Microporous carbon-coated MCM-41 core-shell composite adsorption material based on coal gasification ash as well as preparation method and application of microporous carbon-coated MCM-41 core-shell composite adsorption material
By preparing microporous carbon@MCM-41 core-shell composite adsorbent material, the problems of coal gasification ash slag resource recovery and water pollutant adsorption were solved, achieving efficient adsorption of hexavalent chromium and organic dyes, reducing costs and simplifying the process.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA UNIV OF MINING & TECH
- Filing Date
- 2026-03-23
- Publication Date
- 2026-04-21
AI Technical Summary
Existing technologies are insufficient for effectively recovering carbon and silicon resources from coal gasification ash, and activated carbon and mesoporous silicon materials suffer from disordered pore structures and limited adsorption capacity in the field of water pollutant adsorption.
Microporous carbon@MCM-41 core-shell composite adsorbent material was prepared by acid-base separation treatment of coal gasification ash residue. The ordered mesoporous shell layer of MCM-41 was coated on the surface of the carbon material in situ to construct a composite adsorbent material with tunable pore structure.
The material achieves the synergistic high-value utilization of carbon and silicon resources in coal gasification ash residue. It exhibits good adsorption and removal performance for hexavalent chromium and organic dyes. The process is simple and low-cost.
Smart Images
Figure CN121892104A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of solid waste resource utilization and water pollution control technology, specifically relating to a microporous carbon@MCM-41 core-shell composite adsorbent material based on coal gasification ash and its preparation method. Background Technology
[0002] Coal gasification technology is an important way to utilize coal cleanly and efficiently, but it generates a large amount of coal gasification ash and slag byproducts during the gasification process. Statistics show that my country produces more than 60 million tons of coal gasification ash and slag annually, and this figure is increasing year by year. These ash and slag products are characterized by large production volumes, high stockpiles, and significant environmental risks, and have become a bottleneck restricting the sustainable development of the coal chemical industry.
[0003] The main components of coal gasification ash are silicon dioxide (SiO2), aluminum oxide (Al2O3), calcium oxide (CaO), iron oxide (Fe2O3), and residual carbon. However, due to its dense structure and complex composition, its utilization rate for high-value purposes is relatively low.
[0004] In existing technologies, coal gasification ash is mostly treated through simple landfilling or low-value utilization, making it difficult to simultaneously achieve resource recovery and pollution control. On the other hand, activated carbon and mesoporous silica materials have wide applications in the adsorption of water pollutants, but the former has a disordered pore structure and its mass transfer behavior is difficult to control, while the latter has limited surface adsorption capacity.
[0005] Therefore, there is an urgent need for a method to prepare composite adsorbent materials that can simultaneously recover carbon and silicon resources from coal gasification ash and slag, and that have tunable pore structure, high adsorption performance and good mass transfer characteristics. Summary of the Invention
[0006] The purpose of this invention is to provide a method for preparing a carbon-silicon composite adsorbent material with an tunable pore structure, using coal gasification ash as raw material, obtaining carbon material and silicon source through acid-base separation, and in-situ coating the carbon material surface with an ordered mesoporous shell layer of MCM-41, and the application of this material in the adsorption and removal of hexavalent chromium and organic dyes. This method does not require precise adjustment of the silicon source concentration, is simple in process, and low in cost, enabling the synergistic high-value utilization of carbon and silicon resources in coal gasification ash. The resulting composite adsorbent material has a microporous-mesoporous synergistic structure and exhibits good adsorption and removal performance for hexavalent chromium and methylene blue in water.
[0007] The purpose of this invention is to provide a microporous carbon@MCM-41 core-shell composite adsorbent material based on coal gasification ash. The composite adsorbent material has a core-shell structure with a microporous carbon core and a hexagonal ordered MCM-41 mesoporous silica shell. The carbon matrix is an amorphous carbon structure, and the MCM-41 mesoporous silica shell is an amorphous mesoporous structure with adjustable shell thickness. The MCM-41 mesoporous silica shell is continuously and in-situ coated on the surface of the microporous carbon. The material exhibits an irregular particle agglomeration morphology, with a nanoscale mesoporous silica rough coating layer on the particle surface and a porous structure between the particles.
[0008] Furthermore, the composite adsorbent material exhibits characteristic diffraction peaks of the MCM-41 crystal plane in the small-angle X-ray diffraction region at 1.65-2.55°, with high peak intensity and regular peak shape; the wide-angle X-ray diffraction region shows amorphous carbon broad diffuse peaks at 20°-25°, with no impurity crystalline phase diffraction peaks.
[0009] The second objective of this invention is to provide a method for preparing a microporous carbon@MCM-41 core-shell composite adsorbent material based on coal gasification ash, comprising the following steps:
[0010] (1) The coal gasification ash residue is mixed with an alkaline activator and then subjected to high-temperature alkaline activation treatment to obtain alkaline activated residue;
[0011] (2) The alkaline activated residue is subjected to acid washing treatment with an acidic solution, and the residue is filtered to obtain the acid washing residue;
[0012] (3) The pickling residue is subjected to alkaline leaching with sodium hydroxide solution, and filtered to obtain silicon-rich alkaline leaching filtrate and alkaline leached carbon material;
[0013] (4) The alkaline-impregnated carbon material is subjected to oxidation treatment to obtain carbon oxide material;
[0014] (5) Using the silicon-rich alkaline leaching solution as a silicon source, in the presence of a template agent, the MCM-41 mesoporous silicon shell layer is grown in situ on the surface of the carbon oxide material to form a coating structure.
[0015] (6) The template agent was removed by solvent extraction to obtain microporous carbon@MCM-41 composite adsorbent material.
[0016] Further, in step (1), the coal gasification ash is ground and sieved to below 200 mesh, and then mixed with an alkaline activator; the alkaline activation treatment in step (1) is: the coal gasification ash is mixed with sodium carbonate at a mass ratio of 1:0.5-1.5 and calcined at 750-900℃ for 1-3 hours.
[0017] Further, the acidic solution in step (2) is selected from one or more of hydrochloric acid, sulfuric acid or nitric acid, with an acid concentration of 1-4 mol / L, a treatment temperature of 60-90℃, and a treatment time of 1-3 h.
[0018] Furthermore, in step (3), the concentration of the sodium hydroxide solution is 2-6 mol / L, the treatment temperature is 70-95℃, and the treatment time is 2-6 h.
[0019] Further, in step (4), the oxidation treatment step is as follows: the alkaline-impregnated carbon material is added to a hydrogen peroxide solution for oxidation treatment, the concentration of the hydrogen peroxide solution is 20-35 wt%, the oxidation treatment temperature is 40-70°C, and the oxidation treatment time is 1-4 h.
[0020] Further, the template agent in step (5) is hexadecyltrimethylammonium bromide, the pH of the reaction system is 9-11, the hydrothermal reaction temperature is 100-150 ℃, and the reaction time is 24-48 h; the mass ratio of the template agent, carbon oxide material and silicon source is 1:0.24-0.81:0.82, wherein the silicon source is SiO2.
[0021] Furthermore, the solvent extraction method in step (6) is to use an ethanol-hydrochloric acid mixed solution to perform solvent extraction treatment on the template agent.
[0022] A third objective of this invention is to provide the application of the aforementioned composite adsorbent material in the removal of pollutants from water bodies, including hexavalent chromium and methylene blue.
[0023] Compared with the prior art, the present invention has the following beneficial effects:
[0024] 1. Low raw material cost, enabling the synergistic high-value utilization of carbon and silicon resources in coal gasification ash residue, turning waste into treasure;
[0025] 2. An integrated process route of "acid washing-alkali leaching-silicon-carbon separation-in-situ coating" has been established. The process flow is simple and suitable for large-scale and industrial applications.
[0026] 3. By adjusting the amount of carbon oxide added, the shell thickness of the microporous carbon@MCM-41 core-shell composite material can be controlled, thereby obtaining composite materials with different mass transfer characteristics and adsorption performance. Among them, the thin-shell sample showed better performance in the adsorption of pollutants in water. Attached Figure Description
[0027] Figure 1 This is a schematic diagram of the preparation process of the composite adsorption material of the present invention;
[0028] Figure 2 Small-angle and wide-angle XRD diffraction patterns of the thick-shell microporous carbon@MCM-41 composite adsorbent material;
[0029] Figure 3SEM image of thick-shell microporous carbon@MCM-41 composite adsorbent material;
[0030] Figure 4 This diagram illustrates the comparison of the adsorption capacity of microporous carbon@MCM-41 composite adsorbents with different shell thicknesses for typical pollutants under the same conditions.
[0031] Figure 2 and Figure 3 Using thick-shell samples as an example, the ordered mesoporous shell layer and continuous coating morphology of the core-shell composite material of this invention are characterized and described. It should be noted that the thick-shell samples are mainly used to demonstrate the typical morphological features of the core-shell structure successfully constructed in this invention, and do not represent the optimal solution for adsorption applications. Detailed Implementation
[0032] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings, but the present invention is not limited to the following embodiments.
[0033] Example 1
[0034] like Figure 1 As shown in the figure, this embodiment provides a method for preparing microporous carbon@MCM-41 core-shell composite adsorbent material from coal gasification ash residue. The specific steps are as follows:
[0035] (1) Alkali activation treatment of coal gasification ash residue
[0036] The coal gasification ash residue was crushed and ground to below 200 mesh. 100 g of the residue was weighed and mixed with sodium carbonate at a mass ratio of 1:1. The mixture was then placed in a tube furnace and activated at 850 °C under a nitrogen atmosphere for 2 h. After natural cooling to room temperature, the alkali-activated residue was obtained.
[0037] (2) Pickling to remove impurities
[0038] Add the alkali-activated residue to a 2 mol / L hydrochloric acid solution and mix at a solid-liquid ratio of 1:15 g / mL. Stir and react at 90 °C for 2 h. Filter and wash with deionized water until the filtrate is nearly neutral to obtain the acid-washed residue.
[0039] (3) Alkali leaching and separation of silicon and carbon materials
[0040] Add the pickling residue to a 3 mol / L NaOH solution and mix at a solid-liquid ratio of 1:15 g / mL. React at 90 °C for 1 h and separate by filtration: filtrate: silicon-rich alkaline leaching filtrate (sodium silicate solution), which is used as a silicon source; solid: alkaline-leached carbon material.
[0041] (4) Oxidative modification of carbon materials
[0042] The obtained alkaline-impregnated carbon material was added to a 30 wt% hydrogen peroxide solution and oxidized at 60 °C for 2 h to introduce oxygen-containing functional groups such as carboxyl and hydroxyl groups onto the carbon surface. After the reaction was completed, the material was filtered, washed, and dried to obtain the oxidized carbon material.
[0043] (5) In-situ growth of MCM-41 on carbon material surface
[0044] The silicon-rich alkaline leaching solution obtained in step (3) is used as the silicon source. The silicon element concentration in the silicon-rich alkaline leaching solution is about 5945 mg / L, which is equivalent to a SiO2 concentration of about 12.72 g / L. The following steps are followed:
[0045] 0.62 g of cetyltrimethylammonium bromide (CTAB) was dissolved in deionized water to form a template solution. Then, 40 mL of silicon-rich alkaline leaching solution was added as a silicon source and mixed evenly under stirring conditions. The corresponding SiO2 dosage was approximately 0.509 g, which allowed it to fully dissolve in the solution and form a uniform template system.
[0046] Add 0.5 g of carbon oxide material to the system and continue stirring to disperse it evenly;
[0047] The pH of the reaction system was adjusted to approximately 10.7 using sulfuric acid solution;
[0048] The resulting mixed solution was transferred to a polytetrafluoroethylene-lined closed reactor and subjected to a hydrothermal reaction at 150°C for 24 h to allow MCM-41 to grow in situ on the surface of the carbon oxide material to form a coating structure. After the reaction was completed, the mixture was naturally cooled to room temperature, filtered, and washed with deionized water until neutral to obtain a core-shell composite material precursor with MCM-41 coating.
[0049] (6) Shell thickness control
[0050] Under the same silicon source conditions, the shell thickness can be controlled by adjusting the amount of carbon oxide material added: reducing the amount of carbon oxide material results in a thick-shell core-shell composite adsorbent, while increasing the amount of carbon oxide material results in a thin-shell core-shell composite adsorbent. With the amounts of template agent and silicon source remaining essentially constant, the shell thickness of the core-shell composite material can be controllably adjusted by regulating the amount of carbon oxide material added. Specifically, the amount of template agent CTAB was fixed at 0.62 g, the silicon source (based on SiO2) was approximately 0.509 g, and the amounts of carbon oxide material added were 0.50 g, 0.30 g, and 0.15 g, respectively, corresponding to thin-shell, medium-shell, and thick-shell microporous carbon@MCM-41 core-shell composite materials. The results show that as the amount of carbon oxide material added decreases, i.e., the mass ratio of SiO2 to carbon oxide material increases from 1.02 to 3.39, the shell thickness of the resulting composite material gradually increases.
[0051] (7) Template removal
[0052] The obtained product was added to an ethanol-hydrochloric acid mixed solution with a volume ratio of 9:1 and a solid-liquid volume ratio of 10:1. The mixture was refluxed at 60 °C for 6 h to remove the CTAB template agent. It was then washed until neutral and dried at 80 °C to obtain the target microporous carbon@MCM-41 composite adsorbent material.
[0053] Figure 2 The results show that the thick-shell sample exhibits obvious diffraction peaks in the small-angle region, with the characteristic peaks near 1.65–2.55° corresponding to the (100) crystal plane diffraction peaks of MCM-41, indicating that the material has formed an ordered mesoporous silicon shell. In the wide-angle region, the sample shows broad diffuse peaks at 20–25°, corresponding to the characteristics of an amorphous carbon structure. The obvious small-angle diffraction peaks of this sample indicate that its shell coating is relatively complete, and it can be used as a representative sample of the successful construction of the core-shell structure of this invention.
[0054] Figure 3 The core-shell morphology of the thick-shell sample is shown. The sample exhibits an irregular granular aggregate structure, with a rough layer composed of nanoscale particles covering the particle surface. This rough layer is an in-situ grown mesoporous silica shell, indicating the successful construction of a core-shell structure. This sample can serve as a typical characterization sample for continuous shell structures.
[0055] Example 2
[0056] To evaluate the performance of the microporous carbon@MCM-41 composite adsorbent material of this invention in water pollution control, methylene blue (MB) and hexavalent chromium (Cr(VI)) were selected as typical organic dye pollutants and heavy metal anionic pollutants, respectively. Adsorption performance tests were conducted on samples with different shell thicknesses. The results showed that the thin-shell samples had adsorption capacities of 110.3 mg / g and 190.4 mg / g for methylene blue and hexavalent chromium, respectively; the medium-shell samples had adsorption capacities of 84.93 mg / g and 85.56 mg / g, respectively; and the thick-shell samples had adsorption capacities of 56.46 mg / g and 32.84 mg / g, respectively. Therefore, the adsorption performance of the material can be effectively controlled by adjusting the shell thickness. Thick-shell samples exhibit more complete coating, better shell continuity, and more typical core-shell morphology, making them more likely to successfully construct a core-shell structure. Thin-shell samples, due to their shorter mass transfer pathway and more fully exposed active sites on the carbon core surface, showed the best performance in adsorption applications, thus representing the preferred embodiment of this invention for the removal of pollutants from water bodies.
[0057] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.
Claims
1. A microporous carbon@MCM-41 core-shell composite adsorbent based on coal gasification ash, characterized in that, The composite adsorbent material has a core-shell structure with a microporous carbon core and a hexagonal ordered MCM-41 mesoporous silica shell. The carbon matrix is an amorphous carbon structure, and the MCM-41 mesoporous silica shell is an amorphous mesoporous structure with adjustable shell thickness. The MCM-41 mesoporous silica shell is continuously and in situ coated on the surface of the microporous carbon. The material exhibits an irregular particle agglomeration morphology, with a nanoscale mesoporous silica rough coating layer on the particle surface and a porous structure between the particles.
2. The microporous carbon@MCM-41 core-shell composite adsorbent material based on coal gasification ash as described in claim 1, characterized in that, The composite adsorbent material exhibits characteristic diffraction peaks of the MCM-41 crystal plane in the small-angle X-ray diffraction region at 1.65-2.55°, with high peak intensity and regular peak shape; the wide-angle X-ray diffraction region shows amorphous carbon broad diffuse peaks at 20°-25°, with no impurity crystalline phase diffraction peaks.
3. A method for preparing a microporous carbon@MCM-41 core-shell composite adsorbent material based on coal gasification ash, characterized in that, Includes the following steps: (1) The coal gasification ash residue is mixed with an alkaline activator and then subjected to high-temperature alkaline activation treatment to obtain alkaline activated residue; (2) The alkaline activated residue is subjected to acid washing treatment with an acidic solution, and the residue is filtered to obtain the acid washing residue; (3) The pickling residue is subjected to alkaline leaching with sodium hydroxide solution, and filtered to obtain silicon-rich alkaline leaching filtrate and alkaline leached carbon material; (4) The alkaline-impregnated carbon material is subjected to oxidation treatment to obtain carbon oxide material; (5) Using the silicon-rich alkaline leaching solution as a silicon source, in the presence of a template agent, the MCM-41 mesoporous silicon shell layer is grown in situ on the surface of the carbon oxide material to form a coating structure. (6) The template agent was removed by solvent extraction to obtain microporous carbon@MCM-41 composite adsorbent material.
4. The preparation method of the microporous carbon@MCM-41 core-shell composite adsorbent material based on coal gasification ash slag according to claim 3, characterized in that, In step (1), the coal gasification ash is ground and sieved to below 200 mesh, and then mixed with an alkaline activator; the alkaline activation treatment in step (1) is: the coal gasification ash is mixed with sodium carbonate at a mass ratio of 1:0.5-1.5 and calcined at 750-900℃ for 1-3 hours.
5. The preparation method of the microporous carbon@MCM-41 core-shell composite adsorbent material based on coal gasification ash slag according to claim 3, characterized in that, The acidic solution in step (2) is selected from one or more of hydrochloric acid, sulfuric acid or nitric acid, with an acid concentration of 1-4 mol / L, a treatment temperature of 60-90℃, and a treatment time of 1-3 h.
6. The preparation method of the microporous carbon@MCM-41 core-shell composite adsorbent material based on coal gasification ash as described in claim 3, characterized in that, The sodium hydroxide solution concentration in step (3) is 2-6 mol / L, the treatment temperature is 70-95℃, and the treatment time is 1-6 h.
7. The preparation method of microporous carbon@MCM-41 core-shell composite adsorbent material based on coal gasification ash slag according to claim 3, characterized in that, In step (4), the oxidation treatment step is as follows: the alkaline-impregnated carbon material is added to a hydrogen peroxide solution for oxidation treatment, the concentration of the hydrogen peroxide solution is 20-35 wt%, the oxidation treatment temperature is 40-70°C, and the oxidation treatment time is 1-4 h.
8. The preparation method of the microporous carbon@MCM-41 core-shell composite adsorbent material based on coal gasification ash as described in claim 3, characterized in that, The template agent mentioned in step (5) is hexadecyltrimethylammonium bromide, the pH of the reaction system is 9-11, the hydrothermal reaction temperature is 100-150 ℃, and the reaction time is 24-48 h; the mass ratio of the template agent, carbon oxide material and silicon source is 1:0.24-0.81:0.82, wherein the silicon source is SiO2.
9. The preparation method of the microporous carbon@MCM-41 core-shell composite adsorbent material based on coal gasification ash as described in claim 3, characterized in that, The solvent extraction method described in step (6) is to use an ethanol-hydrochloric acid mixed solution to perform solvent extraction on the template agent.
10. The application of the microporous carbon@MCM-41 core-shell composite adsorbent material based on coal gasification ash as described in claim 1 or 2 in the removal of pollutants from water bodies, wherein the pollutants include hexavalent chromium and methylene blue.