CN117753460A - Nitrogen-enriched carbon hybrid of high-selectivity singlet oxygen production system, construction method thereof and pollutant degradation application - Google Patents
Nitrogen-enriched carbon hybrid of high-selectivity singlet oxygen production system, construction method thereof and pollutant degradation application Download PDFInfo
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- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 56
- 229910052799 carbon Inorganic materials 0.000 title claims abstract description 56
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 title claims abstract description 46
- 230000015556 catabolic process Effects 0.000 title claims abstract description 29
- 238000006731 degradation reaction Methods 0.000 title claims abstract description 29
- 229910052757 nitrogen Inorganic materials 0.000 title claims abstract description 23
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 title claims abstract description 10
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- 125000002057 carboxymethyl group Chemical group [H]OC(=O)C([H])([H])[*] 0.000 claims description 2
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- 238000009777 vacuum freeze-drying Methods 0.000 claims 1
- 230000004913 activation Effects 0.000 abstract description 18
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- 229960002180 tetracycline Drugs 0.000 abstract description 14
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- 150000003522 tetracyclines Chemical class 0.000 abstract description 8
- JRKICGRDRMAZLK-UHFFFAOYSA-L peroxydisulfate Chemical compound [O-]S(=O)(=O)OOS([O-])(=O)=O JRKICGRDRMAZLK-UHFFFAOYSA-L 0.000 abstract description 7
- 239000000463 material Substances 0.000 abstract description 5
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- 238000007254 oxidation reaction Methods 0.000 abstract description 5
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- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 abstract description 3
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- OFVLGDICTFRJMM-WESIUVDSSA-N tetracycline Chemical compound C1=CC=C2[C@](O)(C)[C@H]3C[C@H]4[C@H](N(C)C)C(O)=C(C(N)=O)C(=O)[C@@]4(O)C(O)=C3C(=O)C2=C1O OFVLGDICTFRJMM-WESIUVDSSA-N 0.000 description 6
- 238000001514 detection method Methods 0.000 description 5
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- AZQWKYJCGOJGHM-UHFFFAOYSA-N 1,4-benzoquinone Chemical compound O=C1C=CC(=O)C=C1 AZQWKYJCGOJGHM-UHFFFAOYSA-N 0.000 description 4
- 238000004435 EPR spectroscopy Methods 0.000 description 4
- 229910017052 cobalt Inorganic materials 0.000 description 4
- 239000010941 cobalt Substances 0.000 description 4
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 4
- 238000002360 preparation method Methods 0.000 description 4
- HNDVDQJCIGZPNO-YFKPBYRVSA-N L-histidine Chemical compound OC(=O)[C@@H](N)CC1=CN=CN1 HNDVDQJCIGZPNO-YFKPBYRVSA-N 0.000 description 3
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Abstract
The invention discloses a construction method of a system for producing singlet oxygen with high selectivity and a pollutant degradation application. The method comprises the following steps: by self-sacrifice strategy, a novel three-dimensional porous carbon layer coated Fe is manufactured 2 O 3 ‑Fe 3 C nitrogen-enriched carbon hybrids incorporating carbon-coated Fe in situ 2 O 3 ‑Fe 3 C (. Apprxeq.17.7 nm) and has a rich oxygen vacancy. Fe (Fe) 2 O 3 ‑Fe 3 The strong coupling between C and the nitrogen doped carbon matrix promotes PDS activation. The surface defect and the interfacial charge transfer of the material rearrange the electronic structure of Fe sites, weaken the positive charge of the Fe sites, strengthen the positive charge property of C-N sites, and cooperatively guide PDS oxidation and generate the high selectivity through a non-free radical path 1 O 2 Thereby realizing high-efficiency degradation of the tetracycline. The system of the invention improves the activation of persulfate through engineering architecture and adjusting the local electron density of a plurality of active sites, and leads the persulfate to be generated with high selectivity 1 O 2 Is used for high-efficiency pollutant degradation.
Description
Technical Field
The invention relates to the field of advanced oxidation Fenton-like catalytic degradation of organic pollutants, in particular to a nitrogen-enriched carbon hybrid of a high-selectivity singlet oxygen production system, construction and pollutant degradation application thereof.
Background
Fenton-like oxidation is one of the most promising strategies for generating Reactive Oxygen Species (ROS) to treat the growing water pollution, resulting in increasingly scarce fresh water. Fenton-like systems based on persulfates, using persulfates (PDS, S 2 O 8 2- ) Or persulfate (PMS, HSO) 5 - ) As oxidizing agent, by sulfate radical (SO 4 ·- ) Hydroxyl radical (. OH) and singlet oxygen [ ] 1 O 2 ) And degrading almost all organic pollutants with high efficiency. PDS is easier to transport and lower in cost (PMS $2.2/kg, PDS $ 0.74/kg) than PMS, making it a potential choice for degradation of difficult-to-degrade contaminants. PDS, however, possess symmetrical peroxide linkages ([ SO ] 3 -O-O-SO 3 ] 2- ) It is more difficult to activate than PMS. Therefore, it is very urgent to develop an advanced catalyst having an excellent PDS activation function. Transition metals and their oxides have been used as heterogeneous catalysts for PDS activation. Among them, iron oxide has attracted attention from researchers because of its low cost and low toxicity. Development ofThe efficient iron-based catalyst is very important for PDS activation and pollutant control.
Although free radicals have a high redox potential and a wide range of reactivity, they are easy and inevitably consumed by coexisting inorganic anions and natural organics, thereby hindering degradation of target pollutants. 1 O 2 As a highly selective active species, there is a great deal of interest in the field of contaminant degradation. There is an urgent need to explore highly selective production 1 O 2 Is a catalyst and a strategy for the same. The adsorption structure of PDS on the catalyst surface can regulate the activation path of PDS. Thus, modification of the electronic structure of the metal active site by metal-carrier interactions is achieved 1 O 2 An effective strategy for high selectivity generation. Carbonaceous materials have been widely used in various fields due to structural and chemical advantages. Recently, the use of nanocarbons as PDS activators or metal component carriers has attracted increasing attention. In order to alter and improve the catalytic properties of nanocarbons, heteroatom doping has a unique advantage in improving catalytic activity. Among the doped atoms, the N atom is promising, which can not only achieve high loads due to similar atomic radii, but also alter the local charge redistribution resulting from different electronegativity. Therefore, constructing the metal oxide/N-doped carbon hybrid material is efficient in achieving PDS activation 1 O 2 The generation offers one possibility.
Disclosure of Invention
The invention aims to synthesize the three-dimensional nitrogen-doped carbon-loaded carbon-coated Fe with strong interface coupling effect, aiming at solving the problems of low pollutant degradation efficiency, poor stability and anti-interference performance and the like caused by low activity and poor selectivity of activated persulfate of a high-grade oxidation material in the prior art 2 O 3 -Fe 3 C nanoparticle composite (Fe) 2 O 3 -Fe 3 C@NC), a system for producing singlet oxygen with high selectivity is provided, and the system is applied to pollutant degradation application. The metal sites are wrapped by the carbon layer, so that metal loss is effectively inhibited, and catalytic stability is improved. Furthermore, singlet oxygen as a living speciesThe system has good anti-interference performance on inorganic anions and different water environments.
A nitrogen-enriched carbon hybrid of a high selectivity singlet oxygen-generating system, the nitrogen-enriched carbon hybrid comprising a support and a load supported on the support; the carrier comprises a three-dimensional porous nitrogen-doped carbon material; the support includes metal nanoparticles surrounded by a carbon layer.
Preferably, the carbon-coated metal nanoparticle comprises Fe 2 O 3 -Fe 3 And C nano particles.
Preferably, the particle size of the iron nanoparticle coated with the carbon layer comprises 15-25 nm.
The construction method of the nitrogen-enriched carbon hybrid of the high-selectivity singlet oxygen production system comprises the following steps:
A. immersing chitosan aqueous solution into an acid agent for crosslinking to form hydrogel;
B. soaking the hydrogel in ferric salt solution for complexing to form Fe-hydrogel;
C. drying the Fe-hydrogel to obtain an aerogel precursor;
D. and pyrolyzing the aerogel precursor to obtain the nitrogen-enriched carbon hybrid.
By self-sacrifice strategy, a novel three-dimensional porous carbon layer coated Fe is manufactured 2 O 3 -Fe 3 C nitrogen-enriched carbon hybrids incorporating carbon-coated Fe in situ 2 O 3 -Fe 3 C (. Apprxeq.17.7 nm) and has a rich oxygen vacancy. Fe (Fe) 2 O 3 -Fe 3 The strong coupling between C and the nitrogen doped carbon matrix promotes PDS activation. The surface defect and the interfacial charge transfer of the material rearrange the electronic structure of Fe sites, weaken the positive charge of the Fe sites, strengthen the positive charge property of C-N sites, and cooperatively guide PDS oxidation and generate the high selectivity through a non-free radical path 1 O 2 Thereby realizing high-efficiency degradation of the tetracycline. The system of the invention enhances the activation of persulfates and enables them to be achieved by engineering the architecture and modulating the local electron density of the multiple active sitesHighly selective production 1 O 2 Is used for high-efficiency pollutant degradation.
Preferably, in step a, the acid agent comprises acetic acid; in step B, the iron salt solution comprises Fe (CH) 3 COO) 2 An aqueous solution; in step C, the drying includes low temperature drying; in step D, the pyrolyzing includes calcining.
Preferably, in step a, the concentration of the aqueous chitosan solution comprises 6wt%; in step B, the concentration of the iron salt solution comprises 0.1M;
preferably, in the step a, the chitosan aqueous solution includes carboxymethyl chitosan aqueous solution; the specific operation of the step C comprises the following steps: cleaning the Fe-hydrogel, soaking the Fe-hydrogel in an alcohol agent, and drying the Fe-hydrogel to obtain the aerogel precursor; the specific operation of the step D comprises the following steps: and placing the aerogel precursor in a calciner, and calcining and pyrolyzing the aerogel precursor at 850-1000 ℃ in an inert atmosphere to obtain the nitrogen-enriched carbon hybrid.
In step A, B, C, the acid agent, the iron salt solution and the alcohol agent are immersed mainly, and the amount of the acid agent, the iron salt solution and the alcohol agent is not particularly limited, and may be slightly excessive to accelerate the reaction rate and make the reaction more thorough.
Preferably, in step a, the time of crosslinking includes 15min; in step B, the complexing time comprises 3h; in the step C, the time for soaking the Fe-hydrogel in an alcohol agent after washing comprises 24 hours; the drying time includes one day; in step D, the temperature of the calcination pyrolysis comprises 900 ℃; the time of calcination pyrolysis comprises 1h.
Experiments show that when the temperature reaches 850-1000 ℃ in the calcining pyrolysis process, the carbon layer wraps Fe 2 O 3 -Fe 3 C nano particle structure, and the carbon layer is more uniformly wrapped when the temperature is controlled at 900 ℃, so that the catalysis effect is best.
Preferably, in step C, the Fe-hydrogel is washed with deionized water; the alcohol agent comprises tertiary butanol; in step D, the calciner comprises a tubular calciner; the inert atmosphere comprises an argon atmosphere.
The application of the nitrogen-enriched carbon hybrid of the high-selectivity singlet oxygen-producing system in pollutant degradation.
The invention comprises the following contents:
1. three-dimensional nitrogen-doped carbon-loaded carbon-coated Fe 2 O 3 -Fe 3 Preparation of C nanoparticle composite
Chitosan is used as a carbon and nitrogen source, is prepared into a water solution with a certain concentration, and forms hydrogel through self-crosslinking under an acidic condition. And then carrying out coordination complexing on the metal-chitosan aerogel and Fe ions to form a metal-hydrogel complex, and drying at low temperature to obtain the metal-chitosan aerogel. Calcining the aerogel at high temperature to obtain three-dimensional nitrogen-doped carbon-loaded carbon-coated Fe 2 O 3 -Fe 3 C nanoparticle composites.
2. PDS activation of composite materials 1 O 2 Detection and analysis of active species.
3. And testing the pollutant degradation efficiency, stability and anti-interference capability of the composite material.
A certain amount of the pollutant solution was taken in a beaker, and a catalyst and potassium Peroxodisulfate (PDS) were added to test PDS activation and pollutant degradation effects. Through capture experiments and electron paramagnetic resonance EPR test 1 O 2 Contribution. 1 O 2 Possible generation paths:
compared with the prior art, the implementation of the invention has the following beneficial effects:
(1) Taking a three-dimensional porous nitrogen-doped carbon material as a carrier, and loading carbon-coated Fe on the surface of the carrier 2 O 3 -Fe 3 C nano particles are used for preparing the composite catalyst. The large surface area support can both disperse and expose the active sites and act as an electron transport framework. At the same time Fe 3 C can be used as a PDS adsorption site to cooperatively promote the activation efficiency of PDS on the surface of the catalyst. In addition, the metal sites are wrapped by the carbon layer, so that metal loss is effectively inhibited. The catalyst shows better PDS catalytic activity and stability.
(2) The charge density between the carrier and the metal active site is rearranged through the interface interaction of the material, so that the PDS activation path is changed, and active oxygen generated by activating PDS by the composite material is mainly 1 O 2 Thereby promoting the efficient degradation of pollutants and showing strong anti-interference capability to inorganic anions and water environments.
Drawings
FIG. 1 is a structural representation of a catalyst, wherein FIG. 1a is Fe 2 O 3 -Fe 3 XRD pattern of C@NC, FIG. 1b is Fe 2 O 3 -Fe 3 TEM image of C@NC, FIG. 1c shows N for different samples 2 Adsorption-desorption isotherms and pore size distribution, FIG. 1d shows Fe 2 O 3 -Fe 3 The performance test chart of the tetracycline degradation by activating PDS with the catalyst of C@NC and CoOx-Co@NC;
FIG. 2 is NC and Fe 2 O 3 -Fe 3 XPS fine spectrum N1s contrast graph of C@NC;
FIG. 3 is an XRD pattern and TEM pattern of CoOx-Co@NC;
FIG. 4 is a diagram of PDS activation 1 O 2 A detection analysis chart of the active species; wherein FIG. 4a is a plot of PDS consumption versus various catalysts, and FIG. 4b is 1 O 2 FIG. 4c is a capture experimental plot;
FIG. 5 is a graph of contaminant degradation activity, stability, and tamper resistance; fig. 5a is a comparative experiment diagram using different catalysts, fig. 5b is a cyclic stability test diagram, fig. 5c is a comparative diagram of the effects of different inorganic ions, and fig. 5d is a comparative diagram of the effects of different aqueous environments.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings, for the purpose of making the objects, technical solutions and advantages of the present invention more apparent.
Example 1
Step 1: preparation of the catalyst:
a. preparation of metal-chitosan aerogel: a6 wt% aqueous chitosan solution (5 g) was placed in a petri dish at room temperature, which was immersed in acetic acid to crosslink for 15min to form a hydrogel. Then soaking it in Fe (CH) 3 COO) 2 In aqueous solution (0.1M), complexing for 3h, washing with deionized water, soaking in tertiary butanol for 24h, and drying Fe-hydrogel at low temperature for one day to obtain Fe (II) -chitosan coordinated aerogel.
b. Three-dimensional nitrogen-doped carbon-loaded carbon-coated Fe 2 O 3 -Fe 3 C, preparing a nanoparticle composite material: placing the aerogel precursor in a tube furnace, calcining for 1h at 900 ℃ in an argon atmosphere, and converting the Fe (II) -chitosan coordinated aerogel into 3D nitrogen-doped carbon-loaded carbon-coated Fe in situ 2 O 3 -Fe 3 The structural characterization of the C nanoparticle composite and the catalyst is shown in fig. 1. XRD patterns showed the iron species as Fe 2 O 3 And Fe (Fe) 3 C, and these nanoparticles are encapsulated by a carbon layer and uniformly supported in a three-dimensional network carbon material framework (fig. 1 b). FIG. 1c shows that the NC catalyst has a specific surface area of 107.96m 2 /g, and after loading of Fe metal, fe catalyst 2 O 3 -Fe 3 The specific surface area of C@NC is increased to 348.11m 2 And/g, the metal oxide has strong coupling effect with the carbon substrate, so that the specific surface area of the metal oxide is greatly improved. FIG. 2 is NC and Fe 2 O 3 -Fe 3 XPS N1s fine spectrum contrast plot of c@nc. Is identical to the originalCompared with the starting NC, fe 2 O 3 -Fe 3 The binding energy of the C@NC peak was significantly shifted to higher binding energy, indicating Fe 2 O 3 -Fe 3 C causes a change in the electronic environment of the N-doped C matrix. This phenomenon also illustrates Fe 2 O 3 -Fe 3 There is a strong interaction between C and NC, inducing rearrangement of electrons.
In the early stage experiment, cobalt is used as a metal precursor, the calcining temperature is increased to 900 ℃, other operations are unchanged, the existence forms of cobalt are represented by CoOx and Co simple substances through XRD and TEM (figure 3) characterization, the nano particles are directly embedded into a three-dimensional carbon network, and no obvious carbon layer wrapping structure is found on the surface. Different metal elements are adopted, and the catalyst structure obtained by the same preparation method has obvious difference. The iron-based catalyst obtains 3D nitrogen doped carbon loaded carbon coated Fe 2 O 3 -Fe 3 The C nanoparticle composite material and the carbon layer are wrapped, so that metal loss can be effectively inhibited, and the catalytic stability and environmental friendliness are maintained. At the same time Fe 3 C can be used as an adsorption site of PDS to improve the activity of the catalyst. Through performance tests, it was found that the iron-based catalyst (Fe 2 O 3 -Fe 3 C@NC) activated PDS has better tetracycline degradation effect than cobalt-based catalyst (CoOx-Co@NC).
Step 2: PDS activation 1 O 2 Detection and analysis of active species
PDS activation detection: PDS concentration was measured by high concentration iodometry as follows: 2.5mL of the suspension was aspirated over the set time interval and immediately filtered to remove catalyst, 0.1mL of sample was taken with NaHCO 3 (0.02 g), KI (0.415 g) and 4.9mL deionized water were mixed and reacted for 20min, and the residual concentration of PDS was determined at 400nm using an ultraviolet-visible spectrophotometer.
1 O 2 Active species capture assay: weighing 0.2g/L of catalyst, 0.2g/L of PDS, preparing 20mg/L of Tetracycline (TC) solution, taking 40mL of 20mg/L of TC solution in a 150mL beaker, adding a capturing agent with a certain concentration, stirring uniformly, and then adding the catalyst and potassium Persulfate (PDS) for catalytic degradation test. Aspirate 2.5mL of suspension over a set time interval and immediately passFiltering to remove the catalyst; the residual concentration of contaminants was determined with an ultraviolet-visible spectrophotometer at 357 nm. EPR test: the detection was performed using a Bruker EMXplus instrument with 2, 6-tetramethyl-4-piperidinol (TEMP 100 mM) as the capture reagent and the results are shown in FIG. 4.
FIG. 4a shows Fe 2 O 3 -Fe 3 C@NC catalyst activation performance ratio NC and pure Fe 2 O 3 -Fe 3 C is high, and has higher activation PDS capability. FIG. 4b shows the presence confirmed by EPR test 1 O 2 . FIG. 4c Methanol (MA) quench SO 4 ·- Quenching of O with OH, p-Benzoquinone (BQ) 2 ·- Tertiary Butanol (TBA) quench-OH; quenching of L-histidine (L-his) 1 O 2 The method comprises the steps of carrying out a first treatment on the surface of the The Phenylmethylsulfone (PMSO) quenches the high-valence iron, and the main effect is found by comparison 1 O 2 Next is O 2 ·- 。
Step 3: pollutant degradation activity, stability and anti-interference test
Performance test: weigh 0.2g/L catalyst, 0.2g/L PDS, prepare 20mg/L Tetracycline (TC) solution, take 40mL 20mg/L TC solution in 150mL beaker, add catalyst and potassium Persulfate (PDS) at the same time to carry out the catalytic degradation test. Sucking 2.5mL of the suspension in a set time interval and immediately filtering to remove the catalyst; the residual concentration of contaminants was determined with an ultraviolet-visible spectrophotometer at 357 nm. Testing the performance of the alloy;
stability test: filtering the catalyst after the reaction is finished, supplementing the catalyst in parallel experiments, washing for a plurality of times by using distilled water, then placing the catalyst in an oven for drying completely at 60 ℃, annealing for 30min at 300 ℃, and continuing the next experiment, and repeating four times; ICP test is carried out through digestion, and the metal leaching rate of the catalyst is calculated.
Interference immunity test: firstly, dissolving different anionic reagents in deionized water, uniformly mixing, and adding a catalyst and PDS to perform catalyst degradation test; preparing 20mg/L tetracycline solution from tap water, reservoir and lake water respectively, adding catalyst and PDS for catalytic degradation test, and testing performance of the steps.
The above-mentioned knotThe results are listed in fig. 5 [ condition: fe (Fe) 2 O 3 -Fe 3 C@NC＝0.2g/L，PDS＝0.2g/L，TC＝20mg/L，pH＝6]。
Comparative experiments in FIG. 5a found PDS and Fe alone 2 O 3 -Fe 3 C has substantially no ability to activate PDS, fe obtained after combining substrate NC with metallic Fe 2 O 3 -Fe 3 The performance of the C@NC catalyst is greatly improved, the degradation effect reaches 92%, and the Fe is indicated 2 O 3 -Fe 3 The C@NC catalyst has better catalytic activity.
FIG. 5b shows that after 5 cycles, the catalyst removal efficiency for TC can still reach 87%, which can be explained by Fe 2 O 3 -Fe 3 The C@NC has excellent stability. And the leaching rate of the metal after 5 times of circulation of the catalyst is 13%, and the leaching rate of the cobalt-based catalyst (CoOx-Co@NC) after three times of circulation is as high as 79.3%. This conclusion shows that the carbon layer encapsulation structure can significantly inhibit metal loss.
FIGS. 5c and d show that different anions and different water systems are specific to Fe 2 O 3 -Fe 3 The degradation of tetracycline by the C@NC/PDS system is not greatly affected, wherein 1 O 2 Plays a major role rather than free radical 1 O 2 Is not easy to be influenced by inorganic ions and natural organic matters, which indicates that Fe 2 O 3 -Fe 3 The C@NC/PDS system has strong anti-interference performance and wide application range.
The foregoing disclosure is merely illustrative of the preferred embodiments of the present invention and is not intended to limit the scope of the claims herein, as equivalent changes may be made in the claims herein without departing from the scope of the invention.
Claims (10)
1. A nitrogen-enriched carbon hybrid of a high selectivity singlet oxygen-generating system, wherein the nitrogen-enriched carbon hybrid comprises a support and a load supported on the support; the carrier comprises a three-dimensional porous nitrogen-doped carbon material; the support includes metal nanoparticles surrounded by a carbon layer.
2. The height according to claim 1A nitrogen-enriched carbon hybrid for selectively producing a singlet oxygen system, characterized in that the metal nanoparticles coated with a carbon layer comprise Fe 2 O 3 -Fe 3 And C nano particles.
3. The nitrogen-enriched carbon hybrid of the high selectivity singlet oxygen-generating system according to claim 1, wherein the particle size of the iron nanoparticles encapsulated by the carbon layer comprises 15 to 25nm.
4. A method of constructing a nitrogen-enriched carbon hybrid of a high selectivity singlet oxygen-generating system according to claim 1, comprising the steps of:
A. immersing chitosan aqueous solution into an acid agent for crosslinking to form hydrogel;
B. soaking the hydrogel in ferric salt solution for complexing to form Fe-hydrogel;
C. drying the Fe-hydrogel to obtain an aerogel precursor;
D. and pyrolyzing the aerogel precursor to obtain the nitrogen-enriched carbon hybrid.
5. The method of claim 4, wherein in step a, the acid agent comprises acetic acid; in step B, the iron salt solution comprises Fe (CH) 3 COO) 2 An aqueous solution; in step C, the drying includes low temperature drying; in step D, the pyrolyzing includes calcining.
6. The method of claim 4, wherein in step A, the concentration of the aqueous chitosan solution comprises 6wt%; in step B, the concentration of the iron salt solution comprises 0.1M; in step C, the drying comprises vacuum freeze drying, and the temperature comprises-55 ℃.
7. The method of claim 4, wherein in step a, the aqueous chitosan solution comprises an aqueous carboxymethyl chitosan solution; the specific operation of the step C comprises the following steps: cleaning the Fe-hydrogel, soaking the Fe-hydrogel in an alcohol agent, and drying the Fe-hydrogel to obtain the aerogel precursor; the specific operation of the step D comprises the following steps: and placing the aerogel precursor in a calciner, and calcining and pyrolyzing the aerogel precursor at 850-1000 ℃ in an inert atmosphere to obtain the nitrogen-enriched carbon hybrid.
8. The method of claim 7, wherein in step a, the time of crosslinking comprises 15 minutes; in step B, the complexing time comprises 3h; in the step C, the time for soaking the Fe-hydrogel in an alcohol agent after washing comprises 24 hours; the drying time includes one day; in step D, the temperature of the calcination pyrolysis comprises 900 ℃; the time of calcination pyrolysis comprises 1h.
9. The method of claim 7, wherein in step C, deionized water is used to wash the Fe-hydrogel; the alcohol agent comprises tertiary butanol; in step D, the calciner comprises a tubular calciner; the inert atmosphere comprises an argon atmosphere.
10. Use of a nitrogen-enriched carbon hybrid of a highly selective singlet oxygen-generating system according to claim 1, for contaminant degradation.
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