Anode catalyst-metal organic framework material capable of rapidly electrolyzing saline water to synthesize chlorine and disinfectant as well as preparation method and application of anode catalyst-metal organic framework material

Abstract

The invention discloses a metal-organic framework material capable of being used for efficiently electrolyzing saline water to produce chlorine and a disinfectant as well as a preparation method and application of the metal-organic framework material. According to the method, an environmental metal-organic framework material is constructed by taking 3, 3 ', 5, 5'-biphenyltetracarboxylic acid as an organic ligand and nickel chloride and ferrous chloride as metal centers. Under the applied voltage, the material can adsorb chloride ions in a 4M NaCl saline solution with the pH value of 1 and oxidize the chloride ions into chlorine, the produced chlorine and water are subjected to a disproportionation reaction to generate hypochlorous acid (active chlorine), efficient sterilization can be achieved, the rate of generating the active chlorine at 10 mAcm <-2 > is 1.24 mg L <-1 > min <-1 > and is higher than that of precious metal RuO2 (0.90 mg L <-1 > min <-1 >), and the material can be applied to direct seawater electrolysis. According to the method, efficient chlorine and disinfectant production can be achieved, seawater electrolysis can be directly developed, the efficient disinfectant is prepared, and the application prospect is wide.

Description

Technical Field

[0001] The present invention belongs to the field of environment, and specifically relates to an anode catalyst capable of rapidly electrolyzing salt water to synthesize chlorine and disinfectant, namely a metal organic framework material, and a preparation method and application thereof. Background Art

[0002] With the increasing attention paid to clean energy and environmental protection around the world, the technical research on the efficient electrolysis of brine and seawater to produce chlorine and disinfectants has become a hot topic in current scientific research. Chlorine and disinfectants play a vital role in public health, industrial disinfection, drinking water treatment and other fields. Traditional methods for producing chlorine and disinfectants mainly rely on the electrolysis of brine. However, traditional coated titanium as an anode consumes a lot of energy during the electrolysis process. Therefore, the development of an anode catalyst for efficient electrolysis of brine is of great significance for the synthesis of chlorine and disinfectants.

[0003] The Chinese patent application document with publication number CN116905015A discloses a dual-functional metal organic framework nanomaterial and its preparation method and use. The material is NiRhMnMOF / NF nanomaterial, which is composed of a metal organic framework material and nickel foam, and the metal organic framework material is loaded on the nickel foam; the metal organic framework material is a nanomaterial with a two-dimensional array nanosheet structure formed by nickel, rhodium and manganese as metal nodes or clusters and terephthalic acid as an organic framework. The preparation method is: nickel salt, rhodium salt, manganese salt and terephthalic acid are added to a mixed solvent in sequence to obtain a mixed dispersion; the pretreated nickel foam is placed in a reactor, and the mixed dispersion is poured into the reactor for hydrothermal reaction; the nickel foam after the reaction is washed with alcohol, washed with water and vacuum dried in sequence. The material can be used as a dual-functional electrocatalyst for HER and UOR, with a voltage of 1.34V (Vvs.RHE), and a 3h urea degradation rate of more than 99%. However, the performance of the metal organic framework material of the patent is poor, so it needs to be further improved. Summary of the invention

[0004] The technical problem to be solved by the present invention is how to solve the problem of low efficiency of electrolyzing brine in existing anode catalysts.

[0005] The present invention solves the above technical problems through the following technical means:

[0006] The first aspect of the present invention provides a method for preparing a NiFe-based metal-organic framework material, comprising the following steps: using 3,3',5,5'-biphenyltetracarboxylic acid as an organic ligand, N,N-dimethylformamide as an organic solvent, and nickel salt and iron salt as sources of metal centers, performing a solvothermal reaction to obtain a NiFe-based metal-organic framework material.

[0007] Preferably, the dosage ratio of the organic ligand, NiFe metal, and organic solvent is 0.1 - 0.5 mmol: 0.4 - 1.2 mmol: 8 - 15 mL, and more preferably 0.2 mmol: 0.8 mmol: 12 mL.

[0008] Preferably, the nickel salt is selected from any one of nickel acetate, nickel nitrate, nickel chloride, nickel sulfate, and nickel phosphate, and the iron salt is selected from any one of ferrous acetate, ferrous nitrate, ferrous chloride, ferrous sulfate, and ferrous phosphate.

[0009] Preferably, the molar ratio of the nickel salt to the iron salt is (0.5 - 2):(1 - 3).

[0010] Preferably, the temperature of the solvothermal reaction is 100 - 160 °C, and the time is 8 - 16 h. Further optimizing the temperature is 140 °C and the time is 14 h.

[0011] In the second aspect of the present invention, a NiFe-based metal-organic framework material prepared by the above preparation method is proposed.

[0012] In the third aspect of the present invention, the application of the above NiFe-based metal-organic framework material in the preparation of chlorine and disinfectant by electrolyzing brine is proposed.

[0013] Preferably, the NiFe-based metal-organic framework material is placed in a three-electrode electrolytic cell, a 4M NaCl brine solution with a pH of 1 - 3 is used as the electrolyte and a voltage is applied, and the generated chlorine gas is bubbled into pure water, and the logarithm of the removed bacteria is 4 - 7.

[0014] Preferably, when the brine is replaced with seawater, the logarithm of the removed bacteria in the reacted seawater solution is 3 - 7.

[0015] Preferably, the synthesized metal-based MOF is loaded on carbon cloth as the working electrode, a saturated calomel electrode is used as the reference electrode, and a carbon rod is used as the counter electrode to form a three-electrode system.

[0016] Preferably, the brine solution is prepared as follows: using hydrochloric acid, sulfuric acid or perchloric acid, adjust the pH value of the 4M NaCl solution to 1 - 3.

[0017] The beneficial effects of the present invention are as follows:

[0018] 1. The present invention uses 3,3',5,5'-biphenyltetracarboxylic acid as the organic ligand and nickel chloride and ferrous chloride as the metal centers to construct an environmental metal-organic framework material. Under the applied voltage, this material can adsorb chloride ions in a 4M NaCl brine solution with a pH of 1 - 3 and oxidize them into chlorine gas. The generated chlorine gas undergoes a disproportionation reaction with water to form hypochlorous acid (active chlorine), which can efficiently sterilize, and at 10 mA cm -2The rate of active chlorine generation is 1.24 mg L -1 min -1 , higher than that of noble metal RuO 2 (0.90 mg L -1 min -1 ). At 100 mA cm -2 , the overpotential is lower than that of noble metal materials (dimensionally stable anode DSA).

[0019] 2. This method can not only achieve efficient production of chlorine gas and disinfectants, but also directly develop seawater electrolysis to prepare highly efficient disinfectants, with broad application prospects. Brief Description of the Drawings

[0020] Figure 1 It is the scanning electron microscope image of the materials prepared in Examples 1 to 3 of the present invention;

[0021] Figure 2 It is the XRD spectra of the materials prepared in Examples 1 to 3 of the present invention and the standard MOF material;

[0022] Figure 3 It is the comparison chart of the performance test results of Examples 1 to 3, dimensionally stable anode (DSA), RuO 2 and the substrate carbon cloth;

[0023] In the figure, a to c respectively refer to Examples 1 to 3. Detailed Embodiments

[0024] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0025] The test materials and reagents used in the following embodiments can be obtained from commercial channels without special instructions.

[0026] For those not specifying specific techniques or conditions in the embodiments, they can all be carried out according to the techniques or conditions described in the literature in this field or according to the product specifications. Without special instructions, the quantitative tests in the following embodiments are all set with more than three repeated experiments, and the results are averaged.

[0027] Preparation of brine solution: Use perchloric acid to adjust the pH value of 4M NaCl solution to 1 - 3.

[0028] Example 1:

[0029] A preparation method of NiFe-based metal-organic framework material, comprising the following steps:

[0030] Using 3,3',5,5'-biphenyltetracarboxylic acid (0.2 mmol) as the organic ligand, N,N-dimethylformamide (12 mL) as the organic solvent, and nickel chloride and ferrous chloride (a total of 0.8 mmol) with a molar ratio of 0.5:1 as the metal center, performing a solvothermal reaction at 140 °C for 14 h to obtain the NiFe-based metal-organic framework material.

[0031] The successful preparation of the material was confirmed by scanning electron microscopy characterization and XRD spectra. The characterization diagrams and performance test results are shown in Figures 1-2 as follows.

[0032] Material application:

[0033] Placing the NiFe-based metal-organic framework material of this example in a three-electrode electrolytic cell (the synthesized metal-based MOF is loaded on carbon cloth as the working electrode, the saturated calomel electrode as the reference electrode, and the carbon rod as the counter electrode to form a three-electrode system), using 50 mL of 4M NaCl brine solution with a pH of 1 as the electrolyte and applying a voltage of 1.5 V vs. RHE for 1 min, bubbling the generated chlorine gas into 5 mL of pure water. The logarithmic value of Escherichia coli removed by this technology is 4.4;

[0034] When replaced with seawater (seawater only filters insoluble substances without further treatment), the logarithmic value of Escherichia coli removed by the seawater solution after reacting for 1 min with a voltage of 1.9 V vs. RHE is 3.7.

[0035] The overpotential of the prepared metal-organic framework material at 100 mA cm -2 is lower than that of noble metal materials (dimensionally stable anode DSA), as shown in Figure 3 We evaluate the performance by the overpotential to reach 100 mA cm -2 . The lower the overpotential, the better the performance. The rate of generating active chlorine of this material at 10 mA cm -2 is 1.24 mg L -1 min -1 , which is higher than that of noble metal RuO 2 (0.90 mg L -1 min -1 ).

[0036] Under the same conditions, without using the metal-organic framework material and only using carbon cloth to electrolyze brine to reach 10 mA cm -2It may require 2 V vs. RHE, while only 1.41 V vs. RHE is needed when using metal-organic framework materials. When electrolyzing brine with a large current, the electrical energy consumed by using pure carbon cloth is very large. Therefore, using this material can greatly save the consumption of electrical energy.

[0037] Example 2:

[0038] A preparation method of NiFe-based metal-organic framework material, comprising the following steps:

[0039] Using 3,3',5,5'-biphenyltetracarboxylic acid (0.1 mmol) as the organic ligand, N,N-dimethylformamide (8 mL) as the organic solvent, and nickel chloride and ferrous chloride (a total of 0.4 mmol) with a molar ratio of 1:1 as the metal center, carrying out a solvothermal reaction at 100 °C for 16 h to obtain the NiFe-based metal-organic framework material.

[0040] Material application:

[0041] Placing the NiFe-based metal-organic framework material of this example in a three-electrode electrolytic cell (the synthesized metal-based MOF is loaded on carbon cloth as the working electrode, the saturated calomel electrode as the reference electrode, and the carbon rod as the counter electrode to form a three-electrode system), using 50 mL of 4 M NaCl brine solution with a pH of 2 as the electrolyte and applying a voltage of 1.6 V vs. RHE for 2 min, bubbling the generated chlorine gas into 5 mL of pure water, and the logarithmic value of Escherichia coli removed by this technology is 6.7;

[0042] When replaced with seawater, the logarithmic value of Escherichia coli removed by the seawater solution after reacting at a voltage of 2.1 V vs. RHE for 2 min is 5.3.

[0043] Example 3:

[0044] A preparation method of NiFe-based metal-organic framework material, comprising the following steps:

[0045] Using 3,3',5,5'-biphenyltetracarboxylic acid (0.5 mmol) as the organic ligand, N,N-dimethylformamide (15 mL) as the organic solvent, and nickel chloride and ferrous chloride (a total of 1.2 mmol) with a molar ratio of 2:1 as the metal center, carrying out a solvothermal reaction at 160 °C for 8 h to obtain the NiFe-based metal-organic framework material.

[0046] Material application:

[0047] Place the NiFe-based metal-organic framework material of this embodiment in a three-electrode electrolytic cell (the synthesized metal-based MOF loaded on carbon cloth serves as the working electrode, the saturated calomel electrode serves as the reference electrode, and the carbon rod serves as the counter electrode to form a three-electrode system). Use 50 mL of 4M NaCl saline solution with a pH of 3 as the electrolyte and apply a voltage of 1.7 V vs. RHE for 3 min. Bubble the generated chlorine gas into 5 mL of pure water. The logarithmic value of Escherichia coli removed by this technology is 7.2;

[0048] When replaced with seawater, the logarithmic value of Escherichia coli removed by the seawater solution after reacting at a voltage of 2.3 V vs. RHE for 3 min is 6.9.

[0049] Summary of the bactericidal effects of Examples 1-3:

[0050] Taking Examples 1-3 as examples, the effects of the parameters of the NiFe-based metal-organic framework material (metal ratio, applied voltage, reaction duration) on the bactericidal effect against Escherichia coli are shown in the following table:

[0051] Table 1 Bactericidal effects of NiFe-based metal-organic framework materials against Escherichia coli under different parameters

[0052]

[0053] The above examples are only used to illustrate the technical solutions of the present invention, not to limit it; although the present invention has been described in detail with reference to the foregoing examples, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing examples, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for preparing a NiFe-based metal-organic framework material, characterized in that: The following steps are involved: Using 3,3',5,5'-biphenyltetracarboxylic acid as an organic ligand, N,N-dimethylformamide as an organic solvent, and nickel salt and iron salt as sources of metal centers, a solvothermal reaction was carried out to obtain a NiFe-based metal-organic framework material.

2. The preparation method according to claim 1, characterized in that: The usage ratio of the organic ligand, NiFe metal and organic solvent is 0.1-0.5 mmol: 0.4-1.2 mmol: 8-15 mL.

3. The preparation method according to claim 1, characterized in that: The nickel salt is selected from any one of nickel acetate, nickel nitrate, nickel chloride, nickel sulfate, and nickel phosphate, and the iron salt is selected from any one of ferrous acetate, ferrous nitrate, ferrous chloride, ferrous sulfate, and ferrous phosphate.

4. The preparation method according to claim 1, characterized in that: The molar ratio of the nickel salt to the iron salt is (0.5-2):(1-3).

5. The preparation method according to claim 1, characterized in that: The temperature of the solvent thermal reaction is 100-160° C. and the time is 8-16 hours.

6. A NiFe-based metal-organic framework material obtained by the preparation method according to any one of claims 1 to 5.

7. Use of the NiFe-based metal-organic framework material according to claim 6 in the electrolysis of brine to prepare chlorine and disinfectants.

8. The use according to claim 7, characterized in that: The 4M NaCl salt water solution with a pH of 1-3 is used as the electrolyte and a voltage is applied to bubble the generated chlorine gas into pure water, and the logarithmic value of bacteria removal is 4-7.

9. The use according to claim 8, characterized in that: The synthesized metal-based MOF was loaded on carbon cloth as the working electrode, a saturated calomel electrode was used as the reference electrode, and a carbon rod was used as the counter electrode to form a three-electrode system.

10. The use according to claim 8, characterized in that: The saline solution is prepared by adjusting the pH of a 4M NaCl solution to 1-3 using hydrochloric acid, sulfuric acid or perchloric acid.

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