A nano-nickel copper hydroxy oxide electrode and a method for electrolytic treatment of ammonia-containing wastewater
By heating the nano-nickel copper hydroxide electrode in the reaction solution of hydroxide and persulfate to convert it into a nano-nickel copper hydroxyoxide electrode, the problems of poor catalytic activity of the anode material and high resistance in the electrode in the prior art are solved, and the ammonia in the ammonia-containing wastewater is efficiently removed, so that the product is pure and the secondary pollution is small.
Patent Information
- Application Number
- CN202310562422.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-05-18
- Publication Date
- 2025-06-13
- Estimated Expiration
- 2043-05-18
AI Technical Summary
In the existing electrolytic treatment of ammonia-containing wastewater, the anode material has poor catalytic activity and requires a high overpotential to achieve ammonia removal. It is difficult to maintain nanomorphology and high conductivity for direct preparation of nickel-copper hydroxyoxide electrodes.
By placing the hydroxide and persulfate into a reaction solution, the nano nickel copper hydroxide electrode is soaked in the solution and heated to react, and converted to the nano nickel copper hydroxyoxide electrode. This method has both nanomorphology, improves interface contact ratio, high nickel copper hydroxyoxide content, and partially retains nanostructures, reducing the resistance in the electrode.
It significantly improves the performance of electro-oxidized ammonia, and has high efficiency in treating ammonia-containing wastewater. The products are mainly nitrogen and have little secondary pollution.
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Figure CN116589044B_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of wastewater treatment, and particularly relates to a nano nickel-copper hydroxy oxide electrode and a method for electrolytic treatment of ammonia-containing wastewater. Background Art
[0002] Ammonia is one of the common pollutants widely present in wastewater. It is not only discharged in large quantities by industries, but also the main pollutant in the wastewater discharged from human life and livestock and poultry breeding industries. Its entry into the environment can induce eutrophication of water bodies and endanger the aquatic environment, and it can also be converted into nitrate to endanger human health. Although traditional biological methods can effectively remove ammonia, considering the problem that it is difficult to cover large-scale treatment facilities due to the wide distribution of pollution sources (such as small-scale breeding in rural areas, domestic sewage in scenic spots and small-scale inhabited areas), there is still an urgent need for a new treatment method with simple process equipment, easy operation control and small floor area.
[0003] In the electrooxidation process, ammonia can be directly decomposed through anodic oxidation reaction to convert it into nitrogen gas, achieving the removal of ammonia without generating secondary pollution. And electrochemical water treatment equipment is smaller in volume, smaller in floor area, easier to operate, and can be started and stopped at any time compared with biological treatment and other technologies, thus having a better targeted application scenario. Therefore, electrolytic treatment of ammonia-containing wastewater is an important supplement to the existing ammonia-containing wastewater treatment technology. The theoretical potential of this reaction process is only 0.06V, but due to the poor catalytic activity of general anode materials for this reaction, a relatively high overpotential is usually required to achieve the removal of ammonia, thus limiting the application of this technology. It can be seen that developing an efficient ammonia removal electrode by electrolysis is the key point to promote the development of this technology.
[0004] At the same time, the production cost of the electrode should also be considered. Cost is an important factor restricting the practical application of a technology. Cost is generally considered to consist of two aspects: raw material cost and preparation process cost. From the perspective of raw material cost, nickel-copper bimetallic electrodes have recently been found to be effective materials for electrolyzing ammonia. As transition metals, nickel and copper are relatively low in price, only 1 / 1000 of the traditional platinum electrode, with obvious advantages.
[0005] Recently, nickel-copper hydroxide electrodes with nanoscale dimensions have been found to have excellent performance. Theoretical studies have shown (Electrodeposited NiCu bimetal on carbon paper as stable non-noble anode for efficient electrooxidation of ammonia, 《Applied Catalysis B: Environmental》) that when the nanoscale nickel-copper hydroxide electrode is used for ammonia electrolysis, a thin layer of nickel-copper hydroxyoxide is formed on its surface, and these in-situ transformed nickel-copper hydroxyoxides are the actual reaction sites that play a catalytic role. However, the content of nickel-copper hydroxyoxide in-situ transformed during the electrooxidation process is low and the crystallinity is poor, which limits its performance. Direct preparation of nickel-copper hydroxyoxide electrodes is difficult to maintain the nanoscale morphology of the nanoscale nickel-copper hydroxide electrode, and the directly prepared nickel-copper hydroxyoxide electrodes usually have poor electrical conductivity and large internal resistance, and their ammonia electrolysis performance is also limited. Summary of the Invention
[0006] In view of this, the purpose of the present invention is to provide a nanoscale nickel-copper hydroxyoxide electrode and a method for electrolytic treatment of ammonia-containing wastewater, which can convert the nanoscale nickel-copper hydroxide electrode into a nanoscale nickel-copper hydroxyoxide electrode and solve the defects of in-situ transformation or direct preparation of nickel-copper hydroxyoxide electrodes during the electrooxidation process.
[0007] To achieve the above purpose, the present invention provides the following technical solutions:
[0008] The present invention discloses a preparation method of a nanoscale nickel-copper hydroxyoxide electrode, comprising the following steps:
[0009] (1) Mix hydroxide and persulfate in water to prepare a reaction solution;
[0010] (2) Immerse the nanoscale nickel-copper hydroxide electrode in the reaction solution prepared in step (1), and after heating and reacting, obtain the nanoscale nickel-copper hydroxyoxide electrode.
[0011] As a preferred technical solution, in step (1), the hydroxide is one or a mixture of two of sodium hydroxide and potassium hydroxide, and the concentration of the hydroxide in the reaction solution is 0.1 g / L - 200 g / L.
[0012] As a preferred technical solution, in step (1), the concentration of the hydroxide in the reaction solution is 10 g / L - 40 g / L.
[0013] As a preferred technical solution, in the step (1), the persulfate is one or a mixture of several of potassium monopersulfate, potassium persulfate, and sodium persulfate, and the concentration of the persulfate in the reaction solution is 0.1 g / L - 24 g / L.
[0014] As a preferred technical solution, in the step (1), the concentration of the persulfate in the reaction solution is 5 g / L - 12 g / L.
[0015] As a preferred technical solution, in the step (2), the heating reaction temperature is 60 - 90 °C, and the reaction time is 0.5 - 4 h.
[0016] As a preferred technical solution, the preparation method of the nano nickel - copper hydroxide electrode is as follows: nickel salt and copper salt are mixed and subjected to a hydrothermal reaction to generate nano nickel - copper hydroxide, and then the nano nickel - copper hydroxide is coated on the substrate electrode; or the substrate electrode is immersed in a mixed solution of nickel salt and copper salt for hydrothermal reaction to in - situ grow nano nickel - copper hydroxide on the substrate electrode.
[0017] The present invention also discloses a nano nickel - copper hydroxyoxide electrode prepared by the above - mentioned preparation method.
[0018] The present invention also discloses a method for electrolytic treatment of ammonia - containing wastewater using a nano nickel - copper hydroxyoxide electrode. The nano nickel - copper hydroxyoxide electrode is used as the anode and connected to an electrolytic cell, and the ammonia - containing wastewater is poured into the electrolytic cell. A positive voltage is applied to the nano nickel - copper hydroxyoxide electrode to electrolytically remove ammonia from the wastewater.
[0019] As a preferred technical solution, the positive voltage applied to the nano nickel - copper hydroxyoxide electrode in the electrolytic cell is 0.4 - 10 V based on a saturated calomel reference electrode.
[0020] The beneficial effects of the present invention are as follows:
[0021] The present invention discovers that by configuring a reaction solution with hydroxide and persulfate, the nano nickel - copper hydroxide electrode can be transformed into a nano nickel - copper hydroxyoxide electrode, and this method solves the defects of in - situ transformation or direct preparation of nickel - copper hydroxyoxide electrodes in the electro - oxidation process, forming a new type of nano nickel - copper hydroxyoxide electrode that combines a nano - morphology to increase the interfacial contact ratio, a high content of nickel - copper hydroxyoxide to increase the number of reaction sites, and a partially retained internal structure of nano nickel - copper hydroxide to reduce the internal resistance of the electrode.
[0022] The ammonia - electrolysis performance of the nano nickel - copper hydroxyoxide electrode of the present invention is greatly improved compared with that before treatment. It is highly efficient in treating ammonia - containing wastewater, with the main product being nitrogen and little secondary pollution. Description of the Drawings
[0023] To make the objectives, technical solutions and beneficial effects of the present invention clearer, the present invention provides the following attached drawings for illustration:
[0024] Figure 1 XRD diagrams of nickel-copper hydroxide without being treated by the method of the present invention, nickel-copper hydroxyoxide after treatment and conversion, and over-treated nickel-copper hydroxyoxide.
[0025] Figure 2 SEM diagrams of nickel-copper hydroxide without being treated by the method of the present invention, nickel-copper hydroxyoxide after treatment and conversion, and over-treated nickel-copper hydroxyoxide.
[0026] Figure 3 Current response diagrams of nickel-copper hydroxide without being treated by the method of the present invention, nickel-copper hydroxyoxide after treatment and conversion, and over-treated nickel-copper hydroxyoxide in the same ammonia-containing wastewater. Detailed implementation manners
[0027] The present invention will be further described below in conjunction with the attached drawings and specific embodiments, so that those skilled in the art can better understand the present invention and be able to implement it, but the exemplified embodiments are not intended to limit the present invention.
[0028] Example 1
[0029] (1) Synthesize a nano nickel-copper hydroxide electrode grown in-situ on the surface of carbon cloth
[0030] Weigh 0.4206 g of nickel sulfate, 0.0966 g of copper nitrate and 150 mg of urea, add them to 40 ml of high-purity water and stir until dissolved. Pour the dissolved solution into a high-temperature reaction kettle, and place a 1 cm 2 carbon cloth as the base electrode at the bottom of the reaction kettle, and put it into an oven at a constant temperature of 120 °C for hydrothermal treatment for 6 h. After the reaction is completed, take out the carbon cloth loaded with nano nickel-copper hydroxide, rinse and dry it, and this is the nano nickel-copper hydroxide electrode.
[0031] (2) Prepare a treated nano nickel-copper hydroxyoxide electrode
[0032] Prepare a reaction solution. Weigh 0.6 g of potassium persulfate and 2 g of solid sodium hydroxide, put them into a beaker, add 50 ml of deionized water and stir until dissolved to obtain a clear reaction solution. It can be known that the concentration of potassium persulfate in this solution is 12 g / L, and the concentration of sodium hydroxide is 40 g / L. Immerse the electrode obtained in step (1) in the reaction solution, place the beaker in a water bath, and carry out hydrothermal treatment at a constant temperature of 60 °C for 2 h. Then take it out, wash and dry it, and obtain the treated nano nickel-copper hydroxyoxide electrode, named NiCuOOH-1.
[0033] Example 2
[0034] (1) Nano nickel - copper hydroxide electrode grown in - situ on the surface of synthetic carbon cloth
[0035] Weigh 0.4206 g of nickel sulfate, 0.0966 g of copper nitrate and 150 mg of urea, add them to 40 ml of high - purity water and stir until dissolved. Pour the dissolved solution into a high - temperature reaction kettle, and place a 1 - cm 2 carbon cloth as the base electrode at the bottom of the reaction kettle. Put it into an oven and carry out hydrothermal reaction at a constant temperature of 120 °C for 6 h. After the reaction is completed, take out the carbon cloth loaded with nano nickel - copper hydroxide, rinse and dry it. This is the nano nickel - copper hydroxide electrode.
[0036] (2) Preparation of over - treated nano nickel - copper hydroxy - oxide electrode
[0037] Prepare the reaction solution. Weigh 1.2 g of potassium persulfate and 10 g of sodium hydroxide solid, put them into a beaker, add 50 ml of deionized water and stir until dissolved to obtain a clear reaction solution. It can be known that the concentration of potassium persulfate in this solution is 24 g / L and the concentration of sodium hydroxide is 200 g / L. Immerse the electrode obtained in step (1) in the reaction solution, place the beaker in a water - bath kettle, and carry out a water - bath at a constant temperature of 60 °C for 2 h. Then take it out, wash and dry it to obtain the over - treated nano nickel - copper hydroxy - oxide electrode, named NiCuOOH - 2.
[0038] Comparative Example 1
[0039] (1) Synthesis of untreated nano nickel - copper hydroxide electrode
[0040] Weigh 0.4206 g of nickel sulfate, 0.0966 g of copper nitrate and 150 mg of urea, add them to 40 ml of high - purity water and stir until dissolved. Pour the dissolved solution into a high - temperature reaction kettle, and place a 1 - cm 2 carbon cloth as the base electrode at the bottom of the reaction kettle. Put it into an oven and carry out hydrothermal reaction at a constant temperature of 120 °C for 6 h. After the reaction is completed, take out the carbon cloth loaded with nano nickel - copper hydroxide, rinse and dry it. This is the nano nickel - copper hydroxide electrode, named NiCu(OH) 2 .
[0041] Use an X - ray diffractometer to analyze the electrodes obtained in Example 1, Example 2 and Comparative Example 1. The results are as Figure 1 shown. By observing the crystallization peaks, it can be confirmed that nano nickel - copper hydroxide was successfully synthesized in Comparative Example 1. And the crystallization peaks of NiCuOOH - 1 in Example 1 after water - bath treatment and NiCu(OH) in Comparative Example 1 2Completely different, the peaks belonging to nickel - copper hydroxide mostly disappear while the peaks belonging to nickel - copper oxyhydroxide appear. This trend is more obvious in the XRD pattern of NiCuOOH - 2 in Example 2. The peaks belonging to nickel - copper hydroxide are almost invisible, while the intensity and sharpness of the peaks belonging to nickel - copper oxyhydroxide both increase. This phenomenon indicates that the treatment method of the present invention has successfully converted nickel - copper hydroxide into nickel - copper oxyhydroxide.
[0042] The electrodes obtained in Example 1, Example 2 and Comparative Example 1 were analyzed by scanning electron microscopy, and the results are as Figure 2 shown. It can be seen that all three electrodes have a nano - morphology. After being treated and converted into nickel - copper oxyhydroxide, NiCuOOH - 1 and NiCuOOH - 2 still retain a nano - structure similar to that of Comparative Example 1.
[0043] Example 1, Example 2 and Comparative Example 1 were used as working electrodes and placed in an electrolytic cell respectively, and a platinum sheet cathode, a saturated calomel reference electrode and an electrochemical workstation were connected to form a closed circuit. Electrochemical linear voltammetry scanning was carried out in a simulated wastewater of 0.1M KOH + 0.1M NH 3 As the applied positive voltage gradually increased, the results are as Figure 3 shown. The oxidation current of Example 1 is significantly higher than that of Example 2 and Comparative Example 1, indicating that the ability of NiCuOOH - 1 in Example 1 to electro - oxidize ammonia is significantly stronger than that of Example 2 and Comparative Example 1. This shows that the nickel - copper oxyhydroxide electrode obtained by the treatment method of the present invention has a significantly improved performance compared with the electrode before treatment. At the same time, there is an optimal range for this treatment method, and the performance of the sample obtained after excessive increase of the reaction solution concentration will decline.
[0044] The electrodes of Example 1, Example 2 and Comparative Example 1 were used as anodes and placed in a single - cell electrolytic cell respectively, and a platinum sheet cathode, a saturated calomel reference electrode and a regulated power supply were connected to form a closed circuit. Wastewater with a high ammonia - nitrogen concentration of 1400mg / L and a pH of 13, which is difficult to be biologically treated, was added to the electrolytic cell. The regulated power supply was started, and a voltage of 0.5V was applied to the anode. The ammonia - nitrogen concentration in the wastewater was sampled and detected over time, and the results are shown in Table 1. It can be seen that the ability of NiCuOOH - 1 in Example 1 to electro - oxidize ammonia is significantly stronger than that of Comparative Example 1 and also stronger than that of Example 2.
[0045] Table 1 Changes in ammonia concentration during electro - catalytic oxidation treatment of ammonia - containing wastewater in a single - cell electrolytic cell
[0046] Time (h) NiCuOOH-1 (Example 1) NiCuOOH-2 (Example 2) <![CDATA[NiCu(OH) 2 (Comparative Example 1)]]> 0 1400 mg / L 1400 mg / L 1400 mg / L 1 1043 mg / L 1125 mg / L 1256 mg / L 2 862 mg / L 951 mg / L 1125 mg / L 4 647 mg / L 786 mg / L 942 mg / L 6 497 mg / L 664 mg / L 783 mg / L 8 389 mg / L 553 mg / L 650 mg / L 10 365 mg / L 489 mg / L 568 mg / L
[0047] The above-described embodiments are only preferred embodiments given to fully illustrate the present invention, and the protection scope of the present invention is not limited thereto. Equivalent substitutions or transformations made by those skilled in the art on the basis of the present invention are within the protection scope of the present invention. The protection scope of the present invention is subject to the claims.
Claims
1. A preparation method of a nano nickel - copper hydroxy - oxide electrode, characterized in that: it includes the following steps: (1) Mix hydroxide and persulfate in water to prepare a reaction solution; (2) Immerse the nano nickel - copper hydroxide electrode in the reaction solution prepared in step (1), and after heating and reacting, obtain the nano nickel - copper hydroxy - oxide electrode.
2. The preparation method of the nano nickel - copper hydroxy - oxide electrode according to claim 1, characterized in that: in the said step (1), the hydroxide is one or a mixture of two of sodium hydroxide and potassium hydroxide, and the concentration of the hydroxide in the reaction solution is 0.1 g / L - 200 g / L.
3. The preparation method of the nano nickel - copper hydroxy - oxide electrode according to claim 2, characterized in that: in the said step (1), the concentration of the hydroxide in the reaction solution is 10 g / L - 40 g / L.
4. The preparation method of the nano nickel - copper hydroxy - oxide electrode according to claim 1, characterized in that: in the said step (1), the persulfate is one or a mixture of several of potassium monopersulfate, potassium persulfate, and sodium persulfate, and the concentration of the persulfate in the reaction solution is 0.1 g / L - 24 g / L.
5. The preparation method of the nano nickel - copper hydroxy - oxide electrode according to claim 4, characterized in that: in the said step (1), the concentration of the persulfate in the reaction solution is 5 g / L - 12 g / L.
6. The preparation method of the nano nickel - copper hydroxy - oxide electrode according to claim 1, characterized in that: in the said step (2), the heating reaction temperature is 60 - 90 °C, and the reaction time is 0.5 - 4 h.
7. The preparation method of the nano nickel - copper hydroxy - oxide electrode according to any one of claims 1 to 6, characterized in that: the preparation method of the said nano nickel - copper hydroxide electrode is: mix nickel salt and copper salt for hydrothermal reaction to generate nano nickel - copper hydroxide, and then coat the nano nickel - copper hydroxide on the substrate electrode; or immerse the substrate electrode in the mixed solution of nickel salt and copper salt for hydrothermal reaction to in - situ grow nano nickel - copper hydroxide on the substrate electrode.
8. The nano nickel - copper hydroxy - oxide electrode prepared by the preparation method according to any one of claims 1 to 7.
9. A method for electrolytic treatment of ammonia - containing wastewater using a nano nickel - copper hydroxy - oxide electrode, characterized in that: use the nano nickel - copper hydroxy - oxide electrode according to claim 8 as the anode and connect it to an electrolytic cell, pour the ammonia - containing wastewater into the electrolytic cell, apply a positive voltage to the nano nickel - copper hydroxy - oxide electrode, and electrolytically remove ammonia in the wastewater.
10. The method for electrolytic treatment of ammonia - containing wastewater using a nano nickel - copper hydroxy - oxide electrode according to claim 9, characterized in that: the positive voltage applied to the nano nickel - copper hydroxy - oxide electrode in the electrolytic cell is 0.4 - 10 V based on a saturated calomel reference electrode.