Monodisperse homogeneous medicament for adsorbing heavy metal ions in circulating water of coal-fired power plant as well as preparation method and application of monodisperse homogeneous medicament

Abstract

The invention provides a monodisperse homogeneous agent for adsorbing heavy metal ions in circulating water of a coal-fired power plant and a preparation method and application of the monodisperse homogeneous agent. According to the agent, ferroferric oxide serves as an inner core, sodium polyacrylate serves as an agglomeration inhibitor, modified fly ash serves as an adsorbent, and polyvinyl alcohol serves as a nanoparticle connecting agent. A secondary hydrothermal reaction-secondary emulsion polymerization method is adopted for preparation; on the basis of the mass of the ferroferric oxide, the mass percentage content of the sodium polyacrylate is 20%-40%, the mass percentage content of the modified fly ash is 60%-80%, and the mass percentage content of the polyvinyl alcohol is 10%-20%. Therefore, the dispersibility and stability of the medicament are improved, and the adsorption effect on heavy metal ions is improved.

Description

Technical Field

[0001] The present application relates to the field of environmentally friendly materials and coal-fired power plants, and in particular, to a monodisperse uniform agent for adsorbing heavy metal ions in circulating water of a coal-fired power plant, and a preparation method and application thereof. Background Art

[0002] Fly ash is the main solid waste emitted by coal-fired power plants, mainly from the ash produced after coal combustion. With the growth of global energy demand, the number and scale of coal-fired power plants have continued to expand, resulting in an increase in fly ash production year by year. China is the world's largest coal producer and consumer, and its fly ash production is also among the highest in the world. In 2022, China's fly ash production exceeded 800 million tons. If a large amount of fly ash is not properly handled, it 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 or soil; (3) Fly ash is prone to generate dust during storage and transportation, polluting the atmospheric environment. At present, the resource utilization of fly ash mainly includes: (1) in the field of building materials, fly ash can be used as 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, pavement base and subbase, etc.; (3) in the agricultural field, fly ash can improve soil and increase soil fertility; (4) recycling, some valuable elements in fly ash, such as aluminum oxide and iron oxide, can be extracted and recycled. However, the added value of the products made by the above resource utilization methods is relatively low. Therefore, research on the high added value 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 key link to ensure the safe and stable operation of the unit. In the circulating water 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 a more prominent and serious one. Heavy metal ions will accelerate the corrosion of metal materials in the circulating water system, reduce the service life of the equipment, and even cause equipment failure. The discharge of circulating water containing heavy metal ions will pollute the water environment and threaten aquatic life and human health. In order 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. At present, the main technologies for removing heavy metal ions from circulating water in coal-fired power plants include: chemical precipitation, adsorption, ion exchange, membrane separation, etc. Among them, the adsorption method has obvious advantages due to its reusability, high adsorption efficiency and low cost, but the nanoparticles in conventional adsorbents are easy to agglomerate, resulting in a significant reduction in the number of active sites that can adsorb heavy metal ions. Although monodisperse agents can maximize the use of active sites for adsorbing heavy metal ions, they are usually in liquid form, which not only affects storage and transportation, but the dispersed solvent in them also affects the adsorption effect of heavy metal ions. Therefore, the development of high-efficiency and low-cost monodisperse homogenized heavy metal ion adsorbents is the key to the utilization of circulating water in coal-fired power plants. Summary of the invention

[0004] The present application aims to solve one of the technical problems in the related art at least to some extent.

[0005] In a first aspect, the present application provides a monodisperse uniform agent for adsorbing heavy metal ions in circulating water of a coal-fired power plant, wherein the agent has ferroferric oxide as a core, sodium polyacrylate as an agglomeration inhibitor, modified fly ash as an adsorbent, and polyvinyl alcohol as a nanoparticle linker, and is prepared by a secondary hydrothermal reaction-secondary emulsion polymerization method;

[0006] Based on the mass of the ferrosoferric 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 and uniform agent for adsorbing heavy metal ions in circulating water proposed in the present application has a stable structure and good dispersion effect, and can efficiently adsorb heavy metal ions in water.

[0008] The second aspect of the present application provides a method for preparing the heavy metal adsorption agent provided in the first aspect of the present application, the method comprising: S10: Preparation of sodium polyacrylate ferroferric oxide nanospheres: weighing divalent iron salt and trivalent iron salt and dissolving them in deionized water, adding sodium hydroxide solution dropwise during stirring in a low-temperature water bath, adding sodium acrylate when the pH value of the solution is neutral, and then placing the mixed slurry in a hydrothermal reactor for a first hydrothermal reaction, after the first hydrothermal reaction, placing the mixed slurry in a beaker and adding a first initiator, then passing nitrogen into the beaker and performing a first water bath heating to initiate polymerization of the sodium acrylate, filtering after the reaction, and performing a first drying to obtain sodium polyacrylate ferroferric oxide nanosphere powder; S20: Preparation of the agent: weighing fly ash, grinding and sieving, then mixing with a dilute hydrochloric acid solution, soaking for 4h-8h, filtering and performing a second drying, and then the powder after the second drying The modified fly ash is mixed with a sodium hydroxide solution and soaked for 4h-8h, and then filtered and dried to obtain a modified fly ash; the modified fly ash, morphology control agent, deionized water and the sodium polyacrylate ferroferric 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 is completed, the modified fly ash is filtered and dried to obtain the sodium polyacrylate ferroferric oxide nanospheres wrapped with the modified fly ash; then vinyl acetate is weighed and dissolved in methanol, and the modified fly ash is added to the sodium polyacrylate ferroferric oxide nanospheres wrapped with the modified fly ash and stirred evenly; then a second initiator is added to the mixed slurry; then nitrogen 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, a sodium hydroxide solution is added, and the water bath heating is continued for a third time to hydrolyze the generated polyvinyl acetate to generate polyvinyl alcohol; after the third water bath heating is completed, the agent is filtered and dried to obtain the agent.

[0009] According to some embodiments of the present application, the divalent iron salt in step S10 is ferrous nitrate or ferrous chloride, the trivalent iron salt is ferric nitrate nonahydrate or ferric chloride hexahydrate, and the molar ratio of the divalent iron salt to the trivalent iron salt is 1:2.

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

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

[0012] According to some embodiments of the present 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 rate of nitrogen introduction is 20mL / min-40mL / min, the temperature of the first water bath heating is 40°C-60°C, and the time of the first water bath heating is 8h-16h.

[0013] According to some embodiments of the present application, the mesh size of the metal screen used for screening in step S20 is 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 1 mg / mL-5 mg / mL.

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

[0015] According to some embodiments of the present 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 the present 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 12 h-24 h.

[0017] According to some embodiments of the present 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 the present application, the rate of introducing nitrogen in step S20 is 20 mL / min-40 mL / min, the temperature of the second water bath heating is 40° C.-60° C., and the time of the second water bath heating is 6 h-12 h.

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

[0020] The third aspect of the present application provides the use of the agent provided in the first aspect of the present application in adsorbing heavy metal ions in circulating water of a coal-fired power plant.

[0021] According to some embodiments of the present application, the heavy metal ions include Zn 2+ Cr 3+ At least one of . BRIEF DESCRIPTION OF THE DRAWINGS

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

[0023] Figure 1 A schematic flow chart of a method for preparing a medicament according to an embodiment of the present application is shown.

[0024] Figure 2 The FE-SEM image of the agent prepared in Example 1 of the present application is shown. DETAILED DESCRIPTION

[0025] The embodiments of the present application are described in detail below. The embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. If no specific technology or conditions are indicated in the embodiments, the technology or conditions described in the documents in this area or the product instructions are used. The reagents used or the instruments that do not indicate the manufacturer are all conventional products that can be obtained commercially.

[0026] In a first aspect, the present application provides a monodisperse uniform agent for adsorbing heavy metal ions in circulating water of a coal-fired power plant, wherein the agent has ferroferric oxide as a core, sodium polyacrylate as an agglomeration inhibitor, modified fly ash as an adsorbent, and polyvinyl alcohol as a nanoparticle linker, and is prepared by a secondary hydrothermal reaction-secondary emulsion polymerization method;

[0027] Based on the mass of the ferrosoferric 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 agent prepared in this application can achieve efficient adsorption of heavy metal ions in circulating water of coal-fired power plants at normal temperature and pressure, thereby achieving high value-added resource utilization of fly ash and efficient purification of circulating water of coal-fired power plants. Compared with the prior art, the agent uses magnetic ferroferric oxide as the core, and can easily separate the agent from the solution by magnetic separation after adsorbing heavy metal ions, which is conducive to the recycling of the agent; sodium polyacrylate, as an agglomeration inhibitor, can be adsorbed on the surface of ferroferric oxide nanoparticles to form a stable protective layer, preventing ferroferric oxide nanoparticles from agglomerating in the subsequent preparation process and application process, and improving its dispersibility and stability. At the same time, the carboxyl group of sodium polyacrylate can complex with the hydroxyl group on the surface of ferroferric oxide nanoparticles to enhance the binding force between the two and improve the stability of the adsorbent; the fly ash is modified by acid and alkaline washing to remove its impurity ions, and under the promotion of sodium alginate / potassium alginate, it is grown on the surface of sodium polyacrylate ferroferric oxide nanospheres by hydrothermal method to form a spherical sandwich structure of ferroferric oxide-sodium polyacrylate-modified fly ash.

[0029] In the process of adsorbing heavy metal ions, the high specific surface area of ​​modified fly ash and the carboxyl functional groups of sodium polyacrylate are fully utilized to adsorb heavy metal ions; finally, in order to avoid the agglomeration of modified fly ash-coated sodium polyacrylate ferroferric oxide nanospheres during transportation and use, which will reduce the number of heavy metal ion adsorption sites, vinyl acetate polymerization-alcoholysis is used to generate a polyvinyl alcohol film on the surface of fly ash-coated sodium polyacrylate ferroferric oxide nanospheres, and the connection of polyvinyl alcohol molecules is used to make the powder of fly ash-coated sodium polyacrylate ferroferric oxide nanospheres maintain a monodisperse uniform structure after drying, thereby reducing the transportation and maintenance costs of the adsorption agent; and the agent components are environmentally friendly, simple in preparation process, low in cost, high in cost performance, and have strong application and promotion value.

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

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

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

[0033] The second aspect of the present application provides a method for preparing the heavy metal adsorption agent provided in the first aspect of the present application, the method comprising: S10: Preparation of sodium polyacrylate ferroferric oxide nanospheres: weighing divalent iron salt and trivalent iron salt and dissolving them in deionized water, adding sodium hydroxide solution dropwise during stirring in a low-temperature water bath, adding sodium acrylate when the pH value of the solution is neutral, and then placing the mixed slurry in a hydrothermal reactor for a first hydrothermal reaction, after the first hydrothermal reaction is completed, placing the mixed slurry in a beaker and adding a first initiator, then passing nitrogen into the beaker and performing a first water bath heating to initiate polymerization of the sodium acrylate, filtering after the reaction is completed, and performing a first drying to obtain sodium polyacrylate ferroferric oxide nanosphere powder; S20: Preparation of the agent: weighing fly ash, grinding and sieving, then mixing with a dilute hydrochloric acid solution, soaking for 4h-8h, filtering and performing a second drying, and then the powder after the second drying The modified fly ash is mixed with a sodium hydroxide solution and soaked for 4h-8h, and then filtered and dried to obtain a modified fly ash; the modified fly ash, morphology control agent, deionized water and the sodium polyacrylate ferroferric 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 is completed, the modified fly ash is filtered and dried to obtain the sodium polyacrylate ferroferric oxide nanospheres wrapped with the modified fly ash; then vinyl acetate is weighed and dissolved in methanol, and the modified fly ash is added to the sodium polyacrylate ferroferric oxide nanospheres wrapped with the modified fly ash and stirred evenly; then a second initiator is added to the mixed slurry; then nitrogen 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, a sodium hydroxide solution is added and heated in a water bath for a third time to hydrolyze the generated polyvinyl acetate to generate polyvinyl alcohol; after the third water bath heating is completed, the agent is filtered and dried to obtain the agent.

[0034] The method proposed in this application is described in detail below. Figure 1 , the method comprising:

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

[0036] In this step, a divalent iron salt and a trivalent iron salt are weighed and dissolved in deionized water, and a sodium hydroxide solution is added dropwise during stirring in a low-temperature water bath, and sodium acrylate is added when the pH value of the solution is neutral, and then the mixed slurry is 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, and then nitrogen is introduced into the beaker and a first water bath heating is performed to initiate polymerization of sodium acrylate, and after the reaction is completed, the mixture is filtered and dried for a first time to obtain sodium polyacrylate ferroferric oxide nanosphere powder.

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

[0038] According to some embodiments of the present 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 a range consisting of any of the above numerical values.

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

[0040] As an example, the temperature of the low-temperature water area may be 0°C, 2°C, 4°C, 5°C, etc., or may be a range consisting 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 consisting of any of the above values.

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

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

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

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

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

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

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

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

[0050] S20: Preparation of medicine

[0051] In this step, fly ash is weighed, ground and sieved, and then mixed with a dilute hydrochloric acid solution and soaked for 4h-8h, filtered and dried for a second time, and then the powder after the second drying is mixed with a sodium hydroxide solution and soaked for 4h-8h, filtered and dried to obtain modified fly ash; the modified fly ash, morphology control agent, deionized water and the sodium polyacrylate ferroferric oxide nanosphere powder obtained in step S10 are weighed, mixed evenly and placed in a hydrothermal reactor for a second hydrothermal reaction, and after the second hydrothermal reaction is completed, filtered and dried to obtain modified fly ash-coated sodium polyacrylate ferroferric oxide nanospheres, and then vinyl acetate is weighed and dissolved in methanol, and the modified fly ash-coated sodium polyacrylate ferroferric oxide nanospheres are added and stirred evenly, and then a second initiator is added to the mixed slurry, and then nitrogen is introduced into the mixed slurry and the mixed slurry is heated in a water bath to initiate the polymerization of vinyl acetate, and after the polymerization reaction is completed, sodium hydroxide solution is added, and a third water bath heating is performed to hydrolyze the generated polyvinyl acetate to generate polyvinyl alcohol, and after the third water bath heating is completed, the agent is filtered and dried to obtain the agent.

[0052] According to some embodiments of the present application, the mesh size of the metal screen used for sieving is 200-300 mesh, thereby reducing the particle size of the fly ash and increasing the contact area between the fly ash and the acid solution and the alkaline solution.

[0053] According to some embodiments of the present 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 a range composed of any of the above numerical values.

[0054] According to some embodiments of the present application, the sodium hydroxide solution is a sodium hydroxide aqueous solution with a mass concentration of 1 mg / mL-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 can be a range composed of any of the above values.

[0055] According to some embodiments of the present 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 a range consisting of any of the above numerical values.

[0056] According to some embodiments of the present 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 a range consisting of any of the above numerical values.

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

[0058] According to some embodiments of the present 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 are obtained by adding morphology control agents.

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

[0061] According to some embodiments of the present 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 the present application, the rate of introducing nitrogen is 20 mL / min-40 mL / min.

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

[0065] According to some embodiments of the present application, the mass ratio of the vinyl acetate to the 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 can be a range consisting of any of the above values.

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

[0067] The third aspect of the present application provides the use of the agent provided in the first aspect of the present application in adsorbing heavy metal ions in circulating water of a coal-fired power plant.

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

[0069] The embodiments of the present application are described in detail below. The embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. If no specific technology or conditions are indicated in the embodiments, the technology or conditions described in the documents in this area or the product instructions are used. The reagents used or the instruments that do not indicate the manufacturer are all conventional products that can be obtained commercially.

[0070] Example 1

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

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

[0073] S20: Preparation of medicine

[0074] Weigh 20g of fly ash, grind and sieve to obtain fly ash powder of 48μm to 75μm, then mix with 1000g of 7% dilute hydrochloric acid solution, soak for 8h, filter and dry at 80℃ for 6h, then mix the dried powder with 1000g of 1mg / mL sodium hydroxide solution, soak for 8h, filter and dry at 80℃ for 6h to obtain modified fly ash; weigh 2.779g of modified fly ash, 0.139g of sodium alginate, 111.160g of deionized water and the sodium polyacrylate ferric oxide nanosphere powder prepared in step S10, mix them evenly and place them in a hydrothermal reactor for hydrothermal reaction at 160℃ for 24h, filter after the hydrothermal reaction and dry at 80℃ for 6h to obtain modified fly ash-coated sodium polyacrylate ferric oxide nanospheres, then weigh 0.908g of vinyl acetate and dissolve it in 2 7.240g methanol, and add the prepared modified fly ash wrapped sodium polyacrylate ferroferric oxide nanospheres and stir evenly, then add 0.091g benzoyl peroxide to the mixed slurry, then introduce nitrogen into the mixed slurry (nitrogen rate is 20mL / min) and heat the mixed slurry in a 40℃ water bath for 12h to initiate the polymerization of vinyl acetate. After the polymerization reaction, add 9.080g sodium hydroxide solution with a mass concentration of 1mg / mL, continue to heat in a 40℃ water bath for 24h to make the generated polyvinyl acetate alcoholyze to generate polyvinyl alcohol, filter after the water bath heating and dry at 80℃ for 6h to obtain the agent (based on the mass of the ferroferric oxide core, the mass percentage of sodium polyacrylate is 20%, the mass percentage of the modified fly ash is 60%, and the mass percentage of the polyvinyl alcohol is 10%). The FE-SEM picture of the agent is as shown in the attached figure. Figure 2 shown.

[0075] Example 2

[0076] S10: Preparation of sodium polyacrylate ferroferric 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. A sodium hydroxide solution with a mass concentration of 2 mg / mL was added dropwise while stirring in a low-temperature water bath at 5°C. When the pH value of the solution was neutral, 1.852 g of sodium acrylate was added. The mixed slurry was then placed in a hydrothermal reactor for hydrothermal reaction at 160°C for 2 h. After the hydrothermal reaction, the mixed slurry was placed in a beaker and 0.185 g of ammonium persulfate was added. Nitrogen was then introduced into the beaker (nitrogen rate was 40 mL / min) and heated in a water bath at 60°C for 8 h to initiate sodium acrylate polymerization. After the reaction, it was filtered and dried at 60°C for 12 h to obtain sodium polyacrylate ferrosoferric oxide nanosphere powder.

[0078] S20: Preparation of medicine

[0079] Weigh 20g of fly ash, grind and sieve to obtain fly ash powder of 48μm to 75μm, then mix with 2000g of 10% dilute hydrochloric acid solution, soak for 4h, filter and dry at 100℃ for 3h, then mix the dried powder with 2000g of 5mg / mL sodium hydroxide solution, soak for 4h, filter and dry at 100℃ for 3h to obtain modified fly ash; weigh 3.705g of modified fly ash, 0.741g of potassium alginate, 222.300g of deionized water and the sodium polyacrylate ferric oxide nanosphere powder obtained in step S10, mix them evenly and place them in a hydrothermal reactor for hydrothermal reaction at 180℃ for 12h, filter after the hydrothermal reaction and dry at 100℃ for 3h to obtain modified fly ash-coated sodium polyacrylate ferric oxide nanospheres, then weigh 1.816g of vinyl acetate solution In 90.800g of methanol, add the prepared modified fly ash-wrapped sodium polyacrylate ferroferric oxide nanospheres and stir evenly, then add 0.363g of azobisisobutyronitrile to the mixed slurry, then introduce nitrogen into the mixed slurry (nitrogen rate is 40mL / min) and heat the mixed slurry in a water bath at 60°C for 6h to initiate the polymerization of vinyl acetate. After the polymerization reaction, add 36.320g of a 5mg / mL sodium hydroxide solution, and continue to heat the reaction in a water bath at 60°C for 12h to hydrolyze the generated polyvinyl acetate to generate polyvinyl alcohol. After the water bath heating is completed, filter and dry at 100°C for 3h to obtain a reagent (based on the mass of the ferroferric oxide core, the mass percentage of sodium polyacrylate is 40%, the mass percentage of the modified fly ash is 80%, and the mass percentage of the polyvinyl alcohol is 20%).

[0080] Performance Testing

[0081] Adsorption effect of heavy metal ions

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

[0083] The test results of Example 1 and Example 2 are shown in Table 1.

[0084] Table 1

[0085]

[0086] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0087] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A monodisperse uniform agent for adsorbing heavy metal ions in circulating water of a coal-fired power plant, characterized in that: The agent has ferroferric oxide as the core, sodium polyacrylate as the agglomeration inhibitor, modified fly ash as the adsorbent, polyvinyl alcohol as the nanoparticle connector, and is prepared by a secondary hydrothermal reaction-secondary emulsion polymerization method; Based on the mass of the ferrosoferric 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 medicament according to claim 1, characterized in that: include: S10: Preparation of sodium polyacrylate ferroferric oxide nanospheres Weighing a divalent iron salt and a trivalent iron salt and dissolving them in deionized water, adding a sodium hydroxide solution dropwise during stirring in a low-temperature water bath, adding sodium acrylate when the pH value of the solution is neutral, and then placing the mixed slurry in a hydrothermal reactor for a first hydrothermal reaction, placing the mixed slurry in a beaker and adding a first initiator after the first hydrothermal reaction, then passing nitrogen into the beaker and performing a first water bath heating to initiate polymerization of the sodium acrylate, filtering after the reaction, and performing a first drying to obtain a sodium polyacrylate ferroferric oxide nanosphere powder; S20: Preparation of medicine Weigh fly ash, grind and sieve it, then mix it with dilute hydrochloric acid solution and soak it for 4h-8h, filter it and dry it for the second time, then mix the powder after the second drying with sodium hydroxide solution and soak it for 4h-8h, filter it and dry it to obtain modified fly ash; weigh the modified fly ash, morphology control agent, deionized water and the sodium polyacrylate ferroferric oxide nanosphere powder obtained in step S10, mix them evenly and place them in a hydrothermal reactor for a second hydrothermal reaction, filter and dry them after the second hydrothermal reaction to obtain modified fly ash-coated sodium polyacrylate ferroferric oxide nanospheres, then weigh vinyl acetate and dissolve it in methanol, add the modified fly ash-coated sodium polyacrylate ferroferric oxide nanospheres and stir them evenly, then add a second initiator to the mixed slurry, then pass nitrogen into the mixed slurry and heat the mixed slurry in a water bath for the second time to initiate polymerization of vinyl acetate, add sodium hydroxide solution after the polymerization reaction, heat it in a water bath for the third time to hydrolyze the generated polyvinyl acetate to generate polyvinyl alcohol, filter and dry it after the third water bath heating to obtain the agent.

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

2.

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

5. The method according to claim 2, characterized in that: In step S10, the temperature of the first hydrothermal reaction is 140°C-160°C, the time of the first hydrothermal reaction is 2h-4h, the temperature of the first drying is 40°C-60°C, 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 the sodium acrylate to the first initiator is 1:(0.05-0.1), the rate of nitrogen introduction is 20mL / min-40mL / min, the temperature of the first water bath heating is 40°C-60°C, and the time of the first water bath heating is 8h-16h.

7. The preparation method according to claim 2, characterized in that: The mesh size of the metal screen used for screening in step S20 is 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 the fly ash to the dilute hydrochloric acid solution is 1:(50-100), the mass ratio of the powder after the second drying to the sodium hydroxide solution is 1:(50-100), the temperature of the second drying is 80°C-100°C, and the time of the second drying is 3h-6h.

9. The preparation method according to claim 2, characterized in that: In step S20, 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).

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

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 the vinyl acetate, the 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 rate of introducing nitrogen is 20 mL / min-40 mL / min, the temperature of the second water bath heating is 40° C.-60° C., and the time of the second water bath heating is 6 h-12 h.

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

14. Use of the agent according to claim 1 in adsorbing heavy metal ions in circulating water of a coal-fired power plant.

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

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