FeTi / C heterogeneous Fenton nano-catalyst as well as preparation method and application thereof

Abstract

The invention discloses a FeTi / C heterogeneous Fenton nano-catalyst as well as a preparation method and application thereof, and belongs to the technical field of Fenton catalysts. The preparation method comprises the following steps: preparing a FeTiOx catalyst by using a ferric nitrate solution and a tetrabutyl titanate solution, then mixing dechlorinated polyvinyl chloride powder as a carbon source with the FeTiOx catalyst, and loading FeTi metal by using carbon nanotubes generated in microwave pyrolysis and amorphous amorphous carbon as carbon carriers to obtain the FeTi / C heterogeneous Fenton nano catalyst. The unique tubular structure of the carbon nanotube in the catalyst provides a mass transfer channel for phenol molecules to quickly diffuse into the catalyst and contact with active sites, so that the effect of quickly degrading phenol is achieved. The method provides a thought for subsequent high-efficiency recovery and reutilization of waste PVC, and is energy-saving, efficient, green and environment-friendly, meanwhile, the catalyst is high in stability and catalytic activity, the degradation rate can reach 83.67%-90.89% in application to degradation of phenol in industrial wastewater, the stability is kept above 80%, the reaction conditions are mild, and the operation is simple.

Description

Technical Field

[0001] The present invention relates to the technical field of the preparation of Fenton catalysts, and particularly relates to an FeTi / C heterogeneous Fenton nanocatalyst, a preparation method thereof, and an application thereof. Background Art

[0002] As a typical organic pollutant, phenol widely exists in industrial wastewater. Due to the high toxicity and biological recalcitrance of phenol, it will cause serious harm to aquatic organisms, soil organisms, etc. after entering the environment, and will ultimately threaten the physical health of humans through the transfer and accumulation of the food chain.

[0003] The degradation efficiency of traditional treatment processes for phenol is limited. During the degradation of phenol, free radicals with strong oxidation ability decompose or mineralize phenol in the wastewater into harmless products. The heterogeneous Fenton catalyst mainly uses the impregnation method with activated carbon with a large specific surface area as the carrier. However, during the preparation process, there are deficiencies such as large pore sizes in the activated carbon carrier and ineffective adsorption of organic matter. However, due to the harsh reaction conditions of the traditional Fenton method, the catalyst cannot be recovered, increasing the treatment cost, and the large amount of iron sludge produced is likely to cause secondary pollution to the environment.

[0004] With the growth of production and consumption, the amount of waste polyvinyl chloride (PVC) has gradually increased. Traditional combustion of PVC will directly produce a large amount of pollutants, causing environmental pollution. How to recycle waste PVC is an urgent problem to be solved. Therefore, although using PVC as a carbon source to prepare a heterogeneous Fenton nano iron-based / C catalyst can reduce the influence of reaction conditions in the traditional Fenton method, increase the recovery rate of the catalyst, and reduce the generation of iron sludge, the improvement of its degradation rate of organic pollutants is not obvious. Summary of the Invention

[0005] The purpose of the present invention is to provide an FeTi / C heterogeneous Fenton nanocatalyst, a preparation method thereof, and an application thereof with PVC as a carbon source, so as to solve the problems existing in the traditional Fenton technology when degrading phenol in wastewater, such as being restricted by reaction conditions, difficult to recover the catalyst, and easy to cause secondary pollution.

[0006] A preparation method of an FeTi / C heterogeneous Fenton nanocatalyst comprises the following steps:

[0007] (1) Adding a ferric nitrate solution to a tetrabutyl titanate solution for mixing, stirring, and ultrasonic treatment, and then adding an ammonia water solution to the mixed solution in a stirred state until the mixed solution becomes a colloidal solid, standing for aging, and drying to obtain FeTiO x The catalyst precursor, x = 3 - 5;

[0008] (2) FeTiO xThe catalyst precursor is ground into a powder and placed in a tubular furnace, and calcined under a reducing atmosphere to obtain FeTiO x catalyst;

[0009] (3) Select PVC powder (polyvinyl chloride) as the carbon source and place it in a tubular furnace. Perform dechlorination treatment under an argon atmosphere, and grind the dechlorinated PVC powder to obtain pretreated PVC powder;

[0010] (4) Mix the FeTiO x catalyst with the pretreated PVC powder. First, purge the air in the reaction vessel with argon, and then perform microwave pyrolysis in an argon atmosphere to obtain the FeTi / C heterogeneous Fenton nanocatalyst.

[0011] As this embodiment, in the step (1), the molar ratio of tetrabutyl titanate to ferric nitrate is 1:1. The solvent of the tetrabutyl titanate solution is anhydrous ethanol, and the solvent of the ferric nitrate solution is deionized water.

[0012] As this embodiment, in the step (1), the mass concentration of the ammonia water solution is 10%-15%, the stirring speed is 150-180 r / min, the stirring and ultrasonic times are both 30-60 min, the stirring and ultrasonic temperatures are both 25-35 °C, the static aging time is 12-24 h, the drying temperature is 80-100 °C, the drying time is 36-48 h, and the dried FeTiO x catalyst precursor is ground into a powder with a particle size ≤ 74 μm.

[0013] As this embodiment, in the step (2), the reducing atmosphere is a mixed gas of argon and hydrogen, the volume fraction of hydrogen is 5 vol%, the balance is argon, the flow rate of the reducing atmosphere is 100-150 mL / min, the calcination temperature is 450-900 °C, the calcination time is 1 h, and more preferably, the calcination temperature is 600 °C.

[0014] As this embodiment, in the step (3), the flow rate of the argon atmosphere is 100-150 mL / min, the dechlorination treatment temperature is 350 °C, and the dechlorination treatment time is 8-10 min.

[0015] As this embodiment, in the step (4), the FeTiO x catalyst and the pretreated PVC powder are mixed in a mass ratio of 1:1, the flow rate of the argon atmosphere is 100-200 mL / min, the pyrolysis temperature is 700 °C, and the pyrolysis time is 20-40 s.

[0016] In this embodiment, the purpose of the dechlorination treatment is to remove the chlorine element contained in the PVC powder, which is beneficial to ensuring that the number of active components on the generated FeTi / C nanomaterial is sufficient and reducing FeTiO3 The content of the inactive components can better form carbon nanotubes and amorphous carbon, and play the synergistic effect of both to improve the activity and stability of the prepared heterogeneous catalyst.

[0017] The FeTi / C heterogeneous Fenton nanocatalyst is prepared by the method described in the present invention.

[0018] The application of the FeTi / C heterogeneous Fenton nanocatalyst described in the present invention in catalytic degradation of phenol in water, where the conditions are as follows: in an aqueous phenol solution with a concentration of 200 mg / L and a pH of 2.9 - 3.1, add the catalyst and H 2 O 2 solution, and the reaction temperature is 30 °C.

[0019] As a solution of this embodiment, the mass fraction of the H 2 O 2 solution is 30%, the addition amount of the catalyst is 1000 mg / L, and the addition amount of the H 2 O 2 solution is 1000 mg / L.

[0020] Compared with the prior art, what are the advantages of the present invention:

[0021] (1) The present invention uses polyvinyl chloride as the carbon source, mixes the dechlorinated polyvinyl chloride powder with the FeTiO x catalyst, and generates carbon nanotubes and amorphous carbon during microwave pyrolysis in an inert atmosphere. The generated carbon nanotubes and amorphous carbon are used as carbon carriers to load FeTi metal to obtain the FeTi / C heterogeneous Fenton nanocatalyst. This method not only provides an idea for the high-efficiency reuse of subsequent waste PVC, reduces production costs, but also is energy-saving, efficient, green and environmentally friendly.

[0022] (2) For the catalyst prepared by the present invention, the active components Fe and TiO 2 are uniformly distributed on the carbon nanotubes, having high stability and high activity. At the same time, the unique tubular structure of the carbon nanotubes in the FeTi / C heterogeneous Fenton nanocatalyst provides a good mass transfer channel, which is conducive to the rapid diffusion of phenol molecules to the inside of the catalyst to contact the active sites, thereby achieving the effect of rapid degradation of phenol.

[0023] (3) In the application system of the catalyst of the present invention for degrading phenol, the conditions are mild, the operation is simple, the degradation of phenol in industrial wastewater is achieved with a high degradation rate, no intermediate harmful substances are generated. The FeTi / C heterogeneous Fenton catalyst has a degradation rate of up to 81.94% for phenol within 10 minutes, the degradation rate can continuously reach 83.67% - 90.89%, the stability remains above 80%, and it is easy to recycle, solving the problems such as difficult recycling of the catalyst and easy secondary pollution in the traditional Fenton system. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 XRD diagrams of the FeTiO prepared for Examples 1 - 4 respectively x -450, FeTiO x -600, FeTiO x -750 and FeTiO x -900 catalysts.

[0025] Figure 2 SEM diagrams of the FeTiO prepared for Examples 1 - 4 respectively x -450, FeTiO x -600, FeTiO x -750 and FeTiO x -900 catalysts, Figure 2 (a) 100μm diagram of FeTiO x -450, Figure 2 (b) 5μm diagram of FeTiO x -450, Figure 2 (c) 300nm diagram of FeTiO x -450, Figure 2 (d) 100μm diagram of FeTiO x -600, Figure 2 (e) 5μm diagram of FeTiO x -600, Figure 2 (f) 300nm diagram of FeTiO x -600, Figure 2 (g) 100μm diagram of FeTiO x -750, Figure 2 (h) 5μm diagram of FeTiO x -750, Figure 2 (i) 300nm diagram of FeTiO x -750, Figure 2 (j) 100μm diagram of FeTiO x -900, Figure 2 (k) 5μm diagram of FeTiO x -900,Figure 2 (l) is FeTiO x The 300 nm graph of -900.

[0026] Figure 3 XRD graphs of the FeTi / C-450, FeTi / C-600, FeTi / C-750, and FeTi / C-900 heterogeneous Fenton nanocatalysts prepared in Examples 1-4 respectively.

[0027] Figure 4 SEM graphs of the FeTi / C-450, FeTi / C-600, FeTi / C-750, and FeTi / C-900 heterogeneous Fenton nanocatalysts prepared in Examples 1-4 respectively. Figure 4 (a) The 50 μm graph of FeTi / C-450. Figure 4 (b) The 2 μm graph of FeTi / C-450. Figure 4 (c) The 500 nm graph of FeTi / C-450. Figure 4 (d) The 50 μm graph of FeTi / C-600. Figure 4 (e) The 2 μm graph of FeTi / C-600. Figure 4 (f) The 500 nm graph of FeTi / C-600. Figure 4 (g) The 50 μm graph of FeTi / C-750. Figure 4 (h) The 2 μm graph of FeTi / C-750. Figure 4 (i) The 500 nm graph of FeTi / C-750. Figure 4 (j) The 50 μm graph of FeTi / C-900. Figure 4 (k) The 2 μm graph of FeTi / C-900. Figure 4 (l) The 500 nm graph of FeTi / C-900.

[0028] Figure 5 Degradation effect graphs of the heterogeneous Fenton nanocatalysts FeTi / C-450, FeTi / C-600, FeTi / C-750, and FeTi / C-900 on phenol in water in Effect Examples 1-4 respectively.

[0029] Figure 6 SEM graph of the comparative - FeTi / C-600 heterogeneous Fenton nanocatalyst prepared in the comparative example. Figure 6 (a) The 50 μm graph of the comparative - FeTi / C-600 prepared in the comparative example. Figure 6 (b) The 2 μm graph of the comparative - FeTi / C-600 prepared in the comparative example. Figure 6 (c) The 500 nm graph of the comparative - FeTi / C-600.

[0030] Figure 7 Degradation effect diagram of phenol in water by the heterogeneous Fenton nanocatalyst contrast-FeTi / C-600 prepared as a comparative example. Specific embodiments

[0031] The present invention will be further elaborated in detail through specific implementation cases below to ensure that the purpose, features and advantages of the present invention can be comprehensively and easily understood. However, the process conditions and results described in the embodiments are only used to illustrate the present invention. It should not and will not limit the present invention described in detail in the claims. Without special instructions, all experimental equipment, drugs, reagents and materials used in the present invention can be obtained from commercial channels.

[0032] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited to the content described.

[0033] Example 1

[0034] A preparation method of a FeTi / C-450 heterogeneous Fenton nanocatalyst includes the following steps:

[0035] (1) Weigh 34.032 g of tetrabutyl titanate and dissolve it in 170 mL of absolute ethanol to form solution A. Dissolve 40.4 g of Fe(NO 3 ) 3 ·9H 2 O in 100 mL of deionized water to form solution B. Add solution B to solution A to form solution C, and place solution C in a water bath at 30 °C and stir for 30 min. Then, ultrasound solution C at 30 °C for 30 min. Under the conditions of a stirring speed of 150 r / min and a stirring temperature of 30 °C, slowly drop a 10% ammonia water solution into solution C until solution C completely becomes a colloidal solid.

[0036] (2) After standing and aging the colloidal solid for 24 h, place it in a drying oven at 80 °C and dry for 48 h to obtain a FeTiO x catalyst precursor. Grind the dried FeTiO x catalyst precursor into a powder with a particle size ≤ 74 μm, and place it in a tubular furnace. Under a reduction atmosphere of a roasting temperature of 450 °C, a flow rate of 100 mL / min, a volume fraction of 5% H 2 and 95% Ar, reduce and roast for 1 h to obtain a FeTiO x -450 catalyst.

[0037] (3) Place the PVC powder in a tubular furnace and perform dechlorination pretreatment for 10 min under a pretreatment temperature of 350 °C and an argon atmosphere with a flow rate of 100 mL / min to obtain pretreated PVC with a chlorine content of only 0.41 wt.%, and grind the pretreated PVC into a powder.

[0038] (4) Mix the FeTiO x -450 catalyst and the pretreated PVC in a mass ratio of 1:1, place them in a microwave reaction vessel, first purge the reaction vessel with argon at a flow rate of 200 mL / min for 15 min to remove the air in the reaction vessel. Subsequently, turn on the microwave power of 800 W, heat up to 700 °C, and carry out microwave pyrolysis for 30 s to obtain the FeTi / C-450 heterogeneous Fenton nanocatalyst.

[0039] Example 2

[0040] A preparation method of an FeTi / C-600 heterogeneous Fenton nanocatalyst, comprising the following steps:

[0041] (1) Weigh 34.032 g of tetrabutyl titanate and dissolve it in 170 mL of absolute ethanol to form solution A. Dissolve 40.4 g of Fe(NO 3 ) 3 ·9H 2 O in 100 mL of deionized water to form solution B. Add solution B to solution A to form solution C, and place solution C in a water bath at 30 °C and stir for 30 min. Subsequently, ultrasonicate solution C for 30 min at 30 °C. Next, under the conditions of a stirring speed of 150 r / min and a stirring temperature of 30 °C, slowly drop the ammonia water solution with a mass concentration of 15% into solution C until solution C completely becomes a colloidal solid.

[0042] (2) Let the colloidal solid stand for aging for 24 h, then put it into a drying oven at 80 °C and dry for 48 h to obtain the FeTiO x catalyst precursor. Grind the dried FeTiO x catalyst precursor into a powder with a particle size ≤ 74 μm, and place it in a tubular furnace. Under a roasting temperature of 600 °C and a reducing atmosphere with a flow rate of 150 mL / min, a volume fraction of 5% H 2 and 95% Ar, perform reduction roasting for 1 h to obtain the FeTiO x -600 catalyst.

[0043] (3) Place the PVC powder in a tubular furnace and perform dechlorination pretreatment for 10 min under a pretreatment temperature of 350 °C and an argon atmosphere with a flow rate of 150 mL / min to obtain pretreated PVC with a chlorine content of only 0.41 wt.%, and grind the pretreated PVC into a powder.

[0044] (4) Mix the FeTiO x -600 catalyst and the pretreated PVC in a mass ratio of 1:1, place them in a microwave reaction vessel, first purge the reaction vessel with argon at a flow rate of 100 mL / min for 15 min to remove the air in the reaction vessel. Subsequently, turn on the microwave power of 800 W, heat up to 700 °C, and carry out microwave pyrolysis for 30 s to obtain the FeTi / C-600 heterogeneous Fenton nanocatalyst.

[0045] Example 3

[0046] A preparation method of an FeTi / C-750 heterogeneous Fenton nanocatalyst, comprising the following steps:

[0047] (1) Weigh 34.032 g of tetrabutyl titanate and dissolve it in 170 mL of absolute ethanol to form solution A. Dissolve 40.4 g of Fe(NO 3 ) 3 ·9H 2 O in 100 mL of deionized water to form solution B. Add solution B to solution A to form solution C, and place solution C in a water bath at 30 °C and stir for 30 min. Subsequently, ultrasonicate solution C for 30 min at 30 °C. Under the conditions of a stirring speed of 150 r / min and a stirring temperature of 30 °C, slowly drop a 10% ammonia water solution into solution C until solution C completely becomes a colloidal solid.

[0048] (2) Let the colloidal solid stand for aging for 24 h, then put it into an oven at 80 °C and dry for 48 h to obtain the FeTiO x catalyst precursor. Grind the dried FeTiO x catalyst precursor into a powder with a particle size ≤ 74 μm, and place it in a tubular furnace. Under a reduction roasting atmosphere of a roasting temperature of 750 °C, a flow rate of 100 mL / min, a volume fraction of 5% H 2 and 95% Ar, carry out reduction roasting for 1 h to obtain the FeTiO x -750 catalyst.

[0049] (3) Place the PVC powder in a tubular furnace, and carry out dechlorination pretreatment at a pretreatment temperature of 350 °C and an argon atmosphere with a flow rate of 100 mL / min for 10 min to obtain the pretreated PVC with a chlorine content of only 0.41 wt.%, and grind the pretreated PVC into a powder.

[0050] (4) Mix the FeTiO xThe -750 catalyst and pretreated PVC are mixed at a mass ratio of 1:1 and placed in a microwave reaction vessel. First, the reaction vessel is purged with argon at 200 mL / min for 15 min to expel the air in the reaction vessel. Subsequently, the microwave power of 800 W is turned on, and the temperature is raised to 700 °C for microwave pyrolysis for 30 s to obtain the FeTi / C-750 heterogeneous Fenton nanocatalyst.

[0051] Example 4

[0052] A preparation method of a FeTi / C-900 heterogeneous Fenton nanocatalyst includes the following steps:

[0053] (1) Weigh 34.032 g of tetrabutyl titanate and dissolve it in 170 mL of absolute ethanol to form solution A. Dissolve 40.4 g of Fe(NO 3 ) 3 ·9H 2 O in 100 mL of deionized water to form solution B. Add solution B to solution A to form solution C, and place solution C in a water bath at 30 °C and stir for 30 min. Subsequently, under the conditions of 30 °C, sonicate solution C for 30 min. Under the conditions of a stirring speed of 150 r / min and a stirring temperature of 30 °C, slowly drop the ammonia water solution with a mass concentration of 12% into solution C until solution C completely becomes a colloidal solid.

[0054] (2) After standing and aging the colloidal solid for 24 h, put it into a drying oven at 80 °C and dry for 48 h to obtain the FeTiO x catalyst precursor. Grind the dried FeTiO x catalyst precursor into a powder with a particle size ≤ 74 μm, and place it in a tubular furnace. Under the reduction roasting temperature of 900 °C and a reducing atmosphere of H 2 with a flow rate of 100 mL / min and a volume fraction of 5% and 95% Ar, perform reduction roasting for 1 h to obtain the FeTiO x -900 catalyst.

[0055] (3) Place the PVC powder in a tubular furnace and perform dechlorination pretreatment at a pretreatment temperature of 350 °C and an argon atmosphere with a flow rate of 100 mL / min for 10 min to obtain the pretreated PVC with a chlorine content of only 0.41 wt.%, and grind the pretreated PVC into a powder.

[0056] (4) Place the FeTiO xThe -900 catalyst and pretreated PVC were mixed at a mass ratio of 1:1 and placed in a microwave reaction vessel. First, the reaction vessel was purged with argon at 200 mL / min for 15 min to expel the air in the reaction vessel. Subsequently, a microwave power of 800 W was turned on, and the temperature was raised to 700 °C for microwave pyrolysis for 30 s to obtain the FeTi / C-900 heterogeneous Fenton nanocatalyst.

[0057] The FeTiO prepared in Examples 1-4 x -450, FeTiO x -600, FeTiO x -750 and FeTiO x -900 catalysts and the heterogeneous Fenton nanocatalysts FeTi / C-450, FeTi / C-600, FeTi / C-750 and FeTi / C-900 were respectively characterized by XRD and SEM. It can be seen from Figure 1 that as the reduction temperature increases, the crystallinity of the FeTiO x catalyst becomes more and more complete. The main phases of FeTiO x -450 and FeTiO x -600 are mainly FeTiO 3 and Fe 2 TiO 5 . As the reduction temperature further rises to 750 °C and 900 °C, obvious TiO 2 peaks appear. This is because the unstable Fe 2 TiO 5 decomposes into FeTiO 3 and rutile TiO 2 with increasing temperature.

[0058] From Figure 2 the SEM images of FeTiO x -450, FeTiO x -600, FeTiO x -750 and FeTiO x -900 catalysts, it can be seen that as the reduction temperature increases, the moisture and easily decomposable substances in the FeTiO x catalyst precursor are evaporated and decomposed, and the catalyst particles are continuously sintered, and the particle size and pore size of the catalyst are continuously increasing; from Figure 3It can be seen that in the XRD patterns of FeTi / C-450, FeTi / C-600, and FeTi / C-750, typical graphite carbon diffraction peaks were detected near 26°. Under the action of surface tension and axial pressure, the formation of continuous graphene layers was promoted, and finally carbon nanotubes were formed. However, the intensity of the graphite carbon diffraction peak in the XRD pattern of FeTi / C-900 was very low and almost non-existent, indicating that x when FeTiO x -900 was used for catalytic pyrolysis, almost no carbon nanotubes were generated from the pretreated PVC. This is because as the particle size of the FeTiO

[0059] From Figure 4 the SEM images of FeTi / C-450, FeTi / C-600, FeTi / C-750, and FeTi / C-900, it can be seen that the carbon products in FeTi / C-450 and FeTi / C-600 are mainly carbon nanotubes. FeTi / C-750 mainly consists of amorphous carbon and a small amount of carbon nanotubes, and FeTi / C-900 is basically composed of amorphous carbon, and no carbon nanotubes were found, which is consistent with the Figure 3 XRD results of FeTi / C-900 in

[0060] Effect Example

[0061] The heterogeneous Fenton nanocatalysts FeTi / C-450, FeTi / C-600, FeTi / C-750, and FeTi / C-900 prepared in Examples 1-4 were applied to the catalytic degradation of phenol in water. The effects are as Figure 5 shown and include the following steps:

[0062] (1) Respectively measure 100 mL of phenol solution with a concentration of 200 mg / L. After adjusting the pH value of the phenol solution to 2.9 - 3.1 using sulfuric acid solution, add 0.3 mL of 30% H 2 O 2 and FeTi / C-450, FeTi / C-600, FeTi / C-750, and FeTi / C-900 catalysts. The addition amount of H 2 O 2 is 1000 mg / L, and the addition amount of each catalyst is 1000 mg / L.

[0063] (2) Place the above reaction system in a water bath at 30 °C and stir for degradation at a stirring speed of 180 r / min. To more clearly observe the change of phenol degradation rate with degradation time, the catalytic degradation time is set to 7 groups, namely 0 min, 10 min, 20 min, 30 min, 40 min, 50 min, and 60 min.

[0064] (3) After each group of degradation experiments, adjust the pH value of the reaction system to 7 - 9 with NaOH solution and filter. Calculate the degradation rate of phenol in water by the FeTi / C-450, FeTi / C-600, FeTi / C-750, and FeTi / C-900 catalysts by measuring the concentration of phenol in the filtered solution.

[0065] According to Figure 5 It can be seen that in the application of catalytic degradation of phenol in water by the heterogeneous Fenton nanocatalysts FeTi / C-450, FeTi / C-600, FeTi / C-750, and FeTi / C-900 prepared in the present invention, the degradation rates within 60 min reach 90.89%, 88.6%, 83.67%, and 85.93% respectively, and the continuous stabilities are 85.68%, 86.02%, 80.06%, and 82.72% respectively; in the initial stage of degradation, the heterogeneous Fenton nanocatalyst FeTi / C-600 has the most significant degradation effect on phenol, and within 10 min, the degradation rate of phenol is as high as 81.94%; followed by FeTi / C-750 and FeTi / C-900, while the degradation rate of FeTi / C-450 to phenol is only 6.77% after 30 min of reaction. This is because in the FeTi / C-450 catalyst, the reduction temperature is relatively low, and the active components Fe and TiO 2 are poorly dispersed, resulting in a small number and uneven distribution of active sites on the carbon nanotubes, reducing the contact opportunity between phenol molecules and active sites and leading to poor degradation efficiency.

[0066] The FeTi / C-600 catalyst obtained by reduction roasting at 600 °C has more uniform dispersion of its active components Fe and TiO 2 After pyrolysis in mixture with pretreated PVC, the active sites are evenly distributed and the number is large on the carbon nanotubes. At the same time, due to its unique tubular structure, the carbon nanotubes in FeTi / C-600 provide a good mass transfer channel, which is conducive to the rapid diffusion of phenol molecules to the inside of the catalyst to contact with the active sites, thus achieving the effect of rapid degradation of phenol; although the active sites of FeTi / C-750 and FeTi / C-900 are evenly distributed, their carbon products are mainly aggregated spherical carbon, which limits the mass transfer channel and reduces the diffusion rate of phenol molecules to the active sites.

[0067] Therefore, when the temperature of the reduction roasting is relatively low, the generated FeTiO x catalyst has a smaller particle size. When the dechlorinated PVC powder is mixed and pyrolyzed with it, under the action of surface tension and axial pressure, it is easier to promote the formation of continuous graphene layers, and finally carbon nanotubes are formed. However, the dispersion of the active components Fe and TiO 2 is insufficient; when the reduction temperature is relatively high, the generated FeTiO x catalyst has a larger particle size, resulting in the carbon generated after the pyrolysis of dechlorinated PVC being mainly amorphous carbon, and the carbon products show an agglomeration phenomenon, resulting in relatively low activity and stability of the catalyst.

[0068] Comparative example

[0069] The difference between this example and Example 2 is that the carbon source PVC was not dechlorinated. The SEM of the prepared FeTi / C-600 catalyst is as Figure 6 shown.

[0070] From Figure 6 it can be seen that the carbon product obtained after the mixed pyrolysis of PVC without dechlorination treatment and FeTiO x -600 is dense granular amorphous carbon, and the particle size of these amorphous carbons is much smaller than that of the amorphous carbons in FeTi / C-750 and FeTi / C-900.

[0071] The FeTi / C-600 catalyst prepared in the comparative example was applied to the catalytic degradation of phenol in water. The operation steps were the same as those of the FeTi / C-450, FeTi / C-600, FeTi / C-750, and FeTi / C-900 heterogeneous Fenton nanocatalysts applied to the catalytic degradation of phenol in water in the effect example. The degradation effect is as Figure 7 shown.

[0072] According to Figure 7 it can be known that the phenol degradation rate of the FeTi / C-600 catalyst prepared in the comparative example is only 60.86% within 60 minutes, and the degradation efficiency curve has tended to be flat, indicating that the degradation efficiency will not increase significantly with the further extension of the degradation time. The degradation efficiency of phenol is much lower than that of the FeTi / C-450, FeTi / C-600, FeTi / C-750, and FeTi / C-900 heterogeneous Fenton nanocatalysts. This is because the carbon material generated after the mixed pyrolysis of PVC without dechlorination and FeTiO x -600 is granular carbon with a smaller particle size. These carbon particles are stacked and dense, affecting the diffusion rate of phenol molecules to the active sites. In addition, during the pyrolysis process, a large amount of chlorine elements in PVC will cause the inactivation of the active sites of the FeTi / C-600 catalyst, greatly reducing the number of active sites, resulting in low phenol degradation efficiency.

[0073] Combined with the above, the present invention successfully prepares the FeTi / C heterogeneous Fenton nanocatalyst. The prepared catalyst has the characteristics of high degradation efficiency for phenol, easy recovery, and reusability, and is an ideal catalyst for degrading phenol.

[0074] The above has made a detailed description of the preferred specific embodiments of the present invention. However, the present invention is not limited to the above embodiments. Any person skilled in the art within the scope of knowledge can also make various changes or equivalent substitutions without departing from the purpose of the present invention.

Claims

1. A method for preparing a FeTi / C heterogeneous Fenton nanocatalyst, characterized in that: The following steps are involved: (1) Mix the ferric nitrate solution and the tetrabutyl titanate solution, stir, and ultrasonicate, then add an ammonia solution until the mixed solution becomes a colloidal solid, stand for aging, and dry to obtain FeTiO x Catalyst precursors; (2) FeTiO x The catalyst precursor was ground into powder and calcined in a reducing atmosphere to obtain FeTiO x Catalyst, x=3-5; (3) dechlorinating the PVC powder under an argon atmosphere, and then grinding the dechlorinated PVC powder to obtain a pretreated PVC powder; (4) FeTiO x The catalyst was mixed with pretreated PVC powder and subjected to microwave pyrolysis in an argon atmosphere to obtain FeTi / C heterogeneous Fenton nanocatalyst.

2. The method for preparing the FeTi / C heterogeneous Fenton nanocatalyst according to claim 1, characterized in that: In the step (1), the molar ratio of tetrabutyl titanate to ferric nitrate is 1:1, the solvent of the tetrabutyl titanate solution is anhydrous ethanol, the solvent of the ferric nitrate solution is water, the mass concentration of the ammonia solution is 10%-15%, and the drying temperature is 80-100°C.

3. The method for preparing the FeTi / C heterogeneous Fenton nanocatalyst according to claim 1, characterized in that: In the step (2), the reducing atmosphere is a mixed gas of argon and hydrogen, wherein the volume fraction of hydrogen is 5 vol% and the balance is argon, the flow rate of the reducing atmosphere is 100-150 mL / min, and the calcination temperature is 450-900°C.

4. The method for preparing the FeTi / C heterogeneous Fenton nanocatalyst according to claim 1, characterized in that: In the step (3), the flow rate of the argon atmosphere is 100-150 mL / min, the temperature of the dechlorination treatment is 350° C., and the time of the dechlorination treatment is 8-10 min.

5. The method for preparing the FeTi / C heterogeneous Fenton nanocatalyst according to claim 1, characterized in that: In the step (4), FeTiO x The catalyst and the pretreated PVC powder were mixed in a mass ratio of 1:1, the flow rate of the argon atmosphere was 100-500 mL / min, and the temperature of the microwave pyrolysis was 700°C.

6. The method according to any one of claims 1 to 5 is used to prepare FeTi / C heterogeneous Fenton nanocatalyst.

7. Application of the FeTi / C heterogeneous Fenton nanocatalyst according to claim 6 in catalytic degradation of phenol.

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