CN115465923B - Method for treating nitrate wastewater by copper-nickel alloy three-dimensional composite electrode loaded with copper hydroxide - Google Patents
Method for treating nitrate wastewater by copper-nickel alloy three-dimensional composite electrode loaded with copper hydroxide Download PDFInfo
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- CN115465923B CN115465923B CN202210900715.7A CN202210900715A CN115465923B CN 115465923 B CN115465923 B CN 115465923B CN 202210900715 A CN202210900715 A CN 202210900715A CN 115465923 B CN115465923 B CN 115465923B
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- 229910002651 NO3 Inorganic materials 0.000 title claims abstract description 116
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 title claims abstract description 116
- JJLJMEJHUUYSSY-UHFFFAOYSA-L Copper hydroxide Chemical compound [OH-].[OH-].[Cu+2] JJLJMEJHUUYSSY-UHFFFAOYSA-L 0.000 title claims abstract description 103
- 239000005750 Copper hydroxide Substances 0.000 title claims abstract description 103
- 229910001956 copper hydroxide Inorganic materials 0.000 title claims abstract description 103
- 229910000570 Cupronickel Inorganic materials 0.000 title claims abstract description 86
- 229910045601 alloy Inorganic materials 0.000 title claims abstract description 86
- 239000000956 alloy Substances 0.000 title claims abstract description 86
- YOCUPQPZWBBYIX-UHFFFAOYSA-N copper nickel Chemical compound [Ni].[Cu] YOCUPQPZWBBYIX-UHFFFAOYSA-N 0.000 title claims abstract description 86
- 239000002351 wastewater Substances 0.000 title claims abstract description 71
- 239000011165 3D composite Substances 0.000 title claims abstract description 69
- 238000000034 method Methods 0.000 title claims abstract description 64
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims abstract description 108
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 54
- 238000011282 treatment Methods 0.000 claims abstract description 54
- 230000009467 reduction Effects 0.000 claims abstract description 40
- 229910052802 copper Inorganic materials 0.000 claims abstract description 32
- 239000010949 copper Substances 0.000 claims abstract description 32
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims abstract description 31
- 239000000758 substrate Substances 0.000 claims abstract description 28
- 229910052751 metal Inorganic materials 0.000 claims abstract description 25
- 239000002184 metal Substances 0.000 claims abstract description 25
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 21
- 239000002070 nanowire Substances 0.000 claims abstract description 18
- 239000002245 particle Substances 0.000 claims abstract description 12
- 239000011259 mixed solution Substances 0.000 claims description 30
- 150000001879 copper Chemical class 0.000 claims description 24
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 18
- 239000006260 foam Substances 0.000 claims description 17
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 14
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical group [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 claims description 13
- MMDJDBSEMBIJBB-UHFFFAOYSA-N [O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O.[NH6+3] Chemical compound [O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O.[NH6+3] MMDJDBSEMBIJBB-UHFFFAOYSA-N 0.000 claims description 13
- 229910052938 sodium sulfate Inorganic materials 0.000 claims description 13
- 235000011152 sodium sulphate Nutrition 0.000 claims description 13
- 239000000243 solution Substances 0.000 claims description 13
- DDFHBQSCUXNBSA-UHFFFAOYSA-N 5-(5-carboxythiophen-2-yl)thiophene-2-carboxylic acid Chemical compound S1C(C(=O)O)=CC=C1C1=CC=C(C(O)=O)S1 DDFHBQSCUXNBSA-UHFFFAOYSA-N 0.000 claims description 12
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 claims description 12
- 239000004202 carbamide Substances 0.000 claims description 12
- 238000002360 preparation method Methods 0.000 claims description 12
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical group [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims description 10
- 238000006243 chemical reaction Methods 0.000 claims description 10
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 claims description 9
- 238000001027 hydrothermal synthesis Methods 0.000 claims description 9
- HJPBEXZMTWFZHY-UHFFFAOYSA-N [Ti].[Ru].[Ir] Chemical compound [Ti].[Ru].[Ir] HJPBEXZMTWFZHY-UHFFFAOYSA-N 0.000 claims description 7
- 239000012535 impurity Substances 0.000 claims description 7
- 230000008569 process Effects 0.000 claims description 7
- 239000003792 electrolyte Substances 0.000 claims description 6
- 238000004140 cleaning Methods 0.000 claims description 5
- 239000011780 sodium chloride Substances 0.000 claims description 5
- 238000002156 mixing Methods 0.000 claims description 3
- 150000003841 chloride salts Chemical class 0.000 claims description 2
- ORTQZVOHEJQUHG-UHFFFAOYSA-L copper(II) chloride Chemical compound Cl[Cu]Cl ORTQZVOHEJQUHG-UHFFFAOYSA-L 0.000 claims description 2
- XTVVROIMIGLXTD-UHFFFAOYSA-N copper(II) nitrate Chemical group [Cu+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O XTVVROIMIGLXTD-UHFFFAOYSA-N 0.000 claims description 2
- 230000035484 reaction time Effects 0.000 claims description 2
- 238000011946 reduction process Methods 0.000 claims 1
- 230000000694 effects Effects 0.000 abstract description 21
- IOVCWXUNBOPUCH-UHFFFAOYSA-M Nitrite anion Chemical compound [O-]N=O IOVCWXUNBOPUCH-UHFFFAOYSA-M 0.000 abstract description 19
- 239000010842 industrial wastewater Substances 0.000 abstract description 5
- 239000010865 sewage Substances 0.000 abstract description 3
- 238000006722 reduction reaction Methods 0.000 description 35
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 18
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 14
- 239000001257 hydrogen Substances 0.000 description 13
- 229910052739 hydrogen Inorganic materials 0.000 description 13
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 10
- 239000010406 cathode material Substances 0.000 description 9
- 229910052757 nitrogen Inorganic materials 0.000 description 9
- 239000007864 aqueous solution Substances 0.000 description 7
- 239000011230 binding agent Substances 0.000 description 7
- SXTLQDJHRPXDSB-UHFFFAOYSA-N copper;dinitrate;trihydrate Chemical compound O.O.O.[Cu+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O SXTLQDJHRPXDSB-UHFFFAOYSA-N 0.000 description 7
- XKMRRTOUMJRJIA-UHFFFAOYSA-N ammonia nh3 Chemical compound N.N XKMRRTOUMJRJIA-UHFFFAOYSA-N 0.000 description 6
- 230000027756 respiratory electron transport chain Effects 0.000 description 6
- 230000007613 environmental effect Effects 0.000 description 5
- 229910003445 palladium oxide Inorganic materials 0.000 description 5
- 229910021642 ultra pure water Inorganic materials 0.000 description 5
- 239000012498 ultrapure water Substances 0.000 description 5
- 239000000463 material Substances 0.000 description 4
- 238000004064 recycling Methods 0.000 description 4
- 238000002791 soaking Methods 0.000 description 4
- 238000001179 sorption measurement Methods 0.000 description 4
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 3
- 125000004122 cyclic group Chemical group 0.000 description 3
- 230000007547 defect Effects 0.000 description 3
- 150000002431 hydrogen Chemical class 0.000 description 3
- 239000013067 intermediate product Substances 0.000 description 3
- 238000011068 loading method Methods 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 2
- 238000009825 accumulation Methods 0.000 description 2
- 239000004480 active ingredient Substances 0.000 description 2
- 239000006227 byproduct Substances 0.000 description 2
- 239000000460 chlorine Substances 0.000 description 2
- 229910052801 chlorine Inorganic materials 0.000 description 2
- 230000006378 damage Effects 0.000 description 2
- 238000000151 deposition Methods 0.000 description 2
- 239000007772 electrode material Substances 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- WQYVRQLZKVEZGA-UHFFFAOYSA-N hypochlorite Chemical compound Cl[O-] WQYVRQLZKVEZGA-UHFFFAOYSA-N 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 230000001404 mediated effect Effects 0.000 description 2
- 238000001000 micrograph Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 229910052763 palladium Inorganic materials 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 230000001737 promoting effect Effects 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 1
- 239000005751 Copper oxide Substances 0.000 description 1
- 241000282414 Homo sapiens Species 0.000 description 1
- JVMRPSJZNHXORP-UHFFFAOYSA-N ON=O.ON=O.ON=O.N Chemical compound ON=O.ON=O.ON=O.N JVMRPSJZNHXORP-UHFFFAOYSA-N 0.000 description 1
- 239000002033 PVDF binder Substances 0.000 description 1
- 239000006230 acetylene black Substances 0.000 description 1
- 230000006978 adaptation Effects 0.000 description 1
- 239000012670 alkaline solution Substances 0.000 description 1
- 238000009903 catalytic hydrogenation reaction Methods 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 150000001804 chlorine Chemical class 0.000 description 1
- -1 chlorine ions Chemical class 0.000 description 1
- 229910000431 copper oxide Inorganic materials 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 230000005518 electrochemistry Effects 0.000 description 1
- 238000004070 electrodeposition Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000003673 groundwater Substances 0.000 description 1
- 238000005342 ion exchange Methods 0.000 description 1
- 244000144972 livestock Species 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 230000000813 microbial effect Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000000618 nitrogen fertilizer Substances 0.000 description 1
- 235000015097 nutrients Nutrition 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- PIBWKRNGBLPSSY-UHFFFAOYSA-L palladium(II) chloride Chemical compound Cl[Pd]Cl PIBWKRNGBLPSSY-UHFFFAOYSA-L 0.000 description 1
- 238000011197 physicochemical method Methods 0.000 description 1
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 1
- 238000001223 reverse osmosis Methods 0.000 description 1
- 239000010802 sludge Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 230000003313 weakening effect Effects 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
- C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
- C02F1/467—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis by electrochemical disinfection; by electrooxydation or by electroreduction
- C02F1/4676—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis by electrochemical disinfection; by electrooxydation or by electroreduction by electroreduction
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
- C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
- C02F1/46104—Devices therefor; Their operating or servicing
- C02F1/46109—Electrodes
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
- C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
- C02F1/46104—Devices therefor; Their operating or servicing
- C02F1/46109—Electrodes
- C02F2001/46133—Electrodes characterised by the material
- C02F2001/46138—Electrodes comprising a substrate and a coating
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/10—Inorganic compounds
- C02F2101/16—Nitrogen compounds, e.g. ammonia
- C02F2101/163—Nitrates
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/10—Inorganic compounds
- C02F2101/16—Nitrogen compounds, e.g. ammonia
- C02F2101/166—Nitrites
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Organic Chemistry (AREA)
- Water Treatment By Electricity Or Magnetism (AREA)
Abstract
The invention discloses a method for treating nitrate wastewater by using a copper-nickel alloy three-dimensional composite electrode loaded with copper hydroxide, which takes the copper-nickel alloy three-dimensional composite electrode loaded with copper hydroxide as a cathode to carry out electrochemical reduction treatment on the nitrate wastewater, wherein the copper-nickel alloy three-dimensional composite electrode loaded with copper hydroxide comprises a nickel metal substrate, copper particles growing on the nickel metal substrate and copper hydroxide nanowires. According to the method, the copper-nickel alloy three-dimensional composite electrode loaded with copper hydroxide and having high reducing capability and high stability is used as the cathode, so that the efficient reduction of nitrate wastewater can be realized, nitrite can be effectively removed, and the method has the advantages of low treatment cost, high treatment efficiency, good removal effect, environment friendliness and the like, is a method which can be widely adopted, can efficiently remove nitrate in water, has high use value and good application prospect, and has important significance for effectively removing nitrate in urban sewage, underground water and industrial wastewater.
Description
Technical Field
The invention belongs to the technical field of environmental electrochemistry, relates to a method for treating nitrate wastewater by using an electrochemical reduction method, and in particular relates to a method for treating nitrate wastewater by using a copper-nickel alloy three-dimensional composite electrode loaded with copper hydroxide.
Background
Sources of nitrate pollution in water mainly comprise industrial wastewater discharge, large-scale use of nitrogen fertilizer, livestock wastewater discharge, municipal sludge and the like, and meanwhile, a large amount of nitrate pollution enters the water and can bring serious harm to the ecological environment of the water and human beings. Currently, technologies for treating nitrate wastewater include: biological, physicochemical, chemical, etc., where biological treatment processes typically require additional nutrients and appropriate environmental conditions to meet microbial growth, and are thus unsuitable for removal of nitrate pollution in groundwater and industrial wastewater; the physicochemical method mainly comprises ion exchange and reverse osmosis, but the two methods only separate nitrate from water, so that the nitrate cannot be thoroughly removed, and the generated high-concentration nitrate wastewater needs further treatment, thus easily bringing secondary pollution; in the chemical method, the catalytic hydrogenation method is commonly used, but the production, transportation and storage of hydrogen used in the method are a great difficulty at present, which limits the application of the chemical method in treating nitrate wastewater. In contrast, the electrochemical reduction method directly or indirectly reduces nitrate by utilizing electrons of a green reducing agent, and thoroughly damages the nitrate, so that high-concentration nitrate wastewater is not generated, but the electrochemical reduction method mainly reduces nitrate into byproducts such as nitrite, ammonia nitrogen and the like, and secondary pollution is still caused by the existence of the byproducts in water. In addition, the cathode materials used in the existing electrochemical reduction method still have the following defects: the specific surface area is small, the active sites are few, the reduction efficiency of nitrate is poor, and the improvement of the treatment efficiency and the removal rate is not facilitated; the active ingredients are easy to separate from or fall off from the substrate material, so that the number of active sites of the cathode material is further reduced, the long-term stability of the reduction effect of the cathode material is not facilitated to be maintained, and the active ingredients entering the water body are easy to bring new pollution; the preparation cost of the cathode material is high, which is not beneficial to reducing the treatment cost. Therefore, the cathode material with low cost, strong reducing capability and high stability is obtained, and has important significance for thoroughly removing nitrate in water with low cost and high efficiency.
Disclosure of Invention
The invention aims to solve the technical problem of overcoming the defects of the prior art and providing a method for treating nitrate wastewater by using a copper-nickel alloy three-dimensional composite electrode loaded with copper hydroxide, which has the advantages of low treatment cost, high treatment efficiency, good removal effect and environmental protection.
In order to solve the technical problems, the invention adopts the following technical scheme.
A method for treating nitrate wastewater by using copper-nickel alloy three-dimensional composite electrode loaded with copper hydroxide comprises the steps of carrying out electrochemical reduction treatment on nitrate wastewater by using the copper-nickel alloy three-dimensional composite electrode loaded with copper hydroxide as a cathode; the copper-nickel alloy three-dimensional composite electrode loaded with copper hydroxide comprises a nickel metal substrate, wherein copper particles and copper hydroxide nanowires are grown on the nickel metal substrate.
In the above method, further improved, the nickel metal substrate is any one of nickel plate, nickel mesh and foam nickel.
The method for preparing the copper-nickel alloy three-dimensional composite electrode loaded with copper hydroxide is further improved, and comprises the following steps of:
s1, mixing a nickel metal substrate with a mixed solution of copper salt, ammonium fluoride and urea to obtain a mixed solution; the concentration of copper salt in the mixed solution is more than 2.4g/L;
s2, carrying out hydrothermal reaction on the mixed solution obtained in the step S1 to obtain the copper-nickel alloy three-dimensional composite electrode loaded with copper hydroxide.
In the above method, further improved, in step S1, the concentration of copper salt in the mixed solution is 3g/L to 9.6g/L.
In the above method, further improved, in step S1, the concentration of copper salt in the mixed solution is 4g/L to 8g/L.
In a further improvement of the above method, in step S1, the nickel metal substrate further includes the following treatments before use: sequentially adopting ethanol, hydrochloric acid solution and water for cleaning treatment to remove surface oxides and impurities; the concentration of the hydrochloric acid solution is 0.5 mol/L-1 mol/L; the concentration of ammonium fluoride in the mixed solution is 1.5 g/L-2 g/L, and the concentration of urea is 6 g/L-8 g/L; the mixed solution of copper salt, ammonium fluoride and urea is prepared by dissolving copper salt, ammonium fluoride and urea into water; the copper salt is copper nitrate and/or copper chloride.
In the above method, further improved, in step S2, the hydrothermal reaction is performed in an autoclave; the temperature of the hydrothermal reaction is 105-150 ℃; the hydrothermal reaction time is 4-6 h.
The above method, further improved, wherein the electrochemical reduction treatment process further comprises: adding electrolyte into nitrate wastewater to ensure that the concentration of the electrolyte in the system is 0.05mol/L to 0.1mol/L; the electrolyte is sodium sulfate.
The above method, further improved, wherein the electrochemical reduction treatment process further comprises: adding chloride into the nitrate wastewater to ensure that the concentration of the chloride in the system is 0.5g/L; the chloride salt is sodium chloride.
In the method, the ruthenium iridium titanium electrode is used as an anode in the electrochemical reduction treatment process.
The above method, further improved, wherein the electrochemical reduction treatment is performed under constant current conditions; the current density is controlled to be 6mA/cm in the electrochemical reduction treatment process 2 ～20mA/cm 2 The method comprises the steps of carrying out a first treatment on the surface of the The electrochemical reduction treatment time is 1.5-3 h.
According to the method, the concentration of the nitrate wastewater is less than or equal to 100mg/L based on nitrate nitrogen.
The method is further improved, and after the electrochemical reduction treatment is finished, the method further comprises the following steps: and (3) repeatedly performing electrochemical reduction treatment on the nitrate wastewater by taking the copper-nickel alloy three-dimensional composite electrode loaded with copper hydroxide as a cathode, wherein the repetition times are 1-20 times.
Compared with the prior art, the invention has the advantages that:
(1) Aiming at the defects of high treatment cost, low treatment efficiency, easiness in causing secondary pollution and the like of the existing electrochemical reduction method, the invention creatively provides a method for treating nitrate wastewater by using a copper-nickel alloy three-dimensional composite electrode loaded with copper hydroxide. In the invention, when the copper-nickel alloy three-dimensional composite electrode loaded with copper hydroxide is used as a cathode, cu and Cu on the surface of the electrode can be utilized in a reactor 2 The O-mediated electron transfer function can quickly reduce nitrate in water into nitrite, ammonia nitrogen, nitrogen and other products, meanwhile, the copper hydroxide nanowire is loaded, so that the electrode has higher specific surface area and more positive charges, the active site on the surface of the electrode and the adsorption function on nitrate and nitrite can be increased, reduction of nitrate and nitrite is facilitated, meanwhile, the nickel metal substrate serving as a good hydrogen evolution material can generate a large amount of active hydrogen in electrochemical reduction of nitrate, and therefore, exposure of nickel substrate sites in the three-dimensional composite electrode can generate a large amount of active hydrogen, thereby promoting reduction of nitrite. Compared with the conventional cathode material, the copper-nickel alloy three-dimensional composite electrode loaded with copper hydroxide adopted in the invention has two ways of reducing nitrate at the same time, and can be used forThe nitrate is reduced by the electron transfer on the surface of the cathode, and is reduced by the active hydrogen generated by the cathode, and the method has the advantages of high electron transfer rate, strong nitrate and nitrite adsorption capacity, strong active hydrogen production capacity and the like, thereby being more beneficial to electrochemical reduction of the nitrate; more importantly, the copper particles and the copper hydroxide nanowires can stably grow on the surface of the nickel metal substrate, so that the electrode has excellent stability, can be repeatedly used for treating nitrate wastewater, can remarkably reduce the treatment cost, and can not bring secondary pollution. Therefore, the method for treating the nitrate wastewater by using the copper-nickel alloy three-dimensional composite electrode loaded with copper hydroxide has the advantages of low treatment cost, high treatment efficiency, good removal effect, environmental protection and the like, can be widely adopted, can effectively remove nitrate in water, can realize the efficient treatment of the nitrate wastewater, has high removal rate of nitrite as an intermediate product, has high use value and good application prospect, and has important significance for effectively removing nitrate in urban sewage, underground water and industrial wastewater.
(2) According to the preparation method, the copper-nickel alloy three-dimensional composite electrode loaded with copper hydroxide is prepared by adopting a one-step hydrothermal method for the first time, copper-nickel alloy can be prepared by a displacement reaction of copper and nickel, wherein urea is decomposed at a high temperature to generate an alkaline environment, which is favorable for copper hydroxide nanowires to closely grow on a nickel metal substrate, and direct addition of an alkaline solution can cause direct deposition of copper hydroxide, so that copper hydroxide cannot be closely connected with the nickel substrate, and simultaneously, the existence of ammonium fluoride can etch the surface of the nickel substrate to generate a higher specific surface area for loading copper and copper hydroxide nanowires.
(3) According to the invention, by optimizing the concentration of copper salt in the mixed solution, the electrode material with stronger reducing capability and better stability can be prepared, so that when the electrode material is used as a cathode for treating nitrate wastewater, nitrate can be reduced to ammonia nitrogen or nitrogen more quickly and thoroughly, because when the concentration of copper salt in the mixed solution is relatively low (for example, the concentration of copper salt in the mixed solution is 2.4 g/L), the loading amount of copper particles and copper hydroxide nanowires growing on the surface of the nickel metal substrate is lower, the active sites on the surface of the electrode are also reduced, the capability of the electrode for reducing nitrate is weakened, and meanwhile, when the concentration of copper salt in the mixed solution is relatively high (for example, the concentration of copper salt in the mixed solution is more than 9.6 g/L), excessive copper particles and copper hydroxide nanowires grow on the surface of the nickel metal substrate, so that the nickel active sites on the surface of the electrode are completely embedded, the copper particles are exposed to be less, the generation of active hydrogen is hindered, the accumulation of nitrite is caused, the nitrite and the competition with the nitrate for the active sites on the surface of the electrode is increased, and the capability of reducing the nitrate is reduced.
(4) In the present invention, the ammonia nitrogen generated can be oxidized to nitrogen by adding a chlorine salt and utilizing the hypochlorite having strong oxidizing property generated by the active chlorine generated by anodic oxidation of chlorine ions and water.
Drawings
In order to make the objects, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.
Fig. 1 is a scanning electron microscope image of a copper-nickel alloy three-dimensional composite electrode (A1) loaded with copper hydroxide prepared in example 1 of the present invention.
Fig. 2 is a graph showing the reduction effect of the copper-nickel alloy three-dimensional composite electrode (A1, A2, B1) loaded with copper hydroxide, the copper-nickel alloy electrode (B2) loaded with copper hydroxide by using the binder, the copper-nickel alloy electrode (B3), the copper electrode (B4) loaded with copper hydroxide, and the foam nickel electrode (B5) as the cathode in the example 1 of the present invention.
Fig. 3 is a graph showing the effect of reducing nitrate wastewater under different current densities by using the copper-nickel alloy three-dimensional composite electrode (A1) loaded with copper hydroxide as a cathode in example 2 of the present invention.
Fig. 4 is a graph showing the reduction effect of copper-nickel alloy three-dimensional composite electrode (A1) loaded with copper hydroxide as a cathode on nitrate wastewater with different concentrations in example 3 of the present invention.
Fig. 5 is a graph showing the effect of reducing nitrate wastewater by using the copper-nickel alloy three-dimensional composite electrode (A1) loaded with copper hydroxide as a cathode in example 4 of the present invention under the condition of adding chloride ions.
FIG. 6 is a graph showing the effect of the three-dimensional composite electrode (A1) of copper-nickel alloy loaded with copper hydroxide as a cathode for recycling nitrate wastewater in example 5 of the present invention.
FIG. 7 is a graph showing the effect of the binder-supported copper-nickel alloy electrode (B2) for recycling nitrate wastewater in example 5 of the present invention.
FIG. 8 is a graph showing the effect of the cyclic treatment of nitrate wastewater using a copper electrode carrying palladium and copper hydroxide as a cathode in example 5 of the present invention.
Detailed Description
The invention is further described below in connection with the drawings and the specific preferred embodiments, but the scope of protection of the invention is not limited thereby. The materials and instruments used in the examples below are all commercially available.
Example 1:
the method for treating nitrate wastewater by using copper-nickel alloy three-dimensional composite electrode loaded with copper hydroxide comprises the following steps of:
copper-nickel alloy three-dimensional composite electrodes (A1, A2 and B1) loaded with copper hydroxide, copper-nickel alloy electrode (B2) loaded with copper hydroxide by using a binder, copper-nickel alloy electrode (B3), copper electrode (B4) loaded with copper hydroxide and foam nickel electrode (B5) are respectively used as cathodes, ruthenium iridium titanium electrode is used as an anode, and the electrodes are placed in an electrochemical reactor, 100mL of nitrate wastewater containing sodium sulfate is added, the concentration of the nitrate wastewater is 100mg/L in terms of nitrate nitrogen, the concentration of the sodium sulfate is 0.05mol/L, and the current density is 12mA/cm 2 Is constant in (2)And (3) carrying out electrochemical reduction reaction for 1.5h under the flow condition to finish the treatment of nitrate wastewater.
In the embodiment, the copper-nickel alloy three-dimensional composite electrode (A1) loaded with copper hydroxide comprises a nickel metal substrate, copper particles and copper hydroxide nanowires are grown on the nickel metal substrate, wherein nickel is foamed on the nickel metal substrate, and the length, the height and the width of the foamed nickel are 4cm multiplied by 3cm multiplied by 0.1cm.
In this embodiment, the preparation method of the copper-nickel alloy three-dimensional composite electrode (A1) loaded with copper hydroxide includes the following steps:
pretreating 4cm multiplied by 3cm multiplied by 0.1cm foam nickel sequentially by ethanol, 1mol/L hydrochloric acid solution and ultrapure water, removing surface oxides and impurities by cleaning, soaking the pretreated foam nickel in 100mL of aqueous solution containing 0.48g of copper nitrate trihydrate, 0.15g of ammonium fluoride and 0.6g of urea, uniformly mixing, then placing the obtained mixed solution in a high-pressure reaction kettle, heating to 105 ℃ for 4 hours, and obtaining the copper-nickel alloy three-dimensional composite electrode loaded with copper hydroxide, namely the three-dimensional composite electrode-0.48.
In this embodiment, the preparation method of the copper-nickel alloy three-dimensional composite electrode (A2) loaded with copper hydroxide is basically the same as the preparation method of the copper-nickel alloy three-dimensional composite electrode (A1) loaded with copper hydroxide, and the difference is that: the aqueous solution contained 0.96g of copper nitrate trihydrate.
In this embodiment, the preparation method of the copper-nickel alloy three-dimensional composite electrode (B1) loaded with copper hydroxide is basically the same as the preparation method of the copper-nickel alloy three-dimensional composite electrode (A1) loaded with copper hydroxide, and the difference is that: the aqueous solution contained 0.24g of copper nitrate trihydrate.
In this embodiment, the preparation method of the copper-nickel alloy electrode (B2) using the binder to load copper hydroxide includes the following steps:
pretreating foam nickel of 4cm multiplied by 3cm multiplied by 0.1cm respectively by ethanol, 1mol/L hydrochloric acid solution and ultrapure water, removing surface oxides and impurities by cleaning, soaking the pretreated foam nickel in 100mL of aqueous solution containing 0.48g of copper nitrate trihydrate, and heating the mixed solution in a high-pressure reaction kettle to 105 ℃ for reaction for 4 hours to obtain the copper-nickel alloy electrode. An aqueous solution containing 0.48g of copper nitrate trihydrate, 0.15g of ammonium fluoride and 0.6g of urea was placed in a high-pressure reaction kettle, heated to 105 ℃ for reaction for 4 hours, washed with water and dried to obtain copper hydroxide powder. Dissolving the prepared copper hydroxide powder, acetylene black and polyvinylidene fluoride in N-methyl-2-pyrrolidone, adhering the mixture to the prepared copper-nickel alloy electrode, and drying the mixture at 60 ℃ for 8 hours to obtain the copper-nickel alloy electrode with the binder loaded with copper hydroxide, wherein the copper-nickel alloy electrode is denoted as B2.
In this embodiment, the preparation method of the copper-nickel alloy electrode (B3) includes the following steps:
the foam nickel of 4cm multiplied by 3cm multiplied by 0.1cm is respectively pretreated by ethanol, 1mol/L hydrochloric acid solution and ultrapure water, surface oxides and impurities are removed by cleaning, the pretreated foam nickel is soaked in 100mL of aqueous solution containing 0.48g of copper nitrate trihydrate, and the mixed solution is placed in a high-pressure reaction kettle to be heated to 105 ℃ for reaction for 4 hours, so that a copper-nickel alloy electrode is obtained and is marked as B3.
In this embodiment, the preparation method of the copper electrode (B4) loaded with copper hydroxide includes the following steps:
4cm×3cm×0.1cm of copper foam was pretreated with ethanol, 1mol/L hydrochloric acid solution and ultrapure water, surface oxides and impurities were removed by washing, and then the pretreated nickel foam was immersed in 100mL of an aqueous solution containing 0.48g of copper nitrate trihydrate, 0.15g of ammonium fluoride and 0.6g of urea, and the mixed solution was heated to 105 ℃ in a high-pressure reaction vessel for reaction for 4 hours to obtain a copper electrode carrying copper hydroxide, denoted as B4.
In this embodiment, the preparation method of the foam nickel electrode (B5) includes the following steps:
the foamed nickel of 4 cm.times.3 cm.times.0.1 cm was pretreated with ethanol, 1mol/L hydrochloric acid solution and ultrapure water, respectively, and surface oxides and impurities were removed by washing to obtain a foamed nickel electrode, designated as B5.
Fig. 1 is a scanning electron microscope image of a copper-nickel alloy three-dimensional composite electrode (A1) loaded with copper hydroxide prepared in example 1 of the present invention. As can be seen from fig. 1, in the copper-nickel alloy three-dimensional composite electrode loaded with copper hydroxide prepared by the method, copper particles and copper hydroxide nanowires are uniformly loaded on foam nickel.
Fig. 2 is a graph showing the reduction effect of the copper-nickel alloy three-dimensional composite electrode (A1, A2, B1) loaded with copper hydroxide, the copper-nickel alloy electrode (B2) loaded with copper hydroxide by using the binder, the copper-nickel alloy electrode (B3), the copper electrode (B4) loaded with copper hydroxide, and the foam nickel electrode (B5) as the cathode in the example 1 of the present invention. As can be seen from fig. 2, when the three-dimensional composite copper-nickel alloy electrodes (A1, A2, and B1) carrying copper hydroxide, the copper-nickel alloy electrode (B2) carrying copper hydroxide as binder, the copper-nickel alloy electrode (B3), the copper electrode (B4) carrying copper hydroxide, and the foam nickel electrode (B5) are used as cathodes, respectively, the removal rate of nitrate (calculated as nitrate nitrogen) in wastewater is 96.28%, 88.22%, 60.2%, 76.9%, 56.76%, 51.34%, and 3.82%, respectively, and therefore, when the cathode is used for treating nitrate wastewater, nitrate can be reduced to ammonia nitrogen or nitrogen more rapidly and thoroughly by optimizing the concentration of copper salt in the mixed solution, this is because when the concentration of copper salt in the mixed solution is relatively low (e.g., the concentration of copper salt in the mixed solution is 2.4 g/L), the loading amount of copper particles and copper hydroxide nanowires grown on the surface of the nickel metal substrate is low, which causes the active sites on the surface of the electrode to be reduced, thereby weakening the capability of reducing nitrate, and at the same time, when the concentration of copper salt in the mixed solution is relatively high (e.g., the concentration of copper salt in the mixed solution exceeds 9.6 g/L), excessive copper particles and copper hydroxide nanowires grow on the surface of the nickel metal substrate, so that the nickel active sites on the surface of the electrode are completely embedded, are exposed to a small extent, thereby obstructing the generation of active hydrogen, causing the accumulation of nitrite, and further increasing the competition of nitrite and nitrate for the active sites on the surface of the electrode, eventually reducing the electrode's ability to reduce nitrate.
Example 2:
the method for treating nitrate wastewater by using copper-nickel alloy three-dimensional composite electrode loaded with copper hydroxide comprises the following steps of:
the copper-nickel alloy three-dimensional composite electrode (A1) loaded with copper hydroxide prepared in example 1 is taken as a cathode, a ruthenium iridium titanium electrode is taken as an anode, and is placed in an electrochemical reactor, 100mL of nitrate wastewater containing sodium sulfate is added, the concentration of the nitrate wastewater is 100mg/L calculated by nitrate nitrogen, the concentration of sodium sulfate is 0.05mol/L, and the current densities are 6mA/cm respectively 2 、9mA/cm 2 、12mA/cm 2 、15mA/cm 2 And (3) carrying out electrochemical reduction reaction for 1.5h under the constant-current condition to finish the treatment of nitrate wastewater.
Fig. 3 is a graph showing the effect of reducing nitrate wastewater under different current densities by using the copper-nickel alloy three-dimensional composite electrode (A1) loaded with copper hydroxide as a cathode in example 2 of the present invention. As can be seen from FIG. 3, when the current density is from 6mA/cm 2 Increase to 15mA/cm 2 When the electrochemical reduction treatment is carried out for 1.5 hours, the removal efficiency of nitrate nitrogen is improved from 85.40% to 98.92%, and the yield of nitrite nitrogen is reduced from 41mg/L to 6.9mg/L, which shows that good nitrate removal effect can be achieved under the condition of low current density, and meanwhile, the removal of nitrite as an intermediate product is facilitated due to the high current density.
Example 3:
the method for treating nitrate wastewater by using copper-nickel alloy three-dimensional composite electrode loaded with copper hydroxide comprises the following steps of:
the copper-nickel alloy three-dimensional composite electrode (A1) loaded with copper hydroxide prepared in example 1 is taken as a cathode, a ruthenium iridium titanium electrode is taken as an anode, the copper-nickel alloy three-dimensional composite electrode is placed in an electrochemical reactor, 100mL of nitrate wastewater containing sodium sulfate with different concentrations are added, the nitrate wastewater with different concentrations is sequentially 100mg/L, 200mg/L and 400mg/L in terms of nitrate nitrogen, the concentration of sodium sulfate is 0.05mol/L, and the current density is 12mA/cm 2 Is carried out under constant current conditions of (2)And (3) performing electrochemical reduction reaction for 1.5 hours to finish the treatment of nitrate wastewater.
Fig. 4 is a graph showing the reduction effect of copper-nickel alloy three-dimensional composite electrode (A1) loaded with copper hydroxide as a cathode on nitrate wastewater with different concentrations in example 3 of the present invention. As can be seen from FIG. 4, when the initial nitrate nitrogen concentration is increased from 100mg/L to 400mg/L, the nitrate nitrogen removal rate is reduced from 96.28% to 40.3%, but the actual nitrate nitrogen removal amount is increased from 96.28mg/L to 161.2mg/L, which shows that the copper-nickel alloy three-dimensional composite electrode loaded with copper hydroxide can also play a better role in reducing under a higher initial nitrate concentration.
Example 4:
the method for treating nitrate wastewater by using copper-nickel alloy three-dimensional composite electrode loaded with copper hydroxide comprises the following steps of:
the copper-nickel alloy three-dimensional composite electrode (A1) loaded with copper hydroxide prepared in example 1 is taken as a cathode, a ruthenium iridium titanium electrode is taken as an anode, and is placed in an electrochemical reactor, 100mL of nitrate wastewater containing sodium sulfate and sodium chloride is added, the nitrate wastewater has a concentration of 100mg/L calculated by nitrate nitrogen, the concentration of sodium sulfate is 0.05mol/L, the concentration of sodium chloride is 0.5g/L, and the current density is 12mA/cm 2 And (3) carrying out electrochemical reduction reaction for 3 hours under the constant-current condition to finish the treatment of nitrate wastewater.
Fig. 5 is a graph showing the effect of reducing nitrate wastewater by using the copper-nickel alloy three-dimensional composite electrode (A1) loaded with copper hydroxide as a cathode in example 4 of the present invention under the condition of adding chloride ions. As can be seen from FIG. 5, when the initial sodium chloride concentration is 0.5g/L, the nitrate nitrogen removal efficiency is slightly reduced to 95.42%, but the nitrogen selectivity is improved to 91.32%, which shows that the copper-nickel alloy three-dimensional composite electrode loaded with copper hydroxide can achieve higher nitrogen selectivity under the condition of adding chloride ions. Meanwhile, as can be seen from the results in fig. 3 and 5, the selectivity to nitrogen can be higher than 50% without adding chloride ions, but the selectivity to nitrogen after adding chloride ions is higher than 95%.
Example 5:
the method for treating nitrate wastewater by using copper-nickel alloy three-dimensional composite electrode loaded with copper hydroxide is to repeatedly perform electrochemical reduction treatment on nitrate wastewater by using the copper-nickel alloy three-dimensional composite electrode loaded with copper hydroxide as a cathode, and comprises the following steps:
(1) The copper-nickel alloy three-dimensional composite electrode (A1) carrying copper hydroxide prepared in example 1 was used as a cathode, a ruthenium iridium titanium electrode (commercially available) was used as an anode, and placed in an electrochemical reactor, 100mL of nitrate wastewater containing sodium sulfate was added, the concentration of the nitrate wastewater was 100mg/L in terms of nitrate nitrogen, the concentration of sodium sulfate was 0.05mol/L, and the current density was 12mA/cm 2 And (3) carrying out electrochemical reduction reaction for 1.5h under the constant-current condition to finish the treatment of nitrate wastewater.
(2) After the step (1) is finished, the copper-nickel alloy three-dimensional composite electrode (A1) loaded with copper hydroxide is continuously used for treating nitrate wastewater containing sodium sulfate, and the treatment conditions are the same as those of the step (1) and are repeated for 20 times.
In this example, the effect of the binder-supported copper-nickel alloy electrode (B2) and the palladium-and copper-hydroxide-supported copper electrode on the cyclic treatment of nitrate wastewater was examined, and the conditions were the same except for the cathode material.
In this embodiment, the method for preparing the copper electrode loaded by palladium and copper hydroxide includes the following steps:
soaking 4cm×3cm×0.1cm copper foam in a solution containing 2.5mol/L sodium hydroxide and 0.125mol/L (NH) 4 ) 2 S 2 O 8 Soaking for 4min to prepare a copper electrode loaded with copper hydroxide nanowires, then placing the copper electrode loaded with copper hydroxide nanowires in a palladium chloride solution with the concentration of 2mmol/L for electrodeposition, and depositing palladium on the surface of the copper electrode loaded with copper hydroxide nanowires to obtain the copper electrode loaded with palladium and copper hydroxide.
FIG. 6 is a graph showing the effect of the three-dimensional composite electrode (A1) of copper-nickel alloy loaded with copper hydroxide as a cathode for recycling nitrate wastewater in example 5 of the present invention. From fig. 6, after the copper-nickel alloy three-dimensional composite electrode (A1) loaded with copper hydroxide is circulated for 20 times, the removal rate of nitrate is reduced from 98.4% to 93.45%, which shows that the electrode has good stability, can be repeatedly used for treating nitrate wastewater for many times, and is beneficial to reducing the cost.
FIG. 7 is a graph showing the effect of the binder-supported copper-nickel alloy electrode (B2) for recycling nitrate wastewater in example 5 of the present invention. As can be seen from fig. 7, after 5 cycles, the removal rate of nitrate by the binder-supported copper-nickel alloy electrode (B2) was reduced from 76.9% to 50.76%, which may be caused by the falling-off of the binder on the electrode surface.
FIG. 8 is a graph showing the effect of the cyclic treatment of nitrate wastewater using a copper electrode carrying palladium and copper hydroxide as a cathode in example 5 of the present invention. As can be seen from fig. 8, after 4 cycles, the removal rate of nitrate by the copper electrode loaded with palladium and copper hydroxide was reduced from 98.2% to 92.5%, probably due to the shedding of electrodeposited palladium metal on the electrode surface.
From the above results, it is clear that in the present invention, when a copper-nickel alloy three-dimensional composite electrode carrying copper hydroxide is used as a cathode, cu and Cu on the electrode surface can be used in a reactor 2 The O-mediated electron transfer function can quickly reduce nitrate in water into nitrite, ammonia nitrogen, nitrogen and other products, meanwhile, the copper hydroxide nanowire is loaded, so that the electrode has higher specific surface area and more positive charges, the active site on the surface of the electrode and the adsorption function on nitrate and nitrite can be increased, reduction of nitrate and nitrite is facilitated, meanwhile, the nickel metal substrate serving as a good hydrogen evolution material can generate a large amount of active hydrogen in electrochemical reduction of nitrate, and therefore, exposure of nickel substrate sites in the three-dimensional composite electrode can generate a large amount of active hydrogen, thereby promoting reduction of nitrite. Compared with the conventional cathode material, the copper hydroxide-loaded cathode material used in the inventionThe copper-nickel alloy three-dimensional composite electrode has two ways of reducing nitrate, namely, the nitrate can be reduced through electron transfer on the surface of the cathode, and the nitrate can be reduced through active hydrogen generated by the cathode, and the copper-nickel alloy three-dimensional composite electrode has the advantages of high electron transfer rate, strong nitrate and nitrite adsorption capability, strong active hydrogen production capability and the like, so that the electrochemical reduction of the nitrate is facilitated; more importantly, the copper particles and the copper hydroxide nanowires can stably grow on the surface of the nickel metal substrate, so that the electrode has excellent stability, can be repeatedly used for treating nitrate wastewater, can remarkably reduce the treatment cost, and can not bring secondary pollution. Therefore, the method for treating the nitrate wastewater by using the copper-nickel alloy three-dimensional composite electrode loaded with copper hydroxide has the advantages of low treatment cost, high treatment efficiency, good removal effect, environmental protection and the like, can be widely adopted, can effectively remove nitrate in water, can realize the efficient treatment of the nitrate wastewater, has high removal rate of nitrite as an intermediate product, has high use value and good application prospect, and has important significance for effectively removing nitrate in urban sewage, underground water and industrial wastewater.
The above examples are only preferred embodiments of the present invention, and the scope of the present invention is not limited to the above examples. All technical schemes belonging to the concept of the invention belong to the protection scope of the invention. It should be noted that modifications and adaptations to the present invention may occur to one skilled in the art without departing from the principles of the present invention and are intended to be within the scope of the present invention.
Claims (10)
1. A method for treating nitrate wastewater by using copper-nickel alloy three-dimensional composite electrode loaded with copper hydroxide is characterized in that the method uses the copper-nickel alloy three-dimensional composite electrode loaded with copper hydroxide as a cathode to carry out electrochemical reduction treatment on nitrate wastewater; the copper-nickel alloy three-dimensional composite electrode loaded with copper hydroxide comprises a nickel metal substrate, wherein copper particles and copper hydroxide nanowires are grown on the nickel metal substrate;
the preparation method of the copper-nickel alloy three-dimensional composite electrode loaded with copper hydroxide comprises the following steps:
s1, mixing a nickel metal substrate with a mixed solution of copper salt, ammonium fluoride and urea to obtain a mixed solution;
s2, carrying out hydrothermal reaction on the mixed solution obtained in the step S1 to obtain the copper-nickel alloy three-dimensional composite electrode loaded with copper hydroxide.
2. The method of claim 1, wherein the nickel metal substrate is any one of nickel plate, nickel mesh, and nickel foam.
3. The method according to claim 2, characterized in that in step S1 the concentration of copper salt in the mixed solution is greater than 2.4g/L.
4. A method according to claim 3, characterized in that in step S1 the concentration of copper salt in the mixed solution is 3 g/L-9.6 g/L.
5. The method according to claim 4, wherein in step S1, the concentration of copper salt in the mixed solution is 4g/L to 8g/L.
6. The method of claim 5, wherein in step S1, the nickel metal base further comprises the following treatments prior to use: sequentially adopting ethanol, hydrochloric acid solution and water for cleaning treatment to remove surface oxides and impurities; the concentration of the hydrochloric acid solution is 0.5 mol/L-1 mol/L; the concentration of ammonium fluoride in the mixed solution is 1.5 g/L-2 g/L, and the concentration of urea is 6g g/L-8 g/L; the mixed solution of copper salt, ammonium fluoride and urea is prepared by dissolving copper salt, ammonium fluoride and urea into water; the copper salt is copper nitrate and/or copper chloride;
in step S2, the hydrothermal reaction is performed in a high-pressure reaction kettle; the temperature of the hydrothermal reaction is 105-150 ℃; the hydrothermal reaction time is 4-6 h.
7. The method according to any one of claims 1 to 6, further comprising, during the electrochemical reduction treatment: adding electrolyte into nitrate wastewater to ensure that the concentration of the electrolyte in the system is 0.05mol/L to 0.1mol/L; the electrolyte is sodium sulfate.
8. The method according to claim 7, wherein during the electrochemical reduction process, further comprising: adding chloride into the nitrate wastewater to ensure that the concentration of the chloride in the system is 0.5g/L; the chloride salt is sodium chloride.
9. The method according to claim 8, wherein the ruthenium iridium titanium electrode is used as an anode in the electrochemical reduction treatment process;
the electrochemical reduction treatment is performed under a constant current condition; the current density is controlled to be 6mA/cm in the electrochemical reduction treatment process 2 ～20mA/cm 2 The method comprises the steps of carrying out a first treatment on the surface of the The electrochemical reduction treatment time is 1.5-3 hours;
the concentration of the nitrate wastewater is less than or equal to 100mg/L based on nitrate nitrogen.
10. The method according to any one of claims 1 to 6, further comprising, after completion of the electrochemical reduction treatment, the following treatments: and (3) repeatedly performing electrochemical reduction treatment on the nitrate wastewater by taking the copper-nickel alloy three-dimensional composite electrode loaded with copper hydroxide as a cathode, wherein the repetition times are 1-20 times.
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