Geopolymer porous spherical material as well as preparation method and application thereof

Abstract

The invention discloses a geopolymer porous spherical material and a preparation method and application thereof, and belongs to the technical field of porous materials. The preparation method comprises the following steps: mixing tailings and fly ash according to a mass ratio of 1: (1-5), and carrying out uniform ball milling to obtain mixed powder; then uniformly mixing the mixed powder with micro-nano bubble water containing an alkali activator, mixing the obtained geopolymer slurry with a hydrogen peroxide solution and the micro-nano bubble water, and stirring and foaming to obtain foamed slurry; and dropwise adding the foaming slurry into dimethyl silicone oil to form microspheres, curing and molding the microspheres, taking out, drying, washing, drying and curing, and calcining the cured microspheres to obtain the geopolymer porous spherical material. The preparation method is simple in process, non-toxic, environment-friendly and suitable for popularization and application, the prepared geopolymer porous spherical material has considerable adsorption capacity on toluene, is resistant to high temperature and can be recycled, and a large amount of solid waste is taken as a raw material, so that the cost is reduced.

Description

Technical Field

[0001] This invention belongs to the field of porous materials technology, specifically relating to a geopolymer porous spherical material, its preparation method and application, and particularly to the application of the geopolymer porous spherical material in the adsorption of toluene. Background Technology

[0002] Volatile organic pollutants (VOCs) pose a serious threat to global ecosystems and human health. Some VOCs are carcinogenic, and exposure to VOCs can lead to acute and chronic diseases. Toluene, as a typical VOC, is highly toxic and volatile, posing a serious threat to the ecological environment and human health; therefore, its efficient treatment is crucial. With increasingly stringent emission standards in my country, developing efficient materials and technologies for toluene removal has become essential.

[0003] Currently, commonly used methods for toluene treatment in my country include adsorption, condensation, biological methods, photocatalytic oxidation, combustion, and membrane separation. Each method has its own characteristics and advantages. Among them, adsorption has received widespread attention due to its unique ease of operation. In this process, adsorbent materials with high specific surface area structures or special functional groups can be used to reduce pollutants, thereby lowering the toluene concentration. Adsorption treatment of toluene has been used for a long time. Its advantages include simple operation, low energy consumption, low investment costs, high efficiency, and no secondary pollution. Therefore, it has a promising application prospect in toluene treatment.

[0004] Commonly used adsorbents mainly include: 1) Carbon-based adsorbents: Carbon-based adsorption refers to the adsorption of toluene using solid carbon materials such as activated carbon, activated carbon fiber, biochar, graphene, and carbon nanotubes as adsorbents. It is a physical adsorption method. However, its main drawbacks during adsorption include high carbon loss, poor thermal stability, and flammability and explosiveness. 2) Molecular sieves: These are an important class of inorganic microporous materials. Due to the presence of Al in the molecular sieve framework... 3+The presence of ions gives it a negative charge. To maintain electroneutrality, cations that compensate for the charge must exist in the voids of the framework. These cations act as adsorption sites and have an affinity for polar molecules. However, it should be noted that for good adsorption, the pore size should be designed to be larger than the size of the adsorbate molecules. When selecting molecular sieves for different target pollutants, the physicochemical properties of the pollutants, the structural type of the molecular sieve, the silica-to-alumina ratio, and the hydrophobic properties must be fully considered. 3) Organic polymer materials: Metal-organic frameworks (MOFs) are porous structures composed of metal ions and organic linkers. Due to their large specific surface area, numerous active sites, high and adjustable porosity, they exhibit excellent adsorption characteristics for different VOCs. Their adsorption capacity for VOCs can reach 240-1375 mg / g, which is higher than that of common carbon-based adsorbents. However, MOFs have poor water stability, and the effect of humidity should be carefully considered in their practical applications. Water vapor not only destroys the MOF framework structure, reduces its specific surface area, and shrinks the pore size and volume, but also competes with the adsorbate for adsorption, causing a sharp decrease in the adsorption capacity of the MOF. 4) Metal oxides: Activated alumina (γ-Al₂O₃) is a porous material often used as an adsorbent for VOCs removal. The loading order of Ag and Mn affects the adsorption performance. Loading Mn first and then Ag results in a large amount of Ag on the surface of γ-Al₂O₃. + Ag + New active sites for adsorption are beneficial for toluene adsorption. However, using precious metals as load materials is not very economical and can produce toxic substances, which can also affect their load-bearing performance.

[0005] Therefore, there is a need to prepare an adsorbent with considerable toluene adsorption capacity, adjustable pore size, and low cost. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention proposes a geopolymer porous spherical material, its preparation method, and its applications. This geopolymer porous spherical material exhibits considerable adsorption capacity for toluene, is heat-resistant, and utilizes bulk solid waste as raw material, turning waste into treasure and reducing costs. Furthermore, the preparation method of this invention is simple, non-toxic, and environmentally friendly, making it suitable for widespread application.

[0007] To achieve the above objectives, the present invention provides the following technical solution: One of the technical solutions of the present invention is a method for preparing a porous spherical geopolymer material, comprising the following steps: 1) After mixing tailings and fly ash at a mass ratio of 1:1-5, the mixture is ball-milled until homogeneous to obtain a mixed powder; 2) Mix the mixed powder with micro-nano bubble water containing alkali activator to obtain a geopolymer slurry; 3) Mix hydrogen peroxide solution, micro-nano bubble water and geopolymer slurry, stir and foam to obtain foamed slurry; 4) Add the foaming slurry to dimethyl silicone oil to form microspheres. After the microspheres have solidified and shaped, remove them, dry them, wash them, and then dry and cure them to obtain cured microspheres. 5) The cured microspheres are calcined to obtain porous spherical materials of geopolymer.

[0008] Preferably, in step 1), the mass ratio of tailings to fly ash is 1:1.8-3.5; more preferably, the mass ratio of tailings to fly ash is 1:1.9-2.2; and particularly preferably, the mass ratio of tailings to fly ash is 1:2.

[0009] Preferably, in step 1), the ball-to-material ratio of the ball mill is 2-2.5:1, the rotation speed is 400-450 rpm, and the time is 1-4 h; more preferably, it is 2-3 h.

[0010] Preferably, in step 2), the alkaline activator is a mixture of sodium silicate and sodium hydroxide, and the mass ratio of the mixed powder, sodium silicate, and sodium hydroxide is 30:5:1.132-1.18.

[0011] Preferably, in step 2), the modulus of the micro-nano bubble water containing the alkali activator is 1.2-1.4; more preferably, the modulus of the micro-nano bubble water containing the alkali activator is 1.2.

[0012] Preferably, in step 2), the micro-nano bubble water containing the alkali activator also contains sodium dodecyl sulfate, and the amount of sodium dodecyl sulfate added is 2-4 wt% of the mass of the mixed powder; more preferably, the amount of sodium dodecyl sulfate added is 3 wt% of the mass of the mixed powder.

[0013] Preferably, in step 2), the preparation method of the micro-nano bubble water containing the alkali activator is as follows: sodium silicate powder, sodium hydroxide and micro-nano bubble water are mixed and stirred at 60-70°C until completely dissolved, then sodium dodecyl sulfate is added, stirred and mixed evenly, and cooled to room temperature to obtain micro-nano bubble water containing the alkali activator.

[0014] Preferably, in step 2), the method of mixing evenly is stirring, with a stirring speed of 450-500 rpm and a stirring time of 15-20 min.

[0015] Preferably, in steps 2) and 3), the micro-nano bubble water is prepared using a micro-nano bubble generator with the following parameters: gas flow rate 450-500 mL / min, water flow rate 500-550 L / min, mixing rate 300-350 L / min, and a total treatment time of 1 h based on a water volume of 1 L.

[0016] Preferably, in step 3), the concentration of the hydrogen peroxide solution is 30 wt%.

[0017] Preferably, in step 3), the hydrogen peroxide solution and the micro-nano bubble water are mixed at a volume ratio of 0.5-1.5:1; more preferably, the ratio is 1:1.

[0018] Preferably, in step 3), the water-to-solid ratio of the foaming slurry is 0.5-0.6, and the solid mass of the water-to-solid ratio is based on the mass of the mixed powder; more preferably, it is 0.55.

[0019] Preferably, in step 3), the solid content of the foaming slurry is 62-66 wt%; more preferably, it is 64 wt%.

[0020] Preferably, in step 3), the stirring and foaming time is 20-30 seconds.

[0021] Preferably, in step 4), the temperature of the dimethyl silicone oil is 70-80°C.

[0022] Preferably, in step 4), the curing time of the microspheres is 15-20 minutes.

[0023] Preferably, in step 4), the product is dried in a forced-air drying oven for 30-60 minutes, washed twice each with anhydrous ethanol and micro-nano bubble water, and then placed in a forced-air drying oven for 10-12 hours for curing.

[0024] Preferably, in step 5), the calcination temperature is 500°C and the calcination time is 3-5 hours; more preferably, it is 3 hours.

[0025] The second technical solution of the present invention is a geopolymer porous spherical material prepared by the preparation method.

[0026] Preferably, the Si / Al molar ratio of the geopolymer porous spherical material is 1.45.

[0027] The third technical solution of the present invention is the application of the geopolymer porous spherical material in the adsorption of toluene.

[0028] Compared with the prior art, the technical effects of the present invention are as follows: (1) The geopolymer porous spherical material of the present invention has abundant porosity, increased active sites, and improved toluene adsorption capacity.

[0029] (2) The geopolymer porous spherical material of the present invention enhances the toluene adsorption capacity by matching the specific surface area with the pore size, thereby making resource utilization of tailings and fly ash, realizing waste treatment, and achieving the strategic goal of green economic sustainable development.

[0030] (3) The raw materials used in this invention come from bulk solid waste. By making solid waste resources and turning waste into treasure, not only is the land occupied reduced, but the pollution caused to the ecological environment is also alleviated. At the same time, it can also create considerable economic benefits.

[0031] (4) Compared with traditional adsorbents, the geopolymer porous spherical material of the present invention has the characteristics of high temperature resistance. The adsorption effect of traditional adsorbents usually weakens under high temperature conditions, the pore structure may change, or even fail. However, the geopolymer porous spherical material of the present invention desorbs toluene after heating and is regenerated, which has little impact on the adsorption capacity of toluene, thus achieving the purpose of recycling.

[0032] (5) In particular, when tailings and fly ash are used in a mass ratio of 1:2, the synthesized geopolymer porous spherical material has a silicon-aluminum ratio of 1.45, which not only has the largest specific surface area but also the highest mechanical strength.

[0033] (6) The preparation method of the geopolymer porous spherical material of the present invention involves a simple process, is non-toxic and environmentally friendly, and is suitable for promotion and application. Attached Figure Description

[0034] Figure 1 This is a process flow diagram of the preparation method of the geopolymer porous spherical material of the present invention.

[0035] Figure 2 This is a SEM image of the geopolymer porous spherical material of Example 1 of the present invention; In this image, a is a 50x magnification image, b is a 100x magnification image, and c is a 200x magnification image.

[0036] Figure 3 The images shown are SEM images of the geopolymer porous spherical materials of Example 1 and Comparative Example 1 of the present invention, where a is the SEM image of the geopolymer porous spherical material of Example 1 and b is the SEM image of the geopolymer porous spherical material of Comparative Example 1.

[0037] Figure 4 The XRD patterns of the geopolymer porous spherical materials of Examples 1 (Si / Al molar ratio = 1.45), 2 (Si / Al molar ratio = 1.3), 3 (Si / Al molar ratio = 1.35), 4 (Si / Al molar ratio = 1.4), and 5 (Si / Al molar ratio = 1.5) of this invention are shown; Ts in the figure represents tailings.

[0038] Figure 5The images show the FT-IR spectra of the geopolymer porous spherical materials of Examples 1 (Si / Al molar ratio = 1.45), 2 (Si / Al molar ratio = 1.3), 3 (Si / Al molar ratio = 1.35), 4 (Si / Al molar ratio = 1.4), and 5 (Si / Al molar ratio = 1.5) of this invention; FA in the figures represents fly ash.

[0039] Figure 6 This is a schematic diagram of the method for testing the adsorption performance of toluene on five samples in Examples 1-5 of the present invention. Detailed Implementation

[0040] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0041] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0042] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0043] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0044] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0045] like Figure 1 As shown, the method for preparing the geopolymer porous spherical material of the present invention includes the following steps: 1) After mixing tailings and fly ash at a mass ratio of 1:1-5, the mixture is ball-milled until homogeneous to obtain a mixed powder; 2) Mix the mixed powder with micro-nano bubble water containing alkali activator to obtain a geopolymer slurry; 3) Mix hydrogen peroxide solution, micro-nano bubble water and geopolymer slurry, stir and foam to obtain foamed slurry; 4) Add the foaming slurry to dimethyl silicone oil to form microspheres. After the microspheres have solidified and shaped, remove them, dry them, wash them, and then dry and cure them to obtain cured microspheres. 5) The cured microspheres are calcined to obtain porous spherical materials of geopolymer.

[0046] In this invention, by adding tailings of different mass fractions to fly ash, the silica-alumina ratio of the final product can be adjusted. Preferably, the mass ratio of tailings to fly ash is 1:1.8-3.5, more preferably 1:1.9-2.2, and particularly preferably 1:2. In some embodiments, ratios of 1:1.7, 1:1.8, 1:1.9, 1:2, 1:2.1, 1:2.2, 1:2.3, 1:2.4, and 1:2.5 are used. It is particularly noteworthy that when the mass ratio of tailings to fly ash is 1:2, the prepared material possesses unique structural properties and achieves unexpected technical effects in toluene adsorption.

[0047] In this invention, the preferred ball-to-powder ratio is 2-2.5:1, the rotation speed is 400-450 rpm, and the time is 1-4 hours, more preferably 2-3 hours. A ball mill is typically used for ball milling. Ball milling can obtain a uniform mixed powder.

[0048] In this invention, micro / nano bubble water is prepared using a micro / nano bubble generator with the following parameters: gas flow rate 450-500 mL / min, water flow rate 500-550 L / min, mixing rate 300-350 L / min, and a total treatment time of 1 h (based on a water volume of 1 L). Micro / nano bubbles effectively improve the uniformity of geopolymer slurries, enhance the dispersion of bubbles within the slurry, and yield a well-dispersed foamed slurry, thereby optimizing its pore structure.

[0049] In this invention, the preferred alkali activator is a mixture of sodium silicate and sodium hydroxide, with a mass ratio of mixed powder, sodium silicate, and sodium hydroxide of 30:5:(1.132-1.18). The modulus of the micro / nano bubble water containing the alkali activator is 1.2-1.4, more preferably 1.2 (the modulus is controlled by the sodium hydroxide content). Preferably, the micro / nano bubble water containing the alkali activator also contains sodium dodecyl sulfate, with the amount of sodium dodecyl sulfate added being 2-4 wt% of the mass of the mixed powder, more preferably 3 wt%.

[0050] In this invention, the preparation method of micro-nano bubble water containing alkali activator is as follows: sodium silicate powder, sodium hydroxide and micro-nano bubble water are mixed and stirred at 60-70℃ until completely dissolved (usually 30 min), then sodium dodecyl sulfate is added, stirred and mixed evenly, and cooled to room temperature to obtain micro-nano bubble water containing alkali activator.

[0051] In this invention, the method for uniformly mixing the powder with micro-nano bubble water containing an alkaline activator is stirring, with a stirring speed of 450-500 rpm and a stirring time of 15-20 min.

[0052] In this invention, the concentration of hydrogen peroxide solution is 30 wt%. The hydrogen peroxide solution and micro / nano bubble water are mixed at a volume ratio of 0.5-1.5:1, preferably 1:1, and the foaming time is 20-30 seconds. Preferably, the hydrogen peroxide solution is first mixed with the micro / nano bubble water, and the resulting mixture is then mixed with the geopolymer slurry. The water-to-solid ratio of the foaming slurry is preferably 0.5-0.6, such as in some embodiments 0.5, 0.51, 0.52, 0.53, 0.54, 0.55, 0.56, 0.57, 0.58, 0.59, or 0.6, where the solid mass of the water-to-solid ratio is based on the mass of the mixed powder. The solid content of the foaming slurry is preferably 62 wt%-66 wt%, more preferably 64 wt%.

[0053] In this invention, the temperature of the dimethyl silicone oil is 70-80℃. The foaming slurry is added dropwise to the dimethyl silicone oil using a disposable syringe. Utilizing the principle of oil-water immiscibility, it solidifies into microspheres under the influence of temperature, with a curing time typically of 15-20 minutes. After drying in a forced-air drying oven for 30-60 minutes, the microspheres are washed twice each with anhydrous ethanol and micro-nano bubble water using a circulating water vacuum pump and a Buchner funnel, and then placed back into the forced-air drying oven for curing for 10-12 hours.

[0054] In this invention, calcination can remove bound water from the material structure and promote further cross-linking and densification of the geopolymer network. Calcination is usually carried out in a muffle furnace at a temperature of 500°C for 3-5 hours. If the calcination time is too long, the pores will collapse, so 3 hours is preferred.

[0055] This invention also provides a geopolymer porous spherical material prepared by the above-described method, wherein the Si / Al molar ratio of the geopolymer porous spherical material is 1.35-1.5. This geopolymer porous spherical material, while ensuring considerable adsorption capacity, is resistant to high temperatures and can be recycled through subsequent desorption and regeneration at elevated temperatures. Preferably, the Si / Al molar ratio is 1.45, exhibiting unexpected and optimal technical effects.

[0056] This invention also provides the application of the above-mentioned geopolymer porous spherical material in the adsorption of toluene. It is applicable to the fields of industrial exhaust gas purification and resource utilization, realizing "waste treatment with waste".

[0057] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to embodiments.

[0058] In the following embodiments, various processes and methods not described in detail are conventional methods known in the art. Unless otherwise specified, the materials, reagents, apparatus, instruments, equipment, etc., used in the following embodiments are commercially available. The tailings in the embodiments are derived from tailings ponds.

[0059] In this embodiment of the invention, room temperature refers to 25±2℃.

[0060] Example 1 1) Preparation of micro-nano bubble water: Add 1L of deionized water to a 2L beaker, ensuring the water level covers the inlet and outlet pipes. Adjust the three parameters of the micro-nano bubble generator (which draws air from the outside via a pressure pump) to their respective ranges (mixing rate: 300-350L / min, gas flow rate: 450-500mL / min, water flow rate: 500-550L / min). After 1 hour, micro-nano bubble water is obtained.

[0061] 2) Raw material pretreatment: 10g of tailings and 20g of fly ash were placed in a ball mill with a ball-to-material ratio of 2.5:1. The mixture was ball-milled for 1 hour at a speed of 450 rpm and the mixed powder was collected.

[0062] 3) Preparation of geopolymer slurry: Weigh 5g Na2SiO3 and 1.132g NaOH and add them to 14.8mL of micro-nano bubble water. Stir at 60℃ until completely dissolved, then add 0.9g sodium dodecyl sulfate and stir to mix evenly. Cool to room temperature, add 30g of mixed powder, and stir at 500rpm for 20min to obtain geopolymer slurry.

[0063] 4) Preparation of foaming slurry: Mix 1 mL of hydrogen peroxide solution (30 wt%), 1 mL of micro-nano bubble water and geopolymer slurry, stir for 30 s to obtain foaming slurry with a water-to-solid ratio of 0.55.

[0064] 5) Preparation of porous spherical materials: A 50 mL disposable syringe was used to transfer the foaming slurry dropwise into dimethyl silicone oil at 80℃. Utilizing the principle of water-oil immiscibility, the slurry solidified into microspheres under temperature. After 20 minutes, the microspheres were collected using a strainer and dried in a forced-air drying oven for 30 minutes. They were then washed twice each with anhydrous ethanol and micro / nano bubble water, and cured by forced-air drying for 12 hours. Finally, they were calcined in a muffle furnace at 500℃ for 3 hours to obtain porous spherical geopolymer materials. SEM images are shown below. Figure 2 As shown.

[0065] Example 2 Steps 1)-5) are the same as in Example 1, except that in step 2), 10g of tailings and 20g of fly ash are replaced with 5g of tailings and 25g of fly ash.

[0066] Example 3 Steps 1)-5) are the same as in Example 1, except that in step 2), 10g of tailings and 20g of fly ash are replaced with 7g of tailings and 23g of fly ash.

[0067] Example 4 Steps 1)-5) are the same as in Example 1, except that in step 2), 10g of tailings and 20g of fly ash are replaced with 9g of tailings and 21g of fly ash.

[0068] Example 5 Steps 1)-5) are the same as in Example 1, except that in step 2), 10g of tailings and 20g of fly ash are replaced with 12g of tailings and 18g of fly ash.

[0069] Comparative Example 1 Steps 1)-5) are the same as in Example 1, except that the micro-nano bubble water is replaced with deionized water.

[0070] The toluene adsorption performance of the five samples in Examples 1-5 above was tested. Figure 6As shown, gaseous toluene stored in a toluene cylinder is depressurized by a pressure reducing valve and then sent to the mixing cylinder. Similarly, N2 stored in an N2 cylinder is depressurized by a pressure reducing valve and also sent to the mixing cylinder. The amounts of gaseous toluene and N2 sent to the mixing cylinder are controlled by mass flow meters and displayed on a flow meter. The gaseous toluene and N2 mix in the mixing cylinder, which is equipped with a heating jacket to maintain the temperature at 80°C to prevent toluene condensation. First, a VOCs detector is used to directly detect the mixed gas (bypass). Once the toluene concentration gradually approaches a constant value, the mixed gas is first passed into a container filled with a sample (adsorbent), and then detected again by the VOCs detector (main path). Some of the toluene will be adsorbed by the sample (adsorbent), causing the VOCs detector reading to decrease. Data is recorded periodically, and the toluene adsorption capacity is calculated using the recorded data. It should be noted that all pipelines are equipped with heating tape to prevent toluene condensation.

[0071] The operating conditions were as follows: test mode was toluene, initial toluene concentration was 90 ppm, mixed gas velocity was 500 mL / min, sample volume was 1 g, adsorption time was 30 min, and temperature was room temperature. The experimental results are shown in Table 1.

[0072] Table 1. Toluene adsorption capacity of samples in Examples 1-5

[0073] Comparing Examples 1-5 in Table 1, it can be seen that Example 1 exhibits the highest toluene adsorption capacity, reaching 11 mg / g, which is approximately twice that of Example 4, demonstrating a significant technological improvement. It can also be seen that as the silicon-to-aluminum ratio increases from 1.3 to 1.4, the toluene adsorption capacity gradually increases; however, when the silicon-to-aluminum ratio is 1.5, the toluene adsorption capacity actually decreases to its lowest value.

[0074] The samples from Examples 1-5 above were subjected to specific surface area (BET) characterization tests (determination of specific surface area of ​​solid materials by gas adsorption BET method GB / T 19587-2017) and mechanical strength characterization tests (determination of mechanical strength by compression test method for plastics GB / T1041-2008). The operating conditions were: nitrogen as the adsorbed gas, degassing temperature of 100℃, and degassing time of 12h. The results are shown in Table 2.

[0075] Table 2. Specific surface area and mechanical strength of samples in Examples 1-5

[0076] As shown in Table 2, as the silica-alumina ratio of the aluminosilicate raw material increases from 1.3 to 1.4, the specific surface area and mechanical strength of the prepared porous spherical materials gradually increase. Example 1, with a silica-alumina ratio of 1.45, has the largest specific surface area and the smallest mechanical strength. However, when the silica-alumina ratio of the raw material reaches 1.5, although the mechanical strength is increased by 52% compared to Example 4, the specific surface area is sacrificed. It can be seen that for porous spherical materials, abundant porosity and excellent mechanical strength cannot be achieved at the same time. Beyond a certain range, they are even contradictory. For toluene adsorbent materials, specific surface area is crucial for adsorption performance.

[0077] exist Figure 4 Observations revealed that the amount of tailings used had little effect on the crystalline structure of the porous geopolymer; the morphology and trends of the diffraction patterns of the five samples showed minimal changes, and all prepared materials exhibited an amorphous structure. Peaks characteristic of the aluminosilicate gel phase were observed around 2θ = 10°–40°, indicating that the prepared material is an amorphous geopolymer. Furthermore, compared to the raw material tailings, the porous geopolymer material showed a significant increase in the number and types of diffraction peaks, further confirming the occurrence of the geopolymerization reaction.

[0078] exist Figure 5 The study found that the five samples and the raw material fly ash showed roughly the same trend, with essentially identical scanning spectra. This indicates that changes in the amount of fly ash do not alter the types of reaction products. However, absorption peaks at certain wavenumbers shifted, and the peak shapes also changed significantly. Comparison with standard spectra revealed that... Figure 5 The wavenumber in the mid-low frequency range is 466.18 cm⁻¹. -1 The absorption peak at [0.05] is caused by the bending vibration of the Si-O bond in [SiO4], with a wavenumber of 561.76 cm⁻¹. -1 The peaks on the left and right are stretching vibrations caused by the Al-O bonds in [AlO4], which are closely related to the presence of mullite in the raw material fly ash. In the mid-frequency region, the strongest and broadest absorption peak corresponds to a wavenumber of 1033.86 cm⁻¹. -1 This represents the stretching vibrations of Si-O-Si and Si-O-Al bonds, and this peak originates from the amorphous aluminosilicate glass in the raw material fly ash. The wavenumber in the high-frequency region is 3445.81 cm⁻¹. -1 The absorption peak at that point originates from the stretching vibration of the hydroxyl group (-OH) in the water molecule.

[0079] Figure 3 These are SEM images of the geopolymer porous spherical materials of Example 1 and Comparative Example 1 of the present invention, wherein a is the SEM image of the geopolymer porous spherical material of Example 1, and b is the SEM image of the geopolymer porous spherical material of Comparative Example 1; from Figure 3 It can be seen that the material without added micro-nano bubble water has uneven pore size.

[0080] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for preparing porous spherical geopolymer materials, characterized in that, Includes the following steps: 1) After mixing tailings and fly ash at a mass ratio of 1:1-5, the mixture is ball-milled until homogeneous to obtain a mixed powder; 2) Mix the mixed powder with micro-nano bubble water containing alkali activator to obtain a geopolymer slurry; 3) Mix hydrogen peroxide solution, micro-nano bubble water and geopolymer slurry, stir and foam to obtain foamed slurry; 4) Add the foaming slurry to dimethyl silicone oil to form microspheres. After the microspheres have solidified and shaped, remove them, dry them, wash them, and then dry and cure them to obtain cured microspheres. 5) The cured microspheres are calcined to obtain porous spherical materials of geopolymer.

2. The method for preparing geopolymer porous spherical materials according to claim 1, characterized in that, In step 1), one or more of the following characteristics are present: The mass ratio of tailings to fly ash is 1:1.8-3.5; The ball mill has a ball-to-material ratio of 2-2.5:1, a rotation speed of 400-450 rpm, and a time of 1-4 hours.

3. The method for preparing geopolymer porous spherical materials according to claim 2, characterized in that, In step 1), the mass ratio of tailings to fly ash is 1:1.9-2.

2.

4. The method for preparing geopolymer porous spherical materials according to claim 1, characterized in that, In step 2), one or more of the following characteristics are present: The alkaline activator is a mixture of sodium silicate and sodium hydroxide, wherein the mass ratio of the mixed powder, sodium silicate, and sodium hydroxide is 30:5:1.132-1.

18. The modulus of the micro-nano bubble water containing the alkali activator is 1.2-1.4; The micro / nano bubble water containing an alkaline activator also contains sodium dodecyl sulfate, and the amount of sodium dodecyl sulfate added is 2-4 wt% of the mass of the mixed powder. The method for achieving uniform mixing is stirring, with a stirring speed of 450-500 rpm and a stirring time of 15-20 min; The micro-nano bubble water is prepared using a micro-nano bubble generator with the following parameters: gas flow rate 450-500 mL / min, water flow rate 500-550 L / min, mixing rate 300-350 L / min, and a total treatment time of 1 h based on a water volume of 1 L.

5. The method for preparing geopolymer porous spherical materials according to claim 4, characterized in that, The preparation method of the micro-nano bubble water containing alkali activator is as follows: sodium silicate powder, sodium hydroxide and micro-nano bubble water are mixed and stirred at 60-70℃ until completely dissolved, then sodium dodecyl sulfate is added, stirred and mixed evenly, and cooled to room temperature to obtain micro-nano bubble water containing alkali activator.

6. The method for preparing geopolymer porous spherical materials according to claim 1, characterized in that, In step 3), one or more of the following characteristics are present: The concentration of the hydrogen peroxide solution is 30 wt%; The hydrogen peroxide solution and micro / nano bubble water are mixed at a volume ratio of 0.5-1.5:1; The water-to-solid ratio of the foaming slurry is 0.5-0.6, and the solid mass of the water-to-solid ratio is based on the mass of the mixed powder. The micro-nano bubble water is prepared using a micro-nano bubble generator with the following parameters: gas flow rate 450-500 mL / min, water flow rate 500-550 L / min, mixing rate 300-350 L / min, and a total treatment time of 1 h based on a water volume of 1 L. The stirring and foaming time is 20-30 seconds.

7. The method for preparing geopolymer porous spherical materials according to claim 1, characterized in that, In steps 4) and 5), one or more of the following characteristics are present: The temperature of the dimethyl silicone oil is 70-80℃; The curing time for the microspheres is 15-20 minutes. Dry in a forced-air drying oven for 30-60 minutes, wash twice each with anhydrous ethanol and micro-nano bubble water, and then place in a forced-air drying oven for 10-12 hours. The calcination temperature is 500℃, and the calcination time is 3-5 hours.

8. Geopolymer porous spherical material prepared by the preparation method according to any one of claims 1-7.

9. The geopolymer porous spherical material according to claim 8, characterized in that, The Si / Al molar ratio of the geopolymer porous spherical material is 1.

45.

10. The application of the geopolymer porous spherical material according to claim 8 in the adsorption of toluene.

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