A tubular amorphous nickel-doped carbon nitride material and its preparation method and application

Abstract

The invention relates to the technical field of catalyst preparation, and in particular to a tubular amorphous nickel-doped carbon nitride material and a preparation method and application thereof. The invention comprises the following steps: using melamine and cyanuric acid as carbon nitride precursors, mixing and stirring to obtain an emulsion, using a soluble nickel salt as a nickel source, adding a soluble nickel salt and an auxiliary agent to the emulsion, mixing and stirring to obtain a mixed sample, drying and grinding the mixed sample to obtain a powder, and heating the powder to obtain a tubular amorphous nickel-doped carbon nitride material. The invention utilizes the advantage that pyridine nitrogen with abundant lone pair electrons in carbon nitride precursor molecules can be used as a transition metal anchoring site, and prepares a tubular nickel-doped carbon nitride catalyst by a simple thermal polycondensation method, and constructs an efficient Fenton-like reaction system with peroxymonosulfate.

Description

Technical Field

[0001] The invention relates to the technical field of catalyst preparation, and in particular to a tubular amorphous nickel-doped carbon nitride material and a preparation method and application thereof. Background Art

[0002] Phenol is a white crystal with a special smell at room temperature and pressure. It was first discovered in coal tar. As an important industrial raw material, phenol is widely used in production, and the demand is increasing. Phenol has low biodegradability and will cause serious and lasting pollution when discharged into the environment. Therefore, phenol wastewater is listed as a priority degradation pollutant. At present, advanced oxidation is an effective and low-cost wastewater treatment method. Using a catalyst as an inducer to activate permonosulfate to produce free radicals and non-radical active substances, and using this active substance to efficiently degrade phenol is the most widely used and convenient method in advanced oxidation treatment methods in recent years.

[0003] Fenton oxidation technology is the main treatment technology for refractory organic wastewater. However, the traditional iron-based homogeneous Fenton technology has many shortcomings, such as (1) the reaction pH range is narrow, and it can only achieve good removal effect on pollutants in acidic solutions of 2.00-4.00; (2) the catalyst cannot be recycled, and the reaction produces a large amount of agglomerated iron sludge, which causes secondary pollution to the environment; (3) the free radical donor is hydrogen peroxide, which is expensive and has safety hazards in storage. In order to overcome these shortcomings, heterogeneous Fenton oxidation technology came into being. It has a wide pH operating range, the catalyst is easy to recycle and reuse, and can catalyze a variety of free donors such as hydrogen peroxide, permonosulfate, and peroxydisulfate. At present, the development of heterogeneous Fenton oxidation technology mainly includes two aspects: one is the preparation of heterogeneous catalysts; the other is to broaden the free radical donors. Among them, the preparation of efficient and stable catalysts is the key and difficulty of heterogeneous Fenton oxidation technology. Supported heterogeneous catalysts inherit the advantages of homogeneous and heterogeneous catalysts, bridge the gap between the two, and become a very attractive material in the field of heterogeneous Fenton environmental governance.

[0004] The development of heterogeneous catalysts in Fenton-like reactions has made great progress, and some studies have also achieved good results. However, there are still problems such as loss of active components and catalyst deactivation; and metal particles usually have uneven sizes and irregular shapes. Each metal particle may have multiple active sites with different properties, which will reduce the selectivity of the product; in addition, only the surface metal atoms play a catalytic role in the reaction as active sites, and the effective utilization rate of the metal is low. Therefore, the size of metal nanoparticles becomes an important factor in determining the reaction activity and selectivity of supported metal catalysts. However, the metal loading of heterogeneous catalysts is low, and it is very easy to agglomerate and couple to form large clusters during the reaction, which limits the overall performance and practical application of the catalyst. Therefore, how to design and prepare heterogeneous catalysts with high metal loading and good stability is a difficult problem that needs to be solved in the field of Fenton-like oxidation technology.

[0005] Under normal conditions, carbon nitride obtained by high-temperature thermal polycondensation of carbon-nitrogen precursors such as urea, melamine, and dicyandiamide is mostly a densely stacked block material. The tight stacking effect hinders the reaction active sites of the carbon nitride material. Commonly used transition metal doped carbon nitride is also to first prepare the carbon nitride material, and then load the transition metal on the surface of the carbon nitride by deposition and other methods. This not only has a complex preparation process, but also has low catalytic efficiency and poor stability. Summary of the invention

[0006] In view of the deficiencies of the above-mentioned prior art, the object of the present invention is to provide a tubular amorphous nickel-doped carbon nitride material and a preparation method and application thereof. The present invention utilizes the advantage that pyridine nitrogen with abundant lone pair electrons in the carbon nitride precursor molecule can be used as a transition metal anchor, and prepares a tubular nickel-doped carbon nitride catalyst by a simple thermal condensation method, and constructs an efficient Fenton-like reaction system with peroxymonosulfate.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0008] A method for preparing a tubular amorphous nickel-doped carbon nitride material comprises the following steps:

[0009] Melamine and cyanuric acid are used as carbon nitride precursors, and are mixed and stirred to obtain an emulsion;

[0010] A soluble nickel salt is used as a nickel source, and a soluble nickel salt and an auxiliary agent are added to the emulsion, wherein the nickel salt is soluble in water, and melamine is slightly soluble in water. The two are mixed without reaction, and the layers are separated after standing, wherein the lower layer is melamine, and the upper layer is a nickel salt aqueous solution. After the auxiliary agent is added, it plays a bridging role, and melamine and the nickel salt are no longer separated, and a uniform light green slurry is formed. The nickel salt and melamine are combined and evenly dispersed, mixed and stirred to obtain a mixed sample, and the mixed sample is dried and ground to obtain a powder;

[0011] The powder is subjected to a heating treatment to cause a polycondensation reaction to obtain a tubular amorphous nickel-doped carbon nitride material. Melamine removes ammonia and undergoes polymerization. The bridging nickel atoms combine with N-atoms in the polycondensation reaction to form a coordination bond for stable existence. The polycondensation reaction can make the nickel atoms more solid. After melamine is polycondensed into carbon nitride, it can synergize with the nickel atoms to improve the catalytic efficiency of the catalyst.

[0012] In a preferred embodiment of the present invention, the nickel source is one of nickel nitrate hexahydrate, nickel chloride hexahydrate, and nickel sulfate.

[0013] In a preferred embodiment of the present invention, the auxiliary agent is one of dimethylene sulfoxide, 2-methylimidazole and ethanol.

[0014] In a preferred embodiment of the present invention, the heating treatment temperature is 450° C. to 600° C., and the heating treatment time is 2 h to 6 h.

[0015] In a preferred embodiment of the present invention, the mass fraction of the soluble nickel salt in melamine is 5% to 30%.

[0016] In a preferred embodiment of the present invention, the molar ratio of the two raw materials in the carbon nitride precursor is 1-5:1-5.

[0017] In a preferred embodiment of the present invention, the molar ratio of the auxiliary agent to the soluble nickel salt is 1:10-80.

[0018] Another object of the present invention is to provide a tubular amorphous nickel-doped carbon nitride material prepared by any of the preparation methods described above, wherein the nickel-doped carbon nitride material consists of a tubular structure and has a size of micrometer level.

[0019] The third object of the present invention is to provide a Fenton-like reaction system, which is constructed by the tubular non-static nickel-doped carbon nitride material prepared by the present invention and peroxymonosulfate.

[0020] In a preferred embodiment of the present invention, the Fenton-like reaction system is used to degrade phenol wastewater.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. The present invention uses melamine and cyanuric acid as carbon nitride precursors, mixes them to obtain an emulsion, adds a soluble nickel salt and an auxiliary agent to the emulsion, and utilizes the advantage that the pyridine nitrogen with abundant lone pair electrons in the carbon nitride precursor molecule can be used as a transition metal anchor. A tubular nickel-doped carbon nitride catalyst is prepared by a simple thermal polycondensation method. Melamine removes ammonia and polymerizes. The bridged nickel atoms combine with the N-atoms in the polycondensation reaction to form a coordination bond to exist stably. The polycondensation reaction can make the nickel atoms more solid. After melamine is polycondensed into carbon nitride, it can be The nickel atoms act synergistically to improve the catalytic efficiency of the catalyst, and construct an efficient Fenton-like reaction system with peroxymonosulfate to degrade phenol wastewater. The nickel atoms in the catalyst prepared by the present invention can directly react with peroxymonosulfate to generate sulfate radicals with strong oxidizing properties. The sulfate radicals can oxidize and decompose organic matter to generate carbon dioxide and water, while the nickel atoms are reduced to a high-valent state. The catalyst carrier carbon nitride can transmit electrons to reduce the nickel atoms. The reduced nickel atoms continue to participate in oxidation, and the peroxymonosulfate generates sulfate radicals, and finally the phenol is decomposed and oxidized.

[0023] 2. The composite material prepared by the present invention has a square tubular structure. Nickel in the composite material exists stably in an amorphous form. The specific surface area is more than 10 times that of pure carbon nitride, which is much higher than the same type of transition metal-doped carbon nitride composite material. In addition, the composite material of the present invention has a high catalytic effect on peroxymonosulfate and can efficiently degrade phenol.

[0024] 3. Nickel, as a transition metal element, has good mechanical properties and ductility, is resistant to high temperatures, is insoluble in water, and has strong resistance to acid and alkali corrosion. The present invention proposes a new method for preparing tubular nickel-doped carbon nitride in view of the current status of the prior art. The product has a novel and special morphology, greatly increased reaction sites, and a Fenton-like reaction system is constructed with peroxymonosulfate to degrade phenol wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a graph showing the degradation rate results of the composite material Ni / CN prepared in Examples 1 to 4 of the present invention.

[0026] Figure 2 This is a graph showing the cycling test results of the composite material Ni / CN prepared in Example 1 of the present invention.

[0027] Figure 3 This is a surface morphology of the composite material Ni / CN prepared in Example 1 of the present invention.

[0028] Figure 4 This is a transmission electron microscope image of the composite material Ni / CN prepared in Example 1 of the present invention.

[0029] Figure 5This is a high-resolution transmission electron microscopy image of the composite material Ni / CN prepared in Example 1 of the present invention.

[0030] Figure 6 This is the surface EDS spectrum of the composite material Ni / CN prepared in Example 1 of the present invention.

[0031] Figure 7 This is the XRD spectrum of the composite material Ni / CN prepared in Example 1 of the present invention.

[0032] Figure 8 This is a summary of the specific surface area report data of the composite material Ni / CN prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0033] The following is a detailed description of the technical solutions in the embodiments of the present invention in combination with the preferred embodiments and the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] It should be noted that all professional terms used in the present invention are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention. Unless otherwise specifically stated, various raw materials, reagents, instruments and equipment used in the following embodiments of the present invention can be purchased from the market or prepared by existing methods.

[0035] Example 1

[0036] A method for preparing a single-atom nickel-doped carbon nitride composite material comprises the following steps:

[0037] (1) Take cyanuric acid and melamine in a molar mass ratio of 1:1 as carbon nitride precursors, add them into 150 mL of deionized water, stir and react for 4 hours to obtain an emulsion.

[0038] (2) adding nickel nitrate hexahydrate and an auxiliary agent 2-methylimidazole to the emulsion prepared in step (1), stirring with a magnetic stirrer for 1 hour at a speed of 200 r / min to completely mix the emulsion to obtain a mixture, wherein the molar mass ratio of the 2-methylimidazole to the nickel nitrate hexahydrate is 1:40; and the mass ratio of the nickel nitrate hexahydrate to melamine is 14%.

[0039] (3) The mixture obtained in step (2) was placed in a forced air drying oven, dried at 105° C. for 24 h, and ground into powder.

[0040] (4) The powder was transferred into an alumina crucible with a lid, and then placed in a muffle furnace. In a nitrogen atmosphere, the temperature was increased to 500° C. at a heating rate of 5° C. / min and maintained for 4 h. After natural cooling, the powder was taken out and ground to obtain a gray composite material, i.e., a tubular nickel-doped carbon nitride material, recorded as Ni / CN-14%.

[0041] Example 2

[0042] A method for preparing a single-atom nickel-doped carbon nitride composite material comprises the following steps:

[0043] (1) Take cyanuric acid and melamine in a molar mass ratio of 1:1 as carbon nitride precursors, add them into 150 mL of deionized water, stir and react for 4 hours to obtain an emulsion.

[0044] (2) Adding nickel nitrate hexahydrate and an auxiliary agent 2-methylimidazole to the emulsion prepared in step (1), stirring with a magnetic stirrer for 1 hour at a speed of 200 r / min to completely mix the mixture to obtain a mixture, wherein the molar mass ratio of the 2-methylimidazole to the nickel nitrate hexahydrate is 1:40, and the mass ratio of the nickel nitrate hexahydrate to the carbon nitride precursor is 7%.

[0045] (3) The mixture obtained in step (2) was placed in a forced air drying oven, dried at 105° C. for 24 h, and ground into powder.

[0046] (4) The powder was transferred into an alumina crucible with a lid, and then placed in a muffle furnace. In a nitrogen atmosphere, the temperature was increased to 500° C. at a heating rate of 5° C. / min and maintained for 4 h. After natural cooling, the powder was taken out and ground to obtain a gray composite material, i.e., a tubular nickel-doped carbon nitride material, recorded as Ni / CN-7%.

[0047] Example 3

[0048] A method for preparing a single-atom nickel-doped carbon nitride composite material comprises the following steps:

[0049] (1) Melamine and cyanuric acid in a molar mass ratio of 1:1 were added into 150 mL of deionized water and stirred for 4 h to obtain an emulsion.

[0050] (2) Adding nickel nitrate hexahydrate and an auxiliary agent 2-methylimidazole to the emulsion prepared in step (1), stirring with a magnetic stirrer for 1 hour at a speed of 200 r / min to completely mix the mixture to obtain a mixture, wherein the molar mass ratio of the 2-methylimidazole to the nickel nitrate hexahydrate is 1:40, and the mass ratio of the nickel nitrate hexahydrate to the carbon nitride precursor is 21%.

[0051] (3) The mixture obtained in step (2) was placed in a forced air drying oven, dried at 105° C. for 24 h, and ground into powder.

[0052] (4) The powder was transferred into an alumina crucible with a lid, and then placed in a muffle furnace. In a nitrogen atmosphere, the temperature was increased to 500° C. at a heating rate of 5° C. / min and maintained for 4 h. After natural cooling, the powder was taken out and ground to obtain a gray composite material, i.e., a tubular nickel-doped carbon nitride material, recorded as Ni / CN-21%.

[0053] Example 4

[0054] A method for preparing a single-atom nickel-doped carbon nitride composite material comprises the following steps:

[0055] (1) Take cyanuric acid and melamine in a molar mass ratio of 1:1 as carbon nitride precursors, add them into 150 mL of deionized water, stir and react for 4 hours to obtain an emulsion.

[0056] (2) Adding nickel nitrate hexahydrate and an auxiliary agent 2-methylimidazole to the emulsion prepared in step (1), stirring with a magnetic stirrer for 1 hour at a speed of 200 r / min to completely mix the mixture to obtain a mixture, wherein the molar mass ratio of the 2-methylimidazole to the nickel nitrate hexahydrate is 1:40, and the mass ratio of the nickel nitrate hexahydrate to the carbon nitride precursor is 28%.

[0057] (3) The mixture obtained in step (2) was placed in a forced air drying oven, dried at 105° C. for 24 h, and ground into powder.

[0058] (4) The powder was transferred into an alumina crucible with a lid, and then placed in a muffle furnace. In a nitrogen atmosphere, the temperature was increased to 500° C. at a heating rate of 5° C. / min and maintained for 4 h. After natural cooling, the powder was taken out and ground to obtain a gray composite material, i.e., a tubular nickel-doped carbon nitride material, recorded as Ni / CN-28%.

[0059] Example 5

[0060] A method for preparing a single-atom nickel-doped carbon nitride composite material comprises the following steps:

[0061] (1) Take cyanuric acid and melamine in a molar mass ratio of 2:5 as carbon nitride precursors, add them into 150 mL of deionized water, stir and react for 4 hours to obtain an emulsion.

[0062] (2) Adding nickel nitrate hexahydrate and an auxiliary agent 2-methylimidazole to the emulsion prepared in step (1), stirring with a magnetic stirrer for 1 hour at a speed of 200 r / min to completely mix the mixture to obtain a mixture, wherein the molar mass ratio of the 2-methylimidazole to the nickel nitrate hexahydrate is 1:10, and the mass ratio of the nickel nitrate hexahydrate to the carbon nitride precursor is 5%.

[0063] (3) The mixture obtained in step (2) was placed in a forced air drying oven, dried at 105° C. for 24 h, and ground into powder.

[0064] (4) The powder was transferred into an alumina crucible with a lid, and then placed in a muffle furnace. In a nitrogen atmosphere, the temperature was increased to 450° C. at a heating rate of 5° C. / min and maintained for 6 h. After natural cooling, the powder was taken out and ground to obtain a gray composite material, i.e., a tubular nickel-doped carbon nitride material.

[0065] Example 6

[0066] A method for preparing a single-atom nickel-doped carbon nitride composite material comprises the following steps:

[0067] (1) Take cyanuric acid and melamine in a molar mass ratio of 5:1 as carbon nitride precursors, add them into 150 mL of deionized water, stir and react for 4 hours to obtain an emulsion.

[0068] (2) Adding nickel nitrate hexahydrate and an auxiliary agent 2-methylimidazole to the emulsion prepared in step (1), stirring with a magnetic stirrer for 1 hour at a speed of 200 r / min to completely mix the mixture to obtain a mixture, wherein the molar mass ratio of the 2-methylimidazole to the nickel nitrate hexahydrate is 1:80, and the mass ratio of the nickel nitrate hexahydrate to the carbon nitride precursor is 14%.

[0069] (3) The mixture obtained in step (2) was placed in a forced air drying oven, dried at 105° C. for 24 h, and ground into powder.

[0070] (4) The powder was transferred into an alumina crucible with a lid, and then placed in a muffle furnace. In a nitrogen atmosphere, the temperature was increased to 600° C. at a heating rate of 5° C. / min and maintained for 2 h. After natural cooling, the powder was taken out and ground to obtain a gray composite material, i.e., a tubular nickel-doped carbon nitride material.

[0071] Example 7

[0072] A method for preparing a single-atom nickel-doped carbon nitride composite material comprises the following steps:

[0073] (1) Take cyanuric acid and melamine in a molar mass ratio of 1:1 as carbon nitride precursors, add them into 150 mL of deionized water, stir and react for 4 hours to obtain an emulsion.

[0074] (2) adding nickel chloride hexahydrate and an auxiliary agent, dimethyl sulfoxide, to the emulsion prepared in step (1), stirring with a magnetic stirrer for 1 hour at a speed of 200 r / min to completely mix the emulsion to obtain a mixture, wherein the molar mass ratio of dimethyl sulfoxide to nickel chloride hexahydrate is 1:40; and the mass ratio of nickel chloride hexahydrate to melamine is 14%.

[0075] (3) The mixture obtained in step (2) was placed in a forced air drying oven, dried at 105° C. for 24 h, and ground into powder.

[0076] (4) The powder was transferred into an alumina crucible with a lid, and then placed in a muffle furnace. In a nitrogen atmosphere, the temperature was increased to 500° C. at a heating rate of 5° C. / min and maintained for 4 h. After natural cooling, the powder was taken out and ground to obtain a gray composite material, i.e., a tubular nickel-doped carbon nitride material.

[0077] Example 8

[0078] A method for preparing a single-atom nickel-doped carbon nitride composite material comprises the following steps:

[0079] (1) Take cyanuric acid and melamine in a molar mass ratio of 1:1 as carbon nitride precursors, add them into 150 mL of deionized water, stir and react for 4 hours to obtain an emulsion.

[0080] (2) adding nickel sulfate and auxiliary ethanol to the emulsion prepared in step (1), stirring with a magnetic stirrer for 1 hour at a speed of 200 r / min to completely mix the emulsion to obtain a mixture, wherein the molar mass ratio of the ethanol to the nickel sulfate is 1:40; and the mass ratio of the nickel sulfate to the melamine is 14%.

[0081] (3) The mixture obtained in step (2) was placed in a forced air drying oven, dried at 105° C. for 24 h, and ground into powder.

[0082] (4) The powder was transferred into an alumina crucible with a lid, and then placed in a muffle furnace. In a nitrogen atmosphere, the temperature was increased to 500° C. at a heating rate of 5° C. / min and maintained for 4 h. After natural cooling, the powder was taken out and ground to obtain a gray composite material, i.e., a tubular nickel-doped carbon nitride material.

[0083] Comparative Example 1

[0084] (1) Take cyanuric acid and melamine in a molar mass ratio of 1:1 as carbon nitride precursors, add them into 150 mL of deionized water, stir and react for 4 hours to obtain an emulsion.

[0085] (2) The mixture obtained in step (1) was placed in a forced air drying oven, dried at 105° C. for 24 h, and ground into powder.

[0086] (3) The powder was transferred into an alumina crucible with a lid, and then placed in a muffle furnace. Under a nitrogen atmosphere, the temperature was raised to 500° C. at a heating rate of 5° C. / min and maintained for 4 h. After natural cooling, the powder was taken out and ground to obtain gC 3 N 4 , then to gC 3 N 4Peroxymonosulfate was added to construct a Fenton-like reaction system to degrade phenol.

[0087] Comparative Example 2

[0088] To Ni (NO 3 ) 2 6H 2 O was degraded by adding peroxymonosulfate to construct a Fenton-like reaction system.

[0089] Comparative Example 3

[0090] Only peroxymonosulfate was added to the pollutant to degrade phenol.

[0091] Results Analysis

[0092] Figure 1 The composite materials of Examples 1 to 4 of the present invention and the composite materials with only nickel salt, only peroxymonosulfate and gC added 3 N 4 The degradation rate results show that the degradation rate of phenol by the composite material Ni / CN-14% prepared by the present invention reaches 91.9%, while gC 3 N 4 The degradation rate is only 47.5%.

[0093] Figure 2 The cyclic test results of the degradation rate of the composite material prepared in Example 1 of the present invention show that the degradation rate of phenol in the composite material can still reach 85.5% after four times of repeated use.

[0094] Figure 3 The surface morphology of the composite material Ni / CN prepared in Example 1 of the present invention shows that the composite material Ni / CN is composed of many tubular structures with a size of micrometer level. This is mainly due to the addition of an additive in the present invention, which bridges nickel and melamine in an aqueous solution, and nickel atoms are evenly dispersed on the surface of melamine. During the thermal polycondensation process, the bridging effect of the additive affects the thermal polycondensation process of melamine, causing melamine to grow in one direction, and the presence of nickel atoms causes it to grow into a tubular structure.

[0095] Figure 4 This is a transmission electron microscope image of the composite material Ni / CN prepared in Example 1 of the present invention. It can be seen from the image that the composite material Ni / CN has good light transmittance and is a thin sheet structure with flat edges.

[0096] Figure 5 This is a high-resolution transmission electron microscopy image of the composite material Ni / CN prepared in Example 1 of the present invention. No Ni oxide particles and lattice fringes are observed in the image, indicating that Ni is in an amorphous state.

[0097] Figure 6 This is the EDS spectrum of the Ni / CN surface of the composite material prepared in Example 1 of the present invention. The EDS analysis results show that Ni is successfully incorporated into the composite material and is evenly distributed.

[0098] Figure 7 The XRD spectrum of the composite material Ni / CN prepared in Example 1 of the present invention shows that the XRD spectrum corresponds to gC 3 N 4 The crystal planes of (100) and (002) are not observed, and no characteristic peaks of any nickel-related metal oxides are observed, which further proves that the nickel in the composite is amorphous.

[0099] Figure 8 The composite material Ni / CN prepared in Example 1 of the present invention and the pure gC prepared using melamine as precursor 3 N 4 The specific surface area report data summary shows that the BET area of ​​the composite material prepared in Example 1 of the present invention reaches 114.0208 m 2 / g, while pure gC obtained from melamine as a precursor 3 N 4 The specific surface area is only 8m 2 / g, the composite material of the present invention is 14 times that of the composite material. The large specific surface area of ​​the composite material prepared by the present invention is mainly due to the selection of auxiliary agents. The added auxiliary agents are organic matter, which will volatilize during the thermal polycondensation process. The volatilization of organic matter will make the polycondensation product of melamine more fluffy. Compared with traditional carbon nitride, the internal and external areas are significantly increased.

[0100] Compared with the preparation method of Example 1, the soluble nickel salt is replaced by nickel chloride hexahydrate or nickel sulfate, and the auxiliary agent is replaced by dimethylene sulfoxide or ethanol. The prepared tubular amorphous nickel-doped carbon nitride material has a large specific surface area and can combine with peroxymonosulfate to achieve a good catalytic degradation effect on phenol.

[0101] In summary, the present invention uses melamine and cyanuric acid as carbon nitride precursors, mixes to obtain an emulsion, adds a soluble nickel salt and an auxiliary agent to the emulsion, utilizes the advantage that pyridine nitrogen with abundant lone pair electrons in the carbon nitride precursor molecule can be used as a transition metal anchoring position, prepares a tubular nickel-doped carbon nitride catalyst by a simple thermal polycondensation method, and constructs an efficient Fenton-like reaction system with permonosulfate to degrade phenol wastewater. The nickel atoms in the catalyst prepared by the present invention can directly react with permonosulfate to generate sulfate radicals with strong oxidizing properties, and the sulfate radicals can oxidize and decompose organic matter to generate carbon dioxide and water, while the nickel atoms are reduced to a high-valent state, and the catalyst carrier carbon nitride can transmit electrons to reduce the nickel atoms, and the reduced nickel atoms continue to participate in the oxidation of permonosulfate to generate sulfate radicals, and finally the phenol is decomposed and oxidized.

[0102] It should be noted that when the present invention relates to a numerical range, it should be understood that the two endpoints of each numerical range and any value between the two endpoints can be selected. Since the steps and methods used are the same as those in the embodiments, in order to avoid redundant description, the present invention describes a preferred embodiment. Although the preferred embodiments of the present invention have been described, once those skilled in the art know the basic creative concept, they can make other changes and modifications to these embodiments. Therefore, the attached protection scope is intended to be interpreted as including the preferred embodiment and all changes and modifications that fall within the scope of the present invention.

[0103] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention belong to the protection scope of the present invention, the present invention is also intended to include these modifications and variations.

Claims

1. A method for preparing a tubular amorphous nickel-doped carbon nitride material, characterized in that: The following steps are involved: Melamine and cyanuric acid are used as carbon nitride precursors, added into water, mixed and stirred to obtain an emulsion; Taking a soluble nickel salt as a nickel source, adding the soluble nickel salt and an auxiliary agent to the emulsion, mixing and stirring to obtain a mixed sample, and drying and grinding the mixed sample to obtain a powder; The powder is subjected to a heating treatment at a temperature of 450° C. to 600° C. to prepare a tubular amorphous nickel-doped carbon nitride material by a thermal polycondensation method; The auxiliary agent is dimethyl sulfoxide or 2-methylimidazole; The molar ratio of the auxiliary agent to the soluble nickel salt is 1:10-80.

2. The method for preparing a tubular amorphous nickel-doped carbon nitride material according to claim 1, characterized in that: The nickel source is one of nickel nitrate hexahydrate, nickel chloride hexahydrate and nickel sulfate.

3. The method for preparing a tubular amorphous nickel-doped carbon nitride material according to claim 1, characterized in that: The heating treatment time is 2 h to 6 h.

4. The method for preparing a tubular amorphous nickel-doped carbon nitride material according to claim 1, characterized in that: The mass fraction of the soluble nickel salt in melamine is 5% to 30%.

5. The method for preparing a tubular amorphous nickel-doped carbon nitride material according to claim 1, characterized in that: The dosage ratio of melamine, cyanuric acid and water is 1-5 mol:1-5 mol:150 mL.

6. A tubular amorphous nickel-doped carbon nitride material prepared according to the preparation method according to any one of claims 1 to 5, characterized in that: The nickel-doped carbon nitride material consists of a tubular structure with a size of micrometer level.

7. A Fenton-like reaction system, characterized in that: The tubular amorphous nickel-doped carbon nitride material according to claim 6 is constructed with peroxymonosulfate.

8. The Fenton-like reaction system according to claim 7, characterized in that: Application of the Fenton-like reaction system in degrading phenol wastewater.

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