A rotary hydrothermal method for extracting valuable metals from red mud to prepare functional oxides and construction of composite membranes and application thereof
Valuable metals were extracted from red mud using a rotary hydrothermal method, and γ-AlOOH hierarchical porous microspheres, Fe2O3 hierarchical porous microspheres, and TiO2 functional nano-oxides were prepared. This solved the problem of uneven mixing in the traditional static hydrothermal method and enabled efficient resource utilization and environmental remediation of red mud.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- QUFU NORMAL UNIV
- Filing Date
- 2023-11-16
- Publication Date
- 2026-05-29
AI Technical Summary
In the traditional static hydrothermal method for extracting valuable metals from red mud, the reaction system is not mixed evenly, resulting in the prepared functional materials having a wide particle size distribution, uneven morphology, and small specific surface area. In addition, it requires cumbersome additive processing, making it difficult to achieve green production.
Valuable metals were extracted from red mud using a rotating hydrothermal method. Al and Fe were separated by hydrochloric acid. γ-AlOOH hierarchical porous microspheres, Fe2O3 hierarchical porous microspheres, and TiO2 functional nano-oxides were prepared by rotating hydrothermal reaction. An organic-inorganic composite membrane was constructed, and the reaction efficiency was improved by using an axially rotating or radially mechanically stirred reactor.
The prepared functional materials have a narrower particle size distribution, more uniform morphology, and larger specific surface area, which improves adsorption performance and catalytic ability, and realizes efficient resource utilization and environmental governance of red mud.
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Figure CN117448581B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of materials and chemical engineering technology, and relates to a rotary hydrothermal method for extracting valuable metals from red mud to prepare functional oxides, as well as the construction of composite membranes and their applications. Background Technology
[0002] Red mud is a highly alkaline solid waste residue produced as a byproduct of alumina extraction in the aluminum industry. Its production has increased significantly with the surge in global demand for aluminum. my country remains the world's largest producer of alumina, producing 105 million tons of red mud in 2022 alone, but utilizing only 8 million tons. Red mud is typically dumped in the open, causing not only environmental pollution and water resource depletion but also soil degradation and ecological damage. Given the current severe situation, effectively addressing the environmental pollution caused by red mud while simultaneously comprehensively improving the high-value utilization of this low-value resource is of great significance.
[0003] Red mud is mainly composed of compounds of elements such as Al, Fe, Si, and Ti, as well as other mixed mineral phases and compounds containing trace elements such as Ni, Cd, K, and Pb. It is a valuable and abundant secondary resource, making the high-value utilization of its valuable elements an important research direction. For example, in patent application CN201410121083.X, Dong Hongjun et al. invented a method for comprehensively recovering valuable metals such as iron, aluminum, scandium, titanium, and vanadium from red mud. This method obtains products such as iron oxide, aluminum oxide, and metatitanic acid through magnetic separation and acid leaching. In patent application CN201510471341.1, Gu Mingyuan et al. invented a method and system for recovering valuable metals from red mud. This method obtains sodium oxide, iron products, and sodium aluminate products through methods such as adding reducing agents and calcining with quicklime. In the patent application number 202011589969.9, Liu Honghui et al. invented a method for the comprehensive recovery of valuable components in red mud. This method obtains sodium sulfate, iron oxide and aluminum oxide products by adding acid, mixing, roasting and extraction.
[0004] Furthermore, in the patent application CN201410121083.X, the applicant participated in the research on the preparation of active boehmite porous microspheres using red mud as raw material, which employed a traditional static hydrothermal method to extract aluminum from the red mud. However, the traditional static hydrothermal method, due to the static placement of the reactor without a stirring device, results in uneven mixing between the liquid and solid phases in the reaction system, leading to low heat-mass transfer efficiency. Consequently, the prepared functional materials often exhibit a wide particle size distribution, uneven morphology, and small specific surface area, severely restricting performance and subsequent applications. To improve this problem, various additives such as surfactants are often required, which in turn leads to cumbersome processing and is not conducive to green production. Summary of the Invention
[0005] Based on the above-mentioned technical problems to be solved, the present invention provides a rotary hydrothermal method for extracting valuable metals from red mud to prepare functional oxides, and the construction and application of composite membranes thereon.
[0006] To achieve the above objectives, the present invention adopts the following technical solution:
[0007] In a first aspect, this application provides a rotary hydrothermal method for extracting valuable metals from red mud to prepare functional oxides, the method comprising:
[0008] S01: Extract sodium aluminate solution, Fe-containing solid and Ti-containing solid from red mud.
[0009] To achieve more complete separation of Al and Fe in red mud, this application uses a high-concentration hydrochloric acid to mix with the red mud, thereby separating Al and Fe. Specifically, the red mud is mixed with hydrochloric acid at a concentration of 5.0-12.0 mol / L, heated to 80-100℃, and continuously stirred for 1.0-4.0 h to obtain a reaction mixture. The reaction mixture is then filtered through a Buchner funnel to obtain a supernatant containing Al and Fe and a solid containing Ti. Preferably, the concentration of hydrochloric acid is 5.0-8.0 mol / L, the heating temperature is 100℃, and the reaction time is 2.5 h.
[0010] The pH of the supernatant was adjusted to 11.0-12.2 using a 6.0 mol / L sodium hydroxide solution. After pH adjustment, the solution was stirred for 2.0 h to obtain a mixture. This mixture was then separated by suction filtration through a Buchner funnel to obtain a sodium aluminate solution and Fe-containing solids.
[0011] S02: The sodium aluminate solution and urea are mixed evenly and then subjected to a rotary hydrothermal reaction. After cooling to room temperature, the mixture is filtered to obtain γ-AlOOH hierarchical porous microspheres.
[0012] Sodium aluminate solution and urea with a concentration of 1.0 mol / L are stirred evenly and then placed into a reactor. A rotary hydrothermal reaction is carried out at 120-130℃ for 7.0-9.0 h. The rotary hydrothermal reaction involves the material rotating within the reactor and undergoing a hydrothermal reaction. The reactor can be an axially rotating homogeneous reactor, a reactor equipped with radial mechanical stirring, or a dynamic stirred tank reactor using axial compressed air stirring. After the rotary hydrothermal reaction is complete, the mixture is cooled to room temperature and separated by suction filtration through a Buchner funnel to obtain γ-AlOOH hierarchical porous microspheres. In this application, the rotation frequency of the reactor is controlled to control the product, resulting in a narrower particle size distribution, more uniform morphology, larger specific surface area, and superior application performance. If the rotation frequency is too high, the product particle size distribution becomes wider, the particle size increases, and the specific surface area decreases, leading to a decline in its application performance. Therefore, the rotation frequency of the homogeneous reactor in this application is 1-15 Hz, preferably 5-10 Hz.
[0013] S03: The Fe-containing solid was mixed with acid and then urea was added. After stirring evenly, a rotary hydrothermal reaction was carried out. After cooling to room temperature, the mixture was filtered to obtain Fe2O3 hierarchical porous microspheres.
[0014] Fe-containing solids are mixed with nitric acid, hydrochloric acid, or sulfuric acid at a concentration of 1.0-6.0 mol / L at a solid-liquid ratio of 1:30 to ensure that the iron in the Fe-containing solids exists in ionic form. Then, urea at a concentration of 1.0-3.0 mol / L is added and mixed to facilitate the redeposition of iron ions through the urea. The mixture is then placed in a reactor and subjected to a rotary hydrothermal reaction at a temperature of 110-200℃ and a rotation frequency of 1-15 Hz for 6.0-12.0 h. After the rotary hydrothermal reaction is complete, the mixture is cooled to room temperature and separated by suction filtration through a Buchner funnel to obtain Fe₂O₃ hierarchical porous microspheres. Preferably, the concentration of nitric acid, hydrochloric acid, or sulfuric acid is 2.0-5.0 mol / L, the concentration of urea is 1.0-2.0 mol / L, the rotary hydrothermal reaction temperature is 120-180℃, and the rotation frequency is 5-10 Hz.
[0015] S04: The Ti-containing solid is immersed in sulfuric acid, stirred, and filtered to obtain a titanium-rich liquid and solid A.
[0016] Ti-containing solid is mixed with 60-90% sulfuric acid at a solid-liquid ratio of 1:10 and stirred for 2.0-6.0 h. The mixture is then separated by suction filtration through a Buchner funnel to obtain a titanium-rich solution and solid A. Preferably, the stirring time is 3.0-5.0 h.
[0017] S05: After the titanium-rich liquid is mixed with ammonia water, TiO2-Ⅰ functional nano-oxide is obtained by co-precipitation at room temperature.
[0018] Ammonia solution with a concentration of 20-25% was added to a titanium-rich solution, and TiO2-Ⅰ functional nano-oxide was obtained by co-precipitation at room temperature. The amount of ammonia added was such that a suspension was formed. Preferably, the stirring time was 3.0-5.0 h.
[0019] S06: After mixing solid A with sodium hydroxide solution, the mixture is stirred and filtered to obtain solid B.
[0020] Solid A is mixed with a sodium hydroxide solution with a concentration of 2.0-7.0 mol / L at a solid-liquid ratio of 1:30 and stirred for 2.0-6.0 h. The mixture is then separated by suction filtration through a Buchner funnel to obtain solid B. Preferably, the concentration of the sodium hydroxide solution is 3.0-5.0 mol / L, and the stirring time is 3.0-5.0 h.
[0021] S07: The solid B is mixed with hydrofluoric acid and subjected to a rotary hydrothermal reaction. After cooling to room temperature, it is filtered to obtain TiO2-II functional nano-oxide.
[0022] Solid B is mixed with 20-40% hydrofluoric acid at a solid-liquid ratio of 1:15 and then placed in a reactor. The mixture is subjected to a rotary hydrothermal reaction at a temperature of 25-60℃ and a rotation frequency of 1-15Hz for 2.0-4.0 h. After the rotary hydrothermal reaction is complete, the mixture is cooled to room temperature and separated by suction filtration through a Buchner funnel to obtain TiO2-II functional nano-oxides. Preferably, the concentration of hydrofluoric acid is 25-35%, and the rotary hydrothermal reaction temperature is 30-50℃.
[0023] Secondly, this application provides an organic-inorganic composite membrane, wherein the inorganic additives in the preparation of the composite membrane include γ-AlOOH hierarchical porous microspheres prepared by the above method, and the organic matrix includes chitosan or sodium alginate.
[0024] When the organic matrix is chitosan, the preparation method of this organic-inorganic composite membrane includes:
[0025] Chitosan was dissolved in an aqueous acetic acid solution and stirred until dissolved. Glutaraldehyde was then added to crosslink the solution to obtain a pure chitosan casting solution.
[0026] γ-AlOOH hierarchical porous microspheres were added to pure chitosan casting solution, and the composite membrane casting solution was obtained after thorough stirring.
[0027] The composite membrane casting solution was poured into a petri dish, dried at room temperature, and then the membrane was peeled off to obtain the organic-inorganic composite membrane.
[0028] When the organic matrix is sodium alginate, the preparation method of this organic-inorganic composite membrane includes:
[0029] Sodium alginate was dissolved in water and stirred until dissolved. Calcium chloride was added to crosslink the solution to obtain pure sodium alginate casting solution.
[0030] γ-AlOOH hierarchical porous microspheres were added to pure sodium alginate casting solution, and the composite membrane casting solution was obtained after thorough stirring.
[0031] The composite membrane casting solution was poured into a petri dish, dried at room temperature, and then the membrane was peeled off to obtain the organic-inorganic composite membrane.
[0032] Thirdly, this application provides an application of the γ-AlOOH hierarchical porous microspheres prepared by the above method, which are used to prepare organic-inorganic composite membranes.
[0033] Fourthly, this application provides another application of the γ-AlOOH hierarchical porous microspheres or organic-inorganic composite membranes constructed therefrom prepared by the above method, using the γ-AlOOH hierarchical porous microspheres or organic-inorganic composite membranes for adsorbing dyes or adsorbing heavy metal ions.
[0034] Fifthly, this application provides Fe2O3 hierarchical porous microspheres prepared by the above method for adsorbing dyes.
[0035] Sixthly, this application provides a method for catalytically degrading tetracycline in pharmaceutical wastewater using TiO2-Ⅰ and TiO2-Ⅱ functional nano-oxides prepared by the above method.
[0036] The present invention has the following beneficial effects:
[0037] This invention provides a rotary hydrothermal method for extracting valuable metals from red mud to prepare functional oxides, as well as the construction and application of composite membranes. This method effectively extracts Al, Fe, and Ti, which are abundant in red mud, through acid leaching. Then, using a mild rotary hydrothermal method, the extracted Al, Fe, and Ti are prepared into γ-AlOOH hierarchical porous microspheres, Fe2O3 hierarchical porous microspheres, and TiO2-Ⅰ and TiO2-Ⅱ functional nano-oxides. These are then applied to wastewater treatment, solving the problem of dual pollution from red mud and industrial wastewater.
[0038] Compared to the traditional static hydrothermal method, the rotary hydrothermal method produces γ-AlOOH hierarchical porous microspheres, Fe2O3 hierarchical porous microspheres, TiO2-Ⅰ functional nano-oxides, and TiO2-Ⅱ functional nano-oxides with narrower particle size distribution, more uniform morphology, and larger specific surface area. This enhances their ability to adsorb organic dyes such as Congo red, adsorb hexavalent chromium, and catalyze the degradation of tetracycline. Furthermore, the mechanical properties, anti-swelling properties, and adsorption performance of organic-inorganic composite membranes prepared using γ-AlOOH hierarchical porous microspheres as inorganic additives are significantly improved. This preparation method is simple, effective, and environmentally friendly, achieving the goal of "treating waste with waste and turning waste into treasure." Attached Figure Description
[0039] Figure 1 The XRD (X-ray diffraction) spectrum of the γ-AlOOH hierarchical porous microspheres prepared in Example 1 of this application;
[0040] Figure 2 SEM (scanning electron microscope) image and particle size distribution diagram of the γ-AlOOH hierarchical porous microspheres prepared in Example 1 of this application;
[0041] Figure 3 The N2 adsorption-desorption curves and pore size distribution diagrams of the γ-AlOOH hierarchical porous microspheres prepared in Example 1 of this application are shown.
[0042] Figure 4 The XRD pattern of the Fe2O3 hierarchical porous microspheres prepared in Example 1 of this application;
[0043] Figure 5 The XRD spectra of TiO2-Ⅰ functional nano-oxide and TiO2-Ⅱ functional nano-oxide prepared in Example 1 of this application;
[0044] Figure 6 SEM image of the γ-AlOOH hierarchical porous microspheres prepared in Comparative Example 1 of this application;
[0045] Figure 7 N2 adsorption-desorption curves and pore size distribution of the γ-AlOOH hierarchical porous microspheres prepared in Comparative Example 1 of this application;
[0046] Figure 8 These are XRD comparison images of TiO2-II prepared in Example 1 and Comparative Example 1 of this application;
[0047] Figure 9 This is a comparison of the adsorption effects of γ-AlOOH hierarchical porous microspheres prepared in Example 1 and Comparative Example 1 of this application on Congo red.
[0048] Figure 10 This is a comparison diagram showing the adsorption effect of Fe2O3 hierarchical porous microspheres prepared in Example 1 and Comparative Example 1 on Congo red.
[0049] Figure 11 The diagram shows the catalytic degradation performance of tetracycline by the TiO2-Ⅰ and TiO2-Ⅱ functional nano-oxides prepared in Example 1 of this application.
[0050] Figure 12The image shows the adsorption performance of the γ-AlOOH hierarchical porous microspheres prepared in Example 1 of this application for hexavalent chromium in water.
[0051] Figure 13 Digital photographs and SEM images of organic-inorganic composite membranes;
[0052] Figure 14 The graph shows the test results of mechanical properties and anti-swelling properties of organic-inorganic composite membranes and pure chitosan membranes. Detailed Implementation
[0053] The technical solution of the present invention will be further explained and described below through specific embodiments.
[0054] This application provides a rotary hydrothermal method for extracting valuable metals from red mud to prepare functional oxides. The reaction principle of this method is as follows: sodium aluminate solution, Fe-containing solid, and Ti-containing solid are extracted from red mud separately. Specifically, by mixing red mud with acid and reacting, a supernatant containing Al and Fe, and a Ti-containing solid are obtained after separation. The Al- and Fe-containing supernatant is stirred with sodium hydroxide solution to obtain sodium aluminate solution and Fe-containing solid. After mixing the sodium aluminate solution with urea and treating it by rotary hydrothermal method, γ-AlOOH hierarchical porous microspheres with narrower particle size distribution, more uniform sphericity, and larger specific surface area are successfully prepared at a lower temperature and in a shorter time. After mixing the Fe-containing solid with acid and urea and treating it by rotary hydrothermal method, Fe2O3 hierarchical porous microspheres with relatively weak crystallinity but more surface active sites and superior performance are obtained.
[0055] In addition, Ti is extracted from the Ti-containing solid using a two-step method. First, the Ti-containing solid is immersed in sulfuric acid to obtain a titanium-rich solution and a solid A containing a small amount of Ti. Then, the titanium-rich solution is mixed with ammonia to precipitate TiO2-Ⅰ functional nano-oxides. Finally, the solid A containing a small amount of Ti is mixed with sodium hydroxide, and the solid obtained by filtration is subjected to rotary hydrothermal treatment with hydrofluoric acid to further recover Ti, yielding TiO2-Ⅱ functional nano-oxides.
[0056] The prepared γ-AlOOH hierarchical porous microspheres were successfully used to construct an organic-inorganic composite membrane with an organic matrix. Both this organic-inorganic composite membrane and the Fe2O3 hierarchical porous microspheres can be used for dye adsorption, and they exhibit excellent performance in the removal of organic dyes. The prepared TiO2-Ⅰ and TiO2-Ⅱ functional nano-oxides can be used for the catalytic degradation of antibiotics in pharmaceutical wastewater, and they show excellent performance.
[0057] The following describes, by way of specific embodiments, the rotary hydrothermal method for extracting valuable metals from red mud to prepare functional oxides, the construction of composite membranes and their applications.
[0058] Example 1
[0059] This application provides a rotary hydrothermal method for extracting valuable metals from red mud to prepare functional oxides, the method comprising:
[0060] S101: Red mud was mixed with 5.0 mol / L hydrochloric acid and heated to 100℃, then stirred continuously for 2.5 h to obtain a reaction mixture. The reaction mixture was separated by suction filtration through a Buchner funnel to obtain a supernatant and Ti-containing solids. The pH of the supernatant was adjusted to 11.0 with a 6.0 mol / L sodium hydroxide solution, and stirred for 2.0 h to obtain a mixture. This mixture was separated by suction filtration through a Buchner funnel to obtain a sodium aluminate solution and Fe-containing solids.
[0061] S102: Sodium aluminate solution and 1.0 mol / L urea were stirred evenly and then placed into a reactor. A rotary hydrothermal reaction was carried out at 130℃ and a rotation frequency of 5 Hz for 8.0 h. After the reaction was completed, the mixture was cooled to room temperature and separated by suction filtration through a Buchner funnel to obtain γ-AlOOH hierarchical porous microspheres.
[0062] S103: Fe solid was mixed with 1.5 mol / L nitric acid at a solid-liquid ratio of 1:30, and then 1.0 mol / L urea was added and mixed again. The mixture was then placed in a reactor and subjected to a rotary hydrothermal reaction at 120℃ and 5 Hz for 12.0 h. After the rotary hydrothermal reaction was completed, the mixture was cooled to room temperature and separated by suction filtration through a Buchner funnel to obtain Fe2O3 hierarchical porous microspheres.
[0063] S104: Ti-containing solid was mixed with 60% sulfuric acid at a solid-liquid ratio of 1:10 and stirred for 3.0 h. The mixture was then separated by filtration through a Buchner funnel to obtain a titanium-rich solution and solid A.
[0064] S105: Add 20% ammonia water to the titanium-rich solution and co-precipitate at room temperature for 3.0 h to obtain TiO2-Ⅰ functional nano-oxide.
[0065] S106: Solid A was mixed with a 3.0 mol / L sodium hydroxide solution at a solid-liquid ratio of 1:30 and stirred for 3.0 h. The mixture was then separated by suction filtration through a Buchner funnel to obtain solid B.
[0066] S107: Solid B and 25% hydrofluoric acid were mixed at a solid-liquid ratio of 1:15 and then placed in a reactor. The mixture was subjected to a rotary hydrothermal reaction at 30℃ and a rotation frequency of 5 Hz for 3.0 h. After the rotary hydrothermal reaction was completed, the mixture was cooled to room temperature and separated by suction filtration through a Buchner funnel to obtain TiO2-II functional nano-oxides.
[0067] Example 2
[0068] This application provides a rotary hydrothermal method for extracting valuable metals from red mud to prepare functional oxides, the method comprising:
[0069] S201: Red mud was mixed with 6.0 mol / L hydrochloric acid and heated to 100℃, then stirred continuously for 2.5 h to obtain a reaction mixture. The reaction mixture was separated by suction filtration through a Buchner funnel to obtain a supernatant and Ti-containing solids. The pH of the supernatant was adjusted to 11.5 with a 6.0 mol / L sodium hydroxide solution, and stirred for 2.0 h to obtain a mixture. This mixture was separated by suction filtration through a Buchner funnel to obtain a sodium aluminate solution and Fe-containing solids.
[0070] S202: Sodium aluminate solution and urea at a concentration of 1.0 mol / L were stirred evenly and then placed into a reactor. The reaction was carried out under hydrothermal conditions at 130℃ and a rotation frequency of 7 Hz for 8.0 h. After the reaction was completed, the mixture was cooled to room temperature and separated by suction filtration through a Buchner funnel to obtain γ-AlOOH hierarchical porous microspheres.
[0071] S2O3: Fe-containing solid was mixed with 2.0 mol / L nitric acid at a solid-liquid ratio of 1:30, and then 1.5 mol / L urea was added and mixed again. The mixture was then placed in a reactor and subjected to a rotary hydrothermal reaction at 130℃ and a rotation frequency of 7 Hz for 12.0 h. After the rotary hydrothermal reaction was completed, the mixture was cooled to room temperature and separated by suction filtration through a Buchner funnel to obtain Fe2O3 hierarchical porous microspheres.
[0072] S204: Ti-containing solid was mixed with 70% sulfuric acid at a solid-liquid ratio of 1:10 and stirred for 4.0 h. The mixture was then separated by suction filtration through a Buchner funnel to obtain a titanium-rich liquid and solid A.
[0073] S205: Add 22.5% ammonia water to the titanium-rich solution and co-precipitate at room temperature for 3.5 h to obtain TiO2-Ⅰ functional nano-oxide.
[0074] S206: Solid A is mixed with a 4.0 mol / L sodium hydroxide solution at a solid-liquid ratio of 1:30 and stirred for 4 hours. The mixture is then separated by suction filtration through a Buchner funnel to obtain solid B.
[0075] S207: Solid B and 30% hydrofluoric acid were mixed at a solid-liquid ratio of 1:15 and then placed in a reactor. The mixture was subjected to a rotary hydrothermal reaction at 40℃ and a rotation frequency of 7 Hz for 4.0 h. After the rotary hydrothermal reaction was completed, the mixture was cooled to room temperature and separated by suction filtration through a Buchner funnel to obtain TiO2-II functional nano-oxides.
[0076] Example 3
[0077] This application provides a rotary hydrothermal method for extracting valuable metals from red mud to prepare functional oxides, the method comprising:
[0078] S301: Red mud was mixed with 8.0 mol / L hydrochloric acid and heated to 100℃, then stirred continuously for 2.5 h to obtain a reaction mixture. The reaction mixture was separated by suction filtration through a Buchner funnel to obtain a supernatant and Ti-containing solids. The pH of the supernatant was adjusted to 11.8 with 8.0 mol / L sodium hydroxide solution, and stirred for 2.0 h to obtain a mixture. This mixture was separated by suction filtration through a Buchner funnel to obtain a sodium aluminate solution and Fe-containing solids.
[0079] S302: Sodium aluminate solution and urea at a concentration of 1.0 mol / L were stirred evenly and then placed into a reactor. The reaction was carried out under hydrothermal conditions at 130℃ and a rotation frequency of 10 Hz for 8.0 h. After the reaction was completed, the mixture was cooled to room temperature and separated by suction filtration through a Buchner funnel to obtain γ-AlOOH hierarchical porous microspheres.
[0080] S303: Fe-containing solids are mixed with 3.0 mol / L nitric acid, hydrochloric acid, or sulfuric acid at a solid-liquid ratio of 1:30, and then 2.0 mol / L urea is added and mixed again. The mixture is then placed in a reactor and subjected to a rotary hydrothermal reaction at 180℃ and 10 Hz for 12.0 h. After the rotary hydrothermal reaction is complete, the mixture is cooled to room temperature and separated by suction filtration through a Buchner funnel to obtain Fe2O3 hierarchical porous microspheres.
[0081] S304: Ti-containing solid was mixed with 90% sulfuric acid at a solid-liquid ratio of 1:10 and stirred for 5.0 h. The mixture was then separated by suction filtration through a Buchner funnel to obtain a titanium-rich liquid and solid A.
[0082] S305: Add 25% ammonia water to the titanium-rich solution and co-precipitate at room temperature for 4.0 h to obtain TiO2-Ⅰ functional nano-oxide.
[0083] S306: Solid A is mixed with a 5.0 mol / L sodium hydroxide solution at a solid-liquid ratio of 1:30 and stirred for 5.0 h. The mixture is then separated by suction filtration through a Buchner funnel to obtain solid B.
[0084] S307: Solid B and 35% hydrofluoric acid were mixed at a solid-liquid ratio of 1:15 and then placed in a reactor. The mixture was subjected to a rotary hydrothermal reaction at 50℃ and a rotation frequency of 10 Hz for 5.0 h. After the rotary hydrothermal reaction was completed, the mixture was cooled to room temperature and separated by suction filtration through a Buchner funnel to obtain TiO2-II functional nano-oxides.
[0085] Example 4
[0086] This application provides a rotary hydrothermal method for extracting valuable metals from red mud to prepare functional oxides, the method comprising:
[0087] S401: Red mud was mixed with 12.0 mol / L hydrochloric acid and heated to 80℃, then stirred continuously for 1.0 h to obtain a reaction mixture. The reaction mixture was separated by suction filtration through a Buchner funnel to obtain a supernatant and Ti-containing solids. The pH of the supernatant was adjusted to 12.2 with a 6.0 mol / L sodium hydroxide solution, and stirred for 2.0 h to obtain a mixture. This mixture was then separated by suction filtration through a Buchner funnel to obtain a sodium aluminate solution and Fe-containing solids.
[0088] S402: Sodium aluminate solution and urea were stirred evenly and then placed into a reactor. A hydrothermal reaction was carried out at 120℃ and 1 Hz for 7.0 h. After the reaction was completed, the mixture was cooled to room temperature and separated by suction filtration through a Buchner funnel to obtain γ-AlOOH hierarchical porous microspheres.
[0089] S403: Fe solid was mixed with 5.0 mol / L hydrochloric acid at a solid-liquid ratio of 1:30, and then 3.0 mol / L urea was added and mixed again. The mixture was then placed in a reactor and subjected to a rotary hydrothermal reaction at 110℃ and 1 Hz for 8.0 h. After the rotary hydrothermal reaction was completed, the mixture was cooled to room temperature and separated by suction filtration through a Buchner funnel to obtain Fe2O3 hierarchical porous microspheres.
[0090] S404: Ti-containing solid was mixed with 70% sulfuric acid at a solid-liquid ratio of 1:10 and stirred for 2.0 h. The mixture was then separated by suction filtration through a Buchner funnel to obtain a titanium-rich liquid and solid A.
[0091] S405: Add 21% ammonia water to the titanium-rich solution and co-precipitate at room temperature for 5.0 h to obtain TiO2-Ⅰ functional nano-oxide.
[0092] S406: Solid A is mixed with a 2.0 mol / L sodium hydroxide solution at a solid-liquid ratio of 1:30 and stirred for 2.0 h. The mixture is then separated by suction filtration through a Buchner funnel to obtain solid B.
[0093] S407: Solid B and 20% hydrofluoric acid were mixed at a solid-liquid ratio of 1:15 and then placed in a reactor. The mixture was subjected to a rotary hydrothermal reaction at 25°C and a rotation frequency of 1 Hz for 2.0 h. After the rotary hydrothermal reaction was completed, the mixture was cooled to room temperature and separated by suction filtration through a Buchner funnel to obtain TiO2-II functional nano-oxides.
[0094] Example 5
[0095] This application provides a rotary hydrothermal method for extracting valuable metals from red mud to prepare functional oxides, the method comprising:
[0096] S501: Red mud was mixed with 10.0 mol / L hydrochloric acid and heated to 90℃, then stirred continuously for 4.0 h to obtain a reaction mixture. The reaction mixture was separated by suction filtration through a Buchner funnel to obtain a supernatant and Ti-containing solids. The pH of the supernatant was adjusted to 12.0 with a 6.0 mol / L sodium hydroxide solution, and stirred for 2.0 h to obtain a mixture. This mixture was then separated by suction filtration through a Buchner funnel to obtain a sodium aluminate solution and Fe-containing solids.
[0097] S502: Sodium aluminate solution and urea were stirred evenly and then placed into a reactor. A hydrothermal reaction was carried out at 125℃ and 15 Hz for 9.0 h. After the reaction was completed, the mixture was cooled to room temperature and separated by suction filtration through a Buchner funnel to obtain γ-AlOOH hierarchical porous microspheres.
[0098] S503: Fe solid was mixed with 6.0 mol / L sulfuric acid at a solid-liquid ratio of 1:30, and then 3.0 mol / L urea was added and mixed again. The mixture was then placed in a reactor and subjected to a rotary hydrothermal reaction at 200℃ and 15 Hz for 6.0 h. After the rotary hydrothermal reaction was completed, the mixture was cooled to room temperature and separated by suction filtration through a Buchner funnel to obtain Fe2O3 hierarchical porous microspheres.
[0099] S504: Ti-containing solid was mixed with 70% sulfuric acid at a solid-liquid ratio of 1:10 and stirred for 6.0 h. The mixture was then separated by suction filtration through a Buchner funnel to obtain a titanium-rich liquid and solid A.
[0100] S505: Add 22% ammonia water to the titanium-rich solution and co-precipitate at room temperature for 5.0 h to obtain TiO2-Ⅰ functional nano-oxide.
[0101] S506: Solid A is mixed with a 7.0 mol / L sodium hydroxide solution at a solid-liquid ratio of 1:30 and stirred for 6.0 h. The mixture is then separated by suction filtration through a Buchner funnel to obtain solid B.
[0102] S507: Solid B and 40% hydrofluoric acid were mixed at a solid-liquid ratio of 1:15 and then placed in a reactor. The mixture was subjected to a rotary hydrothermal reaction at 60℃ and a rotation frequency of 15Hz for 4.0 h. After the rotary hydrothermal reaction was completed, the mixture was cooled to room temperature and separated by suction filtration through a Buchner funnel to obtain TiO2-II functional nano-oxides.
[0103] Comparative Example 1
[0104] Comparative Example 1 of this application provides a static hydrothermal method for extracting valuable metals from red mud to prepare functional oxides, the method comprising:
[0105] D101: Red mud was mixed with 5.0 mol / L hydrochloric acid and heated to 100℃, then stirred continuously for 2.5 h to obtain a reaction mixture. The reaction mixture was separated by suction filtration through a Buchner funnel to obtain a supernatant and Ti-containing solids. The pH of the supernatant was adjusted to 11.0 with a 6.0 mol / L sodium hydroxide solution, and stirred for 2.0 h to obtain a mixture. This mixture was then separated by suction filtration through a Buchner funnel to obtain a sodium aluminate solution and Fe-containing solids.
[0106] D102: Sodium aluminate solution and 1.0 mol / L urea were stirred evenly and then placed into a reactor. The reaction was carried out hydrothermally at 130℃ for 8.0 h. After the reaction was completed, the mixture was cooled to room temperature and separated by suction filtration through a Buchner funnel to obtain γ-AlOOH hierarchical porous microspheres.
[0107] D103: Fe-containing solid was mixed with 1.5 mol / L nitric acid at a solid-liquid ratio of 1:30, and then 1.0 mol / L urea was added and mixed again. The mixture was then placed in a reactor and subjected to hydrothermal reaction at 120℃ for 12.0 h. After the reaction was complete, the mixture was cooled to room temperature and separated by suction filtration through a Buchner funnel to obtain Fe2O3 hierarchical porous microspheres.
[0108] D104: Ti-containing solid was mixed with 60% sulfuric acid at a solid-liquid ratio of 1:10 and stirred for 3.0 h. The mixture was then separated by suction filtration through a Buchner funnel to obtain a titanium-rich solution and solid A.
[0109] D105: Add 20% ammonia water to the titanium-rich solution and co-precipitate at room temperature for 3.0 h to obtain TiO2-Ⅰ functional nano-oxide.
[0110] D106: Solid A was mixed with a 3.0 mol / L sodium hydroxide solution at a solid-liquid ratio of 1:30 and stirred for 3.0 h. The mixture was then separated by suction filtration through a Buchner funnel to obtain solid B.
[0111] D107: Solid B and 25% hydrofluoric acid were mixed at a solid-liquid ratio of 1:15 and then placed in a reactor. The mixture was subjected to hydrothermal reaction at 30℃ for 3.0 h. After the reaction was completed, the mixture was cooled to room temperature and separated by suction filtration through a Buchner funnel to obtain TiO2-II functional nano-oxides.
[0112] In this application, the functional oxides prepared in Example 1 and Comparative Example 1 were subjected to XRD, SEM, and N2 adsorption-desorption tests. The functional oxides prepared in Example 1 were also tested for their dye adsorption performance, metal ion adsorption performance, tetracycline catalytic degradation performance, and the mechanical properties of the organic-inorganic composite membrane. These tests are described in detail below.
[0113] 1. Detection of the functional oxides prepared in Example 1 and Comparative Example 1 by XRD, SEM, and N2 adsorption / desorption.
[0114] In this application, the γ-AlOOH hierarchical porous microspheres prepared in Example 1 were subjected to XRD, SEM, and N2 adsorption-desorption detection to obtain the adsorption and desorption results, respectively. Figure 1-3 XRD analysis was performed on Fe2O3 hierarchical porous microspheres to obtain the attached... Figure 4 XRD analysis was performed on TiO2-Ⅰ and TiO2-Ⅱ functional nano-oxides to obtain the attached... Figure 5 Meanwhile, SEM and N2 adsorption-desorption detection were performed on the γ-AlOOH hierarchical porous microspheres prepared in Comparative Example 1, and the adsorption and desorption results were obtained respectively. Figure 6 , 7 Furthermore, this application also compares the TiO2-II functional nano-oxides prepared in Example 1 and Comparative Example 1 using XRD, and obtains the results. Figure 8 .
[0115] From the appendix Figure 1 It can be seen that the XRD pattern of the γ-AlOOH hierarchical porous microspheres prepared in Example 1 matches well with the XRD standard card number JCPDS No. 21-1307, indicating that the product composition is relatively pure.
[0116] From the appendix Figure 2 As can be seen, the surface of the γ-AlOOH hierarchical porous microspheres prepared in Example 1 is a microsphere composed of two micro-nanosheets that are self-assembled, with a particle size of 1.0-2.3 μm and a uniform particle size distribution.
[0117] From the appendix Figure 3 As can be seen, the pore size of the γ-AlOOH hierarchical porous microspheres prepared in Example 1 is approximately 24.42 nm, and the specific surface area is 116.5 m². 2 / g, pore volume is 0.71 cm³ 3 Approximately / g.
[0118] From the appendix Figure 4 It can be seen that the XRD pattern of the Fe2O3 hierarchical porous microspheres prepared in Example 1 matches well with the XRD standard card number JCPDS No. 33-0664, indicating that the product composition is relatively pure.
[0119] From the appendix Figure 5 As can be seen, the XRD pattern of the TiO2-Ⅰ functional nano-oxide prepared in Example 1 matches well with XRD standard card number JCPDS No. 73-2224, indicating that the product composition is relatively pure. The XRD pattern of the TiO2-Ⅱ functional nano-oxide prepared in Example 1 matches both XRD standard card numbers JCPDS No. 73-2224 and JCPDS No. 73-1764, indicating that the TiO2-Ⅱ functional nano-oxide is composed of TiO2 with XRD standard card numbers JCPDS No. 73-2224 and JCPDS No. 73-1764.
[0120] From the appendix Figure 6 As can be seen, the surface of the γ-AlOOH hierarchical porous microspheres prepared in Comparative Example 1 consists of self-assembled micro / nanosheet microspheres with a particle size of 1.3-3.3 μm. Compared with the γ-AlOOH hierarchical porous microspheres prepared in Example 1, the γ-AlOOH hierarchical porous microspheres prepared in Comparative Example 1 have a wider particle size distribution and larger particle size. This indicates that the rotational hydrothermal reaction can reduce the particle size of the γ-AlOOH hierarchical porous microspheres, narrowing the particle size range and resulting in a more uniform morphology.
[0121] From the appendix Figure 7 As can be seen, the pore size of the γ-AlOOH hierarchical porous microspheres prepared in Comparative Example 1 is approximately 15.6 nm, and the specific surface area is 100.5 m². 2 / g, pore volume is 0.39 cm³ 3 Approximately / g. Compared with the γ-AlOOH hierarchical porous microspheres prepared in Example 1, the γ-AlOOH hierarchical porous microspheres prepared in Comparative Example 1 have smaller pore size, specific surface area, and pore volume. This indicates that the rotating hydrothermal reaction can increase the pore size, specific surface area, and pore volume of the γ-AlOOH hierarchical porous microspheres.
[0122] From the appendix Figure 8 As can be seen, the XRD pattern of the TiO2-II functional nano-oxide prepared in Comparative Example 1 shows a peak that does not belong to TiO2 at a diffraction angle of approximately 17°, indicating that the product is not pure. However, the XRD pattern of the TiO2-II functional nano-oxide prepared in Example 1 does not show this peak at a diffraction angle of approximately 17°, which means that rotary hydrothermal synthesis is beneficial to the product synthesis and avoids the generation of impurity phases.
[0123] 2. Testing the dye adsorption performance of the γ-AlOOH hierarchical porous microspheres prepared in Example 1 and Comparative Example 1.
[0124] A Congo red solution with a concentration of 300.0 mg / L was prepared in advance. 20.0 mg of the γ-AlOOH hierarchical porous microspheres prepared in Example 1 and Comparative Example 1 were added to the prepared Congo red solution for adsorption. Samples were taken every 120 min, and the concentration of Congo red in the solution was measured using a UV spectrophotometer to monitor the adsorption capacity of the γ-AlOOH hierarchical porous microspheres for Congo red within 120 min. The results are shown in the attached figure. Figure 9 As shown.
[0125] From the appendix Figure 9 As shown, within the same time frame, the γ-AlOOH hierarchical porous microspheres prepared in Example 1 adsorbed more Congo red solution and at a faster adsorption rate than those prepared in Comparative Example 1. This indicates that the γ-AlOOH hierarchical porous microspheres prepared by the rotary hydrothermal method can adsorb more dyes more quickly.
[0126] 3. Testing the dye adsorption performance of the Fe2O3 hierarchical porous microspheres prepared in Example 1 and Comparative Example 1.
[0127] A 50.0 mg / L Congo red solution was prepared in advance. 20.0 mg of the Fe₂O₃ hierarchical porous microspheres prepared in Example 1 and Comparative Example 1 were added to the prepared Congo red solution for adsorption. Samples were taken every 10 min, and the concentration of Congo red in the solution was measured using a UV spectrophotometer to monitor the adsorption capacity of the Fe₂O₃ hierarchical porous microspheres for Congo red solution over 60 min. The results are shown in the attached figure. Figure 10 As shown.
[0128] From the appendix Figure 10 As shown, within the same time frame, the Fe2O3 hierarchical porous microspheres prepared in Example 1 adsorbed more Congo red solution and at a faster adsorption rate than those prepared in Comparative Example 1. This indicates that the Fe2O3 hierarchical porous microspheres prepared by the rotary hydrothermal method can adsorb more dyes more quickly.
[0129] 4. Test the catalytic degradation performance of tetracycline by the TiO2-Ⅰ functional nano-oxides and TiO2-Ⅱ functional nano-oxides prepared in Example 1 and the TiO2-Ⅱ functional nano-oxide prepared in Comparative Example 1.
[0130] A tetracycline solution with a concentration of 50.0 mg / L was prepared in advance. 20.0 mg of each of the TiO2-I and TiO2-II functional nano-oxides prepared in Example 1 and Comparative Example 1 were added to the tetracycline solution, respectively. Samples were taken every 20 min, and the concentration of tetracycline in the solution was measured using a UV spectrophotometer to monitor the catalytic activity of the TiO2-I and TiO2-II functional nano-oxides on the tetracycline solution within 240 min. The results are shown in the attached figure. Figure 11 As shown.
[0131] From the appendix Figure 11 It is evident that TiO2-II functional nano-oxides exhibit better catalytic performance compared to TiO2-I functional nano-oxides. Furthermore, the TiO2-II functional nano-oxides prepared in Example 1 demonstrate even better catalytic performance than those prepared in Comparative Example 1. This indicates that the TiO2-II functional nano-oxides prepared via the rotary hydrothermal method exhibit the optimal catalytic performance for tetracycline.
[0132] 5. Testing the adsorption performance of γ-AlOOH hierarchical porous microspheres prepared in Example 1 on hexavalent chromium in water.
[0133] A hexavalent chromium solution with a concentration of 100.0 mg / L was prepared using potassium dichromate. 20.0 mg of the γ-AlOOH hierarchical porous microspheres prepared in Example 1 were added to the prepared hexavalent chromium solution for adsorption. The concentration of the hexavalent chromium solution was measured every 5 min using diphenylcarbazide spectrophotometry to monitor the adsorption capacity of the γ-AlOOH hierarchical porous microspheres over 120 min. The results are shown in the attached figure. Figure 12 As shown.
[0134] From the appendix Figure 12 It is evident that the γ-AlOOH hierarchical porous microspheres can reach equilibrium in adsorbing hexavalent chromium within a relatively short time, with an adsorption capacity of approximately 28.0 mg / g. This indicates that the γ-AlOOH hierarchical porous microspheres can treat various pollutants in wastewater, such as chromium-containing pollutants.
[0135] 6. The adsorption isotherm properties of the γ-AlOOH hierarchical porous microspheres prepared in Example 1 for Congo red dye and methylene blue dye were tested.
[0136] The γ-AlOOH hierarchical porous microspheres prepared in Example 1 were subjected to adsorption isotherm experiments on Congo red dye and methylene blue dye, respectively. According to the Langmuir model fitting, the maximum adsorption capacity of the γ-AlOOH hierarchical porous microspheres for Congo red dye was 602.4 mg / g and the maximum adsorption capacity for methylene blue dye was 1208.7 mg / g, which were significantly higher than the adsorption capacity of other reported Al-based adsorbents.
[0137] 7. Detection of the mechanical properties, anti-swelling properties, and adsorption properties of the organic-inorganic composite membrane constructed from γ-AlOOH hierarchical porous microspheres.
[0138] The method for preparing the organic-inorganic composite membrane in this application includes:
[0139] 1) Dissolve chitosan in an aqueous acetic acid solution and stir until dissolved. Add glutaraldehyde to crosslink and obtain pure chitosan casting solution. Dry part of the pure chitosan casting solution at room temperature. After drying, peel off the film to obtain pure chitosan film.
[0140] 2) The γ-AlOOH hierarchical porous microspheres prepared in Example 1 were added to another part of the pure chitosan casting solution, and after thorough stirring, a composite membrane casting solution was obtained.
[0141] 3) Pour the composite membrane casting solution into a petri dish and dry it at room temperature. After drying, peel off the membrane to obtain the organic-inorganic composite membrane.
[0142] The prepared organic-inorganic composite membrane was digitally photographed and analyzed by SEM to obtain the attached... Figure 13 From the appendix Figure 13 As can be seen, the surface of the organic-inorganic composite membrane is smooth, but becomes rough when magnified to 100 μm.
[0143] The mechanical properties and anti-swelling properties of the prepared organic-inorganic composite membrane and pure chitosan membrane were tested, and the test results are attached. Figure 14 As shown in the attached document. Figure 14 As shown, compared to pure chitosan membranes, organic-inorganic composite membranes can enhance the mechanical properties and anti-swelling properties of the membrane.
[0144] Adsorption isotherms were performed on the prepared organic-inorganic composite membrane to adsorb Congo red dye. Langmuir model fitting revealed that the maximum adsorption capacity of the organic-inorganic composite membrane for Congo red dye was 969.4 mg / g, significantly higher than that of the γ-AlOOH hierarchical porous microspheres. This indicates that the organic-inorganic composite membrane constructed from γ-AlOOH hierarchical porous microspheres further enhances the adsorption capacity for Congo red.
[0145] In summary, among the γ-AlOOH hierarchical porous microspheres, Fe2O3 hierarchical porous microspheres, and TiO2-Ⅰ and TiO2-Ⅱ functional nano-oxides prepared by the rotary hydrothermal method, the γ-AlOOH hierarchical porous microspheres exhibit smaller particle size, narrower particle size distribution, more uniform morphology, and larger specific surface area. The γ-AlOOH and Fe2O3 hierarchical porous microspheres demonstrate better adsorption of Congo red. Furthermore, the γ-AlOOH hierarchical porous microspheres can adsorb hexavalent chromium in a shorter time. The TiO2-Ⅰ and TiO2-Ⅱ functional nano-oxides show better catalytic degradation of tetracycline. All of this indicates that functional oxides such as the γ-AlOOH hierarchical porous microspheres prepared by the rotary hydrothermal method can improve wastewater treatment capabilities.
[0146] The rotary hydrothermal method for extracting valuable metals from red mud and preparing functional oxides provided in this application effectively extracts Al, Fe, and Ti, which are present in high concentrations in the red mud, through acid leaching. Then, the extracted Al, Fe, and Ti are prepared into γ-AlOOH hierarchical porous microspheres, Fe2O3 hierarchical porous microspheres, and TiO2-Ⅰ and TiO2-Ⅱ functional nano-oxides using a mild rotary hydrothermal method. These are then applied to wastewater treatment, solving the problem of dual pollution from red mud and industrial wastewater. Furthermore, the rotary hydrothermal method improves the particle size, morphology, and specific surface area of the γ-AlOOH hierarchical porous microspheres, Fe2O3 hierarchical porous microspheres, and TiO2-Ⅰ and TiO2-Ⅱ functional nano-oxides, significantly enhancing their ability to adsorb organic dyes such as Congo red, catalytically degrade tetracycline, and adsorb hexavalent chromium. The mechanical properties, anti-swelling properties, and adsorption properties of the organic-inorganic composite membrane constructed using γ-AlOOH hierarchical porous microspheres as an inorganic additive are also further improved. This preparation method is simple, effective, green and environmentally friendly, realizing "using waste to treat waste and turning waste into treasure".
[0147] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.
Claims
1. A rotary hydrothermal method for extracting valuable metals from red mud to prepare functional oxides, characterized in that, include: S01: Extract sodium aluminate solution, Fe-containing solid and Ti-containing solid from red mud respectively; S02: The sodium aluminate solution and urea are mixed evenly and then subjected to a rotary hydrothermal reaction. After cooling to room temperature, the mixture is filtered to obtain γ-AlOOH hierarchical porous microspheres. S03: The Fe-containing solid was mixed with acid and then urea was added. After stirring evenly, a rotary hydrothermal reaction was carried out. After cooling to room temperature, the mixture was filtered to obtain Fe2O3 hierarchical porous microspheres. S04: The Ti-containing solid is immersed in sulfuric acid, stirred, and filtered to obtain a titanium-rich solution and solid A; S05: After the titanium-rich liquid is mixed with ammonia water, TiO2-I functional nano-oxide is obtained by co-precipitation at room temperature; S06: After mixing solid A with sodium hydroxide solution, stirring and filtering are performed to obtain solid B; S07: The solid B is mixed with hydrofluoric acid and subjected to a rotary hydrothermal reaction. After cooling to room temperature, it is filtered to obtain TiO2-II functional nano-oxide. The rotating hydrothermal reaction involves the material rotating in a reactor and undergoing a hydrothermal reaction. The reactor is a homogeneous reactor with axial overall rotation, a reactor equipped with radial mechanical stirring, or a dynamic stirred reactor using axial compressed air stirring. The rotation frequency of the reactor is 1-15 Hz.
2. The rotating hydrothermal method for extracting valuable metals from red mud and preparing functional oxides according to claim 1, characterized in that, In S03, the Fe-containing solid is mixed with nitric acid, hydrochloric acid or sulfuric acid with a concentration of 1.0-6.0 mol / L at a solid-liquid ratio of 1:30; the concentration of urea is 1.0-3.0 mol / L; the rotating hydrothermal reaction temperature is 110-200℃ and the reaction time is 6.0-12.0 h.
3. The rotating hydrothermal method for extracting valuable metals from red mud and preparing functional oxides according to claim 1, characterized in that, In S04, the Ti-containing solid is mixed with sulfuric acid of 60-90% concentration at a solid-liquid ratio of 1:10 and stirred for 2.0-6.0 hours; in S05, the concentration of ammonia water is 20-25%, and the amount added is until a suspension appears.
4. The rotary hydrothermal method for extracting valuable metals from red mud and preparing functional oxides according to claim 1, characterized in that, In S06, solid A is mixed with a sodium hydroxide solution with a concentration of 2.0-7.0 mol / L at a solid-liquid ratio of 1:30 and stirred for 2.0-6.0 h.
5. The rotary hydrothermal method for extracting valuable metals from red mud and preparing functional oxides according to claim 1, characterized in that, In S07, solid B is mixed with hydrofluoric acid at a concentration of 20-40% at a solid-liquid ratio of 1:15; the rotary hydrothermal reaction temperature is 25-60℃ and the reaction time is 2.0-4.0 h.
6. The rotating hydrothermal method for extracting valuable metals from red mud and preparing functional oxides according to claim 1, characterized in that, The γ-AlOOH hierarchical porous microspheres have a particle size of 1.0-2.3 μm and a specific surface area of 110-130 m². 2 / g.
7. An organic-inorganic composite membrane, characterized in that, The inorganic additives used in the construction of the composite membrane include γ-AlOOH hierarchical porous microspheres prepared by any one of the methods in claims 1-6, and the organic matrix includes chitosan or sodium alginate.
8. The γ-AlOOH hierarchical porous microspheres prepared by any one of the methods in claims 1-6 and the organic-inorganic composite membranes constructed therefrom are used for adsorbing dyes or heavy metal ions.
9. The Fe2O3 hierarchical porous microspheres prepared by any one of the methods in claims 1-6 are used for adsorbing dyes, and the TiO2-Ⅰ and TiO2-Ⅱ functional nano-oxides are used for catalytic degradation of tetracycline in pharmaceutical wastewater.