Cerium dioxide-silica composite material, method for preparing the same, and use thereof

Abstract

The present application relates to ceria-silica composite material and its preparation method and application, including (1) mixing choline chloride and cerium salt, heating reaction to obtain a mixture; (2) adding tetraethyl orthosilicate to the mixture of step (1), stirring after reaction, drying and calcining to obtain ceria-silica composite material. The composite material provided by the present application is used for adsorbing rhodamine B, and has the advantages of rapid adsorption, high adsorption capacity, low attenuation rate of cyclic use and the like.

Description

Technical Field

[0001] This invention relates to cerium dioxide-silica composite materials, their preparation methods, and applications, specifically to a cerium dioxide-silica composite material, its preparation method, and its application in treating wastewater containing rhodamine B. Background Technology

[0002] Adsorption methods are widely used due to their simple processes and operation, and the fact that they do not introduce new pollutants. The core of adsorption lies in developing efficient and durable adsorption materials. Silica has various porous structures and is widely used as an adsorbent; however, adsorbents have limited adsorption capacity and require regeneration or replacement after saturation. If the adsorbent is catalytically degraded after saturation, adsorbent regeneration can be achieved, extending its service life. The rare earth element cerium has a unique outer electronic structure, which can effectively store and release electrons, allowing cerium ions to exhibit +3 and +4 valence states. Therefore, CeO2 materials contain a large number of oxygen holes, exhibiting superior oxygen storage and release capabilities. The interconversion between Ce(III) and Ce(IV) also gives CeO2 materials unique redox catalytic capabilities. However, nano-CeO2 particles have drawbacks such as easy aggregation and poor dispersibility.

[0003] CN106987229A discloses a core-shell coated composite particle with mesoporous silica microspheres as the core and cerium oxide nanoparticles as the shell, its preparation method, and its application in chemical mechanical polishing. This invention uses mesoporous silica microspheres with radially arranged mesoporous channels as the core, cerium nitrate hexahydrate as the cerium source, and hexamethylenetetramine, ammonia, or sodium hydroxide as the precipitant, synthesized in a liquid phase system. By optimizing the conditions, the coating state and distribution of cerium oxide nanoparticles on the surface of the mesoporous silica microspheres are adjusted, thereby synthesizing uniformly distributed, complete monodisperse spherical mesoporous silica / cerium oxide composite particles with cerium oxide nanoparticles uniformly coated on the surface of the mesoporous silica microsphere core. This composite particle is suitable for reducing the roughness of polished surfaces and avoiding mechanical damage such as scratches on the polished surface.

[0004] CN 114561719 A discloses a cerium oxide / silica composite fiber material with a fiber interwoven structure, its preparation method, and its application. The material is prepared through the following process: (1) a cerium source is dispersed in solvent A, and then polymer template A is added to obtain a cerium precursor solution; (2) a silicon source and catalyst are dispersed in solvent B, reacted to obtain a silica sol, and then polymer template B is added to obtain a silicon precursor solution; (3) the cerium precursor solution and the silicon precursor solution are respectively loaded into independent syringes and electrospun on the same receiving roller to obtain a cerium oxide / silica composite fiber precursor; (4) the obtained cerium oxide / silica composite fiber precursor is calcined to obtain the target product. Compared with the prior art, this composite fiber material is in the form of a thin film, the preparation process is relatively complex, and the removal effect of pollutants is not explained.

[0005] Rhodamine B is a widely used organic synthetic dye with toxicity, carcinogenicity, and teratogenicity. Dyeing wastewater containing Rhodamine B has high color intensity, is difficult to biodegrade, and harms the ecological environment and human health. Currently available composite materials for Rhodamine B removal suffer from low adsorption capacity and poor regeneration performance. Therefore, researching and developing highly efficient adsorbents with good recyclability for Rhodamine B removal is crucial for solving the problem of Rhodamine B pollution in water bodies. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a cerium dioxide-silica composite material, its preparation method, and its application in treating wastewater containing rhodamine B. The composite material provided by this invention, when used to adsorb rhodamine B, exhibits advantages such as rapid adsorption, high adsorption capacity, and low degradation rate with repeated use.

[0007] The first aspect of this invention provides a method for preparing a cerium dioxide-silica composite material, comprising the following steps:

[0008] (1) Mix choline chloride with cerium salt and heat to react to obtain a mixture;

[0009] (2) Add tetraethyl orthosilicate to the mixture in step (1), stir and react, then dry and calcine to obtain cerium dioxide-silica composite material.

[0010] Furthermore, the cerium salt mentioned in step (1) is at least one of cerium nitrate hexahydrate, cerium chloride heptahydrate, etc.

[0011] Furthermore, the choline chloride and / or cerium salt mentioned in step (1) can be commercially available products, and if the commercially available products contain a mixture of choline chloride and cerium salt, they can also be used directly.

[0012] Furthermore, the molar ratio of choline chloride to cerium salt in step (1) is 1:1-2.

[0013] Furthermore, in step (1), the temperature for mixing choline chloride and cerium salt is 65-95℃, preferably 75-85℃. The mixing can be carried out under stirring conditions, and there are no special requirements for the stirring method and speed, as long as it can ensure that choline chloride and cerium salt are fully mixed.

[0014] Furthermore, the tetraethyl orthosilicate mentioned in step (2) is a commercially available product. Preferably, a solution containing tetraethyl orthosilicate is used, wherein the mass fraction of tetraethyl orthosilicate in the solution is 60%-80%, more preferably 65%-75%.

[0015] Furthermore, the ratio of the amount of tetraethyl orthosilicate used in step (2) to the mass ratio of the mixture in step (1) is 2-5:1.

[0016] Further, in step (2), tetraethyl orthosilicate or a solution containing tetraethyl orthosilicate is added to the mixture in step (1). The addition process can be done in one go or multiple times, and the multiple additions are generally 2-5 times.

[0017] Furthermore, the stirring reaction time in step (2) is 10-80 minutes, preferably 30-60 minutes.

[0018] Further, the drying temperature in step (2) is 100-150℃, preferably 125-135℃; the drying time is 1-7h, preferably 4-6h.

[0019] Further, the roasting temperature in step (2) is 450-700℃, preferably 500-600℃; the roasting time is 0.5-4h, preferably 1.5-2.5h.

[0020] A second aspect of this invention provides a cerium dioxide-silica composite material prepared using the method described above. The cerium dioxide-silica composite material, by weight, contains 5%-40% cerium dioxide.

[0021] The third aspect of the present invention provides the application of the cerium dioxide-silica composite material prepared by the above method as an adsorbent in the treatment of wastewater containing Rhodamine B.

[0022] Furthermore, in the application described in this invention, the content of Rhodamine B in the water is generally less than 50 mg / L, preferably 20-40 mg / L, and the adsorbent is added at a mass ratio of 1:10-30 to Rhodamine B.

[0023] Furthermore, in the application described in this invention, the processing temperature is 25-35°C, and the processing time is 15-30 minutes.

[0024] Furthermore, in the application described in this invention, the regeneration conditions after the cerium dioxide-silica composite material is saturated with adsorption are as follows: the regeneration is carried out in an oxygen-containing atmosphere, such as in an air atmosphere; the regeneration temperature is 300-450℃, preferably 360-420℃, and the regeneration time is 30-50 minutes, preferably 30-45 minutes.

[0025] Compared with the prior art, the cerium dioxide-silica composite material of the present invention, its preparation method, and its application in the treatment of Rhodamine B-containing wastewater have the following effects:

[0026] (1) Choline chloride mixed with cerium salt was used as the cerium source, which has a better interaction with tetraethyl orthosilicate. On the one hand, this overcomes the shortcoming of easy agglomeration of nano-cerium dioxide and obtains nano-cerium dioxide with better dispersibility; on the other hand, it increases the density of oxygen defect sites per unit area of ​​cerium dioxide, which helps to improve its catalytic performance and facilitates regeneration. The final composite material has excellent adsorption effect on rhodamine B, and can achieve a removal rate of more than 85% of rhodamine B within 30 minutes.

[0027] (2) Choline chloride and cerium salt can form quaternary ammonium salt, which can make quaternary ammonium groups exist on the surface or in the pores of silica. It is easy to form CH…Π with the Π bond of Rhodamine B. While improving the adsorption performance of the material for Rhodamine B, it is easy to restore the activity through regeneration. It can be recycled multiple times, thus improving the service life.

[0028] (3) The cerium dioxide-silica composite material of the present invention is used as an adsorbent to treat wastewater containing rhodamine B. It not only has rapid adsorption and large adsorption capacity, but also easily restores adsorption performance through catalytic oxidation regeneration treatment and has a low decay rate when recycled. Detailed Implementation

[0029] The cerium dioxide-silica composite material of the present invention, its preparation method, and its application effects are further described in detail below with reference to specific embodiments. The embodiments are implemented based on the technical solution of the present invention, and detailed implementation methods and specific operating procedures are given; however, the scope of protection of the present invention is not limited to the following embodiments.

[0030] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods in the art. Unless otherwise specified, the experimental materials used in Example 1 were purchased from conventional biochemical reagent stores. In the context of this invention, unless otherwise specified, all percentages (%) refer to mass percentages.

[0031] Example 1

[0032] (1) Choline chloride and cerium nitrate hexahydrate are mixed and reacted at 80°C to obtain a mixture, wherein the molar ratio of choline chloride to cerium nitrate hexahydrate is 1:1.

[0033] (2) Add tetraethyl orthosilicate to distilled water and stir to prepare a solution containing tetraethyl orthosilicate, wherein the mass fraction of tetraethyl orthosilicate is 69%. Add the solution containing tetraethyl orthosilicate to the mixture in step (1) at one time, with the mass ratio of tetraethyl orthosilicate to the mixture in step (1) being 2:1. Stir and react for 30 minutes, dry at 130℃ for 5 hours, and calcine at 550℃ for 2 hours to obtain the cerium dioxide-silica composite material.

[0034] Based on the weight of the composite material, the cerium dioxide content is 35% by mass.

[0035] Example 2

[0036] (1) Choline chloride and cerium nitrate hexahydrate are mixed and reacted at 70°C to obtain a mixture, wherein the molar ratio of choline chloride to cerium nitrate hexahydrate is 1:2.

[0037] (2) Add tetraethyl orthosilicate to distilled water and stir to prepare a solution containing tetraethyl orthosilicate, wherein the mass fraction of tetraethyl orthosilicate is 60%. Add the solution containing tetraethyl orthosilicate to the mixture in step (1) at one time, the mass ratio of tetraethyl orthosilicate to the mixture in step (1) is 2:1, stir and react for 45 minutes, dry at 100℃ for 7 hours, and calcine at 500℃ for 3 hours to obtain the cerium dioxide-silica composite material.

[0038] Based on the weight of the composite material, the cerium dioxide content is 37% by mass.

[0039] Example 3

[0040] (1) Choline chloride and cerium nitrate hexahydrate are mixed and reacted at 90°C to obtain a mixture, wherein the molar ratio of choline chloride to cerium nitrate hexahydrate is 1:1.5.

[0041] (2) Add tetraethyl orthosilicate to distilled water and stir to prepare a solution containing tetraethyl orthosilicate, wherein the mass fraction of tetraethyl orthosilicate is 77%. Add the solution containing tetraethyl orthosilicate to the mixture in step (1) at one time, with the mass ratio of tetraethyl orthosilicate to the mixture in step (1) being 2:1. Stir and react for 50 minutes, dry at 150℃ for 2 hours, and calcine at 650℃ for 1 hour to obtain the cerium dioxide-silica composite material.

[0042] Based on the weight of the composite material, the cerium dioxide content is 36% by mass.

[0043] Example 4

[0044] The preparation process and conditions in this embodiment are basically the same as in Example 1, except that the mass ratio of tetraethyl orthosilicate in the solution to the mixture in step (1) is 4:1, while other reaction conditions and preparation processes remain unchanged, thus obtaining the cerium dioxide-silica composite material. Based on its weight, the cerium dioxide mass content is 21%.

[0045] Example 5

[0046] The preparation process and conditions in this embodiment are basically the same as in Example 1, except that cerium chloride heptahydrate is used as the cerium salt, and the amount remains the same, ultimately yielding a cerium oxide-silica composite material. Based on its weight, the cerium dioxide content is 37%.

[0047] Example 6

[0048] The preparation process and conditions in this embodiment are basically the same as in Example 1, except that the tetraethyl orthosilicate aqueous solution is added to the mixture in step (1) in five separate additions. The final product is a cerium dioxide-silica composite material. Based on its weight, the cerium dioxide content is 32%.

[0049] Comparative Example 1

[0050] Same as Example 1, except that: using conventional preparation method, 1.3g of cerium nitrate hexahydrate and sodium hydroxide were added to 12.4mL of distilled water and stirred to prepare cerium nitrate solution. 13.4mL of tetraethyl orthosilicate was added to cerium nitrate solution and stirred at room temperature for 30 minutes. After drying at 130℃ for 5 hours, it was calcined at 500℃ for 2 hours to finally obtain cerium dioxide-silica composite material.

[0051] Comparative Example 2

[0052] Same as Example 1, except that 1-ethyl-3-methylimidazole chloride was used instead of choline chloride to finally obtain cerium dioxide-silica composite material.

[0053] Comparative Example 3

[0054] Same as Example 1, except that: in step (1), choline chloride and cerium nitrate hexahydrate were not mixed beforehand, but choline chloride and cerium nitrate hexahydrate were directly mixed with tetraethyl orthosilicate solution, with the same amount of feed, and finally cerium dioxide-silica composite material was obtained.

[0055] Comparative Example 4

[0056] Same as Example 1, except that in step (a), ferric nitrate nonahydrate is used instead of cerium nitrate hexahydrate, and the amount of feed is the same, and ferric oxide-silica composite material is finally obtained.

[0057] Test case

[0058] The performance of the composite material in treating Rhodamine B in water was evaluated using a static adsorption method. The concentration of Rhodamine B in the water to be treated was 30 mg / L. Adsorbent materials prepared in Examples 1-6 and Comparative Examples 1-4 were added at a mass ratio of the composite material to Rhodamine B in the water of 1:30. The mixture was continuously shaken at 160 rpm at 25°C for 30 minutes to reach adsorption equilibrium. After centrifugation, the supernatant was collected, and the absorbance was measured at 553 nm using a UV spectrophotometer (WFZ UV-2000). The formula for calculating the Rhodamine B removal rate in water is as follows:

[0059]

[0060] In the formula, H represents the removal rate of Rhodamine B in water, and A0 and A e (mg / L) represents the absorbance values ​​of Rhodamine B solution before and after treatment, respectively.

[0061] After adsorption saturation, the material was collected by centrifugation and regenerated by heating at 380°C for 40 minutes in an air atmosphere at a flow rate of 30 mL / min in a tube furnace.

[0062] Table 1 Static adsorption results and regeneration effect

[0063]

Claims

1. A method for preparing a cerium dioxide-silica composite material, characterized in that... The process includes the following steps: (1) mixing choline chloride with cerium salt and heating to react to obtain a mixture; (2) adding tetraethyl orthosilicate to the mixture in step (1), stirring to react, and then drying and calcining to obtain a cerium dioxide-silica composite material.

2. The method according to claim 1, characterized in that: The cerium salt mentioned in step (1) is at least one of cerium nitrate hexahydrate and cerium chloride heptahydrate.

3. The method according to claim 1 or 2, characterized in that: The molar ratio of choline chloride to cerium salt in step (1) is 1:1-2.

4. The method according to claim 1, characterized in that: In step (1), the temperature at which choline chloride and cerium salt are mixed is 65-95℃, preferably 75-85℃.

5. The method according to claim 1, characterized in that: The tetraethyl orthosilicate mentioned in step (2) is a solution containing tetraethyl orthosilicate, wherein the mass fraction of tetraethyl orthosilicate in the solution is 60%-80%, preferably 65%-75%.

6. The method according to claim 1 or 5, characterized in that: In step (2), the amount of tetraethyl orthosilicate used is in a mass ratio of 2-5:1 to the mass of the mixture in step (1).

7. The method according to claim 1, characterized in that: In step (2), tetraethyl orthosilicate or a solution containing tetraethyl orthosilicate is added to the mixture in step (1). The addition process may be done once or multiple times, and the multiple additions are generally 2-5 times.

8. The method according to claim 1, characterized in that: The stirring reaction time in step (2) is 10-80 minutes, preferably 30-60 minutes.

9. The method according to claim 1, characterized in that: The drying temperature in step (2) is 100-150℃, preferably 125-135℃; the drying time is 1-7h, preferably 4-6h.

10. The method according to claim 1, characterized in that: The roasting temperature in step (2) is 450-700℃, preferably 500-600℃; the roasting time is 0.5-4h, preferably 1.5-2.5h.

11. A cerium dioxide-silica composite material, characterized in that... It is prepared by the method described in any one of claims 1-10.

12. The application of the cerium dioxide-silica composite material prepared by the method of any one of claims 1-10 or the composite material of claim 11 as an adsorbent in the treatment of wastewater containing Rhodamine B.

13. The application according to claim 12, characterized in that: The content of Rhodamine B in water is generally less than 50 mg / L, preferably 20-40 mg / L, and the adsorbent is added at a mass ratio of 1:10-30 to Rhodamine B.

14. The application according to claim 12, characterized in that: The processing temperature is 25-35℃, and the processing time is 15-30 minutes.

15. The application according to claim 12, characterized in that: The regeneration conditions for cerium dioxide-silica composite material after adsorption saturation are as follows: the regeneration is carried out in an oxygen-containing atmosphere, preferably in an air atmosphere; the regeneration temperature is 300-450℃, preferably 360-420℃, and the regeneration time is 30-50 minutes, preferably 30-45 minutes.

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