A method for modifying fly ash

Abstract

The application discloses a fly ash modification method, relates to the technical field of comprehensive treatment of solid waste and wastewater, and belongs to a green fly ash modification preparation method and application. The fly ash modification method process is as follows: rotten biomass is subjected to acidification fermentation, and the fermentation supernatant is subjected to microwave cell wall breaking and filtration and then subjected to evaporation concentration treatment; fly ash is fully mixed with the concentrated fermentation liquid of the rotten biomass; the obtained mixture is subjected to warming and activation treatment, so that the acid in the fermentation liquid performs acid modification on the surface of the fly ash; and the acidified fly ash is subjected to water washing and drying treatment, so that modified fly ash is obtained. The fly ash modified by the method has a very high adsorption effect on alkaline dye ions. The method is a low-cost, simple and green fly ash modification process.

Description

Technical Field

[0001] This invention relates to fly ash modification technology, and more particularly to a technology for green modification of fly ash to adsorb organic ions in dyeing and printing wastewater. Background Technology

[0002] Fly ash, a major solid waste product of coal, my country's main energy source, has an annual output of up to 668 million tons. Large accumulations of fly ash occupy land resources, and the various heavy metals and harmful elements it contains, such as iron, aluminum, lead, mercury, chromium, cadmium, and arsenic, can severely pollute soil and water resources. The resulting dust also pollutes the air environment and endangers human health. Therefore, the proper disposal of fly ash has become a key concern.

[0003] Currently, the traditional method of treating fly ash is to add it as an additive to roadbed backfill, cement, concrete, and other building materials. This results in low added value and ineffective utilization of the metal elements in the fly ash, leading to resource waste. Coal burns at high temperatures in furnaces, and most mineral structures in fly ash melt and crystallize during high-temperature combustion, resulting in a large amount of crystalline minerals such as quartz and mullite in the fly ash. The physical structure of fly ash means that the abundant metal elements are encapsulated by non-catalytically active crystals, significantly inhibiting the exposure of active sites and greatly limiting its application in adsorption.

[0004] Currently, the main methods for modifying fly ash include acid modification, alkali modification, and plasma exchange. Previous studies have shown that most of these methods require the introduction of irritating and harmful chemicals, which, when released into the environment, will have a significant negative impact. Therefore, exploring new methods for fly ash modification and developing low-cost, simple, and environmentally friendly modification processes has become a common concern. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned deficiencies in the prior art and to provide a method for modifying fly ash, wherein the fly ash obtained by the modified method has a large adsorption effect on alkaline dyes.

[0006] The technical solution adopted by the present invention to solve the above problems is: a method for modifying fly ash, characterized in that: the decayed biomass raw material is crushed and an appropriate amount of water is added for fermentation treatment; the supernatant of the fermentation produced acid is filtered by fermentation bacteria and then concentrated by evaporation; the bio-acid concentrate is mixed with fly ash for activation treatment, and the activated fly ash is washed and dried.

[0007] The decaying biomass was acidified and fermented, and the supernatant was microwave-filtered and then concentrated by evaporation. Fly ash was then thoroughly mixed with the concentrated fermentation liquid from the decaying biomass. The resulting mixture was then activated by heating, allowing the acid in the fermentation liquid to modify the surface of the fly ash. The acidified fly ash was then washed and dried to obtain modified fly ash. The modified fly ash obtained by this method exhibits a high adsorption capacity for basic dye ions.

[0008] Preferably, the decaying biomass is one or more of decaying vegetables, decaying fruits, and decaying hyperaccumulating plants.

[0009] Preferably, the degree of decay of the biomass is defined as the percentage of decayed surface area of ​​the biomass ranging from 1% to 100%.

[0010] Preferably, the ratio of crushed biomass pulp to added water is (0.01~100):1.

[0011] Preferably, the fermentation temperature is 0~100℃ and the time is 1~720h.

[0012] Preferably, the supernatant after fermentation of decaying biomass to produce acid is subjected to microwave pyrolysis to break down the fermentation bacteria in the supernatant. The microwave pyrolysis power is 10~1000w, the time is 1~100min, and the vacuum filtration pressure is controlled between 0.85~0.95Mpa.

[0013] Preferably, the supernatant of fermentation acid production after cell wall disruption and filtration is subjected to evaporation and concentration treatment; the evaporation and concentration temperature is 40~110℃, and the time is 1~24h.

[0014] Preferably, the mass ratio of bio-acid concentrate to fly ash is (1~100):1.

[0015] Preferably, the activation temperature of the bio-acid concentrate and fly ash is 0~100℃, and the activation time is 1~48h.

[0016] Preferably, the activated fly ash is washed with deionized water until the water after washing and filtration is neutral, and finally the filtered fly ash is dried in an oven at a temperature of 100~110℃ for 24~48h.

[0017] Compared with existing technologies, this invention has the following advantages and effects: This invention provides a method for modifying fly ash, which involves fermenting decayed biomass, then concentrating the fermented acid solution; the resulting concentrated fermentation solution is mixed with fly ash for activation treatment to obtain activated fly ash. Because biomass is decomposed by microorganisms such as various molds and bacteria during decay, it produces a large amount of organic acids and aldehydes, exhibiting strong acidity. Concentrating the fermentation solution further increases the acid concentration, thus preparing for fly ash activation. The fermentation acid in the concentrated fermentation solution can effectively corrode the vitreous amorphous structure on the surface of fly ash, promoting the dissolution of acid-soluble substances such as soluble aluminum salts on the fly ash surface, thereby increasing the surface roughness of the fly ash, widening the pore structure, improving the specific surface area of ​​the fly ash, and enhancing the reactivity of fly ash-based catalysts. Furthermore, the acids in the fermentation concentrate are organic acids such as phenols and CH3COOH, which can increase the specific surface area of ​​fly ash through acid modification, effectively increasing the weak acid sites on the fly ash surface, which is beneficial for enhancing the adsorption performance of basic dye cations. This method is a low-cost, simple, and green fly ash modification process. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the processing device in Embodiment 1 of the present invention.

[0019] Figure 2 This is a graph showing the change in pH value of the fermentation slurry over fermentation time during the fermentation process in Example 1 of this invention. Detailed Implementation

[0020] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. The following embodiments are explanations of the present invention, but the present invention is not limited to the following embodiments.

[0021] A method for modifying fly ash includes the following steps: crushing decayed biomass raw materials and adding an appropriate amount of water for fermentation treatment; filtering the resulting fermentation acid supernatant with cell wall breaking bacteria and then evaporating and concentrating it; mixing the bio-acid concentrate with fly ash for activation treatment; and washing and drying the activated fly ash.

[0022] In this invention, the decaying biomass is one or more of decaying vegetables, decaying fruits, and decaying hyperaccumulating plants.

[0023] In this invention, the degree of decay of the biomass varies from 1% to 100% of the biomass surface decay area, preferably 20% to 80%, and more preferably 40% to 60%.

[0024] In this invention, the ratio of crushed biomass pulp to added water is (0.01~100):1, preferably (0.1~10):1.

[0025] Before mixing, the decaying biomass is crushed using a crushing method known to those skilled in the art, so that the crushed decaying biomass is in a slurry form.

[0026] In this invention, there are no special limitations on the type of fly ash; any type known to those skilled in the art can be used.

[0027] In this invention, the preferred method for mixing decomposed biomass and fly ash is stirring, grinding, or ball milling.

[0028] In this invention, the fermentation temperature is 0~100℃, preferably 50~80℃; the fermentation time is 1~720h, preferably 36h, and more preferably 72~360h.

[0029] In this invention, the supernatant after fermentation of decaying biomass to produce acid is subjected to microwave pyrolysis to break down the fermentation bacteria in the supernatant. The microwave pyrolysis power is 10~1000W, preferably 100~500W, more preferably 200~300W; the microwave pyrolysis time is 1~100min, preferably 10~80min, more preferably 20~50min; and the vacuum filtration pressure is controlled between 0.85~0.95MPa.

[0030] In this invention, the supernatant of fermentation acid production after cell wall disruption and filtration is subjected to evaporation and concentration treatment; the evaporation and concentration temperature is 40~110℃, preferably 105℃; the time is 1~24h, preferably 12h.

[0031] In this invention, the organic acids, aldehydes and other metabolites obtained by fermentation can be used as activators to activate fly ash.

[0032] In this invention, the mass ratio of bio-acid concentrate to fly ash is (1~100):1, preferably (30~60):1.

[0033] In this invention, the activation temperature of the bio-acid concentrate and fly ash is 0~100℃, preferably 60~80℃; the activation time is 1~48h, preferably 12~24h.

[0034] In this invention, the activated fly ash is washed with deionized water until the water after washing and filtration is neutral. Finally, the filtered fly ash is dried in an oven. The drying temperature is 100~110℃, preferably 105℃, and the drying time is 24~48h.

[0035] In this invention, after obtaining the blended fermentation product, the fermentation concentrate is mixed with fly ash to obtain activated fly ash.

[0036] Example 1

[0037] 100g of rotten apples were crushed into a pulp with 50g of water in a crusher. The pulp was then placed in a clean fermentation tank for fermentation at 60℃ for 576 hours. The supernatant was then subjected to microwave cell disruption at 200W for 30 minutes. The supernatant was then subjected to multi-stage filtration under vacuum pressure controlled between 0.85 and 0.95 MPa. The filtered supernatant was then concentrated by heating it in an evaporation tank at 105℃ for 24 hours. The apparatus is as follows. Figure 1 As shown;

[0038] The fermentation concentrate and fly ash were placed in a magnetic stirrer and heated (at 80°C for 24 hours) to activate the fly ash under the action of fermenting malic acid. The activated fly ash was then washed with deionized water and dried.

[0039] 5 mg of activated fly ash was placed in a centrifuge tube containing 50 mL of methylene blue (concentration 50 mg / L). After adsorption at 30°C for 48 h, the methylene blue dye concentration was 1.9 mg / L. This demonstrates that activated fly ash exhibits excellent adsorption performance for cationic methylene blue dyes, with a removal efficiency of up to 96.2%.

[0040] Figure 2 This is a curve showing the change in pH value of the fermentation slurry over fermentation time during the fermentation process, where the horizontal axis represents fermentation time (d) and the vertical axis represents pH value; Figure 2 It can be seen that when the fermentation time reaches 24 days, the pH value reaches its lowest point, the acidity is strongest, and the activation effect is best.

[0041] Table 1 shows the BET analysis results of activated fly ash. It can be seen that mesopores account for 84.38% of the total pore volume in the activated fly ash. Methylene blue has a molecular weight of 319.85 and a molecular size of 1.7 nm × 0.76 nm × 0.325 nm, classifying it as a large organic molecule. When the pore size of a porous material is less than 1.7 times the size of the adsorbate molecule, the repulsive effect between adsorbate molecules increases significantly, requiring higher adsorption energy. The size of the methylene blue molecule makes it difficult for it to enter the micropores. However, the mesopore ratio of activated fly ash increases significantly, which is highly favorable for the adsorption of methylene blue.

[0042] Table 1. BET analysis of fly ash

[0043] Sample <![CDATA[SBET(m 2 g −1 )]]> <![CDATA[VT (cm 3 g −1 )]]> <![CDATA[Vμ (cm 3 g −1 )]]> <![CDATA[VM (cm 3 g −1 )]]> DP (nm) DCP 510 0.698 0.138 0.589 5.580

[0044] Note: "SBET" represents specific surface area; "VT" represents total pore volume; "Vμ" represents micropore volume; "VM" represents mesopore volume; "DP" represents average pore size.

[0045] Example 2

[0046] 100g of rotten strawberries were crushed into a pulp with 40g of water in a blender. The pulp was then placed in a clean fermentation tank for fermentation at 80℃ for 240 hours. The supernatant was then subjected to microwave cell disruption at 200W for 30 minutes. The supernatant was then subjected to multi-stage filtration under vacuum pressure controlled between 0.85 and 0.95 MPa. Finally, the filtered supernatant was concentrated by heating it in an evaporation tank at 105℃ for 24 hours.

[0047] The fermentation concentrate and fly ash were placed in a magnetic stirrer and heated (at 80°C for 24 hours) to activate the fly ash under the action of fermenting acid from decaying strawberries. The activated fly ash was then washed with deionized water and dried.

[0048] 5 mg of activated fly ash was placed in a centrifuge tube containing 50 mL of methylene blue (50 mg / L concentration). Adsorption was performed at 30°C for 48 hours, resulting in a methylene blue dye concentration of 4.5 mg / L. This demonstrates that activated fly ash exhibits excellent adsorption performance for water-soluble cationic dyes, achieving a removal efficiency of up to 91%.

[0049] Example 3

[0050] 100g of rotten grapes were crushed into a pulp with 10g of water in a crusher. The pulp was then placed in a clean fermentation tank for fermentation at 80℃ for 360 hours. The supernatant was then subjected to microwave cell disruption at 200W for 30 minutes. The supernatant was then subjected to multi-stage filtration under vacuum pressure controlled between 0.85 and 0.95 MPa. Finally, the filtered supernatant was concentrated by heating it in an evaporation tank at 105℃ for 24 hours.

[0051] The fermentation concentrate and fly ash were placed in a magnetic stirrer and heated (at 80°C for 24 hours) to activate the fly ash under the action of fermenting acid from the putrefactive grapes. The activated fly ash was then washed with deionized water and dried.

[0052] 5 mg of activated fly ash was placed in a centrifuge tube containing 50 mL of methylene blue (50 mg / L concentration). Adsorption was performed at 30°C for 48 h, resulting in a methylene blue dye concentration of 2.1 mg / L. This demonstrates that activated fly ash exhibits excellent adsorption performance for cationic methylene blue dyes, achieving a removal efficiency of up to 95.8%.

[0053] Any content not described in detail in this specification is prior art known to those skilled in the art.

[0054] Although the present invention has been disclosed above with reference to embodiments, it is not intended to limit the scope of protection of the present invention. Any modifications and refinements made by those skilled in the art without departing from the concept and scope of the present invention shall fall within the scope of protection of the present invention.

Claims

1. The use of modified fly ash in adsorbing methylene blue, characterized in that, The fly ash modification method is: crushing rotten biomass raw material and adding appropriate amount of water for fermentation treatment; the obtained fermentation acid supernatant is subjected to fermentation bacteria broken wall filtration and evaporation concentration treatment to obtain a biological acid concentrate; the fly ash is mixed with the biological acid concentrate, activated, and the activated fly ash is washed and dried.

2. Use according to claim 1, characterized in that, The rotten biomass is one or more of rotten vegetables, rotten fruits and rotten hyperaccumulator plants.

3. Use according to claim 1, characterized in that, The ratio of the broken rotten biomass slurry to the added water is (0.1-10):

1.

4. The use according to claim 1, characterized in that The fermentation temperature is 50-80℃, and the time is 1-720h.

5. The use according to claim 1, characterized in that, The fermentation bacteria in the supernatant after fermentation of the rotten biomass are subjected to broken wall treatment by microwave pyrolysis, the microwave broken wall power is 10-1000w, and the time is 1-100min.

6. The use according to claim 1, characterized in that, The fermentation acid supernatant after broken wall filtration is subjected to evaporation concentration treatment; the evaporation concentration temperature is 40-110℃, and the time is 1-24h.

7. The use according to claim 1, characterized in that, The mass ratio of the biological acid concentrate to the fly ash is (30-60):

1.

8. The use according to claim 1, characterized in that The activation temperature is 60-80℃, and the activation time is 1-48h.

9. The use according to claim 1, characterized in that, The activated fly ash is washed with deionized water until the water after washing and filtration is neutral, and finally the filtered fly ash is dried in an oven; the drying temperature is 100-110℃, and the time is 24-48h.

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