A method for preparing a porous zeolite composite material from iron tailings and uses thereof

Abstract

The application discloses a method for preparing porous zeolite composite materials from iron tailings and application, and converts fine-grained iron tailings with complex composition and low reaction activity into soluble salt through alkali fusion activation, and then converts the soluble salt into zeolite composite materials with uniform particle size and rich pores through hydrothermal crystallization. The application does not perform raw material pretreatment steps such as grinding and impurity removal, does not introduce a structure directing agent, controls the crystal structure of the iron tailings through alkali fusion activation-hydrothermal crystallization reaction, makes [SiO4] and [AlO6] structure units dissolve and recombine, simultaneously realizes in-situ doping and surface loading of iron elements, and constructs micrometer-level octahedral porous zeolite composite materials. The prepared porous zeolite composite materials have a large specific surface area, uniform pore size distribution and complete crystal structure, and exhibit excellent catalytic oxidation performance in a Fenton-like system, can efficiently remove emerging pollutants such as antibiotics, and are helpful to efficient and high-value utilization of fine-grained iron tailings resources, and have a wide application prospect in the field of wastewater treatment.

Description

Technical Field

[0001] This invention relates to the field of preparing environmentally functional materials from industrial solid waste and their high-value utilization technology, specifically to a method and application for preparing porous zeolite composite materials from iron tailings. Background Technology

[0002] Iron tailings are solid waste generated during the crushing, grinding, and beneficiation of iron ore to obtain iron concentrate. Due to the low grade of iron ore in my country, the beneficiation process requires two or even three stages of grinding, resulting in fine iron tailings particles. Fine iron tailings with a particle size of less than 0.075 mm account for more than 30% of the total tailings, posing a serious threat to regional air quality, water quality, and environmental safety. Currently, coarser iron tailings are widely used in the building materials industry as aggregates, cement clinker, and cementitious materials. However, the efficient utilization of fine iron tailings with a particle size of less than 0.075 mm has become an urgent environmental and resource issue. Generally, iron tailings powder contains a small amount of iron minerals and abundant silica and aluminum components. The mineral composition is mainly silicate minerals such as quartz, feldspar, and mica, exhibiting characteristics such as low monomer liberation, stable mineral structure, and low chemical activity. By regulating the basic structural units of iron tailings minerals and reconstructing the mineral phases, fine-grained iron tailings can be transformed into high-value-added mineral functional materials such as mesoporous silicates, mesoporous silica, and zeolite molecular sieves, which can be used to solve ecological and environmental problems and mineral resource shortages.

[0003] Zeolites are crystalline, three-dimensional porous aluminosilicates. The [SiO4] and [AlO4] tetrahedral units are connected by oxygen atoms, constructing a porous cage-like structure. This allows the zeolite framework to accommodate water molecules, potassium, sodium, and calcium ions, as well as small organic molecules, thus exhibiting excellent adsorption, catalytic, and ion exchange properties. Currently, many studies utilize industrial solid wastes such as coal gangue, fly ash, and red mud as inexpensive raw materials to synthesize zeolite materials. However, research on preparing zeolite materials from iron tailings is relatively limited. This is because iron tailings have uneven chemical composition, stable mineral phase structure, and low reactivity, leading to challenges such as high process costs and poor product controllability in zeolite synthesis. For example, CN117105241A discloses an ionic rare earth tailings-based zeolite material and a method for removing lead ions from solution. Thermally activated tailings are reacted with NaOH solution in an oil bath to generate cubic type A zeolite, which exhibits excellent Pb removal properties under strong acid conditions. 2+It exhibits good adsorption performance, with an adsorption capacity of up to 53.91 mg / g, demonstrating the practical application potential of zeolite materials synthesized from tailings in the removal of pollutants from water bodies. However, there are currently no reports on the in-situ conversion of multiple components such as Si, Al, and Fe from iron tailings into metal-supported porous zeolite composite materials. These materials, combined with the pore structure and surface adsorption characteristics of zeolite, and the synergistic effect of in-situ supported transition metal Fe, have not been reported to achieve pollutant enrichment and advanced oxidative degradation, thus hindering their application in the removal of organic pollutants from wastewater.

[0004] Therefore, this invention addresses the problems and shortcomings of existing methods for preparing zeolite materials from iron tailings. Based on the chemical composition and mineral structure characteristics of fine-grained iron tailings, it proposes a method to prepare a porous zeolite composite material with uniform particle size, abundant pores, high specific surface area, and excellent catalytic oxidation performance from fine-grained iron tailings with complex composition and low reactivity through a simple alkali fusion-hydrothermal process. This composite material can catalytically degrade emerging pollutants such as antibiotics, promote the efficient and high-value utilization of solid waste resources, and facilitate the solution of wastewater purification problems. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the first objective of this invention is to provide a method and application for preparing porous zeolite composite materials from iron tailings. This invention employs an alkali-fusion-hydrothermal method to restructure the mineral structure of fine-grained iron tailings, synthesizing micron-sized octahedral porous zeolite composite materials. Simultaneously, it achieves in-situ doping and surface loading of Fe, enabling excellent catalytic oxidation performance in Fenton-like systems. This allows for the efficient removal of emerging pollutants such as antibiotics, realizing the resource utilization and high-value utilization of all components of iron tailings. The second objective is to provide a method for preparing FAU-type porous zeolite composite materials from iron tailings.

[0006] To achieve the above-mentioned technical objectives, the technical solution of the present invention is as follows:

[0007] In a first aspect, the present invention provides a method for preparing porous zeolite composite material from iron tailings, wherein fine iron tailings and Al2O3 powder are activated by alkali fusion to obtain alkali-activated raw material; the alkali-activated raw material is then mixed with water at a liquid-solid ratio of 5:1-9:1 and subjected to hydrothermal crystallization reaction at 90-120 °C to obtain porous zeolite composite material.

[0008] The fine-grained iron tailings have a particle size of no more than 0.075 mm, a SiO2 mass content of no less than 60%, and a Fe2O3 mass content of no less than 6%; the molar ratio of SiO2 to Al2O3 is adjusted to 2.0-5.5 by adding Al2O3 powder.

[0009] Preferably, the molar ratio of SiO2 to Al2O3 is adjusted to 2.7-4.7 by adding Al2O3 powder; the mass content of Fe2O3 in the fine iron tailings is 8-10%; and the mass content of SiO2 is 65-75%.

[0010] Preferably, during alkali fusion activation, inorganic alkali powder is added, wherein the inorganic alkali is at least one of NaOH, KOH, Na2CO3, K2CO3, etc., and the mass ratio of the inorganic alkali powder to the total of fine iron tailings and Al2O3 powder is 0.8-1.2.

[0011] Preferably, the calcination temperature for alkali fusion activation is 550-850 ℃, and the calcination time is 2-4 h.

[0012] Secondly, the present invention protects the porous zeolite composite material obtained by the method, wherein the porous zeolite composite material is composed of zeolite and amorphous material, and the mass content of FAU type zeolite phase is greater than 10%.

[0013] Preferably, during the synthesis of the porous zeolite composite material, some Fe replaces Al in the zeolite and enters the framework structure, while some Fe is dissolved in the amorphous aluminosilicate phase, giving it high reactivity and exhibiting excellent catalytic oxidation performance against antibiotic pollutants in a Fenton-like system.

[0014] Thirdly, the present invention provides a method for preparing FAU-type porous zeolite composite material from iron tailings, wherein fine-grained iron tailings and Al2O3 powder are mixed to obtain a mixture, wherein the particle size of the fine-grained iron tailings is not greater than 0.075 mm, the mass content of SiO2 is not less than 60%, and the mass content of Fe2O3 is not less than 6%; the molar ratio of SiO2 to Al2O3 is adjusted to 3.7 by adding Al2O3 powder;

[0015] The mixture was heated to 550 °C in a muffle furnace at a heating rate of 5 °C / min for 3 h, and then cooled to obtain the alkali-activated raw material.

[0016] The alkali-activated raw material and water were then mixed evenly at a liquid-solid ratio of 5:1, and hydrothermally crystallized at 100 °C for 14 h to obtain FAU-type porous zeolite composite material.

[0017] Preferably, the FAU-type porous zeolite composite material comprises structurally complete and regularly morphologically regular FAU-type octahedral zeolite and surface-loaded amorphous aluminosilicate, exhibiting a composite pore structure with abundant micropores and partially mesopores, an average pore size of 1.94 nm, and a total pore volume of 0.259 cm³. 3 / g, with a specific surface area of ​​534.06 m². 2 / g.

[0018] Fourthly, the present invention provides an application of the material prepared by the above method, wherein the porous zeolite composite material is used for the catalytic degradation of organic pollutants in wastewater.

[0019] For the degradation of tetracycline hydrochloride, a tetracycline hydrochloride solution with an initial concentration of no more than 400 mg / L was prepared in an Erlenmeyer flask. The initial pH of the solution was adjusted to 2-3. 0.2-1.0 g / L of porous zeolite composite material was added to the tetracycline hydrochloride solution. After adding 10 mM H2O2 solution, the mixture was placed in a shaking incubator for reaction. A degradation rate of more than 90% was achieved within 20-120 min.

[0020] More preferably, the initial concentration of the tetracycline hydrochloride solution is 10-200 mg / L; the initial pH of the solution is adjusted to 2; and the amount of porous zeolite composite material added is 0.4 g / L.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] (1) In this invention, alkali fusion activation-hydrothermal crystallization is used to synthesize FAU-type porous zeolite composite material from iron tailings. During the alkali fusion activation process, inert mineral components such as quartz are converted into soluble silicates and aluminates, and the dissolution of metal elements in the tailings is promoted. During the subsequent hydrothermal crystallization process, structural units such as Si and Al are reorganized into porous zeolite composite material with micron-sized octahedral morphology.

[0023] (2) This invention uses fine-grained iron tailings that have not been impurity removed as raw material, retaining iron as the main impurity element, and realizes the efficient utilization of multiple components such as Si, Al and Fe. During the structural reconstruction process, some highly active Fe ions replace some of the Al in the zeolite framework to achieve in-situ doping, while the other part of Fe is dissolved in amorphous aluminosilicate nanoparticles and deposited on the surface of the zeolite material.

[0024] (3) The porous zeolite composite material prepared by this invention has the characteristics of high specific surface area, uniform particle size and controllable structural composition. The in-situ doping and surface loading of Fe element give it excellent catalytic oxidation performance. As a Fenton catalyst, it shows excellent potential in wastewater treatment and provides ideas for the full utilization of iron tailings. Through experimental testing, in the Fenton-like system, the porous zeolite composite material prepared from iron tailings has a significant effect on the removal of antibiotic pollutants and is significantly better than natural zeolite and pure silicon-aluminum source synthetic zeolite.

[0025] This application uses components from tailings waste to participate in the entire crystallization process, without the need for additional metal reagents. It is a zeolite composite material synthesized directly from iron tailings without impurity removal. The material has zeolite characteristics and exhibits excellent catalytic oxidation performance due to in-situ Fe loading. Attached Figure Description

[0026] Figure 1 The XRD patterns are of the porous zeolite composite materials prepared in Examples 1-8 and the materials prepared in Comparative Examples 1 and 2.

[0027] Figure 2 SEM image of the porous zeolite composite material prepared in Example 6;

[0028] Figure 3 The N2 adsorption-desorption curves and pore size distribution diagrams of the porous zeolite composite material prepared in Example 6 are shown.

[0029] Figure 4 XPS image of the porous zeolite composite material prepared in Example 6;

[0030] Figure 5 The graph shows a comparison of the adsorption and catalytic degradation of tetracycline hydrochloride by the materials prepared in Example 6 and Comparative Examples 1 and 2.

[0031] Figure 6 The catalytic degradation curves of the porous zeolite composite material prepared in Example 6 for tetracycline hydrochloride with different initial concentrations are shown. Detailed Implementation

[0032] To more clearly describe the purpose, technical solution, and advantages of this invention, the following examples are used to further illustrate the invention, rather than limiting the scope of protection of this invention.

[0033] The present invention provides a method for preparing porous zeolite composite materials from iron tailings, comprising the following steps:

[0034] (1) Alkali fusion activation: Fine iron tailings and Al2O3 powder are activated by alkali fusion to obtain alkali activated raw materials; Al2O3 powder is used to adjust the silicon-aluminum ratio. Inorganic alkali powder needs to be added during alkali fusion activation. Alkali fusion activation enables fine iron tailings and Al2O3 powder to be completely alkali fused at high temperature.

[0035] The fine-grained iron tailings have a particle size of no more than 0.075 mm, a SiO2 content of no less than 60%, and a Fe2O3 content of no less than 6%. The molar ratio of SiO2 to Al2O3 in the mixture of fine-grained iron tailings and Al2O3 powder is 2.0-5.5, preferably 2.7-4.7. When the molar ratio of SiO2 to Al2O3 is too small, such as 1.0, the composite material is prone to forming impurities and has poor stability. When the molar ratio of SiO2 to Al2O3 is too large, it is prone to crystallization problems.

[0036] (2) Hydrothermal crystallization: Add water to the alkali-activated raw material and stir. The liquid-solid ratio is 5:1-9:1 to obtain a precursor suspension. Pour the suspension into a polytetrafluoroethylene-lined reactor for hydrothermal crystallization reaction. The hydrothermal crystallization temperature is 90-120 ℃. The crystallized product is filtered, washed and dried to obtain a porous zeolite composite material.

[0037] As a preferred embodiment, the inorganic alkali used in step (1) is at least one of NaOH, KOH, etc., and the mass ratio of inorganic alkali powder to mixed powder (the sum of fine iron tailings and Al2O3 powder) is 0.8-1.2.

[0038] As a preferred option, the calcination temperature in step (1) is 550-850 ℃ and the holding time is 2-4 h.

[0039] As a preferred option, the hydrothermal crystallization temperature in step (2) is 90-110 ℃ and the time is 14 h.

[0040] In this invention, tetracycline hydrochloride was selected as a representative pollutant to test the catalytic oxidation performance of the material. The specific steps were as follows: 50 mL of tetracycline hydrochloride solution with an initial concentration of 200 mg / L was prepared in an Erlenmeyer flask, and the initial pH of the solution was adjusted to 2. 0.4 g / L of porous zeolite composite material was added to the tetracycline hydrochloride solution, followed by the addition of 10 mM H₂O₂ solution. The mixture was then placed in a shaking incubator for reaction. After 3 h of reaction, 3 mL of the supernatant was filtered through a 0.45 μm filter membrane. The absorbance of the filtrate was measured at a wavelength of 355 nm using a UV-Vis spectrophotometer. The degradation efficiency of the tetracycline hydrochloride pollutant was calculated based on the measured absorbance value and the standard curve.

[0041] In the following embodiments of the present invention, the selected fine-grained iron tailings raw material was ground (passed through a 200-mesh sieve) and dried. The chemical composition of the iron tailings was measured by X-ray fluorescence spectrometry (XRF) as shown in Table 1.

[0042]

[0043] Example 1

[0044] Al₂O₃ powder was added and mixed with iron tailings powder. The molar ratio of SiO₂ to Al₂O₃ was adjusted to 3.7. Then, NaOH solid particles were added, and the alkali-to-solid ratio (mass ratio of inorganic alkali powder to the total mass of fine iron tailings and Al₂O₃ powder) was adjusted to 1.0 before mixing. The mixture was then poured into a crucible and calcined in a muffle furnace at 5 ℃ / min to 550 ℃ for 3 h. After cooling, the alkali-activated raw material was obtained. The alkali-activated raw material was added to water at a liquid-to-solid ratio of 7:1 and stirred for 3 h to obtain a precursor suspension. This suspension was then poured into a polytetrafluoroethylene-lined reactor and hydrothermally crystallized at 100 ℃ for 14 h. The crystallized product was filtered, washed, and dried to obtain a porous zeolite composite material.

[0045] Through append Figure 1The XRD pattern shown indicates that the porous zeolite composite material prepared in this embodiment is mainly composed of FAU-type zeolite, with a certain amount of A-type zeolite, and other impurities with complex peak shapes. Using Jade 6.0 software and the peak fitting method, the FAU-type zeolite phase content in the zeolite composite material is calculated to be approximately 52.77%, with a specific surface area of ​​200.93 m². 2 / g, the tetracycline hydrochloride removal performance test results showed that the material removed 97.51% of tetracycline hydrochloride from aqueous solution.

[0046] Example 2

[0047] Al₂O₃ powder was added and mixed with iron tailings powder, adjusting the molar ratio of SiO₂ to Al₂O₃ to 3.7. Then, NaOH solid particles were added, and the alkali-to-solid ratio was adjusted to 1.0 before mixing. The mixture was then poured into a crucible and calcined in a muffle furnace at 5 ℃ / min to 550 ℃ for 3 h. After cooling, the alkali-activated raw material was obtained. The alkali-activated raw material was added to water at a liquid-to-solid ratio of 7:1 and stirred for 3 h to obtain a precursor suspension. This suspension was then poured into a polytetrafluoroethylene-lined reactor and hydrothermally crystallized at 90 ℃ for 14 h. The crystallized product was filtered, washed, and dried to obtain a porous zeolite composite material.

[0048] Through append Figure 1 The XRD pattern shown indicates that the porous zeolite composite material prepared in this embodiment is mainly composed of quartz and amorphous phases, with a low zeolite content. Using Jade 6.0 software and the peak fitting method, the content of FAU-type zeolite phase in the zeolite composite material is calculated to be approximately 27.73%, and the specific surface area is 36.25 m². 2 / g, the tetracycline hydrochloride removal performance test results showed that the material removed 96.64% of tetracycline hydrochloride from the aqueous solution.

[0049] Example 3

[0050] Al₂O₃ powder was added and mixed with iron tailings powder, adjusting the molar ratio of SiO₂ to Al₂O₃ to 3.7. Then, NaOH solid particles were added, and the alkali-to-solid ratio was adjusted to 1.0 before mixing. The mixture was then poured into a crucible and calcined in a muffle furnace at 5 ℃ / min to 550 ℃ for 3 h. After cooling, the alkali-activated raw material was obtained. The alkali-activated raw material was added to water at a liquid-to-solid ratio of 7:1 and stirred for 3 h to obtain a precursor suspension. This suspension was then poured into a polytetrafluoroethylene-lined reactor and hydrothermally crystallized at 110 ℃ for 14 h. The crystallized product was filtered, washed, and dried to obtain a porous zeolite composite material.

[0051] Through append Figure 1The XRD pattern shown indicates that the porous zeolite composite material prepared in this embodiment is mainly composed of FAU-type zeolite, with a certain amount of A-type and P-type zeolite also present. Using Jade 6.0 software and the peak fitting method, the content of the FAU-type zeolite phase in the zeolite composite material is approximately 52.37%, and the specific surface area is 200.09 m². 2 / g, the tetracycline hydrochloride removal performance test results showed that the material removed 97.66% of tetracycline hydrochloride from the aqueous solution.

[0052] Example 4

[0053] Al₂O₃ powder was added and mixed with iron tailings powder, adjusting the molar ratio of SiO₂ to Al₂O₃ to 2.7. Then, NaOH solid particles were added, and the alkali-to-solid ratio was adjusted to 1.0 before mixing. The mixture was then poured into a crucible and calcined in a muffle furnace at 5 ℃ / min to 550 ℃ for 3 h. After cooling, the alkali-activated raw material was obtained. The alkali-activated raw material was added to water at a liquid-to-solid ratio of 7:1 and stirred for 3 h to obtain a precursor suspension. This suspension was then poured into a polytetrafluoroethylene-lined reactor and hydrothermally crystallized at 100 ℃ for 14 h. The crystallized product was filtered, washed, and dried to obtain a porous zeolite composite material.

[0054] Through append Figure 1 The XRD pattern shown indicates that the porous zeolite composite material prepared in this embodiment is mainly composed of type A zeolite, with a low content of FAU type zeolite and a small amount of quartz. Using Jade 6.0 software and the peak fitting method, the content of the FAU type zeolite phase in the zeolite composite material is calculated to be approximately 22.99%, with a specific surface area of ​​112.34 m². 2 / g, the tetracycline hydrochloride removal performance test results showed that the material removed 96.83% of tetracycline hydrochloride from the aqueous solution.

[0055] Example 5

[0056] Al₂O₃ powder was added and mixed with iron tailings powder, adjusting the molar ratio of SiO₂ to Al₂O₃ to 4.7. Then, solid NaOH particles were added, adjusting the alkali-to-solid ratio to 1.0 before mixing. The mixture was then poured into a crucible and calcined in a muffle furnace at 5 ℃ / min to 550 ℃ for 3 h. After cooling, the alkali-activated raw material was obtained. The alkali-activated raw material was added to water at a liquid-to-solid ratio of 7:1 and stirred for 3 h to obtain a precursor suspension. This suspension was then poured into a polytetrafluoroethylene-lined reactor and hydrothermally crystallized at 100 ℃ for 14 h. The crystallized product was filtered, washed, and dried to obtain a porous zeolite composite material.

[0057] Through append Figure 1The XRD pattern shown indicates that the porous zeolite composite material prepared in this embodiment contains a large amount of amorphous phase, with a relatively low content of FAU-type zeolite phase and numerous impurity peaks. Using Jade 6.0 software and the peak fitting method, the content of FAU-type zeolite phase in the zeolite composite material is calculated to be approximately 30.14%, with a specific surface area of ​​130.40 m². 2 / g, the tetracycline hydrochloride removal performance test results showed that the material removed 97.34% of tetracycline hydrochloride from the aqueous solution.

[0058] Example 6

[0059] Al₂O₃ powder was added and mixed with iron tailings powder, adjusting the molar ratio of SiO₂ to Al₂O₃ to 3.7. Then, NaOH solid particles were added, and the alkali-to-solid ratio was adjusted to 1.2 before mixing. The mixture was then poured into a crucible and calcined in a muffle furnace at 5 ℃ / min to 550 ℃ for 3 h. After cooling, the alkali-activated raw material was obtained. The alkali-activated raw material was added to water at a liquid-to-solid ratio of 5:1 and stirred for 3 h to obtain a precursor suspension. This suspension was then poured into a polytetrafluoroethylene-lined reactor and hydrothermally crystallized at 100 ℃ for 14 h. The crystallized product was filtered, washed, and dried to obtain a porous zeolite composite material.

[0060] Appendix Figure 1 The XRD pattern of Example 6 shows that a single type of FAU-type zeolite phase was synthesized, with sharp peaks and no other impurity peaks. Using Jade 6.0 software, the FAU-type zeolite phase content was calculated to be 83.43% by peak fitting. (See attached...) Figure 2 The SEM images clearly show that spherical zeolite particles with a diameter of approximately 2 μm are uniformly distributed and well-grown, while the flocculent material on the grain surface is amorphous aluminosilicate particles. EDS spectroscopy indicates that O, Si, Al, and Fe elements are uniformly distributed, confirming the in-situ doping of Fe in the framework structure and the surface loading of the zeolite material. Figure 3 The N2 adsorption-desorption curves and pore size distribution diagrams show that the prepared porous zeolite material has abundant microporous structures and a small amount of mesoporous structures, with a specific surface area of ​​534.10 m². 2 / g, with an average pore size of 1.94 nm and a total pore volume of 0.259 cm³. 3 / g. (Attached) Figure 4 The XPS spectrum further confirmed the uniform distribution of iron in the material, and that it was mainly Fe. 3+ It exists in the form of tetracycline hydrochloride. Test results for tetracycline hydrochloride removal performance show that the material achieves a catalytic degradation rate of 97.51% for tetracycline hydrochloride in aqueous solution.

[0061] Example 7

[0062] Al₂O₃ powder was added and mixed with iron tailings powder, adjusting the molar ratio of SiO₂ to Al₂O₃ to 3.7. Then, NaOH solid particles were added, and the alkali-to-solid ratio was adjusted to 1.2 before mixing. The mixture was then poured into a crucible and calcined in a muffle furnace at 5 ℃ / min to 550 ℃ for 3 h. After cooling, the alkali-activated raw material was obtained. The alkali-activated raw material was added to water at a liquid-to-solid ratio of 9:1 and stirred for 3 h to obtain a precursor suspension. This suspension was then poured into a polytetrafluoroethylene-lined reactor and hydrothermally crystallized at 100 ℃ for 14 h. The crystallized product was filtered, washed, and dried to obtain a porous zeolite composite material.

[0063] Through append Figure 1 The XRD pattern shown indicates that the porous zeolite composite material prepared in this embodiment contains A-type zeolite, P-type zeolite, and FAU-type zeolite phases, but the FAU-type zeolite phase content is extremely low. In addition, quartz and a large amount of amorphous aluminosilicate are also present, resulting in complex peak shapes. Using Jade 6.0 software and the peak fitting method, the FAU-type zeolite phase content in the zeolite composite material is calculated to be approximately 14.37%, with a specific surface area of ​​73.08 m². 2 / g, the tetracycline hydrochloride removal performance test results showed that the material removed 97.34% of tetracycline hydrochloride from the aqueous solution.

[0064] Example 8

[0065] Al₂O₃ powder was added and mixed with iron tailings powder, adjusting the molar ratio of SiO₂ to Al₂O₃ to 3.7. Then, NaOH solid particles were added, and the alkali-to-solid ratio was adjusted to 0.8 before mixing. The mixture was then poured into a crucible and calcined in a muffle furnace at 5 ℃ / min to 550 ℃ for 3 h. After cooling, the alkali-activated raw material was obtained. The alkali-activated raw material was added to water at a liquid-to-solid ratio of 5:1 and stirred for 3 h to obtain a precursor suspension. This suspension was then poured into a polytetrafluoroethylene-lined reactor and hydrothermally crystallized at 100 ℃ for 14 h. The crystallized product was filtered, washed, and dried to obtain a porous zeolite composite material.

[0066] Through append Figure 1 The XRD pattern shown indicates that the porous zeolite composite material prepared in this embodiment is mainly composed of quartz, with a certain amount of FAU-type zeolite and sodalite. Using Jade 6.0 software and the peak fitting method, the content of the FAU-type zeolite phase in the zeolite composite material is calculated to be approximately 46.02%, with a specific surface area of ​​166.81 m². 2 / g, the tetracycline hydrochloride removal performance test results showed that the material removed 97.41% of tetracycline hydrochloride from aqueous solution.

[0067] Comparative Example 1

[0068] Al₂O₃ powder and SiO₂ powder were mixed, and the molar ratio of SiO₂ to Al₂O₃ was adjusted to 3.7. Then, NaOH solid particles were added, and the alkali-to-solid ratio was adjusted to 1.2 before mixing. The mixture was then poured into a crucible and calcined in a muffle furnace at 5 ℃ / min to 550 ℃ for 3 h. After cooling, the alkali-activated raw material was obtained. The alkali-activated raw material was added to water at a liquid-to-solid ratio of 5:1 and stirred for 3 h to obtain a precursor suspension. This suspension was then poured into a polytetrafluoroethylene-lined reactor and hydrothermally crystallized at 100 ℃ for 14 h. The crystallized product was filtered, washed, and dried to obtain a zeolite material synthesized from a pure silicon-aluminum source.

[0069] Appendix Figure 1 The XRD pattern of Comparative Example 1 shows that a single type of FAU-type zeolite phase was synthesized from a pure silicon-aluminum source, with clear and sharp peaks. Using Jade 6.0 software, the content of the FAU-type zeolite phase was calculated to be approximately 82.45% and the specific surface area was 492.70 m². 2 / g, the results of the tetracycline hydrochloride removal performance test showed that the material removed 9.01% of tetracycline hydrochloride from the aqueous solution.

[0070] Comparative Example 2

[0071] Natural clinoptilolite was ball-milled and then sieved to obtain natural clinoptilolite powder.

[0072] Appendix Figure 1 The XRD pattern of Comparative Example 2 shows that the natural clinoptilolite powder is mainly composed of clinoptilolite with a small amount of microcline. The tetracycline hydrochloride removal performance test results show that this natural clinoptilolite removed 18.29% of tetracycline hydrochloride from the aqueous solution.

[0073] Appendix Figure 5 The experiment was conducted under the condition of pollutant concentration of 50 mg / L. The results showed that the FAU-type zeolite prepared by Comparative Example 1 using pure silicon-aluminum source and the natural clinoptilolite material selected in Comparative Example 2 had a certain adsorption effect on tetracycline hydrochloride in aqueous solution. However, the narrow pore structure limited its removal efficiency of tetracycline hydrochloride pollutant, and it did not show catalytic oxidation activity for tetracycline hydrochloride in the Fenton-like system.

[0074] In summary, suitable hydrothermal temperatures promote the formation of FAU-type zeolites, while higher temperatures tend to cause them to transform into P-type zeolites. Low silica-to-alumina ratios readily form A-type zeolites, but the content of the FAU-type zeolite phase increases with increasing silica-to-alumina ratio. Furthermore, a higher liquid-to-solid ratio leads to a decrease in the system's basicity, which is detrimental to zeolite crystallization and thus increases the content of amorphous aluminosilicate phases; while a lower basicity-to-solid ratio makes it difficult to fully activate the inert mineral components in the raw materials, hindering their transformation into zeolite structures.

[0075] Appendix Figure 6 The degradation kinetics curves of the porous zeolite composite material prepared in Example 6 for tetracycline hydrochloride solutions of different initial concentrations are shown. At lower initial concentrations (10-200 mg / L), the final degradation rate of tetracycline hydrochloride by the porous zeolite composite material can reach over 95%. When the initial concentration is further increased to 400 mg / L, the degradation rate can still reach 88.19% after 3 hours. This indicates that the material has excellent catalytic oxidation effect on tetracycline hydrochloride pollutants in a Fenton-like system, and the degradation rate is relatively fast.

[0076] Any aspects not covered in this invention are applicable to existing technologies.

Claims

1. A method for preparing porous zeolite composite materials from iron tailings, characterized in that, Fine-grained iron tailings and Al2O3 powder are activated by alkali fusion to obtain alkali-activated raw materials; then, the alkali-activated raw materials are mixed with water at a liquid-solid ratio of 5:1-9:1 and subjected to hydrothermal crystallization reaction at 90-120 ℃ to obtain porous zeolite composite materials. The fine-grained iron tailings have a particle size of no more than 0.075 mm; the chemical composition of the iron tailings, by mass percentage, is: SiO2 72%, Al2O3 7.64%, Fe2O3 9.22%, CaO 3.36%, MgO 3.16%, Na2O 1.60%, K2O 1.54%, TiO2 0.25%; The molar ratio of SiO2 to Al2O3 was adjusted to 2.0-5.5 by adding Al2O3 powder; During alkali fusion activation, inorganic alkali powder is added. The inorganic alkali is at least one of NaOH, KOH, Na2CO3, and K2CO3, and the mass ratio of the inorganic alkali powder to the total of fine iron tailings and Al2O3 powder is 0.8-1.

2. The calcination temperature for alkali fusion activation is 550-850℃, and the calcination time is 2-4h; The porous zeolite composite material is composed of zeolite and amorphous material, with the FAU-type zeolite phase having a mass content of more than 10%.

2. The method according to claim 1, characterized in that, The molar ratio of SiO2 to Al2O3 was adjusted to 2.7-4.7 by adding Al2O3 powder.

3. The method according to claim 1, characterized in that, During the synthesis of the porous zeolite composite material, some Fe replaces Al in the zeolite and enters the framework structure, while some Fe dissolves in the amorphous aluminosilicate phase, giving it high reactivity and exhibiting excellent catalytic oxidation performance against antibiotic pollutants in a Fenton-like system.

4. The method according to claim 1, characterized in that, FAU-type porous zeolite composites consist of structurally complete and regularly morphologically regular FAU-type octahedral zeolite and surface-loaded amorphous aluminosilicates. They possess a composite pore structure rich in micropores and partially mesopores, with an average pore size of 1.94 nm and a total pore volume of 0.259 cm³. 3 / g, with a specific surface area of ​​534.06 m². 2 / g.

5. The application of the material prepared by the method according to any one of claims 1-4, characterized in that, The porous zeolite composite material is used for the catalytic degradation of organic pollutants in wastewater.

6. The application according to claim 5, characterized in that, The porous zeolite composite material is used for the degradation of tetracycline hydrochloride in wastewater. A tetracycline hydrochloride solution with an initial concentration of no more than 400 mg / L is prepared in an Erlenmeyer flask, and the initial pH of the solution is adjusted to 2-3. 0.2-1.0 g / L of the porous zeolite composite material is added to the tetracycline hydrochloride solution, followed by the addition of 10 mM H2O2 solution. The mixture is then placed in a shaking chamber for reaction, and a degradation rate of more than 90% is achieved within 20-120 min.

7. The application according to claim 6, characterized in that, The initial concentration of the tetracycline hydrochloride solution was 10-200 mg / L; the initial pH of the solution was adjusted to 2; and the amount of porous zeolite composite material added was 0.4 g / L.

Images