A cobalt-copper composite catalyst for pharmaceutical intermediate wastewater treatment and its preparation method

Abstract

The invention discloses a cobalt-copper composite catalyst for treating pharmaceutical intermediate wastewater and a preparation method thereof, belonging to the technical field of pharmaceutical intermediate wastewater treatment. The cobalt-copper composite catalyst for treating pharmaceutical intermediate wastewater prepared by the invention mainly comprises cobalt tetraoxide and copper oxide. The cobalt-copper composite catalyst also mainly comprises silicon dioxide. The cobalt-copper composite catalyst has a pH applicable range of 3 to 11 in a Fenton-like reaction. The cobalt-copper composite catalyst is used in combination with hydrogen peroxide, and the mass ratio of the cobalt-copper composite catalyst to hydrogen peroxide is 0.050:1.465 to 2.930. The cobalt-copper composite catalyst for treating pharmaceutical intermediate wastewater prepared by the invention has high catalytic activity and high stability, and can be used in a wide pH range in Fenton-like oxidation technology. In addition, the catalyst is easy to recycle and still has high catalytic performance after being reused multiple times.

Description

Technical Field

[0001] The invention relates to a cobalt-copper composite catalyst for treating pharmaceutical intermediate wastewater and a preparation method thereof. Background Art

[0002] The composition of pharmaceutical intermediate wastewater is complex, and it often contains a large amount of organic pollutants that are poorly soluble in water, poorly biodegradable, and difficult to oxidize. Its effective treatment is a major challenge in the field of environmental protection.

[0003] Fenton oxidation technology is a kind of technology based on ferrous ions (Fe 2+ ) and hydrogen peroxide (H2O2) in synergistic action, are widely used in the fields of organic pollutant degradation, wastewater treatment and environmental remediation. 2+ As a catalyst, H2O2 is activated to produce hydroxyl radicals (·OH), superoxide radicals (O2· - Various reactive oxygen species (ROS), such as sulphur dioxide (SO₂) and singlet oxygen (¹O₂), can effectively degrade organic pollutants. However, their degradation efficiency is affected by a variety of factors, including oxidant concentration, catalyst dosage, solution pH, temperature, and pollutant concentration. Fenton oxidation technology typically requires acidic conditions to be most effective, which limits its application.

[0004] To overcome the limitations of Fenton oxidation technology, Fenton-like oxidation technology has emerged. Fenton-like oxidation technology refers to the process in which transition atoms, in their low-valence state, catalyze H2O2 molecules to produce hydroxyl radicals. This is because some transition metal compounds, with the exception of Fe, have the same catalytic properties as Fe, providing a wider range of catalytic materials. However, the degradation effect of Fenton-like oxidation technology is also affected by many factors, among which the performance and stability of the catalyst are the most critical factors, and therefore has attracted widespread attention from scholars. Unlike Fenton oxidation technology, transition metal atoms exhibit different transition valence states during the reaction, which mainly depends on the metallic activity of their d-orbital electrons.

[0005] Due to the complexity of pharmaceutical intermediate wastewater, existing catalytic materials are unable to meet the degradation requirements of different pollutants, resulting in the degradation efficiency of Fenton-like oxidation technology needs to be improved. Therefore, it is crucial to develop catalysts with high catalytic properties and high stability. Highly catalytic catalysts can increase the reaction rate and more efficiently degrade organic pollutants in pharmaceutical intermediate wastewater; highly stable catalysts can ensure stable performance during the reaction process and reduce catalyst loss. In addition, if the pH value range of the application of Fenton-like oxidation technology can be expanded, its application scenarios will be greatly broadened. At the same time, in order to reduce costs and reduce secondary pollution, the catalyst should be easy to recycle and still have high catalytic performance after repeated use.

[0006] In summary, the development of a cobalt-copper composite catalyst for pharmaceutical intermediate wastewater treatment and its preparation method has important practical significance for improving the efficiency of pharmaceutical intermediate wastewater treatment and expanding the application scope of Fenton-like oxidation technology. Summary of the Invention

[0007] The purpose of the present invention is to provide a cobalt-copper composite catalyst for pharmaceutical intermediate wastewater treatment and a preparation method thereof, so as to solve the technical problems mentioned in the above background technology.

[0008] The technical solution for achieving the purpose of the present invention is:

[0009] In a first aspect, the present invention provides a cobalt-copper composite catalyst for treating pharmaceutical intermediate wastewater, wherein the main components of the cobalt-copper composite catalyst include cobalt tetraoxide and copper oxide.

[0010] Furthermore, the main component of the cobalt-copper composite catalyst also includes silicon dioxide.

[0011] Furthermore, the pH applicable range of the cobalt-copper composite catalyst in the Fenton-like oxidation reaction is 3-11; the cobalt-copper composite catalyst is used in combination with hydrogen peroxide, and the mass ratio of the cobalt-copper composite catalyst to hydrogen peroxide is 0.050:1.465-2.930; the phenol content in the pharmaceutical intermediate wastewater is 10-20 mg / L; and the usage of the cobalt-copper composite catalyst in the pharmaceutical intermediate wastewater is 0.1-0.5 g / L.

[0012] In a second aspect, a method for preparing a cobalt-copper composite catalyst for treating pharmaceutical intermediate wastewater as described in the first aspect comprises the following preparation steps:

[0013] (1) Prepare cobalt-copper solution A;

[0014] (2) Prepare alkaline solution B;

[0015] (3) Under stirring conditions, slowly add the alkaline solution B to the cobalt-copper solution A. After reacting for 4.5 to 5.5 hours, dry and calcine to obtain a cobalt-copper composite catalyst.

[0016] Furthermore, the raw material components of the cobalt-copper solution A include: water-soluble cobalt salt, water-soluble copper salt, and ultrapure water, wherein the molar ratio of cobalt atoms in the water-soluble cobalt salt to copper atoms in the water-soluble copper salt is 1:1.

[0017] The water-soluble cobalt salt includes any one of cobalt nitrate, cobalt chloride, and cobalt sulfate, or a combination of at least two of them; the water-soluble copper salt includes any one of copper nitrate, copper chloride, and copper sulfate, or a combination of at least two of them.

[0018] Furthermore, the concentrations of cobalt atoms of the water-soluble cobalt salt and copper atoms of the water-soluble copper salt in the cobalt-copper solution A are both 0.09-0.11 mol / L.

[0019] Furthermore, the alkaline solution B uses a sodium hydroxide solution of 0.029-0.031 g / mL; after the reaction in step (3) is completed, centrifugation is required for 2-4 times before drying, and the precipitate is washed with ultrapure water until the pH value of the precipitate is neutral.

[0020] Furthermore, the raw material components of the cobalt-copper solution A also include ethyl tetrasilicate and ethanol.

[0021] Furthermore, the molar volume ratio of the water-soluble cobalt salt, the water-soluble copper salt and ultrapure water is 0.3-0.36 mol / L, and the volume ratio of ultrapure water, tetraethyl silicate and ethanol is 1:0.14-0.16:3.

[0022] Furthermore, the calcination temperature is 595-605° C., and the calcination time is 175-185 min.

[0023] By adopting the above technical solution, the present invention has the following beneficial effects:

[0024] (1) The main components of the cobalt-copper composite catalyst for treating pharmaceutical intermediate wastewater of the present invention include cobalt trioxide and copper oxide. Among them, the prices of cobalt and copper are relatively low, and the chemical stability and thermal stability are good. Therefore, the cobalt-copper composite catalyst has good catalytic performance and stability. At the same time, the cobalt-copper composite catalyst of the present invention has a wide pH range when applied in the Fenton-like oxidation technology, and it has magnetism, which is convenient for recycling and secondary utilization, thereby reducing the cost of treating pharmaceutical intermediate wastewater.

[0025] (2) The main components of the cobalt-copper composite catalyst for treating pharmaceutical intermediate wastewater of the present invention include cobalt trioxide, copper oxide, and silicon oxide. It is prepared from water-soluble cobalt salt, water-soluble copper salt, and tetraethyl silicate by a sol-gel method. The introduction of the silica gel network forms a microporous core-mesoporous structure in the cobalt-copper composite catalyst, which gives the catalyst a larger specific surface area and adsorption capacity. At the same time, when the catalyst is used, the contact between the catalyst active site, the pollutants in the pharmaceutical intermediate wastewater, and the oxidant hydrogen peroxide is more complete and close, further enhancing the catalytic effect of the catalyst. At the same time, the introduction of silica forms a metal-oxygen single bond, a silicon-oxygen single bond, and a metal-silicon single bond in the catalyst, thereby increasing the structural stability of the catalyst, effectively reducing the problem of metal ion precipitation in the catalyst, and improving the cycle stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments and in conjunction with the accompanying drawings, wherein

[0027] Figure 1 The SEM image and EDS characterization spectrum of the cobalt-copper composite catalyst obtained in Preparation Method Example 1;

[0028] Figure 2 The XRD characterization pattern of the cobalt-copper composite catalyst obtained in Preparation Example 1;

[0029] Figure 3 The SEM image and EDS characterization spectrum of the cobalt-copper composite catalyst obtained in Preparation Method Example 2;

[0030] Figure 4 The XRD characterization pattern of the cobalt-copper composite catalyst obtained in Preparation Method Example 2;

[0031] Figure 5 The graphs are the degradation effect and degradation rate of phenol in application method example 1 and application method comparative examples 1 to 4;

[0032] Figure 6 The graphs are the degradation effect and degradation rate of phenol in application method example 1 and application method comparative examples 5 to 8;

[0033] Figure 7 The graphs are the degradation effect and degradation rate of phenol in application method example 4 and application method comparative examples 9 to 12;

[0034] Figure 8 This is a graph showing the degradation effect of the number of recycling times of the cobalt-copper composite catalyst obtained in Preparation Method Example 1;

[0035] Figure 9 This is a graph showing the degradation effect of the number of recycling times of the cobalt-copper composite catalyst obtained in Preparation Method Example 2;

[0036] Figure 10 SEM characterization analysis of the cobalt-copper composite catalyst obtained in Preparation Method Example 1 before (left) and after (right) reaction;

[0037] Figure 11 SEM characterization analysis of the cobalt-copper composite catalyst obtained in Preparation Method Example 2 before (left) and after (right) the reaction;

[0038] Figure 12 These are the degradation effect diagrams and degradation rate diagrams of phenol in application method example 2 and application method comparative example 3. DETAILED DESCRIPTION

[0039] In order to better understand the above technical solution, the above technical solution will be described in detail below with reference to the accompanying drawings and specific implementation methods.

[0040] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0041] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort shall fall within the scope of protection of the present invention.

[0042] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

[0043] Water-soluble cobalt salts: cobalt nitrate, analytical grade, purchased from Sinopharm Chemical Reagent Co., Ltd.

[0044] Water-soluble copper salts: copper nitrate, analytical grade, purchased from Sinopharm Chemical Reagent Co., Ltd.;

[0045] Sodium hydroxide, ammonia, ethyl tetrasilicate, ethanol, and hydrogen peroxide were all analytically pure and purchased from Sinopharm Chemical Reagent Co., Ltd.

[0046] Phenol of analytical grade was purchased from Shanghai MacLean Biochemical Technology Co., Ltd.

[0047] Preparation method example 1

[0048] (1) Weigh 10 mmol of cobalt nitrate and 10 mmol of copper nitrate and dissolve them in 100 mL of ultrapure water, which is called cobalt-copper solution A.

[0049] (2) Weigh 3 g of sodium hydroxide and dissolve it in 100 ml of ultrapure water, which is called alkaline solution B.

[0050] (3) Under stirring conditions, alkaline solution B was added dropwise to cobalt-copper solution A at a rate of 1 drop / s. Hydroxide precipitation was generated during the reaction. After 5 hours of reaction, the solution was centrifuged three times to wash the precipitate to neutrality. The precipitate was then placed in a petri dish and dried in an oven at 60°C overnight. The precipitate was then placed in a muffle furnace and calcined at 600°C for 3 hours to obtain a cobalt-copper composite catalyst. The specific surface area of ​​the cobalt-copper composite catalyst was 11.668 m 2 / g, the average pore diameter is 28.495nm, and the average pore volume is 0.087cm 3 / g.

[0051] Among them, Figure 1It can be observed that the cobalt-copper composite catalyst presents an irregular crystal structure, and the large particles are composed of numerous nano-scale small particles. EDS characterization analysis shows that the three elements of cobalt, copper and oxygen are compounded together in a uniform manner, and the mass proportion of copper is the largest. It is inferred that it plays a major role in the catalytic process. Some unique chemical bonds may be formed between the three elements, resulting in a synergistic effect, under which phenol wastewater is efficiently degraded.

[0052] Depend on Figure 2 By comparing the standard card PDF#76-1802 and the card PDF#45-0937, the cobalt oxide corresponds to the (111) crystal plane, (220) crystal plane, (311) crystal plane, and (022) crystal plane at 2θ=19.02°, 31.31°, 36.90°, and 65.34°, respectively, and the copper oxide corresponds to the (002) crystal plane, (111) crystal plane, (-202) crystal plane, and (202) crystal plane at 35.49°, 38.73°, 48.72°, and 58.33°, respectively. This shows that after calcination, the main components of the composite catalyst are cobalt oxide and copper oxide, and according to the intensity of the diffraction peak, the diffraction peak of copper oxide is significantly stronger than that of the cobalt oxide combined with copper oxide. Figure 1 SEM image analysis shows that the catalyst is granular and is composed of numerous nano-sized particles agglomerated, proving that the catalyst has uniform grains, good dispersion and crystallinity.

[0053] Preparation method example 2

[0054] (1) Weigh 10 mmol of cobalt nitrate, 10 mmol of copper nitrate, 4.5 mL of ethyl tetrasilicate, 90 mL of ethanol, and 30 mL of ultrapure water and mix them evenly, which is recorded as cobalt-copper solution A.

[0055] (2) Weigh 20 mL of 30 wt% ammonia water and record it as alkaline solution B;

[0056] (3) Under stirring conditions, alkaline solution B was added dropwise to cobalt-copper solution A at a rate of 1 drop / s. After reacting for 5 h, the solution was placed in a petri dish and dried in an oven at 60°C until a gel was formed. The solution was then placed in a muffle furnace and calcined at 600°C for 3 h to obtain a cobalt-copper composite catalyst. The specific surface area of ​​the cobalt-copper composite catalyst was 141.259 m 2 / g, the average pore diameter is 6.311nm, and the average pore volume is 0.223cm 3 / g; compared with the cobalt-copper composite catalyst of Example 1, the specific surface area of ​​the cobalt-copper composite catalyst of Example 2 is expanded by 14 times, which greatly improves the catalytic performance; combined with its pore size distribution, the cobalt-copper composite catalyst is mostly mesoporous, which indicates that this is a mesoporous material with certain mesoporous adsorption, but also has a small amount of micropores and a small amount of microporous adsorption, which provides sufficient surface active sites for the catalytic reaction and is more suitable for treating organic pollutants with larger molecular sizes.

[0057] Depend on Figure 3 It can be observed that the cobalt-copper composite catalyst presents an irregular crystal structure, and the large particles are composed of numerous nano-scale small particles. EDS characterization analysis shows that the three elements Co, Cu, and O are compounded together in a uniform manner, and the mass proportion of the Cu element is the largest. It is inferred that it plays a major role in the catalytic process, and some unique chemical bonds may be formed between the three elements, resulting in a synergistic effect, under which phenol wastewater is efficiently degraded.

[0058] Observation Figure 4 By comparing with the standard cards PDF#42-1467, PDF#44-0706 and PDF#52-0784, the cobalt oxide corresponds to the (311) crystal plane, (511) crystal plane and (440) crystal plane at 2θ=36.85°, 59.35° and 65.23°, respectively; the copper oxide corresponds to the (002) crystal plane and (111) crystal plane at 35.24° and 38.47°, respectively; and the silicon dioxide corresponds to the (214) crystal plane at 31.58°; indicating that after calcination, the main components of the composite catalyst are cobalt oxide, copper oxide and silicon dioxide. According to the intensity of the diffraction peak, the diffraction peak of copper oxide is significantly stronger than that of cobalt oxide, which is consistent with the EDS characterization. Combined with SEM image analysis, the catalyst is granular and is composed of many nano-sized small particles agglomerated, which proves that the catalyst has uniform grains, good dispersion and crystallinity.

[0059] Application method embodiment 1

[0060] 50 mg of the cobalt-copper composite catalyst prepared in Preparation Method Example 1 and 1 mL of hydrogen peroxide were weighed and added to 100 mL of a phenol solution with a pH of 7 and a concentration of 10 mg / L under normal temperature and pressure and mechanical stirring at 250 rpm. The solution was first adsorbed for 20 minutes, and then samples were taken every 10 minutes during the reaction, with 1.5 mL sampled each time. The samples were filtered through a 2.5-μm water membrane. A total of 6 water samples were taken and the degradation effect and degradation rate of phenol were quantitatively analyzed using high-performance liquid chromatography.

[0061] Application method embodiment 2

[0062] 40 mg of the cobalt-copper composite catalyst prepared in Preparation Method Example 1 and 1 mL of hydrogen peroxide were weighed and added to 100 mL of a phenol solution with a pH of 7 and a concentration of 10 mg / L under normal temperature and pressure and mechanical stirring at 300 rpm. The mixture was first adsorbed for 20 minutes, and then samples were taken every 10 minutes during the reaction, with 1.5 mL sampled each time. The samples were filtered through a 2.5-micron water membrane. A total of 6 water samples were taken and the degradation effect and degradation rate of phenol were quantitatively analyzed using high-performance liquid chromatography.

[0063] Application method example 3

[0064] 40 mg of the cobalt-copper composite catalyst prepared in Preparation Method Example 2 and 1 mL of hydrogen peroxide were weighed and added to 100 mL of a phenol solution with a pH of 7 and a concentration of 10 mg / L under normal temperature and pressure and mechanical stirring at 300 rpm. The mixture was first adsorbed for 20 minutes, and then samples were taken every 10 minutes during the reaction, with 1.5 mL sampled each time. The samples were filtered through a 2.5-micron water membrane. A total of 6 water samples were taken and the degradation effect and degradation rate of phenol were quantitatively analyzed using high-performance liquid chromatography.

[0065] Application method example 4

[0066] 50 mg of the cobalt-copper composite catalyst prepared in Preparation Example 2 and 1 mL of hydrogen peroxide were weighed and added to 100 mL of a phenol solution with a pH of 7 and a concentration of 20 mg / L under normal temperature and pressure and mechanical stirring at 300 rpm. The mixture was first adsorbed for 20 minutes, and then samples were taken every 10 minutes during the reaction, with 1.5 mL sampled each time. The samples were filtered through a 2.5-μm water membrane. A total of 6 water samples were taken and the degradation effect and degradation rate of phenol were quantitatively analyzed using high-performance liquid chromatography.

[0067] Application method comparative example 1

[0068] The difference between Comparative Example 1 and Example 1 is that only hydrogen peroxide is added to the phenol solution for degradation. The specific steps are as follows: under normal temperature and pressure and mechanical stirring at 250 rpm, 1.5 mL of hydrogen peroxide is added to 100 mL of a phenol solution with a pH of 7 and a concentration of 10 mg / L, and adsorbed for 20 minutes. Then, during the reaction period, samples are taken every 10 minutes, with 1.5 mL sampled each time. The samples are filtered using a 2.5-micron water membrane. A total of 6 water samples are taken, and the degradation effect and degradation rate of phenol are quantitatively analyzed using high-performance liquid chromatography.

[0069] Application method comparative example 2

[0070] The difference between Comparative Example 2 and Example 1 is that only the cobalt-copper composite catalyst prepared by Preparation Method Example 1 is added to the phenol solution for degradation. The specific steps are as follows: under normal temperature and pressure and mechanical stirring at 250 rpm, 50 mg of the cobalt-copper composite catalyst prepared by Preparation Method Example 1 is added to 100 mL of a phenol solution with a pH of 7 and a concentration of 10 mg / L, and adsorbed for 20 minutes. Then, samples are taken every 10 minutes during the reaction, with 1.5 mL sampled each time. The samples are filtered using a 2.5-micron water membrane. A total of 6 water samples are taken and the degradation effect and degradation rate of phenol are quantitatively analyzed using high-performance liquid chromatography.

[0071] Application method comparative example 3

[0072] The difference between Comparative Example 3 and Example 1 is that cobalt tetroxide and hydrogen peroxide are added to the phenol solution for degradation. The specific steps are as follows: under normal temperature and pressure and mechanical stirring at 250 rpm, 50 mg of cobalt tetroxide is added to 100 mL of a phenol solution with a pH of 7 and a concentration of 10 mg / L. The solution is first adsorbed for 20 minutes, and then samples are taken every 10 minutes during the reaction, with 1.5 mL sampled each time. The samples are filtered using a 2.5-micron water membrane. A total of 6 water samples are taken and the degradation effect and degradation rate of phenol are quantitatively analyzed using high-performance liquid chromatography.

[0073] Application method comparative example 4

[0074] The difference between Comparative Example 4 and Example 1 is that copper oxide and hydrogen peroxide are added to the phenol solution for degradation. The specific steps are as follows: under normal temperature and pressure and mechanical stirring at 250 rpm, 50 mg of copper oxide is added to 100 mL of a phenol solution with a pH of 7 and a concentration of 10 mg / L, and adsorbed for 20 minutes. Then, during the reaction period, samples are taken every 10 minutes, with each sample of 1.5 mL being taken. The samples are filtered using a 2.5-micron water membrane. A total of 6 water samples are taken and the degradation effect and degradation rate of phenol are quantitatively analyzed using high-performance liquid chromatography.

[0075] Application Method Comparative Examples 5 to 8

[0076] The difference between Comparative Examples 5 to 8 and Example 1 of the application method is that the pH of the phenol solution is 3, 5, 9, and 11, respectively, and the remaining steps and ingredients are the same.

[0077] Application Method Comparative Examples 9-12

[0078] The difference between Comparative Examples 9 to 12 and Example 4 is that the pH of the phenol solution is 3, 5, 9, and 11, respectively, and the remaining steps and ingredients are the same.

[0079] Effect Examples

[0080] Catalytic: Figure 5 It can be seen that when hydrogen peroxide is used alone in Application Method Comparative Example 1, the removal rate increases slowly over time, and the removal rate is still less than 20% after 80 minutes of reaction; the removal rate of the cobalt-copper composite catalyst prepared by Preparation Method Example 1 alone in Application Method Comparative Example 2 is almost zero, and it can be inferred that these two methods are not effective in removing pollutants when used alone; Application Method Comparative Examples 3 and 4 respectively use hydrogen peroxide and cobalt tetraoxide or hydrogen peroxide and copper oxide in combination, and the removal rate of phenol is significantly improved when used; Application Method Example 1 is a combination of the cobalt-copper composite catalyst prepared by Preparation Method Example 1 and hydrogen peroxide, i.e., Co / Cu+H2O2, which shows the best removal effect, and the removal rate reaches 86.8% after 80 minutes of reaction; Figure 12 It can be seen that the cobalt-copper composite catalysts in Application Method Example 2 and Application Method Example 3 have a degradation effect of only about 60% of the cobalt-copper composite catalyst prepared by Preparation Method Example 1. After the introduction of silica, the catalytic effect of the cobalt-copper composite catalyst prepared by Preparation Method Example 2 is greatly improved. After 80 minutes of reaction, the phenol in the simulated wastewater has been completely removed.

[0081] The pH range when Fenton-like oxidation technology is applied is: Figure 6 It can be seen that the cobalt-copper composite catalyst prepared in Example 1 of the preparation method maintains high catalytic activity in the Fenton-like oxidation reaction in the pH range of 3-11, and the phenol removal rate can reach 86.8%, breaking through the pH limit of the traditional Fenton reaction; Figure 7 It can be seen that the cobalt-copper composite catalyst prepared in Example 2 of the preparation method has a slightly decreased phenol removal rate after 80 minutes of reaction under acidic conditions of pH 3 to 5, indicating that the acidic environment has a certain inhibitory effect on the activity of the cobalt-copper composite catalyst prepared in Example 2 of the preparation method, but the effect is not significant; when the pH value is increased to 11, the phenol removal rate is slightly improved. This is because the alkaline environment changes the redox potential. Taking the hydrogen electrode as a reference, the redox potential of OH / H2O2 in an alkaline environment is relatively low, thereby enhancing the activity of the catalyst; although this difference is relatively weak, it is sufficient to illustrate that the cobalt-copper composite catalyst prepared in Example 2 of the preparation method has higher activity under alkaline conditions. The cobalt-copper composite catalyst prepared in Example 2 of the preparation method can maintain high catalytic activity in a wide range of pH = 3 to 11, that is, the phenol removal rate can reach 92.3%, successfully breaking through the pH value limit of the traditional Fenton reaction.

[0082] Reuse experiment: 50 mg of the cobalt-copper composite catalyst prepared in Preparation Example 1 or Preparation Example 2 and 1.5 mL of hydrogen peroxide were weighed and added to 100 mL of a phenol solution with a pH of 7 and a concentration of 20 mg / L under normal temperature and pressure and mechanical stirring at 250 rpm. The mixture was first adsorbed for 20 minutes and then stirred for 80 minutes. After each reaction cycle, the reaction solution was centrifuged 3 times at 3000 rpm to ensure that the cobalt-copper composite catalyst was thoroughly cleaned, and then dried. This cycle was repeated 7 times to determine the removal effect of phenol after each cycle. Figures 8 and 9 It can be seen that the cobalt-copper composite catalyst prepared in Preparation Method Example 1 or Preparation Method Example 2 can still achieve 80% of the original removal rate after 7 cycles, and has good reusability.

[0083] Reaction stability: Figure 10 and Figure 11 It can be clearly seen that the microscopic morphology of the cobalt-copper composite catalysts prepared in Preparation Method Example 1 and Preparation Method Example 2 before and after the reaction does not change much and remains almost consistent. The cobalt-copper composite catalysts prepared in Preparation Method Example 1 and Preparation Method Example 2 have excellent stability.

[0084] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a cobalt-copper composite catalyst for treating pharmaceutical intermediate wastewater, characterized in that: The method comprises the following preparation steps: (1) preparing a cobalt-copper solution A; the raw material components of the cobalt-copper solution A include: a water-soluble cobalt salt, a water-soluble copper salt, and ultrapure water; the concentrations of the cobalt atoms of the water-soluble cobalt salt and the copper atoms of the water-soluble copper salt in the cobalt-copper solution A are both 0.09 to 0.11 mol / L; (2) preparing an alkaline solution B; the alkaline solution B is a 0.029-0.031 g / mL sodium hydroxide solution; the volume ratio of the alkaline solution B to the ultrapure water in the cobalt-copper solution A is 0.9-1.1:1; (3) Under stirring conditions, slowly add the alkaline solution B dropwise to the cobalt-copper solution A, react for 4.5 to 5.5 hours, dry, and calcine to obtain a cobalt-copper composite catalyst; the calcination temperature is 595 to 605°C, and the calcination time is 175 to 185 minutes.

2. The method for preparing a cobalt-copper composite catalyst for treating pharmaceutical intermediate wastewater according to claim 1, wherein: The molar ratio of the cobalt atoms in the water-soluble cobalt salt to the copper atoms in the water-soluble copper salt is 1:

1.

3. The method for preparing a cobalt-copper composite catalyst for treating pharmaceutical intermediate wastewater according to claim 1, wherein: After the reaction in step (3) is completed, the mixture needs to be centrifuged 2 to 4 times before drying, and washed with ultrapure water until the pH of the precipitate is neutral.

4. The method for preparing a cobalt-copper composite catalyst for treating pharmaceutical intermediate wastewater according to claim 1, wherein: The raw material components of the cobalt-copper solution A also include ethyl tetrasilicate and ethanol; the molar volume ratio of the water-soluble cobalt salt, water-soluble copper salt and ultrapure water is 0.3-0.36 mol / L, and the volume ratio of ultrapure water, tetraethyl silicate and ethanol is 1:0.14-0.16:

3.

5. The method for preparing a cobalt-copper composite catalyst for treating pharmaceutical intermediate wastewater according to claim 4, wherein: The alkaline solution B is a 30 wt% ammonia solution; the volume ratio of the alkaline solution B to the ultrapure water in the cobalt-copper solution A is 1.9-2.1:

3.

6. The method for preparing a cobalt-copper composite catalyst for treating pharmaceutical intermediate wastewater according to any one of claims 1 to 5, wherein: The pH applicable range of the cobalt-copper composite catalyst in the Fenton-like oxidation reaction is 3-11; the cobalt-copper composite catalyst is used in combination with hydrogen peroxide, and the mass ratio of the cobalt-copper composite catalyst to hydrogen peroxide is 0.050:1.465-2.930; the phenol content in the pharmaceutical intermediate wastewater is 10-40 mg / L; and the usage of the cobalt-copper composite catalyst in the pharmaceutical intermediate wastewater is 0.1-0.5 g / L.

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