 mol of ferric chloride in 100 mL of water to obtain ferric chloride solution; mix fumaric acid solution and ferric chloride solution, sonicate for 10 min to mix, and react in an oil bath at 100℃ for 2 h. After the reaction is complete, centrifuge to separate the solid, dry and grind at 60℃ to obtain MIL-88.
[0038] (2) Add 250 mg of MIL-88 obtained in step (1) to a mixed solution of 50 mL of ethanol and water, wherein the volume fraction of ethanol in the mixed solution of ethanol and water is 80%, and then add 582 mg of cobalt nitrate, stir and disperse, transfer to a stainless steel reactor with a polytetrafluoroethylene liner, and react with solvent at 120 °C for 6 h. After the reaction is completed, filter with a 0.22 μm organic filter membrane, dry the reaction product at 60 °C, grind it, and obtain cobalt-doped MIL-88, which is denoted as Co-MIL-88A.
[0039] Figure 2 This is a SEM image of the cobalt-doped MIL-88 obtained in Example 1 of this invention. Figure 2 As can be seen, the cobalt-doped MIL-88A of the present invention exhibits a regular needle-like morphology, with a length of 2 μm and a width of about 0.5 μm, and has protrusions on its surface.
[0040] Figure 3 This is an XPS image of cobalt-doped MIL-88 prepared in Example 1 of the present invention. Figure 3 In the diagram, (a) represents Co 2p, and (b) represents O 1s. From... Figure 3 As can be seen, the XPS spectrum successfully detected Co, proving the successful doping of cobalt; at the same time, cobalt replaced the iron sites and combined with the organic ligands in the MIL-88 framework to form cobalt-oxygen bonds.
[0041] SMT concentration was determined using an Agilent 1260 high-performance liquid chromatograph. The analytical conditions were: Agilent EC-C18 column (4.6 × 150 mm, 4 μm), column temperature 30 °C, mobile phase 0.1 wt% formic acid and acetonitrile (80 / 20) mixture, flow rate 1 mL / min, and injection volume 20 μL. Samples were taken at 2, 4, 6, 10, 20, and 30 min to determine the corresponding SMT concentration. The concentration was calculated using the pseudo-first-order kinetic formula kt = -ln(C). t / C0) where k is the degradation rate constant, in min -1 C t SMT concentration at different times (see) Figure 4 C0 represents the initial SMT concentration, and t represents the corresponding treatment time in minutes. Using the above detection data and formulas, the degradation process is kinetically fitted, and the slope k value is obtained as the degradation rate constant of SMT (see Table 1).
[0042] In this embodiment, cobalt-doped MIL-88 showed a degradation rate of 96.93% for sulfadimethylpyrimidine, with a degradation rate of 0.129 min. -1 .
[0043] Example 2:
[0044] A method for degrading organic pollutants using cobalt-doped MIL-88 activated persulfate according to the present invention specifically involves using cobalt-doped MIL-88 to activate persulfate for the degradation treatment of water containing sulfadiazine, comprising the following steps:
[0045] 100 mL of sulfadiazine solution with a concentration of 40 μM and an initial pH of 5.6 was placed in a cup reactor. 0.015 g of cobalt-doped MIL-88 was added and mixed for 1 min. Then, 1 mL of potassium persulfate (PMS) solution with a concentration of 0.04 M was added and the degradation reaction was carried out for 30 min to achieve the degradation of sulfadiazine in water.
[0046] The cobalt-doped MIL-88 used in this embodiment is prepared in a method that is basically the same as the cobalt-doped MIL-88 prepared in Example 1. The only difference is that in step (2), the volume fraction of ethanol in the mixed solution of ethanol and water is 90%.
[0047] In this embodiment, cobalt-doped MIL-88 exhibited a degradation rate of 93.33% for sulfadimethylpyrimidine, with a degradation rate of 0.120 min. -1 .
[0048] Example 3:
[0049] A method for degrading organic pollutants using cobalt-doped MIL-88 activated persulfate according to the present invention specifically involves using cobalt-doped MIL-88 to activate persulfate for the degradation treatment of water containing sulfadiazine, comprising the following steps:
[0050] 100 mL of sulfadiazine solution with a concentration of 40 μM and an initial pH of 5.6 was placed in a cup reactor. 0.015 g of cobalt-doped MIL-88 was added and mixed for 1 min. Then, 1 mL of potassium persulfate (PMS) solution with a concentration of 0.04 M was added and the degradation reaction was carried out for 30 min to achieve the degradation of sulfadiazine in water.
[0051] The cobalt-doped MIL-88 used in this embodiment is prepared in a method that is basically the same as that of cobalt-doped MIL-88 in Example 1. The only difference is that in step (2), the temperature of the solvothermal reaction is 110°C.
[0052] In this embodiment, cobalt-doped MIL-88 showed a degradation rate of 98.61% for sulfadimethylpyrimidine, with a degradation rate of 0.187 min. -1 .
[0053] Example 4:
[0054] A method for degrading organic pollutants using cobalt-doped MIL-88 activated persulfate according to the present invention specifically involves using cobalt-doped MIL-88 to activate persulfate for the degradation treatment of water containing sulfadiazine, comprising the following steps:
[0055] 100 mL of sulfadiazine solution with a concentration of 40 μM and an initial pH of 5.6 was placed in a cup reactor. 0.02 g of cobalt-doped MIL-88 was added and mixed for 1 min. Then, 1 mL of potassium persulfate (PMS) solution with a concentration of 0.04 M was added and the degradation reaction was carried out for 30 min to achieve the degradation of sulfadiazine in water.
[0056] The cobalt-doped MIL-88 used in this embodiment is the same as the cobalt-doped MIL-88 prepared in Example 1.
[0057] In this embodiment, cobalt-doped MIL-88 showed a degradation rate of 97.33% for sulfadimethylpyrimidine, with a degradation rate of 0.163 min. -1 .
[0058] Comparative Example 1:
[0059] A method for degrading organic pollutants using MIL-88 activated persulfate includes the following steps:
[0060] 100 mL of sulfadimethylpyrimidine solution with a concentration of 40 μM and an initial pH of 5.6 was placed in a cup reactor. 0.015 g of MIL-88 was added and mixed for 1 min. Then, 1 mL of potassium persulfate (PMS) solution with a concentration of 0.04 M was added and the degradation reaction was carried out for 30 min to achieve the degradation of sulfadimethylpyrimidine in the water.
[0061] The MIL-88 used in Comparative Example 1 is the same as the MIL-88 used in Example 1.
[0062] In Comparative Example 1, MIL-88 showed a degradation rate of 13.92% for sulfadimethylpyrimidine, with a degradation rate of 0.006 min. -1 .
[0063] Comparative Example 2:
[0064] A method for degrading organic pollutants using cobalt-doped MIL-88A catalyst activated by persulfate includes the following steps:
[0065] 100 mL of sulfadiazine solution with a concentration of 40 μM and an initial pH of 5.6 was placed in a cup reactor. 0.015 g of cobalt-doped MIL-88A catalyst was added and mixed for 1 min. Then, 1 mL of potassium persulfate (PMS) solution with a concentration of 0.04 M was added and the degradation reaction was carried out for 30 min to achieve the degradation of sulfadiazine in water.
[0066] In Comparative Example 2, the preparation method of the cobalt-doped MIL-88A catalyst includes the following steps:
[0067] 0.2 mol of fumaric acid ligand was dissolved in 100 mL of water to obtain a fumaric acid solution; 0.1 mol of ferric chloride and 0.1 mol of cobalt nitrate were dissolved in 100 mL of water to obtain a mixed solution; the fumaric acid solution and the mixed solution were mixed and sonicated for 10 min to achieve homogeneity, and then reacted in an oil bath at 100 °C for 2 h. After the reaction was completed, the solid was separated by centrifugation, dried and ground at 60 °C to obtain the cobalt-doped MIL-88A catalyst.
[0068] In Comparative Example 2, the cobalt-doped MIL-88A catalyst showed a degradation rate of 47.11% for sulfadimethylpyrimidine, with a degradation rate of 0.020 min. -1 .
[0069] Comparative Example 3:
[0070] A method for degrading organic pollutants using cobalt-doped MIL-88 activated persulfate includes the following steps:
[0071] 100 mL of sulfadiazine solution with a concentration of 40 μM and an initial pH of 5.6 was placed in a cup reactor. 0.015 g of cobalt-doped MIL-88 was added and mixed for 1 min. Then, 1 mL of potassium persulfate (PMS) solution with a concentration of 0.04 M was added and the degradation reaction was carried out for 30 min to achieve the degradation of sulfadiazine in water.
[0072] The cobalt-doped MIL-88 used in Comparative Example 3 was prepared in a method that was basically the same as that used in Example 1. The only difference was that in step (2), the volume fraction of ethanol in the mixed solution of ethanol and water was 60%.
[0073] In Comparative Example 3, the cobalt-doped MIL-88 exhibited a degradation rate of 72.28% for sulfadimethylpyrimidine, with a degradation rate of 0.051 min. -1 .
[0074] Comparative Example 4:
[0075] A method for degrading organic pollutants using cobalt-doped MIL-88 activated persulfate includes the following steps:
[0076] 100 mL of sulfadiazine solution with a concentration of 40 μM and an initial pH of 5.6 was placed in a cup reactor. 0.015 g of cobalt-doped MIL-88 was added and mixed for 1 min. Then, 1 mL of potassium persulfate (PMS) solution with a concentration of 0.04 M was added and the degradation reaction was carried out for 30 min to achieve the degradation of sulfadiazine in water.
[0077] The cobalt-doped MIL-88 used in Comparative Example 4 was prepared in a method that was basically the same as that used in Example 1. The only difference was that in step (2), pure ethanol was used instead of the mixture of ethanol and water.
[0078] In Comparative Example 4, the cobalt-doped MIL-88 exhibited a degradation rate of 75.66% for sulfadimethylpyrimidine, with a degradation rate of 0.053 min. -1 .
[0079] Table 1. Degradation rates and degradation rates of different catalysts in Examples 1-4 and Comparative Examples 1-4.
[0080]
[0081] Figure 5 This is an EPR (Enhanced Peroxidation Rate) chart of reactive oxygen species in the reaction system for the degradation of organic pollutants using cobalt-doped MIL-88 activated persulfate, as described in Example 1 of this invention. Figure 5It can be seen that the cobalt-doped MIL-88 of this invention can effectively activate persulfate, forming surface-bound free radicals, thereby improving its degradation efficiency for organic pollutants in water. Furthermore, the addition of sodium fluoride to the reaction system promotes the release of surface free radicals, enhancing the EPR signal, which also indirectly proves that the cobalt-doped MIL-88 effectively activates persulfate.
[0082] Figure 6 This is a graph showing the change in the content of divalent iron in the reaction system of persulfate degradation of organic pollutants using cobalt-doped MIL-88 activated by Example 1 of the present invention. Figure 6 In the image, (a) shows the determination of ferrous iron content using the o-phenanthroline spectrophotometric method, and (b) shows the effect of 2,2-bipyridine chelate ferrous iron on SMT degradation. Figure 6 (a) It can be seen that as the degradation reaction proceeds, the Fe in the reaction system... 2+ The content increases, meaning that Fe is continuously converted during the degradation reaction. 2+ As can be seen from 6(b), the addition of 2,2-bipyridine reduces the Fe produced during the degradation reaction. 2+ After chelation, the degradation effect of sulfadimethylpyrimidine decreased significantly, indicating that the catalytic performance of the cobalt-doped MIL-88 catalyst was significantly suppressed. This shows that, compared to the Fe in Comparative Example 1's MIL-88... 3+ Exhibiting low catalytic activity, the cobalt-doped MIL-88 of this invention can, through cobalt doping, enhance the catalytic activity of Fe in MIL-88. 3+ Converted to Fe 2+ This effectively activates persulfate, ultimately improving the degradation rate and efficiency of organic pollutants.
[0083] Example 5:
[0084] A method for degrading organic pollutants using cobalt-doped MIL-88 activated persulfate according to the present invention specifically involves using cobalt-doped MIL-88 to activate persulfate for the degradation of ciprofloxacin in water, comprising the following steps:
[0085] 100 mL of ciprofloxacin (CIP) solution with a concentration of 20 mg / L and an initial pH of 5.2 was placed in a cup reactor. 0.015 g of cobalt-doped MIL-88 was added, and after mixing for 1 min, 1 mL of potassium persulfate (PMS) solution with a concentration of 0.04 M was added. The degradation reaction was carried out for 30 min to achieve the degradation of ciprofloxacin in the water.
[0086] The cobalt-doped MIL-88 used in this embodiment is the same as the cobalt-doped MIL-88 prepared in Example 1.
[0087] In this embodiment, cobalt-doped MIL-88 exhibited a degradation rate of 90.22% for ciprofloxacin, with a degradation rate of 0.101 min. -1 .
[0088] This invention also tested the degradation effect of cobalt-doped MIL-88 as a membrane-supported catalyst on organic pollutants, specifically:
[0089] 50 mg of cobalt-doped MIL-88 prepared in Example 1 was placed on a 0.22 μm aqueous membrane filter (MCE) to obtain a cobalt-doped MIL-88 / MCE membrane. This membrane was then placed in a flow path within a column reactor to construct a continuous flow reactor. An 80 μM sulfadimethylpyrimidine solution and a 0.8 mM potassium persulfate (PMS) solution were simultaneously introduced into the column reactor at a flow rate of 0.5 mL / min (i.e., the concentration of sulfadimethylpyrimidine in the flow reactor reaction system was 40 μM and the concentration of PMS was 0.4 mM). After catalytic filtration through the cobalt-doped MIL-88 / MCE membrane, the degradation of sulfadimethylpyrimidine was achieved. The effluent was collected every 10 min.
[0090] Control group: MIL-88 from Comparative Example 1 was used instead of cobalt-doped MIL-88, with other conditions remaining the same.
[0091] Figure 7 This is a graph showing the degradation effect of cobalt-doped MIL-88 as a membrane-supported catalyst on sulfadimethylpyrimidine in Example 5 of the present invention. Figure 7 In the image, (a) shows a physical image of cobalt-doped MIL-88 supported on a filter membrane, (b) shows a column reactor, (c) shows a continuous flow reactor, and (d) shows the degradation effect of cobalt-doped MIL-88 and MIL-88 as a membrane-supported catalyst on sulfadiazine. Figure 7 It can be seen that after 500 minutes of continuous operation, the degradation rate of sulfadimethylpyrimidine by cobalt-doped MIL-88 as a membrane-supported catalyst can still be maintained at over 98%, while the degradation rate of MIL-88 as a membrane-supported catalyst is only 47%. This indicates that the cobalt-doped MIL-88 of the present invention has better performance in membrane-supported filtration catalysis.
[0092] Compared to traditional one-pot synthesis methods, the cobalt-doped MIL-88 preparation method in this invention, by loading cobalt onto the surface of MIL-88, effectively exposes catalytic sites, thereby facilitating the adsorption and activation of persulfate. Simultaneously, the reactive oxygen species generated on the catalyst surface can rapidly contact organic pollutants, achieving efficient degradation. The cobalt-doped MIL-88 of this invention, through cobalt doping and the synergistic effect of the cobalt-iron bimetallic compound, ensures the continuous and stable generation of free radicals in the degradation reaction system. This not only significantly improves the catalyst's catalytic activation ability for persulfate but also enhances the catalyst's stability during the degradation of organic pollutants.
[0093] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the spirit and technical essence of the present invention. Therefore, any simple modifications, equivalent substitutions, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall still fall within the protection scope of the technical solutions of the present invention.
Claims
1. A method for degrading organic pollutants using cobalt-doped MIL-88 activated persulfate, characterized in that, The method utilizes cobalt-doped MIL-88 to activate persulfate for the degradation of water containing organic pollutants. The preparation method of cobalt-doped MIL-88 includes the following steps: mixing a mixed solution of MIL-88, cobalt salt, ethanol and water, and carrying out a solvothermal reaction to obtain cobalt-doped MIL-88; the volume fraction of ethanol in the mixed solution of ethanol and water is 80% to 90%.
2. The method for degrading organic pollutants using cobalt-doped MIL-88 activated persulfate according to claim 1, characterized in that, The mass ratio of MIL-88 to cobalt salt is 1:2 to 3, and the mass-to-volume ratio of the mixed solution of MIL-88, ethanol and water is 4 mg to 6 mg: 1 mL. The cobalt salt is at least one of cobalt nitrate, cobalt chloride and cobalt sulfate.
3. The method for degrading organic pollutants using cobalt-doped MIL-88 activated persulfate according to claim 2, characterized in that, The temperature of the solvothermal reaction is 110℃~120℃, and the time of the solvothermal reaction is 5h~7h.
4. The method for degrading organic pollutants using cobalt-doped MIL-88 activated persulfate according to claim 3, characterized in that, The preparation method of MIL-88 includes the following steps: mixing an organic ligand, an iron salt, and water, and reacting at 90℃~110℃ to obtain MIL-88; the molar ratio of the organic ligand to the iron salt is 1~2∶1.
5. The method for degrading organic pollutants using cobalt-doped MIL-88 activated persulfate according to claim 4, characterized in that, The organic ligand is at least one of fumaric acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid and 4,4'-biphenyl dicarboxylic acid, and the iron salt is ferric chloride.
6. The method for degrading organic pollutants using cobalt-doped MIL-88 to activate persulfate according to claim 5, characterized in that, In the preparation of MIL-88, the reaction time is 2h to 3h, the mixing is carried out under ultrasonic conditions, the ultrasonic time is 5min to 15min, and the reaction is followed by the following treatment: drying the reaction product.
7. The method for degrading organic pollutants using cobalt-doped MIL-88 activated persulfate according to any one of claims 1 to 6, characterized in that, The degradation treatment specifically involves mixing cobalt-doped MIL-88 with water containing organic pollutants, adding persulfate, and carrying out a degradation reaction to achieve the degradation of organic pollutants in the water.
8. The method for degrading organic pollutants using cobalt-doped MIL-88 to activate persulfate according to claim 7, characterized in that, The amount of cobalt-doped MIL-88 added is 0.15g to 0.2g per liter of water containing organic pollutants.
9. The method for degrading organic pollutants using cobalt-doped MIL-88 activated persulfate according to claim 8, characterized in that, The amount of persulfate added is 0.4 mmol to 0.5 mmol per liter of water containing organic pollutants. The persulfate is potassium peroxymonosulfate.
10. The method for degrading organic pollutants using cobalt-doped MIL-88 activated persulfate according to claim 9, characterized in that, The initial concentration of organic pollutants in the water body containing organic pollutants is 10 mg / L to 20 mg / L, the pH value of the water body containing organic pollutants is 3 to 11, the organic pollutants in the water body containing organic pollutants include at least one of sulfadiazine, tetracycline, ciprofloxacin and carbamazepine, and the degradation reaction time is ≥5 min.