CN112642461B - Modified cuprous ferrite catalyst rich in oxygen vacancies and preparation method and application thereof - Google Patents

Modified cuprous ferrite catalyst rich in oxygen vacancies and preparation method and application thereof Download PDF

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CN112642461B
CN112642461B CN202011608292.9A CN202011608292A CN112642461B CN 112642461 B CN112642461 B CN 112642461B CN 202011608292 A CN202011608292 A CN 202011608292A CN 112642461 B CN112642461 B CN 112642461B
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chitosan
cuprous
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ferrite
iron
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CN112642461A (en
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刘波
王梦良
周德超
汪中杰
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Jiangsu Dongfang Weide Environmental Protection Technology Co ltd
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    • 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
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    • 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
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    • 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
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    • 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
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    • C02F2305/02—Specific form of oxidant
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Abstract

The invention provides a modified cuprous ferrite catalyst rich in oxygen vacancies and a preparation method and application thereof, belonging to the technical field of sewage treatment. In the method, the degree of hydrothermal deacetylation of chitosan is increased in an alkaline hydrothermal environment, the chitosan is hydrolyzed into chitosan oligosaccharide and glucosamine, the pH value of the solution is increased, the glucosamine is unstable in property, oxygen is easily consumed, Maillard non-enzymatic browning reaction is carried out to generate reduction ketone, unsaturated aldehyde and aromatic ring substances (such as pyrazine heterocycle, pyran, furan, pyrrole and the like), and an anoxic reduction environment is caused, and the environment is favorable for cuprous ferrite CuFeO 2 A large amount of oxygen vacancies are formed, and simultaneously, reduction ketones and unsaturated aldehydes generated by the hydrolysis of the chitosan are used as cuprous ferrite CuFeO 2 And the synthesized reducing agent, namely chitosan is derived into nitrogen-doped carbon nano particles, so that the modified cuprous ferrite catalyst rich in oxygen vacancies is obtained.

Description

Modified cuprous ferrite catalyst rich in oxygen vacancies and preparation method and application thereof
Technical Field
The invention relates to the technical field of sewage treatment, in particular to a modified cuprous ferrite catalyst rich in oxygen vacancies and a preparation method and application thereof.
Background
In recent years, advanced oxidation processes have been widely used in sewage treatment. The fenton reaction is one of the most efficient methods, and can generate the second largest oxidant hydroxyl radical next to fluorine to effectively degrade pollutants. The Fenton method has the advantages of simple operation, mild reaction conditions, high degradation efficiency, cheap raw materials and the like. However, the conventional homogeneous fenton reaction has certain disadvantages, for example, the reaction needs to be carried out at a pH of about 3; subsequently, a large amount of iron mud is generated, and even secondary pollution of acid or metal ions can be generated.
In order to overcome the problems, researchers prepare heterogeneous fenton-like catalysts by preparing active components containing transition metal elements except iron, such as copper, zinc and the like into solids or fixing the active components on the solids by certain technical means. The oxidation reduction of the main catalytic metal component is promoted through the synergistic action of double metals, the electron transfer rate in a system is accelerated, and finally, the free radical with strong oxidizing property is generated through an interface reaction to oxidize and degrade organic pollutants, so that the reaction under a neutral condition is realized, and the generation of iron mud is greatly reduced. Wherein, the cuprous ferrite (CuFeO) 2 ) The method has been a research hotspot due to the characteristics of simple preparation, low cost and high catalytic performance, but CuFeO 2 Spontaneous agglomeration can result due to their inherent high surface energy and low charge density, resulting in a reduction in the number of active sites and catalytic efficiency.
Disclosure of Invention
The invention aims to provide a modified cuprous ferrite catalyst rich in oxygen vacancies, and a preparation method and application thereof.
In order to achieve the above object, the present invention provides the following technical solutions:
the invention provides a preparation method of a modified cuprous ferrite catalyst, which comprises the following steps:
mixing a chitosan solution and an iron-copper metal salt solution, dripping the obtained mixed solution into alkali, and carrying out precipitation reaction to obtain an iron-copper precipitation mixed solution coated with chitosan;
and carrying out hydrothermal reaction on the iron-copper precipitate mixed solution coated with the chitosan, and drying to obtain the modified cuprous ferrite catalyst.
Preferably, the chitosan solution is prepared by dissolving chitosan in glacial acetic acid solution to obtain chitosan solution.
Preferably, the mass concentration of the glacial acetic acid solution is 2%, and the dosage ratio of the chitosan to the glacial acetic acid solution is (100-400) mg: 20 mL.
Preferably, the dosage ratio of copper salt and iron salt in the chitosan solution and the iron-copper metal salt solution is (100-400) mg:5mmol:5 mmol.
Preferably, the alkali is a sodium hydroxide aqueous solution, and the molar ratio of sodium hydroxide in the sodium hydroxide aqueous solution to copper salt in the iron-copper metal salt solution is (0.04-0.1): 5.
Preferably, the temperature of the hydrothermal reaction is 160-200 ℃ and the time is 10-15 h.
Preferably, the drying temperature is 50-80 ℃, and the drying time is 6-12 h.
The invention provides a modified cuprous ferrite catalyst prepared by the preparation method in the technical scheme, which comprises cuprous cupferroate and nitrogen-doped carbon nanoparticles loaded on the surface of the cuprous ferrite.
Preferably, the loading amount of the nitrogen-doped carbon nanoparticles on the cuprous ferrite is 9-30% by mass percentage.
The invention provides application of the modified cuprous ferrite catalyst in the technical scheme in catalyzing hydrogen peroxide to degrade pollutants.
The invention provides a preparation method of a modified cuprous ferrite catalyst, which comprises the following steps: mixing a chitosan solution and an iron-copper metal salt solution, dripping the obtained mixed solution into alkali, and carrying out precipitation reaction to obtain an iron-copper precipitation mixed solution coated with chitosan; and carrying out hydrothermal reaction on the iron-copper precipitate mixed solution coated with the chitosan, and drying to obtain the modified cuprous ferrite catalyst. In the method, the degree of hydrothermal deacetylation of chitosan is increased in an alkaline hydrothermal environment, the chitosan is hydrolyzed into chitosan oligosaccharide and glucosamine, the pH value of the solution is increased, the glucosamine is unstable in property, oxygen is easily consumed, Maillard non-enzymatic browning reaction is carried out, and reduction ketone, unsaturated aldehyde and aromatic ring substances (such as pyrazine heterocycle, pyran, furan, pyrrole and the like) are generated, so that an anoxic environment is generated, and the anoxic environment is favorable for cuprous ferrite CuFeO 2 Form a large amount ofOxygen vacancy, and simultaneously, reducing ketones and unsaturated aldehydes generated by the hydrolysis of chitosan are used as cuprous ferrite CuFeO 2 The synthesized reducing agent, namely the chitosan is derived into nitrogen-doped carbon nano particles, so that the modified cuprous ferrite catalyst rich in oxygen vacancies is obtained.
The modified cuprous ferrite prepared by the method is prepared in CuFeO 2 The surface is coated with a layer of nitrogen-doped carbon nano particles, so that the spontaneous agglomeration of the nitrogen-doped carbon nano particles can be effectively inhibited, and the problem of the agglomeration of the existing cuprous ferrite is solved.
The method of the invention does not need to add chemical reducing agent, and the pH value of the solution is increased due to the hydrolysis of the chitosan, so that the adding amount of alkali can be reduced, and secondary pollution can not be generated.
The invention provides application of the modified cuprous ferrite catalyst in catalyzing hydrogen peroxide to degrade pollutants, wherein unpaired electrons in oxygen vacancies of the modified cuprous ferrite catalyst prepared by the invention can be H 2 O 2 Adsorption provides abundant active sites, and oxygen vacancies can stretch and weaken H 2 O 2 By a O-O bond in (1), lowering H 2 O 2 Activation energy of OH to further convert H 2 O 2 The catalyst is activated to OH, the pH application range of the catalyst is widened, and the degradation effect on organic pollutants in the heterogeneous Fenton-like reaction process is improved.
Drawings
FIG. 1 is an XRD pattern of the catalysts prepared in example 1 and comparative example 1;
FIG. 2 is a Raman spectrum of the catalysts prepared in example 1 and comparative example 1;
FIG. 3 is an EPR spectrum of the catalysts prepared in example 1 and comparative example 1;
FIG. 4 is a graph of the effect of different materials on RhB removal under neutral conditions;
FIG. 5 shows OV-CuFeO prepared in example 1 2 Experimental graphs for the reusability of @ N-CNPs;
FIG. 6 is a graph showing the effect of catalysts prepared in examples 1 to 3 and comparative example 1 on the removal of RhB.
Detailed Description
The invention provides a preparation method of a modified cuprous ferrite catalyst, which comprises the following steps:
mixing a chitosan solution and an iron-copper metal salt solution, dripping the obtained mixed solution into alkali, and carrying out precipitation reaction to obtain an iron-copper precipitation mixed solution coated with chitosan;
and carrying out hydrothermal reaction on the iron-copper precipitate mixed solution coated with the chitosan, and drying to obtain the modified cuprous ferrite catalyst.
In the present invention, unless otherwise specified, all the required starting materials for the preparation are commercially available products well known to those skilled in the art.
The method comprises the steps of mixing a chitosan solution and an iron-copper metal salt solution, dripping the obtained mixed solution into alkali, and carrying out precipitation reaction to obtain an iron-copper precipitation mixed solution coated with chitosan. In the present invention, the preparation process of the chitosan solution is preferably to dissolve chitosan in glacial acetic acid solution to obtain chitosan solution. In the invention, the mass concentration of the glacial acetic acid solution is preferably 2%, and the dosage ratio of the chitosan to the glacial acetic acid solution is preferably (100-400) mg: 20mL, more preferably (200-350) mg: 20mL, more preferably (250-300) mg: 20 mL. In the present invention, after the chitosan is dissolved in the glacial acetic acid solution, the present invention preferably allows the resulting mixed solution to stand overnight to remove air bubbles, thereby obtaining a chitosan solution.
In the invention, the iron salt in the iron-copper metal salt solution is preferably iron sulfate heptahydrate, and the copper salt is preferably copper nitrate trihydrate; the method for preparing the iron-copper metal salt solution is not particularly limited in the present invention, and the copper salt and the iron salt are dissolved in ultrapure water according to a method well known in the art.
In the invention, the dosage ratio of the copper salt and the iron salt in the chitosan solution and the iron-copper metal salt solution is preferably (100-400) mg:5mmol:5mmol, more preferably (200-350) mg:5mmol:5mmol, and further preferably (250-300) mg:5mmol:5 mmol.
In the invention, the process of mixing the chitosan solution and the iron-copper metal salt solution is preferably to slowly add the iron-copper metal salt solution into the chitosan solution and stir the mixture to be uniformly mixed. The process of slowing and stirring is not particularly limited in the present invention and may be carried out according to a process well known in the art.
After the mixing is finished, the mixed solution is dripped into alkali for precipitation reaction. The dropping rate is not particularly limited in the present invention, and may be carried out according to a procedure well known in the art. In the invention, the alkali is preferably an aqueous sodium hydroxide solution, and the concentration of the aqueous sodium hydroxide solution is preferably 1.67 mol/L; the molar ratio of the sodium hydroxide in the sodium hydroxide aqueous solution to the copper salt in the iron-copper metal salt solution is preferably (0.04-0.1): 5, and more preferably (0.05-0.07): 5.
In the present invention, the temperature of the precipitation reaction is preferably room temperature, and the time is preferably 60 min. In the precipitation reaction process, iron ions and copper ions in the iron-copper metal salt solution are precipitated under an alkaline condition to obtain iron-copper hydroxide precipitate.
After the iron-copper precipitation mixed solution coated with chitosan is obtained, the iron-copper precipitation mixed solution coated with chitosan is subjected to hydrothermal reaction, and the modified cuprous ferrite catalyst is obtained after drying. According to the invention, the iron-copper precipitation mixed solution coated with chitosan is preferably subjected to ultrasonic treatment for 10min, and then subjected to hydrothermal reaction; the power of the ultrasound is not particularly limited in the present invention, and may be performed according to the ultrasound power well known in the art. The invention improves the dispersibility of the iron-copper precipitate by ultrasonic to obtain the cuprous ferrite with uniform load.
In the invention, the hydrothermal reaction is preferably carried out in a stainless steel reaction kettle with a polytetrafluoroethylene lining; the temperature of the hydrothermal reaction is preferably 160-200 ℃, more preferably 170-180 ℃, and the time is preferably 10-15 hours, more preferably 12-14 hours. In the hydrothermal reaction process, the degree of hydrothermal deacetylation of chitosan is increased in a high-temperature alkaline environment, the chitosan is hydrolyzed into chitosan oligosaccharide and glucosamine, the pH value of the solution is increased, the glucosamine is unstable in property, oxygen is easily consumed, Maillard non-enzymatic browning reaction is carried out to generate reduction ketone, unsaturated aldehydes and aromatic ring substances (such as pyrazine heterocycles, pyran, furan, pyrrole and the like) so as to cause an anoxic environment,the anoxic environment is favorable for the cuprous ferrite CuFeO 2 A large amount of oxygen vacancies are formed, and reduction ketones and unsaturated aldehydes generated by the hydrolysis of the chitosan are used as cuprous ferrite CuFeO 2 And (3) deriving the synthesized reducing agent, namely chitosan into nitrogen-doped carbon nano particles, thereby obtaining the nitrogen-doped carbon nano particle modified cuprous ferrite catalyst rich in oxygen vacancies.
After the hydrothermal reaction is finished, the obtained product is preferably centrifugally washed until the surface of the product is neutral, and then the product is dried to obtain the cuprous ferrite catalyst. In the invention, the drying mode is preferably vacuum drying, the drying temperature is preferably 50-80 ℃, more preferably 60 ℃, and the drying time is preferably 6-12 hours, more preferably 8-10 hours.
The invention provides a modified cuprous ferrite catalyst prepared by the preparation method of the technical scheme, which comprises cuprous ferrite and nitrogen-doped carbon nanoparticles loaded on the surface of the cuprous ferrite. In the invention, the loading amount of the nitrogen-doped carbon nanoparticles on the cuprous ferrite is preferably 9-30% by mass, and more preferably 9.3%, 17.7% or 29.8%.
The invention provides application of the modified cuprous ferrite catalyst in the technical scheme in catalyzing hydrogen peroxide to degrade pollutants. The method for applying the modified cuprous ferrite catalyst is not particularly limited, and the modified cuprous ferrite catalyst is used for catalyzing hydrogen peroxide to degrade pollutants according to a method well known in the art. In the embodiment of the invention, rhodamine B (RhB) is specifically used as a simulated pollutant molecule, and the Fenton-like catalytic degradation capability of the modified cuprous ferrite catalyst is evaluated; the specific method is that the concentration is 10 mg.L in 50mL -1 Adding 50mg of the modified cuprous ferrite catalyst into the dye solution, adjusting the pH value (namely, the pH value is 6.8), ultrasonically dispersing the obtained suspension in the dark for 2min, then placing a beaker on a magnetic stirrer for stirring, adding 255uL of H with the mass fraction of 30 percent 2 O 2 Starting catalytic reaction and timing; sampling when the catalytic reaction is carried out for 0min, 10min, 20min, 30min, 45min, 60min and 90min, and immediately introducing with PTFE needle filter membrane with pore diameter of 0.45 μmPerforming solid-liquid separation, measuring light absorption of the obtained solution at 554nm with ultraviolet-visible spectrophotometer, determining dye pollutant concentration and plotting (C/C) 0 ) -t-curve. The invention maps (C/C) to 0 ) The process of the-t curve is not particularly limited, and may be performed according to a process well known in the art.
The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
Dissolving 200mg of chitosan in 20mL of 2% glacial acetic acid solution, and standing overnight to obtain a chitosan solution; 5mmol of Cu (NO) were weighed 3 ) 2 ·3H 2 O and 5mmol of FeSO 4 ·7H 2 Dissolving O in 10mL of ultrapure water, slowly adding the obtained iron-copper metal salt solution into the chitosan solution, stirring to uniformly mix the solution, dropwise adding the obtained mixed solution into 30mL of 1.67mol/L NaOH aqueous solution, carrying out precipitation reaction at room temperature for 60min, carrying out ultrasonic treatment on the obtained iron-copper precipitation mixed solution coated with chitosan for 10min, then putting the solution into a stainless steel reaction kettle with a polytetrafluoroethylene lining, carrying out hydrothermal reaction at 180 ℃ for 12h, centrifugally washing the obtained product until the surface of the product is neutral, and carrying out vacuum drying at 60 ℃ for 12h to obtain a modified cuprous ferrite catalyst, namely OV-CuFeO catalyst 2 @ N-CNPs or OV-CuFeO 2 @ N-CNPs-200. in the prepared modified cuprous ferrite catalyst, the load capacity of nitrogen-doped carbon nanoparticles on cuprous ferrite is 17.7%.
Example 2
This example differs from example 1 only in that: the addition amount of chitosan is 100mg, and the prepared catalyst is marked as OV-CuFeO 2 @ N-CNPs-100; in the prepared modified cuprous ferrite catalyst, the loading capacity of nitrogen-doped carbon nanoparticles on cuprous ferrite is 9.3%.
Example 3
This example differs from example 1 only in that: the addition amount of the chitosan is 400mg, and the prepared catalyst is marked as OV-CuFeO 2 @ N-CNPs-400; in the prepared modified cuprous ferrite catalyst, the loading capacity of nitrogen-doped carbon nanoparticles on cuprous ferrite is 29.8%.
Comparative example 1
This comparative example differs from example 1 in that: the chitosan solution is not added, the NaOH concentration is 3.34mol/L, other steps are completely the same as the example 1, and the prepared cuprous ferrite catalyst is marked as CuFeO 2 。
Performance testing
1) XRD test was performed on the catalysts prepared in example 1 and comparative example 1, and the phase structures thereof were analyzed, and the results are shown in fig. 1. As can be seen from FIG. 1, CuFeO 2 And OV-CuFeO 2 The @ N-CNPs exhibited similar diffraction patterns; mixing the prepared material with CuFeO 2 Standard card (see, FIG. 1, lower part JCPDS card No.75-2146 (3R-CuFeO) 2 Configuration) and JCPDS card No.79-1546 (2H-CuFeO) 2 Configuration)), the three strong peaks are 31.23 °, 35.69 ° and 40.19 °, respectively, corresponding to the (006), (012) and (104) crystal planes of the R-3m type delafossite, while OV-CuFeO is observed 2 The @ N-CNPs have 1-4 tiny peaks, which are associated with Fe 2 O 3 Corresponds to the standard card of (JCPDS cardno.72-0469), indicating the presence of a small amount of Fe in the catalyst prepared in example 1 2 O 3 By-products, but no characteristic peak of CuO is detected, so that an oxygen-deficient reduction environment induced by Maillard reaction can be presumed to occur in the hydrothermal process of chitosan, so that Fe 2 O 3 Generating and competing for the main phase CuFeO 2 Because the radiuses of copper ions and iron ions are similar, part of Cu atoms can replace Fe atoms to enter octahedral lattices, Cu inversion defects are generated, and a large number of oxygen vacancies are generated in main phase lattices.
2) The catalysts prepared in example 1 and comparative example 1 were subjected to raman spectroscopy and the results are shown in fig. 2. The delafossite compound has a triangular crystal system symmetrical structure, and 12 normal species are generated in each primitive cell in point group and space group crystal formsVibration mode in which only A 1g And E g For Raman-active vibrational mode, A 1g Mode represents vibration of Cu-O bond in c-axis direction, E g The mode indicates its vibration in the a-axis direction. A in Raman Spectroscopy 1g The peak was strongest, indicating that most of the Cu-O bonds are aligned along the c-axis. As can be seen from FIG. 2, CuFeO 2 At 342cm -1 And 693cm -1 Each is provided with E g Mode Raman peaks and A 1g Modal raman peaks. The Raman spectrum is very sensitive to the defects of the sample, and OV-CuFeO is observed 2 E of @ N-CNPs g Peak compared to CuFeO 2 Moved by about 15cm in the high frequency direction -1 And A is 1g The peak is shifted by about 15cm toward the low frequency -1 . Since the Raman mode frequency is inversely proportional to the length of the binding bond, E g The Raman peak shifts to high frequency to show CuFeO 2 The lattice expands due to FeO 6 Octahedron of Fe 3+ Is filled with Cu 2+ Instead, a large number of oxygen vacancies are formed in order to maintain the charge balance of the material itself.
3) The oxygen vacancy contents of the surfaces of the catalysts prepared in example 1 and comparative example 1 were analyzed using the solid EPR technique, and the results are shown in fig. 3. FIG. 3 is CuFeO 2 And OV-CuFeO 2 EPR spectrogram of @ N-CNPs. As can be seen from FIG. 3, CuFeO 2 And CuFeO 2 The @ N-CNPs all showed a sharp EPR signal at g ═ 2.003, indicating that there were single electron-bound oxygen vacancies in the material bulk phase, the signal being derived from CuFeO 2 Is empty. Compared with pure CuFeO 2 、OV-CuFeO 2 The EPR signal at 2.003 where g is significantly enhanced in @ N-CNPs, which directly indicates OV-CuFeO 2 The @ N-CNPs contain more oxygen vacancies.
Application example 1
Rhodamine B (RhB) is used as a simulated pollutant molecule, the Fenton-like catalytic degradation capability of the modified cuprous ferrite catalyst is evaluated, and the specific method comprises the following steps: respectively at a concentration of 10 mg. L in 50mL -1 50mg of the cuprous ferrite catalyst prepared in example 1 and comparative example 1 was added to the rhodamine B dye solution, the pH was not adjusted (i.e., pH 6.8), and the resulting suspension was suspendedUltrasonically dispersing the solution in dark for 2min, then placing the beaker on a magnetic stirrer for stirring, and adding 255uL of 30% H by mass 2 O 2 Starting catalytic reaction and timing; sampling when the catalytic reaction is carried out for 0min, 10min, 20min, 30min, 45min, 60min and 90min, immediately carrying out solid-liquid separation by using a needle filter membrane made of PTFE material with the pore diameter of 0.45 mu m after each sampling, measuring the light absorption of the obtained solution at 554nm by using an ultraviolet visible spectrophotometer, determining the dye pollutant concentration and drawing (C/C) 0 ) T-curve, while using as a comparison the catalyst prepared in example 1 or in comparative example 1 without addition, and the catalyst prepared in example 1 and in comparative example 1 without addition of H 2 O 2 For comparison, the results are shown in FIG. 4.
As shown in FIG. 4, only CuFeO is present 2 And OV-CuFeO 2 In the presence of the @ N-CNPs, the adsorption removal rate of rhodamine B is only 6.7 percent and 11.1 percent. In the presence of only H 2 O 2 Then, the removal rate of rhodamine B was 1.5%. In the case of CuFeO 2 Or OV-CuFeO 2 @ N-CNPs and H 2 O 2 When the rhodamine B catalyst exists, the removal efficiency of the rhodamine B is obviously improved, which shows that the degradation of pollutants is realized mainly by catalyzing hydrogen peroxide to generate active oxygen by the prepared catalyst. And OV-CuFeO 2 Comparative example of @ N-CNPs with CuFeO 2 The catalytic degradation rate of RhB within 90min is improved from 57.0% to 100%, which shows that OV-CuFeO obtained after modification in example 1 2 The catalytic activity of the @ N-CNPs is higher.
Catalyst stability test
In the application example 1, after the modified cuprous ferrite catalyst prepared in the example 1 is used for catalytic reaction for 90min, the reaction solution is removed by centrifugation, washed by deionized water and dried, the next catalytic reaction is continued, the process is circulated for 5 times, and the degradation rate of rhodamine B after each reaction is measured, and the result is shown in FIG. 5. As can be seen from the rhodamine B degradation curve of 5-cycle experiments in FIG. 5, the degradation rate of rhodamine B can be kept above 98% after 3 cycles, and can still reach 88% after 5 cycles, which indicates that the degradation reaction process has little influence on the properties of the catalyst, and the catalyst Cu isFeO 2 The @ N-CNPs have good stability and can be recycled.
Application example 2
According to the method of application example 1, the cuprous ferrite catalyst prepared in example 2 and example 3 is used for degrading rhodamine B, and 255uL of H with the mass fraction of 30% is added into a rhodamine B dye solution 2 O 2 Determining the concentration of rhodamine B dye pollutant and drawing (C/C) 0 ) T-plot of OV-CuFeO prepared in example 1 2 @ N-CNPs-200 and CuFeO prepared in comparative example 1 2 The results are also plotted in FIG. 6. As can be seen from FIG. 6, CuFeO in comparison with comparative example 1 2 Compared with the prior art, the modified cuprous ferrite catalyst prepared by the invention has a more excellent degradation effect on rhodamine B.
Safety test
In addition, because copper is a heavy metal and the concentration is too high, the copper is harmful to the health of human bodies, so that the control of the concentration of copper ions in a system after catalytic reaction is very important.
The reaction solution obtained in application example 1 after the catalytic reaction for 90min using the catalyst prepared in example 1 was collected and passed through a 0.22um syringe filter, and the leaching concentration of copper ions was measured by ICP-MS, and it was found that the leaching concentration of copper ions was 0.79mg/L, which was much lower than the eu directive (<2.0mg/L) and the us regulation (<1.3mg/L), and the low concentration of copper ions did not affect the heterogeneous catalytic reaction.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims (7)

1. The preparation method of the modified cuprous ferrite catalyst is characterized by comprising the following steps of:
mixing a chitosan solution and an iron-copper metal salt solution, dripping the obtained mixed solution into alkali, and carrying out precipitation reaction to obtain an iron-copper precipitation mixed solution coated with chitosan;
carrying out hydrothermal reaction on the iron-copper precipitate mixed solution coated with chitosan, and drying to obtain a modified cuprous ferrite catalyst;
the dosage ratio of copper salt and iron salt in the chitosan solution and the iron-copper metal salt solution is (100-400) mg:5mmol:5 mmol;
the alkali is a sodium hydroxide aqueous solution, and the molar ratio of sodium hydroxide in the sodium hydroxide aqueous solution to copper salt in the iron-copper metal salt solution is (0.04-0.1): 5;
the temperature of the hydrothermal reaction is 160-200 ℃, and the time is 10-15 h.
2. The method according to claim 1, wherein the chitosan solution is prepared by dissolving chitosan in glacial acetic acid to obtain a chitosan solution.
3. The preparation method according to claim 2, wherein the mass concentration of the glacial acetic acid solution is 2%, and the dosage ratio of the chitosan to the glacial acetic acid solution is (100-400) mg: 20 mL.
4. The preparation method according to claim 1, wherein the drying temperature is 50-80 ℃ and the drying time is 6-12 h.
5. The modified cuprous ferrite catalyst prepared by the preparation method of any one of claims 1 to 4, comprising cuprous ferrite and nitrogen-doped carbon nanoparticles loaded on the surface of the cuprous ferrite.
6. The modified cuprous ferrite catalyst of claim 5, wherein the loading amount of the nitrogen-doped carbon nanoparticles on the cuprous ferrite is 9-30% by mass.
7. Use of the modified cuprous ferrite catalyst of claim 5 or 6 to catalyze the degradation of contaminants by hydrogen peroxide.
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