CN115178287A - Preparation method of nitrogen-doped flower-shaped cobalt-manganese composite oxide and method for degrading antibiotic wastewater - Google Patents
Preparation method of nitrogen-doped flower-shaped cobalt-manganese composite oxide and method for degrading antibiotic wastewater Download PDFInfo
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- CN115178287A CN115178287A CN202210839798.3A CN202210839798A CN115178287A CN 115178287 A CN115178287 A CN 115178287A CN 202210839798 A CN202210839798 A CN 202210839798A CN 115178287 A CN115178287 A CN 115178287A
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- hydrotalcite
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- MZZUATUOLXMCEY-UHFFFAOYSA-N cobalt manganese Chemical compound [Mn].[Co] MZZUATUOLXMCEY-UHFFFAOYSA-N 0.000 title claims abstract description 120
- 239000002131 composite material Substances 0.000 title claims abstract description 58
- 239000002351 wastewater Substances 0.000 title claims abstract description 40
- 238000000034 method Methods 0.000 title claims abstract description 39
- 230000003115 biocidal effect Effects 0.000 title claims abstract description 34
- 230000000593 degrading effect Effects 0.000 title claims abstract description 14
- 238000002360 preparation method Methods 0.000 title claims abstract description 10
- GDVKFRBCXAPAQJ-UHFFFAOYSA-A dialuminum;hexamagnesium;carbonate;hexadecahydroxide Chemical compound [OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Al+3].[Al+3].[O-]C([O-])=O GDVKFRBCXAPAQJ-UHFFFAOYSA-A 0.000 claims abstract description 78
- 229910001701 hydrotalcite Inorganic materials 0.000 claims abstract description 78
- 229960001545 hydrotalcite Drugs 0.000 claims abstract description 78
- 238000010438 heat treatment Methods 0.000 claims abstract description 50
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 37
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 37
- 239000012265 solid product Substances 0.000 claims abstract description 34
- 150000001868 cobalt Chemical class 0.000 claims abstract description 28
- 238000001035 drying Methods 0.000 claims abstract description 28
- 238000001027 hydrothermal synthesis Methods 0.000 claims abstract description 28
- 238000005406 washing Methods 0.000 claims abstract description 28
- 150000002696 manganese Chemical class 0.000 claims abstract description 26
- 230000015556 catabolic process Effects 0.000 claims abstract description 24
- 238000006731 degradation reaction Methods 0.000 claims abstract description 24
- WQZGKKKJIJFFOK-GASJEMHNSA-N Glucose Natural products OC[C@H]1OC(O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-GASJEMHNSA-N 0.000 claims abstract description 23
- 239000008103 glucose Substances 0.000 claims abstract description 23
- JRKICGRDRMAZLK-UHFFFAOYSA-L peroxydisulfate Chemical compound [O-]S(=O)(=O)OOS([O-])(=O)=O JRKICGRDRMAZLK-UHFFFAOYSA-L 0.000 claims abstract description 19
- 150000005846 sugar alcohols Polymers 0.000 claims abstract description 19
- 238000003756 stirring Methods 0.000 claims abstract description 18
- 150000001412 amines Chemical class 0.000 claims abstract description 16
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 16
- 239000012299 nitrogen atmosphere Substances 0.000 claims abstract description 12
- 239000000047 product Substances 0.000 claims abstract description 12
- 239000012153 distilled water Substances 0.000 claims abstract description 11
- 238000002156 mixing Methods 0.000 claims abstract description 9
- 239000011572 manganese Substances 0.000 claims description 22
- 239000012425 OXONE® Substances 0.000 claims description 13
- HJKYXKSLRZKNSI-UHFFFAOYSA-I pentapotassium;hydrogen sulfate;oxido sulfate;sulfuric acid Chemical compound [K+].[K+].[K+].[K+].[K+].OS([O-])(=O)=O.[O-]S([O-])(=O)=O.OS(=O)(=O)O[O-].OS(=O)(=O)O[O-] HJKYXKSLRZKNSI-UHFFFAOYSA-I 0.000 claims description 13
- 230000008569 process Effects 0.000 claims description 10
- CHQMHPLRPQMAMX-UHFFFAOYSA-L sodium persulfate Substances [Na+].[Na+].[O-]S(=O)(=O)OOS([O-])(=O)=O CHQMHPLRPQMAMX-UHFFFAOYSA-L 0.000 claims description 9
- HZAXFHJVJLSVMW-UHFFFAOYSA-N 2-Aminoethan-1-ol Chemical compound NCCO HZAXFHJVJLSVMW-UHFFFAOYSA-N 0.000 claims description 8
- GSEJCLTVZPLZKY-UHFFFAOYSA-N Triethanolamine Chemical compound OCCN(CCO)CCO GSEJCLTVZPLZKY-UHFFFAOYSA-N 0.000 claims description 8
- 229910021645 metal ion Inorganic materials 0.000 claims description 8
- LCPVQAHEFVXVKT-UHFFFAOYSA-N 2-(2,4-difluorophenoxy)pyridin-3-amine Chemical compound NC1=CC=CN=C1OC1=CC=C(F)C=C1F LCPVQAHEFVXVKT-UHFFFAOYSA-N 0.000 claims description 6
- ZBCBWPMODOFKDW-UHFFFAOYSA-N diethanolamine Chemical compound OCCNCCO ZBCBWPMODOFKDW-UHFFFAOYSA-N 0.000 claims description 5
- USHAGKDGDHPEEY-UHFFFAOYSA-L potassium persulfate Chemical compound [K+].[K+].[O-]S(=O)(=O)OOS([O-])(=O)=O USHAGKDGDHPEEY-UHFFFAOYSA-L 0.000 claims description 3
- 230000003197 catalytic effect Effects 0.000 abstract description 15
- 230000000694 effects Effects 0.000 abstract description 14
- 239000002957 persistent organic pollutant Substances 0.000 abstract description 7
- 230000003213 activating effect Effects 0.000 abstract description 6
- GSDSWSVVBLHKDQ-JTQLQIEISA-N Levofloxacin Chemical compound C([C@@H](N1C2=C(C(C(C(O)=O)=C1)=O)C=C1F)C)OC2=C1N1CCN(C)CC1 GSDSWSVVBLHKDQ-JTQLQIEISA-N 0.000 description 42
- 229960003376 levofloxacin Drugs 0.000 description 42
- 239000000243 solution Substances 0.000 description 37
- 238000006243 chemical reaction Methods 0.000 description 30
- 239000003054 catalyst Substances 0.000 description 19
- 239000003795 chemical substances by application Substances 0.000 description 16
- 239000011949 solid catalyst Substances 0.000 description 12
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 10
- 238000010791 quenching Methods 0.000 description 10
- 230000000171 quenching effect Effects 0.000 description 10
- 238000005070 sampling Methods 0.000 description 10
- 238000002798 spectrophotometry method Methods 0.000 description 10
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- 239000013078 crystal Substances 0.000 description 7
- 229910052751 metal Inorganic materials 0.000 description 7
- 239000002994 raw material Substances 0.000 description 6
- 238000006555 catalytic reaction Methods 0.000 description 5
- 229910001429 cobalt ion Inorganic materials 0.000 description 5
- XLJKHNWPARRRJB-UHFFFAOYSA-N cobalt(2+) Chemical compound [Co+2] XLJKHNWPARRRJB-UHFFFAOYSA-N 0.000 description 5
- 230000001976 improved effect Effects 0.000 description 5
- 229910001437 manganese ion Inorganic materials 0.000 description 5
- 239000002184 metal Substances 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- 229910052757 nitrogen Inorganic materials 0.000 description 5
- 239000012716 precipitator Substances 0.000 description 5
- -1 sulfate radicals Chemical class 0.000 description 5
- 229910044991 metal oxide Inorganic materials 0.000 description 4
- 150000004706 metal oxides Chemical class 0.000 description 4
- 230000006911 nucleation Effects 0.000 description 4
- 238000010899 nucleation Methods 0.000 description 4
- 230000010355 oscillation Effects 0.000 description 4
- FHHJDRFHHWUPDG-UHFFFAOYSA-L peroxysulfate(2-) Chemical compound [O-]OS([O-])(=O)=O FHHJDRFHHWUPDG-UHFFFAOYSA-L 0.000 description 4
- 230000008901 benefit Effects 0.000 description 3
- 150000001768 cations Chemical class 0.000 description 3
- 239000003344 environmental pollutant Substances 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 231100000719 pollutant Toxicity 0.000 description 3
- 239000002243 precursor Substances 0.000 description 3
- 238000004064 recycling Methods 0.000 description 3
- QAOWNCQODCNURD-UHFFFAOYSA-N sulfuric acid Substances OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 3
- 229910000314 transition metal oxide Inorganic materials 0.000 description 3
- 230000004913 activation Effects 0.000 description 2
- 150000001450 anions Chemical class 0.000 description 2
- 238000003763 carbonization Methods 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 238000010668 complexation reaction Methods 0.000 description 2
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- 229910052760 oxygen Inorganic materials 0.000 description 2
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- HDMGAZBPFLDBCX-UHFFFAOYSA-M potassium;sulfooxy sulfate Chemical compound [K+].OS(=O)(=O)OOS([O-])(=O)=O HDMGAZBPFLDBCX-UHFFFAOYSA-M 0.000 description 2
- 230000027756 respiratory electron transport chain Effects 0.000 description 2
- 239000012266 salt solution Substances 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 description 1
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- 238000009303 advanced oxidation process reaction Methods 0.000 description 1
- 239000012670 alkaline solution Substances 0.000 description 1
- 239000003242 anti bacterial agent Substances 0.000 description 1
- 229940088710 antibiotic agent Drugs 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 239000004202 carbamide Substances 0.000 description 1
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- 239000011943 nanocatalyst Substances 0.000 description 1
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- 229910000510 noble metal Inorganic materials 0.000 description 1
- 229920005862 polyol Polymers 0.000 description 1
- 150000003077 polyols Chemical class 0.000 description 1
- 238000004321 preservation Methods 0.000 description 1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
- B01J27/24—Nitrogen compounds
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J35/00—Catalysts, in general, characterised by their form or physical properties
- B01J35/30—Catalysts, in general, characterised by their form or physical properties characterised by their physical properties
- B01J35/33—Electric or magnetic properties
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/08—Heat treatment
- B01J37/082—Decomposition and pyrolysis
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/08—Heat treatment
- B01J37/10—Heat treatment in the presence of water, e.g. steam
-
- 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
- C02F1/72—Treatment of water, waste water, or sewage by oxidation
- C02F1/722—Oxidation by peroxides
-
- 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
- C02F1/72—Treatment of water, waste water, or sewage by oxidation
- C02F1/725—Treatment of water, waste water, or sewage by oxidation by catalytic oxidation
-
- 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
- C02F2101/30—Organic compounds
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2305/00—Use of specific compounds during water treatment
- C02F2305/02—Specific form of oxidant
- C02F2305/023—Reactive oxygen species, singlet oxygen, OH radical
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- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Environmental & Geological Engineering (AREA)
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Abstract
The invention discloses a preparation method of a nitrogen-doped flower-shaped cobalt-manganese composite oxide and a method for degrading antibiotic wastewater, wherein the preparation method of the nitrogen-doped flower-shaped cobalt-manganese composite oxide comprises the following steps: adding cobalt salt, manganese salt and polyalcohol amine into distilled water in sequence, stirring and mixing, then carrying out hydrothermal reaction, separating out a solid product, washing and drying to obtain cobalt-manganese hydrotalcite; adding cobalt-manganese hydrotalcite into a glucose solution, carrying out hydrothermal reaction, separating out a solid product, washing and drying to obtain cobalt-manganese hydrotalcite with a carbon-modified surface; and heating and roasting the cobalt-manganese hydrotalcite with the surface carbon modified in the nitrogen atmosphere, and washing and drying a roasted product to obtain the cobalt-manganese composite oxide. The nitrogen-doped flower-shaped cobalt-manganese composite oxide prepared by the invention has a flower-shaped multi-level regular structure and higher intrinsic conductivity and intrinsic activity, is used for catalytically activating persulfate to degrade waste water, and can effectively improve the catalytic degradation activity and degradation rate of organic pollutants in the waste water.
Description
Technical Field
The invention relates to the technical field of sewage treatment, in particular to a preparation method of a nitrogen-doped flower-shaped cobalt-manganese composite oxide and a method for degrading antibiotic wastewater.
Background
Nowadays, water pollution caused by abuse of antibiotics has become a serious environmental problem seriously threatening human health and social development, and the development of effective degradation technology is urgently needed. In recent years, advanced oxidation processes based on sulfate radicals are receiving more and more attention, and active oxygen with strong oxidation capacity can be generated through the catalytic activation of Persulfate (PS) or Peroxymonosulfate (PMS), so that various organic pollutants in water can be effectively degraded or mineralized.
Among them, cobalt-manganese composite oxides have received much attention because of their strong electron transfer ability due to the bimetallic reduction cycle, and thus exhibit excellent PMS activation ability, and it is important to further improve their catalytic activity, reduce the reaction barrier, and improve the intrinsic conductivity and active site density.
Disclosure of Invention
The invention mainly aims to provide a preparation method of a nitrogen-doped flower-shaped cobalt-manganese composite oxide and a method for degrading antibiotic wastewater, and aims to improve the catalytic activity of the cobalt-manganese composite oxide.
In order to achieve the purpose, the invention provides a preparation method of a nitrogen-doped flower-shaped cobalt-manganese composite oxide, which comprises the following steps:
adding cobalt salt, manganese salt and polyalcohol amine into distilled water in sequence, stirring and mixing, heating to 80-160 ℃, carrying out hydrothermal reaction for 6-20 h, separating out a solid product, washing and drying to obtain nitrogen-doped flower-shaped cobalt-manganese hydrotalcite;
adding the cobalt-manganese hydrotalcite into a glucose solution, heating to 120-200 ℃ to perform hydrothermal reaction for 6-12 h, separating out a solid product, washing and drying to obtain the cobalt-manganese hydrotalcite with the carbon modified surface;
heating the cobalt-manganese hydrotalcite with the carbon modified surface to 500-600 ℃ in a nitrogen atmosphere, preserving the heat for 0.5-2 h, washing and drying a roasted product to obtain the nitrogen-doped flower-shaped cobalt-manganese composite oxide.
Optionally, the cobalt salt comprises CoCl 2 、Co(NO 3 ) 2 And Co (CH) 3 COO) 2 At least one of (1).
Optionally, the manganese salt comprises MnCl 2 、Mn(NO 3 ) 2 And MnSO 4 At least one of (a).
Optionally, the polyalcohol amine comprises at least one of triethanolamine, ethanolamine, and diethanolamine.
Optionally, adding cobalt salt, manganese salt and polyalcohol amine into distilled water in sequence, stirring and mixing, heating to 80-160 ℃ for hydrothermal reaction for 6-20 h, separating out a solid product, washing and drying to obtain the nitrogen-doped flower-shaped cobalt-manganese hydrotalcite:
the molar ratio of the cobalt salt to the manganese salt is 1;
the ratio of the total amount of metal ions such as cobalt salt and manganese salt to the amount of the polyhydric alcohol is 1;
the total molar concentration of the metal ions such as cobalt salt and manganese salt is 0.01-0.1M.
Optionally, adding the cobalt-manganese hydrotalcite into a glucose solution, heating to 120-200 ℃ to perform hydrothermal reaction for 6-12 h, separating out a solid product, washing and drying to obtain the cobalt-manganese hydrotalcite with the carbon-modified surface, wherein the step of:
the concentration of the glucose solution is 0.005-0.02M;
adding 2-5L of the glucose solution into every 2g of the cobalt-manganese hydrotalcite.
Optionally, in a nitrogen atmosphere, heating the cobalt-manganese hydrotalcite with the carbon-modified surface to 500-600 ℃, then preserving heat for 0.5-2 h, washing and drying a roasted product to obtain the nitrogen-doped flower-shaped cobalt-manganese composite oxide, wherein the nitrogen-doped flower-shaped cobalt-manganese composite oxide comprises the following steps:
the heating rate is 1-5 ℃/min in the process of heating to 500-600 ℃.
Further, the invention also provides a method for degrading antibiotic wastewater, which comprises the following steps:
adding nitrogen-doped flower-shaped cobalt-manganese composite oxide into the antibiotic wastewater to be treated, then adding persulfate, stirring, heating to 30-50 ℃, reacting for 0.5-2 h, and finishing degradation treatment on the antibiotic wastewater;
the nitrogen-doped flower-shaped cobalt-manganese composite oxide is prepared by the preparation method of the nitrogen-doped flower-shaped cobalt-manganese composite oxide.
Optionally, the persulfate comprises at least one of sodium persulfate, potassium persulfate, sodium monopersulfate, potassium monopersulfate, and potassium hydrogen persulfate.
Optionally, 0.1-1 g of the nitrogen-doped flower-shaped cobalt-manganese composite oxide and 0.2-0.6 g of the persulfate are correspondingly added into each liter of antibiotic wastewater.
According to the technical scheme provided by the invention, cobalt salt and manganese salt are used as precursors, polyalcohol amine is used as a nitrogen source, a precipitator and a structure directing agent, the nitrogen-doped flower-shaped cobalt-manganese hydrotalcite is prepared by a hydrothermal method, then the nitrogen-doped flower-shaped cobalt-manganese hydrotalcite is added into a glucose solution, carbon-coated nitrogen-doped flower-shaped cobalt-manganese hydrotalcite is prepared by hydrothermal carbonization, and finally the carbon-coated nitrogen-doped flower-shaped cobalt-manganese hydrotalcite is prepared by high-temperature roasting to prepare a carbon-coated nitrogen-doped flower-shaped cobalt-manganese composite oxide; therefore, the prepared carbon-coated nitrogen-doped flower-shaped cobalt-manganese composite oxide has a flower-shaped multi-stage regular structure and higher intrinsic conductivity and intrinsic activity, so that when the cobalt-manganese composite oxide is used for catalytically activating persulfate to degrade waste water, such as antibiotic waste water, the catalytic degradation activity and degradation rate of organic pollutants in the waste water are effectively improved, the pollutants are rapidly treated, and the cobalt-manganese composite oxide is easy to recycle after being used, so that secondary pollution can be prevented.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other related drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a schematic flow chart of an embodiment of a method for preparing a cobalt-manganese composite oxide according to the present invention.
The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially. In addition, the meaning of "and/or" appearing throughout includes three juxtapositions, exemplified by "A and/or B", including either A or B or both A and B. In addition, technical solutions between various embodiments may be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present invention. All other embodiments, which can be obtained by a person skilled in the art without inventive step based on the embodiments of the present invention, are within the scope of protection of the present invention.
At present, the transition metal oxide catalyzed persulfate activated by the transition metal oxide is considered as the most potential water purification method for degrading organic pollutants in antibiotic wastewater, but the intrinsic conductivity, the active site density and the intrinsic activity of the transition metal oxide still need to be further improved, and the problems of small size, difficult recycling from water and the like of the nano catalyst still exist in the method.
In view of this, the present invention provides a method for preparing nitrogen-doped flower-shaped cobalt-manganese composite oxide, which is a simple and easy process for preparing nitrogen-doped flower-shaped cobalt-manganese composite oxide, and fig. 1 shows an embodiment of the method for preparing nitrogen-doped flower-shaped cobalt-manganese composite oxide provided by the present invention. Referring to fig. 1, in the present embodiment, the method for preparing the nitrogen-doped flower-shaped cobalt-manganese composite oxide includes the following steps:
step S10, adding cobalt salt, manganese salt and polyalcohol amine into distilled water in sequence, stirring and mixing, heating to 80-160 ℃, carrying out hydrothermal reaction for 6-20 h, separating out a solid product, washing and drying to obtain nitrogen-doped flower-shaped cobalt-manganese hydrotalcite;
s20, adding the cobalt-manganese hydrotalcite into a glucose solution, heating to 120-200 ℃ to perform hydrothermal reaction for 6-12 h, separating out a solid product, washing and drying to obtain the cobalt-manganese hydrotalcite with the carbon modified surface;
and S30, heating the cobalt-manganese hydrotalcite with the carbon modified on the surface to 500-600 ℃ in a nitrogen atmosphere, preserving the heat for 0.5-2 h, washing and drying a roasted product, and thus obtaining the nitrogen-doped flower-shaped cobalt-manganese composite oxide.
According to the technical scheme provided by the invention, cobalt salt and manganese salt are used as precursors, polyalcohol amine is used as a nitrogen source, a precipitator and a structure directing agent, and during a hydrothermal reaction process, the polyalcohol amine is used for controlling the concentration of the precursors and the attraction to metal ions, regulating and controlling the nucleation number and the nucleation rate of hydrotalcite crystals and carrying out oriented connection and oriented growth to prepare the nitrogen-doped flower-shaped cobalt-manganese hydrotalcite; then adding the nitrogen-doped flower-shaped cobalt-manganese hydrotalcite into a glucose solution, and carrying out hydrothermal carbonization to obtain carbon-coated nitrogen-doped flower-shaped cobalt-manganese hydrotalcite; and finally, roasting the carbon-coated nitrogen-doped flower-shaped cobalt-manganese hydrotalcite at high temperature to prepare the carbon-coated nitrogen-doped flower-shaped cobalt-manganese composite oxide. Therefore, the prepared carbon-coated nitrogen-doped flower-shaped cobalt-manganese composite oxide has a flower-shaped multi-level regular structure and higher intrinsic conductivity and intrinsic activity, so that when the cobalt-manganese composite oxide is used for catalytically activating persulfate to degrade waste water, such as antibiotic waste water, the catalytic degradation activity and degradation rate of organic pollutants in the waste water are effectively improved, the pollutants are rapidly treated, and the cobalt-manganese composite oxide is easy to recycle after being used, so that secondary pollution can be prevented.
The hydrotalcite is mainly formed by orderly assembling sheet layers with positive charges and anions among the sheet layers, wherein metal cations in the sheet layers occupy the center of regular octahedral lattices, and the vertexes are connected by hydroxyl ions to form a two-dimensional structure capable of being expanded infinitely; the metal elements in the sheet layer can be isomorphously replaced by metal elements with similar radius, and can be prepared by a coprecipitation method, a hydrothermal method, an ion exchange method and the like. In the embodiment of the invention, cobalt salt and manganese salt are selected as metal sources for preparing hydrotalcite, and the hydrotalcite is prepared by a hydrothermal method and is made to generate layered hydrotalcite-like compound under an alkaline condition.
Specifically, coCl can be selected as the cobalt salt 2 、Co(NO 3 ) 2 And Co (CH) 3 COO) 2 That is, the cobalt salt may be any one of the above substances, or a mixture of any two or three of the above substances, and all of them fall within the scope of the present invention. More specifically, in the embodiment of the present invention, the cobalt salt is preferably prepared into a cobalt salt solution as a reaction raw material for standby, or added into water together with other raw materials and stirred and mixed.
The manganese salt can be MnCl 2 、Mn(NO 3 ) 2 And MnSO 4 At least one of the above substances, that is, the manganese salt can be any one of the substances, and can also be a mixture of any two or three of the substances, and the invention also belongs to the protection scope. More specifically, in the embodiment of the present invention, the manganese salt is preferably prepared into a cobalt salt solution as a reaction raw material for standby, or added into water together with other raw materials to be stirred and mixed.
When the hydrotalcite is prepared by a hydrothermal method, a weakly alkaline compound can be selected as a precipitator, such as diethanolamine, urea, triethanolamine and the like, so that the cobalt salt and the manganese salt can generate the layered hydrotalcite under the alkaline condition. In the embodiment of the invention, the polyalcohol amine is a nitrogen source, is also a precipitator and a structure directing agent, has weak alkalinity and strong complexation, can ensure that metal particles and hydroxide radicals slowly react at a lower concentration, and controls the nucleation number and the nucleation rate of hydrotalcite crystals, so that nitrogen elements are left in the hydrotalcite crystals to form the nitrogen-doped hydrotalcite. In addition, the coordination of polyols to metal particles exhibits a variety of coordination modes, such as terminal, chelating, or bridging, that can lead to self-assembly of polynuclear metal clusters; and also has excellent capability of forming hydrogen bonds, and is a high-efficiency structure directing agent.
In the embodiment of the invention, the polyalcohol amine is used as a structure directing agent to attract or induce metal ions and control the oriented connection and oriented growth of hydrotalcite crystals to form a flower-shaped structure assembled by a plurality of nano sheets; at least one of triethanolamine, ethanolamine and diethanolamine can be used, that is, the polyalcohol amine can be any one of the above substances, and can also be a mixture of any two or three of the substances, and the invention also belongs to the protection scope of the invention. Preferably, the polyalcohol amine is triethanolamine, and is used as a precipitator, a nitrogen source and a structure directing agent due to alkalescence, strong stability and complexation, is more suitable for the generation of nitrogen-doped hydrotalcite, and is also favorable for inducing the oriented connection and oriented growth of hydrotalcite crystals to form a flower-shaped structure.
Further, the cobalt salt, the manganese salt and the polyalcohol amine have the following raw material proportioning relationship: the molar ratio of the cobalt salt to the manganese salt is 1; the ratio of the total amount of metal ions such as cobalt salt and manganese salt to the amount of the polyhydric alcohol is 1; the total molar concentration of metal ions such as cobalt salt and manganese salt is 0.01-0.1M. Under the condition of the mixture ratio, the cobalt salt and the manganese salt can be completely converted into hydrotalcite without a large amount of residue, so that the waste of raw materials is avoided. In addition, the stirring operation in step S10 and the operation of separating the solid product from the reaction solution may be performed by conventional methods in the art, for example, mechanical stirring, magnetic stirring, etc. may be used for stirring, and solid-liquid separation may be performed by filtration, centrifugation, suction filtration, etc. for separating the solid product from the reaction solution.
The improvement of electron transfer capability and catalytic activity of the metal oxide is restricted due to low intrinsic conductivity of the metal oxide, and the surface modification of carbon and noble metal can be used as an effective method for improving the intrinsic conductivity of the metal oxide. In the embodiment of the invention, the intrinsic conductivity of the carbon is improved by adopting a mode of modifying the surface of the metal oxide with the carbon. Namely, the nitrating flower-shaped cobalt-manganese hydrotalcite prepared in the step S10 is added into a glucose solution, and is heated to 120-200 ℃ to carry out hydrothermal reaction for 6-12 h, so that glucose is hydrothermally carbonized on the surface of the nitrating flower-shaped cobalt-manganese hydrotalcite to form carbon particles. Further, in the embodiment of the present invention, the concentration of the glucose solution used is 0.005 to 0.02M; the solid-to-liquid ratio of the nitrogen-doped flower-like cobalt-manganese hydrotalcite to the glucose solution is 2-5 g/L, namely, every 2g of the cobalt-manganese hydrotalcite is correspondingly added into 2-5L of the glucose solution. Under the proportion, glucose can be completely converted into a small amount of uniformly dispersed carbon particles on the surface of the nitrogen-doped flower-shaped cobalt-manganese hydrotalcite, and the exposure of the surface active sites of the nitrogen-doped flower-shaped hydrotalcite can not be influenced.
Furthermore, the nitrogen-doped flower-like cobalt-manganese hydrotalcite is converted into a cobalt-manganese composite oxide with almost the same crystal structure in a high-temperature environment, namely the prepared cobalt-manganese composite oxide is formed by orderly assembling sheet layers with positive charges and sheet component anions, metal cations in the sheet layers are fixed in the center of a regular octahedron lattice, and the vertexes are connected by oxygen anions to form a two-dimensional structure capable of being expanded infinitely. Meanwhile, the hydrothermal carbon on the surface of the nitrogen-doped flower-shaped cobalt-manganese hydrotalcite is converted into pyrolytic carbon in a high-temperature environment, so that the conductivity of the material and the adhesive force of the carbon on the surface of an oxide are improved. Specifically, in the embodiment of the invention, the cobalt-manganese hydrotalcite with the carbon-modified surface is heated to 500-600 ℃ in a nitrogen atmosphere and then is subjected to heat preservation for 0.5-2 h, and the operation can be performed in equipment such as a tubular furnace, the equipment is simple and low in cost, the temperature rise rate in the temperature rise process is further set to be 1-5 ℃/min, so that incomplete conversion of the hydrotalcite caused by too high heating temperature can be avoided, unnecessary energy consumption caused by too low heating temperature can be avoided, and the process cost for preparing the material can be reduced.
The invention also provides a method for degrading antibiotic wastewater based on the advanced oxidation technology of the sulfuric acid free radical and the nitrogen-doped flower-shaped cobalt-manganese composite oxide prepared by the method provided by the invention. Specifically, in an embodiment of the method for degrading antibiotic wastewater provided by the present invention, the method for degrading antibiotic wastewater comprises the following steps:
adding the nitrogen-doped flower-shaped cobalt-manganese composite oxide into the antibiotic wastewater to be treated, then adding persulfate, stirring, heating to 30-50 ℃, reacting for 0.5-2 h, and finishing the degradation treatment of the antibiotic wastewater.
Specifically, in the embodiment of the present invention, the persulfate includes at least one of sodium persulfate, potassium persulfate, sodium monopersulfate, potassium monopersulfate and potassium monopersulfate, that is, the persulfate may be selected from any one of the above substances, or may be selected from a mixture of any two or more of the above substances, and all of them fall within the scope of the present invention.
Further, when the antibiotic wastewater is treated, the addition amounts of the nitrogen-doped flower-like cobalt-manganese composite oxide and the persulfate are as follows: 0.1-1 g of the nitrogen-doped flower-shaped cobalt-manganese composite oxide and 0.2-0.6 g of the persulfate are correspondingly added into each liter of antibiotic wastewater. Under the addition, the nitrogen-doped flower-shaped cobalt-manganese composite oxide can maximally catalyze and activate persulfate to form sulfuric acid free radicals, so that organic pollutants in antibiotic wastewater can be rapidly and effectively degraded, the nitrogen-doped flower-shaped cobalt-manganese composite oxide is particularly suitable for treating antibiotic wastewater with levofloxacin concentration of 50-200 mg/L, the degradation rate of levofloxacin is high, the rate is high, and the removal rate of levofloxacin can reach more than 95%.
The technical solutions of the present invention are further described in detail below with reference to specific examples and drawings, it should be understood that the following examples are merely illustrative of the present invention and are not intended to limit the present invention.
Example 1
(1) 0.001mol of CoCl 2 、0.003mol MnCl 2 And 0.02mol of triethanolamine are sequentially added into 100mL of distilled water, stirred, mixed and heated to 120 ℃ for hydrothermal reaction for 8 hours, then a solid product is separated out, and the solid product is washed and driedDrying to obtain nitrogen-doped flower-shaped cobalt-manganese hydrotalcite;
(2) Adding 20mg of the nitrogen-doped flower-shaped cobalt-manganese hydrotalcite prepared in the step (1) into 50mL of 0.01mol/L glucose solution, heating to 180 ℃ to perform hydrothermal reaction for 6h, separating out a solid product, washing and drying the solid product to obtain surface carbon modified nitrogen-doped flower-shaped cobalt-manganese hydrotalcite;
(3) Heating the surface carbon modified nitrogen-doped flower-shaped cobalt-manganese hydrotalcite prepared in the step (2) to 550 ℃ at a heating rate of 3 ℃/min in a nitrogen atmosphere, then preserving heat for 2 hours, then washing and drying the roasted product to obtain a surface carbon modified nitrogen-doped flower-shaped cobalt-manganese composite oxide, which is recorded as nitrogen-doped flower-shaped Mn x Co 3-x O 4 @C。
Example 2
(1) 0.001mol of CoCl 2 、0.002mol MnCl 2 Sequentially adding 0.018mol of triethanolamine into 100mL of distilled water, stirring, mixing, heating to 110 ℃, carrying out hydrothermal reaction for 12h, separating out a solid product, washing and drying the solid product, and obtaining the nitrogen-doped flower-shaped cobalt-manganese hydrotalcite;
(2) Adding 20mg of the nitrogen-doped flower-shaped cobalt-manganese hydrotalcite prepared in the step (1) into 40mL of 0.01mol/L glucose solution, heating to 160 ℃ to perform hydrothermal reaction for 8 hours, separating out a solid product, washing and drying the solid product to obtain surface carbon modified nitrogen-doped flower-shaped cobalt-manganese hydrotalcite;
(3) Heating the surface carbon modified nitrogen-doped flower-shaped cobalt-manganese hydrotalcite prepared in the step (2) to 500 ℃ at a heating rate of 5 ℃/min in a nitrogen atmosphere, then preserving heat for 2 hours, then washing and drying the roasted product to obtain a surface carbon modified nitrogen-doped flower-shaped cobalt-manganese composite oxide, which is recorded as nitrogen-doped flower-shaped Mn x Co 3-x O 4 @C。
Example 3
(1) 0.002mol of CoCl was added 2 、0.002mol MnCl 2 And 0.02mol of triethanolamine are sequentially added into 100mL of distilled water, stirred, mixed and heated to 120 ℃ for hydrothermal reaction for 12h, then a solid product is separated out, and the solid product is washed and dried to obtain the nitrogen-doped flower-shaped cobalt-manganese hydrotalcite；
(2) Adding 20mg of the nitrogen-doped flower-shaped cobalt-manganese hydrotalcite prepared in the step (1) into 30mL of 0.01mol/L glucose solution, heating to 180 ℃ to perform hydrothermal reaction for 8 hours, separating out a solid product, washing and drying the solid product to obtain surface carbon modified nitrogen-doped flower-shaped cobalt-manganese hydrotalcite;
(3) Heating the surface carbon modified nitrogen-doped flower-shaped cobalt-manganese hydrotalcite prepared in the step (2) to 550 ℃ at a heating rate of 5 ℃/min in a nitrogen atmosphere, then preserving heat for 1h, washing and drying the roasted product to obtain a surface carbon modified nitrogen-doped flower-shaped cobalt-manganese composite oxide, which is recorded as nitrogen-doped flower-shaped Mn x Co 3-x O 4 @C。
Example 4
(1) 0.002mol of Co (NO) 3 ) 2 、0.001mol Mn(NO 3 ) 2 Sequentially adding 0.015mol of diethanolamine and 100mL of distilled water, stirring, mixing, heating to 80 ℃ for hydrothermal reaction for 20h, separating out a solid product, washing and drying the solid product to obtain the nitrogen-doped flower-shaped cobalt-manganese hydrotalcite;
(2) Adding 20mg of the nitrogen-doped flower-like cobalt-manganese hydrotalcite prepared in the step (1) into 20mL of 0.02mol/L glucose solution, heating to 120 ℃, performing hydrothermal reaction for 12 hours, separating out a solid product, washing and drying the solid product, and thus obtaining surface carbon modified nitrogen-doped flower-like cobalt-manganese hydrotalcite;
(3) Heating the surface carbon modified nitrogen-doped flower-shaped cobalt-manganese hydrotalcite prepared in the step (2) to 600 ℃ at a heating rate of 1 ℃/min in a nitrogen atmosphere, then preserving heat for 0.5h, then washing and drying the roasted product to obtain a surface carbon modified nitrogen-doped flower-shaped cobalt-manganese composite oxide, which is marked as nitrogen-doped flower-shaped Mn x Co 3-x O 4 @C。
Example 5
(1) 0.002mol of CoCl (CH) 3 COO) 2 、0.001mol MnSO 4 And 0.02mol of ethanolamine are sequentially added into 100mL of distilled water, stirred, mixed and heated to 160 ℃ for hydrothermal reaction for 6h, then a solid product is separated out, and the solid product is washed and dried to obtain the nitrogen-doped flower-shaped cobalt-manganese waterTalc;
(2) Adding 20mg of the nitrogen-doped flower-shaped cobalt-manganese hydrotalcite prepared in the step (1) into 50mL0.005mol/L glucose solution, heating to 200 ℃ to perform hydrothermal reaction for 12h, separating out a solid product, washing and drying the solid product to obtain surface carbon modified nitrogen-doped flower-shaped cobalt-manganese hydrotalcite;
(3) Heating the surface carbon modified nitrogen-doped flower-shaped cobalt-manganese hydrotalcite prepared in the step (2) to 500 ℃ at a heating rate of 3 ℃/min in a nitrogen atmosphere, then preserving heat for 2 hours, then washing and drying the roasted product to obtain a surface carbon modified nitrogen-doped flower-shaped cobalt-manganese composite oxide, which is recorded as nitrogen-doped flower-shaped Mn x Co 3-x O 4 @C。
Application example 1
0.05g of the nitrogen-doped flower-like Mn obtained in example 1 was taken x Co 3-x O 4 @ C, adding into 100mL levofloxacin solution with concentration of 100mg/L, adding 0.05g potassium monopersulfate, stirring, heating to 30 ℃, and oscillating for 30min.
Sampling every 5min in the catalytic reaction process, adding a quenching agent to stop the reaction, and measuring the concentration of the levofloxacin by adopting a spectrophotometry after removing the solid catalyst from the sample. In the embodiment, the degradation of levofloxacin conforms to a first-order kinetic equation, the removal rate of levofloxacin reaches 93.2% within 30min, the concentration of dissolved cobalt ions is 0.0025mg/L, and the concentration of dissolved manganese ions is 0.0032mg/L.
Application example 2
0.01g of the nitrogen-doped flower-like Mn obtained in example 2 was taken x Co 3-x O 4 @ C, adding 100mL of levofloxacin with the concentration of 50mg/L, adding 0.02g of potassium monopersulfate, stirring uniformly, heating to 40 ℃, and carrying out oscillation reaction for 30min.
Sampling every 5min in the catalytic reaction process, adding a quenching agent to stop the reaction, and measuring the concentration of the levofloxacin by adopting a spectrophotometry after removing the solid catalyst from the sample. In the embodiment, the degradation of levofloxacin conforms to a first-order kinetic equation, the removal rate of levofloxacin reaches 95.7% within 30min, the concentration of dissolved cobalt ions is 0.0078mg/L, and the concentration of dissolved manganese ions is 0.0023mg/L.
Application example 3
0.04g of nitrogen-doped flower-like Mn obtained in example 3 was taken x Co 3-x O 4 @ C, adding into 100mL levofloxacin solution with concentration of 150mg/L, adding 0.04g potassium monopersulfate, stirring, heating to 50 deg.C, and reacting under shaking for 0.5h.
Sampling every 5min in the catalytic reaction process, removing the solid catalyst from the sample, adding a quenching agent to terminate the reaction, and measuring the concentration of the levofloxacin by adopting a spectrophotometry. In the embodiment, the degradation of levofloxacin conforms to a first-order kinetic equation, the removal rate of levofloxacin reaches 92.3% within 30min, the concentration of dissolved cobalt ions is 0.0052mg/L, and the concentration of dissolved manganese ions is 0.0015mg/L.
Application example 4
0.03g of the nitrogen-doped flower-like Mn obtained in example 4 was taken x Co 3-x O 4 @ C, adding into 100mL levofloxacin solution with concentration of 100mg/L, adding 0.03g potassium hydrogen persulfate, stirring, heating to 35 deg.C, and reacting for 60min with oscillation.
Sampling every 5min in the catalytic reaction process, removing the solid catalyst from the sample, adding a quenching agent to terminate the reaction, and measuring the concentration of the levofloxacin by adopting a spectrophotometry. In the embodiment, the degradation of levofloxacin conforms to a first-order kinetic equation, the removal rate of levofloxacin reaches 96.3% within 30min, the concentration of dissolved cobalt ions is 0.0052mg/L, and the concentration of dissolved manganese ions is 0.0027mg/L.
Application example 5
0.1g of the nitrogen-doped flower-like Mn obtained in example 5 was taken x Co 3-x O 4 @ C, adding into 100mL levofloxacin solution with concentration of 200mg/L, adding 0.06g sodium persulfate, stirring well, heating to 45 deg.C, and shaking for reaction for 120min.
Sampling every 5min in the catalytic reaction process, removing the solid catalyst from the sample, adding a quenching agent to terminate the reaction, and measuring the concentration of the levofloxacin by adopting a spectrophotometry. In the embodiment, the degradation of levofloxacin conforms to a first order kinetic equation, the removal rate of levofloxacin reaches 89.6 percent within 30min, the concentration of dissolved cobalt ions is 0.0062mg/L, and the concentration of dissolved manganese ions is 0.0021mg/L.
Application examples 6 to 10
0.02g each of the nitrogen-doped flower-like Mn prepared in examples 1 to 5 was taken at normal temperature and pressure x Co 3-x O 4 @ C, adding 100mL of levofloxacin solution with the concentration of 100mg/L, adding 0.06g of potassium monopersulfate, adjusting the pH to 3.0, and then heating to 30 ℃ for reaction for 30min with shaking.
Sampling every 5min in the reaction process, adding a quenching agent to terminate the reaction after removing the solid catalyst from the sample, measuring the concentration of the levofloxacin by adopting a spectrophotometry, and calculating the removal rate of the levofloxacin after 30min as shown in the following table 1.
Application examples 11 to 15
0.02g each of the nitrogen-doped flower-like Mn prepared in examples 1 to 5 was taken at normal temperature and pressure x Co 3-x O 4 @ C, adding 100mL of levofloxacin solution with the concentration of 100mg/L, adding 0.06g of potassium monopersulfate, adjusting the pH to 5.0, and heating to 30 ℃ for reaction for 30min with shaking.
Sampling every 5min in the reaction process, adding a quenching agent to stop the reaction after removing the solid catalyst from the sample, measuring the concentration of the levofloxacin by adopting a spectrophotometry, and calculating the levofloxacin removal rate after 30min as shown in the following table 1.
Application examples 16 to 20
0.02g each of the nitrogen-doped flower-like Mn prepared in examples 1 to 5 was taken at normal temperature and pressure x Co 3-x O 4 @ C, adding 100mL of levofloxacin solution with the concentration of 100mg/L, adding 0.06g of potassium monopersulfate, adjusting the pH to 7.0, and heating to 30 ℃ for reaction for 30min with shaking.
Sampling every 5min in the reaction process, adding a quenching agent to stop the reaction after removing the solid catalyst from the sample, measuring the concentration of the levofloxacin by adopting a spectrophotometry, and calculating the levofloxacin removal rate after 30min as shown in the following table 1.
Application examples 21 to 25
0.02g each of the nitrogen-doped flower-like Mn prepared in examples 1 to 5 was taken at normal temperature and pressure x Co 3-x O 4 @ C, adding 100mL of levofloxacin solution with the concentration of 100mg/L, adding 0.06g of potassium monopersulfate, adjusting the pH to 9.0, and then heating to 30 ℃ for reaction for 30min with shaking.
Sampling every 10min in the reaction process, adding a quenching agent to terminate the reaction after removing the solid catalyst from the sample, measuring the concentration of the levofloxacin by adopting a spectrophotometry, and calculating the removal rate of the levofloxacin after 30min as shown in the following table 1.
Comparative examples 1 to 4
At normal temperature and normal pressure, 0.02g of commercial hydrotalcite calcined substance is taken as a catalyst, added into 100mL of levofloxacin solution with the concentration of 100mg/L, then added with 0.06g of potassium monopersulfate, and respectively adjusted to pH 3.0, 5.0, 7.0 and 9.0, and then heated to 30 ℃ for oscillation reaction for 30min.
Sampling is carried out for 30min in the reaction process, after the solid catalyst is removed from the sample, a quenching agent is added to terminate the reaction, the concentration of the levofloxacin is measured by adopting a spectrophotometry, and the calculation result of the removal rate of the levofloxacin after 30min is shown in the following table 1.
TABLE 1 Effect of catalytic degradation of the catalyst prepared in each example and the comparative example at different pH of the solution
The pH value of the solution influences the acidity of the surface of the catalyst, the generation of active species and the degradation of pollutants. As can be seen from the test results in Table 1, the nitrogen-doped flower-like Mn prepared in the examples of the present invention x Co 3-x O 4 The @ C is used as a catalyst for catalytically activating the peroxymonosulfate to degrade the antibiotic wastewater, and due to the flower-shaped multi-level regular structure and the high intrinsic conductivity and intrinsic activity, the catalyst has excellent catalytic degradation effect in both an acidic solution and a neutral solution, the removal rate of levofloxacin in the antibiotic wastewater can reach over 90 percent within 30min, and the organic pollutants can be rapidly and thoroughly treated.Similar to most common catalysts, the catalyst prepared in the embodiment of the invention has a slightly weak catalytic degradation effect in an alkaline solution, but the catalytic activity of the catalyst is far higher than that of the common catalyst, and the removal rate of levofloxacin in antibiotic wastewater can reach about 80% within 30min.
In order to further analyze the stability of the catalysts prepared in examples 1 to 5 of the present invention in catalyzing the degradation of antibiotic wastewater by sodium persulfate, the recycling performance thereof was tested, and the method and results were as follows:
0.02g of the nitrogen-doped flower-like Mn prepared in examples 1 to 5 was taken at normal temperature and pressure x Co 3-x O 4 Adding @ C serving as a catalyst into 100mL of levofloxacin solution with the concentration of 100mg/L, adding 0.06g of sodium persulfate, uniformly mixing, heating to 30 ℃, and carrying out oscillation reaction for 3 hours; after the reaction is finished, the solid catalyst is recovered, then the solid catalyst is washed and dried, and the catalyst is recycled, wherein the recycling times and the corresponding statistical results of the levofloxacin removal rate are shown in the following table 2.
TABLE 2 catalytic degradation effect of catalyst recycle in each example
Nitrogen-doped flower-shaped Mn prepared by the embodiment of the invention x Co 3-x O 4 The @ C is used as a catalyst for catalyzing and activating persulfate to degrade antibiotic wastewater, has a layered structure similar to hydrotalcite, and metal cations in the sheet layer are fixed in regular octahedral lattice centers and are not easy to dissolve out, so that the crystal structure and the stability of catalytic activity of the catalyst are excellent. Further, as can be seen from the test results in table 2, the catalytic degradation effect of the catalyst prepared in the embodiment of the present invention is almost the same as that of the catalyst used for the first time during the fifth reuse, the catalyst still has the excellent catalytic degradation effect during the tenth reuse, and the removal rate of the antibiotic wastewater can reach about 83% within 30min, which indicates that the nitrogen-doped flower-shaped Mn prepared in the embodiment of the present invention x Co 3-x O 4 @ C for degrading antibiotic wastewater by catalytically activating persulfateThe catalyst also has the advantage of being recyclable.
The above is only a preferred embodiment of the present invention, and it is not intended to limit the scope of the invention, and various modifications and changes will occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention shall be included in the scope of the present invention.
Claims (10)
1. A preparation method of a nitrogen-doped flower-shaped cobalt-manganese composite oxide is characterized by comprising the following steps:
adding cobalt salt, manganese salt and polyalcohol amine into distilled water in sequence, stirring and mixing, heating to 80-160 ℃, carrying out hydrothermal reaction for 6-20 h, separating out a solid product, washing and drying to obtain nitrogen-doped flower-shaped cobalt-manganese hydrotalcite;
adding the cobalt-manganese hydrotalcite into a glucose solution, heating to 120-200 ℃ to perform hydrothermal reaction for 6-12 h, separating out a solid product, washing and drying to obtain the cobalt-manganese hydrotalcite with the carbon modified surface;
and heating the cobalt-manganese hydrotalcite with the carbon-modified surface to 500-600 ℃ in a nitrogen atmosphere, preserving the heat for 0.5-2 h, washing and drying a roasted product, and thus obtaining the nitrogen-doped flower-shaped cobalt-manganese composite oxide.
2. The method of preparing nitrogen-doped flower-like cobalt-manganese composite oxide according to claim 1, wherein said cobalt salt comprises CoCl 2 、Co(NO 3 ) 2 And Co (CH) 3 COO) 2 At least one of (a).
3. The method of preparing nitrogen-doped flower-like cobalt-manganese composite oxide according to claim 1, wherein said manganese salt comprises MnCl 2 、Mn(NO 3 ) 2 And MnSO 4 At least one of (1).
4. The method of producing the nitrogen-doped flower-like cobalt-manganese composite oxide according to claim 1, wherein the polyalcohol amine comprises at least one of triethanolamine, ethanolamine, and diethanolamine.
5. The method for preparing nitrogen-doped flower-like cobalt-manganese composite oxide according to claim 1, wherein the steps of sequentially adding cobalt salt, manganese salt and polyalcohol amine into distilled water, stirring and mixing, heating to 80-160 ℃ for hydrothermal reaction for 6-20 h, separating out solid products, washing and drying to obtain nitrogen-doped flower-like cobalt-manganese hydrotalcite are as follows:
the molar ratio of the cobalt salt to the manganese salt is 1;
the ratio of the total amount of the metal ions such as the cobalt salt and the manganese salt to the amount of the polyhydric alcohol is 1 to 8;
the total molar concentration of metal ions such as cobalt salt and manganese salt is 0.01-0.1M.
6. The method for preparing nitrogen-doped flower-like cobalt-manganese composite oxide according to claim 1, wherein the cobalt-manganese hydrotalcite is added into glucose solution, heated to 120-200 ℃ for hydrothermal reaction for 6-12 h, and the solid product is separated and washed and dried to obtain the cobalt-manganese hydrotalcite with carbon modified surface:
the concentration of the glucose solution is 0.005-0.02M;
adding 2-5L of the glucose solution into every 2g of the cobalt-manganese hydrotalcite.
7. The method for preparing nitrogen-doped flower-like cobalt-manganese composite oxide according to claim 1, wherein in the nitrogen atmosphere, the cobalt-manganese hydrotalcite with the carbon-modified surface is heated to 500-600 ℃ and then is kept warm for 0.5-2 h, and the roasted product is washed and dried to obtain the nitrogen-doped flower-like cobalt-manganese composite oxide:
the heating rate is 1-5 ℃/min in the process of heating to 500-600 ℃.
8. A method for degrading antibiotic wastewater, which is characterized by comprising the following steps:
adding a nitrogen-doped flower-shaped cobalt-manganese composite oxide into the antibiotic wastewater to be treated, then adding persulfate, stirring, heating to 30-50 ℃, reacting for 0.5-2 h, and completing the degradation treatment of the antibiotic wastewater;
wherein the nitrogen-doped flower-shaped cobalt-manganese composite oxide is prepared by the preparation method of the nitrogen-doped flower-shaped cobalt-manganese composite oxide as claimed in any one of claims 1 to 7.
9. The method of degrading antibiotic wastewater of claim 8 wherein the persulfate salt comprises at least one of sodium persulfate, potassium persulfate, sodium monopersulfate, potassium monopersulfate, and potassium monopersulfate.
10. The method for degrading antibiotic wastewater according to claim 8, wherein 0.1 to 1g of the nitrogen-doped flower-like cobalt manganese composite oxide and 0.2 to 0.6g of the persulfate are added to each liter of antibiotic wastewater.
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| CN110538648A (en) * | 2018-12-21 | 2019-12-06 | 天津大学 | Flower-shaped hierarchical pore structure hydrotalcite-like material, preparation method of catalyst and application of catalyst in propane dehydrogenation |
| CN110560080A (en) * | 2019-09-19 | 2019-12-13 | 武汉轻工大学 | preparation method of cobalt-manganese composite oxide and method for degrading dye wastewater |
| CN112044367A (en) * | 2020-08-07 | 2020-12-08 | 暨南大学 | Cobalt-manganese hydrotalcite aerogel and preparation method and application thereof |
| CN113333007A (en) * | 2021-04-28 | 2021-09-03 | 暨南大学 | Nitrogen-doped cobalt iron/carbon catalyst capable of efficiently activating persulfate and preparation method and application thereof |
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2022
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110538648A (en) * | 2018-12-21 | 2019-12-06 | 天津大学 | Flower-shaped hierarchical pore structure hydrotalcite-like material, preparation method of catalyst and application of catalyst in propane dehydrogenation |
| CN110560080A (en) * | 2019-09-19 | 2019-12-13 | 武汉轻工大学 | preparation method of cobalt-manganese composite oxide and method for degrading dye wastewater |
| CN112044367A (en) * | 2020-08-07 | 2020-12-08 | 暨南大学 | Cobalt-manganese hydrotalcite aerogel and preparation method and application thereof |
| CN113333007A (en) * | 2021-04-28 | 2021-09-03 | 暨南大学 | Nitrogen-doped cobalt iron/carbon catalyst capable of efficiently activating persulfate and preparation method and application thereof |
Non-Patent Citations (2)
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| XIUFEI ZHAO等: "Co-Mn layered double hydroxide as an effective heterogeneous catalyst for degradation of organic dyes by activation of peroxymonosulfate" * |
| YANI LIU等: "Origin of the Enhanced Reusability and Electron Transfer of the Carbon-Coated Mn3O4 Nanocube for Persulfate Activation" * |
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