Preparation method of porous sodium zirconium phosphate beads for uranium adsorption

Abstract

The application relates to the field of radiochemistry, in particular to a preparation method of porous sodium zirconium phosphate pellets for uranium adsorption, sodium zirconium phosphate powder is weighed, polyurethane is measured, the obtained dough-like material is stirred uniformly in a beaker, the sample is put into a roller for polishing for 10 minutes to obtain pellet samples, and the samples are placed into a vacuum drying box and dried at 60 DEG C under constant temperature conditions for 10 hours. The application utilizes the characteristics that the alpha-ZrP is a layered compound which is easy to synthesize and has good thermal stability and acid resistance, the ion exchange capacity of the alpha-ZrP is nearly 6 times that of clay, the alpha-ZrP is an excellent matrix for preparing intercalation compounds, layer column catalytic materials and polymer / layered inorganic nanocomposites, and the alpha-ZrP is widely applied to the field of nuclide adsorption, so that the preparation cost of the adsorbent is greatly reduced.

Description

Technical Field

[0001] This invention relates to the field of radiochemistry, specifically to a method for preparing porous sodium-type zirconium phosphate microspheres for uranium adsorption. Background Technology

[0002] With the continuous development of the economy, the coal-based energy structure can no longer meet the growing energy demand, and there is an urgent need to adjust and diversify and find new sustainable energy sources. Among the candidates for new energy sources, nuclear energy has obvious economic and environmental advantages compared to wind, hydro and solar energy, which face huge cost and technical limitations.

[0003] However, the operation, maintenance, and decommissioning of nuclear reactors will generate a large amount of radioactive waste, and leaks in radionuclide storage tanks or nuclear power plant accidents may also lead to radioactive pollution of water bodies. Among these, the total amount of radionuclides contained in radioactive wastewater accounts for a relatively high proportion of the total amount of original radioactive waste, posing a huge threat to humans and life on Earth. Therefore, how to treat radioactive waste, separate and remove uranium from U(VI) radioactive waste liquid, and control the spread of radioactive pollution require widespread attention.

[0004] Traditional methods for separating and enriching uranium in aqueous solutions include ion exchange, chemical precipitation, solvent extraction, and adsorption. Among these, adsorption utilizes the special functional groups on the surface of solid-phase adsorbent materials to adsorb one or more adsorbates from radioactive wastewater, thereby removing or recovering the target radionuclide. The radionuclide can then be reused through desorption. Adsorption treatment of radioactive wastewater does not introduce secondary pollutants. The precipitate formed by the adsorbent and radionuclide can be easily separated from the water, and the radionuclide can be reused through desorption. It is a widely applicable wastewater treatment technology. Adsorption has been extensively developed and applied over many years, and research on adsorption materials is relatively mature. Adsorption is considered a method with large-scale application potential due to its high efficiency, speed, and ease of operation. However, current research on adsorption materials, both domestically and internationally, mainly focuses on powdered and micro-particle adsorbents, which are not conducive to the recovery and reuse of adsorbents and radionuclides, and are not suitable for the industrialization and commercialization of wastewater treatment technology.

[0005] Therefore, based on the above reasons, it is necessary to design a method for preparing porous sodium-type zirconium phosphate microspheres for uranium adsorption. This method is based on the practical application scenario of U(VI) adsorption treatment in radioactive wastewater, and aims to prepare porous sodium-type zirconium phosphate microspheres with stable morphology and properties for U(VI) adsorption. This will solve the shortcomings of traditional U(VI) adsorbents in radioactive wastewater, such as high preparation and treatment costs, difficulty in recovery and clogging of powdered or micro-particle adsorbents leading to reduced column separation efficiency, and difficulty in industrialization and commercial application. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing porous sodium-type zirconium phosphate microspheres for uranium adsorption. Based on the practical application scenario of U(VI) adsorption treatment of radioactive wastewater, this invention prepares porous sodium-type zirconium phosphate microspheres with stable morphology and properties for U(VI) adsorption, solving the problems of high preparation cost and high treatment cost of traditional U(VI) adsorbents for radioactive wastewater, and the disadvantages of powdered or micro-particle adsorbents being difficult to recover, easy to clog and thus reduce column separation efficiency, and difficult to industrialize and apply.

[0007] To achieve the above objectives, the present invention provides a method for preparing porous sodium-type zirconium phosphate microspheres for uranium adsorption, comprising the following steps:

[0008] S1, Weigh 100g of sodium zirconium phosphate powder and measure 65-70ml of polyurethane, then stir evenly in a beaker;

[0009] S2, The dough-like material obtained by uniformly mixing sodium zirconium phosphate powder and polyurethane is placed into the feed inlet of the pelletizing machine;

[0010] S3, Place the sample obtained from the pelletizing machine outlet into a drum for polishing for 10 minutes to obtain small ball samples;

[0011] S4, Place the polished small ball sample into a vacuum drying oven and dry it at a constant temperature of 60℃ for 10 hours;

[0012] S5, Remove the sample and allow it to cool to room temperature to obtain porous sodium-type zirconium phosphate microspheres;

[0013] Sodium-type zirconium phosphate includes two different crystal structures: α-zirconium phosphate Zr(HPO4)2·H2O and γ-zirconium phosphate ZrPO4(H2PO4)·2H2O;

[0014] Zirconium phosphate (ZP) has a regular lamellar structure and strong ion exchange capacity, with an interlayer spacing of 0.76 nm. ZP is composed of ZrO6 octahedra and PO3(OH) tetrahedra, stacked in an ABAB pattern. Each layer consists of Zr atoms in approximately the same plane and two layers of PO3-OH sandwiching the Zr atoms. The PO3-OH groups pointing into the space between the layers share three oxygen atoms with the Zr atoms. The hydrogen protons on the P-OH groups can be exchanged. Water molecules in the space between the layers form hydrogen bonds with the P-OH groups on one layer. The interaction force between the layers is van der Waals force.

[0015] The interlayer spacing of γ-zirconium phosphate is 1.22 nm. In each layer, Zr atoms are located on two parallel planes, with PO4 and H2PO4 groups as bridges. The four oxygen atoms of the PO4 group are shared with four Zr atoms, while the two oxygen atoms of the H2PO4 group are shared with two Zr atoms. The remaining two -OH groups point into the space between the layers. The interaction between the layers is the hydrogen bond force formed by the H2O molecule and the =P(OH)2 on the two adjacent layers.

[0016] The beneficial technical effects of this invention are as follows:

[0017] Taking advantage of the excellent thermal stability and acid resistance of α-ZrP, as well as its easy synthesis as a layered compound, and the fact that the ion exchange capacity of α-ZrP is nearly 6 times that of clay, it is an excellent matrix for preparing intercalated compounds, layered column catalytic materials, and polymer / layered inorganic nanocomposites. It has been widely used in the field of radionuclide adsorption, greatly reducing the preparation cost of adsorbents.

[0018] The adsorbent of the present invention is a porous microsphere with a diameter of ≥3mm, which has the potential for industrial application compared with traditional powder adsorbents. Attached image description:

[0019] Figure 1 This is a schematic diagram of the structures of α-zirconium phosphate and γ-zirconium phosphate used in this invention.

[0020] Figure 2 This is a schematic diagram of the pellet-making machine of the present invention.

[0021] Figure 3 This is a schematic diagram of the zirconium phosphate microspheres of the present invention.

[0022] Figure 4 This is a schematic diagram of zirconium phosphate microspheres after soaking for multiple times according to the present invention.

[0023] Figure 5 This is a schematic diagram of a cross-sectional SEM image of the porous sodium-type zirconium phosphate microspheres of the present invention. Detailed Implementation

[0024] See Figures 1-5 This invention provides a method for preparing porous sodium-type zirconium phosphate microspheres for uranium adsorption, comprising the following steps:

[0025] S1, Weigh 100g of sodium zirconium phosphate powder and measure 65-70ml of polyurethane, then stir evenly in a beaker;

[0026] S2, The dough-like material obtained by uniformly mixing sodium zirconium phosphate powder and polyurethane is placed into the feed inlet of the pelletizing machine;

[0027] S3, Place the sample obtained from the pelletizing machine outlet into a drum for polishing for 10 minutes to obtain small ball samples;

[0028] S4, Place the polished small ball sample into a vacuum drying oven and dry it at a constant temperature of 60℃ for 10 hours;

[0029] S5, Remove the sample and allow it to cool to room temperature to obtain porous sodium-type zirconium phosphate microspheres;

[0030] Zirconium phosphate (ZrP) has a large specific surface area and a stable layered structure. It is insoluble in organic solvents and water, and can withstand strong acids and alkalis of a certain strength. It also has high mechanical strength, good thermal stability, and good chemical stability.

[0031] Sodium-type zirconium phosphate includes two different crystal structures: α-zirconium phosphate Zr(HPO4)2·H2O and γ-zirconium phosphate ZrPO4(H2PO4)·2H2O;

[0032] Zirconium phosphate (ZP) has a regular lamellar structure and strong ion exchange capacity, with an interlayer spacing of 0.76 nm. ZP is composed of ZrO6 octahedra and PO3(OH) tetrahedra, stacked in an ABAB pattern. Each layer consists of Zr atoms in approximately the same plane and two layers of PO3-OH sandwiching the Zr atoms. The PO3-OH groups pointing into the space between the layers share three oxygen atoms with the Zr atoms. The hydrogen protons on the P-OH groups can be exchanged. Water molecules in the space between the layers form hydrogen bonds with the P-OH groups on one layer. The interaction force between the layers is van der Waals force.

[0033] The interlayer spacing of γ-zirconium phosphate is 1.22 nm. In each layer, Zr atoms are located on two parallel planes, with PO4 and H2PO4 groups as bridges. The four oxygen atoms of the PO4 group are shared with four Zr atoms, while the two oxygen atoms of the H2PO4 group are shared with two Zr atoms. The remaining two -OH groups point into the space between the layers. The interaction between the layers is the hydrogen bond force formed by the H2O molecule and the =P(OH)2 on the two adjacent layers.

[0034] like Figure 4 As shown, the prepared porous sodium-type zirconium phosphate microspheres were soaked in deionized water. The results showed that after soaking for 24h, 36h, 48h and 60h, the porous sodium-type zirconium phosphate microspheres did not dissolve and could maintain their sphere morphology.

[0035] The prepared porous sodium-type zirconium phosphate microspheres were characterized and analyzed by SEM, FTIR, EDS, XRD, XPS, and BET, which proved that the porous sodium-type zirconium phosphate microspheres prepared in this invention have an internal porous structure and good adsorption capacity for uranium in aqueous solutions.

[0036] like Figure 5 As shown, the cross-section of the porous polyurethane / sodium zirconium phosphate microspheres has a porous honeycomb structure, with grooves of varying depths attached to the surface of the pore channels. This structure ensures a sufficiently large specific surface area for the microspheres, laying the structural foundation for their excellent adsorption capacity.

[0037] The above are merely preferred embodiments of the present invention, intended only to aid in understanding the method and core ideas of this application. The scope of protection of the present invention is not limited to the above embodiments; all technical solutions falling within the scope of the present invention's concept are within its protection. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

[0038] This invention fundamentally solves the shortcomings of existing technologies for U(VI) adsorbents in radioactive wastewater, such as high preparation and treatment costs, difficulty in recycling powdered or micro-particle adsorbents leading to clogging and reduced column separation efficiency, and difficulty in industrial application. By utilizing the characteristics of zirconium phosphate (ZrP), which has a large specific surface area and stable layered structure, is insoluble in organic solvents and water, can withstand strong acids and alkalis of a certain strength, and has high mechanical strength, good thermal stability and chemical stability, this invention enables its widespread application in the field of radionuclide adsorption, greatly reducing the preparation cost of adsorbents and increasing the potential for industrial application.

Claims

1. Use of a porous sodium zirconium phosphate pellet in U(Ⅵ) adsorption, characterized in that, Includes the following steps: S1, Weigh 100g of sodium zirconium phosphate powder, measure 65-70ml of polyurethane, and stir evenly in a beaker; S2, The dough-like material obtained by uniformly mixing sodium zirconium phosphate powder and polyurethane is placed into the feed inlet of the pelletizing machine; S3, Place the sample obtained from the pelletizing machine outlet into a drum for polishing for 10 minutes to obtain small ball samples; S4. Place the polished small ball sample into a vacuum drying oven and dry it at a constant temperature of 60℃ for 10 hours; S5, Remove the sample and allow it to cool to room temperature to obtain porous sodium-type zirconium phosphate microspheres; The sodium-type zirconium phosphate includes two different crystal structures: α-zirconium phosphate Zr(HPO4)2·H2O and γ-zirconium phosphate ZrPO4(H2PO4)·2H2O. The α-zirconium phosphate has a regular lamellar structure and strong ion exchange performance, with an interlayer spacing of 0.76 nm. The α-zirconium phosphate is composed of ZrO6 octahedra and PO3(OH) tetrahedra connected together, with the layers stacked in an ABAB manner. Each layer consists of Zr atoms in the same plane and two layers of PO3-OH sandwiching the Zr atoms in between. The PO3-OH groups pointing into the space of the layer share three oxygen atoms with the Zr atoms. The hydrogen protons on the P-OH groups can be exchanged. Water molecules in the space of the layer form hydrogen bonds with the P-OH on one layer. The interaction force between the layers is van der Waals force. The interlayer spacing of the γ-zirconium phosphate is 1.22 nm. In each layer, the Zr atoms are located on two parallel planes, with PO4 and H2PO4 groups as bridges in between. The four oxygen atoms of the PO4 group are shared with the four Zr atoms, while the two oxygen atoms of the H2PO4 group are shared with the two Zr atoms. The remaining two -OH groups point into the space within the layer. The interaction between the layers is the hydrogen bond force formed by the H2O molecule and the =P(OH)2 on the two adjacent layers.

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