Activated fly ash-based catalysts, their preparation, and their application in the advanced oxidative degradation of organic pollutants in the liquid phase.

Abstract

This invention belongs to the fields of chemical engineering technology and environmental protection, and relates to an activated fly ash-based catalyst, its preparation, and its application in the advanced liquid-phase oxidative degradation of organic pollutants. The catalyst's raw materials include fly ash, an alkali activator, and an alcohol, wherein the mass ratio of fly ash to alcohol is 0.5–10:1, and the mass ratio of fly ash to alkali activator is 0.1–5.0:1. The preparation method mainly includes two combined steps: alcohol-alkali ball milling and low-temperature melting. First, fly ash is mechanically ball-milled in the presence of a certain amount of alkali and short-chain alcohol. Then, the activated fly ash catalyst is obtained through low-temperature melting calcination, washing, and drying. Compared with existing technologies, the fly ash-based catalyst preparation provided by this invention is characterized by being green and efficient, operating under mild conditions, and having a simple and easily scalable process. Furthermore, the activated fly ash does not require the introduction of other active metal components, resulting in low cost. The prepared catalyst also possesses advantages such as high activity, broad spectrum of activity, and good stability.

Description

Technical Field

[0001] This invention belongs to the fields of chemical engineering technology and environmental protection, and relates to a method for preparing an active fly ash-based catalyst. The catalyst obtained by this invention can be used for the liquid-phase advanced oxidation degradation and mineralization of organic pollutant waste gas and wastewater. Background Technology

[0002] Fly ash refers to the fine ash particles collected from flue gas during coal combustion, and its main components are Si, Al, and Fe. The reuse or recycling of fly ash has significant social and economic benefits in areas such as environmental pollution control, resource and energy conservation, and the development of high-value products.

[0003] Fly ash has a high degree of polymerization, high bond energy, stable chemical properties at room temperature, and low activity. Therefore, the activation research of fly ash has become a hot topic in the current research on fly ash applications. Commonly used activation methods for fly ash include mechanical activation, chemical activation, and thermal activation. (1) Mechanical activation improves the activity of fly ash by increasing the fineness of fly ash. There are two main types: sorting and grinding. Sorting is grouped according to the size of fly ash particles. It has low energy consumption, high efficiency, and low noise, but it does not change the shape of fly ash particles or destroy the surface structure of spherical glass, resulting in low utilization. Grinding refines the fly ash particles, increases the degree of structural irregularity and defects, and increases the chemical energy of fly ash particles, increasing their chemical instability and thus increasing their activity. (2) Chemical activation refers to the reaction of SiO2 or Al2O3 in fly ash with Ca(OH)2 under the action of activators, mainly alkaline activators or sulfate activators, to form hydrated calcium silicate (CSH) or hydrated calcium aluminate (CAH) and other gel products. (3) Thermal activation: The composition and phase structure of fly ash are changed by calcination or autoclaving to improve the activity of fly ash. The advantage is that it can be applied to precast and cast-in-place components like cement, but it consumes a lot of energy, has high investment costs, and may lose activity if stored for a long time.

[0004] Patent CN118079917 A provides a method for preparing a catalytic material based on fly ash for denitrification. First, magnetic materials in the fly ash substrate are selected through wet slag magnetic separation. Then, oxygen-enriched ball milling is performed using hydrogen peroxide as an aid. The collisions and friction between material particles activate and generate oxygen vacancies on the surface. Finally, plasma discharge modification is performed using oxygen to obtain a catalytic material with abundant oxygen vacancies and high redox activity. Similarly, patent CN116586062 A provides a method for preparing a high electron mobility catalytic material based on fly ash. However, the entire preparation process involves multiple steps, including wet slag magnetic separation, oxygen-enriched high-energy ball milling, and plasma discharge, requiring significant investment in equipment, energy, and chemical reagents. Furthermore, this invention only reuses magnetic materials such as iron in the fly ash, while the remaining Si and Al components are not fully utilized.

[0005] Patent CN117899908 A discloses a catalyst using fly ash as a carrier, its preparation method, and its application. The catalyst consists of a fly ash carrier and an active component of N-doped copper-aluminum bimetallic oxide supported on the carrier, exhibiting high catalytic efficiency and a wide pH range suitable for treating organic wastewater. However, in this invention, the fly ash is only used as a carrier for the catalyst, and the fly ash undergoes no deep activation treatment beyond simple acidic solution soaking and washing pretreatment, resulting in low utilization efficiency. Patent CN109046298 A discloses a modified fly ash with adsorption and catalytic functions, its preparation method, and its application. The modified fly ash, as an adsorbent, not only has strong adsorption capacity for heavy metals and a large adsorption capacity but also catalyzes the Fenton reaction, promoting the degradation of organic pollutants in soil. However, in this invention, the fly ash has a high alkali fusion temperature and requires the addition of an active Fe component.

[0006] Existing patents on the use of fly ash as a raw material to prepare high-value-added functional materials, especially catalytic materials, mainly focus on its use as a catalyst carrier. In practice, other active components must be introduced. Furthermore, the activation degree of fly ash is often insufficient or incomplete, or the activation process is complex, costly, polluting, and involves cumbersome experimental procedures. Therefore, developing a green, environmentally friendly, and low-cost method for preparing fly ash-based catalysts, especially those with inherent high activity, is of great significance for the resource utilization of fly ash. Summary of the Invention

[0007] The purpose of this invention is to overcome the defects of the prior art and provide an active fly ash-based catalyst with high activity, broad spectrum and good stability, its preparation and its application in the advanced oxidative degradation of organic pollutants in the liquid phase.

[0008] The objective of this invention can be achieved through the following technical solution: an active fly ash-based catalyst, wherein the raw materials of the catalyst include fly ash raw materials, alkali activator and alcohol, wherein the mass ratio (solid-liquid ratio) of fly ash raw materials to alcohol is 0.5 to 10:1, and the mass ratio of fly ash raw materials to alkali activator is 0.1 to 5.0:1.

[0009] Furthermore, the mass ratio of fly ash raw material to alcohol is 2-6:1, and the mass ratio of fly ash raw material to alkali activator is 0.1-2:1.

[0010] Furthermore, the fly ash raw material used is industrial waste fly ash from coal-fired power plants, which is solid waste fly ash collected from the flue gas emitted by pulverized coal combustion. It usually has an Fe content higher than 0.5% and does not require any other pretreatment.

[0011] Furthermore, the alcohol is a short-chain alcohol, a low-carbon fatty alcohol with 1 to 4 carbon atoms, or a combination thereof, including methanol, ethanol, propanol, or butanol, preferably ethanol.

[0012] Furthermore, the alkali activator includes one or more of alkali metals, alkaline earth metal oxides, peroxides, hydroxides, and carbonates, preferably sodium hydroxide.

[0013] The present invention also provides a method for preparing an active fly ash-based catalyst, comprising the following steps: mixing fly ash raw material with an alkali activator and an alcohol in a ball mill for mechanical ball milling; then melting and calcining the ball-milled fly ash; and finally washing the resulting product until the pH value is close to neutral and drying to obtain an active fly ash-based catalyst.

[0014] Furthermore, the mechanical ball milling conditions are as follows: the ball milling frequency is 100-700Hz, preferably 500Hz, and the ball milling time is 1-5h, preferably 2.5h;

[0015] The melting and calcining conditions are as follows: the calcination temperature is 200-800℃, preferably 450℃, and the calcination time is 0.5-5h, preferably 4h.

[0016] Furthermore, the washing is performed using deionized water or a dilute acid solution.

[0017] This invention also provides an application of an activated fly ash-based catalyst, wherein the catalyst is used to treat wastewater containing organic pollutants, specifically including the following steps:

[0018] First, a certain amount of the activated fly ash catalyst is added to the wastewater containing organic pollutants, stirred, and adjusted to an appropriate pH and temperature. Then, an oxidant is added, and after a certain reaction time, the concentration of organic pollutants is determined by liquid chromatography, and the conversion efficiency is calculated. For organic pollutant exhaust gas, it can be introduced into deionized water through methods such as bubbling; other steps are the same as for wastewater treatment.

[0019] Furthermore, the organic pollutant may be one or more of chlorinated organic compounds such as o-chlorophenol and chlorobenzene, phenol, bisphenol A, o-aminophenol, etc.

[0020] Furthermore, the amount of the active fly ash catalyst is 100-1000 mg / L, preferably 400 mg / L.

[0021] Furthermore, the oxidant is selected from at least one of hydrogen peroxide, peracetic acid, persulfate, permonosulfate and ozone, preferably hydrogen peroxide.

[0022] Furthermore, the amount of hydrogen peroxide used is 0.1 to 10 ml / L, preferably 3 ml / L.

[0023] Furthermore, the oxidation temperature is 5–60°C, preferably 40°C.

[0024] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0025] 1. This invention innovatively adopts an activation method that combines alcohol-alkali assisted mechanical ball milling and low-temperature alkali melting, which can transform the stable crystalline phase structure of fly ash into an amorphous phase, resulting in a larger surface area and richer pore structure. The activation process has the advantages of simple process, low cost, low energy consumption and low environmental pollution.

[0026] 2. Through the present invention, Fe, Si, Al and other elements in fly ash will recombine in situ during the activation process to form bulk stable and highly dispersed Fe active species, directly transforming fly ash into an active fly ash catalyst with catalytic activity, thus eliminating the need to introduce other active metals, shortening the preparation process of fly ash-based catalysts and reducing costs.

[0027] 3. The activated fly ash catalyst provided by this invention improves the activity and stability of the Fe active component by ensuring that the active component is in situ and highly dispersed in the porous, large-surface-area bulk structure of the activated fly ash. This enables the catalyst to react with the oxidant to generate free radicals, which oxidize low-concentration organic pollutants, achieving efficient and stable catalytic oxidation of organic pollutants. At the same time, due to the mild reaction conditions and the indiscriminate oxidation of free radicals, the complete removal of recalcitrant organic compounds such as o-chlorophenol from wastewater can be guaranteed.

[0028] 4. In view of the shortcomings of the prior art, this invention provides a mild and green method to activate fly ash to prepare an active fly ash catalyst for the advanced oxidation degradation of organic pollutants in waste gas and wastewater. This solves the problems of low-end application (only as a carrier), complex process, high cost, resource waste and serious environmental pollution in the current reuse of fly ash as a catalytic material. It transforms fly ash from solid waste into a catalytic material with high catalytic activity. It not only solves the problems of fly ash storage and pollution, but also provides a way to increase the added value of fly ash utilization.

[0029] 5. The method for preparing fly ash-based catalysts provided by this invention can deeply destroy the original fly ash high-temperature sintered phase, which has low surface area, high density, is difficult to form, and lacks catalytic activity, thereby making it porous and amorphous, and generating an active phase in situ. It features green efficiency, mild conditions, simple process, and easy scalability. Furthermore, the activated fly ash does not require the introduction of other active metal components, resulting in low cost. The prepared catalyst also has advantages such as high activity, broad spectrum, and good stability, showing broad prospects for industrial applications. In addition, this invention has good social and economic benefits in promoting the resource utilization of industrial solid waste fly ash, turning waste into treasure, and treating waste with waste. Attached Figure Description

[0030] Figure 1 The image shows the SEM image of the original fly ash in Example 1.

[0031] Figure 2 The image shows the SEM spectrum of the fly ash catalyst product after activation treatment in Example 1. Detailed Implementation

[0032] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0033] The following detailed description of some embodiments of the present invention is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0034] In the following embodiments, unless otherwise specified, the raw materials or processing techniques are conventional commercially available raw materials or conventional processing techniques in the art. Unless otherwise specified, the functional components or structures are conventional components or conventional structures used in the art to achieve the corresponding functions.

[0035] Example 1

[0036] Step 1: Mix 10g of fly ash raw material from Power Plant A, 2.5ml of ethanol, and 12g of NaOH in a ball mill jar and place them in a ball mill for ball milling (ball milling frequency of 500Hz, ball milling time of 2.5h);

[0037] Step 2: Further melt and roast the ball milled fly ash obtained in Step 1 at a temperature of 450℃ for 4 hours.

[0038] Step 3: Wash the calcined solid from Step 2 with deionized water until the pH value is close to neutral. After washing, dry the solid to obtain the active fly ash catalyst.

[0039] Figure 1 This is the SEM image of the original fly ash from Example 1. Figure 2 This is a SEM image of the fly ash after activation treatment in Example 1. From... Figure 1 It can be seen that the original fly ash is mainly spherical, composed of microspheres, irregularly shaped debris, and porous particles (unburned carbon). The microspheres are hollow spheres formed during combustion and have uneven particle size. Figure 2 It can be seen that the original fly ash becomes broken after high-alkali ball milling and high-temperature melting. The spherical structure of the original fly ash breaks into small fragments, the specific surface area increases, and the number of active sites increases.

[0040] The activated fly ash catalyst obtained above was added to simulated wastewater containing 200 ppm o-chlorophenol, with the activated fly ash catalyst added at a concentration of 400 mg / L and the reaction temperature at 40℃. After stirring and adsorption for 30 min, the concentration of o-chlorophenol in the solution was measured. Then, hydrogen peroxide was added at a concentration of 3 ml / L, and the concentration of o-chlorophenol in the solution was measured after 10 min and 30 min of reaction. The concentration of o-chlorophenol in the simulated wastewater was detected by liquid chromatography, and the corresponding adsorption / degradation rate was calculated.

[0041] Example 2

[0042] Step 1: Mix 10g of fly ash raw material from Power Plant B, 2.5ml of ethanol, and 12g of NaOH in a ball mill jar and place them in a ball mill for ball milling (ball milling frequency of 500Hz, ball milling time of 2.5h);

[0043] Step 2: Further melt and roast the ball milled fly ash obtained in Step 1 at a temperature of 450℃ for 4 hours.

[0044] Step 3: Wash the calcined solid from Step 2 with deionized water until the pH value is close to neutral. After washing, dry the solid to obtain the active fly ash catalyst.

[0045] The activated fly ash catalyst obtained above was added to simulated wastewater containing 200 ppm o-chlorophenol, with the activated fly ash catalyst added at a concentration of 400 mg / L and the reaction temperature at 40℃. After stirring and adsorption for 30 min, the concentration of o-chlorophenol in the solution was measured. Then, hydrogen peroxide was added at a concentration of 3 ml / L, and the concentration of o-chlorophenol in the solution was measured after 10 min and 30 min of reaction. The concentration of o-chlorophenol in the simulated wastewater was detected by liquid chromatography, and the corresponding adsorption / degradation rate was calculated.

[0046] Example 3

[0047] Step 1: Mix 10g of fly ash raw material from Power Plant C, 2.5ml of ethanol, and 12g of NaOH in a ball mill jar and place them in a ball mill for ball milling (ball milling frequency of 500Hz, ball milling time of 2.5h);

[0048] Step 2: Further melt and roast the ball milled fly ash obtained in Step 1 at a temperature of 450℃ for 4 hours.

[0049] Step 3: Wash the calcined solid from Step 2 with deionized water until the pH value is close to neutral. After washing, dry the solid to obtain the active fly ash catalyst.

[0050] The activated fly ash catalyst obtained above was added to simulated wastewater containing 200 ppm o-chlorophenol, with the activated fly ash catalyst added at a concentration of 400 mg / L and the reaction temperature at 40℃. After stirring and adsorption for 30 min, the concentration of o-chlorophenol in the solution was measured. Then, hydrogen peroxide was added at a concentration of 3 ml / L, and the concentration of o-chlorophenol in the solution was measured after 10 min and 30 min of reaction. The concentration of o-chlorophenol in the simulated wastewater was detected by liquid chromatography, and the corresponding adsorption / degradation rate was calculated.

[0051] Example 4

[0052] Step 1: Mix 10g of fly ash raw material from Power Plant D, 2.5ml of ethanol, and 12g of NaOH in a ball mill jar and place them in a ball mill for ball milling (ball milling frequency of 500Hz, ball milling time of 2.5h);

[0053] Step 2: Further melt and roast the ball milled fly ash obtained in Step 1 at a temperature of 450℃ for 4 hours.

[0054] Step 3: Wash the calcined solid from Step 2 with deionized water until the pH value is close to neutral. After washing, dry the solid to obtain the active fly ash catalyst.

[0055] The activated fly ash catalyst obtained above was added to simulated wastewater containing 200 ppm o-chlorophenol, with the activated fly ash catalyst added at a concentration of 400 mg / L and the reaction temperature at 40℃. After stirring and adsorption for 30 min, the concentration of o-chlorophenol in the solution was measured. Then, hydrogen peroxide was added at a concentration of 3 ml / L, and the concentration of o-chlorophenol in the solution was measured after 10 min and 30 min of reaction. The concentration of o-chlorophenol in the simulated wastewater was detected by liquid chromatography, and the corresponding adsorption / degradation rate was calculated.

[0056] Example 5

[0057] Step 1: Mix 10g of fly ash raw material from Power Plant E, 2.5ml of ethanol, and 12g of NaOH in a ball mill jar and place them in a ball mill for ball milling (ball milling frequency of 500Hz, ball milling time of 2.5h);

[0058] Step 2: Further melt and roast the ball milled fly ash obtained in Step 1 at a temperature of 450℃ for 4 hours.

[0059] Step 3: Wash the calcined solid from Step 2 with deionized water until the pH value is close to neutral. After washing, dry the solid to obtain the active fly ash catalyst.

[0060] The activated fly ash catalyst obtained above was added to simulated wastewater containing 200 ppm o-chlorophenol, with the activated fly ash catalyst added at a concentration of 400 mg / L and the reaction temperature at 40℃. After stirring and adsorption for 30 min, the concentration of o-chlorophenol in the solution was measured. Then, hydrogen peroxide was added at a concentration of 3 ml / L, and the concentration of o-chlorophenol in the solution was measured after 10 min and 30 min of reaction. The concentration of o-chlorophenol in the simulated wastewater was detected by liquid chromatography, and the corresponding adsorption / degradation rate was calculated.

[0061] Comparative Example 1

[0062] The fly ash raw material from power plant A in Example 1 was directly added to simulated wastewater containing 200 ppm o-chlorophenol, and the same method as in Example 1 was used for detection.

[0063] The main components of the fly ash raw materials from different power plants in Examples 1-5 are shown in Table 1 below:

[0064] Table 1. List of main components of the original fly ash from Examples 1 to 5

[0065] Example 1 Example 2 Example 3 Example 4 Example 5 <![CDATA[SiO2]]> 40.26％ 38.79％ 41.55％ 42.24％ 35.87％ <![CDATA[Al2O3]]> 32.90％ 29.86％ 22.52％ 29.86％ 30.92％ <![CDATA[Fe2O3]]> 2.90％ 3.41％ 7.64％ 3.59％ 4.91％ .

[0066] The activity test results of each embodiment and comparative example are shown in Table 2 below. Compared with the original fly ash, the activated fly ash catalyst prepared by this invention shows significant activity for the advanced oxidative degradation of o-chlorophenol, with a degradation rate of over 99% after 30 min of reaction. Furthermore, fly ash from different power plants (the main components of fly ash are shown in Table 1) all exhibited high catalytic activity after activation treatment by this invention, demonstrating the universality of the method.

[0067] Table 2 Activity data for Examples 1 to 5

[0068]

[0069]

[0070] Example 6

[0071] Step 1: Mix 10g of fly ash raw material from Power Plant A, 2.5ml of water, and 12g of NaOH in a ball mill jar and place it in a ball mill for ball milling (ball milling frequency of 500Hz, ball milling time of 2.5h);

[0072] Step 2: Further melt and roast the ball milled fly ash obtained in Step 1 at a temperature of 450℃ for 4 hours.

[0073] Step 3: Wash the calcined solid from Step 2 with deionized water until the pH value is close to neutral. After washing, dry the solid to obtain the active fly ash catalyst.

[0074] The activated fly ash catalyst obtained above was added to simulated wastewater containing 200 ppm o-chlorophenol, with the activated fly ash catalyst added at a concentration of 400 mg / L and the reaction temperature at 40℃. After stirring and adsorption for 30 min, the concentration of o-chlorophenol in the solution was measured. Then, hydrogen peroxide was added at a concentration of 3 ml / L, and the concentration of o-chlorophenol in the solution was measured after 10 min and 30 min of reaction. The concentration of o-chlorophenol in the simulated wastewater was detected by liquid chromatography, and the corresponding adsorption / degradation rate was calculated.

[0075] Example 7

[0076] Step 1: Mix 10g of fly ash raw material from Power Plant A and 12g of NaOH in a ball mill jar and place them in a ball mill for dry ball milling (ball milling frequency of 500Hz, ball milling time of 2.5h);

[0077] Step 2: Further melt and roast the ball milled fly ash obtained in Step 1 at a temperature of 450℃ for 4 hours.

[0078] Step 3: Wash the calcined solid from Step 2 with deionized water until the pH value is close to neutral. After washing, dry the solid to obtain the active fly ash catalyst.

[0079] The activated fly ash catalyst obtained above was added to simulated wastewater containing 200 ppm o-chlorophenol, with the activated fly ash catalyst added at a concentration of 400 mg / L and the reaction temperature at 40℃. After stirring and adsorption for 30 min, the concentration of o-chlorophenol in the solution was measured. Then, hydrogen peroxide was added at a concentration of 3 ml / L, and the concentration of o-chlorophenol in the solution was measured after 10 min and 30 min of reaction. The concentration of o-chlorophenol in the simulated wastewater was detected by liquid chromatography, and the corresponding adsorption / degradation rate was calculated.

[0080] Example 8

[0081] Step 1: Place 10g of fly ash raw material from Power Plant A and 12g of NaOH directly into a crucible for melting and roasting at a temperature of 450℃ for 4 hours.

[0082] Step 2: Wash the calcined solid from Step 1 with deionized water until the pH value is close to neutral. After washing, dry the solid to obtain the active fly ash catalyst.

[0083] The activated fly ash catalyst obtained above was added to simulated wastewater containing 200 ppm o-chlorophenol, with the activated fly ash catalyst added at a concentration of 400 mg / L and the reaction temperature at 40℃. After stirring and adsorption for 30 min, the concentration of o-chlorophenol in the solution was measured. Then, hydrogen peroxide was added at a concentration of 3 ml / L, and the concentration of o-chlorophenol in the solution was measured after 10 min and 30 min of reaction. The concentration of o-chlorophenol in the simulated wastewater was detected by liquid chromatography, and the corresponding adsorption / degradation rate was calculated.

[0084] Table 3. Activity data for Examples 1, 6-8

[0085]

[0086] The activity test results in Table 3 above show that the degradation rate of o-chlorophenol by the activated fly ash varies depending on the solvent used during the ball milling process, especially the degradation efficiency at 10 min. The best activity was achieved by ball milling a mixture of ethanol, sodium hydroxide, and fly ash followed by calcination. Nevertheless, the degradation rate of o-chlorophenol still reached over 98% after 30 min of reaction. This indicates that the significantly enhanced activity of fly ash after high-alkali ball milling and melting is mainly due to the increased surface area and pore structure of the fly ash, as well as the possible in-situ reconstruction of the active phase.

[0087] Example 9

[0088] Step 1: Mix 10g of fly ash raw material from Power Plant A, 1ml of ethanol, and 12g of NaOH in a ball mill jar and place them in a ball mill for ball milling (ball milling frequency of 500Hz, ball milling time of 2.5h);

[0089] Step 2: Further melt and roast the ball milled fly ash obtained in Step 1 at a temperature of 450℃ for 4 hours.

[0090] Step 3: Wash the calcined solid from Step 2 with deionized water until the pH value is close to neutral. After washing, dry the solid to obtain the active fly ash catalyst.

[0091] The activated fly ash catalyst obtained above was added to simulated wastewater containing 200 ppm o-chlorophenol, with the activated fly ash catalyst added at a concentration of 400 mg / L and the reaction temperature at 40℃. After stirring and adsorption for 30 min, the concentration of o-chlorophenol in the solution was measured. Then, hydrogen peroxide was added at a concentration of 3 ml / L, and the concentration of o-chlorophenol in the solution was measured after 10 min and 30 min of reaction. The concentration of o-chlorophenol in the simulated wastewater was detected by liquid chromatography, and the corresponding adsorption / degradation rate was calculated.

[0092] Example 10

[0093] Step 1: Mix 10g of fly ash raw material from Power Plant A, 10ml of ethanol, and 12g of NaOH in a ball mill jar and place them in a ball mill for ball milling (ball milling frequency of 500Hz, ball milling time of 2.5h);

[0094] Step 2: Further melt and roast the ball milled fly ash obtained in Step 1 at a temperature of 450℃ for 4 hours.

[0095] Step 3: Wash the calcined solid from Step 2 with deionized water until the pH value is close to neutral. After washing, dry the solid to obtain the active fly ash catalyst.

[0096] The activated fly ash catalyst obtained above was added to simulated wastewater containing 200 ppm o-chlorophenol, with the activated fly ash catalyst added at a concentration of 400 mg / L and the reaction temperature at 40℃. After stirring and adsorption for 30 min, the concentration of o-chlorophenol in the solution was measured. Then, hydrogen peroxide was added at a concentration of 3 ml / L, and the concentration of o-chlorophenol in the solution was measured after 10 min and 30 min of reaction. The concentration of o-chlorophenol in the simulated wastewater was detected by liquid chromatography, and the corresponding adsorption / degradation rate was calculated.

[0097] Table 4. Activity data for Examples 1, 9, and 10

[0098] Example 1 Example 9 Example 10 Adsorption rate (30 min) 10.4％ 9.7％ 9.2％ Degradation rate (10 min) 86.3％ 80.2％ 70.5％ Degradation rate (30 min) 99.6％ 98.7％ 96.3％

[0099] The activity test results in Table 4 above show that different amounts of ethanol used in the ball milling process resulted in varying degradation rates of o-chlorophenol in the resulting activated fly ash. Insufficient ethanol led to incomplete dissolution of sodium hydroxide, while excessive ethanol easily formed sodium ethoxide; both excessive and insufficient ethanol amounts affected the fly ash activity. The optimal ethanol concentration was between 1 ml and 10 ml, with 2.5 ml being the most suitable.

[0100] Example 11

[0101] Step 1: Mix 10g of fly ash raw material from Power Plant A, 2.5ml of ethanol, and 12g of NaOH in a ball mill jar and place them in a ball mill for ball milling (ball milling frequency of 500Hz, ball milling time of 2.5h);

[0102] Step 2: Further melt and roast the ball milled fly ash obtained in Step 1 at a temperature of 300℃ for 4 hours.

[0103] Step 3: Disperse the calcined solid from Step 2 in a deionized water bath at 50°C and heat and stir for 4 hours. Then wash with deionized water until the pH value is close to neutral. After washing, dry to obtain the active fly ash catalyst.

[0104] The activated fly ash catalyst obtained above was added to simulated wastewater containing 200 ppm o-chlorophenol, with the activated fly ash catalyst added at a concentration of 400 mg / L and the reaction temperature at 40℃. After stirring and adsorption for 30 min, the concentration of o-chlorophenol in the solution was measured. Then, hydrogen peroxide was added at a concentration of 3 ml / L, and the concentration of o-chlorophenol in the solution was measured after 10 min and 30 min of reaction. The concentration of o-chlorophenol in the simulated wastewater was detected by liquid chromatography, and the corresponding adsorption / degradation rate was calculated.

[0105] Example 12

[0106] Step 1: Mix 10g of fly ash raw material from Power Plant A, 2.5ml of ethanol, and 12g of NaOH in a ball mill jar and place them in a ball mill for ball milling (ball milling frequency of 500Hz, ball milling time of 2.5h);

[0107] Step 2: Further melt and roast the ball milled fly ash obtained in Step 1 at a temperature of 500℃ for 4 hours.

[0108] Step 3: Disperse the calcined solid from Step 2 in a deionized water bath at 50°C and heat and stir for 4 hours. Then wash with deionized water until the pH value is close to neutral. After washing, dry to obtain the active fly ash catalyst.

[0109] The activated fly ash catalyst obtained above was added to simulated wastewater containing 200 ppm o-chlorophenol, with the activated fly ash catalyst added at a concentration of 400 mg / L and the reaction temperature at 40℃. After stirring and adsorption for 30 min, the concentration of o-chlorophenol in the solution was measured. Then, hydrogen peroxide was added at a concentration of 3 ml / L, and the concentration of o-chlorophenol in the solution was measured after 10 min and 30 min of reaction. The concentration of o-chlorophenol in the simulated wastewater was detected by liquid chromatography, and the corresponding adsorption / degradation rate was calculated.

[0110] Example 13

[0111] Step 1: Mix 10g of fly ash raw material from Power Plant A, 2.5ml of ethanol, and 12g of NaOH in a ball mill jar and place them in a ball mill for ball milling (ball milling frequency of 500Hz, ball milling time of 2.5h);

[0112] Step 2: Further melt and roast the ball milled fly ash obtained in Step 1 at a temperature of 900℃ for 4 hours.

[0113] Step 3: Disperse the calcined solid from Step 2 in a deionized water bath at 50°C and heat and stir for 4 hours. Then wash with deionized water until the pH value is close to neutral. After washing, dry to obtain the active fly ash catalyst.

[0114] The activated fly ash catalyst obtained above was added to simulated wastewater containing 200 ppm o-chlorophenol, with the activated fly ash catalyst added at a concentration of 400 mg / L and the reaction temperature at 40℃. After stirring and adsorption for 30 min, the concentration of o-chlorophenol in the solution was measured. Then, hydrogen peroxide was added at a concentration of 3 ml / L, and the concentration of o-chlorophenol in the solution was measured after 10 min and 30 min of reaction. The concentration of o-chlorophenol in the simulated wastewater was detected by liquid chromatography, and the corresponding adsorption / degradation rate was calculated.

[0115] Table 5. Activity data for Examples 1, 11-13

[0116] Example 1 Example 11 Example 12 Example 13 Adsorption rate (30 min) 10.4％ 13.17％ 10.48％ 11.61％ Degradation rate (10 min) 86.3％ 19.89％ 54.80％ 23.43％ Degradation rate (30 min) 99.6％ 74.33％ 99.33％ 98.27％

[0117] The activity test results in Table 5 above show that the catalyst activities obtained by calcining the ball-milled fly ash support at different temperatures vary. Below 450℃, the catalyst activity decreases, possibly because the low calcination temperature prevents complete melting of sodium hydroxide, resulting in insufficient etching of the fly ash. The final degradation rate at 500℃ is similar to that at 450℃. At temperatures as high as 900℃, the active phase undergoes sintering, leading to a decrease in the degradation rate.

[0118] Example 14

[0119] Step 1: Mix 10g of fly ash raw material from Power Plant A, 2.5ml of ethanol, and 12g of NaOH in a ball mill jar and place them in a ball mill for ball milling (ball milling frequency of 500Hz, ball milling time of 2.5h);

[0120] Step 2: Further melt and roast the ball milled fly ash obtained in Step 1 at a temperature of 450℃ for 4 hours.

[0121] Step 3: Wash the calcined solid from Step 2 with deionized water until the pH value is close to neutral. After washing, dry the solid to obtain the active fly ash catalyst.

[0122] The activated fly ash catalyst obtained above was added to simulated wastewater containing 200 ppm phenol, with the activated fly ash catalyst added at a concentration of 400 mg / L and the reaction temperature at 40°C. After stirring and adsorption for 30 min, the concentration of phenol in the solution was measured. Then, hydrogen peroxide was added at a concentration of 3 ml / L, and the concentration of phenol in the solution was measured after 10 min and 30 min of reaction, respectively. The concentration of phenol in the simulated wastewater was detected by liquid chromatography, and the corresponding adsorption / degradation rate was calculated.

[0123] Example 15

[0124] Step 1: Mix 10g of fly ash raw material from Power Plant A, 2.5ml of ethanol, and 12g of NaOH in a ball mill jar and place them in a ball mill for ball milling (ball milling frequency of 500Hz, ball milling time of 2.5h);

[0125] Step 2: Further melt and roast the ball milled fly ash obtained in Step 1 at a temperature of 450℃ for 4 hours.

[0126] Step 3: Wash the calcined solid from Step 2 with deionized water until the pH value is close to neutral. After washing, dry the solid to obtain the active fly ash catalyst.

[0127] The activated fly ash catalyst obtained above was added to simulated wastewater containing 200 ppm chlorobenzene, with an added concentration of 400 mg / L and a reaction temperature of 40 °C. After stirring and adsorption for 30 min, the concentration of chlorobenzene in the solution was measured. Then, hydrogen peroxide was added at a concentration of 3 ml / L, and the concentration of chlorobenzene in the solution was measured after 10 min and 30 min of reaction. The concentration of chlorobenzene in the simulated wastewater was detected by liquid chromatography, and the corresponding adsorption / degradation rate was calculated.

[0128] Example 16

[0129] Step 1: Mix 10g of fly ash raw material from Power Plant A, 2.5ml of ethanol, and 12g of NaOH in a ball mill jar and place them in a ball mill for ball milling (ball milling frequency of 500Hz, ball milling time of 2.5h);

[0130] Step 2: Further melt and roast the ball milled fly ash obtained in Step 1 at a temperature of 450℃ for 4 hours.

[0131] Step 3: Wash the calcined solid from Step 2 with deionized water until the pH value is close to neutral. After washing, dry the solid to obtain the active fly ash catalyst.

[0132] The activated fly ash catalyst obtained above was added to simulated wastewater containing 200 ppm methylene blue, with the activated fly ash catalyst added at a concentration of 400 mg / L and the reaction temperature at 40°C. After stirring and adsorption for 30 min, the concentration of methylene blue in the solution was measured. Then, hydrogen peroxide was added at a concentration of 3 ml / L, and the concentration of methylene blue in the solution was measured after 10 min and 30 min of reaction, respectively. The concentration of methylene blue in the simulated wastewater was detected by ultraviolet spectrophotometer, and the corresponding adsorption / degradation rate was calculated.

[0133] Table 6. Activity data for Examples 1, 14-16

[0134] Example 1 Example 14 Example 15 Example 16 Adsorption rate (30 min) 10.4％ 12.8％ 13.2％ 20.2％ Degradation rate (10 min) 86.3％ 16.9％ 33.9％ 99.3％ Degradation rate (30 min) 99.6％ 99.6％ 75.8％ 99.7％

[0135] The activity test results in Table 6 above show that the catalyst obtained after activation of fly ash is effective in degrading different pollutants. The degradation rate of o-chlorophenol, phenol, and methylene blue can reach over 99.5% after 30 minutes of reaction. Although the effect on chlorobenzene is not as good, the degradation rate can still reach 75.8% after 30 minutes of reaction. This indicates that the activity of fly ash is greatly improved after alcohol-assisted mechanical ball milling and low-temperature melting, and it has universal applicability to different pollutants.

[0136] Example 17

[0137] The catalyst obtained by calcination in Example 1 was subjected to four cycles of degradation experiments. o-Chlorophenol was selected as a model chlorinated organic pollutant to simulate wastewater degradation. The concentration of chlorobenzene was 200 ppm, and the catalyst concentration was 0.4 g / L. 40 mg of activated fly ash catalyst was added to 100 ml of o-chlorophenol aqueous solution for pollutant adsorption-degradation simulation experiments (adsorption was performed for the first 30 minutes, followed by oxidative degradation). The hydrogen peroxide concentration was 3 ml / L. The initial pH of the reaction solution was adjusted to 3 using HNO3, and the reaction temperature was 40 °C.

[0138] Table 7 Activity Data Table of Example 17

[0139] Run 1 Run 2 Run 3 Run 4 Run 5 Adsorption rate (30 min) 2.9％ 6.9％ 5.0％ 5.3％ 5.7％ Degradation rate (10 min) 26.4％ 17.0％ 12.0％ 10.6％ 15.1％ Degradation rate (30 min) 99.0％ 97.8％ 98.1％ 96.0％ 94.1％

[0140] Example 18

[0141] The catalyst obtained by calcination in Example 7 was subjected to four cycles of degradation experiments. o-Chlorophenol was selected as a model chlorinated organic pollutant to simulate wastewater degradation. The concentration of chlorobenzene was 200 ppm, and the catalyst concentration was 0.4 g / L. 40 mg of activated fly ash catalyst was added to 100 ml of o-chlorophenol aqueous solution for pollutant adsorption-degradation simulation experiments (adsorption was performed for the first 30 minutes, followed by oxidative degradation). The hydrogen peroxide concentration was 3 ml / L. The initial pH of the reaction solution was adjusted to 3 using HNO3, and the reaction temperature was 40 °C.

[0142] Table 8 Activity Data Table of Example 18

[0143]

[0144] The cyclic experiments of the catalysts in Examples 1 and 7 show that the catalyst obtained by ball milling fly ash with ethanol and sodium hydroxide followed by low-temperature alkaline calcination exhibits higher stability, achieving a degradation rate of over 90% after 30 minutes of reaction following four cycles. However, the catalyst obtained by directly ball milling and calcining fly ash with sodium hydroxide shows poor stability, with a degradation rate of only 23.4% after 30 minutes of reaction following four cycles. This indicates that ethanol plays a significant role in the activation process of fly ash, facilitating the in-situ construction of the active phase.

[0145] The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0146] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0147] Furthermore, various embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. An active fly ash-based catalyst, characterized in that, The catalyst's raw materials include fly ash, an alkali activator, and an alcohol, wherein the mass ratio of fly ash to alcohol is 0.5~10:1, and the mass ratio of fly ash to alkali activator is 0.1~5.0:

1. The catalyst is prepared by the following method: fly ash raw material is mixed with alkali activator and alcohol, mechanically ball-milled, and then melt-calcined. The resulting product is washed and dried to obtain an active fly ash-based catalyst.

2. The activated fly ash-based catalyst according to claim 1, characterized in that, The mass ratio of fly ash raw material to alcohol is 2~6:1, and the mass ratio of fly ash raw material to alkali activator is 0.1~2:

1.

3. The activated fly ash-based catalyst according to claim 1, characterized in that, The fly ash raw material mentioned above is industrial waste fly ash from coal-fired power plants.

4. The activated fly ash-based catalyst according to claim 1, characterized in that, The alcohols mentioned are short-chain alcohols, low-carbon fatty alcohols with 1 to 4 carbon atoms and their combinations, including methanol, ethanol, propanol or butanol.

5. The activated fly ash-based catalyst according to claim 1, characterized in that, The alkaline activator includes one or more of the following: oxides, peroxides, hydroxides, and carbonates of alkali metals and alkaline earth metals.

6. A method for preparing an active fly ash-based catalyst as described in any one of claims 1 to 5, characterized in that, The process includes the following steps: mixing fly ash raw material with alkali activator and alcohol, mechanically ball milling, then melt-calcining, and washing and drying the resulting product to obtain an active fly ash-based catalyst.

7. The method for preparing the activated fly ash-based catalyst according to claim 6, characterized in that, The mechanical ball milling conditions are as follows: ball milling frequency is 100~700Hz, and ball milling time is 1-5h; The melting and calcining conditions are as follows: calcination temperature is 200~800℃, and calcination time is 0.5-5h.

8. The method for preparing the activated fly ash-based catalyst according to claim 6, characterized in that, The washing process involves using deionized water or a dilute acid solution.

9. The application of an active fly ash-based catalyst as described in any one of claims 1-5, characterized in that: The catalyst is used to treat wastewater containing organic pollutants.

10. The application of the activated fly ash-based catalyst according to claim 9, characterized in that, The catalyst is added in an amount of 100~1000 mg / L; An oxidant is also added during the treatment process. The oxidant is selected from at least one of hydrogen peroxide, peracetic acid, persulfate, and ozone.

11. The application of the activated fly ash-based catalyst according to claim 10, characterized in that, The persulfate mentioned is a permonosulfate.

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