Monodisperse uniform medicament for adsorbing heavy metal ions in circulating water of coal-fired power plant, preparation method and application thereof

Abstract

The application provides a monodisperse uniform medicament for adsorbing heavy metal ions in circulating water of a coal-fired power plant and a preparation method and application thereof, the medicament takes ferroferric oxide as a core, sodium polyacrylate as a agglomeration inhibitor, modified fly ash as an adsorbent, and polyvinyl alcohol as a nanoparticle connecting agent, and is prepared by using a secondary hydrothermal reaction-secondary emulsion polymerization method; the mass percentage content of the sodium polyacrylate is 20%-40% based on the mass of the ferroferric oxide, the mass percentage content of the modified fly ash is 60%-80%, and the mass percentage content of the polyvinyl alcohol is 10%-20%. In this way, the dispersity and stability of the medicament are improved, and the adsorption effect on the heavy metal ions is improved.

Description

Technical Field

[0001] This application relates to the fields of environmental protection materials and coal-fired power plants, specifically to a monodisperse homogeneous reagent for adsorbing heavy metal ions in circulating water of coal-fired power plants, its preparation method, and its application. Background Technology

[0002] Fly ash is the main solid waste emitted by coal-fired power plants, mainly derived from the ash produced after coal combustion. With the growth of global energy demand, the number and scale of coal-fired power plants have been expanding, leading to a year-on-year increase in fly ash production. China is the world's largest coal producer and consumer, and its fly ash production ranks among the world's top. In 2022, China's fly ash production exceeded 800 million tons. If large amounts of fly ash are not properly disposed of, they will cause serious environmental problems: (1) the storage of fly ash requires a large amount of land resources, resulting in a waste of land resources; (2) fly ash contains some heavy metal elements, which will cause pollution if they seep into water bodies or soil; (3) fly ash is prone to generating dust during storage and transportation, polluting the atmospheric environment. Currently, the main ways to utilize fly ash as a resource include: (1) in the building materials field, fly ash can be used as a raw material or admixture for building materials such as cement, concrete, bricks, and tiles; (2) in road engineering, fly ash can be used for roadbed filling, road base and subbase; (3) in the agricultural field, fly ash can improve soil and increase soil fertility; and (4) recycling, some valuable elements in fly ash, such as alumina and iron oxide, can be extracted and recycled. However, the added value of products made through the above-mentioned resource utilization methods is relatively low. Therefore, research on high-value-added resource utilization of fly ash has important practical significance and environmental benefits.

[0003] On the other hand, the circulating cooling water system of a coal-fired power plant is a crucial link in ensuring the safe and stable operation of the unit. In this system, the cooling water is in contact with the external environment and is easily affected by various pollutants, among which heavy metal ion pollution is particularly prominent and harmful. Heavy metal ions accelerate the corrosion of metal materials in the circulating water system, reduce equipment lifespan, and even cause equipment failure. Discharge of circulating water containing heavy metal ions pollutes the aquatic environment, threatening aquatic life and human health. To ensure the safe and stable operation of the circulating water system and protect the environment and human health, coal-fired power plants must take effective measures to remove heavy metal ions from the circulating water. Currently, the main technologies for removing heavy metal ions from circulating water in coal-fired power plants include: chemical precipitation, adsorption, ion exchange, and membrane separation. Among these methods, adsorption has significant advantages due to its reusability, high adsorption efficiency, and low cost. However, the nanoparticles in conventional adsorption reagents tend to aggregate, leading to a significant reduction in the number of active sites capable of adsorbing heavy metal ions. While monodisperse reagents can maximize the utilization of active sites for heavy metal ion adsorption, they are usually in liquid form, which not only affects storage and transportation but also the dispersing solvent can influence the heavy metal ion adsorption effect. Therefore, developing highly efficient and low-cost monodisperse homogenized heavy metal ion adsorption reagents is crucial for the utilization of circulating water in coal-fired power plants. Summary of the Invention

[0004] This application aims to at least partially address one of the technical problems in the related art.

[0005] The first aspect of this application provides a monodisperse homogeneous agent for adsorbing heavy metal ions in circulating water of coal-fired power plants. The agent has iron oxide as the core, sodium polyacrylate as the agglomeration inhibitor, modified fly ash as the adsorbent, and polyvinyl alcohol as the nanoparticle linker. It is prepared by a two-stage hydrothermal reaction-two-stage emulsion polymerization method.

[0006] Based on the mass of the iron oxide, the mass percentage of the sodium polyacrylate is 20%-40%, the mass percentage of the modified fly ash is 60%-80%, and the mass percentage of the polyvinyl alcohol is 10%-20%.

[0007] The monodisperse homogeneous reagent proposed in this application for adsorbing heavy metal ions in circulating water has a stable structure, good dispersion effect, and can efficiently adsorb heavy metal ions in water.

[0008] The second aspect of this application provides a method for preparing the heavy metal adsorbent provided in the first aspect of this application, the method comprising: S10: Preparation of sodium polyacrylate iron oxide nanospheres: Ferrous salts (Fe2O3) and Fe3O3 are weighed and dissolved in deionized water. Sodium hydroxide solution is added dropwise during low-temperature water bath stirring. When the pH of the solution is neutral, sodium acrylate is added. The mixed slurry is then placed in a hydrothermal reactor for a first hydrothermal reaction. After the first hydrothermal reaction, the mixed slurry is placed in a beaker and a first initiator is added. Nitrogen gas is then introduced into the beaker and a first water bath heating is performed to initiate the polymerization of the sodium acrylate. After the reaction, the mixture is filtered and subjected to a first drying to obtain sodium polyacrylate iron oxide nanosphere powder; S20: Preparation of the reagent: Fly ash is weighed, ground, and sieved. It is then mixed with dilute hydrochloric acid solution and soaked for 4-8 hours, filtered, and subjected to a second drying. The powder obtained after the second drying is then... Modified fly ash is obtained by soaking the fly ash in sodium hydroxide solution for 4-8 hours, filtering and drying. The modified fly ash, morphology control agent, deionized water and the sodium polyacrylate iron oxide nanosphere powder obtained in step S10 are weighed, mixed evenly and placed in a hydrothermal reactor for a second hydrothermal reaction. After the second hydrothermal reaction, the fly ash is filtered and dried to obtain modified fly ash-coated sodium polyacrylate iron oxide nanospheres. Then, vinyl acetate is weighed, dissolved in methanol, and the modified fly ash-coated sodium polyacrylate iron oxide nanospheres are added and stirred evenly. A second initiator is added to the mixed slurry, nitrogen gas is introduced into the mixed slurry and the mixed slurry is heated in a water bath for a second time to initiate the polymerization of vinyl acetate. After the polymerization reaction is completed, sodium hydroxide solution is added and a third water bath heating is carried out to cause the generated polyvinyl acetate to alcoholyze to generate polyvinyl alcohol. After the third water bath heating is completed, the agent is filtered and dried to obtain the reagent.

[0009] According to some embodiments of this application, the ferrous salt mentioned in step S10 is ferrous nitrate or ferrous chloride, and the ferric salt is ferric nitrate nonahydrate or ferric chloride hexahydrate, with a molar ratio of ferrous salt to ferric salt of 1:2.

[0010] According to some embodiments of this application, the mass ratio of ferrous salt to deionized water in step S10 is 1:(60-80), the temperature of the low-temperature water bath is 0-5℃, and the mass concentration of the sodium hydroxide solution is 1mg / mL-2mg / mL.

[0011] According to some embodiments of this application, the temperature of the first hydrothermal reaction in step S10 is 140℃-160℃, the time of the first hydrothermal reaction is 2h-4h, the temperature of the first drying is 40℃-60℃, and the time of the first drying is 12h-24h.

[0012] According to some embodiments of this application, the first initiator in step S10 includes potassium persulfate or ammonium persulfate, the mass ratio of sodium acrylate to the first initiator is 1:(0.05-0.1), the nitrogen gas is introduced at a rate of 20 mL / min-40 mL / min, the temperature of the first water bath heating is 40℃-60℃, and the time of the first water bath heating is 8h-16h.

[0013] According to some embodiments of this application, the metal sieve used for sieving in step S20 has a mesh size of 200-300 mesh, the dilute hydrochloric acid solution is a hydrochloric acid aqueous solution with a mass fraction of 7%-10%, and the sodium hydroxide solution is a sodium hydroxide aqueous solution with a mass concentration of 1mg / mL-5mg / mL.

[0014] According to some embodiments of this application, the mass ratio of fly ash to dilute hydrochloric acid solution in step S20 is 1:(50-100), the mass ratio of powder after the second drying to sodium hydroxide solution is 1:(50-100), the temperature of the second drying is 80℃-100℃, and the time of the second drying is 3h-6h.

[0015] According to some embodiments of this application, the morphology control agent in step S20 includes sodium alginate or potassium alginate, and the mass ratio of the modified fly ash, the morphology control agent, and the deionized water is 1:(0.05-0.2):(40-60).

[0016] According to some embodiments of this application, the temperature of the second hydrothermal reaction in step S20 is 160°C-180°C, and the time of the second hydrothermal reaction is 12h-24h.

[0017] According to some embodiments of this application, the second initiator in step S20 includes benzoyl peroxide or azobisisobutyronitrile, and the mass ratio of the vinyl acetate, the methanol and the second initiator is 1:(30-50):(0.1-0.2).

[0018] According to some embodiments of this application, the nitrogen gas introduction rate in step S20 is 20 mL / min-40 mL / min, the temperature of the second water bath heating is 40℃-60℃, and the time of the second water bath heating is 6h-12h.

[0019] According to some embodiments of this application, the mass ratio of vinyl acetate to sodium hydroxide solution in step S20 is 1:(10-20), the temperature of the third water bath heating is 40℃-60℃, and the time of the third water bath heating is 12h-24h.

[0020] The third aspect of this application provides the application of the reagents provided in the first aspect of this application in the adsorption of heavy metal ions in the circulating water of coal-fired power plants.

[0021] According to some embodiments of this application, the heavy metal ions include Zn. 2+ Cr 3+ At least one of them. Attached Figure Description

[0022] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0023] Figure 1 A schematic flowchart of a method for preparing a pharmaceutical agent according to an embodiment of this application is shown.

[0024] Figure 2 The image shown is an FE-SEM image of the pharmaceutical preparation prepared in Example 1 of this application. Detailed Implementation

[0025] The embodiments of this application are described in detail below. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed in accordance with the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0026] The first aspect of this application provides a monodisperse homogeneous agent for adsorbing heavy metal ions in circulating water of coal-fired power plants. The agent has iron oxide as the core, sodium polyacrylate as the agglomeration inhibitor, modified fly ash as the adsorbent, and polyvinyl alcohol as the nanoparticle linker. It is prepared by a two-stage hydrothermal reaction-two-stage emulsion polymerization method.

[0027] Based on the mass of the iron oxide, the mass percentage of the sodium polyacrylate is 20%-40%, the mass percentage of the modified fly ash is 60%-80%, and the mass percentage of the polyvinyl alcohol is 10%-20%.

[0028] The reagent prepared in this application can achieve efficient adsorption of heavy metal ions in circulating water of coal-fired power plants at room temperature and pressure, thereby realizing high-value-added resource utilization of fly ash and efficient purification of circulating water in coal-fired power plants. Compared with the prior art, this reagent uses magnetic iron oxide as its core, which can easily separate the reagent from the solution after adsorbing heavy metal ions using magnetic separation, which is beneficial to the recycling of the reagent; sodium polyacrylate, as an agglomeration inhibitor, can be adsorbed on the surface of iron oxide nanoparticles to form a stable protective layer, preventing the iron oxide nanoparticles from agglomerating in subsequent preparation and application processes, and improving their dispersibility and stability. Meanwhile, the carboxyl groups of sodium polyacrylate can complex with the hydroxyl groups on the surface of iron oxide nanoparticles, enhancing the binding force between the two and improving the stability of the adsorbent. After acid and alkali washing modification, fly ash removes its impurity ions and, with the promotion of sodium alginate / potassium alginate, grows on the surface of sodium polyacrylate iron oxide nanospheres by hydrothermal method, forming a spherical sandwich structure of iron oxide-sodium polyacrylate-modified fly ash.

[0029] This study fully utilizes the high specific surface area of ​​modified fly ash and the carboxyl functional groups of sodium polyacrylate to adsorb heavy metal ions during the adsorption process. Finally, to prevent the agglomeration of modified fly ash-coated sodium polyacrylate (Fe3O4) nanospheres during transportation and use, which would reduce the number of heavy metal ion adsorption sites, a polyvinyl alcohol (PVA) film is generated on the surface of the fly ash-coated PPA nanospheres through vinyl acetate polymerization-alcoholization. The PPA molecules connect to maintain the monodisperse and uniform structure of the fly ash-coated PPA nanosphere powder after drying, reducing the transportation and maintenance costs of the adsorbent. Furthermore, this reagent is environmentally friendly, has a simple preparation process, low cost, and high cost-effectiveness, making it highly valuable for application and promotion.

[0030] As an example, based on the mass of the iron oxide, the mass percentage of sodium polyacrylate can be 20%, 25%, 30%, 35%, 40%, etc., or can be a range of any of the above values.

[0031] As an example, based on the mass of the iron oxide, the mass percentage of the modified fly ash can be 60%, 65%, 70%, 75%, 80%, etc., or can be a range of any of the above values.

[0032] As an example, based on the mass of the iron oxide, the mass percentage of the polyvinyl alcohol can be 10%, 12%, 14%, 16%, 18%, 20%, etc., or can be a range of any of the above values.

[0033] The second aspect of this application provides a method for preparing the heavy metal adsorbent provided in the first aspect of this application. The method includes: S10: Preparation of sodium polyacrylate iron oxide nanospheres: Ferrous divalent and ferric trivalent salts are weighed and dissolved in deionized water. Sodium hydroxide solution is added dropwise during low-temperature water bath stirring. When the pH of the solution is neutral, sodium acrylate is added. The mixed slurry is then placed in a hydrothermal reactor for a first hydrothermal reaction. After the first hydrothermal reaction, the mixed slurry is placed in a beaker and a first initiator is added. Nitrogen gas is then introduced into the beaker and a first water bath heating is performed to initiate the polymerization of the sodium acrylate. After the reaction, the mixture is filtered and dried for the first time to obtain sodium polyacrylate iron oxide nanosphere powder; S20: Preparation of the reagent: Fly ash is weighed, ground, and sieved. It is then mixed with dilute hydrochloric acid solution and soaked for 4-8 hours, filtered, and dried a second time. The powder after the second drying is then... Modified fly ash is obtained by soaking the fly ash in sodium hydroxide solution for 4-8 hours, filtering and drying. The modified fly ash, morphology control agent, deionized water and the sodium polyacrylate iron oxide nanosphere powder obtained in step S10 are weighed, mixed evenly and placed in a hydrothermal reactor for a second hydrothermal reaction. After the second hydrothermal reaction, the fly ash is filtered and dried to obtain modified fly ash-coated sodium polyacrylate iron oxide nanospheres. Then, vinyl acetate is weighed, dissolved in methanol, and the modified fly ash-coated sodium polyacrylate iron oxide nanospheres are added and stirred evenly. A second initiator is added to the mixed slurry, nitrogen gas is introduced into the mixed slurry and the mixed slurry is heated in a water bath for a second time to initiate the polymerization of vinyl acetate. After the polymerization reaction is completed, sodium hydroxide solution is added and a third water bath heating is carried out to cause the generated polyvinyl acetate to alcoholyze to generate polyvinyl alcohol. After the third water bath heating is completed, the agent is filtered and dried to obtain the reagent.

[0034] The method proposed in this application is described in detail below, for reference only. Figure 1 The method includes:

[0035] S10: Preparation of sodium polyacrylate iron oxide nanospheres

[0036] In this step, ferrous salts (Fe2+ and Fe3+) are weighed and dissolved in deionized water. Sodium hydroxide solution is added dropwise while stirring in a low-temperature water bath. When the pH of the solution is neutral, sodium acrylate is added. The mixed slurry is then placed in a hydrothermal reactor for the first hydrothermal reaction. After the first hydrothermal reaction, the mixed slurry is placed in a beaker and a first initiator is added. Nitrogen gas is then introduced into the beaker and a first water bath heating is performed to initiate the polymerization of sodium acrylate. After the reaction, the mixture is filtered and dried for the first time to obtain sodium polyacrylate iron tetroxide nanosphere powder.

[0037] According to some embodiments of this application, the divalent ferric salt is ferrous nitrate or ferrous chloride, the trivalent ferric salt is ferric nitrate nonahydrate or ferric chloride hexahydrate, and the molar ratio of the divalent ferric salt to the trivalent ferric salt is 1:2.

[0038] According to some embodiments of this application, the mass ratio of the divalent iron salt to deionized water is 1:(60-80), for example, it can be 1:60, 1:70, 1:80, etc., or it can be any range of the above values.

[0039] According to some embodiments of this application, the temperature of the low-temperature water bath is 0℃-5℃, and the mass concentration of the sodium hydroxide solution is 1mg / mL-2mg / mL.

[0040] As an example, the temperature of the low-temperature water body can be 0℃, 2℃, 4℃, 5℃, etc., or can be a range of any of the above values.

[0041] As an example, the mass concentration of the sodium hydroxide solution can be 1 mg / mL, 1.2 mg / mL, 1.4 mg / mL, 1.6 mg / mL, 1.8 mg / mL, 2 mg / mL, etc., or can be a range of any of the above values.

[0042] According to some embodiments of this application, the temperature of the first hydrothermal reaction is 140℃-160℃, and the time of the first hydrothermal reaction is 2h-4h.

[0043] As an example, the temperature of the first hydrothermal reaction can be 140℃, 150℃, 160℃, etc., or can be any range of the above values.

[0044] As an example, the time for the first hydrothermal reaction can be 2h, 3h, 4h, etc., or can be any range of the above values.

[0045] According to some embodiments of this application, the temperature of the first drying is 40℃-60℃, and the time of the first drying is 12h-24h.

[0046] As an example, the temperature for the first drying step can be 40℃, 50℃, 60℃, or any range of the above values. The drying time for the first drying step can be 12h, 16h, 20h, 24h, or any range of the above values.

[0047] According to some embodiments of this application, the first initiator includes potassium persulfate or ammonium persulfate, and the mass ratio of sodium acrylate to the first initiator is 1:(0.05-0.1).

[0048] As an example, the mass ratio of sodium acrylate to the first initiator can be 1:0.05, 1:0.07, 1:0.09, 1:0.1, or any range of the above values.

[0049] According to some embodiments of this application, the nitrogen gas introduction rate is 20 mL / min-40 mL / min, the temperature of the first water bath heating is 40℃-60℃, and the time of the first water bath heating is 8h-16h.

[0050] S20: Preparation of the pharmaceutical preparation

[0051] In this step, fly ash is weighed, ground, and sieved. It is then mixed with dilute hydrochloric acid solution and soaked for 4-8 hours, filtered, and dried a second time. The dried powder is then mixed with sodium hydroxide solution and soaked for 4-8 hours, filtered, and dried to obtain modified fly ash. The modified fly ash, morphology control agent, deionized water, and the sodium polyacrylate (Fe3O4) nanosphere powder obtained in step S10 are weighed, mixed evenly, and placed in a hydrothermal reactor for a second hydrothermal reaction. After the second hydrothermal reaction, the mixture is filtered and dried to obtain modified fly ash-coated sodium polyacrylate (Fe3O4) nanospheres. Vinyl acetate is then weighed, dissolved in methanol, and the modified fly ash-coated sodium polyacrylate (Fe3O4) nanospheres are added and stirred evenly. A second initiator is added to the mixed slurry, nitrogen gas is introduced into the slurry, and the slurry is heated in a water bath to initiate the polymerization of vinyl acetate. After the polymerization reaction, sodium hydroxide solution is added, and a third water bath heating is performed to cause the generated vinyl acetate to undergo alcoholysis to generate polyvinyl alcohol. After the third water bath heating, the mixture is filtered and dried to obtain the reagent.

[0052] According to some embodiments of this application, the metal sieve used for sieving has a mesh size of 200-300 mesh. This reduces the particle size of the fly ash and increases the contact area between the fly ash and acid and alkaline solutions.

[0053] According to some embodiments of this application, the dilute hydrochloric acid solution is a hydrochloric acid aqueous solution with a mass fraction of 7%-10%, for example, it can be 7%, 8%, 9%, 10%, etc., or it can be any range of the above values.

[0054] According to some embodiments of this application, the sodium hydroxide solution is an aqueous solution of sodium hydroxide with a mass concentration of 1 mg / mL to 5 mg / mL. For example, it can be 1 mg / mL, 2 mg / mL, 3 mg / mL, 4 mg / mL, 5 mg / mL, etc., or it can be any range of the above values.

[0055] According to some embodiments of this application, the mass ratio of the fly ash to the dilute hydrochloric acid solution is 1:(50-100), for example, it can be 1:50, 1:65, 1:80, 1:100, etc., or it can be any range of the above values.

[0056] According to some embodiments of this application, the mass ratio of the dried powder to the sodium hydroxide solution is 1:(50-100), for example, it can be 1:50, 1:65, 1:80, 1:100, etc., or it can be any range of the above values.

[0057] According to some embodiments of this application, the temperature of the second drying is 80℃-100℃, and the time of the second drying is 3h-6h.

[0058] According to some embodiments of this application, the morphology control agent includes sodium alginate or potassium alginate, and the mass ratio of the modified fly ash, the morphology control agent, and the deionized water is 1:(0.05-0.2):(40-60).

[0059] Nanospheres were obtained by adding morphology control agents.

[0060] According to some embodiments of this application, the temperature of the second hydrothermal reaction is 160℃-180℃, and the time of the second hydrothermal reaction is 12h-24h.

[0061] According to some embodiments of this application, the second initiator includes benzoyl peroxide or azobisisobutyronitrile, and the mass ratio of the vinyl acetate, the methanol and the second initiator is 1:(30-50):(0.1-0.2).

[0062] As an example, the mass ratio of the vinyl acetate, the methanol, and the second initiator can be...

[0063] According to some embodiments of this application, the nitrogen gas introduction rate is 20 mL / min-40 mL / min.

[0064] According to some embodiments of this application, the temperature of the second water bath heating is 40℃-60℃, and the time of the second water bath heating is 6h-12h.

[0065] According to some embodiments of this application, the mass ratio of vinyl acetate to sodium hydroxide solution is 1:(10-20). For example, it can be 1:10, 1:12, 1:14, 1:16, 1:18, 1:20, etc., or it can be any range of the above values.

[0066] According to some embodiments of this application, the temperature of the third water bath heating is 40℃-60℃, and the time of the third water bath heating is 12h-24h.

[0067] The third aspect of this application provides the application of the reagents provided in the first aspect of this application in the adsorption of heavy metal ions in the circulating water of coal-fired power plants.

[0068] According to some embodiments of this application, the heavy metal ions include Zn. 2+ Cr 3+ At least one of them.

[0069] The embodiments of this application are described in detail below. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed in accordance with the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0070] Example 1

[0071] S10: Preparation of sodium polyacrylate iron oxide nanospheres

[0072] 3.597 g of ferrous nitrate and 16.160 g of ferric nitrate nonahydrate were weighed and dissolved in 215.82 g of deionized water. Sodium hydroxide solution with a mass concentration of 1 mg / mL was added dropwise while stirring in a water bath at 0 °C. When the pH of the solution was neutral, 0.926 g of sodium acrylate was added. The mixture was then placed in a hydrothermal reactor and hydrothermally reacted at 140 °C for 4 h. After the hydrothermal reaction was completed, the mixture was placed in a beaker and 46 mg of potassium persulfate was added. Nitrogen gas was then introduced into the beaker (nitrogen gas rate of 20 mL / min) and the mixture was heated in a water bath at 40 °C for 16 h to initiate the polymerization of sodium acrylate. After the reaction was completed, the mixture was filtered and dried at 40 °C for 24 h to obtain sodium polyacrylate iron oxide nanosphere powder.

[0073] S20: Pharmaceutical Preparation

[0074] 20g of fly ash was weighed, ground, and sieved to obtain fly ash powder with a particle size of 48μm to 75μm. This powder was then mixed with 1000g of 7% hydrochloric acid solution and soaked for 8 hours, filtered, and dried at 80℃ for 6 hours. The dried powder was then mixed with 1000g of 1mg / mL sodium hydroxide solution and soaked for 8 hours, filtered, and dried at 80℃ for 6 hours to obtain modified fly ash. 2.779g of modified fly ash, 0.139g of sodium alginate, 111.160g of deionized water, and the sodium polyacrylate (Fe3O4) nanosphere powder obtained in step S10 were weighed, mixed evenly, and placed in a hydrothermal reactor for hydrothermal reaction at 160℃ for 24 hours. After the hydrothermal reaction, the mixture was filtered and dried at 80℃ for 6 hours to obtain modified fly ash-coated sodium polyacrylate (Fe3O4) nanospheres. Then, 0.908g of vinyl acetate was weighed and dissolved in 2... 7.240g of methanol was mixed with the prepared modified fly ash-coated sodium polyacrylate (Fe3O4) nanospheres, and stirred until homogeneous. Then, 0.091g of benzoyl peroxide was added to the mixture, followed by nitrogen gas (20mL / min) being introduced. The mixture was then heated in a 40℃ water bath for 12 hours to initiate the polymerization of vinyl acetate. After polymerization, 9.080g of a 1mg / mL sodium hydroxide solution was added, and the mixture was heated in a 40℃ water bath for another 24 hours to allow the generated polyvinyl acetate to undergo alcoholysis to produce polyvinyl alcohol. After the water bath heating was completed, the mixture was filtered and dried at 80℃ for 6 hours to obtain the reagent (based on the mass of the Fe3O4 core, the mass percentage of sodium polyacrylate is 20%, the mass percentage of modified fly ash is 60%, and the mass percentage of polyvinyl alcohol is 10%). The FE-SEM image of the reagent is attached. Figure 2 As shown.

[0075] Example 2

[0076] S10: Preparation of sodium polyacrylate iron oxide nanospheres

[0077] 2.535 g of ferrous chloride and 10.812 g of ferric chloride hexahydrate were weighed and dissolved in 215.82 g of deionized water. Sodium hydroxide solution with a mass concentration of 2 mg / mL was added dropwise while stirring in a water bath at 5 °C. When the pH of the solution was neutral, 1.852 g of sodium acrylate was added. The mixed slurry was then placed in a hydrothermal reactor and hydrothermally reacted at 160 °C for 2 h. After the hydrothermal reaction was completed, the mixed slurry was placed in a beaker and 0.185 g of ammonium persulfate was added. Nitrogen gas was then introduced into the beaker (nitrogen gas rate of 40 mL / min) and heated in a water bath at 60 °C for 8 h to initiate the polymerization of sodium acrylate. After the reaction was completed, the mixture was filtered and dried at 60 °C for 12 h to obtain sodium polyacrylate iron oxide nanosphere powder.

[0078] S20: Preparation of the pharmaceutical preparation

[0079] 20g of fly ash was weighed, ground, and sieved to obtain fly ash powder with a particle size of 48μm to 75μm. This powder was then mixed with 2000g of 10% hydrochloric acid solution and soaked for 4 hours. After filtration, the powder was dried at 100℃ for 3 hours. The dried powder was then mixed with 2000g of 5mg / mL sodium hydroxide solution and soaked for 4 hours. After filtration and drying at 100℃ for 3 hours, modified fly ash was obtained. 3.705g of modified fly ash, 0.741g of potassium alginate, 222.300g of deionized water, and the sodium polyacrylate (Fe3O4) nanosphere powder obtained in step S10 were weighed, mixed evenly, and placed in a hydrothermal reactor for hydrothermal reaction at 180℃ for 12 hours. After the hydrothermal reaction, the mixture was filtered and dried at 100℃ for 3 hours to obtain modified fly ash-coated sodium polyacrylate (Fe3O4) nanospheres. Then, 1.816g of vinyl acetate was weighed and dissolved... Add the prepared modified fly ash-coated sodium polyacrylate (Fe3O4) nanospheres to 90.800 g of methanol and stir until homogeneous. Then add 0.363 g of azobisisobutyronitrile (AIBN) to the mixture. Purge the mixture with nitrogen gas (at a rate of 40 mL / min) and heat it in a 60°C water bath for 6 h to initiate the polymerization of vinyl acetate. After the polymerization reaction is complete, add 36.320 g of sodium hydroxide solution with a mass concentration of 5 mg / mL and continue heating in a 60°C water bath for 12 h to allow the generated polyvinyl acetate to undergo alcoholysis to generate polyvinyl alcohol. After the water bath heating is completed, filter and dry at 100°C for 3 h to obtain the reagent (based on the mass of the Fe3O4 core, the mass percentage of sodium polyacrylate is 40%, the mass percentage of modified fly ash is 80%, and the mass percentage of polyvinyl alcohol is 20%).

[0080] Performance testing

[0081] Adsorption effect of heavy metal ions

[0082] 1g of the reagents from Examples 1 and 2 were placed in 1000mL of a heavy metal ion solution with a concentration of CrCl3 (1mg / mL). After the reagents were adsorbed for 30min at room temperature and pressure, the concentration of heavy metal ions in the heavy metal ion solution before and after adsorption was determined by inductively coupled plasma spectroscopy.

[0083] The test results for Examples 1 and 2 are shown in Table 1.

[0084] Table 1

[0085]

[0086] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0087] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A monodisperse homogeneous reagent for adsorbing heavy metal ions in circulating water of coal-fired power plants, characterized in that, The agent is prepared using a two-stage hydrothermal reaction-two-stage emulsion polymerization method with iron oxide as the core, sodium polyacrylate as the agglomeration inhibitor, modified fly ash as the adsorbent, and polyvinyl alcohol as the nanoparticle linker. Based on the mass of the iron oxide, the mass percentage of the sodium polyacrylate is 20%-40%, the mass percentage of the modified fly ash is 60%-80%, and the mass percentage of the polyvinyl alcohol is 10%-20%.

2. A method for preparing the pharmaceutical agent according to claim 1, characterized in that, include: S10: Preparation of sodium polyacrylate iron oxide nanospheres Weigh out ferrous salts and ferric salts and dissolve them in deionized water. Add sodium hydroxide solution dropwise while stirring in a low-temperature water bath. When the pH of the solution is neutral, add sodium acrylate. Then place the mixed slurry in a hydrothermal reactor for the first hydrothermal reaction. After the first hydrothermal reaction, place the mixed slurry in a beaker and add the first initiator. Then, purge the beaker with nitrogen and heat it in a water bath for the first time to initiate the polymerization of sodium acrylate. After the reaction, filter and perform the first drying to obtain sodium polyacrylate iron tetroxide nanosphere powder. S20: Preparation of the pharmaceutical preparation Weigh fly ash, grind and sieve it, then mix it with dilute hydrochloric acid solution and soak for 4-8 hours, filter and dry it a second time. The dried powder is then mixed with sodium hydroxide solution and soaked for 4-8 hours, filtered and dried to obtain modified fly ash. Weigh the modified fly ash, morphology control agent, deionized water and the sodium polyacrylate (Fe3O4) nanosphere powder obtained in step S10, mix them evenly and place them in a hydrothermal reactor for a second hydrothermal reaction. After the second hydrothermal reaction, filter and dry to obtain modified fly ash-coated sodium polyacrylate (Fe3O4) nanospheres. Then weigh vinyl acetate, dissolve it in methanol, add the modified fly ash-coated sodium polyacrylate (Fe3O4) nanospheres and stir evenly. Add a second initiator to the mixed slurry, then introduce nitrogen gas into the mixed slurry and subject it to a second water bath heating to initiate vinyl acetate polymerization. After the polymerization reaction, add sodium hydroxide solution and perform a third water bath heating to cause the generated vinyl acetate to alcoholyze to produce polyvinyl alcohol. After the third water bath heating, filter and dry to obtain the reagent.

3. The method according to claim 2, characterized in that, The ferrous salt mentioned in step S10 is ferrous nitrate or ferrous chloride, and the ferric salt is ferric nitrate nonahydrate or ferric chloride hexahydrate. The molar ratio of ferrous salt to ferric salt is 1:

2.

4. The method according to claim 2, characterized in that, In step S10, the mass ratio of ferrous salt to deionized water is 1:(60-80), the temperature of the low-temperature water bath is 0℃-5℃, and the mass concentration of sodium hydroxide solution is 1mg / mL-2mg / mL.

5. The method according to claim 2, characterized in that, In step S10, the temperature of the first hydrothermal reaction is 140℃-160℃, the time of the first hydrothermal reaction is 2h-4h, the temperature of the first drying is 40℃-60℃, and the time of the first drying is 12h-24h.

6. The preparation method according to claim 2, characterized in that, The first initiator in step S10 includes potassium persulfate or ammonium persulfate, the mass ratio of sodium acrylate to the first initiator is 1:(0.05-0.1), the nitrogen gas is introduced at a rate of 20 mL / min-40 mL / min, the temperature of the first water bath heating is 40℃-60℃, and the time of the first water bath heating is 8h-16h.

7. The preparation method according to claim 2, characterized in that, In step S20, the metal sieve used for sieving has a mesh size of 200-300 mesh, the dilute hydrochloric acid solution is a hydrochloric acid aqueous solution with a mass fraction of 7%-10%, and the sodium hydroxide solution is a sodium hydroxide aqueous solution with a mass concentration of 1mg / mL-5mg / mL.

8. The preparation method according to claim 2, characterized in that, In step S20, the mass ratio of fly ash to dilute hydrochloric acid solution is 1:(50-100), the mass ratio of powder after the second drying to sodium hydroxide solution is 1:(50-100), the temperature of the second drying is 80℃-100℃, and the time of the second drying is 3h-6h.

9. The preparation method according to claim 2, characterized in that, The morphology control agent in step S20 includes sodium alginate or potassium alginate, and the mass ratio of the modified fly ash, the morphology control agent, and the deionized water is 1:(0.05-0.2):(40-60).

10. The preparation method according to claim 2, characterized in that, The temperature of the second hydrothermal reaction in step S20 is 160℃-180℃, and the time of the second hydrothermal reaction is 12h-24h.

11. The preparation method according to claim 2, characterized in that, In step S20, the second initiator includes benzoyl peroxide or azobisisobutyronitrile, and the mass ratio of vinyl acetate, methanol and the second initiator is 1:(30-50):(0.1-0.2).

12. The preparation method according to claim 2, characterized in that, In step S20, the nitrogen gas is introduced at a rate of 20 mL / min to 40 mL / min, the temperature of the second water bath heating is 40℃ to 60℃, and the heating time of the second water bath heating is 6h to 12h.

13. The preparation method according to claim 2, characterized in that, In step S20, the mass ratio of vinyl acetate to sodium hydroxide solution is 1:(10-20), the temperature of the third water bath heating is 40℃-60℃, and the time of the third water bath heating is 12h-24h.

14. The application of the reagent according to claim 1 in the adsorption of heavy metal ions in the circulating water of a coal-fired power plant.

15. The application according to claim 14, wherein the heavy metal ions include Zn. 2+ Cr 3+ At least one of them.

Images