Method for preparing magnesium oxide
By using a combined hydrothermal treatment method with magnesium chloride, sodium carbonate, and surfactants, the problem of morphology control of mesoporous magnesium oxide was solved, and a high-efficiency, low-cost flower-shaped magnesium oxide was prepared, which is suitable for CO2 adsorption and wastewater treatment in the environmental protection field.
Patent Information
- Application Number
- CN202510531899.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-25
- Publication Date
- 2025-08-01
AI Technical Summary
Existing methods face challenges in terms of precise control of pore structure and cost-effectiveness in large-scale production when preparing mesoporous magnesium oxide, making it difficult to achieve effective control of morphology.
Magnesium oxide is prepared by mixing magnesium chloride and sodium carbonate solutions, adding a surfactant, and then performing hydrothermal and heat treatment. The specific steps include stirring, hydrothermal reaction, washing, and heat treatment, while controlling reaction conditions such as temperature and time.
Flower-shaped magnesium oxide was prepared, which has a large specific surface area and uniform pore size distribution. It has excellent material properties and relatively low cost, making it suitable for CO2 adsorption and wastewater treatment in the environmental protection field.
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Figure CN120398096A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of material preparation, and particularly relates to a method for preparing magnesium oxide. Background Art
[0002] As an important inorganic chemical product, magnesium oxide is increasingly used in CO2 adsorption in the environmental protection field, electrode materials for lithium-sulfur batteries, antibacterial materials, etc. Compared with bulk materials, the micro-morphology of materials not only has a great influence on their physical and chemical properties, but also can broaden their application fields. Therefore, spherical magnesium oxide, magnesium oxide nanotubes, bird's nest-shaped magnesium oxide, mesoporous magnesium oxide, and magnesium oxide thin films have emerged one after another, and their applications have been studied. Among them, mesoporous magnesium oxide has the characteristics of a large specific surface area, pore volume, and uniform pore size distribution, and has remarkable effects in environmental protection, such as adsorbing the increasing carbon dioxide in the air, removing fluoride ions in water, and heavy metal ions in wastewater, etc. In the preparation of mesoporous magnesium oxide, the template method is widely used. Some researchers have also used surfactants as soft templates, magnesium chloride as a magnesium source, and ammonia water as a precipitant to prepare mesoporous magnesium oxide, and the obtained morphology is flaky. However, existing methods still face challenges in terms of precise pore structure regulation, large-scale production, cost-effectiveness, etc., and it is necessary to further develop efficient and controllable synthesis strategies. Summary of the Invention
[0003] The technical problem to be solved by the present invention is: to provide a method for preparing magnesium oxide to solve the technical problem that the morphology of magnesium oxide cannot be regulated.
[0004] To achieve the above object, the technical solution adopted by the present invention is: to provide a method for preparing magnesium oxide, including the following steps: mixing a magnesium chloride solution and a sodium carbonate solution, then adding a surfactant and stirring for 20 - 40 min, and the mass ratio of magnesium chloride, sodium carbonate, and surfactant in the reaction system is 0.9 - 1.1:0.9 - 1.1:0.02 - 0.045; then raising the temperature of the reaction system to 170 - 190 °C, and carrying out hydrothermal treatment for 11 - 13 h, then washing and filtering, and placing the filtered product at 550 - 650 °C for heat treatment for 0.5 - 1.5 h to obtain magnesium oxide.
[0005] On the basis of the above technical solution, the present invention can also be improved as follows:
[0006] Further, the concentrations of both the magnesium chloride solution and the sodium carbonate solution are 0.15 - 0.25 mol / L.
[0007] Further, the surfactant is cetyltrimethylammonium bromide (CTAB) or sodium dodecylbenzenesulfonate (SDBS).
[0008] Furthermore, the mass ratio of magnesium chloride, sodium carbonate and surfactant is 0.95:1.06:0.03.
[0009] Furthermore, the hydrothermal temperature is 180 °C and the hydrothermal time is 12 h.
[0010] Furthermore, the washing liquid used for washing is water and / or ethanol.
[0011] Furthermore, the heating rate during heat treatment is 8 - 12 °C / min.
[0012] Furthermore, the heat treatment temperature is 600 °C and the heat treatment time is 1 h.
[0013] The beneficial effects of the present invention are as follows: The present invention prepares flower-shaped magnesium oxide by the soft template method. When the addition amount of SDBS is 2.5%, the specific surface area of the prepared flower-shaped magnesium oxide can reach 80.99 m 2 g -1 , the average pore diameter is 10.97 nm, and the pore volume is 0.22 m 3 g -1 ; when the addition amount of SDBS is 4%, the flower shape of magnesium oxide is the most complete. The raw materials used in the preparation of the present invention are relatively cheap and easily available, the preparation process is relatively simple, and it has the advantages of environmental protection, high efficiency, excellent material properties, excellent adsorption properties, etc., and also has broad application prospects and economic feasibility. BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Figure 1 XRD patterns of magnesium oxide prepared with different CTAB addition amounts;
[0015] Figure 2 Particle size distribution diagrams of magnesium oxide prepared with different CTAB addition amounts;
[0016] Figure 3 SEM images of magnesium oxide prepared with different CTAB addition amounts; wherein Figure (a) is the SEM image of magnesium oxide prepared when the CTAB addition amount is 7%, Figure (b) is the SEM image of magnesium oxide prepared when the CTAB addition amount is 8%, Figure (c) is the SEM image of magnesium oxide prepared when the CTAB addition amount is 9%, Figure (d) is the SEM image of magnesium oxide prepared when the CTAB addition amount is 10%, and Figure (e) is the SEM image of magnesium oxide prepared when the CTAB addition amount is 11%;
[0017] Figure 4 XRD patterns of magnesium oxide prepared with different SDBS addition amounts;
[0018] Figure 5 Particle size distribution diagrams of magnesium oxide prepared with different SDBS addition amounts;
[0019] Figure 6SEM images of magnesium oxide prepared with different amounts of SDBS; among them, Figure (a1) is a 5k magnification image of magnesium oxide prepared with 2% SDBS added, Figure (a2) is a 10k magnification image of magnesium oxide prepared with 2% SDBS added, Figure (b1) is a 5k magnification image of magnesium oxide prepared with 2.5% SDBS added, Figure (b2) is a 10k magnification image of magnesium oxide prepared with 2.5% SDBS added, Figure (c1) is a 5k magnification image of magnesium oxide prepared with 3% SDBS added, Figure (c2) is a 10k magnification image of magnesium oxide prepared with 3% SDBS added, Figure (d1) is a 5k magnification image of magnesium oxide prepared with 3% SDBS added, Figure (d2) is a 10k magnification image of magnesium oxide prepared with 3% SDBS added, Figure (e1) is a 5k magnification image of magnesium oxide prepared with 4% SDBS added, Figure (e2) is a 10k magnification image of magnesium oxide prepared with 4% SDBS added, Figure (f1) is a 5k magnification image of magnesium oxide prepared with 4.5% SDBS added, Figure (f2) is a 10k magnification image of magnesium oxide prepared with 4.5% SDBS added;
[0020] Figure 7 BET diagram of magnesium oxide prepared when the addition amount of SDBS is 2.5%;
[0021] Figure 8 Pore size distribution diagram of magnesium oxide prepared when the addition amount of SDBS is 2.5%. Detailed implementation manners
[0022] The following describes the detailed implementation manners of the present invention to facilitate those skilled in the art of this technology to understand the present invention. For those conditions not specified in the examples, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. For reagents or instruments not specified for the manufacturer, they are all conventional products that can be obtained through commercial purchase. However, it should be clear that the present invention is not limited to the scope of the detailed implementation manners. For those ordinary skilled in the art of this technology, as long as various changes are within the spirit and scope of the present invention defined and determined by the appended claims, these changes are obvious, and all inventions and creations using the concept of the present invention are within the scope of protection.
[0023] Example 1
[0024] A method for preparing magnesium oxide includes the following steps: Dissolve 0.95 g of magnesium chloride and 1.06 g of sodium carbonate in 50 mL of water respectively, then mix them evenly to obtain a MgCO3 suspension; Next, dissolve 0.09 g of cetyltrimethylammonium bromide (CTAB) in 10 mL of ethanol, and then dropwise add the PVA alcohol solution to the MgCO3 suspension. After the addition is completed, stir for 30 min to fully mix the three; Then raise the temperature of the reaction system to 180 °C and hydrothermal react for 12 h, then wash with water and ethanol in turn and filter; Place the filtrate in a muffle furnace, raise the temperature from room temperature to 600 °C at a heating rate of 10 °C / min, and perform heat treatment for 1 h to obtain magnesium oxide.
[0025] Example 2
[0026] A method for preparing magnesium oxide includes the following steps: Dissolve 0.9 g of magnesium chloride and 1.1 g of sodium carbonate in 50 mL of water respectively, then mix them evenly to obtain a MgCO3 suspension; Next, dissolve 0.8 g of cetyltrimethylammonium bromide (CTAB) in 10 mL of ethanol, and then dropwise add the CTAB alcohol solution to the MgCO3 suspension. After the addition is completed, stir for 20 min to fully mix the three; Then raise the temperature of the reaction system to 170 °C and hydrothermal react for 13 h, then wash with water and ethanol in turn and filter; Place the filtrate in a muffle furnace, raise the temperature from room temperature to 550 °C at a heating rate of 8 °C / min, and perform heat treatment for 1.5 h to obtain magnesium oxide.
[0027] Example 3
[0028] A method for preparing magnesium oxide includes the following steps: Dissolve 1.1 g of magnesium chloride and 0.9 g of sodium carbonate in 50 mL of water respectively, then mix them evenly to obtain a MgCO3 suspension; Next, dissolve 1 g of sodium dodecylbenzenesulfonate (SDBS) in 10 mL of ethanol, and then dropwise add the SDBS alcohol solution to the MgCO3 suspension. After the addition is completed, stir for 40 min to fully mix the three; Then raise the temperature of the reaction system to 190 °C and hydrothermal react for 11 h, then wash with water and ethanol in turn and filter; Place the filtrate in a muffle furnace, raise the temperature from room temperature to 650 °C at a heating rate of 12 °C / min, and perform heat treatment for 0.5 h to obtain magnesium oxide.
[0029] The following test instruments are used in the experiments:
[0030] 1. X-ray diffractometer (XRD)
[0031] Use the X-ray diffractometer produced by Bruker Co., Ltd. in Germany to test the prepared magnesium oxide sample. The scanning range is 5 - 80°, the scanning rate is 4° / min, the step size is 0.02, the voltage is 40 kV, and the current is 40 mA.
[0032] 2. Particle Size and Zeta Potential Analyzer
[0033] For the test experiment, anhydrous ethanol was used as the dispersant. The magnesium oxide sample powder was directly put into the dispersant, and a Nano-ZS90 particle size and zeta potential analyzer was used as the test instrument to measure the particle size of the sample.
[0034] 3. Scanning Electron Microscope (SEM)
[0035] Before scanning, the dried and ground magnesium oxide sample was put into a test tube and ethanol was added as the dispersant. The dispersed sample was placed on a silicon wafer for drying treatment. At an acceleration voltage of 3 kV, the magnification of the sample was 1.00K, 10.0K, 20.0K, 30.0K, and 50.0K respectively to obtain SEM images, and the crystal morphology structure, particle size, etc. of the magnesium oxide sample were observed.
[0036] Experimental Example 1: Influence of Different CTAB Dosages on Magnesium Oxide
[0037] The CTAB dosages were set to 7%, 8%, 9%, 10%, and 11% respectively, and the remaining preparation conditions were the same to obtain different magnesium oxide samples, and the samples were analyzed.
[0038] 1. XRD Analysis
[0039] The magnesium oxide samples were subjected to XRD analysis, and the results are shown in Table 1 and Figure 1 as follows.
[0040] Table 1 Peak Intensity and Full Width at Half Maximum of (200) Crystal Plane of Magnesium Oxide Prepared with Different CTAB Dosages
[0041] CTAB addition amount 7％ 8％ 9％ 10％ 11％ (200) crystal plane peak intensity 1912 1439 1380 1753 1966 (200) crystal plane full width at half maximum 0.782 0.880 0.928 0.877 0.698
[0042] Figure 1 The X-ray diffraction patterns of magnesium oxide prepared with different CTAB dosages are shown. The characteristic peaks in the patterns belong to the diffraction crystal planes of (111), (200), (220), (311), and (222), which indicates that the peaks in the figure are typical diffraction peaks of magnesium oxide, and the obtained product is relatively pure magnesium oxide. From Figure 1 and Table 1, it can be seen that when the CTAB dosage is 9%, the diffraction peak (200) of the sample has a weak peak intensity and a wide full width at half maximum, and the activity of magnesium oxide is better. With the change of the dosage, the intensity of the characteristic peak of magnesium oxide first decreases and then increases, indicating that the change of different CTAB dosages makes the activity of magnesium oxide first increase and then decrease. Therefore, the optimal CTAB dosage is 9%.
[0043] 2. Particle Size Analysis
[0044] The magnesium oxide samples were subjected to particle size analysis, and the results are as Figure 2As shown. It can be seen from the figure that the particle size distributions of the magnesium oxides prepared with CTAB addition amounts of 7%, 8%, and 11% are relatively concentrated, while those of the magnesium oxides prepared with CTAB addition amounts of 9% and 8% are relatively dispersed. The reason may be that agglomeration occurs between the particles at 8% and 9%, resulting in the non-concentration of the sample particle size. The particle sizes of other samples are mainly concentrated in the range of 200 - 1600 nm. The particle sizes of the magnesium oxides prepared under the conditions of CTAB addition amounts of 7%, 8%, 9%, 10%, and 11% are 955.6 nm, 605.6 nm, 355.5 nm, 955.2 nm, and 1623 nm respectively. By comparison, it is found that the particle size of the magnesium oxide prepared under the condition of a CTAB addition amount of 9% is the smallest. As the PVA addition amount increases, the particle size of the magnesium oxide first decreases and then increases, indicating that CTAB has a greater influence on the particle size. In summary, when using CTAB as a surfactant, to obtain magnesium oxide with a smaller particle size, the optimal CTAB addition amount is 9%.
[0045] 3. SEM Analysis
[0046] SEM analysis was performed on the magnesium oxides prepared with different CTAB addition amounts, and the results are as Figure 3 shown. Among them, Figure (a) is the SEM image of the magnesium oxide prepared when the CTAB addition amount is 7%, Figure (b) is the SEM image of the magnesium oxide prepared when the CTAB addition amount is 8%, Figure (c) is the SEM image of the magnesium oxide prepared when the CTAB addition amount is 9%, Figure (d) is the SEM image of the magnesium oxide prepared when the CTAB addition amount is 10%, and Figure (e) is the SEM image of the magnesium oxide prepared when the CTAB addition amount is 11%. When CTAB is 7% in Figure (a), the shape of the magnesium oxide is mainly a bird's nest-like structure, and the lamellae are inserted and stacked from the side to the center, with a messy morphology. In Figure (b), a layered stacking begins to form a complete cubic structure, and there are also obvious stacking marks on the sides of some cubes. The shape of Figure (c) is mainly a complete cubic structure formed by layered stacking, and the side stacking gradually becomes more complete. In Figure (d), some of the crystal grains are smaller, but there are also blocky magnesium oxides with a relatively flat shape. In Figure (d), there are still traces of side stacking in a small number of cubes. In Figure (e), the microscopic morphology of the magnesium oxide is an irregular polygon structure with a smooth surface, more regular stacking, and smoother layered stacking, but there are also missing corners, the thickness of the particles increases, and the particle spacing gradually decreases. In summary, as the CTAB addition amount increases, the morphology of the magnesium oxide gradually transforms from a bird's nest-like structure with layered stacking to an irregular cubic structure with a smooth surface, and they are all composed of stacked flaky magnesium oxides.
[0047] Experimental Example 2 Influence of Different SDBS Addition Amounts on Magnesium Oxide
[0048] The addition amounts of PVA were set to 7%, 8%, 9%, 10% and 11% respectively, and the remaining preparation conditions were the same, obtaining different magnesium oxide samples, and the samples were analyzed.
[0049] 1. XRD characterization and analysis
[0050] The magnesium oxide samples were analyzed by XRD, and the results are shown in Table 2 and Figure 4 as follows.
[0051] Table 2 Peak intensity of (200) crystal plane of magnesium oxide prepared with different addition amounts of SDBS
[0052] SDBS addition amount 2％ 2.5％ 3％ 3.5％ 4％ 4.5％ (200) crystal plane peak intensity 1830 1825 1489 1354 1380 1743 (200) crystal plane full width at half maximum 0.741 0.774 0.829 0.851 0.906 0.884
[0053] Figure 4 is the X-ray diffraction pattern of magnesium oxide prepared with different addition amounts of SDBS. The characteristic peaks in the pattern belong to the diffraction crystal planes of (111), (200), (220), (311) and (222), which indicates that the peaks in the figure are typical diffraction peaks of magnesium oxide, and the obtained product is relatively pure magnesium oxide. When the addition amount of STBS is 4%, the peak width is the widest and the activity of magnesium oxide is better. With the increase of the amount of SDBS, the intensity of the characteristic diffraction peak (200) of magnesium oxide shows a trend of first decreasing and then increasing. From Figure 4 and Table 2, it can be seen that when the addition amount of SDBS is 4%, the full width at half maximum (FWHM) is relatively large on the (311) crystal plane, the particle size is small, and the FWHM is wide, which proves that the crystallinity of the prepared magnesium oxide is low and the crystal activity is enhanced. While for other addition amounts, the peak intensity of the diffraction peak is relatively strong, the FWHM is relatively narrow, and the activity is low. With the change of the addition amount of SDBS, the activity of magnesium oxide first increases and then decreases, and reaches the highest at the addition amount of 4%, so the addition amount of SDBS is selected as 4%.
[0054] 2. Particle size analysis
[0055] The magnesium oxide samples were analyzed for particle size, and the results are as Figure 5As shown. It can be seen from the figure that the particle size distribution of the sample is relatively uniform, and the particle size of the prepared magnesium oxide sample mainly concentrates in the range of 0.900 - 3 μm. The particle sizes of magnesium oxide prepared under the conditions of SDBS addition amounts of 2%, 2.5%, 3%, 3.5%, 4% and 4.5% are 2.99 μm, 1.89 μm, 1.51 μm, 1.20 μm, 0.964 μm and 1.11 μm respectively. By comparison, it is found that the particle size of magnesium oxide prepared under the condition of 4% SDBS addition amount is the smallest. It can be seen that the addition amount of SDBS has a great influence on the particle size of magnesium oxide. With the increase of the SDBS addition amount, the particle size of magnesium oxide shows a trend of first decreasing and then increasing. The smaller the particle size, the larger the specific surface area, and the more adsorption sites on the particle surface, which is more conducive to adsorption. Therefore, the obtained average particle size is smaller. When the SDBS addition amounts are 2% and 2.5%, there is a small peak in the particle size distribution. The reason for this may be that a part of the flaky magnesium oxide does not stack on the flower-like magnesium oxide, so two distribution peaks appear during measurement. To sum up, when SDBS is used as a surfactant, in order to obtain magnesium oxide with a smaller particle size, the best SDBS addition amount is 4%.
[0056] 3. SEM Analysis
[0057] SEM analysis was carried out on the magnesium oxide prepared under different SDBS addition amounts, and the results are as Figure 6As shown in the figure, Figure (a1) is a 5k - magnification image of magnesium oxide prepared with 2% SDBS addition, Figure (a2) is a 10k - magnification image of magnesium oxide prepared with 2% SDBS addition, Figure (b1) is a 5k - magnification image of magnesium oxide prepared with 2.5% SDBS addition, Figure (b2) is a 10k - magnification image of magnesium oxide prepared with 2.5% SDBS addition, Figure (c1) is a 5k - magnification image of magnesium oxide prepared with 3% SDBS addition, Figure (c2) is a 10k - magnification image of magnesium oxide prepared with 3% SDBS addition, Figure (d1) is a 5k - magnification image of magnesium oxide prepared with 3% SDBS addition, Figure (d2) is a 10k - magnification image of magnesium oxide prepared with 3% SDBS addition, Figure (e1) is a 5k - magnification image of magnesium oxide prepared with 4% SDBS addition, Figure (e2) is a 10k - magnification image of magnesium oxide prepared with 4% SDBS addition, Figure (f1) is a 5k - magnification image of magnesium oxide prepared with 4.5% SDBS addition, and Figure (f2) is a 10k - magnification image of magnesium oxide prepared with 4.5% SDBS addition. It can be seen from the SEM images that the shape of magnesium oxide prepared with SDBS as the surfactant is mainly a bird - nest - like structure. The lamellae insert and stack from the side to the center to fill it up, and the morphology is relatively disordered, with a radial length of about 0.5 - 3 μm. When the SDBS addition amounts are 2%, 2.5%, and 3% (Figures a1, a2, b1, b2, c1, and c2), the micro - morphology of magnesium oxide is an inward - concave bird - nest - like structure. The lamellae insert and stack from the side to the center to form a bird - nest - like structure with a relatively sunken middle, and most of the particles are about 0.5 - 3 μm. As the SDBS addition amount increases, the depression gradually decreases. When the SDBS addition amounts are 3.5% and 4% (Figures d1, d2, e1, and e2), the depression has greatly decreased, and the bird - nest - like structure is relatively complete, indicating that the lamellae stacking gradually increases; but when the SDBS addition amount is 4.5% (Figures f1 and f2), depressions appear again, and the particle spacing also increases. It shows that as the SDBS addition amount gradually increases, the morphology of magnesium oxide becomes more and more complete, and the morphology of magnesium oxide is the most complete at 4% and begins to show defects at 4.5%.
[0058] 4. BET Analysis
[0059] Figure 7 Figure is the BET diagram of magnesium oxide prepared when the SDBS addition amount is 2.5%. It can be seen from the figure that the specific surface area of the prepared magnesium oxide can reach 80.99 m 2 g -1 , the adsorption isotherm belongs to type IV, which is generally the adsorption isotherm of mesoporous materials. The hysteresis loop belongs to type H2(b). H2(b) is an ink - bottle - shaped mesoporous material with a relatively wide pore "neck". The H2(b) - type hysteresis loop also has pore blockage or percolation. From Figure 8It can be seen from the pore size distribution diagram that the pore size distribution of most magnesium oxides is in the range of 1 - 20 nm, the average pore size is 10.97 nm, and the total pore volume is 0.22 m 3 g -1 , indicating that the mesoporous material with a relatively concentrated pore size distribution can be prepared by the method of the present invention.
Claims
1. A method for preparing magnesium oxide, characterized in that, It includes the following steps: Mix the magnesium chloride solution and the sodium carbonate solution, then add a surfactant and stir for 20 - 40 min. The mass ratio of magnesium chloride, sodium carbonate and surfactant in the reaction system is 0.9 - 1.1:0.9 - 1.1:0.02 - 0.045; then raise the temperature of the reaction system to 170 - 190 °C, and carry out hydrothermal treatment for 11 - 13 h, then wash, filter, and place the filter residue at 550 - 650 °C for heat treatment for 0.5 - 1.5 h to obtain magnesium oxide.
2. The method for preparing magnesium oxide according to claim 1, wherein The concentrations of both the magnesium chloride solution and the sodium carbonate solution are 0.15 - 0.25 mol / L.
3. The method for preparing magnesium oxide according to claim 1, characterized in that, The surfactant is cetyltrimethylammonium bromide or sodium dodecylbenzenesulfonate.
4. The method for preparing magnesium oxide according to claim 1, characterized in that, The mass ratio of magnesium chloride, sodium carbonate and surfactant is 0.95:1.06:0.
03.
5. The method for preparing magnesium oxide according to claim 1, wherein The hydrothermal temperature is 180 °C and the hydrothermal time is 12 h.
6. The method for preparing magnesium oxide according to claim 1, characterized in that The washing liquid used for washing is water and / or ethanol.
7. The method for preparing magnesium oxide according to claim 1, wherein, The heating rate during the heat treatment is 8 - 12 °C / min.
8. The method for preparing magnesium oxide according to claim 1, wherein, The heat treatment temperature is 600 °C and the heat treatment time is 1 h.