Cu-CaO-coated SiO2 core-shell catalyst for extracting silicon and calcium from waste stone powder as well as preparation method and application of Cu-CaO-coated SiO2 core-shell catalyst

Abstract

The invention discloses a core-shell catalyst for extracting silicon and calcium from waste stone powder as well as a preparation method and application of the core-shell catalyst, relates to the technical field of water treatment materials, and aims to solve the problems that a CuO core of an existing catalyst is unstable, metal ions are easy to leach and agglomerate, and CaO has no catalytic activity and is easy to corrode. According to the preparation method, silicon dioxide and calcium carbonate are extracted from building waste stone powder to serve as raw materials to prepare the Cu-CaO coated SiO2 core-shell catalyst, CuO is loaded on CaO through an impregnation method, and the catalyst is wrapped with a layer of SiO2 shell. The CuO provides active sites, the SiO2 is used as a protective shell, and the CaO is used as a cross-linking agent to enhance the interaction between the active metal and the protective shell. The catalyst is higher in catalytic activity, active sites are not prone to inactivation, the ion leaching rate is low, adsorption of ozone molecules and organic pollutants on the surface of the catalyst is facilitated, meanwhile, generation of active free radicals is promoted, and the catalytic performance is improved.

Description

Technical Field

[0001] The invention relates to the technical field of water treatment materials, and in particular to a core-shell catalyst for extracting silicon-calcium from waste stone powder, and a preparation method and 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. Waste stone powder is mainly divided into waste granite powder and waste marble powder. Waste granite powder is mainly composed of silicon dioxide (SiO2), and waste marble powder is mainly composed of calcium carbonate (CaCO3). The waste stone powder is randomly piled up, occupying arable land, easily generating dust, polluting the atmosphere, and easily causing alveolar dust accumulation after being inhaled by the human body, threatening human health. Because the stone powder particles are relatively fine, it is very easy to harden when exposed to water, affecting plant growth and causing serious damage to the ecological environment. At present, the recycling of waste stone powder is mainly used as cement, concrete components, building fillers, etc. These products are cheap and have low added value. 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 catalysts and ozone catalytic oxidation to degrade antibiotics provides a new idea for the resource utilization of waste stone powder.

[0003] Antibiotics cannot be completely absorbed after entering the body. The unabsorbed antibiotics are excreted from the body in the form of parent compounds and enter the water environment to pollute the water body, seriously threatening the health of the aquatic ecology. Therefore, it is necessary to remove these antibiotics. Catalytic ozonation technology has the characteristics of fast reaction speed, mild reaction conditions and high treatment efficiency. It has become the main method for removing difficult-to-degrade pollutants. The key to catalytic ozonation technology is the development of efficient catalysts. CuO itself has a unique spherical nanostructure and excellent mass transfer performance. It has the advantages of economy, low toxicity and good catalytic activity. It is widely used in catalytic ozonation processes. However, Cu 2+ It is easy to leach from the surface of CuO particles. Calcium-based catalysts contain strong alkaline sites, which form an alkaline environment in the reaction system and promote the generation of active free radicals. Calcium ions will not cause pollution in the reaction system, and it is a green and environmentally friendly material. However, CaO has no catalytic activity and is easy to corrode, and there are few studies on calcium-based catalysts in ozone catalytic oxidation technology. Summary of the invention

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

[0005] Existing catalysts have problems such as unstable CuO core, easy leaching and agglomeration of metal ions, and inactive and corrosive CaO.

[0006] The present invention adopts the following technical solutions to solve the above technical problems:

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

[0008] 1. Extracting solid A: Using construction waste stone powder as raw material, adding excess acid solution to the waste stone powder for full reaction, filtering, taking the supernatant to obtain solution B; taking the precipitate for washing and drying to obtain solid A;

[0009] 2. Extracting solid C: adding a precipitant to the solution B to consume excess acidic solution to generate a precipitate, washing and drying the precipitate to obtain solid C;

[0010] 3. Preparing solution D: adding the solid A into the alkaline solution M, heating until the solid is dissolved, and filtering to obtain solution D;

[0011] 4. Preparing a precursor: adding the solid C obtained in step 2 to an organic solvent, performing ultrasonic dispersion, adding an inorganic copper source and a surfactant, stirring, adding an 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] 5. Preparation of catalyst: Add the catalyst precursor to solution D, add the cross-linking agent, stir well, add the acidic solution to adjust the pH value to weak acidity, generate gel, and stir to fully wrap and age the gel, wash, dry and calcine to obtain the Cu-CaO@SiO2 core-shell catalyst.

[0013] Furthermore, in step 1, the acidic solution is one of hydrochloric acid, nitric acid, sulfuric acid or oxalic acid solution.

[0014] Furthermore, in step 4, the inorganic copper source is one of copper nitrate, copper acetate, copper chloride or copper sulfate, and the surfactant is one of polyvinyl pyrrolidone or hexadecyltrimethylammonium bromide.

[0015] Furthermore, in step five, the cross-linking agent is polyvinyl pyrrolidone.

[0016] Furthermore, in step 4, the stirring time is not less than 5 hours, and the standing time is not less than 4 hours.

[0017] Furthermore, the conditions of the hydrothermal reaction in step 4 are: temperature of 160-200° C., and time of 10 h to 18 h.

[0018] Furthermore, the stirring conditions of the gel in step 5 are: stirring at 50-70° C. for 2-4 hours, and the aging time is 2-4 hours.

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

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

[0021] The invention provides an application of a core-shell catalyst for extracting silicon-calcium from waste stone powder. The Cu-CaO@SiO2 core-shell catalyst for extracting silicon-calcium from waste stone powder is used as a catalyst in combination with ozone to treat phenol organic wastewater.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The present invention extracts silicon dioxide and calcium carbonate from construction waste stone powder as raw materials to prepare a Cu-CaO@SiO2 core-shell catalyst, loads CuO onto CaO by an impregnation method, and wraps a layer of SiO2 shell outside the catalyst, thereby 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-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, it 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 and improves the catalytic performance.

[0024] 2. The catalyst of the present invention has high mechanical strength, stable structure, good dispersibility, strong electron transfer ability, excellent effect of catalyzing ozone degradation of phenol wastewater, easy separation and recovery of the catalyst, no secondary pollution, and is suitable for deep treatment of antibiotic wastewater.

[0025] 3. The raw materials of the catalyst are widely available and inexpensive, and waste stone powder can be recycled. The preparation method of the catalyst is simple and safe to operate. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

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

[0030] Figure 5 The XPS spectra of the Cu element in the examples of the present invention, wherein Figure A represents the XPS spectra of the CuO@SiO2 catalyst obtained in Comparative Example 1, and Figure B represents the XPS spectra of the Cu element of the Cu-CaO@SiO2 core-shell catalyst obtained in Example 1;

[0031] Figure 6 It is the degradation curve of phenol wastewater in the embodiment of the present invention. DETAILED DESCRIPTION

[0032] In order to enable those skilled in the art to better understand the scheme of the present invention, exemplary implementations or embodiments of the present invention will be described below in conjunction with the accompanying drawings. Obviously, the described implementations or embodiments are only implementations or embodiments of a part of the present invention, not all of them. Based on the implementations or embodiments of the present invention, all other implementations or embodiments obtained by ordinary technicians in the field without creative work should fall within the scope of protection of the present invention.

[0033] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

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

[0035] 1. Extracting solid A: Using construction waste stone powder as raw material, adding excess acid solution to the waste stone powder for full reaction, filtering, taking the supernatant to obtain solution B; taking the precipitate for washing and drying to obtain solid A;

[0036] 2. Extracting solid C: adding a precipitant to the solution B to consume excess acidic solution to generate a precipitate, washing and drying the precipitate to obtain solid C;

[0037] 3. Preparing solution D: adding the solid A into the alkaline solution M, heating until the solid is dissolved, and filtering to obtain solution D;

[0038] 4. Preparing a precursor: adding the solid C obtained in step 2 to an organic solvent, performing ultrasonic dispersion, adding an inorganic copper source and a surfactant, stirring, adding an 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).

[0039] 5. Preparation of catalyst: Add the catalyst precursor to solution D, add the cross-linking agent, stir well, add the acidic solution to adjust the pH value to weak acidity, generate gel, and stir to fully wrap and age the gel, wash, dry and calcine to obtain the Cu-CaO@SiO2 core-shell catalyst.

[0040] In this embodiment, CuO is impregnated onto CaO to prepare a bimetallic catalyst, and a layer of SiO2 shell is wrapped around 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 1 is preferably one of hydrochloric acid, nitric acid, sulfuric acid or oxalic acid solution. Hydrochloric acid, nitric acid and sulfuric acid are all highly acidic. From a safety perspective, hydrochloric acid is preferred. Oxalic acid has good safety but relatively weak acidity.

[0042] In a typical embodiment of the present invention, the precipitant in step 2 is preferably one of sodium carbonate, potassium carbonate, sodium sulfate or potassium sulfate, and the precipitant 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 4 is preferably one of copper nitrate, copper acetate, copper chloride or copper sulfate, and the surfactant is preferably one of polyvinyl pyrrolidone or hexadecyltrimethylammonium bromide.

[0045] In a typical embodiment of the present invention, the crosslinking agent in step 5 is preferably polyvinyl pyrrolidone. Polyvinyl pyrrolidone is added to solution D as a crosslinking agent to promote the formation of SiO2 gel, so that it can better wrap around the catalyst surface as a shell to protect the catalyst.

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

[0047] In a typical embodiment of the present invention, the conditions for the hydrothermal reaction in step 4 are preferably: temperature of 160-200° C., and time of 10 h to 18 h.

[0048] In a typical embodiment of the present invention, the stirring conditions of the gel in step 5 are preferably: stirring at 50-70° C. for 2-4 hours, and the aging time is 2-4 hours.

[0049] In a typical embodiment of the present invention, the calcination conditions 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 also provided. The chemical formula of the core-shell catalyst is Cu-CaO@SiO2 and it is prepared by the above method.

[0051] In another typical embodiment of the present invention, there is also provided an application of a core-shell catalyst for extracting silicon-calcium from waste stone powder, wherein the Cu-CaO@SiO2 core-shell catalyst for extracting silicon-calcium from waste stone powder is used as a catalyst in combination with ozone to treat phenol organic wastewater.

[0052] Example 1

[0053] A method for extracting silicon-calcium Cu-CaO@SiO2 core-shell catalyst from waste stone powder comprises the following steps:

[0054] 1. Extracting solid A: Using construction waste stone powder as raw material, adding an excess of 1.8 mol / L hydrochloric acid to 20 g of waste stone powder to dissolve soluble substances, taking the supernatant after sufficient reaction and filtering to obtain solution B; the remaining precipitate is fully washed and dried to obtain solid A (the main component is silicon dioxide);

[0055] 2. Extracting solid C: adding sodium carbonate to solution B obtained in step 1, precipitate appears after consuming excess acid solution, continue to add sodium carbonate until the pH of the solution is 7, obtain precipitate, wash and dry the precipitate to obtain solid C (the main component is calcium carbonate);

[0056] 3. Prepare solution D: add the solid A obtained in step 1 into a sodium hydroxide solution, heat at 80°C until the solid is dissolved, and filter to obtain solution D;

[0057] 4. Preparation of precursor: Add 2g of extracted solid C to 100mL of anhydrous ethanol, and after 30min ultrasonic dispersion, add 1mmol of copper nitrate and 0.05g of polyvinyl pyrrolidone. After complete dissolution, stir in a water bath at 45°C, add 1mol / L ammonia solution to adjust the pH value to 9-10, stir for 5h, and let stand for 4h. Hydrothermally react at 180°C for 12h, wash the reaction product ethanol and deionized water alternately 3 times, and dry at 70°C for 6h to obtain a catalyst precursor;

[0058] 5. Preparation of catalyst: Add the prepared catalyst precursor to solution D, add 0.1 g of polyvinyl pyrrolidone, add hydrochloric acid after sufficient stirring 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 for 3 times, dry it at 70°C for 6 h, and calcine it at 800°C for 5 h to obtain a Cu-CaO@SiO2 core-shell catalyst.

[0059] Example 2

[0060] The difference between this embodiment and embodiment 1 is that:

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

[0062] Example 3

[0063] The difference between this embodiment and embodiment 2 is that:

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

[0065] Example 4

[0066] The difference between this embodiment and embodiment 3 is that:

[0067] In step five, the gel was stirred at 70° C. for 2 h to allow it to be fully coated, and then allowed to stand and age for 2 h.

[0068] Example 5

[0069] The difference between this embodiment and embodiment 4 is that:

[0070] In step five, the catalyst is dried at 80°C for 6 hours and calcined at 900°C for 4 hours to obtain a Cu-CaO@SiO2 core-shell catalyst.

[0071] Example 6

[0072] The difference between this embodiment and embodiment 1 is that:

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

[0074] Example 7

[0075] The difference between this embodiment and embodiment 6 is that:

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

[0077] Example 8

[0078] The difference between this embodiment and embodiment 7 is that:

[0079] In step five, the gel was stirred at 50° C. for 4 h to allow it to be fully coated, and then allowed to stand and age for 4 h.

[0080] Example 9

[0081] The difference between this embodiment and embodiment 8 is that:

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

[0083] Example 10

[0084] The difference between this embodiment and embodiment 1 is that:

[0085] The conditions for the hydrothermal reaction in step 4 are hydrothermal reaction at 160° C. for 10 h.

[0086] Embodiment 11

[0087] The difference between this embodiment and embodiment 1 is that:

[0088] The conditions for the hydrothermal reaction in step 4 are hydrothermal reaction at 200° C. for 18 h.

[0089] Comparative Example 1

[0090] A method for preparing a CaO@SiO2 catalyst comprises the following steps:

[0091] 1. Extracting solid A: Using construction waste stone powder as raw material, add an excess of 1.8 mol / L hydrochloric acid to 20 g of waste stone powder to dissolve the soluble substances. After sufficient reaction, take the supernatant and filter it to obtain solution B; after fully washing and drying the remaining precipitate, obtain solid A;

[0092] 2. Extracting solid C: adding sodium carbonate to solution B obtained in step 1, precipitate appears after consuming excess acid solution, continue to add sodium carbonate until the pH of the solution is 7, obtain precipitate, wash and dry the precipitate to obtain solid C, which is the extracted calcium carbonate;

[0093] 3. Prepare solution D: add the solid A obtained in step 1 into a sodium hydroxide solution, heat at 80°C until the solid is dissolved, and filter to obtain solution D;

[0094] 4. Preparation of catalyst: Add 2 g of extracted calcium carbonate (solid C) to solution D, add 0.1 g of polyvinyl pyrrolidone, stir thoroughly 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 for 3 times, dry it at 70°C for 6 h, and calcine it at 800°C for 5 h to obtain a CaO@SiO2 catalyst.

[0095] Comparative Example 2

[0096] A method for preparing a CuO@SiO2 catalyst comprises the following steps:

[0097] 1. Extracting solid A: Using construction waste stone powder as raw material, adding an excess of 1.8 mol / L hydrochloric acid to 20 g of waste stone powder to dissolve soluble substances, fully reacting and filtering, and then fully washing and drying the obtained precipitate to obtain solid A;

[0098] 2. Prepare solution D: add the solid A obtained in step 1 into a sodium hydroxide solution, heat at 80°C until the solid is dissolved, and filter to obtain solution D;

[0099] 3. Preparation of precursor: Add 1mmol copper nitrate and 0.05g polyvinyl pyrrolidone to 100mL anhydrous ethanol, stir in a water bath at 45°C after complete dissolution, add 1mol / L ammonia solution to adjust the pH value to 9-10, stir for 5h, and stand for 4h. Hydrothermally react at 180°C for 12h, wash the reaction product ethanol and deionized water alternately 3 times, and dry at 70°C for 6h to obtain a catalyst precursor;

[0100] 4. Preparation of catalyst: Add the prepared catalyst precursor to solution D, add 0.1 g of polyvinyl pyrrolidone, stir thoroughly and then add hydrochloric acid to form a gel. Stir the gel at 60°C for 3 hours to fully wrap it, then let it stand and age for 3 hours, wash it alternately with ethanol and deionized water for 3 times, dry it at 70°C for 6 hours, and calcine it at 800°C for 5 hours to obtain a CuO@SiO2 catalyst.

[0101] Example 12

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

[0103] 2. The catalytic ozonation reaction time is 60 minutes. A peristaltic pump is used for sampling. The sampling is performed every 10 minutes with a sampling volume of 10 mL. After the sampling solution is filtered through a 0.22 μm filter membrane, a UV-visible spectrophotometer (at a wavelength of 270 nm) is used to detect the residual phenol concentration in the wastewater. The degradation curve of phenol wastewater is drawn based on the test data, and the removal rate is calculated.

[0104] Embodiment 13

[0105] The difference between this embodiment and embodiment 12 is that:

[0106] In step 1, the Cu-CaO@SiO2 core-shell catalyst prepared in Example 2 is used to carry out catalytic ozonation reaction.

[0107] Embodiment 14

[0108] The difference between this embodiment and embodiment 12 is that:

[0109] In step 1, the Cu-CaO@SiO2 core-shell catalyst prepared in Example 3 is used to carry out catalytic ozonation reaction.

[0110] Embodiment 15

[0111] The difference between this embodiment and embodiment 12 is that:

[0112] In step 1, the Cu-CaO@SiO2 core-shell catalyst prepared in Example 4 is used to carry out catalytic ozonation reaction.

[0113] Example 16

[0114] The difference between this embodiment and embodiment 12 is that:

[0115] In step 1, the Cu-CaO@SiO2 core-shell catalyst prepared in Example 5 is used to carry out catalytic ozonation reaction.

[0116] Embodiment 17

[0117] The difference between this embodiment and embodiment 12 is that:

[0118] In step 1, the Cu-CaO@SiO2 core-shell catalyst prepared in Example 6 is used to carry out catalytic ozonation reaction.

[0119] Embodiment 18

[0120] The difference between this embodiment and embodiment 12 is that:

[0121] In step 1, the Cu-CaO@SiO2 core-shell catalyst prepared in Example 7 is used to carry out catalytic ozonation reaction.

[0122] Embodiment 19

[0123] The difference between this embodiment and embodiment 12 is that:

[0124] In step 1, the Cu-CaO@SiO2 core-shell catalyst prepared in Example 8 is used to carry out catalytic ozonation reaction.

[0125] Embodiment 20

[0126] The difference between this embodiment and embodiment 12 is that:

[0127] In step 1, the Cu-CaO@SiO2 core-shell catalyst prepared in Example 9 is used to carry out catalytic ozonation reaction.

[0128] Embodiment 21

[0129] The difference between this embodiment and embodiment 12 is that:

[0130] In step 1, the Cu-CaO@SiO2 core-shell catalyst prepared in Example 10 is used to carry out catalytic ozonation reaction.

[0131] Embodiment 22

[0132] The difference between this embodiment and embodiment 12 is that:

[0133] In step 1, the Cu-CaO@SiO2 core-shell catalyst prepared in Example 11 is used to carry out catalytic ozonation reaction.

[0134] Comparative Example 3

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

[0136] In step 1, the CaO@SiO2 catalyst prepared in Comparative Example 1 is used to carry out catalytic ozonation reaction.

[0137] Comparative Example 4

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

[0139] In step 1, the CuO@SiO2 catalyst prepared in Comparative Example 2 is used to carry out catalytic ozonation reaction.

[0140] Comparative Example 5

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

[0142] In step 1, no catalyst is used, and ozonation treatment of phenol wastewater is performed alone.

[0143] The Cu-CaO@SiO2 core-shell catalyst for extracting silicon-calcium 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. Figure 4 As shown, the Cu-CaO@SiO2 catalyst exhibits characteristic peaks of CuO and CaO, indicating that Cu and Ca have been successfully doped.

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

[0145] The Cu-CaO@SiO2 core-shell catalyst obtained in Example 1 was subjected to BET test. Figure 3 As shown, the pore size of the core-shell catalyst is concentrated at 17.63 nm, and the catalyst has a mesoporous structure.

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

[0147] like Figure 6 As shown, the catalytic ozonation effects of Example 12 and Comparative Examples 3-5 are compared. It can be seen that the phenol removal rate reaches 77.01% after 60 minutes of treatment, the phenol removal rate after 60 minutes of catalytic ozonation treatment in Comparative Example 3 is 57.11%, the phenol removal rate after 60 minutes of catalytic ozonation treatment in Comparative Example 4 is 62.89%, and the phenol removal rate after 60 minutes of single ozonation treatment in Comparative Example 5 is 27.38%. Figure 6 It can be seen that the catalytic ozonation efficiency of the Cu-CaO@SiO2 core-shell catalyst prepared by the present invention for extracting silicon and calcium from waste stone powder is 49.62% higher than that of the single ozone oxidation reaction, and is significantly higher than that of CaO@SiO2 and CuO@SiO 2。 like Figure 1 As shown, the synergistic effect and electron transfer between multiple metals in the Cu-CaO@SiO2 core-shell catalyst of the present invention are conducive to improving the catalytic performance. The residual rate (%) of phenol wastewater obtained in Examples 12-22 and Comparative Examples 3 to 5 is summarized in Table 1.

[0148] Table 1

[0149]

[0150]

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

Claims

1. A method for preparing a Cu-CaO@SiO2 core-shell catalyst for extracting silicon and calcium from waste stone powder, characterized in that: The steps include:

1. Extracting solid A: Using construction waste stone powder as raw material, adding excess acid solution to the waste stone powder for full reaction, filtering, taking the supernatant to obtain solution B; taking the precipitate for washing and drying to obtain solid A; 2. Extracting solid C: adding a precipitant to the solution B to consume excess acidic solution to generate a precipitate, washing and drying the precipitate to obtain solid C; 3. Preparing solution D: adding the solid A into the alkaline solution M, heating until the solid is dissolved, and filtering to obtain solution D; 4. Preparing a precursor: adding the solid C obtained in step 2 to an organic solvent, performing ultrasonic dispersion, adding an inorganic copper source and a surfactant, stirring, adding an 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).

5. Preparation of catalyst: Add the catalyst precursor to solution D, add the cross-linking agent, stir well, add the acidic solution to adjust the pH value to weak acidity, generate gel, and stir to fully wrap and age the gel, wash, dry and calcine to obtain the Cu-CaO@SiO2 core-shell catalyst.

2. The method for preparing a Cu-CaO@SiO2 core-shell catalyst for extracting silicon and calcium from waste stone powder according to claim 1, characterized in that: Step 1: The acidic solution is one of hydrochloric acid, nitric acid, sulfuric acid or oxalic acid solution.

3. The method for preparing a Cu-CaO@SiO2 core-shell catalyst for extracting silicon and calcium from waste stone powder according to claim 1, characterized in that: In step 4, the inorganic copper source is one of copper nitrate, copper acetate, copper chloride or copper sulfate, and the surfactant is one of polyvinyl pyrrolidone or hexadecyltrimethylammonium bromide.

4. The method for preparing a Cu-CaO@SiO2 core-shell catalyst for extracting silicon and calcium from waste stone powder according to claim 1, characterized in that: In step 5, the cross-linking agent is polyvinyl pyrrolidone.

5. The method for preparing a Cu-CaO@SiO2 core-shell catalyst for extracting silicon and calcium from waste stone powder according to claim 1, characterized in that: The stirring time in step 4 is not less than 5 hours, and the standing time is not less than 4 hours.

6. The method for preparing a Cu-CaO@SiO2 core-shell catalyst for extracting silicon and calcium from waste stone powder according to claim 1, characterized in that: The conditions of the hydrothermal reaction in step 4 are: temperature of 160-200° C. and time of 10 h to 18 h.

7. The method for preparing a Cu-CaO@SiO2 core-shell catalyst for extracting silicon and calcium from waste stone powder according to claim 1, characterized in that: The stirring conditions of the gel in step 5 are: stirring at 50-70° C. for 2-4 hours, and the aging time is 2-4 hours.

8. The method for preparing a Cu-CaO@SiO2 core-shell catalyst for extracting silicon and calcium from waste stone powder according to claim 1, characterized in that: The calcination conditions in step 5 are: 700-900°C, 4-6h.

9. A core-shell catalyst, characterized in that: The chemical formula of the core-shell catalyst is Cu-CaO@SiO2, and it is prepared by the method described in claim 1.

10. An application of a core-shell catalyst for extracting silicon-calcium from waste stone powder, characterized in that: The Cu-CaO@SiO2 core-shell catalyst, which is prepared by extracting silicon and calcium from waste stone powder, was used in combination with ozone to treat phenol organic wastewater.

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