Silver oxide nanodot loaded composite material as well as preparation method and application thereof

Abstract

The invention discloses a silver oxide nanodot loaded composite material and a preparation method thereof. The composite material can be used as an adsorbent for purifying radioactive iodine isotopes such as 131I, 129I and 125I in radioactive wastewater. A silver nitrate solution is used as a raw material, nano silver oxide particles are creatively loaded on the surface of a metal hydroxide carrier precursor in situ through a one-step method, silver oxide is anchored on the surface of the carrier through chemical bonds, the binding force is high, the particles are uniformly dispersed and are not agglomerated, and the excellent radioactive iodide ion adsorption effect and stability are shown. The preparation method has the advantages of simple process, low raw material price, no need of adding a large amount of alkaline substances to adjust the pH of the solution to be alkaline in the preparation process, no generation of a large amount of strong alkaline waste liquid, and easy realization of large-scale industrial production. When the composite material adsorbent loaded with the silver oxide nanodots is used for radioactive waste liquid treatment, the treatment cost of an adsorption method is greatly reduced, and the composite material adsorbent loaded with the silver oxide nanodots has an extremely wide commercial application prospect.

Description

Technical Field

[0001] This invention belongs to the field of adsorption material preparation technology, and particularly relates to a silver oxide nanodot composite material, its preparation method and application. Background Technology

[0002] In recent years, nuclear medicine technology has developed rapidly. Decay pools are essential supporting facilities for nuclear medicine, used to store and process radioactive waste liquids generated during decay therapy, the main nuclides of which are... 131 I. In accordance with the "Requirements for Radiation Protection and Safety in Nuclear Medicine" (HJ 1188-2021), including... 131 The waste liquid containing radioactive iodine should be stored for at least 180 days, making the decay pool volume a significant factor limiting the development of nuclear medicine. Currently, the main technologies for treating radioactive waste liquid include adsorption, ion exchange, and membrane separation, among which adsorption is considered the most promising method for treating radioactive iodine-containing waste liquid. Adsorption involves using solid adsorbents such as silver oxide to treat radioactive iodine wastewater, causing the radioactive iodine to associate or adhere to the surface or pores of the adsorbent, thereby removing the radioactive iodine from the water. Although adsorption has many advantages such as high efficiency and ease of operation, its high cost is due to the large consumption of adsorbents like silver oxide. Furthermore, the preparation of silver oxide adsorbents using existing technologies generates large amounts of alkaline waste liquid, further increasing the cost of adsorbents.

[0003] Chinese patent CN110813313B discloses a silver oxide / layered bimetallic hydroxide composite and its preparation and application. However, the preparation of this silver oxide composite not only generates a large amount of strongly alkaline waste liquid, but also leaves a small amount of triethanolamine residue in the composite. Furthermore, the silver oxide particles are relatively large, which is detrimental to the adsorption of radioactive iodine. Chinese patent CN108393062B discloses an amorphous silica material supported by nano-silver oxide. Although the preparation process of this supported silver oxide material does not generate alkaline waste liquid, the surface of the supported silver oxide material is relatively rough and consists of small particle agglomerates, thus hindering the adsorption of radioactive iodine. Chinese patent CN106390910B discloses a method for preparing an Ag₂O / niobic acid composite adsorbent material and its application. Although this adsorbent material is a nanoscale composite material, its preparation process also generates a large amount of alkaline waste liquid. Therefore, there is an urgent need to develop a silver oxide adsorbent material that is inexpensive to produce, has a simple preparation process, and does not generate a large amount of alkaline waste liquid. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a silver oxide nanoparticle composite material, its preparation method, and its application in purifying radioactive iodine isotopes in radioactive wastewater. This invention mixes a metal oxide carrier precursor with a silver salt in an aqueous solution. During the chemical reaction that generates silver oxide, the silver oxide is simultaneously loaded onto the carrier surface in situ. This invention provides a low-cost and simple process for preparing the silver oxide adsorbent. It does not generate large amounts of alkaline wastewater during preparation, and the resulting silver oxide particles have small particle sizes, are uniformly dispersed on the carrier surface, exhibit strong bonding, and show no agglomeration. This facilitates large-scale industrial production and has broad application prospects in the treatment of radioactive iodine-containing wastewater.

[0005] In a first aspect, the present invention discloses a method for preparing a silver oxide nanodot composite material, comprising the following steps: dissolving silver nitrate in deionized water, adding a metal oxide carrier precursor to the silver nitrate aqueous solution, stirring until the reaction is completed, separating the reaction products, and obtaining the silver oxide nanodot composite material.

[0006] Furthermore, the carrier precursor is at least one of MnO2, MgO, Fe2O3 and CaO.

[0007] Furthermore, the concentration of the silver nitrate aqueous solution is 2~20 mg / mL.

[0008] Furthermore, the mass ratio of silver nitrate to the carrier precursor is 0.2~1.

[0009] Furthermore, the reaction time is 0.5 to 24 hours.

[0010] Furthermore, after separating the reaction products, the reaction products are dried in an oven at 60~80℃ for 8~16 hours.

[0011] Secondly, the present invention also discloses a silver oxide nanodot composite material, the composite material comprising a metal hydroxide carrier and silver oxide particles distributed on the surface of the carrier, wherein the metal hydroxide carrier is a micron-sized particle and the silver oxide particles have a particle size of 5~20 nm.

[0012] Furthermore, the support is at least one of Mn(OH)2, Mg(OH)2, Fe(OH)3 and Ca(OH)2.

[0013] Thirdly, the present invention also discloses the application of a silver oxide nanoparticle composite material in purifying radioactive iodine isotopes in radioactive wastewater. The silver oxide nanoparticle composite material is prepared by the preparation method of the silver oxide nanoparticle composite material described in the first aspect of the present invention, or by using the silver oxide nanoparticle composite material described in the second aspect of the present invention.

[0014] Furthermore, the radioactive iodine isotope includes 131 I, 129 I and / or 125 I.

[0015] This invention provides a silver oxide nanoparticle-supported composite material and its preparation method. The silver oxide nanoparticle-supported composite material of this invention can be used as an adsorbent for purifying radioactive wastewater. 131 I, 129 I and 125 I-class radioactive iodine isotopes. Compared with the prior art, this application has at least the following beneficial effects: (1) The preparation method of the silver oxide nanodot composite material of the present invention does not require the addition of a large amount of alkaline substances to adjust the pH of the solution to strong alkalinity. After the silver oxide composite material is prepared, a large amount of alkaline waste liquid will not be generated, saving a large amount of post-treatment process of alkaline waste liquid, thereby reducing the production cost of silver oxide composite material.

[0016] (2) The silver oxide particles prepared by the present invention have a particle size of only 5~20nm. They can be uniformly dispersed on the surface of micron-sized carrier particles without agglomeration. They can provide a large number of adsorption sites for iodine ions, thereby significantly improving the adsorption effect of the composite material.

[0017] (3) The silver oxide particles prepared by the present invention are anchored on the surface of the carrier by chemical bonds and are not easy to fall off the surface of the carrier, thus greatly improving the stability of the composite material adsorbent.

[0018] (4) The metal oxide used in this invention serves as both a precursor and a carrier. While the metal oxide precursor reacts chemically with the silver salt in a neutral or weakly alkaline aqueous solution, the reaction product, silver oxide, is simultaneously loaded in situ onto the surface of the metal hydroxide carrier, thus preparing the silver oxide-loaded nanoparticle composite material in one step. This invention innovatively proposes a one-step in-situ method for preparing silver oxide nanoparticle composite materials. This method not only uses readily available and inexpensive raw materials but also features a simple process that eliminates the need for secondary treatment of strongly alkaline waste liquid, enabling large-scale industrial production. Furthermore, using the silver oxide nanoparticle composite material of this invention as an adsorbent for the disposal of radioactive waste liquid will significantly reduce the cost of adsorption treatment, thus possessing extremely broad commercial application prospects. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a SEM image of the silver oxide nanodot composite material prepared in Example 1 of the present invention.

[0021] Figure 2 This is a TEM image of the silver oxide nanodot composite material prepared in Example 1 of the present invention.

[0022] Figure 3 This is a TEM image of the silver oxide nanodot composite material prepared in Example 3 of the present invention.

[0023] Figure 4 This is a TEM image of the silver oxide nanodot composite material prepared in Example 5 of the present invention. Detailed Implementation

[0024] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0025] Unless otherwise specified, all temperatures mentioned herein are in degrees Celsius, and the preferred embodiments can be freely combined as needed. Those skilled in the art will understand that the data and parameters described in the examples are merely exemplary and do not constitute a limitation of the invention. All components used in the following examples and comparative examples are compounds known in the art, and all equipment used is equipment publicly known in the art. All components and equipment used in this invention can be obtained commercially or prepared using known techniques.

[0026] This invention provides a method for preparing a silver oxide nanoparticle composite material, comprising the following steps: dissolving silver nitrate in deionized water, adding a metal oxide support precursor to the silver nitrate aqueous solution, stirring until the reaction is complete, separating the reaction products, and obtaining the silver oxide nanoparticle composite material.

[0027] The preferred carrier precursor of this invention is at least one selected from MnO2, MgO, Fe2O3, and CaO. Of course, other inexpensive and readily available metal oxides can also be used as carrier precursors. Since the metal oxide used serves as both a precursor and a carrier, the selected metal oxide should be able to undergo a hydrolysis reaction in a neutral or weakly alkaline aqueous solution to generate a metal hydroxide, which then reacts with Ag. + A precipitation reaction occurs, forming an in-situ loading. It is understood that the present invention preferably uses metal oxides capable of hydrolysis in neutral aqueous solutions, thereby eliminating the need to adjust the solution to a weakly alkaline state and avoiding additional costs associated with the treatment of subsequent reaction waste.

[0028] The preferred concentration of the silver nitrate aqueous solution in this invention is 2-20 mg / mL, more preferably 2-4 mg / mL, and the preferred mass ratio of silver nitrate to the carrier precursor is 0.2-1. The reaction time required to complete in this invention is directly related to the concentration of the silver nitrate solution and the amount of metal oxide used. Under conventional stirring conditions, 0.5-24 hours is usually sufficient to complete the entire reaction. It is understood that the reaction time can be appropriately extended to ensure complete completion of the reaction.

[0029] This invention utilizes common solid-liquid separation methods such as centrifugation or filtration to separate the reaction products from the aqueous solution. The separated reaction products can be naturally dried to remove moisture. Alternatively, to accelerate the drying process, an oven can be used, for example, placing the reaction products in an oven at 60-80°C for 8-16 hours, as long as the moisture content of the products is effectively removed.

[0030] The reaction mechanism for preparing the silver oxide nanodot composite material of this invention includes three steps: (1) The carrier precursor undergoes hydrolysis in neutral or weakly alkaline aqueous solution to generate the corresponding hydroxide: MO + H2O = M(OH)2; (2) Ag in the solution + Ions and OH groups on the surface of metal oxide support - Ions undergo precipitation reaction: Ag + +OH - =AgOH; (3) Because AgOH is extremely unstable in aqueous solution, it will decompose rapidly into nano Ag2O: 2AgOH=Ag2O+H2O.

[0031] Therefore, this invention creatively proposes a one-step method for preparing in-situ supported silver oxide nanoparticle composite materials. To this end, this invention also provides a supported silver oxide nanoparticle composite material, comprising a metal hydroxide support and silver oxide particles distributed on the surface of the support. The metal hydroxide support is micron-sized particles, and the silver oxide particles have a particle size of 5-20 nm. Preferably, the support is at least one of Mn(OH)₂, Mg(OH)₂, Fe(OH)₃, and Ca(OH)₂. Because the nano-silver oxide prepared by this invention has a small particle size and is uniformly dispersed on the support surface without agglomeration, it can provide a large number of iodine ion adsorption sites. Therefore, this invention also provides an application of the supported silver oxide nanoparticle composite material in purifying radioactive iodine isotopes in radioactive wastewater. This supported silver oxide nanoparticle composite material can be prepared by the method of this invention. As an adsorbent, this supported silver oxide nanoparticle composite material can effectively adsorb and purify radioactive iodine isotopes in radioactive wastewater. 131 I, 129 I and 125 I-type radioactive iodine isotopes.

[0032] The present invention will now be described in more detail with reference to exemplary embodiments. The following embodiments or experimental data are intended to illustrate the present invention by way of example, and those skilled in the art should understand that the present invention is not limited to these embodiments or experimental data.

[0033] Example 1 Prepare an adsorbent supported on silver oxide nanodot composite material.

[0034] 0.2 g of silver nitrate was dissolved in 100 mL of deionized water. 1 g of MgO carrier precursor was added to a 2 mg / mL silver nitrate aqueous solution (the mass ratio of silver nitrate to carrier precursor was 0.2). The mixture was stirred and reacted for 5 h. After the reaction was completed, the reaction product obtained by filtration was placed in a 60 °C oven and dried for 10 h to obtain the silver oxide nanodot composite adsorbent.

[0035] The composite material prepared in this embodiment was subjected to SEM and TEM detection, and the results are as follows: Figure 1-2 As shown. By Figure 1-2 It can be seen that a large number of nano-sized Ag2O particles are deposited on the surface of micron-sized sheet-like Mg(OH)2 particles. The Ag2O particle size is 5~20nm. The Ag2O particles are uniformly distributed on the carrier surface and no agglomeration occurs, thus providing a large number of adsorption sites for iodine ions.

[0036] Example 2 Prepare an adsorbent supported on silver oxide nanodot composite material.

[0037] 0.2 g of silver nitrate was dissolved in 10 mL of deionized water, and 1 g of MnO2 carrier precursor was added to a 20 mg / mL silver nitrate aqueous solution (the mass ratio of silver nitrate to carrier precursor was 0.2). The mixture was stirred and reacted for 0.5 h. After the reaction was completed, the reaction product obtained by filtration was placed in a 70 °C oven and dried for 8 h to obtain the silver oxide nanodot composite adsorbent.

[0038] Example 3 Prepare an adsorbent supported on silver oxide nanodot composite material.

[0039] 0.6 g of silver nitrate was dissolved in 150 mL of deionized water, and 1 g of MnO2 carrier precursor was added to a silver nitrate aqueous solution with a concentration of 4 mg / mL (the mass ratio of silver nitrate to carrier precursor was 0.6). The mixture was stirred and reacted for 24 h. After the reaction was completed, the reaction product obtained by filtration was placed in an oven at 80 °C and dried for 16 h to obtain the silver oxide nanodot composite adsorbent.

[0040] The composite material prepared in this embodiment was subjected to TEM detection, and the results are as follows: Figure 3 As shown. By Figure 3 It is evident that a large number of uniformly distributed nano-sized Ag2O particles are deposited on the carrier surface, thus providing a large number of adsorption sites for iodine ions.

[0041] Example 4 Prepare an adsorbent supported on silver oxide nanodot composite material.

[0042] 0.6 g of silver nitrate was dissolved in 30 mL of deionized water, and 1 g of MgO carrier precursor was added to a 20 mg / mL silver nitrate aqueous solution (the mass ratio of silver nitrate to carrier precursor was 0.6). The mixture was stirred and reacted for 10 h. After the reaction was completed, the reaction product obtained by filtration was placed in a 70 °C oven and dried for 10 h to obtain the silver oxide nanodot composite adsorbent.

[0043] Example 5 Prepare an adsorbent supported on silver oxide nanodot composite material.

[0044] 1 g of silver nitrate was dissolved in 100 mL of deionized water, and 1 g of Fe2O3 carrier precursor was added to a 10 mg / mL silver nitrate aqueous solution (the mass ratio of silver nitrate to carrier precursor was 1). The mixture was stirred and reacted for 10 h. After the reaction was completed, the reaction product obtained by filtration was placed in a 70 °C oven and dried for 10 h to obtain the silver oxide nanodot composite adsorbent.

[0045] The composite material prepared in this embodiment was subjected to TEM detection, and the results are as follows: Figure 4 As shown. By Figure 4 It is evident that a large number of uniformly distributed nano-sized Ag2O particles are deposited on the carrier surface, thus providing a large number of adsorption sites for iodine ions.

[0046] Example 6 Prepare an adsorbent supported on silver oxide nanodot composite material.

[0047] 1 g of silver nitrate was dissolved in 50 mL of deionized water, and 1 g of CaO carrier precursor was added to a 20 mg / mL silver nitrate aqueous solution (the mass ratio of silver nitrate to carrier precursor was 1). The mixture was stirred and reacted for 16 h. After the reaction was completed, the reaction product obtained by filtration was placed in an 80 °C oven and dried for 16 h to obtain the silver oxide nanodot composite adsorbent.

[0048] Comparative Example 1 Prepare an adsorbent supported on silver oxide nanodot composite material.

[0049] 0.2 g of silver nitrate was dissolved in 100 mL of deionized water, and 1 g of ZnO carrier precursor was added to a 2 mg / mL silver nitrate aqueous solution (the mass ratio of silver nitrate to carrier precursor was 0.2). The mixture was stirred and reacted for 5 h. After the reaction was completed, the reaction product obtained by filtration was placed in a 60 °C oven and dried for 10 h to obtain the silver oxide nanodot composite adsorbent.

[0050] Comparative Example 2 Prepare an adsorbent supported on silver oxide nanodot composite material.

[0051] 0.2 g of silver nitrate was dissolved in 200 mL of deionized water, and 1 g of MgO carrier precursor was added to a silver nitrate aqueous solution with a concentration of 1 mg / mL (the mass ratio of silver nitrate to carrier precursor was 0.2). The mixture was stirred and reacted for 5 h. After the reaction was completed, the reaction product obtained by filtration was placed in an oven at 60 °C and dried for 10 h to obtain the silver oxide nanodot composite adsorbent.

[0052] Comparative Example 3 Prepare an adsorbent supported on silver oxide nanodot composite material.

[0053] 0.2 g of silver nitrate was dissolved in 80 mL of deionized water, and 1 g of MnO2 carrier precursor was added to a silver nitrate aqueous solution with a concentration of 25 mg / mL (the mass ratio of silver nitrate to carrier precursor was 0.2). The mixture was stirred and reacted for 5 h. After the reaction was completed, the reaction product obtained by filtration was placed in an oven at 60 °C and dried for 10 h to obtain the silver oxide nanodot composite adsorbent.

[0054] Comparative Example 4 Prepare an adsorbent supported on silver oxide nanodot composite material.

[0055] 0.2 g of silver nitrate was dissolved in 100 mL of deionized water, and 1.2 g of MnO2 carrier precursor was added to a 2 mg / mL silver nitrate aqueous solution (the mass ratio of silver nitrate to carrier precursor was 0.167). The mixture was stirred and reacted for 5 h. After the reaction was completed, the reaction product obtained by filtration was placed in a 60 °C oven and dried for 10 h to obtain the silver oxide nanodot composite adsorbent.

[0056] Comparative Example 5 Prepare an adsorbent supported on silver oxide nanodot composite material.

[0057] 1.1 g of silver nitrate was dissolved in 100 mL of deionized water, and 1 g of MnO2 carrier precursor was added to a silver nitrate aqueous solution with a concentration of 11 mg / mL (the mass ratio of silver nitrate to carrier precursor was 1.1). The mixture was stirred and reacted for 5 h. After the reaction was completed, the reaction product obtained by filtration was placed in an oven at 60 °C and dried for 10 h to obtain the silver oxide nanodot composite adsorbent.

[0058] Adsorption performance test The silver oxide nanoparticle composite materials prepared in Examples 1-6 and Comparative Examples 1-5 were used as adsorbents to test their adsorption effect on I ions in wastewater. The test results are shown in Table 1.

[0059] Test equipment: Iodide ions were measured using a concentration UV-Vis spectrophotometer (PE Corporation, Lambda 750).

[0060] Performance testing methods: All experiments were conducted using non-radioactive iodine as a substitute to avoid the toxicity of radioactive iodine. A concentration of 5 × 10⁻⁶ was prepared by dissolving sodium iodide in 1 liter of deionized water. 5An iodide ion solution of Bq / L was prepared. Adsorbents prepared in Examples 1-6 and Comparative Examples 1-5 were mixed with the iodide ion solution at a ratio of 5 g: 1000 mL in a beaker on a magnetic stirrer for adsorption experiments. The pH was adjusted with sodium hydroxide and nitric acid solutions, and the concentration of iodide ions was determined by absorbance at 226 nm using a UV-Vis spectrophotometer.

[0061] Table 1 Adsorption performance test results

[0062] Performance test results analysis As shown in Table 1, the performance of Examples 1-6 was all above 96%, significantly better than that of Comparative Examples 1-5, with the highest iodide ion removal rate reaching 99.7%. This is attributed to the in-situ formation of nano-silver oxide particles on their surface. Nano-silver oxide particles have a large number of surface atoms, and their insufficient coordination number and high surface energy make these atoms easily combine with other atoms to stabilize them, thus exhibiting high chemical activity. The nano-silver oxide particles react with iodide ions in the solution to form a stable insoluble AgI, which captures and fixes the iodide ions in the solution on its surface, achieving the removal of iodide ions from the waste liquid.

[0063] In summary, this invention provides a silver oxide nanoparticle-supported composite material and its preparation method. This silver oxide nanoparticle-supported composite material can be used as an adsorbent for adsorbing and purifying radioactive wastewater. 131 I, 129 I and 125 This invention creatively and successfully loads nano-silver oxide particles in situ onto the surface of a carrier precursor using a one-step method. The silver oxide is chemically anchored to the carrier surface, exhibiting uniform dispersion and no agglomeration, providing numerous iodine ion adsorption sites and demonstrating excellent adsorption performance for radioactive iodine ions. The preparation method of this invention is simple, uses inexpensive raw materials, and does not generate large amounts of strongly alkaline waste liquid, making it easy to achieve large-scale industrial production. Using the silver oxide nanoparticle composite adsorbent of this invention for the treatment of radioactive waste liquid will significantly reduce the cost of adsorption methods and has extremely broad commercial application prospects.

[0064] All materials used in this invention are commercially available and can be purchased from retail sources. The above description is merely a preferred embodiment of the invention and is not intended to limit the invention. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for preparing a composite material supported on silver oxide nanodots, characterized in that, Includes the following steps: Silver nitrate was dissolved in deionized water, and the metal oxide support precursor was added to the silver nitrate aqueous solution. The mixture was stirred until the reaction was completed, and the reaction products were separated to obtain the silver oxide nanoparticle composite material.

2. The method for preparing the silver oxide nanodot composite material according to claim 1, characterized in that, The carrier precursor is at least one of MnO2, MgO, Fe2O3 and CaO.

3. The method for preparing the silver oxide nanodot composite material according to claim 1, characterized in that, The concentration of the silver nitrate aqueous solution is 2~20 mg / mL.

4. The method for preparing the silver oxide nanodot composite material according to claim 1, characterized in that, The mass ratio of silver nitrate to the carrier precursor is 0.2~1.

5. The method for preparing the silver oxide nanodot composite material according to claim 1, characterized in that, The reaction time is 0.5 to 24 hours.

6. The method for preparing the silver oxide nanodot composite material according to claim 1, characterized in that, After separating the reaction products, the reaction products are dried in an oven at 60-80°C for 8-16 hours.

7. A composite material supported on silver oxide nanodots, characterized in that, The composite material includes a metal hydroxide carrier and silver oxide particles distributed on the surface of the carrier. The metal hydroxide carrier consists of micron-sized particles, and the silver oxide particles have a particle size of 5-20 nm.

8. The silver oxide nanodot composite material according to claim 7, characterized in that, The carrier is at least one of Mn(OH)2, Mg(OH)2, Fe(OH)3 and Ca(OH)2.

9. The application of a silver oxide nanoparticle-supported composite material in purifying radioactive iodine isotopes in radioactive wastewater, characterized in that... The silver oxide nanodot composite material is prepared by the method for preparing the silver oxide nanodot composite material according to any one of claims 1-6, or by using the silver oxide nanodot composite material according to claim 7 or 8.

10. The application of the silver oxide nanoparticle composite material according to claim 9 in the purification of radioactive iodine isotopes in radioactive wastewater, characterized in that, The radioactive iodine isotope includes 131 I, 129 I and / or 125 I.

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