A novel method for preparing three-dimensional ceramsite

Abstract

This invention discloses a novel three-dimensional ceramsite, belonging to the field of new materials technology. The invention proposes an intrapore three-dimensional growth technology to transfer silicon and aluminum elements from the bulk phase of the ceramsite into the pores, resulting in a three-dimensional morphology and a novel ceramsite with significantly improved performance. The intrapore growth technology for obtaining novel three-dimensional adsorption ceramsite is simple in process and operation, and has low preparation cost. Furthermore, the novel ceramsite prepared by this method possesses both high adsorption and separation performance, significantly improving adsorption performance and applicability. It has broad application prospects in the removal or passivation of pollutants in environments such as CO2 sequestration, wastewater treatment, and contaminated soil. In addition, wastewater generated in each stage of the process can be reused in other processes, with no sewage discharge, achieving a closed-loop material flow throughout the entire process, effectively saving resources and protecting the environment.

Description

Technical Field

[0001] This invention belongs to the field of new materials technology, specifically relating to a method for preparing a novel three-dimensional ceramsite. Background Technology

[0002] As an environmentally friendly material, ceramsite has shown great application potential in the field of water treatment due to its abundant raw material sources, low cost, and unique porous structure, especially in the removal of ammonia nitrogen, heavy metals, and organic pollutants from water bodies. However, although ceramsite possesses basic adsorption properties, its limited specific surface area and the number of adsorption sites severely restrict further improvement of its adsorption capacity, thus limiting its widespread application in water treatment.

[0003] To overcome this technical bottleneck, researchers have been continuously exploring methods to improve the adsorption performance of ceramsite, including elemental doping, coating, and hydrothermal modification. Among these, hydrothermal modification technology, which utilizes the silicon and aluminum elements within the ceramsite itself to generate zeolite phases within the pores, significantly increases the specific surface area and adsorption sites, becoming an effective way to enhance the adsorption performance of ceramsite. The microporous structure of zeolite provides abundant adsorption sites for pollutants, resulting in a significant increase in the adsorption capacity of the ceramsite.

[0004] However, existing hydrothermal modification technologies, while achieving zeolite-based modification of ceramsite, also face significant challenges. The newly formed zeolite layer on the pore walls of the ceramsite becomes a key factor affecting adsorption performance. On the one hand, an excessively thin zeolite layer leads to insufficient zeolite loading, limiting the improvement in adsorption capacity; on the other hand, while an excessively thick zeolite layer can increase adsorption capacity, it can clog pores, reduce pore permeability, and increase diffusion resistance in the microporous structure, resulting in a decrease in adsorption rate and a prolonged adsorption equilibrium time. This contradiction makes it difficult for existing processes to achieve a balance between increasing adsorption capacity and maintaining a high adsorption rate. Summary of the Invention

[0005] To address the aforementioned technical issues, this invention abandons the traditional method of flat-laying zeolite growth on the pore walls of ceramsite and proposes a three-dimensional growth technique within the pores. This technique involves embedding zeolite into the pore walls of ceramsite and allowing it to grow into the pore space. This fully utilizes the space within the ceramsite pores, reduces dependence on the pore wall area, and increases the zeolite loading capacity. Simultaneously, the three-dimensionally grown zeolite significantly shortens the pollutant transport path and reduces diffusion resistance, which is beneficial for increasing the adsorption rate and reducing the adsorption time, thereby improving the efficiency of ceramsite as an adsorbent.

[0006] To achieve the above-mentioned technical effects, the present invention is implemented through the following technical solution: a method for preparing a novel three-dimensional ceramsite, comprising the following steps:

[0007] S1: Immerse the ceramsite in alkaline solution A and gently stir for 0.5 to 2 hours under heating conditions of 40℃~100℃; the resulting leachate is solution B. Wash the ceramsite several times with deionized water and dry it for later use.

[0008] S2: Mix alkyl quaternary ammonium salt and alcohol in a ratio of 1:(11-82) and stir to obtain solution C; Immerse the ceramic particles obtained in S1 into solution C and stir continuously for 5-30 minutes to obtain mixture D;

[0009] S3: Mix the mixture D with the solution B to obtain the mixture E. Transfer E to the reactor and react at 100℃~200℃ for 2~12 hours. Then take out the ceramic particles, wash them repeatedly with deionized water and dry them to obtain a new type of ceramic particles with a three-dimensional structure.

[0010] S4: Collect solution F of the washing wastewater from step S3, and collect the remaining reaction liquid G; reuse F in S1; reuse G in S2.

[0011] Furthermore, the alkaline solution includes caustic soda, soda ash, and potassium hydroxide, with a concentration of 1-5 mol / L and a solid-liquid ratio of 1:2-1:10;

[0012] Furthermore, the alkyl quaternary ammonium salt includes dodecyltrimethylammonium chloride and hexadecyltrimethylammonium bromide; the alcohol includes ethanol, glycerol, and ethylene glycol;

[0013] Furthermore, the ceramsite is a porous ceramsite, including but not limited to those prepared from clay, kaolin, sludge, slag, smelting slag, etc.

[0014] Furthermore, the silicon-to-aluminum ratio of the mixed system E is adjusted to 0.5–100 using silicon and aluminum salts.

[0015] The beneficial effects of this invention are:

[0016] 1) This invention uses in-pore growth technology to obtain a novel adsorption ceramic particle with a three-dimensional structure. The process steps and operation are simple and the preparation cost is low.

[0017] 2) The novel ceramsite prepared by this invention has both high adsorption and separation performance, which greatly improves the adsorption performance and the scope of application. It has broad application prospects in the removal or passivation of pollutants in environments such as CO2 storage, wastewater and polluted soil.

[0018] 3) Wastewater generated in each stage of the process implementation of this invention can be reused in other process stages, with no sewage discharge, realizing a closed loop of materials throughout the entire process, effectively saving resources and protecting the environment. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below.

[0020] Figure 1 This is a process flow diagram of the present invention;

[0021] Figure 2 This is the XRD pattern of the ceramsite prepared in Example 1 of this invention;

[0022] Figure 3 This is a scanning electron microscope image of the ceramic particles prepared in Example 1 of this invention;

[0023] Figure 4 This is the adsorption kinetic curve of heavy metal Ni on the ceramsite prepared in Example 1 of this invention.

[0024] Figure 5 This is the XRD pattern of the ceramsite prepared in Example 2 of this invention;

[0025] Figure 6 This is a scanning electron microscope image of the ceramic particles prepared in Example 2 of this invention;

[0026] Figure 7 This is the adsorption kinetic curve of Cu on the ceramsite obtained in Example 2 of the present invention;

[0027] Figure 8 This is a comparison of the adsorption kinetic curves of heavy metal Ni on the three-dimensional CHA-type ceramic particles obtained in Example 1 of the present invention and the conventional CHA ceramic particles obtained in Comparative Example 1. Detailed Implementation

[0028] Example 1

[0029] A novel method for preparing three-dimensional adsorption ceramsite includes the following steps:

[0030] S1: Immerse the ceramsite in a 2 mol / L potassium hydroxide solution (solid-liquid ratio 1:2.5) and gently stir for 1 hour under heating at 70℃; the resulting leachate is solution B. Wash the ceramsite several times with deionized water and dry it for later use.

[0031] S2: Dissolve dodecyltrimethylammonium bromide in ethanol (ratio 1:55) to obtain solution C; immerse the ceramic particles obtained in step S1 into solution C at a solid-liquid ratio of 1:2, and stir continuously for 10 minutes to obtain mixture D;

[0032] S3: Mix the mixture D with the solution B to obtain the mixture system E, and add silica to adjust the silicon-aluminum ratio of the system to 2-3. Then transfer E to the reactor and react at 100 degrees Celsius for 12 hours. Take out the ceramic particles, wash them several times with deionized water, and then dry them to obtain a new type of ceramic particles with a three-dimensional structure.

[0033] S4: Collect the washing wastewater from step S3 to obtain solution F, and collect the remaining reaction liquid G; reuse F in S1; reuse G in S2.

[0034] The novel ceramsite obtained based on the above process is further analyzed, such as... Figure 2 As shown, after testing and analysis, it is identified as CHA type ceramsite, and simultaneously composed of... Figure 3 It can be seen that the CHA grains are hexagonal rods with diameters ranging from tens to hundreds of nanometers, and aggregate to form a radial three-dimensional structure. The adsorption kinetics curve of the heavy metal Ni on these ceramic particles is shown below. Figure 4 As shown in the figure, the ceramsite can achieve a 90% Ni removal rate in less than 30 minutes.

[0035] Example 2

[0036] A novel method for preparing three-dimensional adsorption ceramsite includes the following steps:

[0037] S1: Immerse commercially available ceramsite in 3 mol / L sodium hydroxide solution (solid-liquid ratio 1:5) and gently stir for 1.5 hours under heating at 50°C; the resulting leachate is solution B. Wash the resulting ceramsite several times with deionized water and dry it for later use.

[0038] S2: Dissolve dodecyltrimethylammonium bromide in an alcohol solution (alkyl quaternary ammonium salt to alcohol ratio of 1:11) to obtain solution C; immerse the ceramic particles obtained in S1 into solution C at a solid-liquid ratio of 1:1 and stir continuously for 20 minutes to obtain mixture D;

[0039] S3: Mix the mixture D with the solution B to obtain the mixture system E. Use sodium silicate to adjust the silicon-aluminum ratio of the system to about 0.5 to 1.5. Transfer E to the reactor and react at 150 degrees Celsius for 8 hours. Take out the ceramic particles, wash them several times with deionized water, and then dry them to obtain a new type of ceramic particles with a three-dimensional structure.

[0040] S4: Collect the washing wastewater from step S3 to obtain solution F, and collect the remaining reaction liquid G; reuse F in S1; reuse G in S2.

[0041] like Figure 5 As shown, the tested material is FAU type ceramsite, and it is also composed of... Figure 6 It can be seen that its morphology is radial; in addition, as Figure 7As shown, it exhibits excellent adsorption performance for the heavy metal Cu, with an adsorption capacity 3.4 times that of the original ceramsite, and the time required to reach 90% adsorption is reduced by nearly 30% compared to the original ceramsite. This is due to two main reasons: firstly, the three-dimensional FAU-type ceramsite transforms the Si and Al elements in the ceramsite channels into FAU zeolite, resulting in a richer pore structure and more adsorption sites, thus exhibiting higher heavy metal adsorption performance; secondly, the dissolution process of Si and Al elements in the ceramsite widens the original pores, facilitating diffusion. Furthermore, the three-dimensional radial distribution and morphology of FAU zeolite in the ceramsite channels significantly reduces the diffusion resistance of heavy metal ions, thereby improving mass transfer efficiency.

[0042] Comparative Example 1

[0043] In Example 1, solution C in step S2 was changed to a deionized aqueous solution, while the remaining steps remained unchanged, thus obtaining conventional CHA ceramsite. The adsorption kinetics curves of the three-dimensional CHA-type ceramsite obtained in this invention and conventional CHA ceramsite for the heavy metal Ni were measured under the same test conditions, as shown below. Figure 8 As shown in the figure, the three-dimensional CHA-type ceramic particles obtained by this invention have a higher removal rate of heavy metal Ni than traditional CHA ceramic particles, and the adsorption speed is also superior: traditional CHA-type ceramic particles require more than 12 hours to reach 90% equilibrium adsorption capacity, while the three-dimensional CHA ceramic particles obtained by this invention can reach this level in only half an hour. This time is shortened by 95.8% compared with traditional CHA-type ceramic particles, and the adsorption performance has achieved a qualitative leap.

[0044] The preferred embodiments of the present invention disclosed above are only for the purpose of illustrating the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation described.

Claims

1. A method for preparing a novel three-dimensional ceramsite, characterized in that, Includes the following steps: S1: Immerse the ceramsite in alkaline solution A and gently stir for 0.5 to 2 hours under heating conditions of 40℃ to 100℃; the resulting leachate is solution B, and the resulting ceramsite is washed several times with deionized water and dried for later use; the alkaline solution includes caustic soda, soda ash or potassium hydroxide, with a concentration of 1 to 5 mol / L and a solid-liquid ratio of 1:2 to 1:10; S2: Mix alkyl quaternary ammonium salt and alcohol in a ratio of 1:(11~82) and stir to obtain solution C; Immerse the ceramic particles obtained in S1 into solution C and stir continuously for 5~30 minutes to obtain mixture D; S3: Mix the mixture D with the solution B to obtain the mixture E. Transfer E to the reactor and react at 100℃~200℃ for 2~12 hours. Then take out the ceramic particles, wash them repeatedly with deionized water and dry them to obtain a new type of ceramic particles with a three-dimensional structure. The silicon and aluminum elements in the pores of the ceramsite are transformed into zeolite; S4: Collect solution F of the washing wastewater from step S3, and collect the remaining reaction liquid G; reuse F in S1; reuse G in S2.

2. The method for preparing a novel three-dimensional ceramsite according to claim 1, characterized in that, The alkyl quaternary ammonium salt includes dodecyltrimethylammonium chloride or hexadecyltrimethylammonium bromide; the alcohol includes ethanol, glycerol or ethylene glycol.

3. The method for preparing a novel three-dimensional ceramsite according to claim 1, characterized in that, The ceramsite is a porous ceramsite, which may be prepared from clay, kaolin, sludge, slag or smelting slag as raw materials, including but not limited to those prepared from clay, kaolin, sludge, slag or smelting slag.

4. The method for preparing a novel three-dimensional ceramsite according to claim 1, characterized in that, The silicon-to-aluminum ratio of the mixed system E is adjusted to 0.5-100 using silicon and aluminum salts.

5. The application of the ceramsite prepared by the method for preparing a novel three-dimensional ceramsite as described in any one of claims 1-4 in the adsorption of heavy metals.

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