Difunctional gypsum admixture as well as preparation method and application thereof

Abstract

The invention discloses a difunctional gypsum admixture as well as a preparation method and application thereof, and belongs to the technical field of building material admixtures. According to the invention, vegetable tannin is coated on the surfaces of metal oxide nanoparticles, and another metal ion is coordinated on a tannic acid coating layer to assemble core-shell structure nanoparticles, so that the difunctional gypsum admixture is obtained. The difunctional gypsum admixture provided by the invention can delay the gypsum coagulation time and increase the plasticity time of gypsum slurry, after the admixture accounting for 10-50% of the mass of gypsum is introduced, the initial setting time of the gypsum is prolonged to 20-70 min, meanwhile, the assembly of the core-shell structure gives full play to the synergistic effect of the two high Z elements, efficient shielding of the gypsum to X rays is realized, and the strength of the gypsum is improved. Meanwhile, the problem that metal oxide nanoparticles are difficult to uniformly and stably load on gypsum crystals is solved.

Description

Technical Field

[0001] This invention belongs to the field of building material admixtures technology, specifically relating to a bifunctional gypsum admixture, its preparation method, and its application. Background Technology

[0002] With the widespread use of X-rays in medical diagnosis, industrial inspection, and safety monitoring, radiation protection has become an increasingly important concern. Traditional protection methods primarily rely on lead and its compounds, such as lead plates or lead-containing glass, which offer good shielding in the low-energy X-ray range. However, lead is dense, easily oxidized, and highly toxic, increasing the difficulty of transportation and construction, and posing potential hazards to the environment and human health. Furthermore, lead has limited absorption capacity for medium- to high-energy (approximately 40–90 keV) X-rays. Therefore, developing novel, environmentally friendly, and highly efficient lead-free protective materials has become a research hotspot.

[0003] From the perspective of the interaction mechanism between X-rays and matter, X-rays undergo two main processes when penetrating materials: the photoelectric effect and Compton scattering. In the photoelectric effect, photons transfer energy to outer electrons of atoms and are absorbed; while in Compton scattering, high-energy photons undergo inelastic collisions with electrons, resulting in partial energy transfer and attenuation. Generally, elements with higher atomic numbers (high-Z elements) respond more strongly to the photoelectric effect, thus achieving better X-ray shielding effects at the same thickness. High-Z elements, due to their high atomic numbers and complex electronic structures, exhibit unique advantages in constructing lightweight and efficient X-ray shielding materials. However, according to radiation protection theory, each collision between a photon and the outer electron of a high-Z element leads to energy attenuation. This means that as the collision process continues, the attenuation capability of a single high-Z element for photon energy gradually decreases because the attenuated photon energy does not match its absorption edge, resulting in a lower attenuation coefficient.

[0004] Building gypsum is an inorganic cementitious material widely used in decoration, molds, and precast components, possessing advantages such as light weight, low cost, and high renewability. However, its short curing time (typically about 5-10 minutes) limits its workability and storage / transportation time. Studies have found that directly incorporating high-Z element nanoparticles into gypsum can enhance its X-ray shielding performance to some extent. However, due to the high surface activity and easy aggregation of nanoparticles, it promotes the crystallization of dihydrate gypsum crystals, accelerating the setting process, which is detrimental to the molding and subsequent processing of gypsum.

[0005] Therefore, how to improve the X-ray shielding effect of gypsum while maintaining its mechanical properties, and at the same time improve its setting and dispersion characteristics, has become a key scientific problem that urgently needs to be solved in the field of lead-free protective building materials. Summary of the Invention

[0006] The purpose of this invention is to provide a bifunctional gypsum admixture, its preparation method, and its application. This invention assembles two matching high-Z elements into a core-shell structure, allowing X-ray photons to collide multiple times within the core-shell structure. This fully leverages the synergistic effect between the different high-Z elements, achieving efficient attenuation and absorption of X-ray photon energy.

[0007] To achieve the above objectives, the present invention provides the following technical solution: One of the technical solutions of this invention is to provide a method for preparing a bifunctional gypsum admixture, comprising the following steps: Plant tannins were added to a metal oxide nanoparticle dispersion, and after stirring and reacting, another metal element ion was added and the pH was adjusted to 6.5-7.5. After stirring and reacting, the bifunctional gypsum admixture was obtained. The metal oxide nanoparticles include: erbium oxide nanoparticles, bismuth oxide nanoparticles, tungsten oxide nanoparticles, lanthanum oxide nanoparticles, tin oxide nanoparticles, or cesium oxide nanoparticles. The other metallic element ion includes: barium ion, tin ion or gadolinium ion.

[0008] Preferably, the particle size of the metal oxide nanoparticles is 50–200 nm.

[0009] Preferably, the content of metal oxide nanoparticles in the metal oxide nanoparticle dispersion is 5wt% to 10wt%.

[0010] Preferably, the dispersant in the metal oxide nanoparticle dispersion is water.

[0011] Preferably, the plant tannins include one or more of gallic acid and catechins.

[0012] Preferably, the concentration of the plant tannin in the reaction system is 15–30 mmol / L.

[0013] Preferably, the concentration of the other metal element ion in the reaction system is 30–60 mmol / L.

[0014] Optionally, the pH value can be adjusted using a 0.1M NaOH solution.

[0015] Preferably, after adding the plant tannin, the stirring speed of the reaction is 1500-2000 r / min, the reaction temperature is 40-60℃, and the reaction time is 1-2 h.

[0016] Preferably, after adjusting the pH value, the stirring speed of the reaction is 1500-2000 r / min, the reaction temperature is 40-60℃, and the reaction time is 16-10 h.

[0017] Preferably, the process includes a washing and drying step after pH adjustment and reaction.

[0018] More preferably, the washing is a washing with water at least twice.

[0019] More preferably, the drying temperature is 40–60°C and the drying time is 8–12 hours.

[0020] The second technical solution of the present invention is to provide a bifunctional gypsum admixture prepared according to the above-mentioned preparation method of bifunctional gypsum admixture.

[0021] The third technical solution of the present invention provides an application of the above-mentioned bifunctional gypsum admixture in the preparation of X-ray shielding gypsum.

[0022] The fourth technical solution of the present invention provides an X-ray shielding plaster, which, by mass percentage, comprises: 50% to 90% plaster powder and 10% to 50% of the above-mentioned bifunctional plaster additive.

[0023] This invention introduces core-shell structured nanoparticles composed of two high-Z elements into a gypsum-based material by adding an additive. This allows X-ray photons to undergo multiple effective collisions between the nanoparticle core and shell when penetrating the gypsum, thus achieving highly efficient X-ray shielding. Compared to introducing a single high-Z element, introducing two high-Z elements with complementary weak absorption regions assembled into a core-shell structure can fully leverage the synergistic effect of different elements, thereby significantly improving the X-ray shielding performance of the material. Simultaneously, plant tannins are coated onto the surface of the metal oxide nanoparticles based on π-π bond interactions. The nanoparticles coated with plant tannins exhibit multiple intermolecular forces, enhancing their dispersibility and stability. This solves the problems of uneven dispersion and unstable loading that occur when metal oxide nanoparticles are directly loaded onto a substrate, increasing the probability of effective collisions between X-ray photons and nanoparticles, thereby improving the material's X-ray shielding performance. Furthermore, plant tannins contain a large number of phenolic hydroxyl groups, which can stably coordinate with metal ions, assembling the metal oxide nanoparticles and metal ions into a core-shell structure, fully leveraging the synergistic effect of different elements, and further enhancing the material's X-ray shielding performance. In addition, these phenolic hydroxyl groups can also react with Ca in gypsum slurry. 2+ Forming stable complexes and reducing free Ca 2+ The concentration of CaSO4·2H2O slows down the crystallization process of gypsum. This complexation effect slows down the hydration reaction rate of gypsum and prolongs the setting time of gypsum.

[0024] The beneficial technical effects of the present invention are as follows: This invention provides a method for preparing a bifunctional gypsum admixture based on plant polyphenol nanoparticles. The bifunctional gypsum admixture is obtained by coating plant tannins onto the surface of metal oxide nanoparticles and assembling core-shell structured nanoparticles with another metal ion coordinated on the tannic acid coating layer. The provided preparation method is simple, operates under mild conditions, is easy to scale up, and is convenient, efficient, and multifunctional.

[0025] The bifunctional gypsum admixture provided by this invention can delay the setting time of gypsum and increase the plasticity time of gypsum slurry. After introducing this admixture at 10% to 50% of the gypsum mass, the initial setting time of gypsum is extended to 20 to 70 minutes. At the same time, the assembly of the core-shell structure fully utilizes the synergistic effect of the two high-Z elements to achieve efficient shielding of X-rays by gypsum. It also solves the problem that metal oxide nanoparticles are difficult to load uniformly and stably onto gypsum crystals. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 SEM images of gypsum samples with different proportions of gypsum admixtures from Examples 1 and 3, and blank gypsum samples.

[0028] Figure 2 Fourier transform infrared spectrum (a) of erbium oxide nanoparticles and gypsum admixture prepared in Example 1, high-resolution X-ray photoelectron spectrum (O 1s) of gypsum admixture prepared in Example 1, X-ray diffraction pattern (c) of erbium oxide nanoparticles and gypsum admixture prepared in Example 1, and TSI value (d) of erbium oxide nanoparticles and gypsum admixture prepared in Example 1 dispersed in water for three hours.

[0029] Figure 3 The images show BF-TEM and elemental mapping images of the gypsum admixture prepared in Example 1.

[0030] Figure 4 The images show BF-TEM and elemental mapping images of the gypsum admixture prepared in Example 4.

[0031] Figure 5 This is a schematic diagram of an X-ray shielding efficiency testing device.

[0032] Figure 6The X-ray shielding efficiency of gypsum with added gypsum additives prepared in Examples 1 to 6 is given, where a is Example 1, b is Example 2, c is Example 3, d is Example 4, e is Example 5, and f is Example 6.

[0033] Figure 7 The X-ray shielding efficiency of the gypsum with the gypsum additives prepared in Example 1 and Comparative Example 1 is given, where a is the addition amount of 10%, b is the addition amount of 30%, and c is the addition amount of 50%.

[0034] Figure 8 The X-ray shielding efficiency of the gypsum with the gypsum additives prepared in Example 1 and Comparative Example 2 is given, where a is the addition amount of 10%, b is the addition amount of 30%, and c is the addition amount of 50%.

[0035] Figure 9 The X-ray shielding efficiency of the gypsum with the gypsum additives prepared in Example 5 and Comparative Example 3 is given, where a is the addition amount of 10%, b is the addition amount of 30%, and c is the addition amount of 50%.

[0036] Figure 10 The X-ray shielding efficiency of gypsum with 30% of the gypsum additives prepared in Example 1 and Comparative Example 4 was determined. Detailed Implementation

[0037] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.

[0038] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0039] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, are also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0040] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar to or equivalent to those described herein may be used in the implementation or testing of this invention.

[0041] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0042] Unless otherwise specified, room temperature in this invention refers to a temperature of 20±10℃.

[0043] Example 1 The preparation steps of gypsum admixtures based on core-shell structured nanoparticles are as follows: S1. Add 50g of 50nm nano-erbium oxide to the reactor, then add 1000mL of deionized water, and ultrasonically stir for 30min at room temperature to obtain a nano-erbium oxide dispersion. S2. Add 15 mmol of tannic acid to the reaction vessel in step S1, then heat to 60°C and stir at 2000 r / min for 2 h. After the reaction in step S2 is completed, 60 mmol of barium chloride dihydrate is added to the reaction vessel, and the pH of the reaction system is adjusted to 6.5 using a 0.1 M NaOH solution. The reaction is then stirred at 2000 r / min for 10 h at 60 °C. After the reaction is completed, the product is filtered, and then washed twice with deionized water to remove unloaded tannic acid and barium ions. Finally, the product is vacuum dried at 60 °C for 12 h to obtain the gypsum additive.

[0044] Example 2 The only difference from Example 1 is that 60 mmol of barium chloride dihydrate is replaced with 30 mmol of barium chloride dihydrate.

[0045] Example 3 The only difference from Example 1 is that 15 mmol of tannic acid was replaced with 30 mmol of tannic acid.

[0046] Example 4 Compared with Example 1, the only difference is that the stirring reaction temperature in steps S2 and S3 is adjusted from 60°C to 40°C.

[0047] Example 5 Compared with Example 1, the only difference is that 50g of 50nm nano-erbium oxide is replaced with 50g of 50nm nano-bismuth oxide.

[0048] Example 6 The only difference from Example 1 is that 60 mmol of barium chloride dihydrate is replaced with 60 mmol of tin chloride pentahydrate.

[0049] Comparative Example 1 Compared with Example 1, the only difference is that after the nano-erbium oxide reacts with tannic acid, it is filtered, washed, and dried to obtain the gypsum additive.

[0050] Comparative Example 2 Compared with Example 1, the only difference is that the stirring reaction temperature in steps S2 and S3 is adjusted from 60°C to 20°C, the reaction time in step S2 is 1 hour, and the reaction time in step S3 is 2 hours.

[0051] Comparative Example 3 Compared with Example 5, the only difference is that after the nano-bismuth oxide reacts with tannic acid, it is filtered, washed, and dried to obtain the gypsum additive.

[0052] Comparative Example 4 The only difference from Example 1 is that the gypsum additive is prepared by physically mixing nano-erbium oxide and barium chloride dihydrate in the same molar ratio as in Example 1.

[0053] Test case The retarding properties of the gypsum admixtures prepared in Examples 1-6 and Comparative Examples 1-3 were tested.

[0054] Initial setting time, compressive strength and flexural strength were determined in accordance with GB / T 17669.4-1994 "Determination of Physical Properties of Building Gypsum Paste".

[0055] The gypsum additives obtained in Examples 1-6 and Comparative Examples 1-4 were used in the preparation of X-ray shielding gypsum, as follows: 10%, 20%, 30%, 40%, and 50% of the additives (based on the mass of X-ray shielding plaster) were dispersed in 30% deionized water (based on the sum of the mass of plaster powder and additives). The mixture was then thoroughly mixed with the plaster powder to form a plaster slurry. The slurry was then poured into a mold with a diameter of 8 cm and a thickness of 5 mm and allowed to solidify completely to obtain plaster samples. The initial setting time of the plaster slurry was recorded, and the compressive strength and X-ray shielding performance of the plaster samples were tested.

[0056] The method for preparing blank plaster samples is as follows: Take an appropriate amount of gypsum powder and pour it into 30% deionized water (based on the mass of gypsum powder). Mix thoroughly to make gypsum slurry, then pour it into a mold with a diameter of 8cm and a thickness of 5mm and wait for it to solidify completely to obtain a blank gypsum sample.

[0057] In the experimental example, the X-ray shielding performance of gypsum material was evaluated by shielding efficiency, and the calculation method is shown in equation (1): ; Where AE is the X-ray shielding efficiency of the gypsum material, %; D0 is the initial X-ray dose, μGy / s; D πThe remaining X-ray dose after passing through the shielding material is expressed in μGy / s.

[0058] The X-ray emitting device used to test the shielding performance of gypsum materials was a UndowsE dosimeter. The energy range of the effective X-ray photons tested was 33–100 keV. This radiation voltage was referenced to the national standard JJG 393-2003 and the international standard ISO 4037-1:1996. The testing apparatus is as follows: Figure 5 As shown in Table 1, the test results for initial setting time are shown in Table 2, and the test results for flexural strength are shown in Table 3.

[0059] Table 1. Initial setting time (min) of gypsum under different admixture dosages As shown in Table 1, the retarding effect of the gypsum admixture provided by this invention is mainly affected by the dosage and reaction conditions. Specifically, the retarding effect of the gypsum admixtures in Examples 1-6 and Comparative Examples 1-3 on gypsum increases with increasing dosage, extending the initial setting time of gypsum to a maximum of 80 minutes. Due to differences in dosage and reaction conditions, Examples 1-6 and Comparative Examples 1-3 exhibit different retarding effects. This difference is mainly caused by the different content of phenolic hydroxyl groups on the surface of the nanoparticles. The content of phenolic hydroxyl groups directly affects the binding with free calcium ions in the gypsum system, thus affecting the retarding effect. Specifically, compared with Example 1, the retarding effect of Comparative Example 1 is enhanced to a certain extent. This is because the nanoparticles of Comparative Example 1 do not coordinate another metal ion through the phenolic hydroxyl groups of tannic acid on their surface. This results in a higher content of phenolic hydroxyl groups on the surface of the nanoparticles of Comparative Example 1 than that of Example 1, allowing them to bind more free calcium ions in the gypsum system. In addition, compared with Example 1, the retarding effect of Comparative Example 2 was significantly reduced. This is because the reaction temperature during the preparation of Comparative Example 2 was 20°C, and the total reaction time was 3 hours. The insufficient reaction temperature and time resulted in insufficient reaction between tannic acid and nanoparticles, and only a small amount of tannic acid covered the surface of the nanoparticles. Compared with Example 5, the retarding effect of Comparative Example 3 was enhanced to some extent. This is also because the surface of the nanoparticles in Comparative Example 3 did not coordinate another metal ion through the phenolic hydroxyl groups of tannic acid.

[0060] Table 2. Compressive strength (MPa) of gypsum under different admixture dosages Table 3. Flexural strength (MPa) of gypsum under different admixture dosages According to the compressive strength test results in Table 2 and the flexural strength test results in Table 3, the compressive strength of the blank gypsum is 21.5 MPa and the flexural strength is 7.3 MPa. Overall, after adding the gypsum additives from Examples 1-6 and Comparative Examples 1-3, the flexural and compressive strength of the gypsum decreased with increasing addition amount. This is because the additives achieve retarding by binding free calcium ions in the gypsum system, thus inhibiting the hydration of hemihydrate gypsum and the formation of dihydrate gypsum. However, they also inhibit the formation of a dense crystalline structure by interweaving gypsum crystals to a certain extent, thereby reducing the mechanical strength of the gypsum. In addition, because nanoparticles have nanoscale dimensions, they can fill the pores between gypsum crystals to a certain extent, thereby improving the density of gypsum crystals and enhancing the mechanical strength of the gypsum. Therefore, the gypsum additives provided by this invention exhibit excellent retarding performance for gypsum while ensuring high mechanical strength.

[0061] Figure 1 SEM images of gypsum samples with different proportions of gypsum admixtures from Examples 1 and 3, and blank gypsum samples. Figure 1 As shown, compared to blank gypsum, the addition of 10% of the gypsum admixtures from Examples 1 and 3 resulted in a denser gypsum crystal morphology due to the filling of nanoparticles. After adding 30% of the gypsum admixtures from Examples 1 and 3, the increased retarding effect made it difficult for the gypsum crystals to form a dense, long-needle-shaped structure, instead forming a short, thick, blocky structure.

[0062] Figure 2 In Figure 2a, 'a' represents the Fourier transform infrared spectrum of erbium oxide nanoparticles and the gypsum admixture (Ba-TA@Er2O3) prepared in Example 1. As shown in Figure 2a, the vibrational peaks of the functional groups corresponding to tannic acid molecules appeared in the spectrum of the gypsum admixture in Example 1.

[0063] Figure 2 In Figure 2b, the X-ray photoelectron spectroscopy (XPS) of the gypsum admixture prepared in Example 1 is a high-resolution spectrum of O 1s. As shown in Figure 2b, in addition to the Er-O inherent in the erbium oxide nanoparticles and the C-OH in the tannic acid molecules, CO-Ba appears at 533.22 eV. This indicates that the phenolic hydroxyl groups of the tannic acid coated on the surface of the nanoparticles are coordinated with barium ions, proving the successful assembly of the core-shell structure.

[0064] Figure 2 In Figure 2, c represents the X-ray diffraction pattern of erbium oxide nanoparticles and the gypsum additive prepared in Example 1. As shown in Figure 2, c, the diffraction peaks corresponding to Ba-TA@Er2O3 did not change or shift significantly compared to erbium oxide nanoparticles, indicating that the Ba-TA shell is an amorphous structure and does not change the crystal morphology of the nanoparticles after coating.

[0065] Figure 2In the figure, d represents the TSI (stability index) value of erbium oxide nanoparticles and the gypsum additive prepared in Example 1 after being dispersed in water for three hours. As shown in d in 2, the TSI value of Ba-TA@Er2O3 in water is significantly lower than that of erbium oxide nanoparticles, indicating that it has excellent dispersibility and stability in water.

[0066] Figure 3 and Figure 4 The images show BF-TEM and elemental mapping images of the gypsum admixtures prepared in Examples 1 and 4, respectively. Figures 3-4 As shown, the gypsum additives prepared in Examples 1 and 4 both formed a uniform and stable core-shell structure, with the barium element mapping image uniformly surrounding the erbium element. Relatively speaking, due to the higher reaction temperature and longer reaction time in Example 1, the nanoparticles prepared had better dispersion and a more uniform core-shell structure.

[0067] Figure 5 This is a schematic diagram of an X-ray shielding efficiency testing device.

[0068] Figure 6 The X-ray shielding efficiency of gypsum with the gypsum additives prepared in Examples 1-6 was determined, where a represents Example 1, b represents Example 2, c represents Example 3, d represents Example 4, e represents Example 5, and f represents Example 6. Figure 6It can be seen that the gypsum with the gypsum admixture of Example 1 has excellent X-ray shielding performance, with a shielding efficiency of over 60% for X-rays of 33–100 keV, and the shielding efficiency can reach over 90% when the addition amount is above 30%. Compared with Example 1, the shielding efficiency of the gypsum admixture of Example 2 is reduced to some extent, by about 2%–3% overall. This is because the amount of barium in the gypsum admixture of Example 2 is lower than that of Example 1, resulting in a lower barium content in the shell layer of the assembled core-shell structure. The shielding efficiency of the gypsum admixture of Example 3 is comparable to that of Example 1, indicating that excessive tannic acid does not affect the shielding efficiency of the material, but only affects the retarding effect of the gypsum. The shielding efficiency of the gypsum admixture of Example 4 is about 3%–4% lower than that of Example 1 overall. This is because the reaction temperature and reaction time of Example 4 are lower, and the tannic acid molecules in the shell layer cannot fully coordinate with barium ions or some tannic acid cannot fully coat the surface of erbium oxide nanoparticles. This shows that sufficient reaction conditions are a key factor affecting the quality of the core-shell structure of nanoparticles. Compared to Example 1, the core-shell structure of the gypsum admixture in Example 5 uses bismuth oxide nanoparticles as the substrate, but its overall shielding efficiency is lower than that of Example 1. This is because bismuth and erbium have different absorption edges; bismuth has lower absorption efficiency for X-ray photons in the 33–100 keV range than erbium. The core-shell structure of the gypsum admixture in Example 6 uses tin as the shell, resulting in excellent overall shielding efficiency, but still lower than that of Example 1. This indicates that the synergistic effect of erbium and barium is superior to that of erbium and tin.

[0069] Figure 7 The X-ray shielding efficiency of gypsum with the gypsum additives prepared in Example 1 and Comparative Example 1 is given, where a represents an addition amount of 10%, b represents an addition amount of 30%, and c represents an addition amount of 50%. Figure 7 It can be seen that the shielding efficiency of the gypsum admixture in Example 1 is significantly higher than that in Comparative Example 1. The gypsum admixture in Comparative Example 1, through modification with tannic acid, improves the dispersibility and stability of nanoparticles in the gypsum system, thereby enhancing the shielding performance of the material by increasing the probability and frequency of collisions between X-ray photons and nanoparticles. In contrast, the gypsum admixture in Example 1 introduces barium, which assembles with erbium oxide nanoparticles into a core-shell structure. This fully leverages the synergistic effect of the two elements while maintaining excellent dispersibility, thus further improving the shielding performance of the gypsum.

[0070] Figure 8 The X-ray shielding efficiency of gypsum with the gypsum additives prepared in Example 1 and Comparative Example 2 was calculated, where a represents an addition amount of 10%, b represents an addition amount of 30%, and c represents an addition amount of 50%. Figure 8 It can be seen that there is a significant difference in shielding efficiency between Comparative Example 2 and Example 1 gypsum additives. This indicates that the reaction conditions of Comparative Example 2 cannot assemble the two elements into a core-shell structure, thus failing to give full play to the synergistic effect of the complementary absorption edges of the two elements.

[0071] Figure 9 The X-ray shielding efficiency of gypsum with the gypsum additives prepared in Example 5 and Comparative Example 3 was calculated, where a represents an addition amount of 10%, b represents an addition amount of 30%, and c represents an addition amount of 50%. The comparison between the gypsum additives in Example 5 and Comparative Example 3 also demonstrates that, under the synergistic effect of the two elements, the shielding efficiency of gypsum is significantly higher than that of a single element.

[0072] Figure 10 The X-ray shielding efficiency of gypsum with 30% of the gypsum additives prepared in Example 1 and Comparative Example 4 was determined. Figure 10 The results show that, across the entire energy range of 33–100 keV, the shielding efficiency of the gypsum admixture in Example 1 is higher than that in Comparative Example 4, and the advantages of the core-shell structure become more pronounced with increasing energy. This indicates that simply mixing two elements with complementary absorption edges cannot fully utilize their synergistic effect, and the collisions between X-ray photons and these two elements remain disordered. This results in an inaccurate match between photon energy and the absorption edges of the elements, leading to a low probability of efficient photon collisions. By assembling these two elements into a core-shell structure, X-ray photons can undergo multiple collisions within the core-shell structure, precisely matching the photon energy with the element absorption ratio, fully utilizing the synergistic effect between different high-Z elements, and achieving efficient attenuation and absorption of X-ray photon energy.

[0073] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for preparing a bifunctional gypsum admixture, characterized in that, Includes the following steps: Plant tannins were added to a metal oxide nanoparticle dispersion, and after stirring and reacting, another metal element ion was added and the pH was adjusted to 6.5-7.

5. After stirring and reacting, the bifunctional gypsum admixture was obtained. The metal oxide nanoparticles include: erbium oxide nanoparticles, bismuth oxide nanoparticles, tungsten oxide nanoparticles, lanthanum oxide nanoparticles, tin oxide nanoparticles, or cesium oxide nanoparticles. The other metallic element ion includes: barium ion, tin ion or gadolinium ion.

2. The method for preparing the bifunctional gypsum admixture according to claim 1, characterized in that, The particle size of the metal oxide nanoparticles is 50–200 nm.

3. The method for preparing the bifunctional gypsum admixture according to claim 1, characterized in that, The content of metal oxide nanoparticles in the metal oxide nanoparticle dispersion is 5wt% to 10wt%; and / or, the dispersant of the metal oxide nanoparticle dispersion is water.

4. The method for preparing the bifunctional gypsum admixture according to claim 1, characterized in that, The plant tannins include one or more of tannic acid, gallic acid, and catechins.

5. The method for preparing the bifunctional gypsum admixture according to claim 1, characterized in that, The concentration of the plant tannin in the reaction system is 15–30 mmol / L; and / or, the concentration of the other metal element ion in the reaction system is 30–60 mmol / L.

6. The method for preparing the bifunctional gypsum admixture according to claim 1, characterized in that, After adding the plant tannin, the stirring speed of the reaction was 1500-2000 r / min, the reaction temperature was 40-60℃, and the reaction time was 1-2 h.

7. The method for preparing the bifunctional gypsum admixture according to claim 1, characterized in that, After adjusting the pH value, the stirring speed of the reaction was 1500-2000 r / min, the reaction temperature was 40-60℃, and the reaction time was 6-10 h.

8. A bifunctional gypsum admixture prepared by the preparation method of the bifunctional gypsum admixture according to any one of claims 1 to 7.

9. The application of the bifunctional gypsum admixture of claim 8 in the preparation of X-ray shielding gypsum.

10. An X-ray shielding plaster, characterized in that, The components, by weight percentage, comprise: 50% to 90% gypsum powder and 10% to 50% of the bifunctional gypsum additive as described in claim 8.

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