A Cu-CaO@SiO2 core-shell catalyst for extracting calcium silicate from waste stone powder, its preparation method and application

Abstract

A core-shell catalyst for extracting calcium silicate from waste stone powder, its preparation method and application, which relate to the technical field of water treatment materials. It aims to solve the problems of unstable CuO core, easy leaching of metal ions, easy agglomeration, no catalytic activity of CaO and easy corrosion in the existing catalysts. In the present invention, silicon dioxide and calcium carbonate are extracted from construction waste stone powder as raw materials to prepare a Cu-CaO@SiO2 core-shell catalyst. CuO is loaded onto CaO by the impregnation method, and a SiO2 outer shell is wrapped outside the catalyst, so as to obtain a Cu-CaO@SiO2 core-shell catalyst in which CuO provides active sites, SiO2 serves as a protective shell, and CaO serves as a cross-linking agent to enhance the interaction between the active metal and the protective shell. The catalyst of the present invention has stronger catalytic activity, the active sites are not easily deactivated, the ion leaching rate is low, which is beneficial to the adsorption of ozone molecules and organic pollutants on the catalyst surface, and at the same time promotes the generation of active free radicals and improves the catalytic performance.

Description

Technical Field

[0001] The present invention relates to the technical field of water treatment materials, and in particular, to a core-shell catalyst for extracting calcium silicate from waste stone powder, a preparation method thereof, and an application thereof. Background Art

[0002] During the processing of building stones, a large amount of waste stone powder is generated due to processes such as cutting, polishing, and grinding. The waste stone powder is mainly divided into waste granite stone powder and waste marble stone powder. Among them, the waste granite stone powder is mainly composed of silicon dioxide (SiO2), and the waste marble stone powder is mainly composed of calcium carbonate (CaCO3). The random stacking of waste stone powder occupies arable land, is prone to generate dust, pollutes the atmosphere, and is likely to cause alveolar dust accumulation in the human body after being inhaled, threatening human health. Due to the fine particles of stone powder, it is extremely easy to form a hard crust when encountering water, affecting plant growth, and the ecological environment has been severely damaged. At present, the recycling of waste stone powder is mainly used as components of cement, concrete, building fillers, etc. These products have low prices and low added values. How to achieve high-value utilization of waste stone powder is still a great challenge. Using waste stone powder as a raw material to prepare a catalyst for catalytic ozonation degradation of antibiotics provides a new idea for the resource utilization of waste stone powder.

[0003] Antibiotics cannot be completely absorbed after entering the organism. The unabsorbed antibiotics are excreted from the body in the form of the parent compound, enter the water environment, and pollute the water body, seriously threatening the health of the aquatic ecosystem. Therefore, it is necessary to remove these antibiotics. The catalytic ozonation technology has the characteristics of fast reaction speed, mild reaction conditions, and high treatment efficiency, and has become the main method for removing refractory pollutants. The key to the catalytic ozonation technology is to develop an efficient catalyst. CuO itself has a unique spherical nanostructure and excellent mass transfer performance, and has advantages such as economy, low toxicity, and good catalytic activity, and is widely used in the catalytic ozonation process. However, Cu 2+ is easily leached from the surface of CuO particles. The calcium-based catalyst contains strong basic sites, forms an alkaline environment in the reaction system, promotes the generation of active free radicals, and calcium ions will not cause pollution in the reaction system, which is a green and environmentally friendly material. However, CaO has no catalytic activity, is easy to corrode, and there is little research on calcium-based catalysts in the catalytic ozonation technology. Summary of the Invention

[0004] The technical problems to be solved by the present invention are:

[0005] The existing catalysts have problems such as unstable CuO core, easy leaching of metal ions, easy agglomeration, and no catalytic activity and easy corrosion of CaO.

[0006] The technical solutions adopted by the present invention to solve the above technical problems are:

[0007] The present invention provides a method for preparing a Cu-CaO@SiO2 core-shell catalyst for extracting calcium silicate from waste stone powder, comprising the following steps:

[0008] I. Extracting solid A: Using construction waste stone powder as a raw material, adding an excessive amount of acidic solution to the waste stone powder for full reaction, filtering, and taking the supernatant to obtain solution B; washing and drying the precipitate to obtain solid A;

[0009] II. Extracting solid C: Adding a precipitating agent to the solution B to consume the excess acidic solution to form a precipitate, washing and drying the precipitate to obtain solid C;

[0010] III. Preparing solution D: Adding the solid A to the alkaline solution M, heating until the solid dissolves, and filtering to obtain solution D;

[0011] IV. Preparing a precursor: Adding the solid C obtained in step II to an organic solvent, performing ultrasonic dispersion, then adding an inorganic copper source and a surfactant, stirring, adding the alkaline solution M to adjust the pH value to alkaline, stirring and standing to obtain a mixed solution, subjecting the mixed solution to a hydrothermal reaction, and washing and drying the reaction product to obtain a catalyst precursor; the molar ratio of the solid C to the inorganic copper source is 50:(5 - 1).

[0012] V. Preparing the catalyst: Adding the catalyst precursor to the solution D, adding a crosslinking agent, fully stirring, adding an acidic solution to adjust the pH value to weakly acidic to form a gel, and stirring to make the gel fully wrap and age, and obtaining the Cu-CaO@SiO2 core-shell catalyst through washing, drying, and calcination.

[0013] Further, the acidic solution in step I is one of hydrochloric acid, nitric acid, sulfuric acid, or oxalic acid solution.

[0014] Further, the inorganic copper source in step IV is one of copper nitrate, copper acetate, copper chloride, or copper sulfate, and the surfactant is one of polyvinylpyrrolidone or cetyltrimethylammonium bromide.

[0015] Further, the crosslinking agent in step V is polyvinylpyrrolidone.

[0016] Further, the stirring time in step IV is not less than 5 h, and the standing time is not less than 4 h.

[0017] Further, the conditions of the hydrothermal reaction in step IV are: the temperature is 160 - 200 °C, and the time is 10 h to 18 h.

[0018] Further, the conditions for gel stirring in step V are: stirring at 50 - 70 °C for 2 - 4 h, and the aging time is 2 - 4 h.

[0019] Further, the calcination conditions in step five are: 700 - 900 °C, 4 - 6 h.

[0020] The present invention provides a core - shell catalyst, and the chemical formula of the core - shell catalyst is Cu - CaO@SiO2, which is prepared by the method described in the above technical solution.

[0021] The present invention provides an application of a core - shell catalyst for extracting calcium silicate from waste stone powder. The Cu - CaO@SiO2 core - shell catalyst for extracting calcium silicate from waste stone powder is used as a catalyst and is combined with ozone for treating phenol organic wastewater.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] First, the present invention extracts silica and calcium carbonate from construction waste stone powder as raw materials to prepare a Cu - CaO@SiO2 core - shell catalyst. CuO is loaded onto CaO by an impregnation method, and a layer of SiO2 shell is wrapped outside the catalyst, thus obtaining a Cu - CaO@SiO2 core - shell catalyst in which CuO provides active sites, SiO2 serves as a protective shell, and CaO serves as a cross - linker to enhance the interaction between the active metal and the protective shell. The catalyst of the present invention has stronger catalytic activity, the active sites are not easily inactivated, the ion leaching rate is low, which is conducive to the adsorption of ozone molecules and organic pollutants on the catalyst surface, and at the same time promotes the generation of active free radicals, improving the catalytic performance.

[0024] Second, the catalyst of the present invention has high mechanical strength, stable structure, good dispersibility, strong electron transfer ability, excellent effect in catalytic ozonation of phenol wastewater, the catalyst is easy to separate and recycle, without secondary pollution, and is suitable for the advanced treatment of antibiotic wastewater.

[0025] Third, the raw materials of the catalyst are widely sourced and inexpensive, and the resource utilization of waste stone powder can be realized. Moreover, the preparation method of the catalyst is simple and the operation is safe. Description of the Drawings

[0026] Figure 1 It is a schematic diagram of the electron transfer process of the Cu - CaO@SiO2 crystal catalytic reaction in the embodiment of the present invention;

[0027] Figure 2 It is a scanning electron microscope image of the Cu - CaO@SiO2 core - shell catalyst in the embodiment of the present invention;

[0028] Figure 3 It is a pore size distribution diagram of Cu - CaO@SiO2 in the embodiment of the present invention;

[0029] Figure 4 It is an XRD detection spectrum diagram of the catalyst in the embodiment of the present invention;

[0030] Figure 5 This is the XPS spectrum of Cu element in the embodiments of the present invention. Among them, Figure A represents the XPS spectrum of the CuO@SiO2 catalyst obtained in Comparative Example 1, and Figure B represents the XPS spectrum of Cu element of the Cu-CaO@SiO2 core-shell catalyst obtained in Example 1;

[0031] Figure 6 This is the degradation curve of phenol wastewater in the embodiments of the present invention. Detailed implementation manners

[0032] In order to enable those skilled in the art to better understand the solution of the present invention, the exemplary embodiments or examples of the present invention will be described below with reference to the accompanying drawings. Obviously, the described embodiments or examples are only part of the embodiments or examples of the present invention, rather than all of them. All other embodiments or examples obtained by those of ordinary skill in the art based on the embodiments or examples in the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0033] To make the above objects, features and advantages of the present invention more obvious and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0034] In a typical embodiment of the present invention, a preparation method of a Cu-CaO@SiO2 core-shell catalyst for extracting calcium silicate from waste stone powder is provided, including the following steps:

[0035] I. Extracting solid A: Using construction waste stone powder as the raw material, adding an excessive amount of acidic solution to the waste stone powder to react fully, filtering, and taking the supernatant to obtain solution B; washing and drying the precipitate to obtain solid A;

[0036] II. Extracting solid C: Adding a precipitant to the solution B to consume the excess acidic solution to generate a precipitate, washing and drying the precipitate to obtain solid C;

[0037] III. Preparing solution D: Adding the solid A to the alkaline solution M, heating until the solid dissolves, and filtering to obtain solution D;

[0038] IV. Preparing the precursor: Adding the solid C obtained in step II to an organic solvent, performing ultrasonic dispersion, then adding an inorganic copper source and a surfactant, stirring, adding the alkaline solution M to adjust the pH value to alkaline, stirring and standing to obtain a mixed solution, performing a hydrothermal reaction on the mixed solution, and washing and drying the reaction product to obtain the catalyst precursor; the molar ratio of solid C to the inorganic copper source is 50:(5 - 1).

[0039] V. Preparation of catalyst: Add the catalyst precursor into solution D, add a crosslinking agent, stir well, add an acidic solution to adjust the pH value to weakly acidic to form a gel, and make the gel fully wrap and age through stirring, and obtain the Cu-CaO@SiO2 core-shell catalyst through washing, drying, and calcination.

[0040] In this embodiment, CuO is impregnated on CaO to prepare a bimetallic catalyst, and a SiO2 shell is coated outside the catalyst core to protect the Cu-CaO catalyst and reduce the leaching of metal ions. Calcium oxide forms an alkaline environment in the reaction system to promote the degradation of pollutants.

[0041] In a typical embodiment of the present invention, the acidic solution in step one is preferably one of hydrochloric acid, nitric acid, sulfuric acid, or oxalic acid solution. Hydrochloric acid, nitric acid, and sulfuric acid are all strongly acidic. Considering safety, hydrochloric acid is preferred. Oxalic acid has good safety but relatively weak acidity.

[0042] In a typical embodiment of the present invention, the precipitating agent in step two is preferably one of sodium carbonate, potassium carbonate, sodium sulfate, or potassium sulfate, and the precipitating agent is added until the pH of the solution is 7.

[0043] In a typical embodiment of the present invention, the alkaline solution M is preferably one of sodium hydroxide solution, sodium carbonate solution, sodium bicarbonate solution, or ammonia water.

[0044] In a typical embodiment of the present invention, the inorganic copper source in step four is preferably one of copper nitrate, copper acetate, copper chloride, or copper sulfate, and the surfactant is preferably one of polyvinylpyrrolidone or cetyltrimethylammonium bromide.

[0045] In a typical embodiment of the present invention, the crosslinking agent in step five is preferably polyvinylpyrrolidone. Adding polyvinylpyrrolidone as a crosslinking agent in solution D promotes the formation of SiO2 gel, making it better wrap on the catalyst surface as a shell to protect the catalyst.

[0046] In a typical embodiment of the present invention, the stirring time in step four is preferably not less than 5 h, and the standing time is preferably not less than 4 h.

[0047] In a typical embodiment of the present invention, the conditions of the hydrothermal reaction in step four are preferably: the temperature is 160 - 200 °C, and the time is 10 h - 18 h.

[0048] In a typical embodiment of the present invention, the conditions for gel stirring in step five are preferably: stirring at 50 - 70 °C for 2 - 4 h, and the aging time is 2 - 4 h.

[0049] In a typical embodiment of the present invention, the conditions for calcination in step five are preferably: 700 - 900 °C, 4 - 6 h.

[0050] In another typical embodiment of the present invention, a core - shell catalyst is further provided. The chemical formula of the core - shell catalyst is Cu - CaO@SiO2 and it is prepared by the above - mentioned method.

[0051] In another typical embodiment of the present invention, an application of the core - shell catalyst for extracting calcium silicate from waste stone powder is further provided. The Cu - CaO@SiO2 core - shell catalyst for extracting calcium silicate from waste stone powder is used as a catalyst and is combined with ozone for treating phenol organic wastewater.

[0052] Example 1

[0053] A method for preparing a Cu - CaO@SiO2 core - shell catalyst for extracting calcium silicate from waste stone powder, comprising the following steps:

[0054] I. Extracting solid A: Using construction waste stone powder as raw material, adding an excessive amount of hydrochloric acid with a concentration of 1.8 mol / L to 20 g of waste stone powder to dissolve soluble substances. After sufficient reaction, taking the supernatant and filtering to obtain solution B; the remaining precipitate is washed and dried thoroughly to obtain solid A (mainly composed of silicon dioxide);

[0055] II. Extracting solid C: Adding sodium carbonate to the solution B obtained in step I. After consuming the excess acidic solution, a precipitate appears. Continuing to add sodium carbonate until the pH of the solution is 7 to obtain a precipitate. The precipitate is washed and dried to obtain solid C (mainly composed of calcium carbonate);

[0056] III. Preparing solution D: Adding the solid A obtained in step I to sodium hydroxide solution, heating to dissolve the solid at a temperature of 80 °C, and filtering to obtain solution D;

[0057] IV. Preparing the precursor: Adding 2 g of the extracted solid C to 100 mL of absolute ethanol, ultrasonically dispersing for 30 min, adding 1 mmol of copper nitrate and 0.05 g of polyvinylpyrrolidone. After complete dissolution, stirring in a water bath at 45 °C, adding 1 mol / L ammonia water solution to adjust the pH value to 9 - 10, stirring for 5 h and standing for 4 h. Hydrothermal reaction is carried out at 180 °C for 12 h. The reaction product is washed alternately with ethanol and deionized water 3 times and dried at 70 °C for 6 h to obtain the catalyst precursor;

[0058] V. Preparation of catalyst: The prepared catalyst precursor was added to Solution D, 0.1 g of polyvinylpyrrolidone was added, and after sufficient stirring, hydrochloric acid was added to form a gel. The gel was stirred at 60 °C for 3 h to ensure complete encapsulation, and then left to age for 3 h. It was washed alternately with ethanol and deionized water three times, dried at 70 °C for 6 h, and calcined at 800 °C for 5 h to obtain the Cu-CaO@SiO2 core-shell catalyst.

[0059] Example 2

[0060] The difference between this example and Example 1 is that

[0061] In step 4, 2 mmol of copper nitrate and 0.1 g of polyvinylpyrrolidone were added to the calcium carbonate-ethanol mixture.

[0062] Example 3

[0063] The difference between this example and Example 2 is that

[0064] In step 4, the hydrothermal reaction conditions were hydrothermal reaction at 200 °C for 18 h.

[0065] Example 4

[0066] The difference between this example and Example 3 is that

[0067] In step 5, the gel was stirred at 70 °C for 2 h to ensure complete encapsulation, and then left to age for 2 h.

[0068] Example 5

[0069] The difference between this example and Example 4 is that

[0070] In step 5, it was dried at 80 °C for 6 h and calcined at 900 °C for 4 h to obtain the Cu-CaO@SiO2 core-shell catalyst.

[0071] Example 6

[0072] The difference between this example and Example 1 is that

[0073] In step 4, 0.4 mmol of copper nitrate and 0.01 g of polyvinylpyrrolidone were added to the calcium carbonate-ethanol mixture.

[0074] Example 7

[0075] The difference between this example and Example 6 is that

[0076] In step 4, the hydrothermal reaction conditions were hydrothermal reaction at 160 °C for 10 h.

[0077] Example 8

[0078] The difference between this example and Example 7 is that

[0079] In step five, the gel was stirred at 50 °C for 4 h to fully wrap it, and then left to age for 4 h.

[0080] Example 9

[0081] The difference between this example and Example 8 is that

[0082] In step five, it was dried at 60 °C for 6 h and calcined at 700 °C for 6 h to obtain the Cu-CaO@SiO2 core-shell catalyst.

[0083] Example 10

[0084] The difference between this example and Example 1 is that

[0085] The conditions for the hydrothermal reaction in step four were a hydrothermal reaction at 160 °C for 10 h.

[0086] Example 11

[0087] The difference between this example and Example 1 is that

[0088] The conditions for the hydrothermal reaction in step four were a hydrothermal reaction at 200 °C for 18 h.

[0089] Comparative Example 1

[0090] A preparation method of a CaO@SiO2 catalyst, comprising the following steps:

[0091] I. Extracting solid A: Using construction waste stone powder as a raw material, adding an excessive amount of hydrochloric acid with a concentration of 1.8 mol / L to 20 g of waste stone powder, dissolving soluble substances, taking the supernatant after full reaction and filtering to obtain solution B; the remaining precipitate was washed and dried thoroughly to obtain solid A;

[0092] II. Extracting solid C: Adding sodium carbonate to the solution B obtained in step one, precipitating after consuming the excess acidic solution, continuing to add sodium carbonate until the pH of the solution was 7 to obtain a precipitate, and the precipitate was washed and dried to obtain solid C, which was the extracted calcium carbonate;

[0093] III. Preparing solution D: Adding the solid A obtained in step one to sodium hydroxide solution, heating to dissolve the solid at 80 °C, and filtering to obtain solution D;

[0094] IV. Preparation of catalyst: Add 2 g of the extracted calcium carbonate (solid C) to solution D, add 0.1 g of polyvinylpyrrolidone, stir well and then add hydrochloric acid to form a gel. Stir the gel at 60 °C for 3 h to fully wrap it, then let it stand and age for 3 h. Wash it alternately with ethanol and deionized water 3 times, dry it at 70 °C for 6 h, and calcine it at 800 °C for 5 h to obtain the CaO@SiO2 catalyst.

[0095] Comparative Example 2

[0096] A preparation method of a CuO@SiO2 catalyst comprises the following steps:

[0097] I. Extract solid A: Use construction waste stone powder as raw material, add excessive hydrochloric acid with a concentration of 1.8 mol / L to 20 g of waste stone powder, dissolve soluble substances, filter after full reaction, and wash and dry the obtained precipitate thoroughly to obtain solid A;

[0098] II. Prepare solution D: Add the solid A obtained in step I to sodium hydroxide solution, heat it to dissolve the solid at 80 °C, and filter to obtain solution D;

[0099] III. Prepare the precursor: Add 1 mmol of copper nitrate and 0.05 g of polyvinylpyrrolidone to 100 mL of absolute ethanol, completely dissolve it, stir it in a water bath at 45 °C, add 1 mol / L ammonia water solution to adjust the pH value to 9 - 10, stir for 5 h and let it stand for 4 h. Carry out hydrothermal reaction at 180 °C for 12 h, wash the reaction product alternately with ethanol and deionized water 3 times, and dry it at 70 °C for 6 h to obtain the catalyst precursor;

[0100] IV. Prepare the catalyst: Add the prepared catalyst precursor to solution D, add 0.1 g of polyvinylpyrrolidone, stir well and then add hydrochloric acid to form a gel. Stir the gel at 60 °C for 3 h to fully wrap it, then let it stand and age for 3 h. Wash it alternately with ethanol and deionized water 3 times, dry it at 70 °C for 6 h, and calcine it at 800 °C for 5 h to obtain the CuO@SiO2 catalyst.

[0101] Example 12

[0102] I. Prepare 1 L of phenol solution with a concentration of 10 mg / L, place it in a glass reactor, introduce ozone for 2 min to keep the gas flow stable, control the ozone concentration at 2.96 mg / L, and the ozone ventilation flow rate at 1000 mL / min; then add 0.1 g of the Cu-CaO@SiO2 core-shell catalyst prepared in Example 1 for catalytic ozonation reaction;

[0103] II. The catalytic ozonation reaction time was 60 min. Sampling was carried out using a peristaltic pump, once every 10 min, with a sampling volume of 10 mL. After the sampled solution was filtered through a 0.22-μm filter membrane, the residual phenol concentration in the wastewater was detected using an ultraviolet-visible spectrophotometer (at a wavelength of 270 nm). The degradation curve of the phenol wastewater was plotted based on the detection data, and the removal rate was calculated;

[0104] Example 13

[0105] The difference between this example and Example 12 is that

[0106] in Step 1, the Cu-CaO@SiO2 core-shell catalyst prepared in Example 2 was used for the catalytic ozonation reaction.

[0107] Example 14

[0108] The difference between this example and Example 12 is that

[0109] in Step 1, the Cu-CaO@SiO2 core-shell catalyst prepared in Example 3 was used for the catalytic ozonation reaction.

[0110] Example 15

[0111] The difference between this example and Example 12 is that

[0112] in Step 1, the Cu-CaO@SiO2 core-shell catalyst prepared in Example 4 was used for the catalytic ozonation reaction.

[0113] Example 16

[0114] The difference between this example and Example 12 is that

[0115] in Step 1, the Cu-CaO@SiO2 core-shell catalyst prepared in Example 5 was used for the catalytic ozonation reaction.

[0116] Example 17

[0117] The difference between this example and Example 12 is that

[0118] in Step 1, the Cu-CaO@SiO2 core-shell catalyst prepared in Example 6 was used for the catalytic ozonation reaction.

[0119] Example 18

[0120] The difference between this example and Example 12 is that

[0121] in Step 1, the Cu-CaO@SiO2 core-shell catalyst prepared in Example 7 was used for the catalytic ozonation reaction.

[0122] Example 19

[0123] The difference between this example and Example 12 is that

[0124] in the first step, the Cu-CaO@SiO2 core-shell catalyst prepared in Example 8 is used for catalytic ozonation reaction.

[0125] Example 20

[0126] The difference between this example and Example 12 is that

[0127] in the first step, the Cu-CaO@SiO2 core-shell catalyst prepared in Example 9 is used for catalytic ozonation reaction.

[0128] Example 21

[0129] The difference between this example and Example 12 is that

[0130] in the first step, the Cu-CaO@SiO2 core-shell catalyst prepared in Example 10 is used for catalytic ozonation reaction.

[0131] Example 22

[0132] The difference between this example and Example 12 is that

[0133] in the first step, the Cu-CaO@SiO2 core-shell catalyst prepared in Example 11 is used for catalytic ozonation reaction.

[0134] Comparative Example 3

[0135] The difference between this comparative example and Example 12 is that

[0136] in the first step, the CaO@SiO2 catalyst prepared in Comparative Example 1 is used for catalytic ozonation reaction.

[0137] Comparative Example 4

[0138] The difference between this comparative example and Example 12 is that

[0139] in the first step, the CuO@SiO2 catalyst prepared in Comparative Example 2 is used for catalytic ozonation reaction.

[0140] Comparative Example 5

[0141] The difference between this comparative example and Example 12 is that

[0142] in the first step, no catalyst is used, and the phenol wastewater is treated by ozonation alone.

[0143] The Cu-CaO@SiO2 core-shell catalyst for extracting calcium silicate from waste stone powder obtained in Example 1, the CaO@SiO2 catalyst obtained in Comparative Example 1, and the CuO@SiO2 catalyst obtained in Comparative Example 2 were characterized by XRD. As Figure 4 shown, the Cu-CaO@SiO2 catalyst showed characteristic peaks of CuO and CaO, indicating that Cu and Ca had been successfully doped.

[0144] The Cu-CaO@SiO2 core-shell catalyst obtained in Example 1 was tested by scanning electron microscopy. As Figure 2 shown, the core-shell catalyst had a porous spherical core-shell structure.

[0145] The Cu-CaO@SiO2 core-shell catalyst obtained in Example 1 was tested by BET. As Figure 3 shown, the pore diameter of the core-shell catalyst was concentrated at 17.63 nm, and the catalyst had a mesoporous structure.

[0146] The Cu-CaO@SiO2 core-shell catalyst for extracting calcium silicate from waste stone powder obtained in Example 1 and the CuO@SiO2 catalyst obtained in Comparative Example 2 were characterized by Cu element XPS. As Figure 5 shown. It can be seen that the valence state of Cu element in each catalyst was Cu 2+ and reduced copper (Cu 0 / Cu + ). After adding Ca, the content of reduced copper (Cu 0 / Cu + ) increased.

[0147] As Figure 6 shown, the catalytic ozonation effects of Example 12 and Comparative Examples 3-5 were compared. It can be seen that after 60 min of treatment, the phenol removal rate reached 77.01%. In Comparative Example 3, the phenol removal rate after 60 min of catalytic ozonation treatment was 57.11%. In Comparative Example 4, the phenol removal rate after 60 min of catalytic ozonation treatment was 62.89%. In Comparative Example 5, the phenol removal rate after 60 min of single ozonation treatment was 27.38%. From Figure 6 it can be known that the catalytic ozonation efficiency of the Cu-CaO@SiO2 core-shell catalyst for extracting calcium silicate from waste stone powder prepared in the present invention was increased by 49.62% compared with the single ozone oxidation reaction, and was significantly higher than that of CaO@SiO2 and CuO@SiO 2。 As Figure 1 shown, the synergistic effect and electron transfer among multiple metals in the Cu-CaO@SiO2 core-shell catalyst of the present invention were beneficial to improving the catalytic performance. The results of the residual rate (%) of the phenol wastewater obtained by summarizing Examples 12-22 and Comparative Examples 3 to 5 are shown in Table 1.

[0148] Table 1

[0149]

[0150]

[0151] Although the present invention is disclosed as above, the scope of protection of the present invention is not limited thereto. Those skilled in the art of the present invention can make various changes and modifications without departing from the spirit and scope of the present disclosure, and these changes and modifications will all fall within the scope of protection of the present invention.

Claims

1. A preparation method of a Cu-CaO@SiO2 core-shell catalyst for extracting calcium silicate from waste stone powder, characterized in that, It includes the following steps: I. Extracting solid A: Using construction waste stone powder as raw material, adding an excessive amount of acidic solution to the waste stone powder for full reaction, filtering, and taking the supernatant to obtain solution B; washing and drying the precipitate to obtain solid A; II. Extracting solid C: Adding a precipitant to the solution B to consume the excess acidic solution to generate a precipitate, washing and drying the precipitate to obtain solid C; III. Preparing solution D: Adding the solid A to the alkaline solution M, heating until the solid dissolves, and filtering to obtain solution D; IV. Preparing the precursor: Adding the solid C obtained in step II to an organic solvent, performing ultrasonic dispersion, then adding an inorganic copper source and a surfactant, stirring, adding the alkaline solution M to adjust the pH value to alkaline, stirring and standing to obtain a mixed solution, subjecting the mixed solution to hydrothermal reaction, and washing and drying the reaction product to obtain the catalyst precursor; the molar ratio of the solid C to the inorganic copper source is 50:(5 - 1); V. Preparing the catalyst: Adding the catalyst precursor to the solution D, adding a crosslinking agent, fully stirring, adding an acidic solution to adjust the pH value to weakly acidic to generate a gel, and making the gel fully wrap and age through stirring, and obtaining the Cu - CaO@SiO2 core - shell catalyst through washing, drying, and calcination; The acidic solution in step I is one of hydrochloric acid, nitric acid, sulfuric acid, or oxalic acid solution; The alkaline solution M in step III is sodium hydroxide solution; The alkaline solution M in step IV is ammonia water.

2. The preparation method of the Cu-CaO@SiO2 core-shell catalyst for extracting calcium silicate from waste stone powder according to claim 1, characterized in that, The inorganic copper source in step IV is one of copper nitrate, copper acetate, copper chloride, or copper sulfate, and the surfactant is one of polyvinylpyrrolidone or cetyltrimethylammonium bromide.

3. The preparation method of the Cu-CaO@SiO2 core-shell catalyst for extracting calcium silicate from waste stone powder according to claim 1, characterized in that, The crosslinking agent in step V is polyvinylpyrrolidone.

4. The preparation method of the Cu-CaO@SiO2 core-shell catalyst for extracting calcium silicate from waste stone powder according to claim 1, characterized in that, The stirring time in step IV is not less than 5 h, and the standing time is not less than 4 h.

5. The preparation method of the Cu-CaO@SiO2 core-shell catalyst for extracting calcium silicate from waste stone powder according to claim 1, characterized in that, The conditions of the hydrothermal reaction in step IV are: the temperature is 160 - 200 °C, and the time is 10 h - 18 h.

6. The preparation method of the Cu-CaO@SiO2 core-shell catalyst for extracting calcium silicate from waste stone powder according to claim 1, characterized in that, The conditions for making the gel fully wrap and age through stirring in step V are: stirring at 50 - 70 °C for 2 - 4 h, and the aging time is 2 - 4 h.

7. The preparation method of the Cu-CaO@SiO2 core-shell catalyst for extracting calcium silicate from waste stone powder according to claim 1, characterized in that, The conditions of calcination in step V are: 700 - 900 °C, 4 - 6 h.

8. Use of a core-shell catalyst prepared by the method according to any one of claims 1 to 7 above, characterized in that, Using the Cu - CaO@SiO2 core - shell catalyst for extracting calcium and silicon from waste stone powder as a catalyst and combining it with ozone for treating phenol organic wastewater.

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