Multistage barrier sustained-release type nano-aluminum-based porous geopolymer building material
Patent Information
- Application Number
- CN202611107247.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-24
- Publication Date
- 2026-08-21
AI Technical Summary
然而，普通的纳米铝粉在地聚物的强碱性环境中反应剧烈，会瞬时大量释放气体，易引发气泡聚并、孔径粗化，最终以微米级大孔为主，难以稳定形成规整的纳米孔隙
针对普通纳米铝在制备多孔化地聚物建筑材料时存在的不足，本发明对纳米铝进行表面改性形成具有内、外包覆层的多级阻隔缓释型纳米铝，有效克服了上述问题。为此，本发明先利用等离子体将纳米铝表面改性处理，在去除了其表面的钝化氧化膜的同时活化成羟基层，而且避免了对纳米铝的损耗。然后本发明利用超临界CO2辅助柠檬酸-壳聚糖在纳米铝表面构建内改性包覆层，从而借助超临界CO2提供的气体高扩散性和液体溶解能力防止纳米铝表面的羟基脱落，使纳米铝保持良好分散性的同时，便于所述柠檬酸通过其多个羧基与纳米铝表面的氯离子形成六元螯合环，同时所述壳聚糖分子链通过氢键与所述柠檬酸交联构建形成柠檬酸-壳聚糖内改性包覆层。最后本发明利用光固化方式在所述改性包覆层表面形成由九氟己基三甲氧基硅烷水解产生的硅羟基与所述内改性包覆层中的羟基、氨基脱水缩合后连接而成的外改性包覆层。在此过程中，所述九氟己基三甲氧基硅烷在光引发剂产生的自由基作用下水解生成硅羟基（-Si-OH）的同时，还激发了所述内改性包覆层中柠檬酸-壳聚糖的羟基（-OH）和氨基（-NH2）的活性，从而使所述硅羟基与羟基、氨基脱水并缩合形成Si-O-C、Si-N共价键后构建所述外改性包覆层，同时还有利于防止九氟己基三甲氧基硅烷的自缩合导致包覆层失效的问题。采用本发明的改性纳米铝制备地聚物建筑材料时，在其高碱性环境中所述外改性包覆层发挥减缓氢氧根离子（OH-）进入的速率，而所述内改性包覆层中的酰胺键（-CONH-）、C-O-Al键与OH-反应，逐级控制防止过剩OH-进入后与纳米铝内核爆发式反应，从而使到达所述纳米铝内核的OH-均匀可控而且数量更加稳定，产生的纳米级气泡均匀稳定，再加上本发明的改性纳米铝具有良好的分散性，有效避免了分布不均、反应活性不均导致局部集中发泡诱发孔壁缺陷与连通孔隙，造成地聚物建筑材料的力学及耐久性能劣化的问题。
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Abstract
Description
Technical Field
[0001] This invention relates to the field of building materials technology, specifically to a multi-level barrier slow-release nano-aluminum-based porous geopolymer building material. Background Technology
[0002] The information disclosed in the background section of this invention is intended only to enhance the understanding of the overall background of this invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.
[0003] Geopolymers, as a type of low-carbon aluminosilicate cementitious material, possess advantages such as high strength, corrosion resistance, high temperature resistance, and low carbon footprint, making them highly promising for applications in thermal insulation, adsorption, and solid waste resource utilization. Porosity is a crucial development direction for the functionalization of geopolymers. Nanoscale pores play a decisive role in regulating the material's thermal insulation performance, adsorption capacity, permeability, and strength-toughness balance. High-performance nanoporous agents are the core key to the directional construction of uniform nanoporous structures.
[0004] Current methods for creating pores in geopolymers mainly include chemical foaming, physical gas entrainment, and sacrificial templates. Chemical foaming is the most widely used due to its simple process and strong controllability. Nano-aluminum powder, with its advantages of high gas production efficiency and readily available raw materials, has become a potential nano-foaming pore-forming material for geopolymer systems. However, ordinary nano-aluminum powder reacts violently in the strongly alkaline environment of geopolymers, releasing a large amount of gas instantaneously. This easily leads to bubble aggregation and pore size coarsening, ultimately resulting in predominantly micron-sized macropores, making it difficult to stably form regular nanopores. At the same time, a passivation oxide layer easily forms spontaneously on the surface of nano-aluminum powder, and the significant inter-particle agglomeration effect causes uneven reactivity and localized concentrated foaming, inducing pore wall defects and interconnected pores, which can easily lead to a significant deterioration in the mechanical and durability properties of geopolymer building materials. Summary of the Invention
[0005] To address the aforementioned problems, this invention proposes a multi-level barrier-resistant, slow-release nano-aluminum-based porous geopolymer building material. By modifying nano-aluminum, it generates an ultra-high content of nanopores within the geopolymer building material and effectively reduces harmful pores, thereby significantly improving the fire resistance and mechanical properties of the geopolymer building material. Specifically, the technical solution of this invention is as follows.
[0006] First, this invention provides a multi-level barrier slow-release nano-aluminum-based porous geopolymer building material, comprising the following components in the following proportions: 80-120 parts by weight of solid waste-based cementitious material, 32-48 parts by weight of potassium nepheline, 27-40 parts by weight of alkali activator, and 0.3-1.2 parts by weight of modified nano-aluminum powder. The modified nano-aluminum powder comprises a nano-aluminum core, the surface of which has a citric acid-chitosan inner modified coating layer formed by chelating citric acid with aluminum ions provided by the core through its carboxyl groups and cross-linking chitosan (β-(1→4)-2-amino-2-deoxy-D-glucose) molecular chains with the citric acid through hydrogen bonds. Simultaneously, it also has an outer modified coating layer formed by the dehydration condensation of silanol groups (-Si-OH) formed by the hydrolysis of nonafluorohexyltrimethoxysilane with the hydroxyl groups (-OH) and amino groups (-NH2) in the inner modified coating layer.
[0007] Furthermore, the solid waste-based cementitious material includes at least one of the following: fly ash, metakaolin, coal gangue powder, and mineral powder.
[0008] Furthermore, the alkaline activator includes at least one of potassium silicate, sodium silicate, etc.
[0009] Furthermore, the modified nano-aluminum powder is prepared using the following method: (1) Plasma treatment is performed on the surface-wetted nano-aluminum powder to obtain surface-activated nano-aluminum powder for later use.
[0010] (2) Prepare an ethanol aqueous solution containing chitosan and citric acid as an internal modification coating solution, mix it with the surface-activated nano-aluminum powder and react it in a supercritical CO2 environment. After completion, wash and dry the product to obtain nano-aluminum powder with a citric acid-chitosan internal modification coating layer for later use.
[0011] (3) Add a photoinitiator, an acidic external modification coating solution formed by nonafluorohexyltrimethoxysilane and anhydrous ethanol to the nano-aluminum powder with citric acid-chitosan internal modification coating layer, and then perform photo-treatment to obtain the modified nano-aluminum powder.
[0012] Furthermore, in step (1), the moisture content of the surface-wetted nano-aluminum powder is 5~15 wt.%.
[0013] Further, in step (1), the gas source for the plasma treatment is a mixture of argon (Ar) and oxygen (O2). Optionally, the volume ratio of argon to oxygen is 2~3:1.
[0014] Furthermore, in step (1), the power of the ion treatment is 100~150W and the time is 5~10min.
[0015] Further, in step (2), the mass ratio of chitosan, citric acid, and ethanol aqueous solution is 2~5g:6~10g:50~100g. Optionally, the mass fraction of the ethanol aqueous solution is 70~80%.
[0016] Further, in step (2), the internally modified coating solution is prepared by the following method: the chitosan is added to an ethanol aqueous solution, the pH of the system is adjusted to 4-5, stirred, and then citric acid is added and stirred until fully dissolved to obtain the internally modified coating solution. Optionally, the pH of the system can be adjusted by adding at least one of glacial acetic acid, citric acid, etc.
[0017] Further, in step (2), the ratio of the surface-activated nano-aluminum powder to the internally modified coating liquid is 1g:3~6mL.
[0018] Furthermore, in step (2), the reaction time is 15-30 min and the pressure is 10-25 MPa.
[0019] Furthermore, in step (2), the drying temperature is 45~60℃ and the time is 6~12 hours.
[0020] Furthermore, in step (3), the ratio of the nano-aluminum powder to the externally modified coating liquid is 1~3g:10mL.
[0021] Further, in step (3), the acidic pH is 4-5. Optionally, the pH can be adjusted by adding glacial acetic acid, citric acid, etc.
[0022] Further, in step (3), the photoinitiator is 10-20% of the mass of nonafluorohexyltrimethoxysilane. Optionally, the photoinitiator includes at least one of 2-hydroxy-2-methylphenylacetone, 1-hydroxycyclohexylphenyl ketone, and 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone.
[0023] Furthermore, in step (3), the light treatment time is 10~15 min.
[0024] Compared with the prior art, the technical solution of the present invention has at least the following beneficial effects: To address the shortcomings of ordinary nano-aluminum in the preparation of porous geopolymer building materials, this invention modifies the surface of nano-aluminum to form a multi-level barrier-free, slow-release nano-aluminum with inner and outer coatings, effectively overcoming the aforementioned problems. To this end, this invention first uses plasma to modify the surface of the nano-aluminum, removing the passivation oxide film while activating it into a hydroxyl layer, thus avoiding the loss of the nano-aluminum. Then, this invention utilizes supercritical CO2 to assist citric acid-chitosan in constructing an inner modified coating layer on the surface of the nano-aluminum. This leverages the high gas diffusion and liquid solubility provided by supercritical CO2 to prevent the hydroxyl groups on the nano-aluminum surface from detaching, maintaining good dispersibility of the nano-aluminum. Simultaneously, citric acid, through its multiple carboxyl groups, forms a six-membered chelate ring with chloride ions on the nano-aluminum surface, while the chitosan molecular chains crosslink with the citric acid through hydrogen bonds to form the citric acid-chitosan inner modified coating layer. Finally, this invention utilizes photocuring to form an outer modified coating layer on the surface of the modified coating layer. This outer modified coating layer is formed by the dehydration condensation of silanol groups generated from the hydrolysis of nonafluorohexyltrimethoxysilane with the hydroxyl and amino groups in the inner modified coating layer. During this process, while the nonafluorohexyltrimethoxysilane hydrolyzes to generate silanol groups (-Si-OH) under the action of free radicals generated by the photoinitiator, it also activates the activity of the hydroxyl groups (-OH) and amino groups (-NH2) of citric acid-chitosan in the inner modified coating layer. This allows the silanol groups to dehydrate and condense with the hydroxyl and amino groups to form Si-OC and Si-N covalent bonds, thus constructing the outer modified coating layer. This also helps prevent the coating layer from failing due to the self-condensation of nonafluorohexyltrimethoxysilane. When using the modified nano-aluminum of this invention to prepare geopolymer building materials, the outer modified coating layer plays a role in slowing down the reaction of hydroxide ions (OH-) in its highly alkaline environment. - The rate of entry, and the amide bonds (-CONH-), CO-Al bonds and OH in the internally modified coating layer - The reaction is controlled step by step to prevent excess OH. - Upon entering, it undergoes an explosive reaction with the nano-aluminum core, thereby causing the OH groups that reach the nano-aluminum core to... - The nanoscale bubbles produced are uniform, controllable, and more stable in quantity. In addition, the modified nano-aluminum of this invention has good dispersibility, which effectively avoids the problem of uneven distribution and uneven reactivity leading to local concentrated foaming that induces pore wall defects and interconnected pores, causing the mechanical and durability properties of geopolymer building materials to deteriorate. Attached Figure Description
[0025] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.
[0026] Figure 1 The image shows a modified nano-aluminum sample prepared in Example 1 below.
[0027] Figure 2 The image shows a scanning electron microscope (SEM) image of the modified nano-aluminum prepared in Example 1 below.
[0028] Figure 3 Porosity test diagram of the porous geopolymer building material prepared in Example 1 below.
[0029] Figure 4 The image shows a modified nano-aluminum sample prepared in Example 2 below.
[0030] Figure 5 The image shows a SEM image of the modified nano-aluminum prepared in Example 2 below.
[0031] Figure 6 Porosity test diagram of the porous geopolymer building material prepared in Example 2 below.
[0032] Figure 7 The image shows a modified nano-aluminum sample prepared in Example 3 below.
[0033] Figure 8 The image shows a SEM image of the modified nano-aluminum prepared in Example 3 below.
[0034] Figure 9 Porosity test diagram of the porous geopolymer building material prepared in Example 3 below.
[0035] Figure 10 The image shows the nano-aluminum powder sample used in Example 4 below.
[0036] Figure 11 The image below shows the SEM image of the nano-aluminum powder used in Example 4.
[0037] Figure 12 Porosity test diagram of the porous geopolymer building material prepared in Example 4 below.
[0038] Figure 13 The image shows an aluminum sample of nano-aluminum powder with a citric acid-chitosan internal modified coating used in Example 5 below.
[0039] Figure 14 The image below shows an SEM image of the nano-aluminum powder with a citric acid-chitosan internal modified coating used in Example 5.
[0040] Figure 15 Porosity test diagram of the porous geopolymer building material prepared in Example 5 below.
[0041] Figure 16 The image shows the modified nano-aluminum sample prepared in Example 6 below.
[0042] Figure 17The image shows a SEM image of the modified nano-aluminum prepared in Example 6 below.
[0043] Figure 18 Porosity test diagram of the porous geopolymer building material prepared in Example 6 below.
[0044] Figure 19 The image shows a modified nano-aluminum sample prepared in Example 7 below.
[0045] Figure 20 The image shows a SEM image of the modified nano-aluminum prepared in Example 7 below.
[0046] Figure 21 Porosity test diagram of the porous geopolymer building material prepared in Example 7 below.
[0047] Figure 22 The image shows a modified nano-aluminum sample prepared in Example 8 below.
[0048] Figure 23 The image shows a SEM image of the modified nano-aluminum prepared in Example 8 below.
[0049] Figure 24 Porosity test diagram of the porous geopolymer building material prepared in Example 8 below. Detailed Implementation
[0050] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer.
[0051] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as those skilled in the art. The reagents or raw materials used in this invention are readily available through conventional means, and unless otherwise specified, they are used in accordance with conventional methods or product instructions. Furthermore, any methods and materials similar to or equivalent to those described herein can be applied to the methods of this invention. The technical solution of this invention will now be further described in conjunction with the accompanying drawings and specific embodiments.
[0052] Example 1 A method for preparing porous geopolymer building materials using modified nano-aluminum includes the following steps: (1) The nano-aluminum powder was cleaned with anhydrous ethanol, dried, and then moistened with water to form a moist nano-aluminum with a water content of 5%. This was then placed on a tray in a vacuum radio frequency low-temperature plasma treatment instrument and leveled. The mechanical vacuum pump was then started, and the cavity was evacuated to ≤10 Pa. The process gas inlet mode was then switched, and gas was added according to an Ar:O2 volume ratio of 3:1 until the dynamic working pressure stabilized at 50 Pa. The radio frequency power supply was then turned on and the output power was increased to 100 W to perform plasma treatment on the nano-aluminum powder for 5 minutes. The first 2 minutes were spent using Ar plasma sputtering etching, and the last 3 minutes were spent using O2 plasma oxidation etching. After completion, surface-activated nano-aluminum powder was obtained, which was then removed and transferred to a vacuum-sealed sample bottle for storage.
[0053] (2) According to the mass ratio of chitosan: citric acid: ethanol aqueous solution (mass fraction 80%) = 5g: 10g: 100g, first add the chitosan to the ethanol aqueous solution, and add glacial acetic acid dropwise under stirring to adjust the pH of the system to 4. After stirring, add the citric acid and continue stirring for 20 minutes to obtain the internally modified coating solution.
[0054] (3) The surface-activated nano-aluminum powder is evenly spread on the mesh frame at the bottom of the inner substrate of the supercritical reactor to form a powder layer with a thickness of no more than 1 mm. Then, the internally modified coating liquid is slowly added dropwise to the edge of the powder layer using a pipette, with a ratio of 3 mL: 1 g. After completion, the reactor is sealed, and liquid CO2 is injected into the reactor at a uniform rate until the pressure inside the reactor reaches 10 MPa. After closing the gas inlet valve, the reaction is maintained at temperature and pressure for 30 min. After completion, the product is separated and washed three times with a 50% ethanol aqueous solution. Then, it is vacuum dried at 50 °C for 8 hours to obtain nano-aluminum powder with a citric acid-chitosan internally modified coating layer for later use.
[0055] (4) Add the photoinitiator (2-hydroxy-2-methylphenylacetone) to anhydrous ethanol and stir until homogeneous. The ratio of the two is 0.1 g: 100 mL. Then add nonafluorohexyltrimethoxysilane, and the photoinitiator is 10% of the mass of the nonafluorohexyltrimethoxysilane. Then add glacial acetic acid dropwise to adjust the pH of the system to 4. Stir at room temperature in the dark for 15 min to obtain the externally modified coating solution for later use.
[0056] (5) The nano-aluminum powder with the citric acid-chitosan internal modified coating is placed in a reaction dish and spread into a powder layer with a thickness not exceeding 1 mm. Then, the external modified coating liquid is dropped onto the surface of the powder layer using a pipette, and the ratio of the nano-aluminum powder to the external modified coating liquid is 1 g: 3 mL. Then, ultraviolet irradiation is turned on for 10 min, and the powder is turned over once every 3 min during the process. After completion, the modified nano-aluminum powder is obtained (e.g., Figure 1 , Figure 2 (As shown), for later use.
[0057] (6) Take the following components in the following proportions: 100 parts by weight of fly ash, 40 parts by weight of potassium nepheline, 33 parts by weight of alkali activator, and 1 part by weight of the modified nano-aluminum powder described in this embodiment. Mix the above components with 32 parts by weight of water and stir for 6 minutes to obtain a porous geopolymer building material.
[0058] Performance Testing: 1. The 28-day and 120-day compressive strength of the specimens prepared by the porous geopolymer building material in this embodiment were tested according to the "Test Method for Strength of Cement Mortar (ISO Method)" (GB / T 17671-2021). 2. The specimens prepared by the porous geopolymer building material in this embodiment were heated to 1200℃ at a heating rate of 5℃ / min for 2 hours. After heating, they were cooled to room temperature, and then their compressive strength (referred to as residual strength) was tested according to the "Test Method for Compressive Strength of Refractory Materials at Room Temperature" (GB / T 5072-2023) to measure the fire resistance performance of the porous geopolymer building material. 3. The dry density and porosity (e.g., 28 days) of the specimens prepared by the porous geopolymer building material in this embodiment were tested. Figure 3 (As shown in the figure). The test results for the above performance indicators are shown in Table 1 below.
[0059] Table 1
[0060] Example 2 A method for preparing porous geopolymer building materials using modified nano-aluminum includes the following steps: (1) The nano-aluminum powder was cleaned with anhydrous ethanol, dried, and then moistened with water to form a moist nano-aluminum with a water content of 10%. It was then placed on the tray in the vacuum radio frequency low-temperature plasma treatment instrument and flattened. The mechanical vacuum pump was then started to evacuate the cavity to ≤10Pa, and then the process gas inlet mode was switched. The gas was filled with gas at a volume ratio of Ar:O2 = 2:1 until the dynamic working pressure stabilized at 50Pa. Then the radio frequency power supply was turned on and the output power was increased to 120W to perform plasma treatment on the nano-aluminum powder for 8 minutes, of which: the first 4 minutes were Ar plasma sputtering etching and the last 4 minutes were O2 plasma oxidation etching. After completion, surface-activated nano-aluminum powder was obtained, which was taken out and transferred to a vacuum-sealed sample bottle for storage.
[0061] (2) According to the mass ratio of chitosan: citric acid: ethanol aqueous solution (mass fraction 75%) = 3g: 8g: 70g, first add the chitosan to the ethanol aqueous solution, and add glacial acetic acid dropwise under stirring to adjust the pH of the system to 5. After stirring, add the citric acid and continue stirring for 20 minutes to obtain the internally modified coating solution.
[0062] (3) The surface-activated nano-aluminum powder is evenly spread on the mesh frame at the bottom of the inner substrate of the supercritical reactor to form a powder layer with a thickness of no more than 1 mm. Then, the internally modified coating liquid is slowly added dropwise to the edge of the powder layer using a pipette, with a ratio of 5 mL: 1 g. After completion, the reactor is sealed, and liquid CO2 is injected into the reactor at a uniform rate until the pressure inside the reactor reaches 20 MPa. After closing the gas inlet valve, the reaction is maintained at temperature and pressure for 20 min. After completion, the product is separated and washed three times with a 50% ethanol aqueous solution. Then, it is vacuum dried at 45 °C for 12 hours to obtain nano-aluminum powder with a citric acid-chitosan internally modified coating layer for later use.
[0063] (4) Add the photoinitiator (1-hydroxycyclohexylphenyl ketone) to anhydrous ethanol and stir until homogeneous. The ratio of the two is 0.1 g: 100 mL. Then add nonafluorohexyltrimethoxysilane, and the photoinitiator is 14% of the mass of the nonafluorohexyltrimethoxysilane. Then add glacial acetic acid dropwise to adjust the pH of the system to 5, and stir at room temperature in the dark for 15 min to obtain the externally modified coating solution for later use.
[0064] (5) The nano-aluminum powder with the citric acid-chitosan internal modified coating is placed in a reaction dish and spread into a powder layer with a thickness not exceeding 1 mm. Then, the external modified coating liquid is dropped onto the surface of the powder layer using a pipette, and the ratio of the nano-aluminum powder to the external modified coating liquid is 1 g: 3 mL. Then, ultraviolet irradiation is turned on for 10 min, and the powder is turned over once every 3 min during the process. After completion, the modified nano-aluminum powder is obtained (e.g., Figure 4 , Figure 5 (As shown), for later use.
[0065] (6) Take the following components in the following proportions: 120 parts by weight of metakaolin, 48 parts by weight of potassium nepheline, 40 parts by weight of potassium silicate, and 1.2 parts by weight of the modified nano-aluminum powder described in this embodiment. Mix the above components with 32 parts by weight of water and stir for 6 minutes to obtain a porous geopolymer building material.
[0066] Performance testing: The performance indicators of the porous geopolymer building material prepared in this embodiment were tested using the same method as in Example 1 above (wherein the porosity test diagram is shown in Figure 1). Figure 6 (As shown in the figure), the results are shown in Table 2 below.
[0067] Table 2
[0068] Example 3 A method for preparing porous geopolymer building materials using modified nano-aluminum includes the following steps: (1) The nano-aluminum powder was cleaned with anhydrous ethanol, dried, and then moistened with water to form a moist nano-aluminum with a water content of 15%. This was then placed on a tray in a vacuum radio frequency low-temperature plasma treatment instrument and leveled. The mechanical vacuum pump was then started, and the cavity was evacuated to ≤10 Pa. The process gas inlet mode was then switched, and gas was added according to an Ar:O2 volume ratio of 3:1 until the dynamic working pressure stabilized at 50 Pa. The radio frequency power supply was then turned on and the output power was increased to 150 W to perform plasma treatment on the nano-aluminum powder for 10 min. The first 3 mins were etched using Ar plasma sputtering, and the last 7 mins were etched using O2 plasma oxidation. After completion, surface-activated nano-aluminum powder was obtained, which was then removed and transferred to a vacuum-sealed sample bottle for storage.
[0069] (2) According to the mass ratio of chitosan: citric acid: ethanol aqueous solution (mass fraction 70%) = 2g: 6g: 50g, first add the chitosan to the ethanol aqueous solution, and add citric acid dropwise under stirring to adjust the pH of the system to 4.5. After stirring, add the citric acid and continue stirring for 20 minutes to obtain the internally modified coating solution.
[0070] (3) The surface-activated nano-aluminum powder is evenly spread on the mesh frame at the bottom of the inner substrate of the supercritical reactor to form a powder layer with a thickness of no more than 1 mm. Then, the internally modified coating liquid is slowly added dropwise to the edge of the powder layer using a pipette, with a ratio of 6 mL: 1 g. After completion, the reactor is sealed, and liquid CO2 is injected into the reactor at a uniform rate until the pressure inside the reactor reaches 25 MPa. After closing the gas inlet valve, the reaction is maintained at temperature and pressure for 15 min. After completion, the product is separated and washed three times with a 50% ethanol aqueous solution. Then, it is vacuum dried at 60 °C for 6 hours to obtain nano-aluminum powder with a citric acid-chitosan internally modified coating layer for later use.
[0071] (4) Add the photoinitiator (2-hydroxy-2-methylphenylacetone) to anhydrous ethanol and stir until homogeneous. The ratio of the two is 0.1 g: 100 mL. Then add nonafluorohexyltrimethoxysilane, and the photoinitiator is 20% of the mass of the nonafluorohexyltrimethoxysilane. Then add citric acid dropwise to adjust the pH of the system to 4.5, stir at room temperature in the dark for 15 min to obtain the externally modified coating solution for later use.
[0072] (5) The nano-aluminum powder with the citric acid-chitosan internal modified coating is placed in a reaction dish and spread into a powder layer with a thickness not exceeding 1 mm. Then, the external modified coating liquid is dropped onto the surface of the powder layer using a pipette, and the ratio of the nano-aluminum powder to the external modified coating liquid is 1 g: 3 mL. Then, ultraviolet irradiation is turned on for 15 min, and the powder is turned over once every 3 min during the process. After completion, the modified nano-aluminum powder is obtained (e.g., Figure 7 , Figure 8 (As shown), for later use.
[0073] (6) Take the following components in the following proportions: 60 parts by weight of fly ash, 20 parts by weight of coal gangue powder, 32 parts by weight of potassium nepheline, 27 parts by weight of sodium silicate, and 0.3 parts by weight of the modified nano-aluminum powder described in this embodiment. Mix the above components with 28 parts by weight of water and stir for 6 minutes to obtain a porous geopolymer building material.
[0074] Performance testing: The performance indicators of the porous geopolymer building material prepared in this embodiment were tested using the same method as in Example 1 above (wherein the porosity test diagram is shown in Figure 1). Figure 9 (As shown in the figure), the results are shown in Table 3 below.
[0075] Table 3
[0076] Example 4 A method for preparing porous geopolymer building materials using nano-aluminum includes the following steps: Take the following components in the following proportions: 100 parts by weight of fly ash, 40 parts by weight of potassium nepheline, 33 parts by weight of alkali activator, and 1 part by weight of unmodified nano-aluminum powder (e.g., Figure 10 , Figure 11 (As shown). Mix the above components with 32 parts by weight of water and stir for 6 minutes to obtain a porous geopolymer building material.
[0077] Performance testing: The performance indicators of the porous geopolymer building material prepared in this embodiment were tested using the same method as in Example 1 above (wherein the porosity test diagram is shown in Figure 1). Figure 12 (As shown in the figure), the results are shown in Table 4 below.
[0078] Table 4
[0079] Example 5 A method for preparing porous geopolymer building materials using modified nano-aluminum includes the following steps: Take the following components in the following proportions: 100 parts by weight of fly ash, 40 parts by weight of potassium nepheline, 33 parts by weight of alkali activator, and 1 part by weight of the nano-aluminum powder with citric acid-chitosan internal modified coating prepared in step (3) of Example 1 above (e.g. Figure 13 , Figure 14 (As shown). Mix the above components with 32 parts by weight of water and stir for 6 minutes to obtain a porous geopolymer building material.
[0080] Performance testing: The performance indicators of the porous geopolymer building material prepared in this embodiment were tested using the same method as in Example 1 above (wherein the porosity test diagram is shown in Figure 1). Figure 15 (As shown in the figure), the results are shown in Table 5 below.
[0081] Table 5
[0082] Example 6 A method for preparing porous geopolymer building materials using modified nano-aluminum is the same as in Example 2 above, except that the modified nano-aluminum powder in this example is prepared using the following steps: (1) The nano-aluminum powder was cleaned with anhydrous ethanol, dried, and then moistened with water to form a moist nano-aluminum with a water content of 10%. It was then placed on the tray in the vacuum radio frequency low-temperature plasma treatment instrument and flattened. The mechanical vacuum pump was then started to evacuate the cavity to ≤10Pa, and then the process gas inlet mode was switched. The gas was filled with gas at a volume ratio of Ar:O2 = 2:1 until the dynamic working pressure stabilized at 50Pa. Then the radio frequency power supply was turned on and the output power was increased to 120W to perform plasma treatment on the nano-aluminum powder for 8 minutes, of which: the first 4 minutes were Ar plasma sputtering etching and the last 4 minutes were O2 plasma oxidation etching. After completion, surface-activated nano-aluminum powder was obtained, which was taken out and transferred to a vacuum-sealed sample bottle for storage.
[0083] (2) Add the photoinitiator (1-hydroxycyclohexylphenyl ketone) to anhydrous ethanol and stir until homogeneous. The ratio of the two is 0.1 g: 100 mL. Then add nonafluorohexyltrimethoxysilane, and the photoinitiator is 14% of the mass of the nonafluorohexyltrimethoxysilane. Then add glacial acetic acid dropwise to adjust the pH of the system to 5, and stir at room temperature in the dark for 15 min to obtain the externally modified coating solution for later use.
[0084] (3) The surface-activated nano-aluminum powder of this embodiment is placed in a reaction dish and spread into a powder layer with a thickness not exceeding 1 mm. Then, the external modification coating liquid is dropped onto the surface of the powder layer using a pipette, and the ratio of the surface-activated nano-aluminum powder to the external modification coating liquid is 1 g: 3 mL. Then, ultraviolet irradiation is turned on for 10 min, and the powder is turned over once every 3 min during the process. After completion, modified nano-aluminum powder is obtained (e.g., Figure 16 , Figure 17 (As shown).
[0085] Performance testing: The performance indicators of the porous geopolymer building material prepared in this embodiment were tested using the same method as in Example 1 above (wherein the porosity test diagram is shown in Figure 1). Figure 18 (As shown in the figure), the results are shown in Table 6 below.
[0086] Table 6
[0087] Example 7 A method for preparing porous geopolymer building materials using modified nano-aluminum is the same as in Example 3 above, except that the modified nano-aluminum powder in this example is prepared using the following steps: (1) Chitosan was added to the ethanol aqueous solution at a mass ratio of 6g:50g, and citric acid was added dropwise under stirring to adjust the pH of the system to 4.5. After stirring, the citric acid was added again and stirring was continued for 20 minutes to obtain the internally modified coating solution.
[0088] (2) The surface-activated nano-aluminum powder prepared in Example 3 was evenly spread on the mesh frame at the bottom of the inner substrate of the supercritical reactor to form a powder layer with a thickness of no more than 1 mm. Then, the internally modified coating liquid was slowly added dropwise to the edge of the powder layer using a pipette, with a ratio of 6 mL: 1 g. After completion, the reactor was sealed, and liquid CO2 was injected into the reactor at a uniform rate until the pressure inside the reactor reached 25 MPa. After closing the gas inlet valve, the reaction was maintained at temperature and pressure for 15 min. After completion, the product was separated and washed three times with a 50% ethanol aqueous solution. Then, it was vacuum dried at 60 °C for 6 hours to obtain nano-aluminum powder with a citric acid-chitosan internally modified coating layer for later use.
[0089] (3) Add the photoinitiator (2-hydroxy-2-methylphenylacetone) to anhydrous ethanol and stir until homogeneous. The ratio of the two is 0.1 g: 100 mL. Then add nonafluorohexyltrimethoxysilane, and the photoinitiator is 20% of the mass of the nonafluorohexyltrimethoxysilane. Then add citric acid dropwise to adjust the pH of the system to 4.5, stir at room temperature in the dark for 15 min to obtain the externally modified coating solution for later use.
[0090] (4) The nano-aluminum powder with the citric acid-chitosan internal modified coating is placed in a reaction dish and spread into a powder layer with a thickness not exceeding 1 mm. Then, the external modified coating liquid is dropped onto the surface of the powder layer using a pipette, and the ratio of the nano-aluminum powder to the external modified coating liquid is 1 g: 3 mL. Then, ultraviolet irradiation is turned on for 15 min, and the powder is turned over once every 3 min during the process. After completion, the modified nano-aluminum powder is obtained (e.g., Figure 19 , Figure 20 (As shown).
[0091] Performance testing: The performance indicators of the porous geopolymer building material prepared in this embodiment were tested using the same method as in Example 1 above (wherein the porosity test diagram is shown in Figure 1). Figure 21 (As shown in the figure), the results are shown in Table 7 below.
[0092] Table 7
[0093] Example 8 A method for preparing porous geopolymer building materials using modified nano-aluminum is the same as in Example 2 above, except that the modified nano-aluminum powder in this example is prepared using the following steps: (1) The surface-activated nano-aluminum powder prepared in Example 2 above was placed in a beaker, and then the internal modification coating solution of Example 2 above was added dropwise to it, with a ratio of 5 mL: 1 g. The beaker was then sealed and magnetically stirred for 30 min. After the reaction was completed, the product was separated and washed three times with a 50% ethanol aqueous solution, and then vacuum dried at 45 °C for 12 hours to obtain nano-aluminum powder with a citric acid-chitosan internal modification coating layer for later use.
[0094] (2) Add the photoinitiator (1-hydroxycyclohexylphenyl ketone) to anhydrous ethanol and stir until homogeneous. The ratio of the two is 0.1 g: 100 mL. Then add nonafluorohexyltrimethoxysilane, and the photoinitiator is 14% of the mass of the nonafluorohexyltrimethoxysilane. Then add glacial acetic acid dropwise to adjust the pH of the system to 5, and stir at room temperature in the dark for 15 min to obtain the externally modified coating solution for later use.
[0095] (3) The nano-aluminum powder with the citric acid-chitosan internal modified coating is placed in a reaction dish and spread into a powder layer with a thickness not exceeding 1 mm. Then, the external modified coating liquid is dropped onto the surface of the powder layer using a pipette, and the ratio of the nano-aluminum powder to the external modified coating liquid is 1 g: 3 mL. Then, ultraviolet irradiation is turned on for 10 min, and the powder is turned over once every 3 min during the process. After completion, the modified nano-aluminum powder is obtained (e.g., Figure 22 , Figure 23 (As shown).
[0096] Performance testing: The performance indicators of the porous geopolymer building material prepared in this embodiment were tested using the same method as in Example 1 above (wherein the porosity test diagram is shown in Figure 1). Figure 24 (As shown in the figure), the results are shown in Table 8 below.
[0097] Table 8
[0098] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A multi-level barrier slow-release nano-aluminum-based porous geopolymer building material, characterized in that, The composition includes the following components in the following proportions: 80-120 parts by weight of solid waste-based cementitious material, 32-48 parts by weight of potassium nepheline, 27-40 parts by weight of alkali activator, and 0.3-1.2 parts by weight of modified nano-aluminum powder; wherein: The modified nano-aluminum powder includes a nano-aluminum core, and the surface of the core has a citric acid-chitosan internal modified coating layer formed by citric acid chelating with the aluminum ions provided by the core through its carboxyl groups and chitosan molecular chains crosslinking with the citric acid through hydrogen bonds. It also has an outer modified coating layer formed by the dehydration condensation of silanol groups formed by the hydrolysis of nonafluorohexyltrimethoxysilane and the hydroxyl and amino groups in the inner modified coating layer.
2. The multi-level barrier slow-release nano-aluminum-based porous geopolymer building material according to claim 1, characterized in that, The solid waste-based cementitious material includes at least one of the following: fly ash, metakaolin, coal gangue powder, and mineral powder.
3. The multi-level barrier slow-release nano-aluminum-based porous geopolymer building material according to claim 1, characterized in that, The alkaline activator includes at least one of potassium silicate and sodium silicate.
4. The multi-level barrier slow-release nano-aluminum-based porous geopolymer building material according to any one of claims 1-3, characterized in that, The modified nano-aluminum powder was prepared using the following method: (1) Plasma treatment is performed on the surface-wetted nano-aluminum powder to obtain surface-activated nano-aluminum powder for later use; (2) Prepare an ethanol aqueous solution containing chitosan and citric acid as an internal modification coating solution, mix it with the surface-activated nano-aluminum powder and react it in a supercritical CO2 environment. After completion, wash and dry the product to obtain nano-aluminum powder with a citric acid-chitosan internal modification coating layer for later use. (3) Add a photoinitiator, an acidic external modification coating solution formed by nonafluorohexyltrimethoxysilane and anhydrous ethanol to the nano-aluminum powder with citric acid-chitosan internal modification coating layer, and then perform photo-treatment to obtain the modified nano-aluminum powder.
5. The multi-level barrier slow-release nano-aluminum-based porous geopolymer building material according to claim 4, characterized in that, In step (1), the moisture content of the surface-wetted nano-aluminum powder is 5~15 wt.%; Alternatively, in step (1), the gas source for plasma treatment is a mixture of argon and oxygen in a volume ratio of 2 to 3:
1. Alternatively, in step (1), the power of the ion treatment is 100~150W and the time is 5~10min; Alternatively, in step (2), the mass fraction of the ethanol aqueous solution is 70-80%.
6. The multi-level barrier slow-release nano-aluminum-based porous geopolymer building material according to claim 4, characterized in that, In step (2), the mass ratio of chitosan, citric acid, and ethanol aqueous solution is 2~5g:6~10g:50~100g.
7. The multi-level barrier slow-release nano-aluminum-based porous geopolymer building material according to claim 4, characterized in that, In step (2), the internally modified coating solution is prepared by the following method: chitosan is added to an ethanol aqueous solution, the pH of the system is adjusted to 4-5, and then citric acid is added and stirred until fully dissolved to obtain the internally modified coating solution.
8. The multi-level barrier slow-release nano-aluminum-based porous geopolymer building material according to claim 4, characterized in that, In step (2), the ratio of the surface-activated nano-aluminum powder to the internally modified coating solution is 1g:3~6mL; Alternatively, in step (2), the reaction time is 15-30 min and the pressure is 10-25 MPa; Alternatively, in step (2), the drying temperature is 45~60℃ and the time is 6~12 hours; Alternatively, in step (3), the photoinitiator includes at least one of 2-hydroxy-2-methylphenylacetone, 1-hydroxycyclohexylphenyl ketone, and 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone.
9. The multi-level barrier slow-release nano-aluminum-based porous geopolymer building material according to claim 4, characterized in that, In step (3), the ratio of the nano-aluminum powder to the externally modified coating liquid is 1~3g:10mL.
10. The multi-level barrier slow-release nano-aluminum-based porous geopolymer building material according to claim 4, characterized in that, In step (3), the photoinitiator is 10-20% by mass of nonafluorohexyltrimethoxysilane; Alternatively, in step (3), the acidity is pH 4 to 5; Alternatively, in step (3), the illumination treatment time is 10-15 minutes.