Titanium-cobalt-nickel composite nanosheet catalyst, and preparation method therefor and use thereof

Abstract

Disclosed in the present invention is a preparation method for a titanium-cobalt-nickel composite nanosheet catalyst, which method comprises the following steps: step 1, dissolving cobalt acetate in ethylene glycol, and continuously stirring same to obtain an organic solution A; step 2, dissolving nickel acetate in ethylene glycol, and continuously stirring same to obtain an organic solution B; step 3, dissolving tetrabutyl titanate in ethylene glycol, and continuously stirring same to obtain an organic solution C; step 4, mixing the organic solution A, the organic solution B and the organic solution C, and continuously stirring same to obtain a mixed organic solution D; step 5, performing a hydrothermal reaction on the mixed organic solution D to obtain a reaction mixture E, and leaving same to stand until room temperature; step 6, after the reaction mixture E is obviously stratified, removing the upper liquid phase product, and performing a firing reaction on the bottom solid phase product; and step 7, after the firing reaction, placing the reaction product F on a steel plate for quenching to obtain a titanium-cobalt-nickel composite nanosheet catalyst sample. The catalyst prepared by means of the preparation method provided in the present invention can efficiently and stably remove pollutants in pharmaceutical wastewater.

Description

Titanium-cobalt-nickel composite nanosheet catalyst, preparation method and application thereof Technical Field

[0001] The present invention relates to the technical field of catalytic materials, and in particular to a titanium-cobalt-nickel composite nanosheet catalyst, a preparation method thereof, and an application thereof. Background Art

[0002] Pharmaceutical wastewater is characterized by high concentrations of organic pollutants, resistance to biodegradation, and high levels of toxic and hazardous substances. Most of the residual antibiotics, halogenated compounds, organic solvents, ether compounds, and nitro compounds in the wastewater are difficult to degrade, making traditional biological treatment technologies ineffective in treating this type of wastewater.

[0003] Catalytic wet oxidation (CWAO) is an advanced oxidation technology based on high-temperature, high-pressure hydrothermal reactions. In the presence of a solid catalyst, organic pollutants are oxidized into intermediates or mineralized into carbon dioxide, water, and related inorganic salts. From an environmental perspective, the use of catalytic wet oxidation (CWAO) is a promising option for removing pollutants from pharmaceutical wastewater. The development of efficient and stable catalytic materials is crucial for the application of CWAO technology. The addition of efficient catalysts can shorten the reaction time and effectively degrade organic pollutants under mild conditions.

[0004] However, most catalysts currently have problems such as high cost, limited treatment effect, and poor stability. In order to solve the above problems, the present invention is presented.

[0005] Summary of the Invention

[0006] The present invention aims to provide a titanium-cobalt-nickel composite nanosheet catalyst, a preparation method and an application thereof. The prepared catalyst can effectively remove pollutants in pharmaceutical wastewater and reduce the toxicity of the wastewater.

[0007] Based on the above problems, one of the technical solutions provided by the present invention is:

[0008] A method for preparing a titanium-cobalt-nickel composite nanosheet catalyst comprises the following steps:

[0009] Step 1: Dissolve cobalt acetate in ethylene glycol with continuous stirring to obtain an organic solution A;

[0010] Step 2: Dissolve nickel acetate in ethylene glycol with continuous stirring to obtain an organic solution B;

[0011] Step 3: Dissolve tetrabutyl titanate in ethylene glycol with continuous stirring to obtain an organic solution C;

[0012] Step 4: Mixing organic solution A, organic solution B and organic solution C, and continuously stirring to obtain a mixed organic solution D;

[0013] Step 5: Place the mixed organic solution D in a hydrothermal reactor for hydrothermal reaction to obtain a reaction mixture E, and allow to stand until it reaches room temperature;

[0014] Step 6: After the reaction mixture E is clearly separated into layers, the upper liquid phase product is removed and the solid phase product at the bottom is burned for reaction;

[0015] Step 7: After the calcination reaction, the reaction product F is directly placed on a steel plate for quenching to obtain the final titanium-cobalt-nickel composite nanosheet catalyst sample.

[0016] Furthermore, in step 1, the mass ratio of cobalt acetate to ethylene glycol is 1:10-20.

[0017] Furthermore, in step 2, the mass ratio of nickel acetate to ethylene glycol is 1:10-20.

[0018] Furthermore, in step 3, the mass ratio of tetrabutyl titanate to ethylene glycol is 1:7-12.

[0019] Furthermore, in step 4, the molar ratio of cobalt, nickel and titanium elements in the organic solution D is x:1-x:1, wherein 0.2≤x≤0.4.

[0020] Furthermore, the temperature of the hydrothermal reaction in step 5 is 140-160° C., and the reaction time is 6-8 h.

[0021] Furthermore, the temperature of the calcination reaction in step 6 is 750-850° C., and the reaction time is 6-8 hours.

[0022] Furthermore, in step 7, the temperature of the steel plate is 0° C., which is controlled by an ice-water mixture water bath.

[0023] Based on the above problems, the second technical solution provided by the present invention is:

[0024] Any one of the above preparation methods can produce a titanium-cobalt-nickel composite nanosheet catalyst.

[0025] Based on the above problems, the third technical solution provided by the present invention is:

[0026] Application of any of the above-mentioned titanium-cobalt-nickel composite nanosheet catalysts in catalytic wet oxidation treatment of pharmaceutical wastewater.

[0027] Furthermore, the COD concentration of the pharmaceutical wastewater is 30,500 to 41,000 mg / L; the temperature of the catalytic wet oxidation reaction is 150° C. to 190° C., the reaction time is 0.5 to 2.5 h, and the amount of catalyst added is 0.20 to 1.60 g / L.

[0028] Compared with the prior art, the advantages of the present invention are:

[0029] The catalyst is a composite nanosheet that is used in the catalytic wet oxidation treatment of pharmaceutical wastewater and can effectively and stably remove pollutants in the wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. The drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0031] FIG1 is a scanning electron microscopy result of the catalyst samples synthesized in Examples 1 and 2;

[0032] FIG2 is a scanning electron microscopy result of the catalyst samples synthesized in Examples 3 and 4;

[0033] FIG3 is a scanning electron microscopy result of the catalyst samples synthesized in Examples 5 and 6;

[0034] FIG4 is the X-ray diffraction results of the catalyst samples synthesized in Examples 1 and 2;

[0035] FIG5 is the X-ray diffraction results of the catalyst samples synthesized in Examples 3 and 4;

[0036] FIG6 is the X-ray diffraction results of the catalyst samples synthesized in Examples 5 and 6;

[0037] FIG7 is a flow chart of the preparation process of the present invention. DETAILED DESCRIPTION

[0038] The above scheme is further described below in conjunction with specific examples. It should be understood that these examples are used to illustrate the present invention and are not intended to limit the scope of the present invention. The implementation conditions adopted in the examples can be further adjusted according to the conditions of the specific manufacturer. The implementation conditions not specified are generally those in routine experiments.

[0039] Example 1

[0040] A method for preparing a titanium-cobalt-nickel composite nanosheet catalyst comprises the following steps:

[0041] 1) dissolving cobalt acetate in ethylene glycol and stirring continuously for 2 hours to obtain an organic solution A, wherein the mass ratio of cobalt acetate to ethylene glycol is 1:10;

[0042] 2) dissolving nickel acetate in ethylene glycol and stirring continuously for 3 hours to obtain an organic solution B, wherein the mass ratio of nickel acetate to ethylene glycol is 1:10;

[0043] 3) Dissolving tetrabutyl titanate in ethylene glycol and stirring continuously for 2 hours to obtain an organic solution C, wherein the mass ratio of tetrabutyl titanate to ethylene glycol is 1:7;

[0044] 4) Mixing organic solution A, organic solution B, and organic solution C, and stirring continuously for 2 hours to obtain a mixed organic solution D, wherein the molar ratio of cobalt, nickel, and titanium elements after mixing is 0.2:0.8:1;

[0045] 5) Place the mixed organic solution D in a hydrothermal reactor and perform a hydrothermal reaction at 140° C. for 6 h to obtain a reaction mixture E, which is then allowed to cool to room temperature;

[0046] 6) After the reaction mixture E is clearly separated into layers, the upper liquid phase product is removed and the solid phase product at the bottom is placed in a muffle furnace and calcined at 750°C for 6 hours;

[0047] 7) After the calcination reaction is completed, the reaction product F is directly placed on a steel plate for quenching. The temperature of the steel plate is controlled at 0° C. in an ice-water bath to obtain the final titanium-cobalt-nickel composite nanosheet catalyst sample. The thickness of the nanosheet is about 100 to 200 nm.

[0048] The titanium-cobalt-nickel composite nanosheet catalyst prepared in this example is used in the catalytic wet oxidation treatment of pharmaceutical wastewater. The specific procedure is as follows:

[0049] Add 0.5L of pharmaceutical wastewater to a 1.0L permanent magnet rotary stirring reactor, add a certain amount of catalyst at the same time, seal the reactor after mixing, and set the reaction temperature. When the reaction temperature rises to the set temperature, start timing and conduct a wet oxidation experiment on pharmaceutical wastewater. During the reaction, condensed water is used to cool the external accessories of the device, and oxygen is introduced into the reactor to maintain an oxygen partial pressure of 0.8MPa. After the wet oxidation reaction is completed, the device is naturally cooled to room temperature. Use a disposable syringe to take the supernatant in the reactor for filtration, and analyze the residual chemical oxygen demand (COD) in the wastewater sample. The initial COD concentration of pharmaceutical wastewater is 30 500mg / L, and the COD removal rate = (COD 反应前 -COD 反应后 )÷COD 反应前 ×100%.

[0050] Table 1 Removal effect of catalytic wet oxidation on pharmaceutical wastewater under different reaction conditions

[0051] The experimental results in Table 1 show that wet oxidation treatment of pharmaceutical wastewater without the addition of a catalyst is somewhat effective, albeit very limited. However, with the addition of a small amount of catalyst, under high-temperature excitation, electrons in the catalyst's valence band are excited to the conduction band, forming strongly reducing thermally excited electrons. Simultaneously, strongly oxidizing thermally excited holes are formed in the valence band. On the one hand, these thermally excited electrons and holes can utilize their inherent strong reducing and oxidizing properties to degrade pollutants. On the other hand, these thermally excited electrons can react with oxygen molecules to form highly reducing superoxide radicals, while the thermally excited holes can react with water molecules to form highly reducing hydroxyl radicals. The formation of superoxide and hydroxyl radicals contributes to the efficient degradation of pollutants. Ultimately, the combined action of these two mechanisms significantly improves the treatment efficiency of pharmaceutical wastewater by catalytic wet oxidation. Furthermore, the efficiency of catalytic wet oxidation increases significantly with increasing catalyst dosage.

[0052] Without the addition of a catalyst, the COD removal rate for pharmaceutical wastewater was only 18.6% at a reaction temperature of 150°C and a reaction time of 2.5 hours. When a catalyst level of 0.25 g / L was added and the reaction time was 2.5 hours, the treatment efficiency increased to 48.8%, a 30.2% increase in removal rate. When the catalyst level was increased to 0.8 g / L and the reaction time was 2.5 hours, the treatment efficiency reached 61.1%. When the catalyst level was increased to 1.6 g / L, the catalytic wet oxidation efficiency further increased to 72.2%, a 53.6% increase compared to similar conditions without the addition of a catalyst. These results demonstrate that the addition of a catalyst can significantly improve the removal rate of pharmaceutical wastewater.

[0053] Example 2

[0054] The titanium-cobalt-nickel composite nanosheet catalyst prepared in Example 1 was used in the catalytic wet oxidation treatment of pharmaceutical wastewater. The specific procedure was as follows:

[0055] Add 0.5L of pharmaceutical wastewater to a 1.0L permanent magnet rotary stirring reactor, add a certain amount of catalyst at the same time, seal the reactor after mixing, and set the reaction temperature. When the reaction temperature rises to the set temperature, start timing and conduct a wet oxidation experiment on pharmaceutical wastewater. During the reaction, condensed water is used to cool the external accessories of the device, and oxygen is introduced into the reactor to maintain an oxygen partial pressure of 0.8MPa. After the wet oxidation reaction is completed, the device is naturally cooled to room temperature. Use a disposable syringe to take the supernatant in the reactor for filtration, and analyze the residual chemical oxygen demand (COD) in the wastewater sample. The initial COD concentration of pharmaceutical wastewater is 33,480mg / L, and the COD removal rate = (COD 反应前 -COD 反应后 )÷COD 反应前 ×100%.

[0056] Table 2 Removal effect of catalytic wet oxidation on pharmaceutical wastewater under different reaction conditions

[0057] The experimental results in Table 2 show that the addition of a catalyst significantly improves the efficiency of wet oxidation treatment of pharmaceutical wastewater. For example, when no catalyst is added, the COD removal rate for pharmaceutical wastewater is 27.1% at a reaction temperature of 170°C and a reaction time of 2.5 hours. When the catalyst level is 0.3 g / L and the reaction time is 2.5 hours, the treatment efficiency increases to 58.9%, a 31.8% increase in removal rate. When the catalyst level is increased to 0.7 g / L and the reaction time is 2.5 hours, the treatment efficiency reaches 73.2%, a 46.1% increase compared to the absence of a catalyst. When the catalyst level is increased to 1.5 g / L, the catalytic wet oxidation efficiency further increases to 84.5%, a 57.4% increase compared to similar conditions without a catalyst.

[0058] Example 3

[0059] A method for preparing a titanium-cobalt-nickel composite nanosheet catalyst comprises the following steps:

[0060] 1) dissolving cobalt acetate in ethylene glycol and stirring continuously for 2 hours to obtain an organic solution A, wherein the mass ratio of cobalt acetate to ethylene glycol is 1:15;

[0061] 2) dissolving nickel acetate in ethylene glycol and stirring continuously for 3 hours to obtain an organic solution B, wherein the mass ratio of nickel acetate to ethylene glycol is 1:15;

[0062] 3) Dissolving tetrabutyl titanate in ethylene glycol and stirring continuously for 2 hours to obtain an organic solution C, wherein the mass ratio of tetrabutyl titanate to ethylene glycol is 1:10;

[0063] 4) Mixing organic solution A, organic solution B, and organic solution C, and stirring continuously for 2 hours to obtain a mixed organic solution D, wherein the molar ratio of cobalt, nickel, and titanium elements after mixing is 0.3:0.7:1;

[0064] 5) Place the mixed organic solution D in a hydrothermal reactor and perform a hydrothermal reaction at 150° C. for 7 h to obtain a reaction mixture D, which is then allowed to cool to room temperature;

[0065] 6) After the reaction mixture E is clearly separated into layers, the upper liquid phase product is removed and the solid phase product at the bottom is calcined in a muffle furnace at 800°C for 8 hours;

[0066] 7) After the calcination reaction is complete, the reaction product F is directly placed on a steel plate for quenching. The temperature of the steel plate is controlled at 0°C in an ice-water bath. This yields a final titanium-cobalt-nickel composite nanosheet catalyst sample having a thickness of approximately 100 to 200 nm.

[0067] The titanium-cobalt-nickel composite nanosheet catalyst prepared in this example is used in the catalytic wet oxidation treatment of pharmaceutical wastewater. The specific procedure is as follows:

[0068] Add 0.5L of pharmaceutical wastewater to a 1.0L permanent magnet rotary stirring reactor, add a certain amount of catalyst at the same time, seal the reactor after mixing, and set the reaction temperature. When the reaction temperature rises to the set temperature, start timing and conduct a wet oxidation experiment on pharmaceutical wastewater. During the reaction, condensed water is used to cool the external accessories of the device, and oxygen is introduced into the reactor to maintain an oxygen partial pressure of 0.8MPa. After the wet oxidation reaction is completed, the device is naturally cooled to room temperature. Use a disposable syringe to take the supernatant in the reactor and filter it, and analyze the residual chemical oxygen demand (COD) in the wastewater sample. The initial COD concentration of pharmaceutical wastewater is 36,780mg / L, and the COD removal rate = (COD 反应前 -COD 反应后 )÷COD 反应前 ×100%.

[0069] Table 3 Removal effect of catalytic wet oxidation on pharmaceutical wastewater under different reaction conditions

[0070] The experimental results in Table 3 show that the addition of a catalyst can significantly improve the treatment efficiency of wet oxidation, and the removal rate of pharmaceutical wastewater by catalytic wet oxidation increases with the increase in the amount of catalyst. When the reaction temperature is 160°C, the reaction time is 2.5 hours, and the catalyst addition amount is 0.3g / L, the removal rate of pharmaceutical wastewater by catalytic wet oxidation is 54.6%, which is 33.4% higher than the removal rate of the system without catalyst. When the reaction temperature is 160°C, the reaction time is 2.5 hours, and the catalyst addition amount is increased to 0.6g / L, the COD removal rate increases to 66.9%, which is 45.7% higher than the removal rate of the system with catalyst. When the reaction temperature is 160°C, the reaction time is 2.5 hours, and the catalyst addition amount is further increased to 1.4g / L, the removal rate of pharmaceutical wastewater by catalytic wet oxidation is 78.7%, which is 57.5% higher than the removal rate of the system without catalyst under similar conditions.

[0071] Example 4

[0072] The titanium-cobalt-nickel composite nanosheet catalyst prepared in Example 3 was used in the catalytic wet oxidation treatment of pharmaceutical wastewater. The specific procedure was as follows:

[0073] Add 0.5L of pharmaceutical wastewater to a 1.0L permanent magnet rotary stirring reactor, add a certain amount of catalyst at the same time, seal the reactor after mixing, and set the reaction temperature. When the reaction temperature rises to the set temperature, start timing and conduct a wet oxidation experiment on pharmaceutical wastewater. During the reaction, condensed water is used to cool the external accessories of the device, and oxygen is introduced into the reactor to maintain an oxygen partial pressure of 0.8MPa. After the wet oxidation reaction is completed, the device is naturally cooled to room temperature. Use a disposable syringe to take the supernatant in the reactor and filter it, and analyze the residual chemical oxygen demand (COD) in the wastewater sample. The initial COD concentration of pharmaceutical wastewater is 38-125mg / L, and the COD removal rate = (COD 反应前 -COD 反应后 )÷COD 反应前 ×100%.

[0074] Table 4 Removal effect of catalytic wet oxidation on pharmaceutical wastewater under different reaction conditions

[0075] The experimental results in Table 4 show that the catalytic wet oxidation efficiency of pharmaceutical wastewater increased significantly after the addition of a catalyst. When no catalyst was added, the reaction temperature was 180°C, the reaction time was 2.5 hours, and the COD removal rate was 32.5%. When the catalyst addition was 0.2 g / L, the reaction temperature was 180°C, and the reaction time was 2.5 hours, the COD removal rate increased significantly to 64.6%, 32.1% higher than the removal rate of the system without catalyst. When the reaction temperature was 180°C, the reaction time was 2.5 hours, and the catalyst addition was increased to 0.9 g / L, the COD removal rate increased to 86.1%, a 53.6% increase over the removal rate of the system with catalyst. When the reaction temperature was 180°C, the reaction time was 2.5 hours, and the catalyst addition was 1.5 g / L, the efficiency of catalytic wet oxidation for pharmaceutical wastewater treatment reached 92.5%, a 60% increase over the absence of a catalyst.

[0076] Example 5

[0077] A method for preparing a titanium-cobalt-nickel composite nanosheet catalyst comprises the following steps:

[0078] 1) dissolving cobalt acetate in ethylene glycol and stirring continuously for 2 hours to obtain an organic solution A, wherein the mass ratio of cobalt acetate to ethylene glycol is 1:20;

[0079] 2) dissolving nickel acetate in ethylene glycol and stirring continuously for 3 hours to obtain an organic solution B, wherein the mass ratio of nickel acetate to ethylene glycol is 1:20;

[0080] 3) Dissolving tetrabutyl titanate in ethylene glycol and stirring continuously for 2 hours to obtain an organic solution C, wherein the mass ratio of tetrabutyl titanate to ethylene glycol is 1:12;

[0081] 4) Mixing solution A, solution B, and solution C, and stirring continuously for 2 hours to obtain a mixed organic solution D, wherein the molar ratio of cobalt, nickel, and titanium elements after mixing is 0.4:0.6:1;

[0082] 5) Place the mixed organic solution D in a hydrothermal reactor and perform a hydrothermal reaction at 160° C. for 8 h to obtain a reaction mixture E, which is then allowed to cool to room temperature;

[0083] 6) After the reaction mixture E is clearly separated into layers, the upper liquid phase product is removed and the solid phase product at the bottom is placed in a muffle furnace and calcined at 850°C for 7 hours;

[0084] 7) After the calcination reaction is complete, the reaction product F is directly placed on a steel plate for quenching. The temperature of the steel plate is controlled at 0°C in an ice-water bath. This yields a final titanium-cobalt-nickel composite nanosheet catalyst sample having a thickness of approximately 100 to 200 nm.

[0085] The titanium-cobalt-nickel composite nanosheet catalyst prepared in this example is used in the catalytic wet oxidation treatment of pharmaceutical wastewater. The specific procedure is as follows:

[0086] To a 1.0L permanent magnet rotary stirred reactor, 0.5L of pharmaceutical wastewater was added, along with a predetermined amount of catalyst. After mixing, the reactor was sealed and the reaction temperature was set. When the reaction temperature reached the set temperature, a timer was started, and the wet oxidation experiment of the pharmaceutical wastewater was conducted. During the reaction, the external components of the apparatus were cooled with condensed water, and oxygen was introduced into the reactor to maintain an oxygen partial pressure of 0.8 Ma. After the wet oxidation reaction, the apparatus was naturally cooled to room temperature. The supernatant from the reactor was filtered using a disposable syringe, and the residual chemical oxygen demand (COD) in the wastewater sample was analyzed. The initial COD concentration of the pharmaceutical wastewater was 39,271 mg / L. The COD removal rate = (COD before reaction - COD after reaction) / COD before reaction × 100%.

[0087] Table 5 Removal effect of catalytic wet oxidation on pharmaceutical wastewater under different reaction conditions

[0088] The experimental results in Table 5 show that the catalytic wet oxidation treatment of pharmaceutical wastewater significantly improved after the addition of the catalyst compared to the wet oxidation system without the addition of the catalyst. When no catalyst was added, the reaction temperature was 175°C, the reaction time was 2.5 hours, and the wastewater COD removal rate was 29.1%. When the catalyst addition amount was 0.4g / L, the reaction temperature was 175°C, and the reaction time was 2.5 hours, the wastewater COD removal rate increased to 64.3%, an increase of 35.2% over the case without the addition of the catalyst. When the catalyst amount was increased to 0.9g / L, the catalytic wet oxidation treatment efficiency of pharmaceutical wastewater reached 80.4%, an increase of 51.3% over the case without the addition of the catalyst under similar conditions. When the catalyst amount was further increased to 1.6g / L, the COD removal rate further increased to 89.1%, an increase of 60% over the case without the addition of the catalyst under similar conditions.

[0089] Example 6

[0090] The titanium-cobalt-nickel composite nanosheet catalyst prepared in Example 5 was used in the catalytic wet oxidation treatment of pharmaceutical wastewater. The specific procedure was as follows:

[0091] To a 1.0L permanent magnet rotary stirred reactor, 0.5L of pharmaceutical wastewater was added, along with a predetermined amount of catalyst. After mixing, the reactor was sealed and the reaction temperature was set. When the reaction temperature reached the set temperature, a timer was started, and the wet oxidation experiment of the pharmaceutical wastewater was performed. During the reaction, the external components of the apparatus were cooled with condensed water, and oxygen was introduced into the reactor to maintain an oxygen partial pressure of 0.8 MPa. After the wet oxidation reaction, the apparatus was naturally cooled to room temperature. The supernatant from the reactor was filtered using a disposable syringe, and the residual chemical oxygen demand (COD) in the wastewater sample was analyzed. The initial COD concentration of the pharmaceutical wastewater was 41,000 mg / L. The COD removal rate = (COD before reaction - COD after reaction) / COD before reaction × 100%.

[0092] Table 6 Removal effect of catalytic wet oxidation on pharmaceutical wastewater under different reaction conditions

[0093] The experimental results in Table 6 show that the addition of a catalyst significantly improves the catalytic wet oxidation treatment efficiency of pharmaceutical wastewater compared to a wet oxidation system without a catalyst. The COD removal rate of the wastewater is significantly improved after the catalyst is added, and this rate increases with the amount of catalyst. When no catalyst was added, the reaction temperature was 190°C, and the reaction time was 2.5 hours, the COD removal rate of the wastewater was 36.1%. When the catalyst amount was 0.3g / L, the reaction temperature was 190°C, and the reaction time was 2.5 hours, the COD removal rate of the wastewater catalytic wet oxidation increased to 77.8%, an increase of 41.7% compared to the case without catalyst. When the catalyst amount was increased to 0.8g / L, the reaction temperature was 190°C, and the reaction time was 2.5 hours, the COD removal rate of the wastewater catalytic wet oxidation further increased to 92.5%, an increase of 56.4% compared to the case without catalyst. When the catalyst amount was 1.4g / L, the reaction temperature was 190°C, and the reaction time was 2.5 hours, the COD removal rate of the pharmaceutical wastewater catalytic wet oxidation was as high as 99.5%, an increase of 63.4% compared to the case without catalyst. These experimental results show that the addition of catalyst can significantly promote the wet oxidation reaction of pharmaceutical wastewater and improve the wastewater treatment effect.

[0094] In summary, in combination with FIG. 1 to FIG. 6 , it can be seen that the characteristics of the catalyst of the method for preparing the titanium-cobalt-nickel composite nanosheet catalyst of the present invention vary due to different preparation process conditions.

[0095] Figure 1 shows the catalysts prepared in Examples 1 and 2. Their microscopic morphology exhibits a nanosheet-like structure, with nanosheets ranging in size from approximately 1 μm to 3 μm and a thickness of approximately 100 nm. Figure 2 shows the catalysts prepared in Examples 3 and 4. Their microscopic morphology exhibits a nanosheet-like structure, with nanosheets ranging in size from approximately 500 nm to 5 μm and a thickness of approximately 100 nm to 200 nm. Figure 3 shows the catalysts prepared in Examples 5 and 6. Their microscopic morphology exhibits a nanosheet-like structure, with nanosheets ranging in size from approximately 1 μm to 4 μm and a thickness of approximately 100 nm.

[0096] Figure 4 shows the X-ray diffraction results of the catalyst samples prepared in Examples 1 and 2. The main diffraction peak positions (2θ / °) and crystal planes are: 24.1°(012), 32.7°(104), 35.2°(110), 40.6°(113), 49.1°(024), 53.7°(116), 62.1°(214) and 63.6°(300). Through data analysis, it can be concluded that the catalyst has an R-3 space group crystal structure with α=β=90°, γ=120°, a=b=approx. c = approx.

[0097] Figure 5 shows the X-ray diffraction results of the catalyst samples prepared in Examples 3 and 4. The main diffraction peak positions (2θ / °) and crystal planes are: 24.03°(012), 32.9°(104), 35.6°(110), 40.6°(113), 49.4°(024), 53.9°(116), 62.5°(214) and 63.9°(300). Through data analysis, it can be concluded that the catalyst has an R-3 space group crystal structure with α=β=90°, γ=120°, a=b=approx. c = approx.

[0098] Figure 6 shows the X-ray diffraction results of the catalyst samples prepared in Examples 5 and 6. The main diffraction peak positions (2θ / °) and crystal planes are: 24.02°(012), 32.9°(104), 35.6°(110), 40.7°(113), 49.4°(024), 53.8°(116), 62.2°(214) and 63.8°(300). Through data analysis, it can be concluded that the catalyst has an R-3 space group crystal structure with α=β=90°, γ=120°, a=b=approx. c = approx.

[0099] FIG7 is a process flow chart of the preparation process of the catalyst of the present invention.

[0100] The invention discloses an application of a titanium-cobalt-nickel composite nanosheet catalyst in catalytic wet oxidation treatment of pharmaceutical wastewater. The prepared catalyst has a nanosheet structure and has a pollutant removal rate of up to 99%, which can efficiently and stably reduce the pollutant concentration in pharmaceutical wastewater.

[0101] The above examples are intended only to illustrate the technical concepts and features of the present invention. Their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made in accordance with the spirit of the present invention are intended to be covered by the scope of protection of the present invention.

Claims

1. A method for preparing a titanium-cobalt-nickel composite nanosheet catalyst, characterized in that: The following steps are involved: Step 1: dissolving cobalt acetate in ethylene glycol, stirring continuously, to obtain an organic solution A; Step 2: dissolving nickel acetate in ethylene glycol with continuous stirring to obtain an organic solution B; Step 3: dissolving tetrabutyl titanate in ethylene glycol, stirring continuously, to obtain an organic solution C; Step 4: Mix the organic solution A, the organic solution B and the organic solution C, and continue stirring to obtain a mixed organic solution D; Step 5: placing the mixed organic solution D in a hydrothermal reactor for hydrothermal reaction to obtain a reaction mixture E, and allowing it to stand to room temperature; Step 6: After the reaction mixture E is clearly separated into layers, the liquid phase product on the top is removed, and the solid phase product on the bottom is burned for reaction; Step 7: After the calcination reaction, the reaction product F is placed on a steel plate for quenching to obtain the final titanium-cobalt-nickel composite nanosheet catalyst sample.

2. The method for preparing the titanium-cobalt-nickel composite nanosheet catalyst according to claim 1, characterized in that: In step 1, the mass ratio of cobalt acetate to ethylene glycol is 1:10-20.

3. The method for preparing the titanium-cobalt-nickel composite nanosheet catalyst according to claim 1, characterized in that: In step 2, the mass ratio of nickel acetate to ethylene glycol is 1:10-20.

4. The method for preparing the titanium-cobalt-nickel composite nanosheet catalyst according to claim 1, characterized in that: In step 3, the mass ratio of tetrabutyl titanate to ethylene glycol is 1:7-12.

5. The method for preparing the titanium-cobalt-nickel composite nanosheet catalyst according to claim 1, characterized in that: In step 4, the molar ratio of cobalt, nickel and titanium elements in the organic solution D is x:1-x:1, wherein 0.2≤x≤0.

4.

6. The method for preparing the titanium-cobalt-nickel composite nanosheet catalyst according to claim 1, characterized in that: The temperature of the hydrothermal reaction in step 5 is 140-160° C., and the reaction time is 6-8 hours.

7. The method for preparing the titanium-cobalt-nickel composite nanosheet catalyst according to claim 1, characterized in that: The temperature of the calcination reaction in step 6 is 750-850° C., and the reaction time is 6-8 hours.

8. The method for preparing the titanium-cobalt-nickel composite nanosheet catalyst according to claim 1, characterized in that: The temperature of the steel plate in step 7 is 0°C, which is controlled by an ice-water mixture water bath.

9. The titanium-cobalt-nickel composite nanosheet catalyst prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the titanium-cobalt-nickel composite nanosheet catalyst according to claim 9 in catalytic wet oxidation treatment of pharmaceutical wastewater.

11. The use according to claim 10, characterized in that: The COD concentration of the pharmaceutical wastewater is 30,500 to 41,000 mg / L; the temperature of the catalytic wet oxidation reaction is 150° C. to 190° C., the reaction time is 0.5 to 2.5 hours, and the amount of catalyst added is 0.20 to 1.60 g / L.

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