Silver modified calcium carbonate with piezoelectric activity and preparation method and application thereof

Abstract

The invention belongs to the field of piezoelectric material preparation, and particularly relates to silver modified calcium carbonate with piezoelectric activity and a preparation method and application thereof. The invention provides silver modified calcium carbonate with piezoelectric activity. The silver modified calcium carbonate is in a cubic embedded shape with a rough surface. Calcite crystal form calcium carbonate is used as a substrate, and silver nanoparticles are loaded on the surface; the prepared silver modified calcium carbonate has good piezoelectric catalysis performance. The catalyst can be applied to degradation of pollutants; when rhodamine B is degraded, the rate constant can reach 0.14571 min <-1 >; the stability and the reusability are good, and the application range is wide. The preparation method of the material is based on a precipitation method and a piezoelectric electrochemical process; the method has the advantages of environment friendliness, simplicity in operation, low cost and easiness in mass production. The preparation method is simple, environment-friendly and low in energy consumption, and batch preparation can be realized; the prepared silver modified calcium carbonate has good piezoelectric catalysis performance and can be applied to degradation of pollutants; the prepared silver modified calcium carbonate has good stability and reusability.

Description

Technical Field

[0001] The invention belongs to the field of piezoelectric material preparation, and in particular relates to silver-modified calcium carbonate with piezoelectric activity, a preparation method and application thereof. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention, and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] The piezoelectric catalytic process can convert mechanical energy into electrical energy and chemical energy, and has important applications in water decomposition, hydrogen evolution, hydrogen peroxide production, and environmental remediation. At present, piezoelectric materials are limited by heavy metal precipitation or time-consuming and energy-consuming preparation processes, so it is difficult to mass-produce them to meet the needs of practical applications. Therefore, it is necessary to find a piezoelectric material with good piezoelectric catalytic performance and a simple, safe, and economical preparation process.

[0004] Calcium carbonate is a resource-rich and environmentally friendly material that exists in nature in the form of anhydrous crystalline phases (such as vaterite, calcite and aragonite), hydrated crystalline phases (calcium carbonate hexahydrate and calcium carbonate monohydrate) or amorphous calcium carbonate. Due to the diversity of calcium carbonate crystal forms and morphologies, it has a variety of uses and has been widely used in industries such as papermaking, plastics, rubber and food fillers, and drug carriers; however, calcium carbonate (CaCO3) itself does not have piezoelectricity, and related research is not comprehensive. Summary of the invention

[0005] In order to solve the defects of the prior art, the present invention proposes a silver-modified calcium carbonate with piezoelectric activity and a preparation method thereof, and applies the same to the degradation of pollutants.

[0006] The scheme adopted is summarized as follows: Under magnetic stirring, a certain amount of Ca 2+ Alcohol-water solution dripped into CO3 2- In an alcohol-water solution, adjust the pH to a weak base and continue stirring for a certain period of time. Stop stirring and age the mother liquor. The resulting precipitate is washed and dried. Add Ag + Ultrasonic vibration is applied to the methanol-water solution for a certain period of time, and the obtained precipitate is washed and dried, thereby successfully preparing silver-modified calcium carbonate with piezoelectric activity.

[0007] The first aspect of the present invention provides a silver-modified calcium carbonate with piezoelectric activity, wherein the silver-modified calcium carbonate is in a cubic mosaic shape with a rough surface; calcite crystalline calcium carbonate is used as a substrate, and silver nanoparticles are loaded on the surface.

[0008] In some embodiments of the present invention, the size of the silver-modified calcium carbonate is 2 μm-4 μm;

[0009] In some embodiments of the present invention, the silver content in the silver-modified calcium carbonate is 1.9%-12.7% by mass of the calcium carbonate.

[0010] The second aspect of the present invention provides a method for preparing the silver-modified calcium carbonate having piezoelectric activity, comprising the following steps:

[0011] S1. Stir the Ca 2+ The alcohol solution is dropped into CO3 2- In alcohol aqueous solution;

[0012] S2. Adjust the pH to a weak base, continue stirring for a period of time, stop stirring, and age;

[0013] S3. Separating the precipitate from the system of step S2, washing and drying;

[0014] S4. Add Ag to the precipitate obtained in step S3. + Ultrasonic treatment in alcohol-water solution system;

[0015] S5. Wash the precipitate, and dry it to obtain silver-modified calcium carbonate.

[0016] In some embodiments of the present invention, in step S1, Ca 2+ The source is selected from any one or a combination of Ca(NO3)2, CaCl2, CaSO4, CaO, and CaCO3;

[0017] In some embodiments of the present invention, in step S1, CO3 2- The source is selected from one or a combination of Na2CO3 or K2CO3.

[0018] In some embodiments of the present invention, in step S1, Ca 2+ With CO3 2- The molar ratio is 1:1-2:1; in a preferred embodiment, the concentration ratio is preferably 1.2:1.

[0019] In some embodiments of the present invention, in step S1, Ca 2+ The solution dripping rate is 0.01mL / s~2mL / s.

[0020] In some preferred embodiments, in step S1, the alcohol aqueous solution is ethanol-water, ethanol:water=1:2.

[0021] In some preferred embodiments, the stirring method is magnetic stirring.

[0022] In some embodiments of the present invention, in step S2, the pH is 10-11; the stirring time is 1-5 h; and the stirring rate is preferably 1000-3500 rpm.

[0023] In some embodiments, in step S2, the aging time is 1-24 hours.

[0024] In some embodiments of the present invention, in step S4, the alcohol-water solution system is a methanol-water system;

[0025] In some embodiments of the present invention, in step S4, Ag + The source is selected from one or a combination of CH3COOAg and AgNO3;

[0026] In some embodiments of the present invention, in step S4, AgNO3 is dissolved in a methanol-water solution with a concentration of 0.042 g / L to 0.26 g / L, preferably 0.064 g / L.

[0027] In some embodiments of the present invention, in step S4, the dispersion method is ultrasonic treatment, and the treatment time is 20-60 min.

[0028] The third aspect of the present invention provides the use of the silver-modified calcium carbonate, or the silver-modified calcium carbonate prepared by the preparation method, in degrading organic pollutants.

[0029] In some embodiments of the present invention, the organic pollutants include, but are not limited to, one or a combination of rhodamine B, methylene blue, crystal violet, and methyl orange;

[0030] In some embodiments of the present invention, the concentration of the pollutant ranges from 5 mg / L to 25 mg / L.

[0031] Furthermore, the method for degrading pollutants is as follows: adding the silver-modified calcium carbonate to a pollutant solution for reaction under ultrasonic vibration.

[0032] Compared with the prior art, the beneficial effects of the present invention are at least:

[0033] The present invention uses a precipitation method and a piezoelectric chemical process to prepare silver-modified calcium carbonate with piezoelectric activity, and its characteristics and advantages are described as follows:

[0034] (1) The silver-modified calcium carbonate with piezoelectric activity provided by the present invention is in the shape of a cubic mosaic with a rough surface; calcite crystalline calcium carbonate is used as a substrate, and silver nanoparticles are loaded on the surface; and it has good piezoelectric catalytic performance;

[0035] (2) When the material is used for the degradation of organic pollutants, it has good stability and reusability and a wide range of applications; the rate constant for the degradation of rhodamine B can reach 0.14571 min -1 ; After being reused 8 times, it still maintains high catalytic activity;

[0036] (3) The preparation method of this material is based on precipitation method and piezoelectric chemical process; the preparation method is simple, environmentally friendly, easy to operate, low-cost, and easy to mass produce. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The accompanying drawings are used to provide a further understanding of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the present application and do not constitute a limitation of the present application. In the accompanying drawings:

[0038] Figure 1 is the X-ray diffraction spectrum (XRD) of silver-modified calcium carbonate;

[0039] Figure 2 is the X-ray photoelectron spectroscopy (XPS) diagram of silver-modified calcium carbonate;

[0040] Figure 3 is a scanning electron microscope (SEM) image of silver-modified calcium carbonate;

[0041] Figure 4 is the energy dispersive X-ray spectrum (EDS) diagram of silver-modified calcium carbonate;

[0042] Figure 5 Figure 2 shows the piezoelectric catalytic degradation of pollutants by silver-modified calcium carbonate;

[0043] Figure 6 This is a diagram showing the effect of piezoelectric catalytic degradation of different pollutants by silver-modified calcium carbonate;

[0044] Figure 7 This is a cycle test diagram of the piezoelectric catalytic degradation of Rhodamine B by silver-modified calcium carbonate. DETAILED DESCRIPTION

[0045] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the embodiments of the specification.

[0046] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0047] Example 1: Preparation of silver-modified calcium carbonate

[0048] 0.12mol / L Ca(NO3)2 solution (the solution is ethanol-water, ethanol: water = 1:2) was uniformly added dropwise at a rate of 1mL / s to 0.1mol / L Na2CO3 solution (the solution is ethanol-water, ethanol: water = 1:2). After adjusting the pH to 10-11 with NaOH solution, the mixture was stirred continuously for 5h at a stirring rate of 3500rpm, and the precipitate was aged in the mother liquor for 24h, and then the precipitate obtained by centrifugation was washed with ultrapure water and ethanol respectively, and then dried at room temperature to obtain calcium carbonate. Then 1.05mg, 1.6mg, 3.25mg, and 6.5mg of AgNO3 were added and dissolved in 23ml of water, and 2ml of methanol was added to form a uniform solution. 35 mg of calcium carbonate was added to a silver nitrate solution and ultrasonically vibrated for 30 minutes. The resulting precipitate was washed and dried to obtain silver-modified calcium carbonate; they were recorded as 0.03Ag-CaCO3, 0.05Ag-CaCO3, 0.1Ag-CaCO3, and 0.2Ag-CaCO3, respectively.

[0049] Example 2: Preparation of silver-modified calcium carbonate

[0050] 0.12mol / L CaCl2 solution (the solution is ethanol-water, ethanol: water = 1:2) is uniformly added dropwise at a rate of 1mL / s to 0.1mol / L K2CO3 solution (the solution is ethanol-water, ethanol: water = 1:2). After adjusting the pH to 10-11 with NaOH solution, the mixture is continuously stirred for 5h at a stirring rate of 3500rpm, and the precipitate is aged in the mother liquor for 24h, and then the precipitate obtained by centrifugation is washed with ultrapure water and ethanol respectively, and then dried at room temperature to obtain calcium carbonate. Then 1.6mg of AgNO3 is dissolved in 23ml of water, and 2ml of methanol is added to form a uniform solution. 35mg of calcium carbonate is added to the silver nitrate solution and ultrasonically vibrated for 30min. The resulting precipitate is washed and dried to obtain silver-modified calcium carbonate.

[0051] Example 3: Preparation of silver-modified calcium carbonate

[0052] 0.12mol / L CaSO4 solution (the solution is ethanol-water, ethanol: water = 1:2) is uniformly added dropwise at a rate of 1mL / s to 0.1mol / L Na2CO3 solution (the solution is ethanol-water, ethanol: water = 1:2). After adjusting the pH to 10-11 with NaOH solution, the mixture is continuously stirred for 5h at a stirring rate of 3500rpm, and the precipitate is aged in the mother liquor for 24h, and then the precipitate obtained by centrifugation is washed with ultrapure water and ethanol respectively, and then dried at room temperature to obtain calcium carbonate. Then 1.6mg of AgNO3 is dissolved in 23ml of water, and 2ml of methanol is added to form a uniform solution. 35mg of calcium carbonate is added to the silver nitrate solution and ultrasonically vibrated for 30min. The resulting precipitate is washed and dried to obtain silver-modified calcium carbonate.

[0053] Characterization of Silver Modified Calcium Carbonate:

[0054] The CaCO3 and silver-modified calcium carbonate prepared in Example 1 were characterized.

[0055] like Figure 1 As shown, the diffraction peaks centered at 23.1°, 29.4°, 36.0°, 39.4°, 43.1°, 47.5°, and 48.5° indicate that the calcium carbonate is calcite crystals. Except for the calcium carbonate substrate, all silver-loaded samples have a diffraction peak at 38.3°, which is a characteristic peak of silver nanoparticles.

[0056] The state of the elements was analyzed by X-ray photoelectron spectroscopy (XPS) (0.05Ag-CaCO3 prepared in Example 1), as shown in FIG. Figure 2 As shown; the binding energy is around 368eV and 374eV, and the spin-orbit splitting is 6eV, which confirms that the chemical state of the silver element is metallic silver.

[0057] like Figure 3 As shown in the figure, the calcium carbonate sample is in the shape of a cube with a rough surface, and silver nanoparticles are loaded on its surface; + As the concentration increases, the loading amount gradually increases, and different amounts of silver are deposited on the surface of calcium carbonate.

[0058] like Figure 4 As shown, from the energy spectrum (EDS) element distribution diagram, it can be seen that calcium (Ca), carbon (C), oxygen (O) and silver (Ag) are evenly distributed and match each other well.

[0059] Application Example 1: Experiment on degradation of organic dyes by piezoelectric catalysis of silver-modified calcium carbonate

[0060] The piezoelectric catalytic performance of Ag-modified CaCO3 was evaluated by its degradation of Rhodamine B under ultrasonic vibration.

[0061] The specific experimental method is to disperse 35mg of the silver-modified calcium carbonate obtained in Example 1 in 10mg / L rhodamine B solution (25mL), transfer the mixed solution to an ultrasonic cleaning machine (40kHz, 210W) for piezoelectric catalytic reaction, and stir in the dark for 30min before the piezoelectric catalytic reaction to reach absorption-analysis balance between the dye and the catalyst sample. The experiment is carried out in a dark environment to exclude the interference of photocatalysis. In order to detect the decolorization of rhodamine B, 2mL of mixed solution is taken every 5min, and supernatant is obtained by centrifugation. The light absorption of the obtained dye solution is measured using an ultraviolet-visible spectrophotometer (UV-3600plus, JPN).

[0062] like Figure 5 As shown, the degradation efficiency of rhodamine B by silver-loaded calcium carbonate in Example 1 is significantly improved compared with that of calcium carbonate; it is basically completely degraded within 25 minutes. The absorbance of rhodamine B added with 0.05Ag-CaCO3 and 0.1Ag-CaCO3 samples is basically 0 at 20 minutes; the degradation rate of the sample added with 0.05Ag-CaCO3 reaches 99.99%, and the rate constant k is 0.14571min -1 , which shows that the prepared silver-modified calcium carbonate has good piezoelectric catalytic performance in degrading pollutants.

[0063] Application Example 2: Piezoelectric Catalytic Performance of Silver-Modified Calcium Carbonate

[0064] The specific experimental method is to disperse silver-modified calcium carbonate (0.05Ag-CaCO3) in (25mL) 10mg / L rhodamine B, methylene blue, crystal violet, and methyl orange solutions, and then transfer the mixed solution to an ultrasonic cleaner (40kHz, 210W) for piezoelectric catalytic reaction. Stir for 30min in the dark to achieve absorption-analysis equilibrium between the dye and the catalyst sample. The experiment was carried out in a dark environment to eliminate the interference of photocatalysis. In order to detect the decolorization of each pollutant, 2mL of the mixed solution was taken every 5min and centrifuged to obtain the supernatant. The light absorption of the obtained dye solution was measured using an ultraviolet-visible spectrophotometer (UV-3600plus, JPN).

[0065] like Figure 6 As shown, the silver-modified calcium carbonate prepared by the present invention can completely degrade rhodamine B, methylene blue, crystal violet and methyl orange within 30 minutes, wherein rhodamine B and methylene blue can be completely degraded within 20 minutes.

[0066] Application Example 3: Repeatability and Stability Test

[0067] The repeatability and stability of the piezoelectric catalysis of silver-modified calcium carbonate (0.05Ag-CaCO3) were evaluated by its degradation of rhodamine B under the same conditions. The silver-modified calcium carbonate was centrifuged, washed, dried and reused for the degradation of rhodamine B.

[0068] like Figure 7 As shown, the degradation rate of rhodamine B did not decrease significantly after 8 repetitions, indicating that the silver-modified calcium carbonate prepared by this method has stable performance and is reusable.

[0069] In summary, the present invention provides a silver-modified calcium carbonate with piezoelectric activity, which is in a cubic mosaic with a rough surface; calcite crystalline calcium carbonate is used as a substrate, and silver nanoparticles are loaded on the surface; the prepared silver-modified calcium carbonate has good piezoelectric catalytic performance and can be used for the degradation of pollutants; when degrading rhodamine B, the rate constant can reach 0.14571min -1 It has good stability and reusability and a wide range of applications. The preparation method of this material is based on precipitation and piezoelectric chemical processes; it has the advantages of being environmentally friendly, simple to operate, low-cost, and easy to mass produce.

[0070] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the present invention.

Claims

1. A silver-modified calcium carbonate having piezoelectric activity, characterized in that: The silver-modified calcium carbonate is in a cubic mosaic shape with a rough surface; calcite crystal calcium carbonate is used as a substrate, and silver nanoparticles are loaded on the surface.

2. The piezoelectrically active silver-modified calcium carbonate according to claim 1, characterized in that: The silver content in the silver-modified calcium carbonate is 1.9%-12.7% of the mass of the calcium carbonate.

3. The method for preparing the piezoelectrically active silver-modified calcium carbonate according to claim 1 or 2, characterized in that: The steps include: S1. Stir the Ca 2+ The alcohol solution is dropped into CO3 2- In alcohol aqueous solution; S2. Adjust the pH to a weak base, continue stirring for a period of time, stop stirring, and age; S3. Separating the precipitate from the system of step S2, washing and drying; S4. Add Ag to the precipitate obtained in step S3. + Ultrasonic treatment in alcohol-water solution system; S5. Wash the precipitate, and dry it to obtain silver-modified calcium carbonate.

4. The method for preparing silver-modified calcium carbonate having piezoelectric activity according to claim 3, characterized in that: In step S1, Ca 2+ The source is selected from any one or a combination of Ca(NO3)2, CaCl2, CaSO4, CaO, and CaCO3; And / or, in step S1, CO3 2- The source is selected from one or a combination of Na2CO3 or K2CO3.

5. The method for preparing silver-modified calcium carbonate having piezoelectric activity according to claim 3, characterized in that: In step S1, Ca 2+ With CO3 2- The molar ratio is 1:1-2:1; And / or, in step S1, Ca 2+ The solution dripping rate is 0.01mL / s~2mL / s.

6. The method for preparing silver-modified calcium carbonate having piezoelectric activity according to claim 3, characterized in that: In step S2, the pH is 10-11; the stirring time is 1-5h; And / or, in step S2, the aging time is 1-24h.

7. The method for preparing silver-modified calcium carbonate having piezoelectric activity according to claim 3, characterized in that: In step S4, Ag + The source is selected from one or a combination of CH3COOAg and AgNO3; and / or, in step S4, AgNO3 is dissolved in a methanol-water solution at a concentration of 0.042 g / L to 0.26 g / L; And / or, in step S4, the ultrasonic treatment time is 20-60 min.

8. Use of the silver-modified calcium carbonate according to claim 1 or 2 in degrading organic pollutants, Or the use of silver-modified calcium carbonate prepared by the preparation method according to any one of claims 3 to 7 in degrading organic pollutants.

9. The use of the silver-modified calcium carbonate in degrading organic pollutants according to claim 8, characterized in that: The organic pollutants include but are not limited to rhodamine B, methylene blue, crystal violet, and methyl orange; And / or, the concentration of the pollutant ranges from 5 mg / L to 25 mg / L.

10. The use of silver-modified calcium carbonate in degrading organic pollutants according to claim 9, characterized in that: Method for degrading pollutants: adding the silver-modified calcium carbonate into a pollutant solution to react under ultrasonic vibration.

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