Spinel and aluminosilicate composite Fenton-like catalyst derived from iron tailings and preparation method and application of spinel and aluminosilicate composite Fenton-like catalyst

Abstract

The invention discloses a spinel and aluminosilicate composite Fenton-like catalyst derived from iron tailings as well as a preparation method and application of the spinel and aluminosilicate composite Fenton-like catalyst. Solid waste iron tailings are used as raw materials, a powdery spinel and aluminosilicate composite material is prepared through an improved sol-gel-calcination technology, then the powdery spinel and aluminosilicate composite material, biochar and water glass are mixed, molded and calcined, and the granular composite catalyst is prepared. The method is simple and convenient to operate and low in cost, and has industrial preparation feasibility. The prepared catalyst can efficiently activate oxidizing agents such as persulfate and hydrogen peroxide to generate active oxygen species, and organic pollutants in mineralized water can be rapidly degraded. The method is characterized in that the catalyst is prepared from iron tailings in a high-valued manner, the specific surface area of the material, the generation efficiency of active species and the cycling stability are remarkably improved through structure optimization, the problems that a traditional catalyst is high in cost, poor in industrial adaptability and the like are solved, and an economical and environment-friendly new thought is provided for large-scale treatment of organic pollution through an advanced oxidation technology; the method has double benefits of tailing recycling and environmental pollution treatment.

Description

Technical Field

[0001] The present invention relates to the technical field of preparation of environmentally friendly functional materials and catalytic materials, and in particular to a spinel@aluminosilicate composite Fenton catalyst derived from iron tailings, and a preparation method and application thereof. Background Art

[0002] With the accumulation of organic pollutants (such as antibiotics and dyes) in industrial wastewater, sulfate radical-based advanced oxidation processes (SR-AOPs) have become a research hotspot due to their efficient mineralization capabilities. SR-AOPs activate persulfate to produce highly oxidizing reactive oxygen species (such as sulfate radicals, hydroxyl radicals, superoxide anion radicals, singlet oxygen, etc.), which can non-selectively degrade pollutants. At the same time, hydrogen peroxide, as the most common oxidant, can also produce hydroxyl radicals through activation, just like persulfate, and has a good degradation effect on organic matter. Currently, the activation methods for persulfate and hydrogen peroxide mainly include transition metal oxides (such as Fe2O3, Co3O4), carbon materials, and energy field assistance (such as ultraviolet light and ultrasound). Among them, heterogeneous transition metal oxide catalysts are considered to have the greatest industrial potential due to their high recyclability and controllable cost.

[0003] However, existing transition metal oxide catalysts still face multiple challenges. For example, single metal oxides (Fe2O3, CuO, etc.) have a single active site and low redox cycle efficiency. Although bimetallic oxides (such as spinel AB2O4 and perovskite ABO3) improve performance through bimetallic synergy, their synthesis relies on pure reagents, and the synthesis processes are mainly sol-gel, hydrothermal, and solvothermal, which are complex and costly. In addition, current catalysts mostly exist in powder form, which is difficult to separate and recover from water bodies and cannot be used in fixed bed or fluidized bed reactors. During recycling, they are easily deactivated due to the loss of active components (such as ion leaching) or structural collapse. Therefore, they have poor industrial adaptability, which restricts their large-scale application.

[0004] Currently, the large-scale storage problem of beneficiation tailings is becoming increasingly serious. Many tailings are rich in transition metals such as Fe, Ti, and Mn, which have the potential to activate persulfate and hydrogen peroxide. However, the direct utilization efficiency of tailings is low due to the complexity of their composition. Active minerals (such as magnetite and ilmenite) are often wrapped by inert components such as quartz and feldspar, resulting in a low specific surface area (usually <5m 2 / g), the active sites are difficult to expose. At present, researchers have used nickel-cobalt tailings (CN117181252A) and copper tailings (DOI:10.1016 / j.jhazmat.2023.133198) as raw materials, removed some of the inert aluminosilicate components in the tailings by alkali leaching, and then achieved mineral phase transformation by calcination to increase the specific surface area and the number of active sites of the catalyst. This method does not require the addition of additional chemical reagents, the modification method is simple, and it has great cost-effectiveness. However, the inert aluminosilicate components in the tailings are poorly reactive and difficult to remove. It is still difficult to increase the specific surface area using the above-mentioned modification method, and a large number of active components are still encapsulated. The performance improvement of tailings-based advanced oxidation catalysts is small, which makes its application range narrow. Iron tailings, as an abundant industrial by-product, has potential resource advantages. Current research has used electrospinning technology to prepare iron tailings into iron tailings-based catalytic membranes (DOI: 10.1016 / j.jece.2023.110143), effectively activating PMS to produce reactive oxygen species and degrading organic pollutants. However, none of these methods address the problem of the active components of iron tailings being largely encapsulated by inert components, resulting in limited exposure of active components in the tailings. This results in low utilization of oxidants such as persulfate and hydrogen peroxide, making it difficult to effectively remove pollutants. Summary of the Invention

[0005] The present invention provides a spinel@aluminosilicate composite Fenton catalyst derived from iron tailings, a preparation method and an application thereof, the purpose of which is to solve the above-mentioned problems existing in the background technology.

[0006] In order to achieve the above-mentioned purpose, the embodiments of the present invention provide a spinel@aluminosilicate composite Fenton catalyst derived from iron tailings and its preparation method and application. The present invention proposes a "reverse leaching-support reconstruction" strategy, using iron tailings as raw materials, and realizes efficient catalytic activation of oxidants and industrial application adaptation through the following innovative designs. (1) Directed extraction of active components and support construction: Using citric acid as a leaching agent and complexing agent, active metals such as Fe in iron tailings are selectively leached, while simultaneously retaining the aluminosilicate skeleton as a support, breaking through the traditional process's dependence on the degree of mineral dissociation; (2) Transition metal doping and spinel phase regulation: Introducing transition metal elements such as Mn, Co, and Cu and loading active components through a sol-gel-calcination method to form an iron spinel@aluminosilicate composite Fenton catalyst, utilizing a bimetallic redox cycle to enhance electron transfer efficiency; (3) Granulation process development: The powder composite material is composited with biochar and water glass to form granular catalysts with high mechanical strength and good hydraulic stability after calcination, which are suitable for fixed bed or fluidized bed continuous processing systems. The present invention not only realizes the high-value utilization of tailings resources, but also significantly improves the specific surface area, active species generation efficiency, cycle stability and industrial applicability of tailings-based catalysts through structure-performance synergistic optimization, providing new ideas for the large-scale application of advanced oxidation technology.

[0007] An embodiment of the present invention provides a method for preparing a spinel@aluminosilicate composite Fenton catalyst derived from iron tailings, comprising the following steps:

[0008] S1. Crushing, grinding, screening, washing, and drying the iron tailings in sequence to obtain iron tailings powder; adding citric acid solution to the iron tailings powder, heating and stirring to fully dissolve the active components in the iron tailings to obtain a mixed system;

[0009] S2, adding a transition metal salt to the mixed system, continuing heating and stirring until the mixed system becomes a gel, and then drying it to obtain a xerogel;

[0010] S3. calcining the dry gel, taking it out after calcination and grinding it into powder, and then washing the powder with water to remove unstable components to obtain a powdery spinel@aluminum silicate composite material.

[0011] S4. The spinel@aluminosilicate composite material and biochar are mixed in a certain proportion, water glass is added thereto, and catalyst precursor particles are prepared by extrusion granulation. The catalyst precursor particles are calcined to obtain granular spinel@aluminosilicate composite Fenton catalyst.

[0012] Furthermore, in step S1, the iron and aluminum contents in the iron tailings are above 8%, and the silicon content is above 15%; and the particle size of the iron tailings powder after crushing and grinding is controlled to be 100-300 meshes.

[0013] Furthermore, in step S1, the concentration of the citric acid solution is 0.5-1.0 mol / L, the solid-liquid mass ratio of the iron tailings powder to the citric acid solution is 1:10-1:20; the heating and stirring temperature is 60-90° C., and the stirring time is 0.5-1.5 h.

[0014] Furthermore, in step S2, the transition metal salt is one or a combination of nitrates, sulfates or chlorides of cobalt, copper or manganese, and the molar ratio of the transition metal ions to the iron ions in the mixed system is controlled between 0.5:1 and 2.5:1; the heating and stirring temperature is 90 to 110°C, and the stirring time is 1 to 2 hours.

[0015] Furthermore, in step S3, the xerogel is calcined at a temperature of 400-700°C for 60-240 minutes. Preferably, the calcination temperature is 500-650°C. If the calcination temperature is too high (>700°C), the catalyst crystallinity will be too high, resulting in reduced catalytic activity.

[0016] Furthermore, in step S4, the ratio of the spinel@aluminosilicate composite material to the biochar is 1:0.4 to 1:1, and the liquid-solid mass ratio of the water glass to the solid mixed powder (a mixture of the spinel@aluminosilicate composite material and biochar) is 2:1 to 4:1.

[0017] Furthermore, the catalyst precursor particles are calcined at a temperature of 500 to 700° C. and for a time of 60 to 120 minutes.

[0018] Based on the same general concept of the invention, the present invention provides a spinel@aluminosilicate composite Fenton catalyst derived from iron tailings prepared by the above method.

[0019] The present invention also provides the use of the iron tailings-derived spinel@aluminosilicate composite Fenton catalyst prepared by the above method in the treatment of organic wastewater. The iron tailings-derived spinel@aluminosilicate composite Fenton catalyst degrades organic pollutants in wastewater based on a catalytically activated oxidant; wherein the oxidant includes at least one of persulfate and hydrogen peroxide.

[0020] Furthermore, the organic pollutants include any one of different types of organic pollutants such as sodium dodecylbenzenesulfonate, tetracycline hydrochloride, rhodamine B and other common surfactants in water bodies, antibiotics, dyes, etc.

[0021] The above solution of the present invention has the following beneficial effects:

[0022] (1) Excellent catalytic performance: The granular spinel@aluminosilicate composite Fenton-like catalyst derived from iron tailings of the present invention exhibits excellent catalytic performance in Fenton-like reactions. The present invention proposes a "reverse leaching-support reconstruction" strategy, using iron tailings as raw materials, citric acid as a leaching agent and chelating agent, selectively leaching the active components in the iron tailings, retaining inert components such as aluminosilicate as catalyst supports, and constructing a spinel@aluminosilicate composite Fenton-like catalyst through transition metal doping and an improved sol-gel-calcination process. The obtained catalyst active components have high dispersion, the active sites are fully exposed, and can efficiently activate the oxidant to produce highly oxidizing active oxygen species. These active oxygen species can quickly degrade various difficult-to-degrade organic pollutants in wastewater, such as surfactant molecules in washing wastewater, antibiotic molecules in aquaculture wastewater, dye molecules in printing and dyeing wastewater, etc. In addition, the catalyst ion leaching is extremely low and will not cause secondary pollution to the water body.

[0023] (2) Resource Utilization and Environmental Protection: This invention uses iron tailings as the primary raw material, selectively extracts active metals using citric acid, and retains aluminosilicate as a carrier, achieving high-value utilization of both inert and active components in the tailings. Compared to traditional catalyst synthesis processes, this significantly reduces raw material costs and solves the land occupation and environmental pollution issues associated with tailings accumulation, aligning with the green recycling concept of "waste treatment with waste."

[0024] (3) Strong industrial adaptability and wide application range: A catalyst granulation process has been developed. The mechanical strength is enhanced by the synergistic effect of biochar and water glass. The pores in the biochar give the catalyst a large specific surface area and abundant active sites. The prepared granular catalyst can be directly used in fixed-bed and fluidized-bed reactors, which is conducive to the realization of continuous and large-scale sewage treatment processes. After repeated use, the granular catalyst still has a relatively good degradation rate for organic pollutants, which reduces the frequency of catalyst replacement, reduces the cost of use, and improves the service life and economic efficiency of the catalyst.

[0025] In summary, the present invention uses natural iron tailings as the main raw material, and prepares iron tailings-derived spinel@aluminosilicate composite Fenton catalysts through the "reverse leaching-support reconstruction" strategy, which has significant economic, environmental and technical benefits. On the one hand, this method realizes the resource utilization of iron tailings, effectively solves the problems of land occupation and environmental pollution caused by tailings accumulation, and reduces the production cost of the catalyst; on the other hand, the prepared catalyst has excellent performance, good catalytic activity, stability and repeatability, and can efficiently activate oxidants to degrade different types of organic pollutants in sewage, such as sodium dodecylbenzenesulfonate, tetracycline hydrochloride, and rhodamine B. In addition, the granular catalyst is easy to use in fixed bed, fluidized bed reactors and other equipment, which provides convenience for continuous and large-scale sewage treatment and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0027] Figure 1 The process flow chart of the preparation method of the iron tailings-derived spinel@aluminosilicate composite Fenton catalyst of the present invention is shown.

[0028] Figure 2 These are scanning electron microscope images of the iron tailings particles of Comparative Example 1 of the present invention and the granular spinel@aluminosilicate composite Fenton catalyst of Example 1, wherein (a) is the iron tailings particles of Comparative Example 1, and (b) is the granular spinel@aluminosilicate composite Fenton catalyst of Example 1.

[0029] Figure 3 This is the X-ray diffraction pattern of the granular spinel@aluminosilicate composite Fenton catalyst of Example 1 of the present invention. DETAILED DESCRIPTION

[0030] In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.

[0031] Unless otherwise defined, all technical terms used hereinafter have the same meanings as those generally understood by those skilled in the art. The technical terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0032] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0033] The comparative examples and examples of the present invention use iron tailings from different regions of my country as raw materials, the compositions of which are shown in Table 1. The transition metal salts used in the examples are one or a combination of nitrates, sulfates or chlorides of cobalt, copper or manganese, and the citric acid and transition metal salts are all industrial grade.

[0034] Table 1 Main components of iron tailings from different sources

[0035]

[0036] The organic pollutant degradation experiments of the various embodiments and comparative examples of the present invention are all completed using a continuous catalytic degradation experimental device. The main body of the device is a cylindrical fixed bed, which is filled with quartz sand as an inert filler on the top and bottom, and a catalyst particle bed of a determined height in the middle; a constant flow peristaltic pump is used to transport organic polluted wastewater (containing oxidant) with a concentration of C0 to the fixed bed for catalytic degradation reaction, and the effluent after passing through the fixed bed reactor is collected to detect changes in pollutant concentration. The temperature of the fixed bed and the wastewater is controlled separately by a temperature control device to ensure the accuracy and stability of the experimental data. After the set experimental time, the concentration of organic pollutants in the effluent (C t The catalytic performance was evaluated by the degradation rate (Equation 1).

[0037] Degradation rate = (C0-C t ) / C0×100% Formula (1)

[0038] The following is a detailed description of the embodiments.

[0039] Example 1

[0040] The iron tailings used in this embodiment are produced in Shaanxi, and the Fe content in the tailings is 13.36%. The specific implementation process includes:

[0041] (1) The iron tailings are crushed, ground, sieved, washed, and dried in sequence to obtain iron tailings powder with a particle size of 200-300 mesh; a citric acid solution with a concentration of 1 mol / L is prepared; the iron tailings powder is added to the citric acid solution at a solid-liquid mass ratio of 1:10, and stirred at 80°C for 1 hour to form a mixed system.

[0042] (2) Add cobalt nitrate to the mixed system in the above step (1), with the molar ratio of cobalt ion to iron ion being 2:1, heat to 100° C. and stir for 1.5 h until the mixed system becomes a gel, and then dry it to obtain a xerogel.

[0043] (3) calcining the dry gel described in step (2) at a temperature of 600° C. for 120 min; after the calcination, grinding the product into powder, washing with water, and drying to obtain a powdered spinel@aluminum silicate composite material.

[0044] (4) The powdered composite material described in step (3) is mixed with biochar in a mass ratio of 1:0.4, and then water glass is added thereto, with the liquid-solid mass ratio of water glass to solid mixed powder being 2:1, and a granular precursor is prepared by extrusion granulation; the precursor is calcined at 500°C for 60 minutes to obtain a granular spinel@aluminosilicate composite Fenton catalyst.

[0045] Three equal amounts of granular spinel@aluminosilicate composite Fenton catalyst were taken and filled into three fixed beds. Tetracycline hydrochloride was used as the target pollutant (concentration was 30 mg / L), and peroxymonosulfate (PMS, 0.2 g / L), peroxydisulfate (PDS, 0.2 g / L) and hydrogen peroxide (H2O2, 2 mL / L) were added to the three tetracycline hydrochloride solutions respectively. M is defined as the ratio of the mass of the treated wastewater to the mass of the catalyst used. With PMS as the oxidant, when M is 100, the degradation rate of tetracycline hydrochloride is 94%, and when M is 2000, it still retains a degradation rate of 82%. With PDS as the oxidant, when M is 100, the degradation rate of tetracycline hydrochloride is 90%, and when M is 2000, it still retains a degradation rate of 78%. Using H₂O₂ as the oxidant, the degradation rate of tetracycline hydrochloride was 91% when M was 100, and remained at 76% when M was 2000. See Table 2 for details. The granular spinel@aluminosilicate composite Fenton-like catalyst effectively activated PMS, PDS, and H₂O₂, demonstrating high efficiency and long-term stability in the catalytic degradation of tetracycline hydrochloride.

[0046] Example 2

[0047] The iron tailings used in this embodiment are produced in Hebei Province, and the Fe content in the tailings is 15.90%. The specific implementation process includes:

[0048] (1) The iron tailings are crushed, ground, sieved, washed, and dried in sequence to obtain iron tailings powder with a particle size of 100 to 200 mesh; a citric acid solution with a concentration of 0.8 mol / L is prepared; the iron tailings powder is added to the citric acid solution at a solid-liquid mass ratio of 1:15, and stirred at 80°C for 0.5 h to form a mixed system.

[0049] (2) Add copper sulfate to the mixed system in the above step (1) with a molar ratio of copper ion to iron ion of 1.5:1, heat to 100°C and stir for 2 hours until the mixed system becomes a gel, and then dry it to obtain a xerogel.

[0050] (3) calcining the dry gel described in step (2) at a temperature of 650° C. for 150 min; after the calcination, grinding the product into powder, washing with water, and drying to obtain a powdered spinel@aluminum silicate composite material.

[0051] (4) The powdered composite material described in step (3) is mixed with biochar in a mass ratio of 1:0.6, and then water glass is added thereto, and the liquid-solid mass ratio of water glass to solid mixed powder is 3:1. A granular precursor is prepared by extrusion granulation; the precursor is calcined at 600°C for 90 minutes to obtain a granular spinel@aluminosilicate composite Fenton catalyst.

[0052] Three equal amounts of granular spinel@aluminosilicate composite Fenton catalyst were taken and filled into three fixed beds. Taking Rhodamine B as the target pollutant (concentration of 20 mg / L), peroxymonosulfate (PMS, 0.2 g / L), peroxydisulfate (PDS, 0.2 g / L) and hydrogen peroxide (H2O2, 2 mL / L) were added to the three Rhodamine B solutions respectively. M is defined as the ratio of the mass of treated wastewater to the mass of the catalyst used. Taking PMS as the oxidant, when M is 100, the degradation rate of Rhodamine B is 92%, and when M is 2000, it still retains a degradation rate of 80%. Taking PDS as the oxidant, when M is 100, the degradation rate of Rhodamine B is 88%, and when M is 2000, it still retains a degradation rate of 75%. Using H₂O₂ as the oxidant, the degradation rate of rhodamine B was 86% when M was 100, and remained at 77% when M was 2000. See Table 2 for details. The granular spinel@aluminosilicate composite Fenton-like catalyst effectively activated PMS, PDS, and H₂O₂, demonstrating high efficiency and long-term stability in the catalytic degradation of rhodamine B.

[0053] Example 3

[0054] The iron tailings used in this embodiment are produced in Shandong, and the Fe content in the tailings is 9.13%. The specific implementation process includes:

[0055] (1) The iron tailings are crushed, ground, sieved, washed, and dried in sequence to obtain iron tailings powder with a particle size of 200-300 mesh; a citric acid solution with a concentration of 0.6 mol / L is prepared; the iron tailings powder is added to the citric acid solution at a solid-liquid mass ratio of 1:20, and stirred at 80°C for 1.5 h to form a mixed system.

[0056] (2) Add manganese chloride to the mixed system in the above step (1) with a molar ratio of manganese ion to iron ion of 2.5:1, heat to 90°C and stir for 1 hour until the mixed system becomes a gel, and then dry it to obtain a xerogel.

[0057] (3) calcining the dry gel described in step (2) at a temperature of 550° C. for 90 min; after the calcination, grinding the product into powder, washing with water, and drying to obtain a powdered spinel@aluminum silicate composite material.

[0058] (4) The powdered composite material described in step (3) is mixed with biochar in a mass ratio of 1:1, and then water glass is added thereto, with the liquid-solid mass ratio of water glass to solid mixed powder being 4:1, and a granular precursor is prepared by extrusion granulation; the precursor is calcined at 700°C for 120 minutes to obtain a granular spinel@aluminosilicate composite Fenton catalyst.

[0059] Three equal amounts of granular spinel@aluminosilicate composite Fenton catalyst were taken and filled into three fixed beds. Taking sodium dodecylbenzene sulfonate as the target pollutant (concentration of 10 mg / L), peroxymonosulfate (PMS, 0.2 g / L), peroxydisulfate (PDS, 0.2 g / L) and hydrogen peroxide (H2O2, 2 mL / L) were added to the three sodium dodecylbenzene sulfonate solutions respectively. M is defined as the ratio of the mass of the treated wastewater to the mass of the catalyst used. Taking PMS as the oxidant, when M is 100, the degradation rate of sodium dodecylbenzene sulfonate is 91%, and when M is 2000, it still retains a degradation rate of 79%. Taking PDS as the oxidant, when M is 100, the degradation rate of sodium dodecylbenzene sulfonate is 89%, and when M is 2000, it still retains a degradation rate of 74%. Using H₂O₂ as the oxidant, the degradation rate of sodium dodecylbenzene sulfonate was 86% when M was 100, and remained at 75% when M was 2000. See Table 2 for details. The granular spinel@aluminosilicate composite Fenton catalyst effectively activates PMS, PDS, and H₂O₂, demonstrating high efficiency and long-term stability in the catalytic degradation of sodium dodecylbenzene sulfonate.

[0060] Comparative Example 1

[0061] The iron tailings used in this comparative example were produced in Shaanxi and had an Fe content of 13.36%. The difference between this comparative example and Example 1 is that the iron tailings were only crushed to obtain tailing particles with a particle size of 0.5 to 1 mm for use in the advanced oxidation catalyst.

[0062] Three equal amounts of iron tailings particles were taken and filled into three fixed beds. With tetracycline hydrochloride as the target pollutant (concentration of 30 mg / L), peroxymonosulfate (PMS, 0.2 g / L), peroxydisulfate (PDS, 0.2 g / L), and hydrogen peroxide (H2O2, 2 mL / L) were added to the three tetracycline hydrochloride solutions. M is defined as the ratio of the mass of the treated wastewater to the mass of the catalyst used. With PMS as the oxidant, when M is 100, the degradation rate of tetracycline hydrochloride is 21%, while when M is 2000, the degradation rate is only 11%. With PDS as the oxidant, when M is 100, the degradation rate of tetracycline hydrochloride is 26%, while when M is 2000, the degradation rate is only 5%. With H2O2 as the oxidant, when M is 100, the degradation rate of tetracycline hydrochloride is 18%, while when M is 2000, the degradation rate is still only 3%. See Table 2 for details.

[0063] Comparative Example 2

[0064] The iron tailings used in this comparative example were produced in Shaanxi Province, and the Fe content in the tailings was 13.36%. The difference between this comparative example and Example 1 is that no transition metal salt was added to regulate the active species. The specific implementation process includes:

[0065] (1) The iron tailings are crushed, ground, sieved, washed, and dried in sequence to obtain iron tailings powder with a particle size of 200-300 mesh; a citric acid solution with a concentration of 1 mol / L is prepared; the iron tailings powder is added to the citric acid solution at a solid-liquid mass ratio of 1:10, and stirred at 80°C for 1 hour to form a mixed system.

[0066] (2) Without adding transition metal salt, the temperature is continued to rise to 100°C and stirred for 1.5 hours until the mixed system becomes a gel, and then it is dried to obtain a xerogel.

[0067] (3) calcining the dry gel described in step (2) at a calcination temperature of 600° C. for 120 min; after the calcination, grinding the product into powder, washing with water, and drying to obtain a powdered iron oxide@aluminum silicate composite material.

[0068] (4) The powdered composite material described in step (3) is mixed with biochar in a mass ratio of 1:0.4, and then water glass is added thereto, with the liquid-solid mass ratio of water glass to solid mixed powder being 2:1, and a granular precursor is prepared by extrusion granulation; the precursor is calcined at 500°C for 60 minutes to obtain a granular iron oxide@aluminum silicate composite Fenton catalyst.

[0069] Three equal amounts of granular iron oxide @ aluminosilicate composite Fenton catalyst were taken and filled into three fixed beds. Tetracycline hydrochloride was used as the target pollutant (concentration was 30 mg / L), and peroxymonosulfate (PMS, 0.2 g / L), peroxydisulfate (PDS, 0.2 g / L) and hydrogen peroxide (H2O2, 2 mL / L) were added to the three tetracycline hydrochloride solutions respectively. M is defined as the ratio of the mass of the treated wastewater to the mass of the catalyst used. With PMS as the oxidant, when M is 100, the degradation rate of tetracycline hydrochloride is only 59%, and when M is 2000, the degradation rate drops to 15%. With PDS as the oxidant, when M is 100, the degradation rate of tetracycline hydrochloride is only 56%, and when M is 2000, the degradation rate drops to 12%. When H2O2 is used as the oxidant, the degradation rate of tetracycline hydrochloride is 55% when M is 100, and the degradation rate is only 7% when M is 2000. See Table 2 for details.

[0070] Table 2 Degradation effect of catalysts in Examples and Comparative Examples on organic matter

[0071]

[0072] Result analysis:

[0073] Table 2 above is a comparison of the performance of the Fenton-like catalysts in the comparative examples and examples in degrading organic matter.

[0074] Comparative Example 1 is a catalytic degradation experiment using only crushed iron tailings particles as PMS, PDS, and H2O2 catalysts, with tetracycline hydrochloride as the target pollutant, to evaluate its catalytic performance. It can be seen that the iron tailings particles can activate PMS, PDS, and H2O2, but their catalytic degradation performance and cyclic stability for pollutants are poor. The main reason is that the iron tailings are relatively dense, and there are inert minerals that encapsulate the active components, resulting in fewer active sites, a single active species, and poor catalytic performance. In Example 1, when the granular spinel@aluminosilicate composite Fenton catalysis is at M=100, with PMS, PDS, and H2O2 as oxidants, the degradation rates of tetracycline hydrochloride are 94%, 90%, and 91%, respectively. When M=2000, the degradation rates of tetracycline hydrochloride are 82%, 78%, and 76%, respectively, which are significantly higher than the effect of Comparative Example 1. The granular spinel@aluminosilicate composite Fenton catalytic active sites of Example 1 of the present application are fully exposed and rich in active species. Its utilization rate of PMS, PDS, and H2O2 is higher than that of Comparative Example 1, and its catalytic performance and cyclic stability are stronger.

[0075] Comparative Example 2 is a granular iron oxide @ aluminosilicate composite Fenton catalyst prepared without adding transition metal salts. Due to the high iron content in the iron tailings, the iron is attached to the surface of the inert carrier after being dissolved by citric acid. However, after calcination, the iron species mainly becomes Fe2O3, which has low catalytic activity and catalytic degradation performance is significantly worse than that of Example 1. Therefore, it is necessary to introduce other transition metal salts into the system so that the iron species is converted into a high catalytic activity iron-containing spinel phase during the calcination process to avoid the iron species from being converted into low-activity Fe2O3. Example 1 adds cobalt to the system to convert the catalytically active components into highly active species of CoFe2O4 and Co2FeO4 (if copper is added, the catalytically active components are converted into highly active species of CuFe2O4 and Cu2FeO4). The synergistic effect between the two metals accelerates the redox cycle of the transition metal and achieves efficient and rapid degradation of pollutants. However, the addition amount of transition metal salts should not be too much. Excessive addition will cause the supporting layer to be too dense, resulting in the inner layer active sites being covered, making it impossible to achieve a good catalytic effect and increasing the preparation cost of the catalyst.

[0076] Depend on Figure 2 (a) It can be seen that there are a large number of inert minerals in the iron tailings particles, which wrap the active components (Fe-containing minerals), and the tailings particles are relatively dense, so the active sites of the unmodified tailings particles are largely covered, resulting in low catalytic activity. The micromorphology and phase composition of the modified granular spinel@aluminosilicate composite Fenton catalyst of this application are as follows: Figure 2 (b) and Figure 3Its active components are mainly spinel phase, and these active components are evenly distributed on the inert carrier. A honeycomb structure appears on the catalyst surface, which increases the number of active sites and makes it easier for the oxidant to be adsorbed on the catalyst surface and further decomposed into a large number of free radicals, thereby achieving rapid degradation of pollutants.

[0077] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

[0078] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a spinel@aluminosilicate composite Fenton catalyst derived from iron tailings, characterized in that: The following steps are involved: S1. Crushing, grinding, screening, washing, and drying the iron tailings in sequence to obtain iron tailings powder; adding citric acid solution to the iron tailings powder, heating and stirring to fully dissolve the active components in the iron tailings to obtain a mixed system; S2, adding a transition metal salt to the mixed system, continuing heating and stirring until the mixed system becomes a gel, and then drying it to obtain a xerogel; S3, calcining the dry gel, taking it out after calcination and grinding it into powder, and then washing the powder with water to remove unstable components to obtain a powdery spinel@aluminum silicate composite material; S4. The spinel@aluminosilicate composite material and biochar are mixed in a certain proportion, water glass is added thereto, and catalyst precursor particles are prepared by extrusion granulation. The catalyst precursor particles are calcined to obtain granular spinel@aluminosilicate composite Fenton catalyst.

2. The method for preparing a spinel@aluminosilicate composite Fenton catalyst derived from iron tailings according to claim 1, wherein: In step S1, the iron and aluminum contents in the iron tailings are above 8%, and the silicon content is above 15%; and the particle size of the iron tailings powder is controlled to be between 100 and 300 meshes.

3. The method for preparing a spinel@aluminosilicate composite Fenton catalyst derived from iron tailings according to claim 1, wherein: In step S1, the concentration of the citric acid solution is 0.5-1.0 mol / L, and the solid-liquid mass ratio of the iron tailings powder to the citric acid solution is 1:10-1:20; the heating temperature is 60-90° C., and the stirring time is 0.5-1.5 h.

4. The method for preparing a spinel@aluminosilicate composite Fenton catalyst derived from iron tailings according to claim 1, wherein: In step S2, the transition metal salt is at least one of nitrate, sulfate or chloride of cobalt, copper or manganese, and the molar ratio of the transition metal ion to the iron ion in the mixed system is controlled to be 0.5:1 to 2.5:1; the heating temperature is 90 to 110°C, and the stirring time is 1 to 2 hours.

5. The method for preparing a spinel@aluminosilicate composite Fenton catalyst derived from iron tailings according to claim 1, wherein: In step S3, the calcination temperature is 400-700° C., and the calcination time is 60-240 min.

6. The method for preparing a spinel@aluminosilicate composite Fenton catalyst derived from iron tailings according to claim 1, characterized in that: In step S4, the mass ratio of the spinel@aluminosilicate composite material to the biochar is 1:0.4 to 1:1; and the liquid-to-solid mass ratio of the water glass to the solid mixed powder is 2:1 to 4:

1.

7. The method for preparing a spinel@aluminosilicate composite Fenton catalyst derived from iron tailings according to claim 1, characterized in that: In step S4, the precursor particles are calcined at a temperature of 500 to 700° C. for a time of 60 to 120 minutes.

8. A spinel@aluminosilicate composite Fenton catalyst derived from iron tailings prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the iron tailings-derived spinel@aluminosilicate composite Fenton catalyst prepared by the preparation method according to any one of claims 1 to 7 or the iron tailings-derived spinel@aluminosilicate composite Fenton catalyst according to claim 8 in sewage treatment, characterized in that: The iron tailings-derived spinel@aluminosilicate composite Fenton catalyst degrades organic pollutants in wastewater based on catalytic activation of an oxidant; wherein the oxidant includes at least one of persulfate and hydrogen peroxide.

10. The use according to claim 9, characterized in that The organic pollutants include any one of surfactants, antibiotics, and dyes.

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