A monometal-doped FeTi / C heterogeneous Fenton-like nanocatalyst, its preparation method and application

Abstract

This invention discloses a single-metal-doped FeTi / C heterogeneous Fenton-like nanocatalyst, its preparation method, and its application, belonging to the field of Fenton catalyst technology. The method includes: dissolving a metal salt and ferric nitrate in water to obtain an M-Fe mixed solution; mixing the M-Fe mixed solution with anhydrous ethanol solution of tetrabutyl titanate, then stirring and sonicating, adding ammonia solution dropwise until a gel-like solid is formed, aging, and drying to obtain an M-FeTiOx catalyst precursor; calcining the M-FeTiOx catalyst precursor under a reducing atmosphere to obtain a single-metal-doped M-FeTiOx catalyst; mixing the single-metal-doped M-FeTiOx catalyst with dechlorinated pretreated polyvinyl chloride powder, and then performing microwave pyrolysis to obtain a single-metal-doped FeTi / C nanocatalyst. The preparation process of this invention uses microwave pyrolysis, which is energy-efficient, has mild reaction conditions, and the prepared catalyst is easy to recover and produces no secondary pollution. It can be widely used in the degradation treatment of industrial phenol-containing wastewater and has significant industrial application prospects in environmental engineering and resource recycling.

Description

Technical Field

[0001] This invention relates to the field of Fenton catalyst technology, specifically to a single-metal doped FeTi / C heterogeneous Fenton nanocatalyst, its preparation method, and its application. Background Technology

[0002] Phenol, a typical highly toxic and recalcitrant organic pollutant in wastewater from industries such as coking, chemical, and pharmaceutical manufacturing, poses a serious threat to the ecological environment and human health. Heterogeneous Fenton catalysis technology has become one of the mainstream technologies for treating phenol-containing wastewater due to its advantages such as easy catalyst recovery and the absence of secondary pollution from iron sludge. Among existing technologies, the FeTi / C heterogeneous Fenton catalyst prepared using waste PVC as a carbon source possesses both resource recycling and catalytic degradation potential, but its performance still faces key bottlenecks: the active sites mainly depend on a single iron component, Fe... 2+ / Fe 3+ Limited redox cycle efficiency leads to increased production of hydroxyl radicals (·OH) and superoxide radicals (·O2). - The insufficient generation rate of reactive oxygen species such as iron (IOS) makes it difficult to achieve rapid mineralization of phenol. Furthermore, single iron-based systems are prone to deactivation during continuous operation due to iron species aggregation or loss, resulting in insufficient cycle stability. While some studies have attempted to introduce a second metal to construct a bimetallic synergistic system to address these shortcomings, the significant differences in ionic radius, valence state characteristics, and interaction mechanisms between different metals and the carbon support, along with their impact on the morphology of the carbon support, the dispersion of active sites, and the overall catalytic performance, remain unclear. Therefore, how to rationally select the type of doping metal and directionally control the structure and interfacial properties of the catalyst to overcome the performance bottleneck of single iron-based catalysts remains a pressing technical challenge. Summary of the Invention

[0003] To address the issues of insufficient catalytic activity and stability of FeTi / C heterogeneous Fenton catalysts, the present invention aims to provide a method for preparing a single-metal-doped FeTi / C heterogeneous Fenton-like nanocatalyst, specifically comprising the following steps: (1) Dissolve metal salt and ferric nitrate in water to obtain M-Fe mixed solution; mix M-Fe mixed solution with tetrabutyl titanate anhydrous ethanol solution to obtain mixed system, then stir, sonicate, add ammonia solution dropwise until a gel solid is formed, let stand for aging and dry to obtain M-FeTiOx catalyst precursor.

[0004] (2) The M-FeTiOx catalyst precursor was calcined under a reducing atmosphere to obtain a single metal doped M-FeTiOx catalyst, where x = 3-5.

[0005] (3) The polyvinyl chloride powder is dechlorinated under an argon atmosphere and then ground to obtain pretreated polyvinyl chloride powder.

[0006] (4) The monometallic doped M-FeTiOx catalyst (M represents one of Co, Mn, Mg) was mixed with pretreated polyvinyl chloride powder, and microwave pyrolysis was performed after argon purging to obtain monometallic doped FeTi / C heterogeneous Fenton nanocatalyst.

[0007] Preferably, in step (1) of the present invention, the metal salt is one of cobalt nitrate, magnesium nitrate, and manganese nitrate; the molar ratio of the metal salt to ferric nitrate is 0.1:1.

[0008] Preferably, in step (1) of the present invention, the concentration of the metal salt in the M-Fe mixed solution is 0.1 mol / L and the concentration of ferric nitrate is 1.0 mol / L.

[0009] Preferably, the concentration of the tetrabutyl titanate anhydrous ethanol solution in step (1) of the present invention is 200 g / L.

[0010] Preferably, in step (1) of the present invention, the molar ratio of tetrabutyl titanate in the anhydrous ethanol solution to ferric nitrate in the M-Fe mixed solution is 1:1.

[0011] Preferably, the mass percentage concentration of the ammonia solution in step (1) of the present invention is 10%-15%.

[0012] Preferably, in step (1) of the present invention, the stirring and ultrasonic temperature is 25-35℃ and the time is 30-60min; the standing aging time is 12-24 hours; the drying temperature is 80-100℃ and the drying time is 36-48 hours; the dried precursor is ground to a particle size ≤74μm.

[0013] Preferably, in step (2) of the present invention, the reducing atmosphere is a mixture of 5% hydrogen and 95% argon by volume, and the flow rate of the reducing atmosphere is 100-150 mL / min.

[0014] Preferably, in step (2) of the present invention, the roasting temperature is 600°C and the roasting time is 1 hour.

[0015] Preferably, the argon flow rate in step (3) of the present invention is 100-150 mL / min.

[0016] Preferably, the dechlorination treatment conditions in step (3) of the present invention are: treatment at 350°C for 8-10 minutes.

[0017] Preferably, in step (4) of the present invention, the mass ratio of the monometallic doped M-FeTiOx catalyst to the pretreated polyvinyl chloride powder is 1:1.

[0018] Preferably, the conditions for argon purging in step (4) of the present invention are: argon flow rate of 100-200 mL / min and purging time of 15 min; Preferably, the microwave pyrolysis conditions in step (4) of the present invention are: microwave power 800W, pyrolysis temperature 700℃, and pyrolysis time 20-40 seconds.

[0019] The purpose of this invention is to provide a single-metal-doped FeTi / C heterogeneous Fenton-like nanocatalyst prepared by the method described above.

[0020] The purpose of this invention is to provide an application of a single-metal-doped FeTi / C heterogeneous Fenton-like nanocatalyst for the catalytic degradation of phenol in water.

[0021] This invention provides a single-metal-doped FeTi / C heterogeneous Fenton-like nanocatalyst, its preparation method, and its application, which have the following beneficial effects: (1) This invention constructs a highly efficient bimetallic synergistic catalytic system through single-metal doping with Co, Mg, and Mn, which accelerates electron transfer and Fe³⁺. + / Fe² + The recycling process significantly improves the degradation efficiency and cycle stability of phenol, solving the problems of insufficient activity and easy deactivation of traditional catalysts.

[0022] (2) The present invention adopts microwave pyrolysis process, which has short preparation time, low energy consumption, and mild and controllable operating conditions; the unified preparation parameters facilitate system comparison and process upgrade, and are suitable for industrial production and promotion.

[0023] (3) This invention uses dechlorinated polyvinyl chloride as a carbon source and realizes the high-value utilization of solid waste through microwave pyrolysis, avoiding secondary pollution. At the same time, the heterogeneous catalytic system makes the catalyst easy to separate and recover, and there are no secondary pollutants such as iron sludge, which is in line with the concept of green development. Attached Figure Description

[0024] Figure 1 These are the XRD patterns of the Co-FeTi / C, Mg-FeTi / C, and Mn-FeTi / C heterogeneous Fenton-like catalysts prepared in Examples 1-3 of this invention. Figure 1 In the middle (a), the XRD pattern of Co-FeTi / C is shown. Figure 1 (b) is the XRD pattern of Mg-FeTi / C. Figure 1 (c) is the XRD pattern of Mn-FeTi / C.

[0025] Figure 2 These are SEM images of the Co-FeTi / C, Mg-FeTi / C, and Mn-FeTi / C heterogeneous Fenton-like catalysts prepared in Examples 1-3 of this invention. Figure 2In the middle (a), the SEM image of Co-FeTi / C is shown (scale bar 2 μm). Figure 2 (b) is a SEM image of Co-FeTi / C (scale bar 500 nm). Figure 2 (c) is a SEM image of Mg-FeTi / C (scale bar 2 μm). Figure 2 The middle (d) image is a SEM image of Mg-FeTi / C (scale bar 500 nm). Figure 2 (e) is the SEM image of Mn-FeTi / C (scale bar 2 μm). Figure 2 In the middle (f), the SEM image of Mn-FeTi / C is shown (scale bar 500 nm).

[0026] Figure 3 The graphs show the degradation effects of the Co-FeTi / C, Mg-FeTi / C, and Mn-FeTi / C heterogeneous Fenton-like catalysts prepared in Examples 1-3 of this invention on phenol in water. Figure 3 Image (a) shows the initial degradation effect. Figure 3 (b) shows the degradation effect after the 5th cycle.

[0027] Figure 4 This is the XRD pattern of the FeTi / C heterogeneous Fenton-like catalyst prepared in Comparative Example 1 of this invention.

[0028] Figure 5 The graph shows the degradation effect of the FeTi / C heterogeneous Fenton catalyst prepared in Comparative Example 1 of this invention on phenol in water. Figure 5 Image (a) shows the initial degradation effect. Figure 5 (b) shows the degradation effect after the 5th cycle. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Example 1 A method for preparing a Co-FeTi / C heterogeneous Fenton-like nanocatalyst includes the following steps: (1) Cobalt nitrate and ferric nitrate were dissolved in water, wherein the molar ratio of cobalt nitrate to ferric nitrate was 0.1:1, to obtain a Co-Fe mixed solution (the concentration of cobalt nitrate in the Co-Fe mixed solution was 0.1 mol / L); tetrabutyl titanate was dissolved in anhydrous ethanol to prepare an anhydrous ethanol solution of tetrabutyl titanate with a concentration of 200 g / L; the Co-Fe mixed solution was mixed with the anhydrous ethanol solution of tetrabutyl titanate (the tetrabutyl titanate in the anhydrous ethanol solution of tetrabutyl titanate and the ferric nitrate in the Co-Fe mixed solution were mixed). The molar ratio of the two components was 1:1 to obtain a mixed system. The mixed system was placed in a water bath at 30°C and stirred for 30 min, followed by sonication at 30°C for 30 min. Under the conditions of stirring speed of 150 r / min and stirring temperature of 30°C, a 10% ammonia solution was added dropwise to the mixed system until a gel-like solid was formed. The gel-like solid was allowed to stand at room temperature for 24 hours and then dried in a drying oven at 80°C for 48 hours to obtain the Co-FeTiOx catalyst precursor, x=3-5.

[0031] (2) The Co-FeTiOx catalyst precursor was ground into powder with a particle size ≤74μm and placed in a tube furnace. It was calcined in a mixed reducing atmosphere consisting of 5% hydrogen and 95% argon (the flow rate of the reducing atmosphere was 100mL / min, the calcination temperature was 600℃, and the calcination time was 1 hour) to obtain a single metal doped Co-FeTiOx catalyst with x=3-5.

[0032] (3) Place the polyvinyl chloride powder in a tube furnace and perform dechlorination pretreatment for 10 min at a pretreatment temperature of 350℃ and an argon atmosphere with a flow rate of 100 mL / min. Grind the powder to obtain pretreated polyvinyl chloride powder (the chlorine content of the pretreated polyvinyl chloride powder is 0.41%).

[0033] (4) The single metal doped Co-FeTiOx catalyst and the pretreated polyvinyl chloride powder were mixed in a mass ratio of 1:1 and placed in a microwave reaction vessel. The reaction vessel was first purged with argon gas at 200 mL / min for 15 min to remove the air in the reaction vessel. Then, the microwave power was turned on at 800 W and the temperature was raised to 700 °C and microwave pyrolysis was maintained for 30 s to obtain the Co-FeTi / C heterogeneous Fenton nanocatalyst.

[0034] Example 2 A method for preparing a heterogeneous Fenton-like Mg-FeTi / C nanocatalyst includes the following steps: (1) Dissolve magnesium nitrate and ferric nitrate in water, wherein the molar ratio of magnesium nitrate to ferric nitrate is 0.1:1, to obtain a Mg-Fe mixed solution (the concentration of magnesium nitrate in the Mg-Fe mixed solution is 0.1 mol / L); dissolve tetrabutyl titanate in anhydrous ethanol to prepare a tetrabutyl titanate anhydrous ethanol solution with a concentration of 200 g / L; mix the Mg-Fe mixed solution with the tetrabutyl titanate anhydrous ethanol solution (the tetrabutyl titanate in the tetrabutyl titanate anhydrous ethanol solution and the ferric nitrate in the Mg-Fe mixed solution are mixed). The molar ratio of the two components was 1:1 to obtain a mixed system. The mixed system was placed in a water bath at 30°C and stirred for 30 min, followed by sonication at 30°C for 30 min. Under the conditions of stirring speed of 150 r / min and stirring temperature of 30°C, a 10% ammonia solution was added dropwise to the mixed system until a gel-like solid was formed. The gel-like solid was allowed to stand at room temperature for 24 hours and then dried in a drying oven at 80°C for 48 hours to obtain the Mg-FeTiOx catalyst precursor, x=3-5.

[0035] (2) The Mg-FeTiOx catalyst precursor was ground into powder with a particle size ≤74μm and placed in a tube furnace. It was calcined in a mixed reducing atmosphere consisting of 5% hydrogen and 95% argon (the flow rate of the reducing atmosphere was 100mL / min, the calcination temperature was 600℃, and the calcination time was 1 hour) to obtain a single metal doped Mg-FeTiOx catalyst with x=3-5.

[0036] (3) Place the polyvinyl chloride powder in a tube furnace and perform dechlorination pretreatment for 10 min at a pretreatment temperature of 350℃ and an argon atmosphere with a flow rate of 100 mL / min. Grind the powder to obtain pretreated polyvinyl chloride powder (the chlorine content of the pretreated polyvinyl chloride powder is 0.41%).

[0037] (4) Mix the monometallic doped Mg-FeTiOx catalyst with pretreated polyvinyl chloride powder at a mass ratio of 1:1 and place it in a microwave reaction vessel. First, purge the reaction vessel with argon gas at 200 mL / min for 15 min to remove the air in the reaction vessel. Then, turn on the microwave power of 800 W and heat it to 700 °C and maintain microwave pyrolysis for 30 seconds to obtain Mg-FeTi / C heterogeneous Fenton nanocatalyst.

[0038] Example 3 A method for preparing a heterogeneous Mn-FeTi / C Fenton-like nanocatalyst includes the following steps: (1) Dissolve manganese nitrate and ferric nitrate in water, wherein the molar ratio of manganese nitrate to ferric nitrate is 0.1:1, to obtain a Mn-Fe mixed solution (the concentration of manganese nitrate in the Mn-Fe mixed solution is 0.1 mol / L); dissolve tetrabutyl titanate in anhydrous ethanol to prepare a tetrabutyl titanate anhydrous ethanol solution with a concentration of 200 g / L; mix the Mn-Fe mixed solution with the tetrabutyl titanate anhydrous ethanol solution (the tetrabutyl titanate in the tetrabutyl titanate anhydrous ethanol solution and the ferric nitrate in the Mn-Fe mixed solution are mixed). The molar ratio of the two components was 1:1 to obtain a mixed system. The mixed system was placed in a water bath at 30°C and stirred for 30 min, followed by sonication at 30°C for 30 min. Under the conditions of stirring speed of 150 r / min and stirring temperature of 30°C, a 10% ammonia solution was added dropwise to the mixed system until a gel-like solid was formed. The gel-like solid was allowed to stand at room temperature for 24 hours and then dried in a drying oven at 80°C for 48 hours to obtain the Mn-FeTiOx catalyst precursor, x=3-5.

[0039] (2) The Mn-FeTiOx catalyst precursor was ground into powder with a particle size ≤74μm and placed in a tube furnace. It was calcined in a mixed reducing atmosphere consisting of 5% hydrogen and 95% argon (the flow rate of the reducing atmosphere was 100mL / min, the calcination temperature was 600℃, and the calcination time was 1 hour) to obtain a single metal doped Mn-FeTiOx catalyst with x=3-5.

[0040] (3) Place the polyvinyl chloride powder in a tube furnace and perform dechlorination pretreatment for 10 min at a pretreatment temperature of 350℃ and an argon atmosphere with a flow rate of 100 mL / min. Grind the powder to obtain pretreated polyvinyl chloride powder (the chlorine content of the pretreated polyvinyl chloride powder is 0.41%).

[0041] (4) Mix the single metal doped Mn-FeTiOx catalyst with pretreated polyvinyl chloride powder at a mass ratio of 1:1 and place it in a microwave reaction vessel. First, purge the reaction vessel with argon gas at 200 mL / min for 15 min to remove the air in the reaction vessel. Then, turn on the microwave power of 800 W and heat it to 700 °C and maintain microwave pyrolysis for 30 seconds to obtain Mn-FeTi / C heterogeneous Fenton nanocatalyst.

[0042] The Co-FeTi / C, Mg-FeTi / C, and Mn-FeTi / C heterogeneous Fenton-like nanocatalysts prepared in Examples 1-3 were characterized and analyzed by XRD and SEM, respectively. From the XRD patterns (… Figure 1It can be seen that all three monometallic doped FeTi / C catalysts exhibit the characteristic of multi-phase coexistence. In addition to TiO2, Fe2Ti3O9, Fe3C, and FeTiO3, Co3Fe7 intermetallic compounds and CoFe2O4 spinel phases also appear in Co-FeTi / C, indicating that Co and Fe have successfully constructed bimetallic synergistic catalytic sites. Figure 1 (a) Characteristic peaks of MgO and MgTiO3 were detected in Mg-FeTi / C, indicating that Mg exists stably in the form of oxides and titanates, and inhibits the aggregation and leaching of Fe species through lattice regulation. Figure 1 In (b), diffraction peaks for Fe and Mn3O4 appeared in Mn-FeTi / C, indicating that Mn doping promoted the reduction of Fe, forming Mn3O4. 2+ / Mn 3+ with Fe 2+ / Fe 3+ The redox cycle provides abundant active sites for Fenton-like reactions. Figure 1 (c)

[0043] From SEM images ( Figure 2 The microstructures of the three catalysts can be clearly observed. It can be found that the carbon support in Co-FeTi / C is mainly carbon nanotubes, while in Mg-FeTi / C and Mn-FeTi / C, the carbon support consists of carbon nanotubes and some carbon particles. This is because Co and Fe form highly catalytically active bimetallic phases (such as Co3Fe7 intermetallic compounds and CoFe2O4 spinel). Under pyrolysis conditions of 700℃, these bimetallic nanoparticles act as highly efficient catalysts, directionally inducing the growth of carbon sources generated from PVC decomposition into uniformly sized and structurally complete carbon nanotubes. In Mg-FeTi / C, Mg mainly exists in the form of MgO and MgTiO3. These oxides themselves have low catalytic activity for carbon nanotube growth. Although Fe-based catalysts (such as Fe3C and FeTiO3) can still catalyze the generation of carbon nanotubes, the presence of Mg dilutes the concentration of the active metal, causing some carbon sources to fail to be completely converted into carbon nanotubes and instead deposit as carbon particles. In Mn-FeTi / C, Mn doping promotes the formation of Fe and Mn3O4. Although these phases also possess some catalytic activity, their catalytic efficiency and selectivity are inferior to those of the Co-Fe system under the pyrolysis conditions of this system. Therefore, some of the carbon source is converted into carbon nanotubes, while the rest forms carbon particles. Consequently, both carbon structures coexist in the SEM images of Mg-FeTi / C and Mn-FeTi / C.

[0044] Combination Figure 1 and Figure 2It can be seen that there are significantly more carbon nanotubes in Co-FeTi / C than in Mg-FeTi / C and Mn-FeTi / C, but its graphite diffraction peak is significantly lower than that of Mg-FeTi / C and Mn-FeTi / C. This indicates that the carbon particles in Mg-FeTi / C and Mn-FeTi / C are not completely disordered amorphous carbon, but rather amorphous carbon particles containing short-range ordered graphite-like microcrystals.

[0045] The Co-FeTi / C, Mg-FeTi / C, and Mn-FeTi / C heterogeneous Fenton-like nanocatalysts prepared in Examples 1-3 were applied to the catalytic degradation of phenol in water, and the results were as follows: Figure 3 As shown, it includes the following steps: (1) Take 100 mL of phenol aqueous solution with a concentration of 200 mg / L, adjust the pH of the phenol solution to 2.9-3.1 with sulfuric acid solution, and then add 30% H2O2 and Co-FeTi / C, Mg-FeTi / C and Mn-FeTi / C catalysts respectively. The amount of H2O2 added is 30 mmol / L, and the amount of catalyst added is 1000 mg / L.

[0046] (2) The above reaction system was placed in a water bath at 30°C for stirring and degradation. The stirring speed was 180 r / min. To more clearly observe the change of phenol degradation rate with degradation time, the catalytic degradation time was set to 11 groups, namely 0 min, 1 min, 2 min, 3 min, 4 min, 5 min, 6 min, 7 min, 8 min, 9 min, and 10 min.

[0047] (3) After each degradation experiment, the reaction solution was filtered, and the degradation rate of phenol in water by Co-FeTi / C, Mg-FeTi / C and Mn-FeTi / C catalysts was calculated by measuring the concentration of phenol in the filtered solution.

[0048] like Figure 3 As shown in (a), in the application of catalytic degradation of phenol in water, the heterogeneous Fenton-like nanocatalyst Co-FeTi / C prepared in Example 1 showed a degradation rate of 92.43% within 10 min, and exhibited sustained stability after five cycles of degradation, with a degradation rate of 90.44%; the heterogeneous Fenton-like nanocatalyst Mg-FeTi / C prepared in Example 2 showed a degradation rate of 92% within 10 min, and a degradation rate of 89% after five cycles of degradation; the heterogeneous Fenton-like nanocatalyst Mn-FeTi / C prepared in Example 3 showed a degradation rate of 92.19% within 10 min, and a degradation rate of 89.19% after five cycles of degradation (e.g., ...). Figure 3 (b)

[0049] Example 4 A method for preparing a Co-FeTi / C heterogeneous Fenton-like nanocatalyst includes the following steps: (1) Cobalt nitrate and ferric nitrate were dissolved in water, wherein the molar ratio of cobalt nitrate to ferric nitrate was 0.1:1, to obtain a Co-Fe mixed solution (the concentration of cobalt nitrate in the Co-Fe mixed solution was 0.1 mol / L); tetrabutyl titanate was dissolved in anhydrous ethanol to prepare an anhydrous ethanol solution of tetrabutyl titanate with a concentration of 200 g / L; the Co-Fe mixed solution was mixed with the anhydrous ethanol solution of tetrabutyl titanate (the tetrabutyl titanate in the anhydrous ethanol solution of tetrabutyl titanate and the ferric nitrate in the Co-Fe mixed solution were mixed). The molar ratio of the two components was 1:1 to obtain a mixed system. The mixed system was placed in a water bath at 25°C and stirred for 60 min, followed by sonication at 25°C for 60 min. Under the conditions of stirring speed of 150 r / min and stirring temperature of 25°C, an ammonia solution with a mass percentage concentration of 12% was added dropwise to the mixed system until a gel-like solid was formed. The gel-like solid was allowed to stand at room temperature for 12 hours and then dried in a drying oven at 90°C for 40 hours to obtain the Co-FeTiOx catalyst precursor, x=3-5.

[0050] (2) The Co-FeTiOx catalyst precursor was ground into powder with a particle size ≤74μm and placed in a tube furnace. It was calcined in a mixed reducing atmosphere consisting of 5% hydrogen and 95% argon (the flow rate of the reducing atmosphere was 120mL / min, the calcination temperature was 600℃, and the calcination time was 1 hour) to obtain a single metal doped Co-FeTiOx catalyst with x=3-5.

[0051] (3) Place the polyvinyl chloride powder in a tube furnace and perform dechlorination pretreatment for 8 minutes at a pretreatment temperature of 350°C and an argon atmosphere with a flow rate of 120 mL / min. Grind the powder to obtain pretreated polyvinyl chloride powder (the chlorine content of the pretreated polyvinyl chloride powder is 0.53%).

[0052] (4) The single metal doped Co-FeTiOx catalyst and the pretreated polyvinyl chloride powder were mixed in a mass ratio of 1:1 and placed in a microwave reaction vessel. The reaction vessel was first purged with argon gas at 100 mL / min for 15 min to remove the air in the reaction vessel. Then, the microwave power was turned on at 800 W and the temperature was raised to 700 °C and microwave pyrolysis was maintained for 20 seconds to obtain the Co-FeTi / C heterogeneous Fenton nanocatalyst.

[0053] The heterogeneous Fenton-like nanocatalyst Co-FeTi / C prepared in this embodiment exhibited a degradation rate of 92.08% within 10 min, and a degradation rate of 89.86% after five cycles. Example 5 A method for preparing a Co-FeTi / C heterogeneous Fenton-like nanocatalyst includes the following steps: (1) Cobalt nitrate and ferric nitrate were dissolved in water, wherein the molar ratio of cobalt nitrate to ferric nitrate was 0.1:1, to obtain a Co-Fe mixed solution (the concentration of cobalt nitrate in the Co-Fe mixed solution was 0.1 mol / L); tetrabutyl titanate was dissolved in anhydrous ethanol to prepare a tetrabutyl titanate anhydrous ethanol solution with a concentration of 200 g / L; the Co-Fe mixed solution was mixed with the tetrabutyl titanate anhydrous ethanol solution (the concentration of tetrabutyl titanate in the tetrabutyl titanate anhydrous ethanol solution was 0.1 mol / L, and the concentration of ferric nitrate in the Co-Fe mixed solution was 0.1 mol / L). A mixed system was obtained by mixing the components in a molar ratio of 1:1. The mixed system was then placed in a water bath at 35°C and stirred for 45 min, followed by sonication at 35°C for 45 min. At a stirring speed of 150 r / min and a stirring temperature of 35°C, an ammonia solution with a mass percentage concentration of 15% was added dropwise to the mixed system until a gel-like solid was formed. The gel-like solid was allowed to stand at room temperature for 18 hours and then dried in a drying oven at 100°C for 36 hours to obtain the Co-FeTiOx catalyst precursor, where x = 3-5.

[0054] (2) The Co-FeTiOx catalyst precursor was ground into powder with a particle size ≤74μm and placed in a tube furnace. It was calcined in a mixed reducing atmosphere consisting of 5% hydrogen and 95% argon (the flow rate of the reducing atmosphere was 150mL / min, the calcination temperature was 600℃, and the calcination time was 1 hour) to obtain a single metal doped Co-FeTiOx catalyst with x=3-5.

[0055] (3) Place the polyvinyl chloride powder in a tube furnace and perform dechlorination pretreatment for 9 min at a pretreatment temperature of 350℃ and an argon atmosphere with a flow rate of 150 mL / min. Grind the powder to obtain pretreated polyvinyl chloride powder (the chlorine content of the pretreated polyvinyl chloride powder is 0.46%).

[0056] (4) The single metal doped Co-FeTiOx catalyst and the pretreated polyvinyl chloride powder were mixed in a mass ratio of 1:1 and placed in a microwave reaction vessel. The reaction vessel was first purged with argon gas at 150 mL / min for 15 min to remove the air in the reaction vessel. Then, the microwave power was turned on at 800 W and the temperature was raised to 700 °C and microwave pyrolysis was maintained for 40 seconds to obtain the Co-FeTi / C heterogeneous Fenton nanocatalyst.

[0057] The heterogeneous Fenton-like nanocatalyst Co-FeTi / C prepared in this embodiment exhibited a degradation rate of 92.16% within 10 min and a degradation rate of 89.93% after five cycles.

[0058] Comparative Example 1 The difference between this comparative example and Example 1 is that no single metal doping was performed, and a FeTi / C heterogeneous Fenton-like nanocatalyst was prepared.

[0059] from Figure 4 It can be seen that the main phases of the FeTi / C heterogeneous Fenton-like nanocatalyst obtained in Comparative Example 1 are TiO2, Fe2Ti3O9, Fe3C, FeTiO3, and Fe, indicating that the main activity of this material for phenol degradation comes from Fe2+. + / Fe³ + The redox cycle.

[0060] The FeTi / C heterogeneous Fenton-like nanocatalyst prepared in Comparative Example 1 was applied to the catalytic degradation of phenol in water. The operation steps were the same as those for the catalysts prepared in Examples 1-3, and the degradation effect was as follows: Figure 5 As shown, according to Figure 5 As shown in Figure (a), the FeTi / C catalyst prepared in the comparative example exhibits a phenol degradation rate of 88.53% within 10 min, but only 82.36% after five cycles. Figure 5 In (b), the degradation efficiency of phenol is far lower than that of heterogeneous Fenton nanocatalysts such as Co-FeTi / C, Mg-FeTi / C, and Mn-FeTi / C. Because FeTi / C without Co, Mn, or Mg doping cannot construct a synergistic catalytic system with the Fe active sites through the doped metals, it is difficult to significantly accelerate the electron transfer rate during the reaction and thus cannot efficiently promote Fe degradation. 3+ To Fe 2+ The rapid reduction of phenol by Fe makes it difficult to continuously activate H2O2 to generate strong oxidizing hydroxyl radicals (•OH), resulting in low phenol degradation efficiency. Simultaneously, due to the lack of stabilizing effect of doped metals on the active sites, Fe components are more prone to leaching, causing the catalyst to degrade activity more rapidly during recycling. Therefore, the FeTi / C catalyst without doped metals exhibits significantly lower catalytic activity and cycling stability than Fenton-like catalysts modified with Co, Mg, and Mn doping, and its degradation effect on phenol is even worse.

[0061] Based on the above, this invention successfully prepared Co-FeTi / C, Mg-FeTi / C, and Mn-FeTi / C heterogeneous Fenton-like nanocatalysts. Compared with existing FeTi / C catalysts, the prepared catalysts have higher degradation efficiency for phenol, better cycle stability, and are easy to recover, enabling large-scale production and application. They have significant industrial application prospects in the fields of environmental engineering and resource recycling.

[0062] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A preparation method of a single metal-doped FeTi / C heterogeneous Fenton-like nanocatalyst, characterized in that, Specifically, the following steps are included: (1) Dissolve metal salt and ferric nitrate in water to obtain M-Fe mixed solution; mix M-Fe mixed solution with tetrabutyl titanate anhydrous ethanol solution to obtain mixed system, then stir, sonicate, add ammonia solution dropwise until a gel-like solid is formed, let stand for aging and dry to obtain M-FeTiOx catalyst precursor; (2) The M-FeTiOx catalyst precursor was calcined under a reducing atmosphere to obtain a single metal-doped M-FeTiOx catalyst, where x = 3-5; (3) The polyvinyl chloride powder was dechlorinated under an argon atmosphere and then ground to obtain pretreated polyvinyl chloride powder; (4) The single metal doped M-FeTiOx catalyst was mixed with pretreated polyvinyl chloride powder, and microwave pyrolysis was performed after argon purging to obtain a single metal doped FeTi / C heterogeneous Fenton nanocatalyst.

2. The preparation method of the single-metal doped FeTi / C heterogeneous Fenton-like nanocatalyst according to claim 1, characterized in that, The metal salt mentioned in step (1) is one of cobalt nitrate, magnesium nitrate, and manganese nitrate; the molar ratio of the metal salt to ferric nitrate is 0.1:1; the concentration of the metal salt in the M-Fe mixed solution is 0.1 mol / L and the concentration of ferric nitrate is 1.0 mol / L.

3. The preparation method of the single-metal doped FeTi / C heterogeneous Fenton-like nanocatalyst according to claim 1, characterized in that, The concentration of the tetrabutyl titanate anhydrous ethanol solution in step (1) is 200 g / L; the molar ratio of tetrabutyl titanate in the tetrabutyl titanate anhydrous ethanol solution to ferric nitrate in the M-Fe mixed solution is 1:1; and the mass percentage concentration of the ammonia solution is 10%-15%.

4. The preparation method of the single-metal doped FeTi / C heterogeneous Fenton-like nanocatalyst according to claim 1, characterized in that, The stirring and ultrasonication in step (1) are performed at a temperature of 25-35℃ for 30-60 min; the standing aging time is 12-24 hours; the drying temperature is 80-100℃ and the drying time is 36-48 hours; the dried precursor is ground to a particle size ≤74μm.

5. The preparation method of the single-metal doped FeTi / C heterogeneous Fenton-like nanocatalyst according to claim 1, characterized in that, The reducing atmosphere in step (2) is a mixture of 5% hydrogen and 95% argon by volume, and the flow rate of the reducing atmosphere is 100-150 mL / min; the calcination temperature is 600℃ and the calcination time is 1 hour.

6. The method for preparing a single-metal-doped FeTi / C heterogeneous Fenton-like nanocatalyst according to claim 1, characterized in that, The argon flow rate in step (3) is 100-150 mL / min; the dechlorination treatment conditions are: treatment at 350℃ for 8-10 min.

7. The preparation method of the single-metal doped FeTi / C heterogeneous Fenton-like nanocatalyst according to claim 1, characterized in that, The mass ratio of the monometallic doped M-FeTiOx catalyst to the pretreated polyvinyl chloride powder in step (4) is 1:

1.

8. The method for preparing a single-metal-doped FeTi / C heterogeneous Fenton-like nanocatalyst according to claim 1, characterized in that, The argon purging conditions in step (4) are: argon flow rate of 100-200 mL / min and purging time of 15 min; the microwave pyrolysis conditions are: microwave power of 800 W, pyrolysis temperature of 700 °C and pyrolysis time of 20-40 seconds.

9. A single-metal-doped FeTi / C heterogeneous Fenton-like nanocatalyst prepared by the method according to any one of claims 1 to 8.

10. The application of the single-metal doped FeTi / C heterogeneous Fenton nanocatalyst according to claim 9 in the catalytic degradation of phenol in water.

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