Method for treating antibiotic wastewater by using hydrogel electrode coated with bimetal organic framework derivative

Abstract

The invention discloses a method for treating antibiotic wastewater by using a hydrogel electrode coated with a bimetal organic framework derivative, which is characterized in that the antibiotic wastewater is degraded by using the hydrogel electrode coated with the bimetal organic framework derivative, and the hydrogel electrode coated with the bimetal organic framework derivative takes hydrogel as a substrate; a ferrocobalt bimetal organic framework derivative is loaded on the hydrogel substrate, and the ferrocobalt bimetal organic framework derivative comprises CoFe2O4 and Co3Fe7. The method has the advantages of being good in degradation effect, high in treatment efficiency, good in stability, good in recyclability, low in metal leaching concentration, high in anti-interference capacity and the like, can keep high catalytic activity in wide current density, pH value and antibiotic concentration ranges, and keeps high adaptability in different water environments.

Description

Technical Field

[0001] The invention belongs to the technical field of electro-Fenton cathode preparation, and in particular relates to a method for treating antibiotic wastewater by using a hydrogel electrode wrapped with a bimetallic organic framework derivative. Background Art

[0002] Electro-Fenton technology has been applied to the field of organic pollutant wastewater treatment due to its high efficiency and rapidity, and has attracted widespread attention from researchers. Iron-based materials such as iron-containing minerals, iron-containing layered double hydroxide materials and iron-containing carbon catalysts show great application potential in electro-Fenton technology due to their low energy consumption requirements and high catalytic efficiency. MOFs are materials composed of metal centers and organic ligands, with high specific surface area, abundant active sites and easily adjustable structures, and have shown excellent performance in the field of organic pollutant wastewater treatment. At present, in the treatment of organic pollutant wastewater based on electro-Fenton technology, MOFs materials are usually directly put into the electro-Fenton system as catalysts, or MOFs materials are coated on conductive substrates as electrodes. However, these methods have defects in practical applications, such as the inability to effectively recover the catalyst and the easy detachment of the catalyst from the conductive substrate, which not only affects the catalytic efficiency of the electro-Fenton reaction, but also causes new pollution to the water body. Therefore, there is an urgent need to develop a method for treating antibiotic wastewater using hydrogel electrodes wrapped with bimetallic organic framework derivatives, which has good degradation effect, high treatment efficiency, good stability, good recyclability, low metal leaching concentration, and strong anti-interference ability. Summary of the invention

[0003] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a method for treating antibiotic wastewater by using a hydrogel electrode wrapped with a bimetallic organic framework derivative, which has good degradation effect, high treatment efficiency, good stability, good recyclability, low metal leaching concentration and strong anti-interference ability.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions.

[0005] A method for treating antibiotic wastewater using a hydrogel electrode wrapped with a bimetallic organic framework derivative, wherein the method uses a hydrogel electrode wrapped with a bimetallic organic framework derivative to degrade the antibiotic wastewater; the hydrogel electrode wrapped with a bimetallic organic framework derivative is based on a hydrogel, and a cobalt-iron bimetallic organic framework derivative is loaded on the hydrogel substrate, and the cobalt-iron bimetallic organic framework derivative includes CoFe 2 O 4 and Co 3 Fe 7 .

[0006] The above method is further improved, and the preparation method of the hydrogel electrode wrapped with a bimetallic organic framework derivative comprises the following steps:

[0007] S1, mixing iron salt, cobalt salt, organic ligand and organic solvent, and subjecting to microwave hydrothermal reaction to obtain Co-MIL-88B(Fe);

[0008] S2, calcining the Co-MIL-88B(Fe) obtained in step S1 to obtain a bimetallic organic framework derivative;

[0009] S3, mixing the bimetallic organic framework derivative obtained in step S2 with a mixed aqueous solution containing cellulose and agar, evaporating, adding a crosslinking agent, and performing a crosslinking reaction to obtain a hydrogel electrode wrapped with the bimetallic organic framework derivative.

[0010] The above method is further improved. In step S3, the mass volume ratio of the bimetallic organic framework derivative to the mixed aqueous solution containing cellulose and agar is 40 mg~50 mg: 30 mL~32 mL, the mass ratio of the bimetallic organic framework derivative to the cellulose in the mixed aqueous solution containing cellulose and agar is 0.04~0.05: 19.9~20.1, and the mass ratio of the bimetallic organic framework derivative to the agar in the mixed aqueous solution containing cellulose and agar is 0.4~0.5: 6~7.

[0011] The above method is further improved, in step S3, the cellulose in the mixed aqueous solution containing cellulose and agar is nanocellulose, the crosslinking agent is a sulfuric acid solution and an N,N'-methylenebisacrylamide solution, the mass volume ratio of the bimetallic organic framework derivative, the sulfuric acid solution, and the N,N'-methylenebisacrylamide solution is 40mg-50mg: 4mL-5mL: 4mL-5mL, and the concentration of the sulfuric acid solution is 1mol·L -1 The mass fraction of the N,N'-methylenebisacrylamide solution is 4%; the evaporation temperature is 60°C to 80°C; the evaporation time is 2h to 4h; and the cross-linking reaction time is 2min to 3min.

[0012] The above method is further improved, in step S1, the mass ratio of the iron salt, cobalt salt and organic ligand is 1.8-1.9:0.3-0.4:1.6-1.7, and the mass volume ratio of the iron salt to the organic solvent is 1.8g-1.9g:55mL-60mL.

[0013] The above method is further improved, in step S1, the iron salt is ferric chloride, the cobalt salt is cobalt dichloride, the organic ligand is terephthalic acid, and the organic solvent is N,N-dimethylformamide; the temperature of the microwave hydrothermal reaction is 150°C, the time of the microwave hydrothermal reaction is 40 minutes, the equipment used for the microwave hydrothermal reaction is a microwave hydrothermal synthesizer, and the power of the microwave hydrothermal synthesizer is 1000W; after the microwave hydrothermal reaction, the following treatment is also included: the microwave hydrothermal reaction product is washed with N,N-dimethylformamide and methanol in sequence, and vacuum dried at a temperature of 60°C to 80°C for 8h to 12h.

[0014] The above method is further improved, in step S2, the calcination is carried out in a nitrogen atmosphere, and the heating rate during the calcination is 4°C·min -1 ~6℃·min -1 The calcination temperature is 580°C to 620°C, and the calcination time is 2h to 3h.

[0015] The above method is further improved, and the degradation treatment is: using a hydrogel electrode wrapped with a bimetallic organic framework derivative as a cathode, a platinum sheet as an anode, adding antibiotic wastewater, and performing an electro-Fenton reaction to achieve degradation of the antibiotics in the wastewater.

[0016] The above method is further improved, wherein the initial concentration of the antibiotic in the antibiotic wastewater is 10 mg·L -1 ~30mg·L -1 The antibiotic in the antibiotic wastewater is tetracycline, and the pH value of the antibiotic wastewater is 3-9.

[0017] The above method is further improved, wherein the current density during the electro-Fenton reaction is 3 mA·cm -2 ~10mA·cm -2 The electro-Fenton reaction time is ≥ 60 min; the electro-Fenton reaction process also includes adding electrolytes to the antibiotic wastewater to make the concentration of electrolytes in the reaction system 0.05 mol·L -1 , the electrolyte is sodium sulfate.

[0018] Compared with the prior art, the advantages of the present invention are:

[0019] The present invention discloses a method for treating antibiotic wastewater by using a hydrogel electrode wrapped with a bimetallic organic framework derivative, wherein the hydrogel electrode wrapped with a bimetallic organic framework derivative is used to degrade the antibiotic wastewater, wherein the hydrogel electrode wrapped with a bimetallic organic framework derivative is based on a hydrogel, and a cobalt-iron bimetallic organic framework derivative is loaded on the hydrogel base, and the cobalt-iron bimetallic organic framework derivative includes CoFe 2 O4 and Co 3 Fe 7 The bimetallic organic framework derivative-wrapped hydrogel electrode used in the present invention, on the one hand, can provide attachment sites for the bimetallic organic framework derivatives and protect the bimetallic organic framework derivatives from falling off the electrode due to the three-dimensional network structure of the hydrogel. At the same time, due to the characteristics of the hydrogel such as rough surface and rich pore structure, the electron transfer efficiency and mass transfer rate of the electrode can be significantly improved through the multiple transfer effect of electrons, so that the substances in the electro-Fenton reaction system are fully in contact with the bimetallic organic framework derivatives, thereby accelerating the reaction rate. On the other hand, the cobalt-iron bimetallic organic framework derivatives include CoFe 2 O 4 and Co 3 Fe 7 The iron and cobalt in the catalyst can efficiently and quickly activate the hydrogen peroxide generated by cathode reduction into hydroxyl radicals (·OH) and superoxide radicals (·O 2 - ) and singlet oxygen ( 1 O 2 ), and at the same time it is oxidized to generate some high-valent metal oxygen species. These active substances participate in the degradation of antibiotics together, thereby promoting the electro-Fenton reaction and increasing the reaction rate. In addition, Co 3 Fe 7 The electron transfer between the catalyst and the external substance can be accelerated, and the reaction rate of the catalyst can be further improved. The method of the present invention has the advantages of good degradation effect, high treatment efficiency, good stability, good recyclability, low metal leaching concentration, strong anti-interference ability, etc., and can maintain high catalytic activity in a wide range of current density, pH value and antibiotic concentration, and maintain high adaptability in different water environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 These are scanning electron microscopy images and transmission electron microscopy images of the hydrogel electrode wrapped with a bimetallic organic framework derivative in Example 1 of the present invention.

[0021] Figure 2 The bimetallic organic framework derivative (CoFe 2 O 4 / Co 3 Fe 7 ), X-ray diffraction patterns of MIL-88B(Fe), Co-MIL-88B(Fe), and CMIL-88B(Fe).

[0022] Figure 3 The bimetallic organic framework derivative (CoFe 2 O 4 / Co3 Fe 7 ), X-ray photoelectron scanning full spectrum of MIL-88B(Fe), Co-MIL-88B(Fe), and CMIL-88B(Fe).

[0023] Figure 4 The bimetallic organic framework derivative (CoFe 2 O 4 / Co 3 Fe 7 ), Fe spectrum and Co spectrum in the X-ray photoelectron spectrum of MIL-88B(Fe), Co-MIL-88B(Fe), and CMIL-88B(Fe).

[0024] Figure 5 The bimetallic organic framework derivative hydrogel electrode (CoFe 2 O 4 / Co 3 Fe 7 @CH) Graph showing changes in metal leaching during the electro-Fenton reaction.

[0025] Figure 6 The bimetallic organic framework derivative hydrogel electrode (CoFe 2 O 4 / Co 3 Fe 7 @CH) shows the degradation effect of tetracycline under different current density conditions.

[0026] Figure 7 The bimetallic organic framework derivative hydrogel electrode (CoFe 2 O 4 / Co 3 Fe 7 @CH) shows the degradation effect of tetracycline under different pH conditions.

[0027] Figure 8 The bimetallic organic framework derivative hydrogel electrode (CoFe 2 O 4 / Co 3 Fe 7 @CH) treatment of tetracycline wastewater with different concentrations.

[0028] Fig. 9 The bimetallic organic framework derivative hydrogel electrode (CoFe 2 O 4 / Co 3 Fe 7@CH) shows the degradation effect of tetracycline under the coexistence of different anions.

[0029] Fig.10 The bimetallic organic framework derivative hydrogel electrode (CoFe 2 O 4 / Co 3 Fe 7 @CH) shows the degradation effect of tetracycline under different water quality conditions. DETAILED DESCRIPTION

[0030] The present invention is further described below in conjunction with the accompanying drawings and specific preferred embodiments, but the protection scope of the present invention is not limited thereby. The materials and instruments used in the following embodiments are all commercially available.

[0031] Example 1

[0032] A method for treating antibiotic wastewater using a hydrogel electrode wrapped with a bimetallic organic framework derivative of the present invention, specifically using a hydrogel electrode wrapped with a bimetallic organic framework derivative to degrade tetracycline wastewater, comprises the following steps:

[0033] The bimetallic organic framework derivative hydrogel electrode (CoFe 2 O 4 / Co 3 Fe 7 @CH) as the cathode and platinum as the anode, add 100 mL, pH value is 4.8, initial concentration is 20 mg·L -1 tetracycline wastewater, and then add sodium sulfate to make the concentration of sodium sulfate in the system 0.05 mol·L -1 The current was set to 45 mA (corresponding to a current density of 5 mA cm -2 ), and the electro-Fenton reaction was carried out for 60 minutes to achieve the treatment of tetracycline wastewater.

[0034] Control group 1: CH was used as the cathode, and other conditions were the same.

[0035] Control group 2: MIL-88B(Fe)@CH was used as the cathode, and other conditions were the same.

[0036] Control group 3: Co-MIL-88B(Fe)@CH was used as the cathode, and other conditions were the same.

[0037] Control group 4: CMIL-88B(Fe)@CH was used as the cathode, and other conditions were the same.

[0038] In the electro-Fenton reaction, 1 mL of sample was taken at regular intervals (0 min, 15 min, 30 min, 45 min, 60 min) and filtered through a 0.22 μm filter membrane. The peak area change of tetracycline at different degradation times was then measured by high performance liquid chromatography to determine the concentration of tetracycline after degradation, thereby obtaining the degradation effect of different hydrogel electrodes on tetracycline.

[0039] In this embodiment, the bimetallic organic framework derivative hydrogel electrode (CoFe 2 O 4 / Co 3 Fe 7 @CH) preparation method, comprising the following steps:

[0040] (1) 6.7 mmol ferric chloride (1.8 g), 3.3 mmol cobalt dichloride (0.4 g) and 10 mmol terephthalic acid (1.6 g) were added to 60 mL N, N-dimethylformamide, stirred evenly, and placed in a microwave hydrothermal reactor. The power of the microwave hydrothermal reactor was set to 1000 W, and the microwave hydrothermal reaction was carried out at 150 ° C for 40 min. After the reaction was completed, N, N-dimethylformamide and methanol were used for repeated washing, 3 times each, and dried in a vacuum oven at 60 ° C for 12 h to obtain Co-MIL-88B (Fe).

[0041] (2) In a nitrogen atmosphere, the Co-MIL-88B(Fe) obtained in step (1) was heated at 5°C min -1 The temperature was raised to 600 °C and calcined for 2 h to obtain a bimetallic organic framework derivative named CoFe 2 O 4 / Co 3 Fe 7 .

[0042] (3) 40 mg of the bimetallic organic framework derivative obtained in step (2) was added to 32 mL of a mixed aqueous solution containing nanocellulose and agar, wherein the mixed aqueous solution contained 20 g of nanocellulose and 0.6 g of agar powder, and the mixture was stirred evenly. The mixture was placed in an oven and evaporated at 60° C. for 3 h. After the solvent evaporated, 4 mL of sulfuric acid solution (the concentration of the solution was 1 mol·L -1 ), 4 mL N, N'-methylenebisacrylamide solution (the mass fraction of the solution is 4%) as a cross-linking agent, and the cross-linking reaction was carried out for 3 minutes. The reaction product was cut into a rectangle with an area of ​​3 cm × 3 cm with a knife to obtain a hydrogel electrode wrapped with a bimetallic organic framework derivative, named CoFe 2 O 4 / Co 3 Fe 7 @CH.

[0043] In the control group 1, the preparation method of CH was adopted, comprising the following steps:

[0044] Take 32 mL of a mixed aqueous solution containing nanocellulose and agar, wherein the nanocellulose is 20 g and the agar powder is 0.6 g, put it into an oven and evaporate it at 60 ° C for 3 h. After the solvent evaporates, add 4 mL of sulfuric acid solution (the concentration of the solution is 1 mol·L -1 ), 4 mL of N,N'-methylenebisacrylamide solution (the mass fraction of the solution is 4%) as a cross-linking agent, and the cross-linking reaction is carried out for 3 minutes. The reaction product is cut into a rectangle with an area of ​​3 cm × 3 cm with a knife to obtain CH.

[0045] In control group 2, the preparation method of MIL-88B(Fe)@CH was adopted, comprising the following steps:

[0046] (1) 6.7 mmol ferric chloride (1.8 g) and 10 mmol terephthalic acid (1.6 g) were added to 60 mL N,N-dimethylformamide, stirred evenly, and placed in a microwave hydrothermal reactor. The power of the microwave hydrothermal reactor was set to 1000 W, and the microwave hydrothermal reaction was carried out at 150°C for 40 min. After the reaction was completed, N,N-dimethylformamide and methanol were used for repeated washing, 3 times each, and dried in a vacuum oven at 60°C for 12 h to obtain MIL-88B(Fe).

[0047] (2) 40 mg of MIL-88B (Fe) obtained in step (1) was added to 32 mL of a mixed aqueous solution containing nanocellulose and agar, wherein the nanocellulose was 20 g and the agar powder was 0.6 g. The mixture was stirred evenly and placed in an oven for evaporation at 60° C. for 3 h. After the solvent was evaporated, 4 mL of sulfuric acid solution (the concentration of the solution was 1 mol·L -1 ), 4 mL of N,N'-methylenebisacrylamide solution (the mass fraction of the solution is 4%) was used as a cross-linking agent, and the cross-linking reaction was carried out for 3 minutes. The reaction product was cut into a rectangle with an area of ​​3 cm × 3 cm with a knife to obtain MIL-88B(Fe)@CH.

[0048] In control group 3, Co-MIL-88B(Fe)@CH was used, which was prepared by the same method as the hydrogel electrode (CoFe 2 O 4 / Co 3 Fe 7 The preparation method of the present invention is basically the same as that of the present invention, except that in step (2), no calcination is performed.

[0049] In control group 4, the preparation method of CMIL-88B(Fe)@CH was adopted, comprising the following steps:

[0050] (1) 6.7 mmol ferric chloride (1.8 g) and 10 mmol terephthalic acid (1.6 g) were added to 60 mL N,N-dimethylformamide, stirred evenly, and placed in a microwave hydrothermal reactor. The power of the microwave hydrothermal reactor was set to 1000 W, and the microwave hydrothermal reaction was carried out at 150°C for 40 min. After the reaction was completed, N,N-dimethylformamide and methanol were used for repeated washing, 3 times each, and dried in a vacuum oven at 60°C for 12 h to obtain MIL-88B(Fe).

[0051] (2) In a nitrogen atmosphere, the MIL-88B(Fe) obtained in step (1) was heated at 5°C min -1 The temperature was raised to 600°C and calcined for 2 h to obtain CMIL-88B(Fe).

[0052] (3) 40 mg of CMIL-88B (Fe) obtained in step (2) was added to 32 mL of a mixed aqueous solution containing nanocellulose and agar, wherein the nanocellulose was 20 g and the agar powder was 0.6 g, and the mixture was stirred evenly. The mixture was placed in an oven and evaporated at 60° C. for 3 h. After the solvent evaporated, 4 mL of sulfuric acid solution (the concentration of the solution was 1 mol·L -1 ), 4 mL of N,N'-methylenebisacrylamide solution (the mass fraction of the solution is 4%) was used as a cross-linking agent, and the cross-linking reaction was carried out for 3 min. The reaction product was cut into a rectangle with an area of ​​3 cm × 3 cm with a knife to obtain CMIL-88B(Fe)@CH.

[0053] Figure 1 These are scanning electron microscopy images and transmission electron microscopy images of the hydrogel electrode wrapped with a bimetallic organic framework derivative in Example 1 of the present invention. Figure 1 In the figure, (a) to (c) are the surface morphologies of the electrode at different magnifications, (d) is the cross-sectional morphology of the electrode, (e) and (f) are the crystal structures of the bimetallic organic framework derivatives in the electrode, and (g) and (h) are the lattice fringe spacings of the bimetallic organic framework derivatives in the electrode. Figure 1 It can be observed that the bimetallic organic framework derivative is uniformly wrapped in the hydrogel ((a)~(d)), which indicates that the bimetallic organic framework derivative is well combined with the hydrogel as a whole; at the same time, the surface of the hydrogel electrode wrapped with the bimetallic organic framework derivative is porous and rough, with a three-dimensional skeleton structure, which is conducive to material exchange and gas adsorption. In addition, from Figure 1It can be seen that there are two different substances ((e), (f)) with obvious lattice stripe array structures ((g), (h)), corresponding to CoFe 2 O 4 and Co 3 Fe 7 , indicating that the catalyst in the hydrogel electrode encapsulated with a bimetallic organic framework derivative is composed of these two substances.

[0054] Figure 2 The bimetallic organic framework derivative (CoFe 2 O 4 / Co 3 Fe 7 ), MIL-88B(Fe), Co-MIL-88B(Fe), CMIL-88B(Fe). Figure 2 It can be seen that after calcination, CMIL-88B(Fe) and CoFe 2 O 4 / Co 3 Fe 7 The main peak position of CMIL-88B(Fe) and CoFe 2 O 4 / Co 3 Fe 7 The main peak position of is also different, indicating that cobalt doping causes a change in the crystal growth direction. 2 O 4 / Co 3 Fe 7 ) was compared with the X-ray diffraction pattern of the standard substance, and it was determined that the prepared bimetallic organic framework derivative was CoFe 2 O 4 and Co 3 Fe 7 .

[0055] Figure 3 The bimetallic organic framework derivative (CoFe 2 O 4 / Co 3 Fe 7 ), X-ray photoelectron scanning full spectrum of MIL-88B(Fe), Co-MIL-88B(Fe), and CMIL-88B(Fe). Figure 4 The bimetallic organic framework derivative (CoFe 2 O 4 / Co 3 Fe7 ), Fe spectrum and Co spectrum in X-ray photoelectron spectra of MIL-88B(Fe), Co-MIL-88B(Fe), and CMIL-88B(Fe). Figure 3 It can be seen that the bimetallic organic framework derivative (CoFe 2 O 4 / Co 3 Fe 7 ) is composed of C, O, Fe, and Co elements. Figure 4 (a) It can be seen that CMIL-88B (Fe) and bimetallic organic framework derivatives (CoFe 2 O 4 / Co 3 Fe 7 )Fe 3+ The peak of Fe 2+ The peak of the cobalt-doped bimetallic organic framework derivative (CoFe 2 O 4 / Co 3 Fe 7 )Fe 0 , indicating that cobalt doping can promote Fe 0 Generation of. Figure 4 (b) It can be seen that the bimetallic organic framework derivative (CoFe 2 O 4 / Co 3 Fe 7 ) 3+ The peak of Co almost disappeared. 2+ The peak of Co 0 It can be seen that after calcination, a large amount of high-valent metals (Fe 3+ 、Co 3+ ) is reduced to a low-valent metal (Fe 2+ 、Co 2+ , Fe 0 、Co 0 ), catalyst bimetallic organic framework derivative (CoFe 2 O 4 / Co 3 Fe 7 )The rich valence state of the metal inside increases the electron transfer rate inside the catalyst, thereby improving the catalytic activity of the catalyst.

[0056] Table 1 Catalytic effect of different hydrogel electrodes on tetracycline wastewater

[0057] Hydrogel Electrode Tetracycline removal rate (%) <![CDATA[Tetracycline removal rate (min -1 )]]> CH 47.7 0.01126 MIL-88B(Fe)@CH 58.8 0.01478 Co-MIL-88B(Fe)@CH 66.1 0.01747 CMIL-88B(Fe)@CH 57.9 0.01386 <![CDATA[CoFe 2 ABOUT 4 / What 3 Fe 7 @CH]]> 91.1 0.03700

[0058] As shown in Table 1, compared with other hydrogel electrodes (CH, MIL-88B(Fe)@CH, Co-MIL-88B(Fe)@CH and CMIL-88B(Fe)@CH), the bimetallic organic framework derivative hydrogel electrode (CoFe 2 O 4 / Co 3 Fe 7 @CH) can not only effectively remove tetracycline from wastewater, but also has a higher removal rate.

[0059] Table 2 Comparison of catalytic performance of existing electrodes

[0060]

[0061] It can be seen from Table 2 that compared with the existing electrodes, the bimetallic organic framework derivative hydrogel electrode (CoFe 2 O 4 / Co 3 Fe 7 @CH) can degrade tetracycline more quickly and efficiently.

[0062] In this example, the encapsulated bimetallic organic framework derivative hydrogel electrode (CoFe 2 O 4 / Co 3 Fe 7 @CH) metal leaching, such as Figure 5 As shown. Figure 5 It can be seen that in the electro-Fenton system constructed by encapsulating the bimetallic organic framework derivative hydrogel electrode, the final leaching concentrations of Fe and Co were 2.886 mg·L -1 , 0.381mg·L -1 , in line with relevant national standards (Fe<5mg·L -1 ,GB 3838-2002;Co<1mg·L -1 , GB 25467-2010).

[0063] The above results show that compared with the existing electrodes and other hydrogel electrodes (CH, MIL-88B(Fe)@CH, Co-MIL-88B(Fe)@CH and CMIL-88B(Fe)@CH), the bimetallic organic framework derivative hydrogel electrode (CoFe 2 O 4 / Co 3 Fe 7 @CH) has the following advantages: more stable composition, rich internal valence states of the catalyst, higher catalytic activity, and thus better catalytic degradation effect.

[0064] Example 2

[0065] A method for treating antibiotic wastewater using a hydrogel electrode wrapped with a bimetallic organic framework derivative of the present invention, specifically a method for treating tetracycline wastewater using a hydrogel electrode wrapped with a bimetallic organic framework derivative under different current density conditions, comprising the following steps:

[0066] The bimetallic organic framework derivative hydrogel electrode (CoFe 2 O 4 / Co 3 Fe 7 @CH) as the cathode and platinum sheet as the anode, and 4 portions of 100 mL, pH 4.8, and initial concentration 20 mg·L were added. -1 tetracycline wastewater, and then add sodium sulfate to make the concentration of sodium sulfate in the system 0.05 mol·L -1 The electro-Fenton reaction was carried out for 60 min, with the currents set to 27 mA, 45 mA, 63 mA, and 90 mA (corresponding to current densities of 3 mA cm -2 , 5mA·cm -2 , 7mA·cm -2 、10mA·cm -2 ), to achieve the treatment of tetracycline wastewater. The sampling method is the same as that in Example 1.

[0067] Figure 6 The bimetallic organic framework derivative hydrogel electrode (CoFe 2 O 4 / Co 3 Fe 7 @CH) shows the degradation effect of tetracycline under different current density conditions. Figure 6 It can be seen that when the current density is 3 mA cm -2 , 5mA·cm -2 , 7mA·cm -2 、10mA·cm -2 When the current density is 5 mA·cm, the removal rate of tetracycline in the electro-Fenton system constructed by the hydrogel electrode wrapped with the bimetallic organic framework derivative is 85.4%, 91.1%, 88.5% and 85.2% respectively. It can be seen that the electro-Fenton system constructed by the present invention has a good removal effect on tetracycline wastewater in a wide current range. -2 This is because: if the current is too large or too small, other side reactions will occur and dominate, resulting in a decrease in the removal efficiency of tetracycline.

[0068] Example 3

[0069] A method for treating antibiotic wastewater using a hydrogel electrode wrapped with a bimetallic organic framework derivative of the present invention, specifically a method for treating tetracycline wastewater using a hydrogel electrode wrapped with a bimetallic organic framework derivative under different pH conditions, comprising the following steps:

[0070] The bimetallic organic framework derivative hydrogel electrode (CoFe 2 O 4 / Co 3 Fe 7 @CH) as the cathode and platinum sheet as the anode, and 4 portions of 100 mL with an initial concentration of 20 mg·L were added respectively. -1 The pH values ​​of tetracycline wastewater were adjusted to 3, 4.8, 7, and 9, respectively, and sodium sulfate was added to make the concentration of sodium sulfate in the system 0.05 mol·L -1 The electro-Fenton reaction was carried out for 60 min, with the current set to 45 mA (corresponding to a current density of 5 mA cm -2 ), to achieve the treatment of tetracycline wastewater. The sampling method is the same as that in Example 1.

[0071] Figure 7 The bimetallic organic framework derivative hydrogel electrode (CoFe 2 O 4 / Co 3 Fe 7 @CH) shows the degradation effect of tetracycline under different pH conditions. Figure 7 It can be seen that when the pH is 3, 4.8, 7, and 9, the removal rates of tetracycline by the electro-Fenton system constructed by the hydrogel electrode wrapped with a bimetallic organic framework derivative are 86.7%, 91.1%, 85.5%, and 86.4%, respectively. It can be seen that the electro-Fenton system constructed by the present invention has a good removal effect on tetracycline wastewater in a wide pH range. When the pH is the initial value of 4.8, the electro-Fenton system has the best removal effect, which proves that the electro-Fenton system constructed by the present invention does not need to further adjust the pH value and is easy to operate.

[0072] Example 4

[0073] A method for treating antibiotic wastewater using a hydrogel electrode wrapped with a bimetallic organic framework derivative of the present invention, specifically a method for treating tetracycline wastewater with different initial concentrations using a hydrogel electrode wrapped with a bimetallic organic framework derivative, comprises the following steps:

[0074] The bimetallic organic framework derivative hydrogel electrode (CoFe 2 O 4 / Co 3 Fe 7@CH) as the cathode and platinum sheet as the anode, and three portions of 100 mL of tetracycline wastewater with a pH value of 4.8 were added. The concentration of the tetracycline wastewater was 10 mg·L -1 , 20mg·L -1 、30mg·L -1 , then add sodium sulfate to make the concentration of sodium sulfate in the system 0.05 mol·L -1 The electro-Fenton reaction was carried out for 60 min, with the current set to 45 mA (corresponding to a current density of 5 mA cm -2 ), to achieve the treatment of tetracycline wastewater. The sampling method is the same as that in Example 1.

[0075] Figure 8 The bimetallic organic framework derivative hydrogel electrode (CoFe 2 O 4 / Co 3 Fe 7 @CH) treatment of different concentrations of tetracycline wastewater degradation effect diagram. Figure 8 It can be seen that when the concentration of tetracycline in wastewater is 10 mg·L -1 , 20mg·L -1 、30mg·L -1 When the electro-Fenton system constructed by wrapping the bimetallic organic framework derivative hydrogel electrode has a tetracycline removal rate of 87.8%, 91.1% and 84.1% respectively. It can be seen that in the electro-Fenton system constructed by the present invention, the initial concentration of tetracycline in the wastewater is 10 mg·L -1 ~30mg·L -1 It has a good removal effect.

[0076] Example 5

[0077] A method for treating antibiotic wastewater using a hydrogel electrode wrapped with a bimetallic organic framework derivative of the present invention, specifically a method for treating tetracycline wastewater using a hydrogel electrode wrapped with a bimetallic organic framework derivative under the coexistence of different anions, comprises the following steps:

[0078] The bimetallic organic framework derivative hydrogel electrode (CoFe 2 O 4 / Co 3 Fe 7 @CH) as the cathode and platinum sheet as the anode, and 9 portions of 100 mL, pH 4.8, and initial concentration of 20 mg·L were added. -1The tetracycline wastewater contains different concentrations of chloride ions, carbonate ions, and phosphate ions (i.e., sodium chloride, sodium carbonate, and sodium phosphate are added to the tetracycline wastewater), and then sodium sulfate is added to make the total concentration of sodium salt in the system 0.05 mol·L -1 The electro-Fenton reaction was carried out for 60 min, with the current set to 45 mA (corresponding to a current density of 5 mA cm -2 ), to achieve the treatment of tetracycline wastewater. The sampling method is the same as that in Example 1.

[0079] Fig. 9 The bimetallic organic framework derivative hydrogel electrode (CoFe 2 O 4 / Co 3 Fe 7 @CH) shows the degradation effect of tetracycline under different anion coexistence conditions. Fig. 9 As shown in the figure, when chloride ions are present in the wastewater, no matter how high the chloride ion concentration is, the electro-Fenton system constructed by the hydrogel electrode wrapped with a bimetallic organic framework derivative will accelerate the degradation of tetracycline. This is because the system will convert chloride ions into chloride free radicals, which will also promote the degradation of tetracycline. When carbonate ions are present in the wastewater, carbonate ions can also accelerate the degradation of tetracycline like chloride ions at a lower concentration. This is because: carbonate ions can form a complex with metal ions in the reaction system, and the complex can promote H 2 O 2 Hydroxyl radicals are generated, which further promote the degradation of tetracycline; however, when the carbonate ion concentration increases from 10mmol·L -1 Increase to 20mmol·L -1 When the concentration of carbonate ions increases, the removal rate of tetracycline by the electro-Fenton system decreases. This is because: there is competition among various free radicals, and this competition is affected by the increase in carbonate ion concentration, which ultimately leads to a decrease in the removal rate of tetracycline. When phosphate ions are present in the wastewater, the removal rate of tetracycline by the electro-Fenton system shows a downward trend regardless of the phosphate concentration. This is because the presence of phosphates will produce less active free radicals, thereby reducing the generation of more active free radicals such as hydroxyl radicals, which ultimately leads to a lower removal rate of tetracycline.

[0080] Example 6

[0081] A method for treating antibiotic wastewater using a hydrogel electrode wrapped with a bimetallic organic framework derivative of the present invention, specifically a method for treating tetracycline wastewater using a hydrogel electrode wrapped with a bimetallic organic framework derivative under different water quality conditions, comprising the following steps:

[0082] The bimetallic organic framework derivative hydrogel electrode (CoFe2 O 4 / Co 3 Fe 7 @CH) as the cathode and platinum sheet as the anode, tap water containing tetracycline, river water (Xiangjiang River water), sludge supernatant, and medical wastewater were added respectively. The volume of the above wastewater was 100 mL, the pH value was 4.8, and the initial concentration was 20 mg·L -1 , then add sodium sulfate to make the concentration of sodium sulfate in the system 0.05 mol·L -1 The electro-Fenton reaction was carried out for 60 min, with the current set to 45 mA (corresponding to a current density of 5 mA cm -2 ), to achieve the treatment of tetracycline wastewater. The sampling method is the same as that in Example 1.

[0083] Fig.10 The bimetallic organic framework derivative hydrogel electrode (CoFe 2 O 4 / Co 3 Fe 7 @CH) shows the degradation effect of tetracycline under different water quality conditions. Fig.10 As shown in the figure, in these four actual water bodies, the removal rate of tetracycline by the electro-Fenton system constructed by encapsulating the bimetallic organic framework derivative hydrogel electrode was maintained above 85%, indicating that the electro-Fenton catalytic system has great application potential in actual water bodies. 2 O 4 / Co 3 Fe 7 @CH can still maintain good stability and catalytic activity in complex water bodies.

[0084] Based on the above results, it can be seen that compared with conventional electrodes, the bimetallic organic framework derivative hydrogel electrode used in the present invention has the advantages of developed pore structure, rough surface, not easy to fall off from the electrode, and no secondary pollution. The electro-Fenton system constructed in this way has the advantages of fast electron transfer rate, high mass transfer efficiency, multiple types of active substances, strong anti-interference ability, strong adaptability, etc., and can be used in a wide current density (3-10 mA cm -2 ), pH (3-9) and initial tetracycline concentration (10-30 mg·L -1) range to efficiently remove antibiotics from wastewater. Taking tetracycline as an example, in four water matrices including tap water, river water, sludge supernatant and medical wastewater, the removal rate of tetracycline by the electro-Fenton system constructed by the present invention can reach more than 85%. The method of treating antibiotic wastewater by using hydrogel electrodes wrapped with bimetallic organic framework derivatives of the present invention has the advantages of good degradation effect, high treatment efficiency, good stability, good recyclability, low metal leaching concentration, strong anti-interference ability, etc. It is an electro-Fenton method that can be widely used and has high use value and application prospects.

[0085] The above is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as above in the preferred embodiment, it is not used to limit the present invention. Any technician familiar with the art can make many possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Therefore, any simple modification, equivalent replacement, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention, still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for treating antibiotic wastewater using a hydrogel electrode wrapped with a bimetallic organic framework derivative, characterized in that: The method utilizes a hydrogel electrode wrapped with a bimetallic organic framework derivative to degrade antibiotic wastewater; the hydrogel electrode wrapped with a bimetallic organic framework derivative is based on a hydrogel, and the hydrogel base is loaded with a cobalt-iron bimetallic organic framework derivative, and the cobalt-iron bimetallic organic framework derivative includes CoFe2O4 and Co3Fe7.

2. The method for treating antibiotic wastewater using a hydrogel electrode wrapped with a bimetallic organic framework derivative according to claim 1, characterized in that: The preparation method of the bimetallic organic framework derivative hydrogel electrode comprises the following steps: S1, mixing iron salt, cobalt salt, organic ligand and organic solvent, and subjecting to microwave hydrothermal reaction to obtain Co-MIL-88B(Fe); S2, calcining the Co-MIL-88B(Fe) obtained in step S1 to obtain a bimetallic organic framework derivative; S3, mixing the bimetallic organic framework derivative obtained in step S2 with a mixed aqueous solution containing cellulose and agar, evaporating, adding a crosslinking agent, and performing a crosslinking reaction to obtain a hydrogel electrode wrapped with the bimetallic organic framework derivative.

3. The method for treating antibiotic wastewater using a hydrogel electrode wrapped with a bimetallic organic framework derivative according to claim 2, characterized in that: In step S3, the mass volume ratio of the bimetallic organic framework derivative to the mixed aqueous solution containing cellulose and agar is 40 mg~50 mg: 30 mL~32 mL, the mass ratio of the bimetallic organic framework derivative to the cellulose in the mixed aqueous solution containing cellulose and agar is 0.04~0.05: 19.9~20.1, and the mass ratio of the bimetallic organic framework derivative to the agar in the mixed aqueous solution containing cellulose and agar is 0.4~0.5: 6~7.

4. The method for treating antibiotic wastewater using a hydrogel electrode wrapped with a bimetallic organic framework derivative according to claim 3, characterized in that: In step S3, the cellulose in the mixed aqueous solution containing cellulose and agar is nanocellulose, the crosslinking agent is a sulfuric acid solution and an N,N'-methylenebisacrylamide solution, the mass volume ratio of the bimetallic organic framework derivative, the sulfuric acid solution, and the N,N'-methylenebisacrylamide solution is 40 mg to 50 mg: 4 mL to 5 mL: 4 mL to 5 mL, and the concentration of the sulfuric acid solution is 1 mol·L -1 The mass fraction of the N,N'-methylenebisacrylamide solution is 4%; the evaporation temperature is 60°C to 80°C; the evaporation time is 2h to 4h; and the cross-linking reaction time is 2min to 3min.

5. The method for treating antibiotic wastewater using a hydrogel electrode wrapped with a bimetallic organic framework derivative according to claim 4, characterized in that: In step S1, the mass ratio of the iron salt, the cobalt salt and the organic ligand is 1.8-1.9: 0.3-0.4: 1.6-1.7, and the mass volume ratio of the iron salt to the organic solvent is 1.8g-1.9g: 55mL-60mL.

6. The method for treating antibiotic wastewater using a hydrogel electrode wrapped with a bimetallic organic framework derivative according to claim 5, characterized in that: In step S1, the iron salt is ferric chloride, the cobalt salt is cobalt dichloride, the organic ligand is terephthalic acid, and the organic solvent is N,N-dimethylformamide; the temperature of the microwave hydrothermal reaction is 150°C, the time of the microwave hydrothermal reaction is 40 minutes, the equipment used for the microwave hydrothermal reaction is a microwave hydrothermal synthesizer, and the power of the microwave hydrothermal synthesizer is 1000W; after the microwave hydrothermal reaction, the following treatment is also included: the microwave hydrothermal reaction product is washed with N,N-dimethylformamide and methanol in sequence, and vacuum dried at a temperature of 60°C to 80°C for 8h to 12h.

7. The method for treating antibiotic wastewater using a hydrogel electrode wrapped with a bimetallic organic framework derivative according to claim 6, characterized in that: In step S2, the calcination is carried out in a nitrogen atmosphere, and the heating rate during the calcination is 4°C·min -1 ~6℃·min -1 The calcination temperature is 580°C to 620°C, and the calcination time is 2h to 3h.

8. The method for treating antibiotic wastewater using a hydrogel electrode wrapped with a bimetallic organic framework derivative according to any one of claims 1 to 7, characterized in that: The degradation treatment is as follows: using a hydrogel electrode wrapped with a bimetallic organic framework derivative as a cathode, using a platinum sheet as an anode, adding antibiotic wastewater, and performing an electro-Fenton reaction to achieve degradation of the antibiotics in the wastewater.

9. The method for treating antibiotic wastewater using a hydrogel electrode wrapped with a bimetallic organic framework derivative according to claim 8, characterized in that: The initial concentration of antibiotics in the antibiotic wastewater is 10 mg·L -1 ~30mg·L -1 The antibiotic in the antibiotic wastewater is tetracycline, and the pH value of the antibiotic wastewater is 3-9.

10. The method for treating antibiotic wastewater using a hydrogel electrode wrapped with a bimetallic organic framework derivative according to claim 9, characterized in that: The current density during the electro-Fenton reaction was 3 mA cm -2 ~10mA·cm -2 The electro-Fenton reaction time is ≥ 60 min; the electro-Fenton reaction process also includes adding electrolytes to the antibiotic wastewater to make the concentration of electrolytes in the reaction system 0.05 mol·L -1 , the electrolyte is sodium sulfate.

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