Methods and applications for promoting CO2 fixation by fly ash carbonation based on the synergistic effect of ultraviolet radiation and Mg(OH)2 catalysis
By using ultraviolet radiation and Mg(OH)2 catalysis in synergistic treatment, the structure of fly ash is improved and a stable alkaline environment is provided, which solves the problem of low CO2 fixation efficiency of fly ash carbonation and achieves efficient and low-cost CO2 fixation effect, which is applicable to the field of building materials.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHANGHAI UNIVERSITY OF ELECTRIC POWER
- Filing Date
- 2026-03-13
- Publication Date
- 2026-07-10
AI Technical Summary
In existing technologies, the reaction rate of CO2 fixation by fly ash carbonation is slow and the CO2 absorption is low. Traditional treatment methods are costly, cause equipment corrosion and secondary pollution, lack synergistic control mechanisms, have limited catalytic effect when using Mg(OH)2 alone, and the effect of ultraviolet radiation is not significant.
A method for promoting CO2 fixation by carbonation of fly ash through the synergistic effect of ultraviolet radiation and Mg(OH)2 catalysis includes sample preparation, ultraviolet radiation pretreatment and carbonation reaction. Ultraviolet radiation changes the structure of fly ash and provides a suitable pH environment, while Mg(OH)2 maintains the stability of the reaction and synergistically improves the CO2 absorption efficiency.
It significantly improves the efficiency of CO2 carbonation from fly ash, with CO2 absorption reaching 70.77 g-CO2/kg-FA and carbonation efficiency increased by 31.8%. The process is simple, low-cost, and environmentally friendly, avoiding the need for high-temperature and high-pressure equipment, and is suitable for industrial promotion.
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Figure CN122352017A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the technical field of CO2 capture and utilization, specifically to a method for CO2 fixation by carbonation of fly ash based on the synergistic effect of ultraviolet radiation and Mg(OH)2 catalysis, and its application in the field of CO2 fixation. Background Technology
[0002] Fly ash is a major solid waste generated by coal-fired power plants. It contains a certain amount of alkaline oxides and has the potential to chemically absorb CO2. Fly ash carbonation for CO2 fixation technology can not only achieve permanent CO2 storage but also improve the stability of fly ash, making it a promising CO2 capture and utilization technology with potential applications in building materials and other fields.
[0003] However, directly carbonating untreated fly ash presents problems such as slow reaction rate, low CO2 absorption, and low reaction efficiency. Existing technologies include strong acid pretreatment or the addition of potent catalysts, but these methods often suffer from drawbacks such as high cost, equipment corrosion, and the introduction of secondary pollution. Mg(OH)₂, a weak base, is widely available, inexpensive, and environmentally friendly, providing a mild alkaline environment in aqueous solution; however, its catalytic effect on fly ash carbonation is limited when used alone. Ultraviolet radiation, as a physical pretreatment method, is high-energy and pollution-free, but its effect on improving fly ash reactivity is not significant when relying solely on it. Traditional treatment methods lack synergistic control mechanisms, often using catalysts or radiation treatment alone, without considering the organic combination of weak base catalysis with light radiation and other treatment methods, resulting in a very limited improvement in fly ash carbonation efficiency.
[0004] Therefore, how to develop a simple, economical, efficient and environmentally friendly method to overcome the shortcomings of existing technologies and significantly improve the efficiency of fly ash carbonation of CO2 is a technical problem that urgently needs to be solved in this field. Summary of the Invention
[0005] This invention was made to solve the above-mentioned problems, and its purpose is to provide a method and application for promoting the carbonation and fixation of CO2 by fly ash based on the synergistic effect of ultraviolet radiation and Mg(OH)2 catalysis.
[0006] This invention provides a method for promoting CO2 fixation by fly ash carbonation based on the synergistic effect of ultraviolet radiation and Mg(OH)2 catalysis, characterized by the following steps: S1: Sample preparation: Dry fly ash and Mg(OH)2 catalyst are mixed in deionized water and stirred to form a homogeneous slurry; S2: Ultraviolet radiation pretreatment: The slurry is placed under an ultraviolet light source for radiation pretreatment; S3: Carbonation reaction: The radiation-pretreated slurry is transferred to a reaction vessel, and CO2 is introduced under preset conditions to carry out a carbonation reaction, thereby fixing CO2 and obtaining the fly ash carbonation product.
[0007] The method for promoting CO2 fixation by carbonation of fly ash based on the synergistic effect of ultraviolet radiation and Mg(OH)2 catalysis provided by the present invention may also have the following characteristics: wherein, in S1, the drying conditions of fly ash are: drying temperature of 100-110℃, drying time of 20-28h, and the moisture content of the dried fly ash is ≤0.5%.
[0008] The method for promoting CO2 fixation by carbonation of fly ash based on the synergistic effect of ultraviolet radiation and Mg(OH)2 catalysis provided by the present invention may also have the following characteristics: in S1, the mass of Mg(OH)2 catalyst is 5%-20% of the mass of fly ash, the amount of deionized water added is 130-170mL per 10g of fly ash, the stirring speed is 450-550rpm, and the stirring time is 25-35min.
[0009] The method for promoting CO2 fixation by carbonation of fly ash based on the synergistic effect of ultraviolet radiation and Mg(OH)2 catalysis provided by the present invention may also have the following feature: wherein the mass of the Mg(OH)2 catalyst is 5% of the mass of the fly ash.
[0010] The method for promoting the carbonation and CO2 fixation of fly ash based on the synergistic effect of ultraviolet radiation and Mg(OH)2 catalysis provided by the present invention may also have the following characteristics: wherein, in S2, the wavelength of the ultraviolet light source is 330-350nm, the power is 15-25W, the distance between the ultraviolet light source and the slurry surface is 8-12cm, and the radiation pretreatment time is 6-48h.
[0011] The method for promoting the carbonation and CO2 fixation of fly ash based on the synergistic effect of ultraviolet radiation and Mg(OH)2 catalysis provided by the present invention may also have the following feature: wherein the radiation pretreatment time is 24h.
[0012] The method for promoting the carbonation and CO2 fixation of fly ash based on the synergistic effect of ultraviolet radiation and Mg(OH)2 catalysis provided by the present invention may also have the following features: wherein, in S3, the preset conditions are temperature, pressure and stirring conditions, the temperature is 20-60℃, the pressure is 0.8-1.2MPa, and the stirring speed is 450-550rpm.
[0013] The method for promoting CO2 fixation by fly ash carbonation based on the synergistic effect of ultraviolet radiation and Mg(OH)2 catalysis provided by the present invention may also have the following features: S4: product post-treatment, performing solid-liquid separation, washing and drying on the fly ash carbonation product to obtain a solid product.
[0014] This invention also provides the application of a method for CO2 fixation by promoting carbonation of fly ash based on the synergistic effect of ultraviolet radiation and Mg(OH)2 catalysis in the field of CO2 fixation. The method is characterized by the following: the method is a method for promoting CO2 fixation by promoting carbonation of fly ash based on the synergistic effect of ultraviolet radiation and Mg(OH)2 catalysis, the method makes the CO2 absorption of fly ash not less than 65 g-CO2 / kg-FA, and the carbonation efficiency is increased by more than 30% compared with the original fly ash without the method treatment.
[0015] The role and effect of invention
[0016] The method and application of the present invention, which promotes CO2 fixation by carbonation of fly ash based on the synergistic effect of ultraviolet radiation and Mg(OH)2 catalysis, have the following beneficial effects:
[0017] This invention addresses the problems of low reaction efficiency, harsh reaction conditions, easy side reactions of catalysts, and lack of synergistic regulation mechanisms in traditional fly ash carbonation technology. It proposes a method for promoting CO2 fixation through fly ash carbonation based on the synergistic effect of ultraviolet radiation and Mg(OH)2 catalysis. This innovatively combines ultraviolet physical pretreatment with weakly alkaline chemical catalysis by Mg(OH)2, producing a synergistic effect of "1+1>2". The mechanism of action of this invention is as follows: ultraviolet radiation pretreatment not only changes the specific surface area and pore structure of fly ash, increasing the reaction contact surface, but also promotes the dissolution of alkaline substances in the fly ash; while Mg(OH)2 maintains a stable and suitable pH environment in the reaction system. The synergistic effect of both significantly improves the efficiency of CO2 carbonation from fly ash. The entire process uses only water, fly ash, low-cost Mg(OH)2, and ultraviolet radiation, produces no harmful byproducts, requires no high-temperature or high-pressure equipment, has low industrial energy consumption, and achieves the goal of waste-to-waste and green low-carbon development. This method has simple operation steps, and the process parameters (such as ultraviolet wavelength, power, time, catalyst ratio, etc.) are clear and easy to control, which is conducive to the implementation and promotion of coal-fired power plants. Attached Figure Description
[0018] Figure 1This is a thermogravimetric analysis curve of sample FAC-0.5-24 in Example 1 of the present invention.
[0019] Figure 2 These are SEM images and surface scan distribution maps of Mg, O, and Ca elements in sample FAC-0.5-24 (treated under optimal conditions) before and after the carbonation reaction in Example 1 of this invention. Figure 2 (a) Figure 2 The images in the middle (d) are SEM images and surface scan distribution maps of Mg, O, and Ca elements before the carbonation reaction. Figure 2 (e) Figure 2 The images in the middle (h) are SEM images and surface scan distribution maps of Mg, O, and Ca elements after the carbonation reaction. Figure 2 (i) is the SEM image labeled after the carbonation reaction.
[0020] Figure 3 This is a comparison of the XRD patterns of different samples in Example 1 of the present invention.
[0021] Figure 4 This is a graph showing the effect of different process parameters on CO2 absorption in an embodiment of the present invention. Figure 4 In the middle (a), there is a graph showing the effect of different amounts of Mg(OH)2 added on CO2 absorption without ultraviolet radiation. Figure 4 (b) is a graph showing the effect of different amounts of Mg(OH)2 added on CO2 absorption after 24 hours of ultraviolet radiation. Figure 4 (c) is a graph showing the effect of different ultraviolet radiation durations on CO2 absorption. Detailed Implementation
[0022] To make the technical means, creative features, objectives and effects of this invention easy to understand, the following embodiments, in conjunction with the accompanying drawings, specifically illustrate the method and application of this invention for promoting the carbonation and fixation of CO2 in fly ash based on the synergistic effect of ultraviolet radiation and Mg(OH)2 catalysis.
[0023] Example 1
[0024] This embodiment provides a method for promoting CO2 fixation by carbonation of fly ash based on the synergistic effect of ultraviolet radiation and Mg(OH)2 catalysis, including the following steps:
[0025] S1: Sample preparation: The dried fly ash and Mg(OH)2 catalyst were mixed in deionized water and stirred to form a homogeneous slurry, specifically as follows:
[0026] Collect fly ash from the power plant and place it in a drying oven. Dry it at 105℃ for 24 hours. Continuous drying removes free and adsorbed water from the fly ash, preventing moisture from interfering with the concentration of the subsequent mixed slurry and the efficiency of ultraviolet radiation. The moisture content of the dried fly ash must be controlled below 0.5% to ensure the precise ratio of catalyst to fly ash in the subsequent process.
[0027] Weigh 10g of dried fly ash and 0.5g of analytical grade Mg(OH)2 powder, place them in a beaker, and add 150ml of deionized water.
[0028] Place the beaker on a magnetic stirrer and stir at 500 rpm for 30 minutes at room temperature (20-25℃) to fully mix the fly ash, Mg(OH)2 and deionized water, so that Mg(OH)2 is evenly dispersed on the surface of the fly ash particles, resulting in a uniform grayish-white slurry.
[0029] S2: Ultraviolet Radiation Pretreatment: The slurry is placed under an ultraviolet light source for radiation pretreatment, specifically:
[0030] Pour the above slurry into a transparent quartz petri dish, and cover the opening of the petri dish with plastic wrap (the plastic wrap has small holes to allow gas exchange, while preventing a large amount of CO2 from entering the air and causing premature reaction, and maintaining the humidity of the system).
[0031] A 340nm wavelength, 20W ultraviolet lamp was fixed 10cm directly above the slurry surface and subjected to continuous irradiation pretreatment for 24 hours. This sample was designated FA-0.5-24.
[0032] S3: Carbonation reaction: The slurry pretreated by radiation is transferred to a reaction vessel. Under preset conditions, CO2 is introduced to carry out a carbonation reaction. The CO2 is then fixed to obtain the fly ash carbonation product, specifically:
[0033] The slurry, after radiation pretreatment, was transferred entirely into the lining of a 500mL high-pressure reactor. After sealing the reactor, N2 was first introduced to purge air, followed by CO2 gas until the reaction pressure reached 1MPa. The reaction temperature was set to 40℃, and the stirring paddle was continuously stirred at 500rpm to carry out the carbonation reaction and fix the CO2.
[0034] During the reaction, the CO2 consumption is monitored in real time using a gas mass flow meter until the consumption stabilizes (usually after 30-60 minutes of reaction), at which point the reaction is stopped, yielding fly ash carbonation products with CaCO3 as the main product.
[0035] S4: Product post-processing and characterization. The fly ash carbonation products were subjected to solid-liquid separation, washing, and drying to obtain a solid product. The CO2 absorption of the solid product was calculated, and its characteristics were analyzed. Specifically:
[0036] After the reaction was complete, the slurry (i.e., the fly ash carbonation product) was removed, the solid product was separated by filtration, washed with deionized water, and finally dried at 105°C to constant weight. This sample was designated as FAC-0.5-24.
[0037] The CO2 absorption and characteristics of the solid products were characterized by thermogravimetric analysis (TGA), X-ray diffraction (XRD), and scanning electron microscopy (SEM).
[0038] Figure 1 This is a thermogravimetric analysis curve of sample FAC-0.5-24 in Example 1 of the present invention, used to accurately calculate CO2 absorption.
[0039] CO2 absorption: such as Figure 1 As shown, the CO2 absorption of the FAC-0.5-24 sample was calculated to be 70.77 g-CO2 / kg-FA based on the TGA weight loss rate in the 400-600℃ range (corresponding to CaCO3 decomposition) determined by the DTG curve through thermogravimetric analysis (TGA, air atmosphere, heating to 1000℃ at 10℃ / min).
[0040] Figure 2 These are SEM images and surface scan distribution maps of Mg, O, and Ca elements in sample FAC-0.5-24 (treated under optimal conditions) before and after the carbonation reaction in Example 1 of this invention. Figure 2 (a) Figure 2 The images in the middle (d) are SEM images and surface scan distribution maps of Mg, O, and Ca elements before the carbonation reaction. Figure 2 (e) Figure 2 The images in the middle (h) are SEM images and surface scan distribution maps of Mg, O, and Ca elements after the carbonation reaction. Figure 2 (i) is the SEM image labeled after the carbonation reaction.
[0041] SEM-EDS analysis: Experimental results are as follows Figure 2 (a) Figure 2 As shown in (h), EDS surface scanning revealed that Ca and O elements were enriched in the coating layer on the surface of fly ash particles, while the Mg element signal was uniformly enhanced after the carbonation reaction, confirming that Mg(OH)2 participated in the reaction and was distributed in the product.
[0042] like Figure 2 As shown in (i), after the carbonation reaction, the surface of fly ash particles is covered with a large number of fine and dense products.
[0043] Figure 3This is a comparison of XRD patterns of different samples in Example 1 of the present invention. FA-0.5-0 is a sample with only 0.5g Mg(OH)2 added, without radiation pretreatment and without CO2 passage; FA-0.5-24 is a sample with 0.5g Mg(OH)2 added and irradiated for 24h, but without CO2 passage; FAC-0.5-0 is a sample with 0.5g Mg(OH)2 added, without radiation pretreatment, but subjected to carbonation; FAC-0.5-24 is a sample with 0.5g Mg(OH)2 added and irradiated for 24h, followed by carbonation (the synergistic group of the present invention). The figure shows that the characteristic peak of CaCO3 is significantly enhanced after synergistic treatment.
[0044] XRD analysis: Experimental results are as follows Figure 3 As shown. Original sample (not shown in the figure): The untreated fly ash sample mainly contains characteristic diffraction peaks such as quartz (SiO2), and no obvious characteristic peaks of calcium carbonate (CaCO3) are observed.
[0045] The spectrum of the FA-0.5-0 sample was basically consistent with that of the original sample, indicating that the addition of Mg(OH)2 catalyst alone would not cause significant changes in the fly ash phase or generate new carbonate products under conditions without CO2 flow.
[0046] The spectra of sample FA-0.5-24 were not significantly different from those of sample FA-0.5-0, indicating that the addition of Mg(OH)2 catalyst and ultraviolet radiation pretreatment themselves did not cause significant changes in the fly ash phase, nor did they generate new carbonate products.
[0047] In the spectra of both FAC-0.5-0 and FAC-0.5-24 samples, characteristic peaks of calcite-type CaCO3 were observed at 2θ=29.4°, indicating that the carbonation process was realized.
[0048] Example 2
[0049] This example investigates the effect of Mg(OH)2 addition on CO2 absorption under two conditions: no UV radiation and UV radiation for 24 hours. Different solid products were prepared by varying the amount of Mg(OH)2 added. Except for the different amounts of Mg(OH)2 added (0g, 0.5g, 1.0g, 1.5g, 2.0g), the other operations were the same as in Example 1.
[0050] Figure 4 This is a graph showing the effect of different process parameters on CO2 absorption in Example 2 of the present invention. Figure 4 In the middle (a), there is a graph showing the effect of different amounts of Mg(OH)2 added on CO2 absorption without ultraviolet radiation. Figure 4(b) is a graph showing the effect of different amounts of Mg(OH)2 added on CO2 absorption after 24 hours of ultraviolet radiation. Figure 4 (c) is a graph showing the effect of different ultraviolet radiation durations on CO2 absorption.
[0051] Experimental results are as follows Figure 4 (a) and Figure 4 As shown in Figure (b), when the amount of Mg(OH)2 added is 0.5 g (5%), the CO2 absorption increases significantly compared to the sample without added Mg(OH)2, reaching peak values of 49.52 g-CO2 / kg-FA and 70.77 g-CO2 / kg-FA, respectively. When the amount of Mg(OH)2 added is further increased, the CO2 absorption decreases, indicating that there is an optimal range for the amount of Mg(OH)2 added. Too low a concentration results in insufficient alkaline catalytic environment; too high a concentration (>5%) leads to excessive insoluble Mg(OH)2 particles clogging the fly ash pores, hindering CO2 mass transfer, and consequently reducing the absorption.
[0052] Example 3
[0053] This embodiment investigates the effect of ultraviolet radiation pretreatment on CO2 absorption. The amount of Mg(OH)2 added is kept at 0.5g. Different solid products are prepared by changing the ultraviolet radiation pretreatment time. Except for the ultraviolet radiation pretreatment time (0h, 6h, 18h, 24h, 30h, 36h), the other operations are the same as in Example 1.
[0054] Experimental results are as follows Figure 4 As shown in (c), CO2 absorption increases with irradiation time, reaching a maximum at 24 hours, and then decreases slightly. This indicates that 24 hours is the optimal point for UV activation; excessively long irradiation may lead to excessive evaporation of moisture from the slurry or adverse physicochemical changes.
[0055] Table 1. Comparison of the effects of different treatment methods on CO2 absorption.
[0056] Experimental group <![CDATA[Dosage of Mg(OH)2 / g]]> Duration of ultraviolet radiation / h <![CDATA[CO2 uptake / g-CO2 / kg-FA]]> Carbonation efficiency / % Blank group (untreated fly ash) 0 0 32.11 26.51 <![CDATA[Only the Mg(OH)2 group]]> 0.5 0 49.52 40.80 Ultraviolet radiation group only 0 24 41.02 33.80 This invention's collaborative group 0.5 24 70.77 58.31
[0057] As shown in Table 1, combined with the experimental results of Examples 2-3, the CO2 absorption of the synergistic group (0.5g Mg(OH)2 + 24h ultraviolet radiation) sample FAC-0.5-24 of this invention reached 70.77g-CO2 / kg-FA, with a carbonation efficiency of 58.31%. Compared with the blank group, the carbonation efficiency increased by 31.8%. This is because Mg(OH)2, as a weak base catalyst, provides a mild and stable alkaline environment in aqueous solution, which can promote the conversion of CO2 to carbonate ions, while avoiding the side reactions that may be caused by strong bases. Ultraviolet radiation can promote the structural modification of fly ash and the dissolution of active components. The synergistic effect of "Mg(OH)2 + ultraviolet radiation" significantly improves the CO2 absorption capacity of fly ash, which is significantly better than single treatment, proving that the two can overcome the efficiency bottleneck of single technology through the synergy of pH adjustment and structural modification.
[0058] Therefore, the method of CO2 fixation by carbonation of fly ash based on the synergistic effect of ultraviolet radiation and Mg(OH)2 catalysis can be applied to the field of CO2 fixation.
[0059] The role and effect of the embodiments
[0060] The method and application of the present invention, which promotes CO2 fixation by carbonation of fly ash based on the synergistic effect of ultraviolet radiation and Mg(OH)2 catalysis, have the following beneficial effects:
[0061] This invention addresses the problems of low reaction efficiency, harsh reaction conditions, easy side reactions of catalysts, and lack of synergistic regulation mechanisms in traditional fly ash carbonation technology. It proposes a method for promoting CO2 fixation through fly ash carbonation based on the synergistic effect of ultraviolet radiation and Mg(OH)2 catalysis. This innovatively combines ultraviolet physical pretreatment with weak-base chemical catalysis of Mg(OH)2, producing a synergistic effect of "1+1>2". The sample FAC-0.5-24 prepared using this method achieved a CO2 absorption of 70.77 g-CO2 / kg-FA, with a carbonation efficiency of 58.31%, representing a 31.8% improvement in carbonation efficiency compared to untreated fly ash (CO2 absorption of 32.11 g-CO2 / kg-FA). Furthermore, it also significantly improved CO2 absorption compared to samples using Mg(OH)2 catalysis alone and samples pretreated with ultraviolet radiation alone.
[0062] The mechanism of action of this invention is as follows: ultraviolet radiation pretreatment alters the specific surface area and pore structure of fly ash, increasing the reaction contact surface and promoting the dissolution of alkaline substances in the fly ash bulk; while Mg(OH)2 provides a suitable pH environment, maintaining the stability of the reaction system, promoting the conversion of CO2 to carbonate ions, and avoiding side reactions that may be caused by strong alkali. The synergistic effect of these two factors combines the "active sites" created by ultraviolet radiation with the "alkaline microenvironment" provided by Mg(OH)2, resulting in a significant improvement in the efficiency of CO2 carbonation from fly ash.
[0063] The entire process uses only water, fly ash, low-cost Mg(OH)2, and ultraviolet light, producing no harmful byproducts and requiring no harsh reaction conditions such as high temperature and high pressure. The carbonation reaction can be carried out under mild conditions of 20-60℃ and 0.8-1.2MPa, while the ultraviolet radiation pretreatment is conducted at room temperature and pressure. This results in low energy consumption for industrial application and simple equipment requirements, facilitating widespread industrial adoption. Compared to traditional methods, this avoids equipment corrosion problems caused by strong acid pretreatment and the side reaction risks associated with adding potent catalysts, achieving the goal of waste-to-waste treatment and green, low-carbon development.
[0064] The method of this invention has simple operation steps, and the process parameters (such as ultraviolet wavelength, power, time, catalyst ratio, etc.) are clear and easy to control, making it highly operable and beneficial for the implementation and promotion of coal-fired power plants.
[0065] Those skilled in the art should understand that this invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to this invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.
Claims
1. A method for CO2 fixation by carbonation of fly ash based on the synergistic effect of ultraviolet radiation and Mg(OH)2 catalysis, characterized in that, Includes the following steps: S1: Sample preparation: The dried fly ash and Mg(OH)2 catalyst were mixed in deionized water and stirred to form a uniform slurry; S2: Ultraviolet radiation pretreatment: The slurry is placed under an ultraviolet light source for radiation pretreatment; S3: Carbonation reaction: The slurry pretreated by radiation is transferred to a reaction vessel, and CO2 is introduced under preset conditions to carry out a carbonation reaction. The CO2 is then fixed to obtain fly ash carbonation products.
2. The method for CO2 fixation by fly ash carbonation based on the synergistic effect of ultraviolet radiation and Mg(OH)2 catalysis as described in claim 1, characterized in that: in, In S1, the drying conditions for fly ash are as follows: drying temperature: 100-110℃, drying time: 20-28h, and the moisture content of the dried fly ash is ≤0.5%.
3. The method for CO2 fixation by fly ash carbonation based on the synergistic effect of ultraviolet radiation and Mg(OH)2 catalysis as described in claim 1, characterized in that: in, In S1, the mass of Mg(OH)2 catalyst is 5%-20% of the mass of fly ash, the amount of deionized water added is 130-170mL per 10g of fly ash, the stirring speed is 450-550rpm, and the stirring time is 25-35min.
4. The method for CO2 fixation by fly ash carbonation based on the synergistic effect of ultraviolet radiation and Mg(OH)2 catalysis as described in claim 3, characterized in that: in, The mass of the Mg(OH)2 catalyst is 5% of the mass of the fly ash.
5. The method for CO2 fixation by carbonation of fly ash based on the synergistic effect of ultraviolet radiation and Mg(OH)2 catalysis according to claim 1, characterized in that: in, In step S2, the wavelength of the ultraviolet light source is 330-350nm, the power is 15-25W, the distance between the ultraviolet light source and the surface of the slurry is 8-12cm, and the radiation pretreatment time is 6-48h.
6. The method for CO2 fixation by carbonation of fly ash based on the synergistic effect of ultraviolet radiation and Mg(OH)2 catalysis as described in claim 5, characterized in that: in, The radiation pretreatment time is 24 hours.
7. The method for CO2 fixation by carbonation of fly ash based on the synergistic effect of ultraviolet radiation and Mg(OH)2 catalysis as described in claim 1, characterized in that: in, In S3, the preset conditions are temperature, pressure and stirring conditions: temperature is 20-60℃, pressure is 0.8-1.2MPa, and stirring speed is 450-550rpm.
8. The method for promoting CO2 fixation by fly ash carbonation based on the synergistic effect of ultraviolet radiation and Mg(OH)2 catalysis according to claim 1, characterized in that, Also includes: S4: Product post-processing, the fly ash carbonation product is subjected to solid-liquid separation, washing and drying to obtain a solid product.
9. The application of a method for CO2 fixation by synergistic promotion of fly ash carbonation based on ultraviolet radiation and Mg(OH)2 catalysis in the field of CO2 fixation, characterized in that: The method is the method as described in any one of claims 1-8, wherein the method enables the fly ash to absorb CO2 at a rate of not less than 65 g-CO2 / kg-FA, and the carbonation efficiency is increased by more than 30% compared to the original fly ash that has not been treated by the method.