A method for preparing a bismuth molybdate / tourmaline functional composite material by a hydrothermal method

Abstract

This invention discloses a hydrothermal method for preparing Bi₂MoO₆ / tourmaline functional composite materials, belonging to the field of functional materials technology. The preparation method of the Bi₂MoO₆ / tourmaline functional composite material of this invention is as follows: Molybdenum source and bismuth source are added to deionized water to prepare solution A and solution B, respectively; tourmaline powder is added to deionized water to prepare suspension C; solution B is added dropwise to solution A and stirred, then suspension C is added and stirred again to obtain mixture D; sodium hydroxide solution is added dropwise to mixture D to prepare mixture E; mixture E is transferred to a hydrothermal reactor, sealed for reaction, and cooled to obtain hydrothermal product F; hydrothermal product F is separated by suction filtration and washed to obtain wet filter cake G; wet filter cake G is dried to obtain solid H; solid H is ground to obtain the final product. The Bi₂MoO₆ / tourmaline functional composite material prepared by this invention has high negative oxygen ion generation efficiency and environmental adaptability, and can still maintain high-efficiency release capacity in low humidity or light-free environments.

Description

Technical Field

[0001] This invention relates to the field of functional materials technology, and in particular to a method for preparing Bi2MoO6 / tourmaline functional composite materials by hydrothermal method. Background Technology

[0002] With the increasing airtightness of modern buildings and the diversification of indoor pollution sources (such as formaldehyde and benzene released from decoration materials, and electromagnetic radiation from household appliances), the natural concentration of negative oxygen ions in the air can no longer meet the needs of human health. Studies have shown that long-term exposure to low-negative-ion environments can easily lead to symptoms of "air conditioning sickness" (such as dizziness, fatigue, and respiratory discomfort), decreased concentration, and irritability, and may even induce fatigue syndrome and weakened immunity. As an important indicator of air cleanliness and biological activity, research on materials that release negative oxygen ions can not only reconstruct healthy microenvironments similar to natural ecosystems such as forests, waterfalls, and beaches by ionizing water molecules and pollutants in the air, but also improve respiratory health from the source through mechanisms such as neutralizing positive ions and settling PM2.5 and volatile organic compounds (VOCs). Furthermore, the release of negative oxygen ions can promote human cell metabolism, regulate the function of the autonomic nervous system, and indirectly improve sleep quality and psychological comfort. Developing efficient and long-lasting negative oxygen ion functional materials is not only a key technological path to promote the upgrading of human living environment towards ecology and health, but also an urgent need to address the deterioration of air quality in the process of urbanization and to build a sustainable and healthy lifestyle.

[0003] As a negative oxygen ion releasing material with significant research value, tourmaline belongs to the trigonal crystal system of cyclic silicate minerals. Its crystal structure is formed by the asymmetric coordination of silicon-oxygen tetrahedral rings with metal cations (such as iron, magnesium, and aluminum), exhibiting significant ion arrangement asymmetry along the c-axis. This structural feature allows it to spontaneously generate a stable built-in electric field (up to 10⁻⁶) even without an external electric field or temperature stimulation. 4 -10 7 V / m), forming a permanent electric dipole moment. This property allows it to continue acting on water molecules in the air even in the absence of light and power, generating highly reactive negative oxygen ions (such as O2) through ionization reactions. - ·(H2O)n、OH - ·(H2O)n), and is therefore known as a "natural negative oxygen ion generator", showing broad application prospects in air purification, functional textiles, healthy building materials and other fields.

[0004] However, while tourmaline possesses the ability to spontaneously polarize and release negative oxygen ions, its practical application still faces numerous challenges: in low-humidity environments, the release efficiency of negative ions decreases significantly due to the lack of sufficient water molecules participating in the ionization process; the released ion concentration is generally low, making it difficult to meet the requirements of high-cleanliness spaces; powder particles are prone to agglomeration, leading to a reduction in effective specific surface area and masking of active sites; the surface is easily deactivated by adsorbing pollutants from the air, limiting long-term stability; and its effective range is narrow, typically detectable only within 20 cm of the material surface. Therefore, overcoming these bottlenecks has become a key scientific issue in improving the functional performance of tourmaline.

[0005] To enhance the negative oxygen ion release capacity of tourmaline, researchers have conducted various explorations. Traditional modification strategies include particle size control, surface coating, and doping with rare earth elements (such as Ce and La). Studies have shown that while reducing particle size can increase specific surface area, excessive grinding can introduce lattice defects and weaken spontaneous polarization intensity. The introduction of rare earth ions can, however, adjust the Fe... 2+ / Fe 3+ Valence equilibrium is achieved, optimizing the internal electric dipole moment of the crystal, thereby enhancing the surface electric field strength and negative oxygen ion yield. Furthermore, by constructing composite carriers such as porous ceramics or glazed tiles, the contact area between the material and air can be increased, significantly improving release efficiency.

[0006] Building upon this foundation, researchers have recently turned their attention to the design of semiconductor composite systems. Bismuth molybdate (Bi₂MoO₆) is a visible-light-responsive semiconductor material with a layered perovskite structure. Its alternating stacked Bi₂O₂ and MoO₄ layers endow it with high electron mobility and excellent photogenerated carrier separation capabilities. With the rise of semiconductor-mineral composite strategies, combining bismuth molybdate (Bi₂MoO₆) with tourmaline to construct heterostructure systems represents a highly promising synergistic enhancement pathway.

[0007] Therefore, how to combine bismuth molybdate (Bi2MoO6) with tourmaline to prepare a high-performance, multifunctional air purification material with stronger negative oxygen ion release function than tourmaline alone and suitable for complex environments is a problem that needs to be solved. Summary of the Invention

[0008] To address the above shortcomings, this invention provides a hydrothermal method for preparing Bi2MoO6 / tourmaline functional composite materials, which solves the problems of weak negative oxygen ion release function and susceptibility to environmental influences of tourmaline alone. The specific technical solution is as follows: A method for preparing Bi2MoO6 / tourmaline functional composite materials by hydrothermal method includes the following steps: (1) Add molybdenum source to deionized water and stir continuously for 1-2 h to obtain solution A; add bismuth source to deionized water and stir continuously for 1-4 h to obtain solution B; add tourmaline powder to deionized water and stir continuously for 0.5-2 h to obtain suspension C; (2) Slowly add solution B to solution A and stir for 10-25 min, then add suspension C and continue stirring for 0.1-0.4 h to obtain mixture D; (3) Add sodium hydroxide solution dropwise to the mixture D, and control the pH to 6-9 to obtain mixture E; (4) The mixture E is transferred to a hydrothermal reactor lined with polytetrafluoroethylene, sealed and placed in an oven for reaction. After the reaction is completed, it is naturally cooled to room temperature to obtain hydrothermal product F. (5) After separating the hydrothermal product F by vacuum filtration, the filter cake is washed three times each with deionized water and anhydrous ethanol to obtain wet filter cake G. (6) The wet filter cake G is placed in a drying oven and dried to obtain solid H. The solid H is ground for 20-40 min to obtain product I, which is the Bi2MoO6 / tourmaline functional composite material.

[0009] Preferably, in step (1), the molybdenum source is ammonium molybdate tetrahydrate; the bismuth source is bismuth nitrate pentahydrate; and the tourmaline powder is white tourmaline powder.

[0010] Preferably, in step (1), the molar ratio of the bismuth source to the molybdenum source is n(Bi): n(Mo) = 1:(0.5-2), and the amount of tourmaline powder added is 1-2 times the mass of the bismuth source.

[0011] Preferably, in steps (1) and (2), the stirring is carried out at room temperature.

[0012] Preferably, in step (3), the concentration of the sodium hydroxide solution is 0.5-2 mol / L.

[0013] Preferably, in step (4), the reaction temperature is 120-180℃ and the reaction time is 6-15 h.

[0014] Preferably, in step (6), the drying temperature is 60-100℃ and the drying time is 3-6 h.

[0015] The present invention also provides a Bi2MoO6 / tourmaline functional composite material prepared by the above preparation method.

[0016] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention constructs a heterocomposite structure of tourmaline and bismuth molybdate (Bi2MoO6) by hydrothermal method, realizing the synergistic effect of spontaneous polarization and photogenerated carrier separation. The photogenerated electrons generated by bismuth molybdate under visible light can effectively enhance the ionization ability of water molecules by the electric field on the surface of tourmaline, and significantly improve the generation efficiency and stability of negative oxygen ions.

[0017] 2. In this invention, the thin nanosheet structure of Bi2MoO6, when combined with tourmaline, forms a heterostructure that expands the range of light absorption, enhances electron transfer, and further strengthens the electric field strength inherent in tourmaline due to its spontaneous polarization. After the composite, the negative oxygen ion release performance of the Bi2MoO6 / tourmaline composite material is effectively improved.

[0018] 3. In this invention, bismuth molybdate has a layered perovskite structure and high electron mobility, which not only provides a good dispersion substrate for tourmaline and prevents particle agglomeration, but also promotes charge separation and prolongs carrier lifetime by forming a built-in heterojunction. This enables the composite material to have stronger environmental adaptability and the ability to continuously release negative oxygen ions under light conditions, that is, the composite material still has a high efficiency release capability in low humidity or lightless environments.

[0019] 4. The composite system of this invention combines the permanent polarization characteristics of tourmaline with the visible light response performance of bismuth molybdate, achieving efficient release of negative oxygen ions under low-energy conditions and wide range of conditions (such as low humidity and low light), and also has the function of photocatalytic degradation of organic pollutants, providing a reliable technical path for the development of multifunctional and long-lasting air purification materials. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 X-ray diffraction analysis pattern of the Bi2MoO6 / tourmaline functional composite material prepared in Example 1; Figure 2 A scanning electron microscope image at 5 μm of the Bi2MoO6 / tourmaline functional composite material prepared in Example 1; Figure 3 Comparison of negative ion release performance of Bi2MoO6 / tourmaline functional composite material, Bi2MoO6 material alone, and tourmaline material alone prepared in Example 1; Figure 4 The infrared spectrum of the Bi2MoO6 / tourmaline functional composite material prepared in Example 1. Detailed Implementation

[0022] The specific embodiments of the present invention are described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments. Unless otherwise defined, all technical terms used below have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing specific embodiments only and are not intended to limit the scope of protection of the present invention. Unless otherwise specifically stated, all raw materials, reagents, instruments, and equipment used in the present invention are commercially available or can be prepared by existing methods.

[0023] Example 1 This embodiment discloses a method for preparing Bi2MoO6 / tourmaline functional composite materials via a hydrothermal method, comprising the following steps: ①According to the molar ratio of bismuth (Bi), molybdenum (Mo), and the main cation in white tourmaline (n(Bi): n(Mo) = 1:0.5), the amount of white tourmaline powder added is 1 times the mass of the corresponding bismuth source. Weigh an appropriate amount of ammonium molybdate tetrahydrate, add deionized water, and stir continuously at room temperature for 1 h to obtain solution A with a concentration of 8.85 g / L; weigh the corresponding molar mass of bismuth nitrate pentahydrate, add deionized water, and stir continuously at room temperature for 1 h to obtain solution B with a concentration of 48.5 g / L; weigh an appropriate amount of white tourmaline powder, add deionized water, wherein the mass ratio of tourmaline powder to added deionized water is 1:15, and stir continuously at room temperature for 0.5 h to obtain suspension C; ② Slowly add solution B to solution A, stir and mix evenly, then add suspension C, and continue stirring at room temperature for 0.1 h to fully mix the components and obtain precursor mixture D; ③ Take about 10 mL of 0.5 mol / L sodium hydroxide solution and add it dropwise to the precursor mixture D, controlling its pH to 6, to obtain mixture E; ④ Transfer the precursor mixture E to a polytetrafluoroethylene-lined hydrothermal reactor, seal it, and place it in an oven. React at 120 °C for 6 h. After the reaction is complete, allow it to cool naturally to room temperature to obtain the hydrothermal product F. ⑤ The hydrothermal product F was separated by vacuum filtration, and the filter cake was washed three times each with deionized water and anhydrous ethanol to obtain wet filter cake G. ⑥ Place the wet filter cake G in a drying oven and dry it at 60 °C for 3 h to obtain the dried solid H. Grind the solid H thoroughly for 20 min to obtain product I, which is the Bi2MoO6 / tourmaline functional composite material.

[0024] The X-ray diffraction pattern of the Bi2MoO6 / tourmaline functional composite material prepared in this embodiment is shown in the figure below. Figure 1As shown, the horizontal axis represents the 2θ angle, and the vertical axis represents the diffraction peak intensity. Furthermore, Bi2MoO6 can accurately correspond to the Bi2MoO6 PDF#76-2388 card, indicating that Bi2MoO6 powder was successfully prepared.

[0025] The scanning electron microscope (SEM) image of the Bi2MoO6 / tourmaline functional composite material prepared in this embodiment at 5 μm is shown below. Figure 2 As shown in the figure, Bi2MoO6 is relatively uniformly dispersed around the tourmaline.

[0026] The infrared spectrum of the Bi2MoO6 / tourmaline functional composite material prepared in this embodiment is as follows: Figure 4 As shown in the figure, the characteristic peaks of the Mo-O-Mo bond of bismuth molybdate (~730 and ~840 cm⁻¹) and the characteristic peaks of the Si-O-Si bond of tourmaline (900-1200 cm⁻¹) coexist in the infrared spectrum, indicating that the structures of both remain intact.

[0027] Example 2 This embodiment discloses a method for preparing Bi2MoO6 / tourmaline functional composite materials via a hydrothermal method, comprising the following steps: ①According to the molar ratio of bismuth (Bi), molybdenum (Mo) to the main cations in white tourmaline (n(Bi): n(Mo) = 1:1), the amount of white tourmaline powder added is 1 times the mass of the corresponding bismuth source. Weigh an appropriate amount of ammonium molybdate tetrahydrate, add deionized water, and stir continuously at room temperature for 1 h to obtain solution A with a concentration of 14.12 g / L; weigh the corresponding molar mass of bismuth nitrate pentahydrate, add deionized water, and stir continuously at room temperature for 2 h to obtain solution B with a concentration of 48.5 g / L; weigh an appropriate amount of white tourmaline powder, add deionized water, wherein the mass ratio of tourmaline powder to added deionized water is 1:15, and stir continuously at room temperature for 1 h to obtain suspension C; ② Slowly add solution B to solution A, stir and mix evenly, then add suspension C, and continue stirring at room temperature for 0.2 h to fully mix the components and obtain precursor mixture D; ③ Take about 6 mL of 1 mol / L sodium hydroxide solution and add it dropwise to the precursor mixture D, controlling its pH to 7, to obtain mixture E; ④ Transfer the precursor mixture E to a polytetrafluoroethylene-lined hydrothermal reactor, seal it, and place it in an oven. React at 140 °C for 9 h. After the reaction is complete, allow it to cool naturally to room temperature to obtain the hydrothermal product F. ⑤ The hydrothermal product F was separated by vacuum filtration, and the filter cake was washed three times each with deionized water and anhydrous ethanol to obtain wet filter cake G. ⑥ Place the wet filter cake G in a drying oven and dry it at 70 °C for 4 h to obtain the dried solid H. Grind the solid H thoroughly for 30 min to obtain product I, which is the Bi2MoO6 / tourmaline functional composite material.

[0028] The negative ion release of the composite material prepared in this embodiment was measured to be 674 ions / cm³.

[0029] Example 3 This embodiment discloses a method for preparing Bi2MoO6 / tourmaline functional composite materials via a hydrothermal method, comprising the following steps: ①According to the molar ratio of bismuth (Bi), molybdenum (Mo) to the main cations in white tourmaline (n(Bi): n(Mo) = 1:1.5), the amount of white tourmaline powder added is twice the mass of the corresponding bismuth source. Weigh an appropriate amount of ammonium molybdate tetrahydrate, add deionized water, and stir continuously at room temperature for 2 h to obtain a solution A with a concentration of 17.67 g / L; weigh the corresponding molar mass of bismuth nitrate pentahydrate, and stir continuously at room temperature for 3 h to obtain a solution B with a concentration of 48.5 g / L; weigh an appropriate amount of white tourmaline powder, add deionized water, wherein the mass ratio of tourmaline powder to added deionized water is 1:15, and stir continuously at room temperature for 1.5 h to obtain a suspension C; ② Slowly add solution B to solution A, stir and mix evenly, then add suspension C, and continue stirring at room temperature for 0.3 h to fully mix the components and obtain precursor mixture D; ③ Take about 8 mL of 1.5 mol / L sodium hydroxide solution and add it dropwise to the precursor mixture D, controlling its pH to 8, to obtain mixture E; ④ Transfer the precursor mixture E to a polytetrafluoroethylene-lined hydrothermal reactor, seal it, and place it in an oven. React at 160 °C for 12 h. After the reaction is complete, allow it to cool naturally to room temperature to obtain the hydrothermal product F. ⑤ The hydrothermal product F was separated by vacuum filtration, and the filter cake was washed three times each with deionized water and anhydrous ethanol to obtain wet filter cake G. ⑥ Place the wet filter cake G in a drying oven and dry it at 90 ℃ for 5 h to obtain the dried solid H. Grind the solid H thoroughly for 35 min to obtain product I, which is the Bi2MoO6 / tourmaline functional composite material.

[0030] The negative ion release of the composite material prepared in this embodiment was tested to be 577 ions / cm³.

[0031] Example 4 This embodiment discloses a method for preparing Bi2MoO6 / tourmaline functional composite materials via a hydrothermal method, comprising the following steps: ①According to the molar ratio of bismuth (Bi), molybdenum (Mo) to the main cations in white tourmaline (n(Bi): n(Mo) = 1:2), the amount of white tourmaline powder added is twice the mass of the corresponding bismuth source. Weigh an appropriate amount of ammonium molybdate tetrahydrate, add deionized water, and stir continuously at room temperature for 2 hours to obtain solution A with a concentration of 20.3 g / L; weigh the corresponding molar mass of bismuth nitrate pentahydrate, add deionized water, and stir continuously at room temperature for 4 hours to obtain solution B with a concentration of 48.5 g / L; weigh an appropriate amount of white tourmaline powder, add deionized water, wherein the mass ratio of tourmaline powder to added deionized water is 1:15, and stir continuously at room temperature for 2 hours to obtain suspension C; ② Slowly add solution B to solution A, stir and mix evenly, then add suspension C, and continue stirring at room temperature for 0.4 h to fully mix the components and obtain precursor mixture D; ③ Take about 10 mL of 2 mol / L sodium hydroxide solution and add it dropwise to the precursor mixture D, controlling its pH to 9, to obtain mixture E; ④ Transfer the precursor mixture E to a polytetrafluoroethylene-lined hydrothermal reactor, seal it, and place it in an oven. React at 180 °C for 15 h. After the reaction is complete, allow it to cool naturally to room temperature to obtain the hydrothermal product F. ⑤ The hydrothermal product F was separated by vacuum filtration, and the filter cake was washed three times each with deionized water and anhydrous ethanol to obtain wet filter cake G. ⑥ Place the wet filter cake G in a drying oven and dry it at 100 °C for 6 h to obtain the dried solid H. Grind the solid H thoroughly for 40 min to obtain product I, which is the Bi2MoO6 / tourmaline functional composite material.

[0032] The negative ion release of the composite material prepared in this embodiment was tested to be 585 ions / cm³.

[0033] The negative ion release rates of the composite material from Example 1, the Bi2MoO6 material alone, and the tourmaline material alone were measured separately, with the negative ion release rate in the environment used as a reference. The results are as follows: Figure 3 As shown in the figure, the negative ion release of the composite material in Example 1 is 713 ions / cm³; the negative ion release of Bi₂MoO₆ material alone is 320 ions / cm³; and the negative ion release of tourmaline material alone is 377 ions / cm³. It is evident that the negative ion release performance of tourmaline composited with Bi₂MoO₆ in this invention is significantly improved compared to pure tourmaline.

[0034] To illustrate the effectiveness of the material in low-humidity environments, the applicant tested the negative oxygen ion release of each material under normal humidity conditions (50% relative humidity) and low humidity conditions (30% relative humidity), respectively. The results showed: Under conditions of 50% relative humidity, the negative oxygen ion release of pure tourmaline is 310-380 ions / cm³, while that of the composite material of the present invention (Examples 1-4) is 650-720 ions / cm³. Under low humidity conditions of 30% relative humidity, the release of pure tourmaline drops to 150-180 ions / cm³, while the release of the composite material of the present invention (Examples 1-4) can still reach 400-450 ions / cm³.

[0035] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A method for preparing Bi2MoO6 / tourmaline functional composite materials via hydrothermal method, characterized in that, Includes the following steps: (1) Add molybdenum source and bismuth source to deionized water and stir to obtain solution A and solution B respectively; add tourmaline powder to deionized water and stir to obtain suspension C; (2) Slowly add solution B to solution A while stirring, add suspension C and continue stirring to obtain mixture D; (3) Add sodium hydroxide solution dropwise to the mixture D, and control the pH to 6-9 to obtain mixture E; (4) Transfer the mixture E to a hydrothermal reactor, seal it, and place it in an oven to react. After the reaction is complete, allow it to cool naturally to room temperature to obtain the hydrothermal product F. (5) After separating the hydrothermal product F by vacuum filtration, the filter cake is washed to obtain a wet filter cake G; (6) The wet filter cake G is placed in a drying oven and dried to obtain solid H. The solid H is then ground thoroughly to obtain product I, which is the Bi2MoO6 / tourmaline functional composite material.

2. The method for preparing Bi2MoO6 / tourmaline functional composite material by hydrothermal method according to claim 1, characterized in that, In step (1), the molybdenum source is ammonium molybdate tetrahydrate; the bismuth source is bismuth nitrate pentahydrate; and the tourmaline powder is white tourmaline powder.

3. The method for preparing Bi2MoO6 / tourmaline functional composite material by hydrothermal method according to claim 1, characterized in that, In step (1), the molar ratio of the bismuth source to the molybdenum source is n(Bi): n(Mo) = 1:(0.5-2), and the amount of tourmaline powder added is 1-2 times the mass of the bismuth source.

4. The method for preparing Bi2MoO6 / tourmaline functional composite material by hydrothermal method according to claim 1, characterized in that, In steps (1) and (2), the stirring is carried out at room temperature.

5. The method for preparing Bi2MoO6 / tourmaline functional composite material by hydrothermal method according to claim 1, characterized in that, In step (3), the concentration of the sodium hydroxide solution is 0.5-2 mol / L.

6. The method for preparing Bi2MoO6 / tourmaline functional composite material by hydrothermal method according to claim 1, characterized in that, In step (4), the reaction temperature is 120-180℃ and the reaction time is 6-15 h.

7. The method for preparing Bi2MoO6 / tourmaline functional composite material by hydrothermal method according to claim 1, characterized in that, In step (6), the drying temperature is 60-100℃ and the drying time is 3-6 h.

8. A Bi2MoO6 / tourmaline functional composite material prepared by the preparation method according to any one of claims 1-7.

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